Author Topic: Tool post grinder build Clough42 inspired  (Read 16632 times)

Offline PekkaNF

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Tool post grinder build Clough42 inspired
« on: August 30, 2019, 01:00:01 PM »
There is excelent YouTube series: Making a Toolpost Grinder by Clough42

Playlist of the whole series.


Drawings etc.
http://clough42.com/2018/05/24/toolpost-grinder-part-24-first-test-grind/

First I have to complment him of showing his process. Very well represented and most ideas are clear and well put. One of best I have seen.

However, it would not be me, if I would't think that while it is very inspiring and well though, there are some features that i will take different approach.

I plan to use same over all design and most dimenssions as they are. This is no problem, because he basically worked with metric parts and dimenssions and when not, he showed the rationale.

I'll be most likely using 400W BLDC motor, that lost it's ER11 chuck on the other thread.
https://madmodder.net/index.php/topic,12957.0.html


I am torn between using a very good ER20 C20 extension or the one I don't have any use, but it is little minus tolerance on C20 shaft and 0,03 mm TIR on the ER-cone.

The part I am planning to deviate from original design is bearing arrangement and mounting.

While the original design relies threaded caps to fasten the bearings onto spindle body, I am thinking to mount them a little differently.

One clear departure is that I'm not using threaded caps, other how free brearing is mounted I will make two exra bosses to aid bearing removal, if it ever comes necessary. Front boss will have bit over 20 mm holes and will have light press fit into spindle housing. When front bearing is removed , 25 mm rod can be pressed inside of the spindle housing and this will meet the ID20 mm boss that will push the front bearing out at outer race (plan is to prevent brinneling through balls).

Front bearing will be fixed (as in the original design), however I'm planning to use light press fit and glue if necessary. Front bearing has a light press fit onto spindle (ER20 C20 extension), possibility to glue. There will be spacer/flinger on the spindle to locare the spindle onto front bearing inner race.

Rear bearing will have a sliding fit onto spindle body and it will be preloaded with a wave washer outwards. prper preload of this wave washer is when it is compressed to 1 mm wide space. There is a lgiht press fit boss, fairly similar than to eject the front bearing, but here it is to size a 1 mm space for the wave spring. I though that while the belt drive will most likely guarantee mininimum loading for the rear bearing to prevent balls from skidding and wearing out the bearing in no time, does not hurt to make it proper way. While lightly loaded bearing arrangement of this kind can work with a sliding fit between inner ring and shaft, it is not good habit when loading is higher, thus I'm considering gluing the rear bearing inner ring onto shaft, when it has proved to work and preload is established.

Some pictures of the progress this far.



Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #1 on: August 31, 2019, 04:04:14 PM »
There might be a small break on this one. I'm trying to work out half decent method to make a grooving tool for J-section polyvee belts. I know that 55 or 60 degree threading tools are used, but I am going to try to make tools close to 40 degrees. I am thinking of grinding HSS blank or 35 degree tungsten insert.

Offline djc

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Re: Tool post grinder build Clough42 inspired
« Reply #2 on: September 01, 2019, 05:49:47 AM »
There might be a small break on this one. I'm trying to work out half decent method to make a grooving tool for J-section polyvee belts.

Have you seen this thread https://madmodder.net/index.php?topic=8306.0 ? You are overthinking this. Use a standard 11tpi pipe chaser die (25mm or up European gas thread) and be done with it.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #3 on: September 02, 2019, 07:44:49 AM »
There might be a small break on this one. I'm trying to work out half decent method to make a grooving tool for J-section polyvee belts.

Have you seen this thread https://madmodder.net/index.php?topic=8306.0 ? You are overthinking this. Use a standard 11tpi pipe chaser die (25mm or up European gas thread) and be done with it.

Yes I have seen that. And NO, I am not overthinking this. YT build uses about 250W motor at 3400 rpm, two rib J-section belt. I'll be using 400W motor at 4000 rpm max and only slightly lower transmission ratio, around 1:1,7. Where do you get this "overthinking" part? The belt calculation programs I use indicate that it is bit marginal at 40N/rib belt tension with the length of the belt and sizes of the pulleys.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #4 on: September 03, 2019, 09:05:28 AM »
Went trough two different calculation program and few tables....it should be pretty standard, but belt is short and under 4 ribs is nonstandard. Calculations were made for Poly V-belt PJ 362 I.E. 140PJ and driver 57 mm dia, driven 34 mm dia.

More than few tables suggests that using this configuration and avoiding smallest pulleys PJ Poly-V can reliably transfer least 200w/rib at these rpms.

Talked to one design engineer at my work and he said that the calculation programs he uses allows easily over 200w/rib (four ribs) on the pulley sizes and spacing, without tensioning wheels, no problem there - in priciple. but it is not that clear cut.

But cutting down amount of ribs does not work linear because the there is less material to support the cords. Cord is spirally wound and when belts are cut from the sleeve the edge will have open cord end. Therefore going under four leads fast into compromise.

Another factor is that apparently this type of ribbed belt does not actually work like ordinary grouped V-belt. Apparently it can't really work with one rib only, needs two ribs least to stabilize and edge most ribs are not the most productive ones.

Therefore choices are:
1: 140PJ4, Standard belt, four ribs, only too wide and this will make set screw spacing somewhat difficult.
2: 140PJ3, Available, fits->this will be my choice.

Probably pure guess would have given close enough answer, but now I feel better :scratch:


Offline chipenter

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Re: Tool post grinder build Clough42 inspired
« Reply #5 on: September 03, 2019, 10:13:51 AM »
My tool post grinder has two ribs on a 1425 rpm motor geared up 4 to 1 with a 25mm diameter pully , and not had any problems using a 50mm grinding wheel .
Jeff

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #6 on: September 03, 2019, 01:08:58 PM »
My tool post grinder has two ribs on a 1425 rpm motor geared up 4 to 1 with a 25mm diameter pully , and not had any problems using a 50mm grinding wheel .

Thank you.

J-profile belt?

How big motor in wats?

Offline chipenter

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Re: Tool post grinder build Clough42 inspired
« Reply #7 on: September 03, 2019, 03:43:58 PM »
It's a small motor MadModder »
Gallery, Projects and General »
Project Logs »
Cheepo toolpost grinder and uses a ER16 collet chuck .
Jeff

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #8 on: September 04, 2019, 05:37:47 AM »
Hi Jeff, Found it:
https://madmodder.net/index.php/topic,10078.0.html

How does it works?

What is the story with the slits at the front of the bearing seat?


I like the grinding wheel guard.

Offline chipenter

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Re: Tool post grinder build Clough42 inspired
« Reply #9 on: September 04, 2019, 02:51:35 PM »
That's the piece that hold the bearing in parted off the cuts are on the outside to screw it in .
Jeff

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #10 on: September 11, 2019, 04:48:21 PM »
Didn't find ready 40 degree PJ-belt insert and since I don't have CNC I decided to modify 35 degree insert to 40 degree one.

Plan was to mill insert pocket into 20 mm rod.

When 20 mm rod is mounted into ER32 square block it can be easily indexed for 5 and 35 and 40 degree ngles needed to mill the insert pocket and modify the inser by grinding. Very standard machining not much to it. Just many steps and quite a few double test to make sure that didn't cut reverse direction to intent.

Originally I was thinking to use this rod to grind the insert only and keep it round, but the modified insert shorten significantly and I either had to modify good unused shank or modify this grinding fixture to be used in the tool holder too (that was my plan-B. Had to revert to plan-B.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #11 on: September 11, 2019, 04:58:10 PM »
The diamond wheel seem to produce fairly rough grinding. In the picture the grind appears even rougher than in reality. I honed the radius to cutting edge of the insert, milled flats to insert holder and made a test drive. Seems to work. Punge cut seemed to pruce easily proper profile. Full profile tool would be a whole more fun.

Now I only need 1,5 mm test pins or good wire to gauge correct depth of the belt grove when making the belt pulley.

I roughed one pulley and it's waiting chucked the gauge wire.

Maybe I need to mount one 12,5 mm travel dial gauge to give exact spacing and calculate table in advance.

Pekka

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #12 on: September 12, 2019, 08:12:08 AM »
Q: What would be correct grit to touch up carbide inserts? The standard wheel (around #100) seems to produce slightly too coarse grind. I haven't trued or dressed it yet.

I used vacuum/cyclone and filter. I was also wearing a respirator and didn't notice a thing. :lol:


Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #13 on: September 14, 2019, 06:58:10 AM »
Thinking of ordering 340 grit diamond to finish carbide smoother for aluminium.

Managed to make spindle pulley. It's still missing the two grub screws 90 degrees appart.

Ref:



Went pretty well, no hickups. First froove took some time to arrive to correct diameter. Rest were plunge cut to identical reading on the cross slide dial and just checked berore moving to next Z-position.
« Last Edit: September 14, 2019, 09:40:58 AM by PekkaNF »

Offline tom osselton

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Re: Tool post grinder build Clough42 inspired
« Reply #14 on: September 14, 2019, 07:29:55 PM »
A while back I went to get a motor for my Craftex mill and found out the spindles cost about $100.00 it is basically a rebrand of his mill in the videos.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #15 on: September 15, 2019, 03:13:29 PM »
A while back I went to get a motor for my Craftex mill and found out the spindles cost about $100.00 it is basically a rebrand of his mill in the videos.

??

Made a rookie mistake with the motor pulley. I got so distracted with the undersize 8 mm motor shaft dimession and decided to make it with a 8h7 reamer that seems to produce a little undersize hole. Well, pretty good size, but in a wrong place :doh: 0,04 mm of TIR.

6 mm boring bar just about fits into 8 mm hole, possible, but not ideal. But that is the way it has to be done.

I have three options, any other suggestions?

1: Use thin shim and bore the hole only 2xshim thickness bigger, Bit fiddly to fit.

2: Bore oversize hole into pulley, glue plug and bore correct diameter into that plug.

3: Make new pulley and not to cock it up this time.

Traditionally fixing a lemon takes only a little longer than to make it well.

Pekka


Offline chipenter

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Re: Tool post grinder build Clough42 inspired
« Reply #16 on: September 16, 2019, 02:32:56 AM »
You could also mount the pully on a arbour and turn the exterior concentric  .
Jeff

Offline philf

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Re: Tool post grinder build Clough42 inspired
« Reply #17 on: September 16, 2019, 02:52:43 AM »
Pekka,

There's another option.

Clean up the grooves concentric with the bore.

0.04 won't make that much difference to the ratio.

(Edit - have just seen that Chipenter has suggested the same fix.)

Phil.
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Location: Marple, Cheshire

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #18 on: September 16, 2019, 03:31:11 AM »
Thank you. Good suggestion! I'll try that first - 8 mm arbor with M8 thread should be pretty easy to turn....now what was the lead I did last screw cutting? 1 mm/r :lol:

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #19 on: September 17, 2019, 11:02:43 AM »
Busy day Yesterday, but managed to make a stub mandrell.

lathe change gears were at 1,0 mm lead and to avoid making a special nut I cut standard M6 thread. Hope that it still will pull the pulley tight enough to shave off a little from OD.

I used 55 degree insert for 6 mm spigot and thread and then cleaned upt the M6 thread with a standard die. Then I finished the mandrel diameter to pretty close 8,00 mm.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #20 on: September 17, 2019, 01:58:26 PM »
Thank you Jeff and Phil!

Turned it on the spigot and now it hardly shows any eccentrisity with 0,01 mm resolution DTI.

All went well, but made last grove 0,05 mm deeper -> had to revisit all of them to same depth. I tried to be smart and turned the exterior to theoretical diameter, when I checked with the pins it's a little "high" at 0,28 mm instead of 0,23 mm but doubt that I will see any problem with that.

https://youtu.be/fgyfZGYaaiY?list=PLDlWKv7KIIr-uFMjbe7AlsHswL6qihPPU&t=2640

Now back on track and they need grub screws.
https://youtu.be/fgyfZGYaaiY?list=PLDlWKv7KIIr-uFMjbe7AlsHswL6qihPPU&t=3503

Might even use this method, or I might use the spigot I made to fixt this screwup, mount motor pulley into square ER32 block and use it to index grub screws at 90 degrees to each others. Maybe.

* Removed YT links, for some reason shows wrong video at wring place...let's try hyperlink.
« Last Edit: September 18, 2019, 03:37:31 AM by PekkaNF »

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #21 on: October 01, 2019, 05:33:24 PM »
Few setback on materials, tools and flu. That shoud do it....a little delay.

My old relatively trusty russian vise needs a little TLC every now and then. All bolts repalced, but now it became glaringly clear that bottom need a regrind and that vise needs to be remounted in new location.

Therefore, deburring and measurement of flatness on granite surface plate, yesh, needs nearly 0,1 mm skim to get it nearly parallel. Trued the stone, used least four passes to get it relatively level, used tome time to deburr it and check with color that it is now reasonably straight and then back to surface plate to check that top and bottom surfaces are parallel.

Made new key to index it closer to T-groves, this time I was clever and made the key bit thinner than T-grove. Idea being that it still relatively easy to get close to few 1/100:s of mm just by pushing the key to abut on the grove and if it needs adjustment for any reason there is easy chance for it. Time will tell.

Rest is standard mounting and hardly needs comment.

Needed to move it about a little to find a spot on the table where it was fairly level to start with....could not find any burr or obvious bruise - mental note to check the table flatness one day with dye and DTI.

Pekka
« Last Edit: November 26, 2019, 05:41:59 AM by PekkaNF »

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #22 on: October 04, 2019, 02:30:47 PM »
Drilled and tapped holes for set screws.

Now I need to find proper soft pellets between set screw and motor shaft / spindle.

Ref. 58:30
https://youtu.be/fgyfZGYaaiY?list=PLDlWKv7KIIr-uFMjbe7AlsHswL6qihPPU&t=3513

Bit like that....forgot how he did...I have a little different equipment, did litte different, but pretty much same endgame.

Been planning belt tightener / motor clamp - this is quite different:

Motor is different and needs a flange mount, really can't mount it from circumfrence.
-> excentric tigntener would be awkward on motor side
-> excentric will be on spindle side

Don't have thick aluminium plate - I have steel 8x60 and such, but that is not big enough fot this constructio. I think I will fabricate it from plate and tube.


Pekka

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #23 on: October 05, 2019, 07:46:52 AM »
Time to assemble the spindle, since all parts are complete.

As mentioned before bearing arrangement is essentially similar, but construction is different: I don't use screw joint to retain the bearings - I am using press fit. Also free bearing has sliding fit on outer ring to spindle body, not between inner ring and shaft as in original design. Here these changes are more or less mater of taste. Maybe I am closer to text book example.

First I pressed the collar/dust cap on ER20 parallel shaft. Light press fit. It really didn't need any studlock.

Aluminium thingy is a press piece that will make sure that bearing is pushed on outer ring and goes straight - face and perimeter turned on same chucking.

Red tape indicates the fixed bearing side vs. free bearing side. All looks the same and dimenssions are the same. Excludung the bearing seat fix 0,02 mm different diameter is the difference between light pressfit and finger tight at 32 mm bearing size.

Then I pressed a bearing retraction flange into spindle body - light press fit too. This has nearly 21 mm hole in the middle - bearing and shaft is 20 mm and spindle body ID is bit ovet 25 mm. If the bearing has to be changed it's nice to knw that 25 mm drift will make fast job out of it. This flange has a little rim to meet bearing outer ring - just if I make a royal cock-up and need to modify this fresh from the start - can use old bearings.

Then I pressed in the fixed bearing - this bearing too is a light pres fit. Used aluminium bushing to make sure it does not brinnel and goes in straight.

I had an option of using glue to retain front bearing in the spindle body and shaft, but these fits feels perfect now.



Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #24 on: October 05, 2019, 07:57:04 AM »
This is another slight departure from the original. I use here one ring that abuts to wave washer, decided to make it fromseparate parts, because I could not decide how much to compress the wave spring and thickness of the push ring beween bearing and pulley.

Floaring end assembly starts by measuring the stack height of the parts and refer that to drawing/guestimate.

The wave spring retainer goes in innermost and it is light fit - I decided to use soft glue to retain it at proper place. I used aluminium plug mounted into grinding vice to set proper insertion depth (13,2 mm that is). Set it correct depth and let glue set one hour (time for groceries and recycle cardboard and other domestic recyclables).

« Last Edit: November 26, 2019, 05:43:24 AM by PekkaNF »

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #25 on: October 05, 2019, 08:12:36 AM »
And final assembly *of the spindle* was over in minutes.

Only one notable part was to preload the bearing by compressing the wave spring and the lock up the spindle pulley with set screws.

Spindle feels very good. I was expecting some float or springines in it, but it feels really smooth and proper.

Now I can take some measuremet and see how motor mount must locate in relation to spindle body to get pulleys in line.


20.10.2019 appended *of the spindle*
« Last Edit: October 20, 2019, 05:19:39 AM by PekkaNF »

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #26 on: October 07, 2019, 01:43:35 PM »
I think I figured what to make and in what order. Plan is to fabricate the the parts first, just cut and weld and in the end machine everything straight ans line...

The clamp has biggest weld and therefore most likely to warp structure. I'll weld it first and then make the slits and turn inner diameter straight again. When motor flange is welded into that it will not fit into lathe.

Game plan is to use short weld beads to attach the outrigger motor mount to keep distortion in bay.


Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #27 on: October 13, 2019, 04:57:07 AM »
That was welded up and it pulled 52 mm ID hole about 0,34 mm oval. Not too bad. Mounted it on lathe, bored the protruding part inside level, drilled taping hole and clearance hole, tapped and the used slitting saw to cut slits. It spring slightly and needed only very little truing in lathe to bring close to cylindrical bore.

Now the trouble is that I went too far ahead with aforementioned threading....I could have left untaped and done it last, but I was on automatic mode.....luckily there is plenty of material to go up from M5 to M6. Not elegant, but possibility.

I had hoped that when the outrigger mounting plate would have been welded it would be possible to turn on my friend's lathe. No such luck, it nearly does but not quite.

To make matters worse, I can't trust this on my boring head to do it in milling machine.

I have concidered somehow mounting it to lathe cross slide, but it has no T-slots or any other means of mounting piece there. It would need another project to build the boring bar and mount.

My easies option is not to distort it too much with weld.  :)

In past I have used gas torch to preheat the piece to whatever temperature felt right, but this is bit more sensitive. Don't want to get scale on the split clamp thread etc,

Q: How hot I should heat it? Just somewhere 300C, or even near dull red?

In the end I may need to buy boring head


Pekka

Therefore I need to try weld it with minimal distortion - maybe it

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #28 on: October 15, 2019, 04:41:58 PM »
Brother TIG-welded split clamp embro togeher.

Little tidying up and slitting to do. Made pretty conservative slit first, can open up them more later.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #29 on: October 15, 2019, 04:50:05 PM »
Funny how easy it is to cut with hole saw when there is place for swarf to drop. OD of the hole saw close to 60 mm and speed about 115 rpm. Bit of cutting oil and cut with one go.

Pickeled parts, jigged them together. Left about 1 mm clearance for weld joint.

Tack welded from the extreme ends and disassmbled the jig to check the straighness...needed just a touch and it seemed straignt enough.

A little preheat (maybe 200-300C) and welded 10-15 mm at a time, alternating sides and brushed the slag out. Few blemishes and craters, but this is not for gas tight joint - eye was to fiddle with it least amount possible.

In the end after grinding and pickele it was a around 0,17 mm exxcentric at 50 mm hole. Not too bad for this scale and purpose.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #30 on: October 15, 2019, 04:58:54 PM »
And funny how it is nearly impposile to punch ug out with hole saw when there are releve holes for swarf o disappear...I did not have rotabroach that big and deep, therefore joys of step drilling.

Bar stock is 60 mm OD mystery aluminium, bit gummy and not nest to cut. But I have one metre of of it.

So, I turned OD to fit to split clamp.

Then I set over one jaw of the three jaw chuck one tooth. Oldest trick in the world.

And proceed to stepdrill to 22 mm in three phases.

And then joys of enlarging the hole to near 38 mm with boring bar....carbide inser pruduced pretty rough bore, no matter what I did. I gave up and digged HSS insert and put grove to it. Still needed an cutting oil to produce good enough finnish. This material would be galling against similar AL like there is no tommor. Luckily I have steel on both sides.

Pekka

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #31 on: October 19, 2019, 06:10:49 AM »
Next challege was a motor plate:

1: I used belt calculator to see what is correct shaft distance and used it as mid point. Then a little experimentation that proved it righ. The big idea was use nominal shaft distance as a mid range - loosen to minimum and belt should come on and off. In the end reality seemed to confirm theorio exactly.

I draw features on the plate just to make sure I don't do something stubid and miss the target metric inch or something...

Tightened the mount plate on the milling vise over paralles, centered on spindle clamp and moved table calculated distance.

2: Motor mount using DRO PCD-function.

Motor mount has a flange OD near 25 mm OD and 38 mm PCD four M4 mount. First time ever I use DRO PCD function. needed a little study and two YT tutorials.

Second thing where to put the holes. Eccentric gives some latitude, but because it provides also belt tightening a little drawing etc, calculation, guestimation and stuck-and-see was order of the day.

M-Dro mill DRO worked exactly like the manual said. Some features were not very intuitive or logical....like "0" to CW PCD calculation or giving start and end angles for first and last hole, but thinkking it over carefully before making the holes worked fine.

Nice feature is that hole locations can be accessed multiple times with up/down arrows. I could check approximately I would be drilling on exact locations, could drill them 4,5 mm clearance holes (for M4 screws) and then use 8 mm slot drill to make pockets for bolt heads.

Then I mounted 25 mm rotabroach, moved back to zero point (centre of the PCD) and made last hole.

After deburring and wash was exiting moment to tryrif all mounts correctly. They did.

Next step is figure belt guard, grove to use hex keys for motor pulley set screws (a little tight fit between pulle and mount plate) and see in which direction to mount motor cable exit.

I haven't fiqured out exactl how to mount the grinder/drill. I was thinkking of using the same dove tail patern as QC-toolpost, but now I see trouble with that and probably will go for more traditional Dunmore post type......or something like that.

Offline RussellT

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Re: Tool post grinder build Clough42 inspired
« Reply #32 on: October 20, 2019, 03:58:59 AM »
That's looking good.  Does the clamp work OK for all positions of the eccentric?  I was wondering what happened if the slot on the eccentric was on the far side from the clamp slot.

Russell
Common sense is unfortunately not as common as its name suggests.

Offline Sea.dog

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Re: Tool post grinder build Clough42 inspired
« Reply #33 on: October 20, 2019, 04:58:41 AM »
Nice work, Pekka, but you seem to a problem with the PCD function. The rear two holes definitely look off centre from the scribed circle.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #34 on: October 20, 2019, 05:23:46 AM »
That's looking good.  Does the clamp work OK for all positions of the eccentric?  I was wondering what happened if the slot on the eccentric was on the far side from the clamp slot.

Russell

The eccentric is aluminium and the collar has some spring back. The M5 screw needs a fair nip but not near nominal torque to tighen all in a pacage. The clamp screw clearance hole needs a litte opening and closing slit as well. Weld pulled it a little out of round and when trued in lathe it needs a little more tightening than 0,9 mm slit allows.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #35 on: October 20, 2019, 05:38:03 AM »
Nice work, Pekka, but you seem to a problem with the PCD function. The rear two holes definitely look off centre from the scribed circle.

There were few contributing factors on this discrepancy:

1) Scribing and DRO were using a little offset zeros.....I realized that only when I was aligning it into milli vise.
* Scribing was centered on welded plate - that in turn was only eyeballed to slit collar assembly, hence a little uncertainty. I was concentrating only to get the plate face plane square to collar OD.
* DRO zero was centered to collar ID (normal centering in X/Y). and PCD had local (INC) zeroed to this computational centre - not into scribed centre. I felt I trusted more to math than my eyes.

2) Sloppy scribing.....using only ruler and while PCD scribe was fairly round 45 degree scribe lines did not come out exact (hot rolled edge, welds, not using surface plate, sines etc.)

3) Picture was taken in oblique angle, even holes don't look round but eye is master in seeing discrepancies. I am really sloppy with photocraphy and while I try to explain my logic (instead of very detailed punch by punch instructions) I often fail to verbalize my logic. I try to be more inspirational than instructional, because this has very little orginality and only few things are critical (like bearing aragenment and bearing fits).

I appreciate your comments. Thank you.
* Typos
« Last Edit: November 26, 2019, 05:29:34 AM by PekkaNF »

Offline Sea.dog

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Re: Tool post grinder build Clough42 inspired
« Reply #36 on: October 20, 2019, 06:26:00 AM »
Fine. I wasn't being picky, just wondering why, that's all.  :thumbup:

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #37 on: October 20, 2019, 09:59:15 AM »
No problem. Give a comment if you see something odd or going pear shape.

I started drawing the mount to lathe M16 tool post stud. Plenty of room there. I even found good chunks of mysterysteel. BUT problem is that I really don't have good way of making about 60 mm long 38 mm diameter hole.

Alternative method would be to make holes to two 12 mm thick hot rolled steel plate. This is bit easier in hole making, but to make them true and in one line after mounting would need another method. Also 12 mm thick plate does not leave huge amount of material for tighteneing apparatus.

I have 36 mm hole saw but that is pretty poor in long holes. Would need holes on circumference or slits, or something to let swarf to fall.

I have ordered boring head (old is pretty crappy) but it hasn't arrived yet.

Line booring in lathe would be completely unchared territory for me, but probably I need to go there.

Both methods are pretty labor intesive if I need to start from 25 mm hole.

Multiple choices, but none is obiviously superior.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #38 on: November 08, 2019, 02:22:17 PM »
Had a minor hickup. I had about 60x60 mm section of mystery steel. Cut cube out of it with band saw and it turned out to be very tough material. It was really hard to mill and I started thinkking that carving it o swiss chese might be hardder than necessary.

Then I found about 100 mm OD, lenght 75 mm offcut of spherical cast iron. Sawed it to bit over 50x60x70 mm block and started squaring it close to final dimenssions with the same milling cutter. Could get it close, but it refused to square up better than 0,1 mm and surface finish looked good, but was out of level. Even when spindle tram was checked straight and vise was square to 0,01 mm/100mm in both axis.

Put the block into TCG and immediatelly saw the problem. BAP face mill is way too brutal for this 300 kg mill-drill spindle.

Changed another face mill of 45 degree anfle and different insert and got closer with it. Then I choose two sides that were closest to straight line and chuck it back to bagnetic chuck and ground it parallel and clean. Way oversize but size is not issue, parallelism is and squares is high on list. urned out beter than 0,01 mm parallel (as grinding machine will do) but not quite perfectly square, mabe 0,03 mm / side. This level of paralleism and squares was not needed, but when I want to make my own tools it is nice to know that it can be done.

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #39 on: November 08, 2019, 02:43:23 PM »
That sorted out was time to make hole for the spindle. Plan was to reserve enough space in depth to allow 38 mm spindle and 16 mm toolpost screw to fit AND flexure to tighten whole thing up. Therefore attitide of the block is 50 mm height and 60 mm width (to drill/bore).

I didn't have a 38 mm rotabroach and the ones that allow 60 mm depth are not that cheap. I went huntig for core saws and afer testing three I concluded that nominally 37 mm hole saw would do the trick if used on both sides!

Centered the block with edge finder/DRO and checked that it looked ok.

Hole saws pretty much suck on deep cuts, made 10 mm groove to give some space for swarf to fall off.

Mounted the vise stop to allow making hole from the both ends. Double checked center position and sighted how it would fit. I was very concentrated to make the hole meet in the middle. everything had to be straight and repeatable.

Noticed that I used the last mm of depth capacity of the hole saw, that got me a little woried but the hole came out fine.

Pekka

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #40 on: November 08, 2019, 03:44:47 PM »
Looking good. And the hole is on the wrong side :doh: No wonder it was nearly too deep for the hole saw I checked. I was sooo concentrated squares and centering it that I made it to long side. That will complicate fitting and spindle clampping.  Decided to trundle on.

Boring it was simple, but I needed to chop one 12 mm boring bar for it.

Pekka

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #41 on: November 10, 2019, 04:49:47 PM »
Andrew paints few square meters on one go, I paint one small part...

Went pretty fast, because I had powder paint drying owen to chuck the part to dry.

I washed the part carefully, used hot air gun to blow it dry and then chucked it into owen at 100 degrees for half an hour.

Then two coats of filler (that works also as a base paint), light sanding after first coat (and light one after second coat, because I got few water droplets into paint - it was a heavy fog outside and I was painting it at garage doorway).

Then one thick fill of one part two componenet water carrier epoxy. Let's see how it works.

Offline krv3000

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Re: Tool post grinder build Clough42 inspired
« Reply #42 on: November 17, 2019, 07:11:15 PM »
hi brill work

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #43 on: November 19, 2019, 05:43:02 AM »
Thanks.

I did mention that I bored the hole on wrong side - that pretty much prevented me of using time honored split "casting" with screw clamping method.

Therefore I decided to put split cotters to use. Decided to drill and ream 12 mm holes symmetrically on both sides of M16 central stud hole and leave enough space to fit screws or other mounting hardware for OD grinding wheel guard.

The split cotters are made out of aluminium not to mar the spindle. I though of fancy circular cut like this:


This sorts of thing:
https://burdickjp.gitlab.io/2019/11/14/splitCollets01.html

But I find working with them fiddly if you need to remove the spindle - and on this design you may want to when swiching over radial/axial drilling/grinding on some ocasions. Therefore i first went on simple 45 degree bevel on both ends of the locking pins. Found out on first try that geometry is such that when tightened it will leave a small dent on this bevel. Not really a problem, but chucked the pins on lathe and turned the bevel to maybe 30 degree to give more contact area.

If bevel deformation ever comes a real problem I could make new pins put of harder Aluminium grade or use some sort of brass or bronce....

Next step is to make a spacer to adjust the grinding spindle axis to same level as lathe spindle axis. Originally I had a plan of making an adjustable pilar that would be coaxial to tool post mount screw, but boring this block on wrong intialy ate up all the space for this one too.....back to drawing board: Solid spacer "thick washer" it will be. I better measure it three times and cut only once.....

I could allready test drive it, but I don't want it to jump all over....(once happened to one servo motor - parameters were wrong and it was shaking violently - almost run off the table in split second).
« Last Edit: November 20, 2019, 03:47:35 AM by PekkaNF »

Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #44 on: November 25, 2019, 12:22:05 PM »
Test assembly and power test went fine. Slight vibration at top rpm is belt is too loose.


Offline PekkaNF

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Re: Tool post grinder build Clough42 inspired
« Reply #45 on: November 25, 2019, 03:44:41 PM »
Now TP grinder and QC toolpost are now compatible. Original top slide was a miserable piece of crap. Bought a little oversized QC TP kit, and extra toolpost for another lathe. Planning to adjust tool post gauge height that it could be used in both lathes.

For this smaller lathe the total inser height is 50,20 mm. Therefore TP grinder needs a spacer that has been ground to correct thikness.

Base plate has two different thread locations for toolpost: other to bring normal outside lathe tools to optimal location (over front dove tail bearing surface, the other location to maximum turning diameter, but tool tip will be in less optimal location.

Pekka