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Grinding operations on lathe?

peterson

Aluminum
Joined
Apr 29, 2009
Location
Eugene, Oregon
I have conflicting data for grinding operations on a lathe. HTRAL 1915 states that grinding should never be done on a lathe, because no matter how careful you are, some grinding media will end up in the bearings.

This conflicts with a plethora of tool post grinding units I have seen.

Is this simply a matter of choice in how the machine is used? Or has technology changed a bit since 1915, making grinding a reasonable thing to do on a lathe? Perhaps newer lathes have bearings that are sealed, or impervious to grit?

Thanks for your time.
Tom
 
"I always do" and "I never do" are signatures of limited minds.

Common sense "Rules".

Grit is worse for plain bearings than ball and roller.
Think of the bearings in the front spindels on any car.
They see a lifetime of grit, in the day asbestos too!
Either way steps can be taken to reduce grit infiltrating your bearings.
The "real lathe killer" is abrasive strip hand working of diameters.
This is by far the worst thing for any lathe, and unfortunately
the most frequent abuse. When absolutely necessary, cover the ways
with a soiled apron or heavy cloth before useing abrasive strips.

Better to learn to anticipate semi and finnish cut-chip-loads so
you can hit your dimention on the head.

Cheers
M1m
 
Grit is worse for plain bearings than ball and roller.

Plain bearings here. Would also explain the advice in HTRAL 1915 ed., as I suspect roller bearings in lathes are post WWII. Suspect, I say.


Either way steps can be taken to reduce grit infiltrating your bearings.

If you've the time, would you mind detailing these steps? Plastic sheets? Oil flush after the operation? Disassembly?

The "real lathe killer" is abrasive strip hand working of diameters.
This is by far the worst thing for any lathe, and unfortunately
the most frequent abuse. When absolutely necessary, cover the ways
with a soiled apron or heavy cloth before useing abrasive strips.
Better to learn to anticipate semi and finnish cut-chip-loads so
you can hit your dimention on the head.

And this is what I was looking for. Thanks machine1medic.

Regards,
Tom

ps. Very funny Finegrain. = )
 
If you've the time, would you mind detailing these steps? Plastic sheets? Oil flush after the operation? Disassembly?

Get a bag of ?? batting ?? the fluffy stuff the woman's use
to make pillows, stuff rag dolls, and make other soft dreamy stuff with.

Rip off a long hunk spray with W-D or favorite spray product...LPS etc.
wrap around your spindle behind the chuck and duct-tape or somehow
get it to stay put.

Trow away when done...... or light on fire and drive mosquitoes away.

Cheers
M1M
 
Better to learn to anticipate semi and finnish cut-chip-loads so
you can hit your dimention on the head.

Cheers
M1m

I've been thinking about it a bit. This is the way to go, for me. It's what Machinery's Handbook is for, right? = )

As you said though, the situation at hand determines your response. Best to have tools available to provide options for when things go wrong. Cotton batting would never have occured to me. Thanks, M1m.

regards,
Tom
 
Grinding and metal working machines should be in separate rooms. Grinders are designed with bed ways covered and bearings set deep and still dust gets in. Metal working machines are designed with much exposed for ease of oiling and cleaning and will be quickly destroyed by grinding dust. Even the bench grinder should be set far from the lathe or mill. Grit turns into grinding/lapping compound when it gets into oil and eats away until a machine is scrap.
If one grinds in a lath chuck a heavy blanket should cover the bed and carriage with the very minimum of lathe parts exposed. Then a good cleaning made before any handle is turned. Same blanket after washing it should be use when polishing work with abrasive paper.
 
It's not so much the bearings in the machine you have to worry about,it's you bed ways and cross slide ways.People do it all the time and some times you have no choice.As other posted make sure to protect as much as you can,I even go as far as to make sure the lathe is clean and dry (NO OIL) before I start grinding.Oil on the ways is like a magnet to grinding grit and turns into 400 grit lapping compound on your cast iron ways.

I wish I could show you a Webb lathe we do all of our grinding of ceramic on...it isn't fit for anything else any more.Turds who could careless about the machine couldn't be bothered to cover and protect it,now it's only fit for shit work.
If you only doing a small amount of grinding it isn't so bad,if you make a LOT of grinding dust the only way to insure your machine is clean is to remove cross slide and clean it well the put back together.
Move to carriage back and forth cleaning and oiling to you feel NO grit what so ever..then do it some more.
I installed new way wippers on the machine I mentioned above to combat the grit but I think it just made it worse because grit still gets in but now with the wippers in place it just helps keep it trapped in there.

If I were making the call i would get a quote for someone with the right equipment to do the finish grinding.
One last thing,CBN and ceramic inserts can be your best friend dealing with hardened material,you can hit a size and finish that in a lot of cases are good enough.If your talking hitting tenths on tolerance with hard material it's best to be done on the proper equipment,the time saved could make up the difference on money by the time you dick around with a TP grinder and the issues with grit on your lathe.
 
A few notes:-

If your lathe is an SB, Myford, Atl&s, etc, it's probably a jack of all trades. Using it for grinding is far more likely than the prospect of owning a cylindrical grinder. (Nick Mueller excepted :D).

Total-loss bearings have nothing to fear from grinding grit. A catchplate or faceplate with some duct tape over the holes will shield other types of bearings from harm.

Oiled, close-weave cloth (old cotton shirts etc.) carefully laid out to cover the bed, fastened to the bed and saddle with some magnets works very well to arrest and trap the grit. Multiple layers of oiled paper can work, but are prone to crumpling and burn-through. Aluminium foil is more trouble than it's worth, since it burns through very quickly with no liquid to absorb the heat.

Careful removal of the cloths and a good clean up afterwards will remove almost all of the contamination. If a lot of grinding is being done, a strip down and clean gives good reassurance. Cleaning the lathe before doing any toolpost grinding makes the afterwards cleaning much easier.

This is from my personal experience. others may differ.
 
Consider it just an opportunity to acquire another useful tool!

An industrial size tool and cutter grinder (Cincy or Norton #2 or similar) can still earn its keep in a small shop, since they are almost given away. But they are much better make-do cylindrical grinders than a lathe, and are even better configured for doing tapers. OTOH, you have to rig up your own leadscrew on the fixture if thread grinding is the order. Even there, though, the T & C is better configured for mist coolant, and the larger wheel than most toolpost grinders for small lathes can carry is more effective & should require less dressing.

:)

smt
 
I worked in a shop on a LeBlond Regal 13" lathe. We had to grind several rubber rollers of printing presses. Cleanup was a disaster. There was red rubber dust everywhere. Even using a large shop vac while doing the job didn't control the dust and "nubbies". I can imagine steel grinding would be worse. We had red slime coming out of the ways for days after cleaning, but the boss wouldn't allow it to be disassembled for cleaning.
 
some people use and abuse they equipment they have and then buy new machines after 10 or 20 years.
.
others seem to want to better treat their equipment like it will last almost forever and be like new 20 years later assuming it does not get damaged just getting rusty sitting in a high humidity area.
.
it all depends on what way you want to treat your equipment
 
You know, now that I think about it, my boss used to tell management he needed to replace old machinery, get the new one, and take the old one home to HIS shop!
 
Interesting that I ran across this. I was on another forum this morning and a fella posted the following comments and picture. I just went "wow", but I know nothing about it.

schaudtcykindricalgrinder.jpg

Schaudt Cylindrical Grinder.....defines precision
I have spent 280 hours in the last six weeks hand scraping ways, building spindles,bot wheelhead and workhead, and making electronic upgrades to a Schaudt Cylindrical Grinder. The client makes cigarette machines that produce 24000 cigarettes a minute and inspects every one. The grinder finishes components for these machines and must have superior accuracy.

She has .000039" resolution and repeats .000020" after a one hour warm-up cycle.
 








 
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