Author Topic: CNC Conversion lots of Questions! (Read 15096 times)

Garyrmck · « **on:** February 26, 2015, 05:07:33 PM »

Hello all,

this is my first post here so please be gentle !!

I am fairly new to metal work. In preparation for retirement in 2 years (or earlier if I'm lucky). I've been putting together a small workshop. All my life life I've worked with my head, but really wanted to work with my hands!!! So now I'm going to do it. At this point I have a SIEG SC4/510 HiTorque Lathe, a 6x4 Metal cutting bandsaw grinder, pedestal drill and lots of bits and pieces.

I would now like to buy a small milling machine. I am restricted in size by the space I have, and the ability to get the mill into place. The mill I am interested in is this one:

http://www.ausee.com.au/shop/category.aspx?catid=64

Now I know this is small, but most of the things I'm interested in are small - telescope parts (my hobby is astronomy and I have my own small observatory in the back yard). In the future I have dreams of building a live steam train when I've developed the skills necessary. The mill will be converted to CNC immediately (I work in computers).This mill has a higher speed than the SX2 here:

http://www.ausee.com.au/shop/category.aspx?catid=59

For small parts (that may have slots that are only 1-2mm wide), would the higher speed be a great advantage, or would I be better to get the larger mill?

The smaller mill has the advantage of full conversion plans being available here:

http://www.siegind.com/news_detail/newsId=33.html

It also has a fixed column and a larger table than the usual X1 mills.

Given my usage, would the smaller machine be OK? I figure if it is CNC, I can take shallow cuts without effort on my part. My ambition is to let it do the work, whilst I sit back with a scotch watching it........

Now would the following motor / driver kits be OK for either of these mills?

http://www.omc-stepperonline.com/3-axis-3nm425ozin-nema-23-stepper-motor-tb6600-driverr-kit-for-cnc-router-p-296.html

or this one - a bit less powerful in the motors
http://www.omc-stepperonline.com/3-axis-19nm270-ozin-nema-23-stepper-motor-tb6600-driverr-kit-for-cnc-router-p-171.html

Sorry for all the questions, but as I am on a budget I can't afford to make an expensive mistake.

TIA and
cheers
Gary in Australia

NeoTech · « **Reply #1 on:** February 26, 2015, 06:09:43 PM »

My tip is, can you afford it go with the bigger motors.. Holding power and torque is often a bigger issue in those mini mill conversions than speed.

I would say neither of those is a good conversion tho, but if space is a problem, and you are only gonna cut alloys - im guessing they work fine.. it will just take a buckload of time.

Before you choose controller, you need to decide on software. Are you gonna take the Mach3/4 route, Kflop route or are you going with LinuxCNC - TB6600 will work with either one.
But in the case of mach3 and Kflop you will prob. want a USB interface, because finding parallel EPP ported machines these days arent that easy. And if you are going linuxcnc, i would
suggest a cheap MESA card like the 7i90HD and a stepper driver.

I ended finished converted my BF20 mill, and found it lacking, it could do alloys but not touch steel. And that is a plenty bigger machines than those you are looking at.
So just never used it, it was faster hand cranking it on the Aciera machine ironicly.

So, what are you gonna make, is it only small telescope parts, are they all in alloys, do the require high precision, if so, precision needs ballscrews and they are not always that cheap. C7 graded ones is commonly used, but i choose to double up in those cases with an extra ball nut. And that adds cost.

I know this isnt an answer, its just more question to ponder about - before jumping into the pool. =)

John Stevenson · « **Reply #2 on:** February 26, 2015, 06:15:01 PM »

Go for the larger machine, OK it has a lower top speed but provided you only want to use small cutters you can increase the speed.
That kit you linked to is a joke. You will never be happy using the standard screws. Under CNC they really work especially doing circles and arcs, something it never does under manual moves and backlash will soon appear and it's then a uphill struggle for quality.

They also drive the Z axis from the back and the slides are on the front. What will happen is at each change in direction the head will tip before it changes direction.

Next thing keep well away from those all in one driver boards, for a start they are absolute $hit but if one driver goes and it's when not if the whole board is toast.

270 oz/in motors are more than enough for a machine this size, it's the driver that's rubbish. Also you need to drive the head via a 2:1 belt reduction and not bother with a gas strut.

Sorry if this sounds so negative but been there, done that, got the tee shirt and been sick all over it and I'd hate to see you start off on the wrong foot.

EDIT Just read NeoTech's post and not sure why he can't machine steel. We take the KX1, which is the same size as the second machine linked in the first post, to shows and machine steel and stainless with no problem. This is running Mach3 and no expensive Galil board which probably cost the same as the machine.

Brass_Machine · « **Reply #3 on:** February 26, 2015, 09:18:57 PM »

Go with a solid mount column X2. You will regret getting the X1. Go even bigger than the X2 if you can.

Plenty of info on converting the X2 out there. More perhaps than the X1.

Free X2 plans:

http://www.hossmachine.info/ - Ton of info

http://www.cnczone.com/forums/benchtop-machines/168634-cnc-12.html - nice conversion. Plans on this page but read the whole thing.

Eric

Brass_Machine · « **Reply #4 on:** February 26, 2015, 09:20:21 PM »

Not sure if you access to this model of X2, but I would buy this one if I was doing it again.

http://littlemachineshop.com/products/product_view.php?ProductID=3990&category=1387807683

Yes.. I own an X2

Garyrmck · « **Reply #5 on:** February 26, 2015, 09:45:52 PM »

Hi Guys,

I will go with the solid column x2 - this is the second model I linked in to in my first post - though from an Australian supplier. The plans I referred to will also fit the XY axis, as both machines share the same table.

cheers
Gary in Australia

Brass_Machine · « **Reply #6 on:** February 27, 2015, 12:10:56 AM »

Very good Gary!

I think you will be much happier. Check out the second link I posted for a neat plan for the Z axis. It is along the idea of what I plan to do mine. Mine is current converted to a 2 axis machine.

When you get a chance, please post up an introduction post.

Eric

NeoTech · « **Reply #7 on:** February 27, 2015, 04:55:33 AM »

Quote from: John Stevenson on February 26, 2015, 06:15:01 PM

Just read NeoTech's post and not sure why he can't machine steel. We take the KX1, which is the same size as the second machine linked in the first post, to shows and machine steel and stainless with no problem. This is running Mach3 and no expensive Galil board which probably cost the same as the machine.

Well im guessing he could, but it would prob. just be faster doing it manually with a file - part of running a cnc is to have faster turn around for many. Because most of us know that manual machining can take forever and be tedious as...#¤%# I find the Sieg machines lacking, both rigidity and spindle power. Same goes for the smaller Optimum machines and Grizzlys. - its why i went back to the Aciera instead of running the BF20 anyway.

This topic is kinda opinionated anyway. As that and you get 10 different answers based on each posters subjective experience. =)

hanermo · « **Reply #8 on:** February 27, 2015, 06:40:58 AM »

Agree, as usual, with John Stevenson.

Use belt drive 1:2 to 1:3.
Never use an integrated multi-axis drive.
Use HTD 5/15 mm belts (or GT or T5).

Cheap drives like the 2M542 series work very well, and can do above 100 kHz.
(To 4Nm, nema 23 to 48 V DC. Just what you need.)
These are the minimax solution, about 45€ each.

If you need better, you are much better going onto servos.
AC brushless servos are 150€ each, and 290 for a full kit with everything.

Brass_Machine · « **Reply #9 on:** February 27, 2015, 08:39:34 AM »

Quote from: NeoTech on February 27, 2015, 04:55:33 AM

...
This topic is kinda opinionated anyway. As that and you get 10 different answers based on each posters subjective experience. =)

That is for sure. It is like asking 10 people which car you should buy!

spuddevans · « **Reply #10 on:** February 27, 2015, 10:10:36 AM »

Hi Gary,

I did a conversion on a X2 a few years ago, build log is here http://madmodder.net/index.php/topic,3535.0.html

Tim

rythmnbls · « **Reply #11 on:** February 27, 2015, 04:29:34 PM »

Pics of my mad mod of an X2 can be seen here, It might give you some ideas

http://s87.photobucket.com/user/madluther/library/Mill

Regards.

Steve

Garyrmck · « **Reply #12 on:** February 27, 2015, 05:55:08 PM »

Thanks again for all the links - I have a lot of reading to do!!!

I'm interested in why some think that servos motors are better? In the astronomy world, which requires super accuracy in drives, I much prefer a stepper drive over servo's. For example I currently have a servo driven mount that is able to track with a worm gear accuracy of 6 arc seconds peak to peak (requiring super accurate worm gear manufacture), however the gear box required introduces lots of high frequency "noise", low in amplitude, but measurable nevertheless....My experience is a much smoother result from steppers...... Hence the query about servo motors.

cheers
Gary

John Stevenson · « **Reply #13 on:** February 27, 2015, 06:30:14 PM »

Servo's V steppers.

But after you have read this you will be no better off as there are many conflicting setups.

[1] Main difference between servo's and steppers is that servo's are equipped with an encoder so they know at any point where they are. [ more later ]
[2] Steppers are usually direct drive unless you need a reduction to get more power like on a Z axis as steppers have most power at low speed. Servo's OTOH need loads of reduction gearing as they run far faster which is where all their power is.

Main rule of thumb is steppers are OK on small machines, servo's are needed on large machines.

Now for the more later.

True industrial servo systems have the encoder feed back going to the controller so it knows where it is and if it isn't, can do something about it. Hobby servo's because they use controllers like Mach 3 that cannot take an encoder feed back into the controller rely on the feedback going into the driver.

Now the driver will do it's utmost to make it go where it's told but the controller is blind to this. The industrial setup is a true closed loop, the hobby setup is a quasi closed loop.

Now to throw even more into the pot you can now get three phase steppers with encoders, basically making then a servo system.

If you were confused to start with you will be more confused.

Long short on something like a SX2 or SX2P then stick to a well designed stepper system as it will do more than you and the machine are capable off. 3 axis servo's will probably cost, on their own twice what the machine costs and will not do anything any better given the donor machine.

Personally I'd go the ball screw route from the get go. You need one screw anyway because the Z is on a rack and pinion.

DO NOT ATTEMPT to motorise this, the errors are far to great and if you do I'll have you banned from this forum

You can get three ballscrews, with nuts from China for about £120 UKP don't know what that is in $OZ
3 steppers 270 to 350 oz/in
3 M542 drivers
Power supply rated at about 40v DC
Breakout board plenty of USB ones out there now from China so no worries about a computer. DO NOT USE A LAPTOP.
Hand full of shiny bits and you are done.

End of the day you will have a workable machine, not the best out there but also far from being the worst.

John Stevenson · « **Reply #14 on:** February 27, 2015, 06:35:47 PM »

One last thing.

Machine some decent stepper mounts up, plenty of designs out there. Do not use an open mount with 4 spacer tubes like you see all over the net.

It's a machine tool not a f#~'g grandfather clock.

Garyrmck · « **Reply #15 on:** February 27, 2015, 07:41:40 PM »

John,

how about this kit which includes the M542 Drivers?

http://www.omc-stepperonline.com/3-axis-3nm425ozin-nema-23-stepper-motor-m542t-driverr-kit-for-cnc-router-p-183.html

cheers
Gary

Garyrmck · « **Reply #16 on:** February 27, 2015, 07:46:16 PM »

Or this kit?

http://www.omc-stepperonline.com/nema-24-dual-shaft-cnc-stepper-motor-35a-31nm439-ozin-24hs343504d-p-384.html

cheers
Gary

John Stevenson · « **Reply #17 on:** February 27, 2015, 07:57:50 PM »

Quote from: Garyrmck on February 27, 2015, 07:41:40 PM

John,

how about this kit which includes the M542 Drivers?

http://www.omc-stepperonline.com/3-axis-3nm425ozin-nema-23-stepper-motor-m542t-driverr-kit-for-cnc-router-p-183.html

cheers
Gary

Good spec and kit for the price. No idea what you get hit for taxes US to OZ.
We get hit real bad here, that bad I no onger buy from the US, can't afford to, fact of life.

nickle · « **Reply #18 on:** February 28, 2015, 05:41:08 AM »

http://www.ebay.com.au/itm/AU-Free-Wantai-3Axis-Nema23-CNC-Kit-Single-Shaft-3A-270oz-4leads-Driver-4-2A-/221541450548?hash=item3394e64334

I got my steppers and drivers from Australian ebay. See the link above.. I have the electronics up and functioning with a minimum of

and the x axis on my x2 working on cnc at the moment ( its kind of like having a dro on one axis with a power feed) I am working on temporary arrangements for y and then I will have a shot at z.

x and y will be on standard screws for a while and I have the ball screw for the z. I'm not in a tearing hurry so it might take me a while to get through the rest of this job.

cheers,

Nick

Edited to update with correct link to the cnc kit I purchased.

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Author Topic: CNC Conversion lots of Questions! (Read 15096 times)