Wide Open RFQ For The Group

Brazz?

==================== If they are not at the size limit of the ER8 collet, would they consider a split bushing? I envision something like a top hat possibly made of urethane (which might not need to be split) Delrin should also be good but most likely would require splitting.

May even be a "stock" item somewhere.

What is the size of the steel stock?

ER8 maxes out around 5mm. If the stock is significantly smaller than that a simple brass sleeve may do the trick depending on necessary holding force. I have made brass bushings for end mills and noted that an ER 16 collet compresses them around a piece more than you might think. An ER8 spindle nut and collet may not be capable of as much force, but the principal may be similar. If that is not adequate holding force then a simple sleeve with some slits cut in it may be adequate. A sleeve can be turned and reamed easily on any fair lathe, and slits can be cut a number of different ways. The only really important cut is that the inside and outside are concentric.

If on the other hand your stock is close to 5mm then a special brass collet may be required as you have requested in your original post.

Why not wrap the part with a piece of Mylar film before inserting in the collet? That ought to work, hold securely but not mark the part. Probably will work even better than brass.

Jon

Or, if mylar makes for too much flex, brass shim stock.

Hey Joe -- how are you liking all the content-free advise! I'd be happy to help your customer out if they need some algorithms or circuits designed, but I'm not a real machinist.

Something strange here. This is exactly what the ER collets were developed for. Has the customer tried using a new good quality [no burr / clear] ER collet in the correct size? Unless grossly overtightened it should not mark a steel device unless it is dead soft.

Have you tried having a standard collet electropolished/electrodeburred?

Greetings Joe, I'm surprised that standard ER collets are marking thier parts. But let us say that the parts are being marked. I will bid this job but I need to know a little more. Especially about finish, accuracy, and liability. Finish is probably the most important if the collets need to be sterilized. Anyway, I would be interested in quoting this job if a few more particulars could be had. Thanks, Eric Snow, E T Precision Machine

I'm simply replying to the latest post to cover my bases here...

They require the braSS or bronze or similar collets.

Yes, a sleeve would work, but this is medical and they requested it sleeveless.

Yes, ER collets are designed to not mark. However, this is medial and they requested braSS, etc...

...Did I miss anything?

Happy Friday!!!

I'm sorry I missed this thread, Joe, but I assume you're aware that brass lathe collets are available off-the-shelf. These are sometimes called "emergency collets," which applies to any soft collet that has to be machined to fit a certain part.

I'd be surprised if such collets aren't available for whatever you're looking for. As I said, I missed the beginning.

Joe, there is one parameter you have not supplied, and perhaps the customer never supplied. That is: how much torque will be applied between the spindle and the steel device?

The friction between a brass collet and a totally smooth steel device may allow the device to slip in the collet.

Just wondering!

Paul

If they are made, I'll buy them... That would be perfect.

The part is not going to feel any rotationa torque at all. We are spinning while a lazer etches...

Even a hard rubber collet will work.

I see that you want ER8. Maybe, maybe... How about a brass collet bushing that fits in a larger-bore collet? Like this, maybe:

Or call Hardinge. They make all kinds of special collets. Take a look at page 14 of this, "No Scratching Allowed":

Good luck!

A quick Google search shows several vendors for Brass ER8 collets. Don;t know what sort of Certifications they might be able to supply. Found several vendors via Alibaba. You could check with MariTool.com They manufacture many of their parts.

Unfortunately, all of them are simply a poor use fo keywords from what I can tell. ...As in they meant to type "collets for holding brass" and not "collets made of brass" in this case.