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1937 Chief
01-13-2017, 11:19 PM
I need to cut a timkem bearing race to fit a special application. I need to cut only 1/2 of the shell, so I can hold it in my chuck. Has anyone had any success cutting a hardened bearing with a carbide tool? I need to remove a .200. I have a tool post grinder, but it will take forever to remove that much. Any thoughts? Stan

Willy
01-13-2017, 11:25 PM
No experience cutting bearing races with carbide. What about using a zip wheel on a die grinder to rough cut the race while in the lathe and then using the tool post grinder to do the finish passes.
I shouldn't have to mention protecting the lathe from abrasives but I will.

BCRider
01-13-2017, 11:31 PM
I need to remove a .200.

Is that a typo? Removing .1 off the wall of just about any bearing other than the larger sizes up around 4 inch OD and over would see you either leaving the wall VERY thin and prone to distortion or would cut through the thinner portion of the inner race. through the wall and into the balls inside.

You won't be able to hold it directly because the jaws of a chuck would badly distort the ring. So you would need to turn a holder of some form which allows you to press fit the portion you don't need to turn down into a recess. The recess will ensure that the outer race stays round and will hold it very nicely.

Not a clue about how well it would machine. But if you have some cheap smaller scrap bearing kicking around have a go at it with whatever carbide tooling you have.

tuckoon
01-13-2017, 11:42 PM
I need to cut a timkem bearing race to fit a special application. I need to cut only 1/2 of the shell, so I can hold it in my chuck. Has anyone had any success cutting a hardened bearing with a carbide tool? I need to remove a .200. I have a tool post grinder, but it will take forever to remove that much. Any thoughts? Stan

Hey Stan, I have had very good success cutting ball bearing external races by mounting a 4 or 4 1/2 " angle grinder on the toolpost and using 1/16" X 4" cutoff wheels on the grinder. On 1"-2" od bearing with a bolt, nut and large washer to to act as a mandril and keep the bearing from rotating and running the lathe at 150-200 rpm then feeding the grinder by hand you are thru the bearing shell in less than a minute. I use a mist coolant and paper towels over the bed and carriage to keep it all contained and clean. Learned this from an old smith in the 60's and he used a kids squirt gun for his coolant. The interesting part to this is with a bit of care the bearings suffer no damage other than being made shorter for special applications when the proper sized parts were not readily available.
steve

ahidley
01-14-2017, 01:03 AM
Just Chuck it up and cut it gently with a carbide cutter. Works fine. I just cut a groove for a retaining ring in the center of a double row bearing. Easy. I touched up the carbide cutter a few times with a diamond wheel because I didn't want to generate any heat into the race. Worked fine. I put masking tape on the sides of the bearing to keep the chips out. This bearing was for the mainshaft on an old vw transaxle.

craigd
01-14-2017, 01:10 AM
I've cut bearing races. It takes a bit of playing around, but not really a big deal. Keep everything as short and stiff as possible. Use a keen tool, small tip radius (don't expect it to last very long). The chips are tiny blue curls, almost like dust.
The suggestions above no doubt work fine, but there is nothing wrong with you original idea.

jhovel
01-14-2017, 06:49 AM
OK. This is something I've done a fair bit of - very successfully. I use a ceramic tip, not TC. Never got a useable finish with any TC tips, whereas the ceramic tips don't even look like they are working hard. Nice finish, accurate dimensions and all the heat goes into the chips. Ceramic tips are about the same price as TC tips. Be VERY careful NOT to do any interrupted cuts with them. They will chip on the first rotation. :)
BTW, I like using ceramic tips a lot. They allow much faster removal of material without generating much heat - it all seems to go into the chips. This is on a hobby lathe, not some multi-ton machining centre (that they were designed for of course).

dian
01-14-2017, 07:19 AM
"Ceramic tips are about the same price as TC tips."

really? would you mind sharing where you get them?

Magicniner
01-14-2017, 07:51 AM
"Ceramic tips are about the same price as TC tips."

really? would you mind sharing where you get them?

I found a box on eBay NOS that were cheaper than my average TC tips of the same size, it's too boring for many but if you check the auction sites regularly for what you want it sometimes comes up ;-)

- Nick

Spin Doctor
01-14-2017, 09:49 AM
In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.

wmgeorge
01-14-2017, 10:20 AM
In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.

Amazing what you can learn with an open mind. A lot better than a typo, thanks for posting.

MattiJ
01-14-2017, 11:15 AM
In the past I've cut down Timken cups to use them for other purposes. The best thing I found was CBN (cubic boron nitride) inserts. Not cheap and they do not like interrupted cuts at all. But they'll cut bearing races like butter.
What size lathe you used?
Does anyone with experience how CBN inserts work on a smallish home lathe?

I have used random carbide inserts to do it couple of times but the inserts are gone pretty fast. 1 usd insert used per bearing is still better than grinding with my equipment.

DR
01-14-2017, 11:42 AM
It's called "hard turning". Usually done on rigid, commercial grade machines with expensive tipped inserts.

1937 Chief
01-14-2017, 12:07 PM
I have a 13 inch old south bend. Very well built. Thanks for the answers I will do a practice cut on a old race. Looks like it's possible. I have a 61 Triumph TR5AC. It seams to be a little different than other models. This bearing is for the fork steering. Stan

ikdor
01-14-2017, 12:42 PM
I was surprised to find ceramic inserts at aliexpress for indeed the same price as the carbide inserts. Haven't tried them yet though on anything.

dian
01-14-2017, 12:58 PM
go try them on a hardened pin and tell us what happens. i just had a look and the stuff (e.g. 10 for $17) doesnt look like ceramic to me, neither do the others. if you search for ceramic most of what comes up is carbide, so i reckon it might just be a linguistical misunderstanding. remember though, you have to go really fast, at least 1000 ft/min with ceramics, they kind of melt the work away.

MattiJ
01-14-2017, 01:04 PM
go try them on a hardened pin and tell us what happens. i just had a look and the stuff (e.g. 10 for $17) doesnt look like ceramic to me, neither do the others. if you search for ceramic most of what comes up is carbide, so i reckon it might just be a linguistical misunderstanding. remember though, you have to go really fast, at least 1000 ft/min with ceramics, they kind of melt the work away.

Agreed, looks like translation error. And if you search alixprss for ceramic insert you get lot's of hits about "metal ceramic inserts" which is same as "cermet"
Pretty sure sign that if there is a screw hole in a insert its not a ceramic one.

EddyCurr
01-14-2017, 01:07 PM
... remember though, you have to go really fast, at least 1000 ft/min with ceramics, ...This is a detail that has kept me from trying the ceramics, this and the perception about price.

.

ikdor
01-14-2017, 03:47 PM
http://www.sandvik.coromant.com/en-gb/news/press_releases/Pages/Ceramic-insert-for-CoroMill-490.aspx

Seems to be a hole in these, fist hit on google.

ahidley
01-14-2017, 08:51 PM
http://i194.photobucket.com/albums/z80/ahidley/20161003_201121_zpsextagu8o.jpg (http://s194.photobucket.com/user/ahidley/media/20161003_201121_zpsextagu8o.jpg.html)
http://i194.photobucket.com/albums/z80/ahidley/20161003_201121_zpsextagu8o.jpg
Old bearing in background. New bearing with ring groove just cut with harbor freight lathe using a parting bit with carbide insert

http://i194.photobucket.com/albums/z80/ahidley/20161003_200615_zpsxvuydru0.jpg (http://s194.photobucket.com/user/ahidley/media/20161003_200615_zpsxvuydru0.jpg.html)
http://i194.photobucket.com/albums/z80/ahidley/20161003_200615_zpsxvuydru0.jpg
Old bearing in back. New bearing modified with old ring installed. Worked perfect. See my previous post
I also will add that others have the correct fact that interupted cuts didnt go well. interrupted cuts, i.e. just stopping the cut would break off the insert, requiring a touch up to continue.
Pretty simple, Took an hour.
Yea I know there are less balls on the replacement bearing. I was told it was discontinued and this was the closeest replacement available. Customer got what he wanted and transaxle was reassembled with new bearing...........

Hopefuldave
01-15-2017, 06:04 AM
This has piqued my interest, so I've just EvilBayed some Iscar TPGN 160304 KT30 ceramic inserts, new old stock, box of 10 for 5 + postage, so roughly an US dollar each, they're for hardened steels etc. and I have some bearing races I'd like to turn down too (was planning to spend hours grinding them) - when I get the Tuits I'll try 'em out and report back, may be a while though! If anyone has Useful Advice on their use I'd be pleased to hear it!

1000 fpm on a 3" diameter bearing works out at 1300 RPM or so, can do that or nearly twice, lathe's reasonably rigid (damn well ought to be, the weight of it!), recommendations re coolant? Like carbide either flood or none to prevent thermal shock is my guess (and it is a guess...).

Dave H. (the other one)

ahidley
01-15-2017, 01:50 PM
The term ceramic kinda annoys me. Then I found ceramet and what ceramic bits really are is ceramic and metal mixed. Kinda like a diamond wheel. The diamond needs a way to attach to the tool so they use nickle or some metal to electro plate the diamond chips together and adhere to the base. For a simple explanation its the glue. Ceramic works the same but with a different manufacturing process. Ceramic inserts look just like carbide inserts but with a different tint in color. They can be touched up, sharpened, just like a carbide one by using a diamond wheel. All the ones that I've used did not chip as easily as carbide did and lasted about 5-10 times longer between touchups. So because they lasted so much longer than carbide and cost only slightly more they are cheaper to use.
As for speeds and feeds I've just been using the same as carbide and seemed to be fine.

MattiJ
01-15-2017, 03:00 PM
The term ceramic kinda annoys me. Then I found ceramet and what ceramic bits really are is ceramic and metal mixed. Kinda like a diamond wheel. The diamond needs a way to attach to the tool so they use nickle or some metal to electro plate the diamond chips together and adhere to the base. For a simple explanation its the glue. Ceramic works the same but with a different manufacturing process. Ceramic inserts look just like carbide inserts but with a different tint in color. They can be touched up, sharpened, just like a carbide one by using a diamond wheel. All the ones that I've used did not chip as easily as carbide did and lasted about 5-10 times longer between touchups. So because they lasted so much longer than carbide and cost only slightly more they are cheaper to use.
As for speeds and feeds I've just been using the same as carbide and seemed to be fine.

Cermet is kind of similar to carbide, rather heavy, usually? slightly magnetic and metallic looking. But there is also pure ceramic inserts, ceramic inserts reinforced with another type of ceramic whiskers and so on.
I have some that look like these:
http://www.sccarbide.com/images/slider/ceramic_2000x719-01.jpg
You'll notice the difference in weight immediately in a hand compared to carbide.

dian
01-15-2017, 03:16 PM
its rather simple, the "ceramic" is aluminum oxide and the fibres (if any) are silicum carbide. kind of a mixed grinding wheel compacted. sc because it has a high modulus.

ahidley
01-15-2017, 07:36 PM
MattiJ. High speed steel can be razor sharp. Carbide close but not razor because its brittle. With hss you can take very light cuts. Carbide doesn't really like tiny cuts.
How does the full ceramic work? Is it razor sharp? Does the edge snap off easy? How does it work on light cuts, I.e. .0005-.001?? How does a diamond wheel grind it?

Spin Doctor
01-15-2017, 07:53 PM
What size lathe you used?
Does anyone with experience how CBN inserts work on a smallish home lathe?

I have used random carbide inserts to do it couple of times but the inserts are gone pretty fast. 1 usd insert used per bearing is still better than grinding with my equipment.


Hardinge HLV in an oversize collet. Had to make various size compression rings for piston rings. The only reason I had the inserts is we used them on stellite valve seats and when they went to different inserts on production the Tool Room was sent the surplus

MattiJ
01-16-2017, 12:09 AM
MattiJ. High speed steel can be razor sharp. Carbide close but not razor because its brittle. With hss you can take very light cuts. Carbide doesn't really like tiny cuts.
How does the full ceramic work? Is it razor sharp? Does the edge snap off easy? How does it work on light cuts, I.e. .0005-.001?? How does a diamond wheel grind it?

Ceramics i have seen are not sharp, there is a tiny rounding on edges that you can probably see even in the above photo.
And carbide: try the honed dcgt inserts some day. Pretty damn sharp and will happily shave of that last 0,02mm in 1018. Smallest cuts i have taken with dcgt inserts were somethin like 0,005mm off from diameter but getting any consistency is trickey. Chips were like very fine pile of dust.

ahidley
01-16-2017, 12:37 AM
Well worth the time to read about ceramic vs carbide.http://www.mmsonline.com/articles/successful-application-of-ceramic-inserts
My home shop will not venture into this route. But I will continue to use ceramet inserts.....
Thanks

krutch
01-16-2017, 04:04 PM
Chief,
I would be wary of altering the steering on any motorcycle. You could get away with it but then again, it could just kill ya. I have not gotten it in my mind if you are making the race shorter or smaller in diameter. Any material off the dia. could change the shape of the bearing surface. You don't want an egg shaped roller race. If you are shortening the race, the rollers might not run on the race as designed. Either condition could cause a loss of control while ridding.
The designers had a reason to make those bikes as they did. Just saying.

Jaakko Fagerlund
01-16-2017, 04:28 PM
Regarding the turning speed of ceramic inserts, it is best to consult the manufacturers data sheet and not just blindly go with 1000 ft/min surface speed. The Kennametal inserts we have like 100 m/min, so roughly 300 ft/min on 55 HRC (ie case hardened) steel. Faster if there is interrupts as it needs to keep the heat production up to work. Basically you will want a fireworks show from that insert.

And no coolant ever on a ceramic insert, as it will shatter instantly and not remove any material as it doesn't work as supposed to.

But, carbide works just fine on hardened stuff, just needs to go slow (the harder the material, the slower you have to go). Just today I parted off deeply case-hardened guide pins, 24 mm in diameter with a 1.5 mm thick layer of hard on them. I had 3 mm wide cut-off insert, 400 RPM (works out to 30 m/min, so HSS speed) with coolant and slow feed and parting off near the jaws. No problems, happy blue chip curled away until through the case and the soft stuff inside is like butter.

MattiJ
01-19-2017, 02:54 PM
Had a box of used VNM-something ceramic inserts lurking around so had to give them a try.
Most of them were chipped so I grind the cutting edge on a 600 grit lapidary? diamond wheel and honed it very quickly with 2.5 micron diamond paste.

First try on crappy cheese 1018 and I have to say I am impressed:
http://i.imgur.com/AfMg4O0.jpg

Change to topic and hard turning bearing race:
http://i.imgur.com/ICyXV0A.jpg

Somehow very unrealistic feeling when the insert is cutting hardened bearing race like its made of butter ;)

https://youtu.be/YgkBLKKC54o?t=70