Tool post grinder build Clough42 inspired

[PekkaNF]

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*

[PekkaNF]

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.

[PekkaNF]

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

[PekkaNF]

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.

[PekkaNF]

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.

[PekkaNF]

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

[PekkaNF]

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.

[RussellT]

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

[Sea.dog]

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.

[PekkaNF]

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.

[PekkaNF]

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

[Sea.dog]

Fine. I wasn't being picky, just wondering why, that's all. 

[PekkaNF]

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.

[PekkaNF]

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.

[PekkaNF]

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

[PekkaNF]

Looking good. And the hole is on the wrong side 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

[PekkaNF]

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.

[krv3000]

hi brill work

[PekkaNF]

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).

[PekkaNF]

Test assembly and power test went fine. Slight vibration at top rpm is belt is too loose.

[PekkaNF]

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