5C collet question

[GRUMPA]

I'm trying to find an answer on how small a person can machine a 5C expanding collet. Every time I use my Google-Foo I get tons of places selling them but no real answer as to how small a person can machine it too.

What I need is an expanding collet that can be machined down to .200 and still be functional.

Don't really know if it can be done but I don't want to be buying something only to find out it wont work, then what am I going to do with it kinda thing.

Having worked in a machine shop all my life you would think I would remember that, but I was a precision grinder by trade and not a machinist, so my machines were a lot different.

[elk hunter]

A little more information please, possibly a description of your project/problem. I'm not picturing what it is you want to do. There are machinable collets and they are fairly cheap.

[M-Tecs]

For expanding collects I have never taken one down that small but they do make them. http://www.roviproducts.com/Minicolletpage.htm

Royal lists 1/4" as the smallest http://www.royalproducts.com/content/files/products/00%2039.pdf

[country gent]

The slits are around .090 wide so going to .200 isnt going to leave alot of "finger" area to hold and support. Depending on what your trying to do a fitted solid pilot turned true to the spindle and part held tensioned with a live center may work better. Fopr a one off a turned pilot pressed into may do just what you want. A piece of cold rolled steel just under od of part with stub turned size for size and close to length of .200 hole and a live center point cup or extended point ( if part is thinwalledthen getting to solid material is a plus) will support and allow part to be machined. For very light machining the turned stub with double faced tape or super glue works also. We did alot of thin fragile parts in both mill and lathe like this on tape or glue. The draw back to glue is every couple parts you need to clean the build up from the fixture. Tape needs to be replaced each part. If its a thru hole of .200 you can use a turned mandrel between centers. turn mander slightly longer than part .200+ on back end -.200 on front end push into hole snug and set between centers. Knowing what your wanting to do would make helping with info much easier

[GRUMPA]

Here's what I'm doing currently.

http://castboolits.gunloads.com/attachment.php?attachmentid=137675&d=1429817968

http://castboolits.gunloads.com/attachment.php?attachmentid=137676&d=1429818072

But I've changed things a bit to the pictures. Now I made a single center rod that fits all the way in the case and bottoms out at the I.D. base of the web. Then I just use a live center and do my machining on the head, but there seems to be a problem. Live centers come in all types, cheap...and not so cheap.

The bearings in those things seem to go out rather rapidly with what I call "Friction Driving" because I put a lot of force on it to hold the part and machine the head. Those pictures are just for the 35Rem cases I do, when I do the 25, 30, 32Rem cases there's a lot of material coming off the head.

I was thinking of just using an expanding collet to hold onto the case via the primer pocket and use a live center with lite pressure and do the machining.

[Ole Joe Clarke]

Why don't you bore out a collet and turn hulls around and clamp them on the OD? I would think the cartridge brass is stringy, not like free machining yellow brass.

[smokeywolf]

Grumpa, it sounds like you're describing an expanding mandrel as opposed to a collet. Even if you could machine an expanding mandrel small enough to fit in and expand in the primer pocket, the force needed to keep the case from spinning when you do your machining to the O.D. would likely stretch out and enlarge the dia. of the primer pocket.

If I were looking at doing several hundred or more cases, I'd take a piece of 3/4 to 1" dia. grey PVC round stock and bore a pocket in it that matches as closely as possible the shape and size of the cartridge case that you want to work on. The I.D. of your pocket in the PVC should resemble the chamber of the firearm in which that case is used. You will of course leave the pocket shallow enough that the case head sticks out.
The case should slide into the mock chamber that you've machined in the PVC with very slight resistance.
Once you put the case in your PVC "mock chamber", you put the that PVC with the case in it, into a 5C collet that fits the O.D. of your PVC bushing and when clamped in the collet the PVC bushing will collapse just enough to captivate or clamp your case and allow machining of the case head.

I use a very slight variation of this method to hold onto 45-70 cases so I can trim them down to 45-60 length.

[MarkP]

Several years ago I would purchase collets and custom strippers from a company in MN; just looked and they are still in business. John Schuh should be able to help or point you in the right direction.



Name: MASTER-MATIC, INC
Located at: 8657 JEFFERSON HWY , Osseo, Minnesota, United States
Phone: 7634254929

[country gent]

A soft collet could be bored to body taper and a collet stop used to set length of of case mouth or a special end turned to set of off shoulder. Light clamp pressure should hold well and allow machining to be done. artridge brass does machine pretty easily leaving a nise finish normally. Maybe the turned mandrel with a hard rubber washer between face and case head. less pressure for center to maintain to provide grip. An expanding collet may deform primer pockets with the needed force and low bearing area. You might even try a wilson trimmers case holder for a body collet. use a soft rod to knock them out slide in with a light tap of a small bumper or mallet to set. A rod to reach thru the spindle with a couple nylon washer to locate Shaft on case mouth with a nylon or derilin end and about 6-8" longer than spindle would allow the light tap needed with out removing trimmer bushing

[scb]

FWIW if I were doing this I'd turn a pin that was a tight fit to the ID of the neck then just clamp on the neck with a 5c. With the pin in place I wouldn't think it would hurt the case any. Actually I'd just use a gage pin to go inside the neck.

[GRUMPA]

The thing about holding onto the body itself is consistency. So I hold onto the body with a collet stop on the mouth of case, now I need to have another operation just to trim them all the same, not gonna happen.

Sure someone can use a collet stop, which I do.....but it isn't accurate enough. The way I do it now it's accurate withing .001 and I do hundreds at a time and they all need to be the same. That spud you see does have a collet stop to prevent it from traveling when I apply pressure to hold the part with the live center, works great but like I mentioned the bearings are the things that go out.

Call it what you will but when I look for and expanding collet it shows me what I think I need.

It's set up to accurately hold head dimensions, solid stop, holds the same head dimensions all day within .001.

[M-Tecs]

For what you are doing I would use an emergency collet. http://www.amazon.com/Hardinge-5C-E-4-Slot-Emergency-Collet/dp/B007FVW2HG


Just install the pin and bore it to the rim size. Once bored you remove the pins and use it as a standard collet. The rim will give you adequate holding force.

[country gent]

A stop pin for the collet stop bored .010-.015 over nech dia and shoulder angle on face would set length of of the shoulder instead of the case mouth. It might help with consistancy some there. Most collet stops use a simple thread and lock nut a head on it like mentioned above might have more surface and better alighnment. On some parts that were held from a shoulder we had stops made up like above mentioned with a clearence hole and face to locate from shoulder or angle. You could locate parts very closely like this.

[chuckbuster]

Grumpy
I have a couple ideas for you, let me look at things when I get to the office in the morning and I will PM you.

(I sell this stuff for a living)
Kevin

[GRUMPA]

I went through some sites looking at better live centers, man.....they just don't'give them away. But you would think for $70 plus shipping those suckers aught to run the machine as well..

[country gent]

Grumpa I had a royal live center #3 morse taper extended nose with load bearing of 300lbs and constant thrust force bearing ( when part expnded it maintained the center points pressure ) at work it was several hundred dollars. Good live centers are expensive and much more involved than the old bearing and point caps of the cheap ones. Running brass case in production at any kind of speed is going to be hard on a live center. Keeping them lubed properly and clean is a big thing.

[dh2]

I don't look hard to me
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=619-3391&PMPXNO=16721112

[M-Tecs]

I don't look hard to me
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=619-3391&PMPXNO=16721112

Never noticed nylon ones before. Only used the steel ones.

[chuckbuster]

HARDINGE #100 Sure Grip 5C Expanding Collet, 1/8" min-1/2" max dia

Collet is "Soft" machined to size by end user.
Kevin

[akajun]

I would chuck a piece of scrap in a 3 jaw, then bore and tap to 7/8 x14, then mark one of the jaws and the scrap with a sharpie. THen take a sizing die, remove the decaping rod, and stick whatever case you are working on in it with a dead blow or rawhide mallet. INsert the die into the scrap, put it back in the three jaw using your sharpie mark, and turn off whatever you need at the base/rim, then drive it back out with a punch.

[M-Tecs]

The OP is looking for a solution that is workable to do hundreds at a time for resale. It has to be very quick plus accurate to be workable.

[fg-machine]

i dont see a lot wrong with how you are set up to do it already . i do understand the frustration with the cost of a good quality live center .
but i think you might find it more useful to spend the $200-300 it will take for a good quality live center then to put the same money in getting set up for the expanding collet .

you might be able to slightly reduce the pressure it takes to drive the case by switching to a hss insert instead of the carbide

[IllinoisCoyoteHunter]

I am familiar with the 5c collet system, but not quite sure how the "stop" work. Is there a way that the "stop" can be modified to have a pilot made and screwed on the end to fit snuggly inside the case neck...and then the collet can be clamped on the OD of the case body? Basically the stop both aligns the case concentrically and also allows it to stop at the same spot each time. The pilot will also help support the case because with tapered cases you wont have much surface area gripping the case when clamped in the collet (enough, though to turn the rim down). Just throwing out some thoughts...

[GRUMPA]

I am familiar with the 5c collet system, but not quite sure how the "stop" work. Is there a way that the "stop" can be modified to have a pilot made and screwed on the end to fit snuggly inside the case neck...and then the collet can be clamped on the OD of the case body? Basically the stop both aligns the case concentrically and also allows it to stop at the same spot each time. The pilot will also help support the case because with tapered cases you wont have much surface area gripping the case when clamped in the collet (enough, though to turn the rim down). Just throwing out some thoughts...


Tony, trust me once you've used a collet stop it's 1 of those things you almost can't live without. I have on order a $150 live center but unlike my other ElCheapo centers this has a beefy thrust bearing set up. When I do the 25, 30, 32Rem as well as a few others, the head dimensions and all the head diameters are completely changed. So a solid locating point like in my pictures that shows the head locating against the spud is a must. With that set up, once the stops are set, goes real fast, like a minute if that. The hardest part of those Rem cases is the Hydroforming, that's what takes the most time..

[IllinoisCoyoteHunter]

So you cant modify the stop so the case mouth fits on and comes to a hard stop on a pilot? Sorry for my ignorance on the 5c stops. I made one for my ER40 that would work great for an op like this.

[smokeywolf]

IllinoisCoyoteHunter, you can make a 5C stop screw act as a hard stop for the inside of the case head, but because of the low coefficient of friction between the 5C collet and the brass, you'd have to grip the case so hard that there would be a good chance of squeezing down the dia. of the case.

This is why I suggested holding onto the case with a PVC bushing. PVC provides a much better grip than a brass emergency collet.