# Toolpost (or other) grinding in the lathe



## petertha (Oct 2, 2020)

I thought it might be beneficial to share information & experiences on this subject because it seems to come up often. The typical reason behind grinding in general is to achieve a high degree of accuracy as well as surface finish. Personally, I am interested in what you have achieved with classic 'lathe based' TPG (tool post grinders) like Dumore, Themac or maybe other brands out there. Specifically any example projects, metals, what kinds of abrasives, speeds, feeds, measurement controls.... Or maybe you built a custom accessory for grinding specialized work – bearing shafts, crankshaft journals, cylinder liners or other engine/tooling gadgets.

(I hope this link comes across) but this is one of my favorite posts of some of Jim Allen’s prior model engine work.
.90 cu in, 30,000 RPM, 7.2 HP custom built nitro engine

2 popular commercial TPGs
Themac Themac | Tool Post Grinders | Lathe Grinders
Dumore Tools - Dumore Corp

I’ll kick things off with my own (very limited) experience on the TPG front & some random pictures. Maybe like others I initially cobbled a Dremel type tool in a holder. If the parts were tiny, at best one could say they came out shiny as long as the magic smoke stayed in the motor. But dimensional accuracy was….hit & miss. What was I expecting with $10 bearings sitting in a plastic housing? Something approaching a die grinder was a bit better, but not really. Most suffered by lack of clamping rigidity IMO. I pondered some offshore integrated motor/spindles, some with handy ER collet shaft ends & variable speed typically used on homebrew cnc routers. But generally low-ish watts and/or rpm, seemed a bit more like a speculation buy & looking more & more like a 'real' grinder.

I hummed & hawed about building my own spindle. And soon recognized I knew little about specialized bearings, temperature compensation, specific spindle oils, motors or VFD’s, requisite lightweight belts to achieve low vibration shaft speeds between say 10-40K rpm, … Eventually I decided to get a Themac J35 when the $ opportunity presented. On the plus side it seems like high quality spindle, longstanding industry history, USA manufacture, variable spindle height positioning to suit different lathe swings, a range of OD & ID accessories, relatively easy mount to lathe compound with T-plate adapter.

On the negative side - cost! I suspect commensurate with what is involved to manufacture them. Although there are some used deals out there. The Themac also has kind of an oddball proprietary shank taper that inserts into the spindle cartridge & must be an accurate fit. Eventually I figured out dimensions & made a few arbors of my own. Grinding wheels of specific size & grit & abrasive are not exactly common either, at east in my part of the world.

The bigger rub with TPG’s in general (and maybe this is more my own naivety) is they don’t seem to play well with applications where work is supported by a tailstock (TS) center. The TPG spindle wants to be pretty much exactly where the TS is. And I would think TS support represents many if not the majority of typical precision grinding applications. One can extend the TS quill to full length which helps by presenting the smaller OD, but not really enough & also loss of support. Theoretically you could mount a large diameter wheel which would bring the spindle back out of the way of TS. But I run out of table extension if towards operator. One could mount the TPG at an angle & dress the wheel at an angle, but now you might be limited in terms of approaching a raised boss on the shaft & certainly couldn’t grind in between a small gap like crankshaft journals between neighboring counterweights. I had this idea to mount the TPG on my cross slide on the opposite slide to give more room & would also help stabilize the motor base. But most TPGs I’ve seen seem to be 3-4” max wheel dictated by fixed motor rpm + pulley arrangement.

So without this sounding too much like buyers remorse, just wondering if anyone else has some uplifting applications to share?


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## petertha (Oct 2, 2020)

First off - wheels. I found a few references to making your own. I was a little concerned about shooting my eye out, but my initial applications were ID grinding so maybe safer if it failed inside the part. So I bought a 1/4" wheel, came up with a drawing that swiss cheesed a bunch of profiles & had a water jet guy cut them. Quite accurate, about the same dressing effort. Offers a wide(er) range of grits & composition.

So far so good, no accidents. Now I find myself looking at my regular offshore Dremel stones with being held with a blob of epoxy on a piece of steel shaft, hmm.....


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## petertha (Oct 2, 2020)

Here are some of the Themac arbors & show the tapered section I was referring to. I'll post some custom arbors I made but reverse engineering the taper angle was kind of a pita. I don't have a taper attachment in my lathe which made matters worse. Eventually I got the taper recipie so it blued as good or better than the stock arbors. And heads up, the thread DP doesn't precisely match the typical class threads so the mantra is 'just replicate it'.


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## petertha (Oct 2, 2020)

Here is what I would call an example of a typical TPG mount up in the compound & successful grind - cylinder liner IDs. I've tweaked some improvements since these pics were taken, more to follow.


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## petertha (Oct 2, 2020)

I made this wheel dressing tool which clamps to the lathe bed. Goes without saying the ways are wiped of oil, covered, vacuum in position to immediately suck the abrasive dust.


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## petertha (Oct 2, 2020)

I found the biggest challenge was measurement of intended vs actual material removal. My DRO is 0.0005" resolution which is actually kind of coarse for most grinding applications. I was hoping to target say 0.0002" diameter resolution with some confidence & even that was leaving myself 1-2 thou final lapping allowance. The somewhat disturbing factor is once the TPG motor is on, it kind of makes micro vibrations accross the cross slide & the dials get 'lively'. My lathe lead screw / backlash / gib adjustment is in nice shape and I think the TPG motor assembly is well balanced. But it does impart a buzz to the machine.

When I lock the cross slide it stays put, but it became apparent early in the game I needed some better more absolute measurement. It took a couple iterations & everyone's machine is different but this what I came up with. A clamp that holds a 1.5" dial tenths reading indicator via T-slot mount. And a simple aluminum block with epoxied magnets to act as a plunger reference stop. I can reverse things around or screw in an extension rod to accommodate most setups. I got in the habit of stopping the TPG motor, make the DOC adjustment when everything was quiet, then take another pass. Reversing power feeding out of an ID bore was generally not a good thing. probably a function of my '98 vintage Taiwan lathe.

In reality grinding to a target is kind of a juggling act. The wheel might be wearing, it may require several spring passes to spark out. It has to stay cool or at least same temperature. I didn't mess around with coolant or air too much but I also wasn't removing much material thus far.


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## petertha (Oct 2, 2020)

Here is my recent idea of mounting TPG to the opposite of the spindle more or less directly on the cross slide. To my mind it eliminates a few extra sliding sources involved with the compound mount, kind of the wedding cake stack-up syndrome. Shows the normal mounting plate with hold-down nut. I would just bolt the motor to a new larger solid plate with c/s flathead bolts & then secure the plate via T-nuts. That part is straightforward, makes a nice line to the lathe spindle center. 

Mostly I was hoping for some tailstock clearance solutions to arise if I used a larger wheel, but it seems to be a dead end in that regard. I'll try to take a better pic of the tailstock conflict but hopefully you get the idea.


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## petertha (Oct 2, 2020)

And here is my sketch representation of the TPG spindle vs tail stock real estate conflict.


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## goldstar31 (Oct 2, 2020)

It's most interesting but it has been covered here and elsewhere - literally Donkkey's Years ago.

Nevertheless, it certainly has  has a place.

Somewhere else here there is a mention of several workers and Ian Bradley who also write as Duplex with Norman Hallows published a design in his book "the Grinding Machine'. Again, the excellent and quite revolutionary New Zealander -- Jack Radford also published a design in his book. Mention regularly appears here of the Quorn tool and cutter grinder and the 'cartridge' can be removed and used in the lathe.  So, in similar vein are the ones in the Stent and Kennet tool and cutter grinders.
More modestly,  years ago, I bought a wood router from Robert Bosch of Switzerland and found that it actually came from a tool and cutter grinder with a 1/4" /6mm collets.  So with a standard 43mm collar,  I made up a holder to put it on my - now gone Myford Super7B.
I still have it and a new-er Myford Super7B with power cross feed.

So I look forward  to further articles

Thanks

Norman


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## Lofty76 (Oct 2, 2020)

Heres one I knocked up using an unwanted (at the time) cheap 6" bench grinder, shown here finishing the main bearings of an R&B gas engine, Please note, this was a first try and the grinder does have a guard fitted now.


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## joneb (Oct 2, 2020)

I know this is a bit crude but it did the job but the method could be used for occasional grinding.


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## Lofty76 (Oct 2, 2020)

joneb said:


> I know this is a bit crude but it did the job but the method could be used for occasional grinding.



This is why true engineers will always survive armageddon - the ability to improvise. Well done


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## ajoeiam (Oct 2, 2020)

Maybe some kind of shielding for the lathe ways was added after the pics presented. 
If not - - - - would suggest doing so any time any kind of grinding is done on a lathe. 
The spent grit is still a grit and it truly plays hob with lathe ways. Its also a real pita to clean off of and out of all the nooks and crannies! 
As I was told of surface grinders - - - - they grind themselves to death.


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## Lofty76 (Oct 2, 2020)

ajoeiam said:


> Maybe some kind of shielding for the lathe ways was added after the pics presented.
> If not - - - - would suggest doing so any time any kind of grinding is done on a lathe.
> The spent grit is still a grit and it truly plays hob with lathe ways. Its also a real pita to clean off of and out of all the nooks and crannies!
> As I was told of surface grinders - - - - they grind themselves to death.


Totally agree, Just out of shot in my picture is a whopping great Magnetron magnet directly under the cut and in the coolant flow. It sticks nicely to the bedway and collects pretty much all of the grinding dust.


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## Larry G. (Oct 2, 2020)

petertha said:


> Here is my recent idea of mounting TPG to the opposite of the spindle more or less directly on the cross slide...



Thank you for your detailed description and photos of the project. THEMAC was located in my hometown until the last acquisition, still in the same area.  Goldstar appropriately notes that there is hardly anything new, except rediscovery of old solutions.


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## petertha (Oct 2, 2020)

Lofty76, that is a nice solution. Just to confirm, are you able to traverse the entire length of stock & the motor clears the tailstock in that setup shown? Is the grinding wheel itself 6" diameter or you just mean nominal grinder size? Do you recall offhand what the motor diameter is? Did you do any upgrades to the bearngs or used as-is? I have a 1/3hp slim motor light duty bench grinder but guessing its still 5" diameter. 

The nice part about spindles is they are slim by comparison & motor can be displaced out of the way via a belt. The Themac spindle is ~ 1.5-2" diameter. But the downside is making an appropriate arbor for a big wheel & probably too high of rpm using kit pulleys. Sourcing an appropriate motor may be the easier problem to solve as long as the rpm matches or could otherwise be controlled.


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## John Antliff (Oct 2, 2020)

Just to add my experience - 



This was my first time of using my Quorn spindle on the lathe and it went well although I somewhat resented all the time it took both to do the grinding and the very long clean up time required to remove all the damaging dust.  If I was charging my time then buying new rotors would have been preferential but as a hobbyist we don't mind substituting time for money!  It took me 3 years to build the Quorn and all the fitments required to sharpen difficult tools but I have never regretted the investment.


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## petertha (Oct 3, 2020)

Found this video by Don Bailey (of Suburban Tool fame) showing an OD grinder in action. Now that looks like the weapon of choice! Now that I see (large) wheel / motor / tail stock layout of the 'real' machine it rather confirms something more like what Lofty76 has accomplished. The ODG is a pretty robust piece of kit as one would expect. The entire bed/table pivots too, which explains how tapers are are ground & replicated consistently.


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## petertha (Oct 3, 2020)

Specifically dedicated to model engine cam shafts using what look like harvested Sherline components. But kind of similar layout recipe - a bigger diameter wheel to grind a relatively small part between centers & circumventing the tailstock. Hey, maybe a repurposed Chinese mini lathe + bench grinder dedicated to this grinding task c/w coolant & keep the mess completely off the 'good' lathe LOL.



			Cam Grinding Machines


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## Lofty76 (Oct 3, 2020)

petertha said:


> Lofty76, that is a nice solution. Just to confirm, are you able to traverse the entire length of stock & the motor clears the tailstock in that setup shown? Is the grinding wheel itself 6" diameter or you just mean nominal grinder size? Do you recall offhand what the motor diameter is? Did you do any upgrades to the bearngs or used as-is? I have a 1/3hp slim motor light duty bench grinder but guessing its still 5" diameter.
> 
> The nice part about spindles is they are slim by comparison & motor can be displaced out of the way via a belt. The Themac spindle is ~ 1.5-2" diameter. But the downside is making an appropriate arbor for a big wheel & probably too high of rpm using kit pulleys. Sourcing an appropriate motor may be the easier problem to solve as long as the rpm matches or could otherwise be controlled.



Hi  Petertha, The motor is 3.5" diameter and only 150 watts, but in the photo is rotating an 8"x 1/4" wheel. Had to use that size wheel in order to clear the crank webs. On stripping the original grinder down, the bearings were found to be SKF and I didn't consider they needed changing as the motor runs virtually silently. The base was originally plastic and replaced by a T6 aluminium version, milled from a solid bar. The only problem I had was with cooling, the motor was not vented and got hot quite quickly, the solution for this was to drill a series of 3/8" holes equidistant around each bearing housing end and a fan fitted to the spare wheel spindle end to provide a flow of air. The motor can now work for over an hour without getting more than slightly warm to the touch. However, with such a small motor the cuts have to be very delicate but overall I am extremely pleased with the finish.


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## ajoeiam (Oct 3, 2020)

Lofty76 said:


> Totally agree, Just out of shot in my picture is a whopping great Magnetron magnet directly under the cut and in the coolant flow. It sticks nicely to the bedway and collects pretty much all of the grinding dust.


Sorry - - - - that will collect most (all if you're lucky) the metal bits - - - - it doesn't collect the spent grit from the wheel - - - - there is some you know. 
I was taught to cover up the ways most carefully and then clean up very very carefully after this kind of operation.  
It was quite fascinating to see the setup (and some of the operation) where the 'old timer' in the shop - - - only some 46 years of machining experience at that time - - - he trued up the hard jaws on the lathe chuck.


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## ajoeiam (Oct 3, 2020)

joneb said:


> I know this is a bit crude but it did the job but the method could be used for occasional grinding.



Dunno if its crude - - - - it got the job done and you did it yourself. 
The big advantage that you have doing it yourself is that you can even do three spark out passes (where you're cutting the same each time at your desired setting). That should make for a great surface finish!


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## Lofty76 (Oct 3, 2020)

ajoeiam said:


> Sorry - - - - that will collect most (all if you're lucky) the metal bits - - - - it doesn't collect the spent grit from the wheel - - - - there is some you know.
> I was taught to cover up the ways most carefully and then clean up very very carefully after this kind of operation.
> It was quite fascinating to see the setup (and some of the operation) where the 'old timer' in the shop - - - only some 46 years of machining experience at that time - - - he trued up the hard jaws on the lathe chuck.


 that machine is nearly twenty years old and used nearly every day, I reckon I keep it clean


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## petertha (Oct 9, 2020)

Decent overview of dedicated cylindrical grinder for interest sake.


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## reproturn (Nov 3, 2020)

I rebuilt the spindles on my Waldown C0 toolpost grinder a few months back and was surprised to find that it used two-part magneto bearings (M13 or equivalent). Preload was achieved via an o-ring under the bearing retainer. Bearing adjustemnt was to run the grinder at max speed (around 30,000rpm) a slowly tigthen the retainer till the grinder slowed then back off a fraction. Bingo.
Very little lubrication is required - Waldown recommends ISO32. 
Thought this may be of use if you plan to build your own.


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## ALEX1952 (Nov 3, 2020)

No one has mentioned balancing grinding wheels, which could explain the strange vibration mentioned in an earlier post. This is most important for safety and accuracy, also be very careful not to exceed the rpm limits of the wheel if making your own drive train. balancing units are available but expensive so probably a bit out of our league, however
the aircraft moddeling fraternity  do balance propellors with a very similar piece of equipment, which could probably be utilised for grinding wheels or as a pattern. Forgive me if I'm reiterating what you already know.


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## goldstar31 (Nov 3, 2020)

So far the grinding wheels on the Quorn, the Stent and the Kennet are in balance but
1, They are small
2, They are only running at about 7000 from 1/6th HP 2880rpm motors.

Regards

Norman


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## ALEX1952 (Nov 3, 2020)

It was really a general observation mainly because larger wheels from off hand grinders were being used, another potential problem is lighting, under the right circumstances lights that flicker i.e flourescent can act like a strobe and give the impression of a stationary wheel. We had a very large grinding shop and it did not have florescent lights for this reason, I believe they were sodium.


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## SPOTTER (Dec 26, 2020)

this is my grinder machine, i hope you like it as a project, even if it is to be completed with a protection on the abrasive stone.


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## SmithDoor (Dec 26, 2020)

Most do not know that if angle the compound to about 11° and use compound for feed it will feed to 0.000,1

Dave


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## goldstar31 (Dec 26, 2020)

Dave
             Can you justify your statement with Pythagoras, please? 
I once challenged a similar assertion  and I was met to a LOUD silence. 
I got a book in which (about) 20 degrees is quoted-- and again , Have my doubts.
In the Good old Days, Model Engineer did a Christmas howler of :-

a ladder of 12 feet and a box of 4 feet square  and the question was how far up the wall would the ladder extend if its feet were on the ground and the box was against the wall and the ladder touching the corner of the box.  Of course that has in Pythagorean terms a know hypotenuse but the  cross slide on a lathe  can range anywhere between what the feed screw can extend and retract. 
As a clue( or something) the Morse Taper was designed  for a sine bar in multiples of 5 for the hypotenus. For practical purposes , let us say the sine is/was 10 inches and the infeed was a quarter of an inch. That was the design-- and those at Morse couldn't machine it accurate enough and  NNE of the tapers - now standard- can fit the original design criteria.
Incidentally the box/ladder thing introduces the Binomial theorem - with TWO( and only Two) answers. 
It's better than counting sheep

Happy New Year!

Norman


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## petertha (Dec 26, 2020)

I get something like this: 11 degrees compound angle yields 0.00019" cross bed infeed per 0.001" of compound infeed. So closer to 2-tenths than 1.





for rounder cross bed numbers, just rearrange equation
2-tenth cross bed in-feed per 0.001" of compound infeed, set Angle = ArcTan(0.0002/0.001) = 11.31 deg.
1-tenth cross bed infeed per 0.001" of compound infeed, set Angle = ArcTan(0.0001/0.001) = 5.71 deg.

Whether we can actually achieve this is another matter LOL


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## SmithDoor (Dec 26, 2020)

Petertha has a good drawing.
This was printed in old machinist hand books and tool post grinding manuals

If ever would why on old lathes put the compound at 60° is the would direct reading.

Dave 

View attachment 121665




goldstar31 said:


> Dave
> Can you justify your statement with Pythagoras, please?
> I once challenged a similar assertion  and I was met to a LOUD silence.
> I got a book in which (about) 20 degrees is quoted-- and again , Have my doubts.
> ...


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## SPOTTER (Dec 27, 2020)

In this video we talk about 5.74 °.


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## Asm109 (Dec 27, 2020)

SmithDoor said:


> If ever would why on old lathes put the compound at 60° is the would direct reading.
> 
> Dave


What does this even mean?


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## goldstar31 (Dec 27, 2020)

Asm109 said:


> What does this even mean?


It's a trifle obtuse  but the remaining angle is a useful 30 degrees.


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## SmithDoor (Dec 27, 2020)

On the old lathes the dials where mark for feed.
The turn the compound to 60° the dial will give direct read. 

Dave



Asm109 said:


> What does this even mean?


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## MRA (Dec 28, 2020)

This is an interesting thread.  I was given a 'concrete vibrator' a while ago - an 11000rpm 110v ac/dc brush motor which will run slow on a variac, and which drives the vibrating head by more-or-less a massive speedo cable - 4' long, rubber outer is about 1.5" diameter, spring drive has 1/4" AF square ends.  I have been wondering about making a spindle to mount on the end of it - I have an ER collet chuck on a 25mm cylindrical shaft, maybe I could base it on this.  I have a little tacho too - it's important not to overspeed wheels!  Really like those waterjet ones - wonder where the sheet of abrasive came from.  cheers, M


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## Larry G. (Dec 28, 2020)

MRA said:


> This is an interesting thread.  I was given a 'concrete vibrator' a while ago - an 11000rpm 110v ac/dc brush motor which will run slow on a variac, and which drives the vibrating head by more-or-less a massive speedo cable - 4' long, rubber outer is about 1.5" diameter, spring drive has 1/4" AF square ends.  I have been wondering about making a spindle to mount on the end of it - I have an ER collet chuck on a 25mm cylindrical shaft, maybe I could base it on this.  I have a little tacho too - it's important not to overspeed wheels!  Really like those waterjet ones - wonder where the sheet of abrasive came from.  cheers, M



Sheet of abrasive?  
Bring a wheel of the desired grit, bond, etc. to any local water jet cutter.  They'll cut it like cheese, any size, any shape, preferably round.  
Also check Dan Gelbart's videos on prototypes and precision on Youtube.  His "home-made" lathe and grinder hold one micron and he shows abrasive wheels cut to size and the parent material looking like Swiss cheese.


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## Sleykin (Dec 28, 2020)

I built the tool post grinder that was in Home shop machinist or projects in metal. The motor is a trim router and the belt is on the wheel end of the spindle. this makes for a nice compact unit that mostly eliminates the tailstock issue. I have also acquired a Dumore TPG that has a much higher motor mount than the Themac. I mostly use the TPGs for grinding valves and sharpening hardened cutters of just about any shape.


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## petertha (Dec 28, 2020)

Sleykin - can you elaborate on the flat belt you used: material, dimensions, source... What kind of rpm is that motor spinning?

MRA - the 'sheet of abrasive' posted in my #2 is just a 1/4" wide surface grinding wheel, purchased from KBC. I suspect most machinery/abrasive suppliers will have them.


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## Sleykin (Dec 28, 2020)

petertha said:


> Sleykin - can you elaborate on the flat belt you used: material, dimensions, source... What kind of rpm is that motor spinning?



The flat belt was just a vacuum cleaner belt I just picked one off the rack that looked good and made the wheels to match. The motor is a harbor freight trim router that spins at 25,000 RPM. The pulleys divide that in half and I use a router speed control to adjust lower if needed. I also use the speed control on the Dumor TPG. They work with just about any A/C brushed motor.


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## MRA (Dec 31, 2020)

This has me thinking about bearings now for my hypothetical 25mm spindle with a collet chuck on the end.  I don't suppose they'll take much load, but they need speed so I suppose that means a fair bit of power (torque x speed).  6905 ('normal' option)?  Something fancy like 7905 (angular contact, in pairs)?  Pair of tapers with end load set though a spring washer? I suppose it depends on what happens to clearances when they run that fast.  If you've made one, perhaps you wouldn't mind making a suggestion.


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## goldstar31 (Dec 31, 2020)

Instead of a hypothetical 25MM spindle I have several ACTUAL 25.4mm ones. The 1" diameter cartridge spindles could be swopped about- here there and everywhere with the Quorn, the Stent and the Kennet grinders as prime examples and I added a Geo Thomas small dividing head and now the Potts  milling spindle( referred to elsewhere) Sadly, getting 1"  holders seems impossible in the Uk and I have no idea of whether 'one inch stuff'  is obtainable in other countries.
 Presumably, new starters should simply  bore castings for 25mm and get on with life.  
Having expressed my gripe, there seems to be no reason why a (say) Quorn spindle complete  with high speeds bearings recommended by Chaddock.  They are a 'bugger' to make nd probably the  simpler ones a la Kennet and Stent should not be used.
Of course, the axial bearings suggested for the Quorn are metric but shrouded in a 1"  ethos.
Yer pays yer money and you makes yer choice,

My thoughts, of course

Norman


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## petertha (Dec 31, 2020)

MRA, there's a Workshop Practice Series #27 book called Spindles by Harprit Sandhu that contains a lot of different spindle designs; various OD & length sizes & bearing type/configurations. (My opinion) on the plus side the book is good in that its orientated to the practical hobby machinist. You can pick a drawing, adapt it to your machine & build it from his dimensions. But aside from 'conversational enlightenment', pretty light on engineering details as to why you would select one configuration over another. Mostly I was looking for specific guidance on bearing play setup & adjustment which is probably where the magic happens, but probably also at the expense of bearing life/heat etc. I see commercial spindles with adjustment nuts and wavy washers, but I don't see similar assembly components in the book designs, so I'm not sure what to make of it. Maybe a different path to the desired end result, or? It almost looks like the machining effort is about the same for all the spindle designs in the book +/- intended shaft details like whether it has a taper socket end to match some tooling purpose. Unless you go with uber precision AC bearings, I figure the overall materials cost doesn't vary too much so may as well build the best design - whatever that is.

I'm still on the hunt for a compact spindle design suitable for light but precision grinding using big wheels. There's lots of pictures & videos on the net that show a shiny part. But like the polished potato analogy, that's not the same as hitting a dimension to X decimal places with appropriate finish. I do think there is merit in a standalone spindle driven by external motor because a) you gain independent control of runout vs an integrated motor repurposed from another tool b) it removes a big bulky motor from the working area.


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## petertha (Dec 31, 2020)

goldstar31 said:


> ...Quorn spindle complete  with high speeds bearings recommended by Chaddock...



Are you aware of any drawings and associated component specifications that one could properly replicate these designs? I'm not interested in castings or kits, just the information. And specific to grinding, not milling or general purpose.


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## goldstar31 (Dec 31, 2020)

petertha said:


> Are you aware of any drawings and associated component specifications that one could properly replicate these designs? I'm not interested in castings or kits, just the information. And specific to grinding, not milling or general purpose.


I have the Harprete book but have never read it The reason is that  I've done my spindles earlier!
So  there is the Quorn Book by Dennis Chaddock which gives the 'words and music; for the 1' spindle  but the  main stuff- whilst it is perfectly usable and I have my Quorn  from that.

What might be of use is to get the Bonelle drawings from the net for free- and maybe join the Quorn group as well. Currently, they are discussing  Belleville washers for spindles but I must advise that I 
have no comments good or otherwise for that. However some of the contributors have been at the tool and cutter game for almost as long or longer.  There is a wealth of first class experience which might help you

Best Wishes

Norman


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## Jerr46 (Jan 1, 2021)

I am building Ron Colonna’s 1/4 scale offy and it calls for a 14.5 degree 48DP gear train. I am having trouble finding this size gear cutter. Is there a metric size gear cutters that would work? or does anyone know where I may able to purchase already made gears. Any help on this would be great.Thanks


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## Asm109 (Jan 1, 2021)

Precision and Commercial 48 Pitch Spur Gears | SDP/SI (sdp-si.com) 
Spur Gears & Ratchet Gears | WM Berg 

You can use 20 degree pressure angles in place of 14.5 degree.  You can't intermix them tho.

Metric gears you might find something that is close but you will probably need to tweak your design to change shaft center distances to compensate for the differences in pitch diameter.


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## MRA (Jan 2, 2021)

'Helichron' is good on this - I am working up to cutting some Boxford change gears this way









						Gear Cutting with a Homemade Gear Cutter
					

gear Cutting can be easier than you might think. This is a complete guide for simple spur gears with a homemade gear cutter



					www.helicron.net
				




By the way, I think we are in a tangent on this thread!


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## L98fiero (Jan 5, 2021)

Sleykin said:


> I have also acquired a Dumore TPG


I've also acquired a Dumore TPG, model 57-031, but it has only 2 pulleys, a #1 and a #3 and I don't know if they are even the correct ones for this machine, does anyone have the proper sizes for this TPG?


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## trlvn (Jan 5, 2021)

Dumore has some resources for repair parts:





__





						Tool Post Grinder Replacement Parts | Dumore Series 57 Tool Post Grinder
					






					www.dumoretools.com
				




Craig from Oakville, ON


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## L98fiero (Jan 5, 2021)

trlvn said:


> Dumore has some resources for repair parts:
> Craig from Oakville, ON


Thanks Craig, I already have that but I was looking for the sizes so I could make them. I have a friend with the capability to balance them so it's just a matter of machining if I can get the OD sizes.


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## Brian Rupnow (Jan 5, 2021)

I very seldom have a use for a toolpost mounted grinder.---but---Every time I machine i.c. valves for one of my small engine projects, I wish I had a grinder to finish the contact face on the valves. I get by using a sharp cutting tool, but under high magnification the resulting surface always looks a bit like the surface of the moon. Lapping the valve into the seat cleans the valve and the seat up sufficiently to make them seal, but I do wish I had a grinder for finishing the valve faces.---Brian


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## Sleykin (Jan 5, 2021)

L98fiero said:


> Thanks Craig, I already have that but I was looking for the sizes so I could make them. I have a friend with the capability to balance them so it's just a matter of machining if I can get the OD sizes.


If you look at the list of parts in that link it lists the pulleys (62-68) by size starting with a .75" pulley and going up to the 5" pulley. I would go with what pulleys you have and add a router speed control. As long as you can get the high end with the pulleys you have the speed control should fill in the blanks nicely. You do loose some power over the correct pulley, you don't need much power for the grinding.


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## Sleykin (Jan 5, 2021)

Brian Rupnow said:


> I very seldom have a use for a toolpost mounted grinder.---but---Every time I machine i.c. valves for one of my small engine projects, I wish I had a grinder to finish the contact face on the valves. I get by using a sharp cutting tool, but under high magnification the resulting surface always looks a bit like the surface of the moon. Lapping the valve into the seat cleans the valve and the seat up sufficiently to make them seal, but I do wish I had a grinder for finishing the valve faces.---Brian


I built my first TPG and then traded a milling attachment for the Dumore. My first thought was also finishing and facing valves. Then, once I had one I found lots of other uses for it in finishing hardened pieces, like punches and dies or reamers. I have made several reamers that I turned on the lathe to get the shape then milled flutes. I hardened them and the ground the cutting edge and relief with the TPG. The TPG I built was made from billet aluminum and a piece of plate. The parts were made with a bandsaw and I used a wood router to make the edges rounded. Then the holes were bored on the lathe. Guarantees your spindle is on center-line of your lathe.


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