Using diamond wheels on a tool post grinder?

[rhb]

I can find no mention of the subject with searches, so I'd like to ask here.

The grit from tool post grinding is not good for the lathe which raises the question why not use electroplated diamond wheels instead? For example:

https://www.amazon.com/Diamond-Grinding-Parallel-Tungsten-Ceramic/dp/B09NQ7P6TX

I cite that item just because I saw it in the ads when I tried to find a mention of using diamond wheels in a tool post grinder. It seems to be an obvious improvement. There will still be grit where you don't want it that needs to be cleaned up. But much less.

 

[winger]

Something to do with diamond losing carbon with the high temperatures of grinding. Hand lapping is fine. Try cbn.
Dave

 

[Milland]

As said, diamond is not usually used on steels/irons due to carbon absorption, use CBN instead. You'll still get some dust, but a decent shop vac with HEPA filters will combat that.

 

[Peter from Holland]

One problem is how to dress a diamond or CBN wheel to make it run true
Not so easy

Peter

 

[rhb]

I was not aware that electroplated CBN wheels were available. I found a Norton guide in my library which helped a lot. Only potential issue I see is diameter. I'll have to figure out what I can fit on my 10" swing Clausing. Smallest I've seen so far is 6".

 

[Peter from Holland]

I would think resin bond Not electroplated Thats for toolgrinding Not for OD/ID grinding AFAIK
Resin bond can be dressed with a driven dressing wheel Both nead a sturdy accurate spindle

 

[rhb]

How much do resin bonded wheels shed? I'll happily pay extra to minimize that. No matter how hard you try, some of the stuff escapes to places you don't want it.

 

[michiganbuck]

Diamond wheels don't grind steel very well, and diamond grit is just as bad.
Peter mentioned CBN wheels are difficult to dress.
You might tell how much run out you have.
You might take the chuck apart to see how much clearance there is to the OD of the scroll....and reduce it to .oo2
Might blue up a round stock and see how your jaws are hitting.
Buying a TP grinder is likely as much as a new chuck might cost.

 

[michiganbuck]

Grinding a chuck one should have it clean and tight (the scroll), along with holding the jaws open and tight to the scroll (or screws if an independent).

 

[michiganbuck]

Just about any die grinder and $3.00 worth of wood should make a OK grinder.
Even a horable fright die grinder. The straight nose is best for using a fixture.

Amazon.com : electric die grinder 1/4 shank

3 small C clamps and 12 rubber bands make an OK jaws holding method.

 

[rhb]

The primary task is grinding a small MT 2 taper spindle I" diameter and 7-8" long. Two bearing journals about 3/4" wide. Purpose is to install ABEC 7 angular contact bearings in place of the current taper bearings which have excessive clearances. ABEC 7 tolerances are +0/-0.0002" on the spindle. Have not yet checked the housing bore tolerances as I haven't figured out how to get the bearings out. I can't find my notes right now, but IIRC the spindle is about 6 tenths oversize. Hopefully the bore will be undersize, but if not I plan to plate with electroless nickel and hone or grind back to tolerance.

Chuck jaws are more of a "while I've got it set up" side task. The only other task for I can envision is touching up shop grader ER32 collets.

 

[michiganbuck]

Is there any chance that you can trade lathe work time to someone who has a grinder?
Everything about a lathe contributes to making high-precision work difficult,
along with not being good for the lathe.
A Two bearing shaft and a true running taper should be run between dead centers... It is just about impossible to make a decent bearinged and taper shaft out of the best chuck.
Putting high-precision bearings on a .0002 wobble shaft is poor engineering.
Running a taper between centers allows one to take the part out of the set-up to check it...and then put it back in the machine...and with it having no wobble.

 

[rhb]

Unfortunately, with the demise of the automotive machine shops I went to 50 years ago to get VW crankshafts reground I don't know anyone with the capability of grinding between centers. In fact I only know of a couple of CNC shops within 30 miles of me. There are probably a few more than that, but it's pretty sparse and at least one doesn't take general work. In fact he doesn't even have a sign. He bought a small residential house, gutted the inside, installed a garage door on the side of the house and moved 3-4 CNC machines in.

I wouldn't trust someone who would trade machine time with someone they just met.

I can't imagine expecting anything but dead centers to hold a spindle for grinding.

Initial plan had been to get an estimate of what it would cost for tooling to do it myself as a fallback if the quotes are too high. But I think I'll get quotes sooner rather than later. If I can get it ground for around $100 I'd prefer that. I'm not keen on having a low experience person (me) do it. I'd actually planned on setting up some scrap wrist pins to practice on until I was confident I'd get it right.

 

[rhb]

I just made a bunch of calls. The oldest machine shop in LR suggested another shop that also couldn't grind between centers which suggested a cam grinder.

I didn't get an answer when I called them. Then I saw a yelp review. It was rather incoherent, but it appeared that it took over two weeks to get a warped cylinder head ground with lots of excuses and stalling. Yelp review, so suspect. But it appears that's the only relatively local (75 miles) choice.

 

[CarbideBob]

Why would you want to use a superabrasive (cbn or diamond) wheel for this task over a conventional toolpost grinding wheel?
As far as how much they "shed" I'd be surprised if you lost even a few grains at this amount of stock removal.
Bob

 

[rhb]

To minimize the abrasive dust generated. Maybe I'm mistaken about how much it would generate relative to a superabrasive wheel. I was under the impression that a plated wheel would generate very little abrasive dust.

This is a completely new technique for me as well as the one person I know with a shop. He's got a Dumore, but has never used it. We're not even sure what kind of shape it's in.

We spotted an MT adapter from his Harrison on his Nardini spindle yesterday and found it was only making firm contact for about 1/4" at the mouth of the taper. It's a good fit in his Harrison, though we haven't spotted that. The Nardini is a hobby rebuild project. The predecessor was a 21 x 60 Harrison. Crazy big, but it was free. Some people like old cars, others like old machine tools.

So he's got an inside grinding job and I've got an outside job. His Dumore is too big for my Clausing and his Harrison (both 10" swing). So we'd have to fix the spindle on the Nardini to be able to mount my spindle.

 

[Conrad Hoffman]

I used to use diamond plated tools for ID grinding of ceramics with a Dumore. Not the right choice for steel. You just need to cover and clean the lathe like crazy. Be aware that a toolpost grinder is a really poor substitute for a real ID/OD grinder, but if it's all you've got, it might get the job done.

 

[rhb]

Hi, Conrad,

It doesn't appear I've got a good choice locally to job this out. I read employee and customer reviews of the one grinding shop in Little Rock and they were not encouraging. Though the HR manager rated it 5 stars as a place to work.

Rather fun to run into you here. Time to contact some spindle rebuilders, though I fear they will be too pricey.

Have Fun!
Reg

 

[ClappedOutBport]

People make a bigger deal of it than I think it is. I ground approximately 10 thou off a 24" long shaft 1 3/8" in diameter. I fed towards the tailstock and cleaned the ways each time before going back. I kept a rag under when possible. Way wipers are good. I have yet to see any damage.

 

[Conrad Hoffman]

Hi, Conrad,

It doesn't appear I've got a good choice locally to job this out. I read employee and customer reviews of the one grinding shop in Little Rock and they were not encouraging. Though the HR manager rated it 5 stars as a place to work.

Rather fun to run into you here. Time to contact some spindle rebuilders, though I fear they will be too pricey.

Have Fun!
Reg

Depending on the spindle, it's often possible to DIY it. You just need a clean work area and, often, to make some disassembly/assembly tools.