MadModder
Gallery, Projects and General => Project Logs => Topic started by: NeoTech on February 01, 2015, 05:49:54 AM
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So in casa NeoTech, the crazyness has stirred up under the winter and a new CNC machine build has been planned, parts begun to be sources.. So this is a bit of "so far i have."...
So basicly i started to read upon this polymerconcrete thingymajig. And its an awful interesting material. And an awful interesting theory of outcome and use.
But one thing.. even tho this material is a epoxy base concrete.. It still a concrete. Something most threads i have read seems to forget.
So my approach to this a bit different. Instead of casting in anchors i have decided to cast in a subframe as integral structure. And this is what i have come up with.
(http://www.roughedge.se/blogg/wp-content/uploads/2015/02/fPpuLwA-e1422833216615.png)
edit: changed out some of the internal frame after i reevaluated ridigity by reducing internals until it started to flex alot.
As seen a series of interconencting 2mm sheet parts are welded into the exposes metal parts that are meant for bolting stuff to. These in turn will be the reference points for the mold as well and later on ground parallell in place.
So this is basicly the project, and parts have begun to be sourced.
The list basicly looks like this atm.
-- Servodrivers: Granitedevices Argon - http://www.roughedge.se/blogg/wp-content/uploads/2015/01/IMG_0466-e1421069123861.jpg (http://www.roughedge.se/blogg/wp-content/uploads/2015/01/IMG_0466-e1421069123861.jpg)
-- Servomotors: 1.5kW 130mm framed Quadrature motors from MiGE (china) http://www.roughedge.se/blogg/wp-content/uploads/2015/01/2015-01-20.jpg (http://www.roughedge.se/blogg/wp-content/uploads/2015/01/2015-01-20.jpg) - Click this link for size reference, this is the motors intended for motion.
-- 32mm ballscrews with a 5mm pitch: ordered
-- 30mm linear guides from hiwin: ordered
-- Mesa 7i90HD + 7i48 Servo card: Ordered
-- Misc electronics parts: Orderered.
-- BT40 @ 8000rpm Spindle with ATC (chinese): Still haggling.
-- 7.5kW spindle servo motor from MiGE: Still haggling.
-- Lasercut metal parts for the frame: on hold until all cad is set in stone.
And yes yes, i know "buy an old machine and convert instead, bla bla".. not interested in that.
The whole project is, how would a polymerconcrete machine be able to behave - and what precision, speed and force would it be able to handle.
I plan to make the drawings, parts list and all that available on my website as an openhardware effort when i get that far.
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Neo, I'm eagerly awaiting to see this come to life, meantime just a couple of thoughts:
The Y rails don't seem to be exploiting the full width of the base - if they were further out (i.e. towards L / R sides of the base) then there might be less tendency for the saddle/table to droop when at min/max X travel - it looks like you could almost double the rail spacing within the same footprint.
The Y ballscrew looks to be quite a way below the saddle / rails - when its pulling or pushing, I suspect part of the force will be racking - trying to tilt / lift the front or back of the table - I'd be wondering about getting the ballnut as high as practical (like your X ballnut looks right beneath the table, in the same plane as the rails).
I'm not sure of the overall size of the machine; but the table looks a bit out of proportion to me. On my CNC mill, I tend to leave a vice mounted on the right of the table and use the left hand side for clamping-down, fixtures etc. Even if you're using a pallet-style or tooling plate to quick-mount your vice, there may be times when you need that length of table - e.g. using a fourth-axis and tailstock?
Dave
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Thanks, for constructive feedback. And you are right, there is alot of "height" for the Y axis down to the bottom screw, from the center of the ballscrew to the bottom side of the saddle its about 100mm. whichwill prob, create a problem. Each ballscrew will have double ballnuts, with the flange pointout outward in their respective travel.
The same problem actually exists under the pallet and behind the head.. And i havent figured something good here yet. The motor frames is 130mm and they require alot of free space to center well actually, more than one could imagine.
This is the main reason im not ordering the laser cut parts yet, i need to reiterade over this when i have the 32mm ballscrews and flange nut in my hand and know how they are in relation to the motors.
That palette is 400mm x 400 x 40mm mm palette. The idea of it is to have a quick lock system with 4-5 screwed inserts. (see attachments).
The overall travel of this machine would be in the range of half a cubic meter. - And the idea of a 4th and a 5th axis has occured to me, but atm im thinking of it as a module that can be lifted into the machine and locked into the pallette.
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cool project. 1.3kw would seen total overkill for this size machine. The epoxy grantir machines made by Nucky in the cncecke.de forum use 400-800W drives for roughly this size machine with very high performance.
What are you truing to acheive through the embedded sheet metal parts? You are still going to need to build forms for casting the epoxy granite.
Do you plan to source premixed aggregate, or mix your own. The difference in E modulus is suppossed to be about 2x between a home mix and a mix donebto the Fuller curve.
Have you designed in the way covers?
Mark
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You may want to consider a longer (wider) table, more like a Bridgeport-style mill. There are many setups where this length is an advantage.
If you swapped your table and the piece between that rides on the Y axis, it wouldn't be much different but it would give a lot more working area for larger parts and clamping support.
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If i can, i will try to source premixed aggregate - actually nothing that is sold in Sweden.. Dont know why. Something something, about enviroment something something.. :scratch:
You know those dilly wagger tree huggers, making it hard for people doing what they want.
If you have suggestion on a premix by name, i can see if i can source it from somewhere close, would be much appreciated.
The idea of the steel metal parts.. Well for one thing, what kills concrete in the end, vibrations that have broken it up and it wither and well breaks down.
And after looking at several of large machines built with this technique i notices they hade alot of sheet metal steel parts and fasteners within the casting.
But yes, i will still need to make forms/molds for casting this, its not a way to get around that problem. Im more thinking ridigity.
And when simulating this in solidworks, it reduces the elasticity of the casting by alot - so it seems to worke like rebar.. =)
About the 1.5kW motors. uhm well.. i talked to this chinese lady that really doesnt seem to speak english. And after alot of back and forth it ended up with "i take what the 99.8% of your other customers want in a 130mm frame".. and i got these.. they cost me like 600 usd, so not that expensive actually. =)
So if i wanna run a larger, longer table, that would mean i would make the saddle smaller. The big issue i see with that is that a smaller granite casting, even with reinforcment would be prone to breaking and flexing. And sure i could just make a larger table and space out the rollers, but that would limit travel instead. I need to ponder this tho, many people suggests the larger table, and just bolting down a wider palette ontop of that palette doesnt seem to be a good solution based on that. =)
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Well here is the build video that started me on this route anyway. =)
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That is an interesting video.
I will be watching this as much as I can. Have a huge interest in it. Spent most of a day a few years back reading the huge thread on CNC zone about this stuff. I have ideas to build on myself.
Eric
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To note from that video is that he uses a high performance fiber filled concrete for the base. And the polymerconctete is used for the saddle.
He does use some internal structures but most of it is just rebar bent and twisted and then welded to the anchoring points.
That will surely prevent ripout - but will it prevent fluid dynamics during resonance.?
The cnczone epoxy granite thread is mainly 600+ pages where the useful stuff is less than 20 pages. (i know i read em all, twice) ;D
There is actually several german and chezch builds with the material; polymerconcrete and high performance concretes.
And one thing that hits me after digging into this subject for the last 3-4 months - their machine bases is basicly completely dead in a resonance perspective.
Not even my half ton Aciera mill is that quiet many times when running a crab or a large endmill. =)
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I've come across this idea before in various threads but have yet to read exactly why you'd do this. I'm just looking for the the main talking points, not trying to start an argument or debate on the merits.
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Well why is a good question.
Mainly out of curiosity. And secondary because i exhausted ways of getting a 1-1.5t cnc machine into my shop by, just buying it.
I live in sweden, the country were logistics basicly stop at the border. I can find good deals in uk, holland and germany easily. And i can have them
shippe basicly to the border quite inexpensivly. (less than 2000 euro). But here we hit a snag. From the swedish border and home to me, its about
an 8 hour trip. For a like say a tormach with the more commong shipping companies that would run me an additional 4000-4500 euro.
And ontop of that they will want taxes for the import and such. A ok machine can be found for about 7500-10.000 euros no problem.
But when adding the shipping, im in a price range where buying a new one starts to be more affordable.
So i started researching alternative routes, and i knew i read the epoxy granite thread a while back, and i knew i have seen concrete machines in production
facilites i have visited before. So it seemed to be a valid route of doing things.
In the end i will have spent about 4500 euro on this, for that price i can even afford to make mistakes.
I have a small shop with a manual Aciera F3 and a small lathe, so i will be able to produce alot of the parts myself.
Only thing im a bit worried about is howto level everything properly.
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There is Silimix 282 from Euroquarz.de or Sikadur 43 from Sika. I contacted Euroquarz. The have no distribution network, but are happy to ship. Unfortunately shipping sand is very expensive.
Sikadur is sold as a system with the epoxy. It was used by Alpenheli.at for his gantry. He informed me it was about €7/kg back then when e made it.
I am still trying to source a fuller curve graded mix locally. Have you talked to local companies. The highest grades of concrete used in bridges (or at least in bridge repairs) also seem to use fuller curve graded aggregate.
I think the 2x theoretical improvement in rigidity gained by added all that steel would be much cheaper and more easily gained by simply increasing the profile depth of your E/G castings. One of the huge advantages of E/G is that it is a casting method which is not sensitive to changes in thickness or very thick sections (as cast iron is). Especially your base is not that thick relative to machine size. It would be very easy to add a few more cm in depth, maybe with some hotwire foam cut inserts to form ribs reducing the total E/G consumed, and thus acheive your stiffness goals. With the steel ribbed construction, you have to build the frame twice needing two very different methods to ensure alignment. Once in steel, then again the mould for the E/G. With some changes in profile depth you save a whole set of construction steps with no loss of performance.
The most active forum for practical E/G builders I found is CNCECKE.de (german language). Mineralguß is the german term for E/G. Nucky seems to have built the first one, and went on to make a business of E/G gantry mills. There are lots of other practicle examples of builds on there, including some which continued to post the performance of their machines in use.
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Thanks, will see if i can find a local dealer for those aggregates or if a car trip would be needed. ;D
I joined cncecke.de - but it does not work well through translate.google.com - and every other thread i clicked on didnt have any post the last 365 days.
so couldnt actually find the nucky thread. And overall it seems the germans have the upperhand on us in this subject. All the really working machines on the tube is from germany as well. =)
And ridigity, actually i agree with you - but... (there is a but).. Epoxy is like 30x more expensive than steel, i can have inexpensive 240mc steel cut from 2mm sheet, and welded onto bar stock with a jig alot cheaper than it would be adding more volume to the casting.
That said - a ribbed construction isnt something i had considered yet. And maybe i can reduce the amount of aggregate that way - because 7 euro kg, i need about 160 litres of the stuff as is ( no idea what one litre of E/G would weigh in at )
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Damn, i actually found Sika-43 in sweden.. *emailing companies* :clap:
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Epoxy is more expensive than steel is not a very good argument :)
Granite should be nearly free (obviously not if we have to have 25Kg bags of it shipped from Switzeland, but there must be some way of getting correctly graded aggregate locally, especially in Sweden and Austria. They countries are made of Granite aren't they?
You only need 8-9% epoxy. So it's maybe 16L for your current design, or say 20L of epoxy, if you bulk up your castings a bit. If you can get the aggregate cheaply locally, those extra four liters are not going to cost more than a fraction of what the steel, plus cutting, blus assembly, plus straightening that the steel will need.
Sikadur43 is 2.0 kg/l according to the datasheet. If you can still get it for €7 /kg you are looking at €2240 for the casting.
Euroquarz said that shipping 50kg of Silimix 282 to Vienna would be €170, and 20L of Expoy can be had over Ebay for under €300.
Mark
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Well, you could try to import Epoxy from ebay to sweden.. it would flagged in customs, confiscated and destroyed in those volumes.. (shitty country) something about enviroment rules and ****.. have tried it before - it was not a funny experience..
Granite is effin expensive here in aggregate form. Its common yes, and the companies crushing it knows its worth. Overall, you can take any price from europe or any other country and add a 0 on it, welcome to sweden.. =)
That "base" part is; 171500950.28 cubic milimeters.. i would get that to be around 171litres.. not 16-17 litres.. wrong?
Edited:
Pillar: 132656661.98 cubic milimeters (~132 litres)
Saddle: 26020000.00 cubic millimeters (~26 litres).
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Normally aggregate used in concrete is sold by the ton not the kg. You dont want crushed granite, you want the rounded stuff they dredge out of rivers. I am still assuming a local source can be found. 16L is the epoxy needed. I can get some graded 4-5mm pebbles, graded 0.8-1.2mm sand and a couple other grades at my local hardware store for about 4€ for 20kg. I am assuming if I drive the 40km to St Pölten when they produce the stuff and sell it in 1 ton bags to industry, I can get for next to nothing.
Why on earth would there be customs between Germany and Sweden? Haven't they heard that Sweden joined the EU a while back?
How do you plan to get the epoxy?
Mark
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well, customs.. epoxy falls under chemicals, Sweden has weird ass rules about chemicals. So they will try to make it as hard as possible for you to buy and handle.
Then you have this, and its a common thing here. Companies doing buisness in industrial materials - dont want private customers. Its to much hassle, they just dont want
to deal with end consumers. So its not that the materials is not available. They are not just available to me, as a private consumer. Because im mostly headache to them. =)
I was planning to use this epoxy; http://www.nilsmalmgren.se/Datablad/DB%20Gjutharts%20094.pdf
Its a casting resin where i can buy 53kgs of it for around 1500 euros.
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Sounds like you should take a ferry to germany, drive to Euroquarz dorsten and pick up Silimix, and then on the way home pick up 30L of Epoxy from some german vender like
Marlies Breddermann Kunstharze
Otto-Hahn-Str.22
48480 Schapen
Germany
, and save about €3000.
Mark
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I actually have to agree with you. A road trip would save me alot of cash.. Will just have to program a GPS and do a roundtrip bribing my other half with stops in some makeup store ;D
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"roundtrip bribing my other half with stops in some makeup store"
There goes the €3000 savings right there :)
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Your numbers add up to about a 650kg frame. What are you travels?
It sounds like your machine plan might be a little light. If it is about 180cm tall, it would be in a class where the industrial CNC machines are normally well over a ton. More like 2-5 tons if they designed for high dynamics (which your 1.5kW servos would imply).
Mark
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Ok, i got it to about 825kg actually. But yeah its a bit on the light side actually.
And that something that have been a concern of mine., its about 1500mm from top to bottom.
The travels is
z: 425mm
x: 450mm
y: 450mm
And the motors, and screws would put the machine somewhere in the 500ipm atm, thinking of gearing the axels with belts and push about 1100ipm - not entirely sure if thats possible tho.
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Well why is a good question.
Mainly out of curiosity. And secondary because i exhausted ways of getting a 1-1.5t cnc machine into my shop by, just buying it.
<snip>
Thanks, that clears up a lot.
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Hi Neotech,
I found my post in the Monster CNCzone E/G :
http://www.cnczone.com/forums/epoxy-granite/30155-epoxy-granite-machine-bases-polymer-concrete-frame-8.html#post245588
This summarises a book I got out of the library.
Mark
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This is actually great reading. damn i want that book and learn german..
Here is some design iterations...
Head is redesigned, the frame is bulked up, the hangout from Z is shortened, the table is made smaller for.. well reasons..
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Hi Neo ,
I can see this being a canny project to keep an eye on mate :thumbup: ,interesting design :med:
Rob
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So i thought i should dumpsom pictures.. of stuff sourced so far.
Start with an image of the last design iteration - can be useful i guess.
And after that first out, 16 pin connectors for encoders, aviation graded, 1.5kW servo motors for driving stuff around.
Granitedevices Argon Servo drivers, these i got for a hefty discount, thank you Tero over at granite.
And lastly a 6i25 + 7i77 + 7i84 MESA card setup, i first bought a parallell kit of this and couldnt find any good info - so thats a waste of money. But this should work.
Then cabinette., Hiwin 30mm rails with heavy load carriages and heavy preload, second 32mm ballscrews with double nuts and a 5mm pitch, and lastly claw connectors as im planning to directdrive this in the first iteration..
I need to get my hands on a 5.5kW Spindle servo motor that runs 3000rpm minimum - if anyone can scrounge up one for a good price point please gimme a shout.
And im still haggling over the BT40 spindle housing and pulleys with the chinese lady.. that drive a hard bargain.
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Who's been spending his hard earned cash then? :ddb:
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Hard earned is a stretch.. most of this is chinese actually.. not the cabinette - cuz that thing weighs a ton..
The most expensive is the Argon drivers. =)
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Can anyone gimme some input on this;
Roller plunger limit switch or rotary roller limit switch.?
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Magnetic proximity sensor - long term reliability - what virtually all recent professional machines use
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You have a link to what im looking for would be much appreciated. :)
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Hi Neotech,
After I received a copy of Thomas Zietz GradingCurve.XLS, I had a look at what my local hardware store had which would be useful aggregate. From the garden section I got 4x 25 Kg bags as follows:
5-8mm pebbles - http://www.quarzwerke.at/datenblaetter/Quarzkies_ME_5,0_-_8,0.pdf
2-4mm crushed rock - (No data sheet - this stuff is sharp edged crushed rock for spreading on the icy footpath)
0.5-2mm quarz sand for improving your grass - http://www.quarzwerke.at/datenblaetter/Quarzsand_ME_0,5_-_2,0.pdf
0.1-0.3mm quarz sand for grout - http://www.quarzwerke.at/datenblaetter/ME23-Beschichtung.pdf
Cool that the local quarry which supplies them publishes the datasheets with the screen sizes. Total cost of that 100kg was about €13.
I still have some very fine alumina from making a furnace, so that will be my finest filler. It cost €16,50 for 5kg from a pottery supplier.
So without even driving the 50km to the quarry, I could pick up a ton of aggreate for about €130 five minutes from home, although the alumina would get pricy for that amount.
Using the grading spreadsheet, it gives me the following recipe to make up a liter of Polymer concrete:
Grain 5 6,35 mm 100,00 26 % 259 ml 399 gr
Grain 4 3,00 mm 74,09 26 % 263 ml 403 gr
Grain 3 1,00 mm 47,74 20 % 203 ml 350 gr
Grain 2 0,25 mm 27,42 16 % 157 ml 243 gr
Grain 1 0,03 mm 11,74 12 % 117 ml 197 gr
100 %1000 ml 1592 gr
The two largest aggregates are wet, so I am drying some in the oven. I read that moisture has a very detrimental effect on E/G strength.
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:headbang: Very cool - i have found most of the grades as well but not the larger ones in a pebble state.. I can find coarse granite what is commonly used in concrete here in Sweden. Its not the rounded floodbed pebbles i had hoped for. I could find most of the aggregate i needed at a local flower and plants store in their outdoor section. When i said i needed about a ton in total of aggregate, they started to look funny at me. :lol:
You have my email in a message regarding the xls file. =)
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Recipe dont say how much epoxy. is it 10% on weight or 8% ??
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Because I am using super fine alumina, I'll do a test peice with 10% first.
By the way, nice motion hardware collection you have there.
Mark
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Thanks, need to start phase to, get steel parts, do casting experiments.. Get a spindle and spindle motor.. the last one is elusive. =)
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You have a link to what im looking for would be much appreciated. :)
This is the top(ish) end of the market:
http://www.sick.com/group/EN/home/products/product_portfolio/industrial_sensors/Pages/proximity_sensors.aspx
There are cheaper ones, ebay abounds
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Now all this talk about graded agregates sparked an unused neuron:
Concrete Springs:
Remember seeing a video that if tou mix GRADED glass spheres (i.e.Start with 2 mm dia spheres, the gap between them is Xmm so you add enough X dia. spheres. Now the gap is Y so you add Y dia spheres. Eventually you stop and add portland cement to lock it all together. Result is a Coil Spring.
Now back up to date:
Quick Google to check if my (only one) functioning neuron was Ok, I came up with thi spaper:
http://www.concrete.ie/downloads/ultra%20high%20strength%20concrete.pdf (http://www.concrete.ie/downloads/ultra%20high%20strength%20concrete.pdf)
NJoy! :smart:
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That was so weird reading. :thumbup:
I wonder how a polymerconcrete spring would act as a milling machine frame. :poke:
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I wonder how a polymerconcrete spring would act as a milling machine frame. :poke:
Well it would certainly put a spring in your cut :Doh:
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Will_D
That was a very good read. If they keep going they are going to figure out the right proportions to mix that dust to build what we now think is impossible. It is just about scary when you think about it. :lol: :lol:
Cheers :beer:
Don
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In engineering, everything is a spring! Nothing is absolutely rigid. You design for acceptable stiffness for your application.
Mark
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Just more design iterations..
Added anchors, changed the table, by adding 5mm to the platten of the saddle, fitted the ballnuts and figure out travels and such.
Will need to start making the way covers now to see how many i will need to make.. if they are gonna be thin and short there will be a shitload of them. *grmlbl*
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Your x bearing blocks look far too close together.
I just cast a polymer concrete test bar. Added 5g of carbon black from an old printer toner cartridge. Made 1.2kg of E/G nice and black. 10% epoxy was stiff but still sagged why a little vibration. I just tapped the mould on the floor for a few minutes. With a proper vibrator 8% epoxy should be fine.
I mixed in the aggregate from fine to coarse. The first and last were hardest to mix.
Mark
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Ah well, i cant fit them any other way, its wide heavy load bearing blocks. on a 30mm rail. So it starts to interferce with other stuff when moving around sadly. So its a bit of a compromise.
So the question comes to then i guess, can i conjour up a vibrator for a 300kg casting.. i have a 0.75kW electric motor that maybe could do the trick.. 1450rpm, a slightly offseted weight out of some aluminium roundstock maybe works?!
Got any picks of the brick? =)
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Your x bearing blocks look far too close together.
Mark
Neotech,
I noticed that too. When working at the ends of the table it's cantilevered. I think I would have the rails attached to the table and the blocks attached to the saddle. To do this you'd probably have to fix the screw to the table and the nut to the saddle. This way the spindle is always centred between the bearing blocks.
Just my 2p worth.
Cheers.
Phil.
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Have actually considered that approach.. should prob. take me the time to cad that out as well. Just redone the table like 10 times already so. =)
Would also allow for a smaller saddle with no overhang im guessing.
One of the issues i have is getting thick plate cut and drilled or even get hold of it. Its a bit why i approached the table like that. But i should reconsider that - and see what a slab of castiron cost actually.
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Normally, on the rigid industrial CNC's they put the blocks on the ends of the table and the rails on a fully supporting saddle. That gives the most rigid configuration. The way you have at now, you have the disadvantage of a full length saddle, with the low rigidity of bridgeport saddle.
Mark
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Yeah one of the designs i have looked at when doing this is this:
One of the problems with this machine is that it cant "touch off" on the table corners actually. It cant reach there with the mounted palette in the picture.
And the movent in X is really limited.. Its a chinese hurco clone.
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That is the trade off. What is more important to you - more travel, or more rigidity?
I posted a few pics of my E/G test piece here:
http://www.cnczone.com/forums/epoxy-granite/30155-epoxy-granite-machine-bases-polymer-concrete-frame-405.html#post1653506
Mark
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Nice, im guessing if you had gelcoated the inside and cast "wet on wet" into that you would have a somewhat smooth surface. =)
Atm im having issues with swedish vendors.. they will sell me 10kgs of resin, but not 100kgs. And on top of that i can find crushed aggregate but not smooth pebbles - apparently all pebbles and such is imported and are of danish or czech origin.
Need to find a different source for slow curing resin, apparently one without solvents so its not flagged as hazardous.
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The surfaces in contact with the tape are very smooth. I think a gelcoat is unnessary for what we are doing. The only defects in surface finish are just from lack of preparation whete I didnt bother getting the way smooth, or lack of vibration.
I also dont know why people plan to paint E/G. A little carbon in the mix and it looks great.
If you want to make a pebble path in your garden, the pebbles are imported from flat muddy Denmark into granite Sweden? Hope no Norwegians are ready this 😁
Mark
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Well they dont sell Smooth pebbles for path, i dont think ive actually ever seen it even.. you can get coarse pea pebbles in 2-5mm that will hurt your feet tho .=)
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Have you considered polishing the pebbles like they do with stones in jewelry. A machine like a concrete blender knocking the sharp edges of each other (don't remember the correct name of the machine now, Tumbler maybe)
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No not really, but now i do!. That would probably work - i need to get me a concrete blender im guessing, but a flat top blender would probably be what one would want.. need to take a dive into the adverts.
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There are a lot of videos on youtube about rock tumbling that might give you some ideas on how to do it, but it looks like that it takes some time and are a lot of noise from the process. I'm not to sure that a toploader is the answer because a sideloaded one shifts it more around at least in my mind.
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Yeah sideloaded "falling tumbler" throws it around more, and puts alot of more air into the mixture as well. and i imagine one would wanna keep as much air as possible out of this. =)
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If you look at the videos you will see that most of it are in closed containers filled with water and some grit I was just using concrete blender as an example.
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Another source of rounded pebbles could be the stones they use in bottom of fishtanks check the local zoo shop
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Don't you have any mountain streams?
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Nah i dont even have any mountains. =)
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I mean in the country! You must own a car..... and probably a shovel, yes?
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Ah well that i have, but still not really any mountain streams.. I live in the country of thousand lakes.
And most waters is protected, you cant just go dig anywhere you like. Ah well i could until i get caught but you know.. rules..
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..... - apparently all pebbles and such is imported and are of danish or czech origin.
Is this what we're talking about having no rounded stone in the entire nation? :scratch:
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Well i think you need to know a bit about our country before you getting into that.
We do have a lucrative market in crushing existing granite deposits into makadam, and we do have alot of sand and other earth materials for sale.
But what we are talking about here is pebbles, washed stones out of water areas, lakes, rivers and such. Almost all the water in sweden is protected from exploitation. Companies are literally not allowed to dig in them. And so arent we as citizens either. So making a product out of that resource is basicly illegal. And well the punishment doesnt really fit the crime. Even if you are a landowner arent you allowed to dig into or change these waters. Or actually really exploiting them. Because of one law.
That here is called "Allemansrätten", its kinda unique, but it make all of nature accssible to anyone, even other peoples owned land. But it also comes with the responsibility to not interfere with that nature for profit or exploitation.. This governs alot of our thinking regarding enviromental issues.
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Neo I wasn't thinking of removal from streams themselves, but streams move and leave deposits. This is what is normally used for stone. My state is highly environmentally conscious, and unless land is posted, like your laws, it also is available for recreation. Similarly it would be illegal to dredge rock from a stream here as well. But a landowner or gravel operation would be permitted to remove stone from areas where a stream no longer flowed.
The main reason I suspect you are having difficulty finding rounded stone is that crushed uniform stone is more valuable for concrete than round -- it isn't economically useful. Your particular purpose is flexible deadening of vibration, which is quite different to concrete purposes. But I bet if you tried you could find someone who has access to a legally available small quantity you need on his property. I mean the amount you want is tiny in commercial terms.
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Yeah you are prob. right. Just takes crapload of time to get hold of anyone.
And you are correct my volumes is way to small to be interesting for most commercial companies. They can and will sell me 20kg bags of the stuff for a crazy overprized sum of about 30 euros a bag.. And then i need about 45 bags of the stuff in assorted sizes and grades.
Just need to keep looking, or take a vacation to germany, the land of opportunity - and cheap industrial supplies it seems. =D
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Yeah you are prob. right. Just takes crapload of time to get hold of anyone.
And you are correct my volumes is way to small to be interesting for most commercial companies. They can and will sell me 20kg bags of the stuff for a crazy overprized sum of about 30 euros a bag.. And then i need about 45 bags of the stuff in assorted sizes and grades.
Just need to keep looking, or take a vacation to germany, the land of opportunity - and cheap industrial supplies it seems. =D
I may be misunderstanding something here, in which case i appologise, but smooth river rocks must be available?
Here's a page from Norway: http://www.maxbo.no/Produktkatalog/Uterommet-(Hage-og-fritid)/Heller-og-belegningsstein/Dekorstein-Arctic-Elvestein-25-40-20-kg/p/867546?gclid=CJXdsaGL-8MCFaLOcgodMm8A2g
20 kg. for ~10€. If you buy a lot a better price is a given. I also know this is a byproduct any place where they take out a lot of sand from old seabed and here at least you can go there with a trailer and fill it up for not much money?
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Henning, been looking all over this god forsaken country, most of the smooth decorative stone, is imported from either Denmark or Czech for some reason. And as you would know im guessing shipping anything in the nordic region tends to be quite expensive. So that same bag from Maxbo, we pay around 278 sek for that bagged in stores.
But as you are suggesting a round trip to norway would prob. not be out of the question. Anyway im considering to see if i can use concrete gravel seems like people on one of the swedish forums has actually have some success with that and pool sand.
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Here was us thinking that Sweden was the promished land of swedish chef and blonde swedish flight attendant with generous natures and questionable morals. Your are seriously damaging our illusions Neo.
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Well, let me know if you need any help! :beer:
I went to a local sand and gravel company some years back and filled a trailer with some larger stones which they find in the sand for 400 NOK. Probably close to a ton. They just had various heaps of different size stones which you helped yourself to and then paid on the way out.
I would never in this life expect to find anything cheaper here than in Sweden. I'm like this now: :jaw: :lol:
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Well, Henning, i have actually on more than one occasion went to Norway for buying boats.. They are cheaper there as well. =)
But you are right, almost everything are usually more expensive in your country.
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Boats too?
I'll be damned!
Not much else though. Certainly not good tools and machinery :(
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I need to pick your brains, and interest i guess.
So that 5.5kW motor on top of the head is weighing in at 45kg, the spindle is 35kg, the head is about 35kg, and the baseplate is around 20kg. So about 135kg.
The pitch on the lead screw is 5mm, its a 32mm screw and the head runs on 30mm heavy load linear bearings.. heres is the kicker..
The servo motor is a 1500W motor, that can hold 6Nm, and accelerate to about 18Nm, in my application the real acceleration is about 11Nm.
The question is.. would my servo motor be able to move that head without a counter weight. Or should i start thinking of redesigning the column in such a manner that counterweights could be added.
Im considering going with a 4kW motor instead and save 15kg, but - that would make me loose about 2Hp. I have decided i will go with a ABB motor tho - not just sure what size yet.
(http://i.imgur.com/WTCgg3x.png)
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So i had some issues with the idea of 130kg milling head. But i got this formula off of a friend.
6Nm / (0.005/2/pi) * 0.8 = 6032N
That basicly means that in the lowend of the servo motors i can accelerate 600kgs with somewhat ease. the motors is 2600rpm, but lets say you have friction some strain and other issues, so it drops to around 2400rpm. Means if i work within the 6Nm holding power range of the motor, that 600kgs would be able to accelerate with 12m/s in theory. My motors can accelerate 18Nm, but with Amperage being an issue there im prob. limited to about 11Nm.
Still i dont think 130kg of milling head will be an issue. Not even sure i would need a counterweight actually. But i should prob. gear it down with some form of beltdrive to 2:1 ratio so i can actually utilize the theoretical acceleration. *drawing new table mounts*
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You could always put in your design an easy way to add a counter weight if needed. Even if it is only to allow a spot of cables to connect and an easy way to mount the weight. Better to design for it now than have to hodge podge it later.
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I would design in gear or timing belt, least that gives you an option and there is always a possibilyt for a bigger servo.
But you definately need a brake that is spring operated and activates when power goes off. You might calculate how much the ball screw will hold when motor is off. My guess is that head weight would drive the motor and smash head down if fuse blows or something else would deactivate the servo motor.
If I understand it right couterweight is an option for slow machine. Counterweight adds mass, which you need to accelerate.
That might work out out, but if you need speed, you have a risk. If you have chains or cables AND you push the head down first (and shoot weight up) and then change direcion really fast you might hit it hard on rebound. Saw that happen once when masses were someting like 5t and and little smaller counterweight. Really big chains snapped and both parts crashed down.
Pekka
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Ah well i will prob. never go for a larger servo. The servos is 1.5kW in a 130mm frame. check my blog or earlier pictures i think i have them compared to a monster can of energy drink.
And im at the max for the servo drivers i bought.
But with that said, there is some deisng hinkys with putting a counter weight into this atm, for one i think i need to make the column wel mirrored, the outtake in the back atm, would be two outtakes on the sides instead and then i could prob. design some plate, gears, and chains.
The other way i think is to use wires and pulleys.. Where the weight hangs from a single pulley, and one end of that wire is stationary and the other end is connected to the faceplate for the head.
That could prob. be a hodge podge solution tho..
And as Pekka mentioned having 260kg accelerated will make for some funny behaviors when doing rapids. A friend of mine solve that by mounting the weight to a rail and using a brake on the slide, with no bearings, so when head is moving down it has some extra force needed for moving it down. guessing this could be achieved by making the weights between the head and counter different, but in reality you want to be able to move up faster than you wanna move down - at least in my head.
The third option i have been thinking of is some kind of "air spring" by utilizing like a fire extinguisher tank pressure lined and some form of piston, one could in theory create an airspring, but how practical is that that is the question i guess. =)
I need to take me a ponder... :doh:
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Holy crap 1,5kW servo. That is huge on on hobby size macine. It can some serious damage! Just gear it down, you will not need any couter weight. You need HW limit switched and one brake on lead screw to prevent the head from dropping when you power off.
Pekka
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Ah well its not a hobby sized machine it will be about 800 kg and half cubic meter of work area. And yes the driver takes hw limit switches and home switches Linux cnc take signal on the field bus as well so i will piggy back the hw signal to the field bus. :)
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So spent 3 days tinkering with the tramming possibility..
So basicly, 22mm holes, with a 16mm bolt, head is sitting on a 60mm dowel, and has a little "cam" that allows for tilting the head ever so slightly. That cam only has about 2.5mm radius, so it will not allow for alot of adjustment, but enough i think.
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So while waiting for the handymans to complete my new workshop floor, i continued making drawings..
Molds for base and pillar, so i know how much sheet will be used..
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Hi Neo
What do you reckon the column casting will weigh ?
Rob
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A rough guestimation puts it in the 350kg range, and the base at around 400kg, table in and around 75kg and the head casting around 90kg..
The idea with the molds is to brace them with 45x90 and load straps for cargo.
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So the BT40 spindle has arrived. It is suprisingly good quality. Wit a rod mounted in the spindle that sticks 150mm out from the spindle the throw is less than 1.5/1000mm
I spins smoothly with some "noise" im guessing it need lubricant. With it i got a 64 tooth pulley for the motor and 3 ER32 holders.
Final price with shipping for one of these is approx 1480usd - and thats with DHL Express shipping from china to Sweden (arrived within 5 days).
(http://www.roughedge.se/blogg/wp-content/uploads/2015/03/wpid-img_20150325_090731-e1427271325256.jpg)
(http://www.roughedge.se/blogg/wp-content/uploads/2015/03/wpid-img_20150325_090748-e1427271348352.jpg)
(http://www.roughedge.se/blogg/wp-content/uploads/2015/03/wpid-img_20150325_090739-e1427271339446.jpg)
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:drool: now that looks a real nice bit of kit :thumbup:
Were did you get the spindle from ?
Rob
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It's one of those Chinese manfactured OEM spindles you can find on alibabs.com . this one is a 130mm housing with 5 bearings. Which 4 them is angular contact bearings. Max rpm is 6000 and im guessing it needs some form of cooling. Need to ask the agent. :)
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Did you look at the tormach bt30 spindle?
http://www.tormach.com/store/index.php?app=ecom&ns=catshow&ref=BT_30_Spindle_Cartridge
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Ah well yes i did look at the Tormach Spindle at first, BT30 is nice size as well but a bit small for the rest of what im designing.
And even tho this BT40 spindle cost twice as much as the Tormach, the shipping was 1/3 of what Tormach wanted. I paid less than 300 usd for shipping, and Tormach wanted close to 700 for the BT30 spindle in shipping costs only.
And then im no fan or friend of Tormach actually. Find them to be a BS company, slapping their brand on chinese parts and bragging about how they did the RnD when its obvious OEM parts rebranded for the most of it. Take their "new" pathpilot for example - which is mesa cards (standards) with linuxcnc in the bottom. And the RnD was done by an external contractor. That type of marketing may work in the states, but doesn't work around here. And well are even illegal in my country. =)
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$700 shipping! :bugeye: :bugeye: :bugeye:
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Well im guessing its an effective way of not selling overseas. Shipping a PCNC1100 would run me about 6000usd.. I exhaused those things before i decided to try this build.
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$700 shipping! :bugeye: :bugeye: :bugeye:
Steve,
I don't know why the cost shipping stuff from the US is so high but it seems out of all proportion. It puts me off buying anything.
I've sold microscope objectives to the US and it's only cost me a few Pounds Sterling to send from the UK. Buying the same thing from the US might attract shipping of $50 or more ( and then when it arrives add import duty and VAT) - it's just not viable.
Phil
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Yeah i bought a tube bender :offtopic: it cost like 135 dollar - and the shipping was 48 dollar, and then came 13% customs on that and 25% VAT
In this case it even was a refurbished one, for bending stainless tubes..
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Yikes! For $6000 in shipping, one might as well have a vacation workshop abroad and ship there for $300. Land cost us $1200/acre, and there were trees to cut lumber to build. Of course I don't recommend the winters! :lol:
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Well im swedish.. winters doesnt really bother me, neither does cold or snow.. im used to it. =)
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It's the drive toward "premium" shipping that has created an insensitivity to shipping costs. There is often an inexpensive alternative, but manufacturers don't realize it (often not advertised well by the shiping companies) or are afraid of damage (not that there is actually any less liklihood with premium shipping).
This occurs domestically here as well. Now most Ebay sellers, for example send by a premium rated "Priority Mail" for small parts. This rate is often triple what "First Class" mail would cost for a small package under a pound in weight. The latter goes by airmail, and often arrives sooner than Priority Mail. Yet you are hard pressed to find First Class mail rates in signage at the post office, or online at the USPS website.
Try it on the USPS website - you'll see -- almost impossible to find first class mail for packages either domestic or overseas, yet it steers you into Priority Mail as quickly as possible. Check the difference in rates for sending something to Sweden, for instance between Priority Mail and First class.
Obviously you can't send a mill that way, but it's just an example of how many manufacturers don't actually get to see the difference in shipping rates available -- often it is office staff who unknowingly figure extreme shipping costs on an item, or even a web link to the shipping company's calculator application that does it.
For a high cost item, If you do your homework, find a good shipping company, and get a good rate, you can often contact a manufacturer by phone, and ask them if they will ship that way., and I bet 90% would agree to do that, if it's a no brainer for them.
Can't do anything about customs, or tariffs, but that's a local deal.
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So not been slacking off.. i needed some more space.. so well poured a concrete floor and made some walls..
(http://www.roughedge.se/blogg/wp-content/uploads/2015/04/wpid-img_20150414_123302-e1429008827472.jpg)
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:clap: :clap: :clap: I like the colour Neo :)
Rob
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Well gray is stylish.. will pour flooring epoxy at a later stage getting a 2-3mm thick protective surface. =)
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Nowt wrong with Grey , the floor dose look belting :thumbup: , how long before you can give it a coat of sealer and get things moved back in ?
Rob
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Guessing it will take a 4-6 weeks or so.. i can use the floor from a week from now, but not seal it until later.. humidity would make it crack if i did. =)
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So after several detours my shop is coming together, only some electrics and new doors left.
(http://www.roughedge.se/blogg/wp-content/uploads/2015/06/wpid-img_20150622_173508-e1434994273618.jpg)
My new compressor arrived a tad bit early, you can see it on the left there..
And this is from when i moved it in there.. by myself, by hand.. its effin 220kg..
(http://www.roughedge.se/blogg/wp-content/uploads/2015/06/wpid-wp-1434470376950-e1434470847229.jpeg)
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And it finally is time to move in..
Got lights up, gates inserted, electricity is drawn.. at last.. time to get back to the cnc part of this thread..
(http://www.roughedge.se/blogg/wp-content/uploads/2015/07/wpid-wp-1437078699869-e1437078788352.jpeg)