What is this center

animal12 · Nov 17, 2021

I was over at a bud's shop yesterday & saw what looks like a small canter sitting on his bench . Looking at it closer it seems to have a thin maybe abrasive part that slips over the steel center & is held on with another part . I'll try to attach some pics .

Any of you ever seen one of these ? If so what are they used for ?
thanks
animal

sfriedberg · Nov 17, 2021

Ask your bud? If I had to guess, I'd guess a center lap, to clean up worn or possibly boogered-up centers on a part.

animal12 · Nov 17, 2021

He doesn't know what they are either , he can't even remember where he got them from . He's a non computer guy too , That's why I got the job of finding out what they are . They have no marking on them either .
thanks
animal

Rob F. · Nov 18, 2021

Could they go in a collet and use the sanding paper as a way to give plenty of grip to drive the part? No heavy cuts that way, but no drive dog to get in the way either.

Milland · Nov 18, 2021

I'd go with center lap too. It looks a little light duty to be a friction driver, although I guess under modest load it would work for that.

Where does your buddy get replacement abrasive cones? Or does he just use up what he has?

michiganbuck · Nov 18, 2021

I would also go with a quick center lap, likely one might find it in a patent search.

crossthread · Nov 18, 2021

The tang is a bit odd for a tailstock mount but from the looks of the part of the cone that is loaded up I agree that it may be used to clean up a wonky center hole. Not sure why you would need this to do that but maybe it is designed to be used on some exotic material that doesn't center drill well. I can't imagine what that would be.

atex57 · Nov 18, 2021

Appears to be a center lap.

Used to clean up a center after heat treatment.

Ed.

michiganbuck · Nov 18, 2021

atex57 said:
Appears to be a center lap.

Used to clean up a center after heat treatment.

Ed.

And a bugged center., to true up a center drill made center to a better circle, and some times to move a center a tenth or a few.

eKretz · Nov 18, 2021

I would say center lap also. Looks like the abrasive paper is placed on the steel center, then the steel sleeve is placed over it and the pins pull it tight when it's twisted to stop the abrasive paper from spinning on the steel (male) center when it contacts the workpiece so it will lap the female center. Looks like it may be shop-made to me.

richard newman · Nov 18, 2021

eKretz said:
Looks like it may be shop-made to me.

Where would one get the abrasive paper cone? Seems like who ever makes the cone would also make the rest of it.

eKretz · Nov 18, 2021

richard newman said:
Where would one get the abrasive paper cone? Seems like who ever makes the cone would also make the rest of it.

You could make them pretty easily yourself. Just don't let the paper overlap. There are a few manufacturers that make these with a solid vitrified tip, or electroplated, etc.

Superior Abrasives for one used to make something similar, don't know if they still do. Theirs had a screw on abrasive paper clamp though, not a twist lock. I still think this one looks shop-made.

Center laps are used to clean up boogered centers, also as mentioned to clean up after heat treatment. As Buck noted already, they can also be used on fresh-cut centers to ensure they're round. An out-of-round center in a part running between dead centers in an OD grinder will almost inevitably produce an out-of round part. A center lap can fix that problem pretty rapidly and easily.

richard newman · Nov 18, 2021

Yeah, I've had experience lapping centers. Did it decades ago to prepare a big woodworking shaper spindle for re-machining at the shop of my precision metalworking mentor. Needed to get the bearing seats to run true on bench centers. He had me turn a 60 degree center from mild steel, then lap with valve lapping compound. Turn center true, lap, carry 50+lb spindle to metrology room, inspect, repeat, repeat, repeat... Took me 2 weeks of late night after hours sessions, got it to within a tenth. A real eye opener for me, had no idea one could do such things

Illinoyance · Nov 18, 2021

+1 on center lap.

animal12 · Nov 18, 2021

Thanks folks , we're going to go with " center lap " .
thanks again
animal

gbent · Nov 21, 2021

eKretz said:
An out-of-round center in a part running between dead centers in an OD grinder will almost inevitably produce an out-of round part. A center lap can fix that problem pretty rapidly and easily.

If you always make sure the round portion of a half center is slightly larger than the center hole in the shaft you will have very few out of round shafts. The typical out of round comes from a non-perfect center hole rotating over the flat on a to-small half center.

eKretz · Nov 21, 2021

gbent said:
If you always make sure the round portion of a half center is slightly larger than the center hole in the shaft you will have very few out of round shafts. The typical out of round comes from a non-perfect center hole rotating over the flat on a to-small half center.

Not necessarily. On very light work I'd say you're mostly correct. Once the work gets to a certain weight it will pull down differently as it rotates and the OD won't be round no matter the center. Heavyweight stuff works a little different.

EmGo · Nov 21, 2021

richard newman said:
Where would one get the abrasive paper cone? Seems like who ever makes the cone would also make the rest of it.

From the Cen-T-Lap company, of course

Precision center lapping apparatus and method - Cen-T-Lap Corp.

No idea if this is one of theirs, I never owned one. And looks like they are gone now, so no chance. But they made and sold abrasive paper cones to go with their machines, claiming it was faster, easier, cheaper to replace the sanding cones than dress a wheel.

SIP6A · Nov 21, 2021

richard newman said:
Where would one get the abrasive paper cone? Seems like who ever makes the cone would also make the rest of it.

1-1/2″ x 60deg Center Lap Cone – Superior Abrasives

It should be obvious to any apprentice boy that the tool is shop made.

gbent · Nov 21, 2021

eKretz said:
Not necessarily. On very light work I'd say you're mostly correct. Once the work gets to a certain weight it will pull down differently as it rotates and the OD won't be round no matter the center. Heavyweight stuff works a little different.

Good point. My OD grinder experience stops about 100#.

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