Need help finding a centerless grinding shop for small parts

DPM · Mar 26, 2021

I have 2 little straight pins that need to get centerless ground down to size on the OD.
One is .040 +/- .0002 and the other is .0625 +/- .0002
Both parts are made from 303 SS and OAL = .525
We run them a little oversize on our Swiss to somewhere around .004/.005 oversize on the OD.
Qty = 750

Some say grind the bar down to size and run it, but we can't run bar that small in our machines.
Some say you should be able to hold that tolerance on a Swiss, but it just doesn't happen on these jobs.

I'm in so California and can't find a grinder who can confidently quote or do the job.

Can anyone provide info on shops that specialize or can easily do this type of work. Someone that you have first hand experience with is ideal.

Any input is greatly appreciated.

Thanks.

Guest · Mar 26, 2021

First thing you need to list your city. I used to live in Riverside, the two grinding shops I used there are now out of business, no help from me, sorry. For some reason grinding shops aren't good at advertising, and a business people don't frequently use needs to be.

DPM · Mar 26, 2021

I'm in Pomona, but location isn't critical. I'll go out of state if I have to. Just need a shop that can do good work.

michiganbuck · Mar 26, 2021

And add the length
A simple Harig Unison Dedtru can do great work of close centerless like work with only a surface grinder.

Wow, I can't find any for sale...darn

Oh, and OAL = .525

john.k · Mar 26, 2021

I have scrapped a very nice low hour Cincinnatti Filmatic #2 last week ,with hydraulic wheel and regulating wheel form dressing,and lots of accessories including a long bar fixture .......simply no work for it,no resale above scrap ......great shame.

david n · Mar 26, 2021

State of the art place...... not cheap

Centerless Grinding Services Near Me | Bar & OD grinding | Minnesota Grinding Inc.

michiganbuck · Mar 27, 2021

Here is the unison Dedtru. It simply mounts on the surface grinder and can hold +- .0002.

You don’t need the Harig through collum SG if doing shorter work.

UNISON DedTru(R) Centerless Grinding Fixture | FlexMech Engineering
Unison Corporation - Products

Guest · Mar 27, 2021

david n said:
State of the art place...... not cheap

Centerless Grinding Services Near Me | Bar & OD grinding | Minnesota Grinding Inc.

It lists their minimum diameter as .050, that might be the OP's problem finding a grinder, his parts are smaller than that.

Guest · Mar 27, 2021

DPM said:
I have 2 little straight pins that need to get centerless ground down to size on the OD.
One is .040 +/- .0002 and the other is .0625 +/- .0002
Both parts are made from 303 SS and OAL = .525
We run them a little oversize on our Swiss to somewhere around .004/.005 oversize on the OD.
Qty = 750

Some say grind the bar down to size and run it, but we can't run bar that small in our machines.
Some say you should be able to hold that tolerance on a Swiss, but it just doesn't happen on these jobs.

I'm in so California and can't find a grinder who can confidently quote or do the job.

Can anyone provide info on shops that specialize or can easily do this type of work. Someone that you have first hand experience with is ideal.

Any input is greatly appreciated.

Thanks.

What Swiss can't run 1/16" stock? What is the smallest you can run? What type material? A Swiss between 12mm-20mm should be able to hold +/-.0002 if you have ground stock, good revolving bushing bearings, and a guide bushing in nice shape. It is starting to appear most grind shops don't do work as small as yours.
It might be time to get an indicating micrometer, refurbish your machine and run them yourself. I worked in plenty a Swiss shop where we ran jobs with those O.D. tolerances on them and not in brass either. We did 100% all the parts for diameter and it was a one on one job, as in the operator only ran that machine.

john.k · Mar 27, 2021

On my centreless ,the operator used thumb and finger to grind small stuff....tips of the fingers were always pink in contrast to the greasy black of the rest of the hand.....Unless the part is one diameter for thru feed,you need to make a dedicated picker /placer....not easy in a part that has no centres to grip.

CarbideBob · Mar 27, 2021

Dualkit said:
It lists their minimum diameter as .050, that might be the OP's problem finding a grinder, his parts are smaller than that.

Yes you'd want a small centerless like a Royal.
Parts a bit small for a Cinci even the smallest machines.
DedTru and Tru-Tech work but not very fast machines/fixtures. Expensive fixtures and have a niche.
At one time you could not throw a dead cat down a industrial street in SE Michigan without hitting a shop that could do this work.
Now it is very rare indeed.
OP says 750 pieces but not total estimated yearly buy level. I would include that with any RFQ.
750 a day, week, month or year will attack different attention as grind cycle times here are going to be measured in seconds.
Bob

Conrad Hoffman · Mar 27, 2021

These people are probably the best in the world at what they do, and reasonably priced. Yes, not in the USA, but it's not really a big problem.
精密シャフト、ニードル、コロ｜三和ニードルベアリング株式会社

tdmidget · Mar 27, 2021

Definitely a job for Royal Master.The one I ran would easily hold your tolerance. It had .00001 graduations. There is a substantial learning curve and I have no idea what they bring.
ROYAL MASTER - Used Machines | Machine Hub

triumph406 · Mar 28, 2021

Deltronic will quote your parts. I've had them quote centerless grinding for me in the past.

All Diameter Grinding (Orange) screwed me on a job, so I wouldn't use them again.

Guest · Mar 28, 2021

triumph406 said:
Deltronic will quote your parts. I've had them quote centerless grinding for me in the past.

All Diameter Grinding (Orange) screwed me on a job, so I wouldn't use them again.

I didn't know Deltronic also did job shop work. I used to work in the OC decades ago, All Diameter rings a bell, I think they have been around a while.
I think they ground clear plastic bars for us that we ran lots of.

triumph406 · Mar 28, 2021

This is the contact info I got from the last quote from Deltronic

Tracey Dickerson
HI-precision grinding
Div of Deltronic Corporation
3900 W. Segerstrom Avenue
Santa Ana, CA 92704

Tel: 714-545-5800
Fax: 714-545-9548

[email protected]
Deltronic | HI-precision grinding |
Aerospace-Military-Medical Job Shop

DPM · Mar 28, 2021

Have tried All Diameter and had mixed results. Had Deltronic quote it a while back. Price was ridiculous. Basically priced so they wouldn't get the job.

DPM · Mar 29, 2021

Doug said:
Just looked at Boston Centerless website, they supply pre-ground bars down to .040" diameter. At one time I had a cam swiss, but easier to buy lengths of bars and part off to length in bar fed CNC lathe rather than trying to meet diameter tolerances in the swiss.

That's how we used to do it when we had our cam machines. We'd put on a small diameter feed tube and let the machine go. Just had to watch out for collet/bushing marks.

Our CNC Swiss bar feeder channels are too big for stock under 3/32 and can't justify costs to purchase channels, pusher, and spindle liner for the job otherwise that would be the way to go.

Funny thing is there are shops that will grind a bar down to .040 but they just won't do parts.

Need help finding a centerless grinding shop for small parts

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