Securely Holding a Round Part

[jmillard]

I am looking for a good way to securely hold a round part. Because of patents and past experiences using collets, I cannot thread the part into its mating part, I cannot use a collet, and I am getting stuck on how to make this design work.

Currently, we use a collet design, but it does not have the clamping force to hold the small part. (The parts slides out of the collet when under load) Our competition holds a patent on a similar product and so we cannot thread the part into place. To make matters worse, whatever I design must retrofit existing product lines so my hands are really tied. Is anyone aware of a tried and true method of holding round parts securely using another round part?

 

[IFRs]

If you are holding if from rotataion, use a keyway?
If you are holding if from translation, use a set screw?
If might help if you could show a picture or web site...

 

[EnglishMuffin]

What's stopping you from increasing the gripping force on the "collet" ? Is there some sort of limitation ? Would some type of Ringfeder help ?

 

[jmillard]

I am trying to hold it from a linear force trying to slide the part out of the collet. I have an interferance fit between the parts to begin with, and if I increase the tension on the part, our assembly people will not be able to insert the decap pin into the spindle lock.

I can increase the pressure on the collet to allow it to have sufficient clamping force, but unfortunately, some of our customers don't do this causing the product not to work. We need to fool-proof the design so that it takes less force from the end user to make it work.

http://www.gunaccessories.com/hornady/Dies/index.asp

The die on the left shows a cross section of what I am talking about.

 

[Metalguy]

Having used many sets of your excellent dies (and fired thousands of your bullets), it seems to me that you can simply use a "blind" hole to stop the movement of the pin into the spindle. There isn't any force trying to pull the pin out, so just let the pin bottom-out in the hole. You can include several diff. length pins (they're cheap) to satisfy any reloader-I can't see why you need much adjustment in "stick-out" anyway.

 

[unclesyd]

You can try this site:

http://www.ame.com/spieth/csleeve3.stm

They handle the Spieth clamping components. I don't know if the they come in small sizes. I have had very good results using Spieth clamping system in the larger sizes. Cost and available sizes might get you, but I would contact AME. As mentioned above the Ringfedder lamp might work.

Have you looked a wire or ball detent type locking device as found on screwdriver bits.

 

[ccw]

Hi jmillard,
Hydraulic expansion chucks and arbors are used to precisely restrain cylindrical thin wall parts in some applications I am familiar with. I don't know if this would be feasible in your application. See

http://www.hydralock.com.

 

[jmillard]

Thanks for the help everyone, I think I have a new collet design that will work, I am prototyping it now, and should know how it works next week.

 

[EdDanzer]

Use a lock ring. In some hydraulic cylinders and cartridge valce both parts are grooved, the inside part has a hole drilled to hook the ring to, a slot in the outside part allows the ring to be fed into the groove by rotating the internal part.