O-Ring on expander mandrel?

[Sniper338]

I aint tried it, just gathered thoughts.

Expander Die:

Put a rubber O-Ring on the expander mandrel, then drop it in the expander die. Screw the cap down enough where the mandrel still has a tad of movement (like you would with a bushing in a bushing die). A round top on the mandrel, fit into a round bottom in the cap... allows mandrel to slightly move..

This allow the mandrel to free float a tad for a more straight alignment when pulling the case out of the expander die and off the mandrel?

seems like this would keep necks straighter

My idea for innovation/invention. Been brain storming it..

 

[chkunz]

This would be easy to test. The results would be interesting.

I did some testing once where I tried a lot of different things to see what contributed to runout and by how much. It was easy to get 50 to 100 data points and do the statistical analysis. This was in the days before folks had started using expander mandrels in place of the expander ball but the testing led me first to get rid of the expander ball and then ream the neck of the resizing tie. This got me to thinking about using the expander mandrel in place of the expander ball and that worked so well that I have been doing it ever since. Now this practice is common.

 

[Sniper338]

Could even skip the rubber O-Ring and make it a bushing sphereical inside, whith a sphere top on the mandrel and rounded bottom on the cap... allowing the mandrel to turn 360 degrees... This way it all free floats still, and all metal, titainium, and carbide type parts.

 

[Sniper338]

I wish I could manufacture this type protoype to test. I dont have to machines to do it!

 

[DirtySteve]

I believe the "6.5 Guys" use rubber o-rings under their sizing die and on the seating stem of their seating dies to cut down on run out. They have an article on their website about the testing. They used a progressive press I believe.

 

[Willie]

Just my thoughts......it would appear to be easier to make a die that is bored to fit & align the case body & neck to a fixed mandrel. Envision a die that somehow resizes and sets neck ID with a mandrel, in one pass.

 

[BenPerfected]

Just my thoughts......it would appear to be easier to make a die that is bored to fit & align the case body & neck to a fixed mandrel. Envision a die that somehow resizes and sets neck ID with a mandrel, in one pass.

Looks like a good design. Sinclair also has a tool that is pretty reasonable.
Ben

 

[Sniper338]

Looks like a good design. Sinclair also has a tool that is pretty reasonable.
Ben
View attachment 1033792

I got a 21st cent that matches the neck turner. Dont need an expander. Just over thinking it.

 

[spclark]

I leave my mandrel holder’s cap ever so slightly loose, mandrel can’t go anywhere but yet can still center up as it enters case mouth. Maybe not necessary but it seems to work.

 

[jsthntn247]

I leave my mandrel holder’s cap ever so slightly loose, mandrel can’t go anywhere but yet can still center up as it enters case mouth. Maybe not necessary but it seems to work.

yep

 

[Willie]

Looks like a good design. Sinclair also has a tool that is pretty reasonable.
Ben
View attachment 1033792

My comment was "tongue in cheek". I have not induced any significant run-out with my K&M holder or my Kenny Porter dies, using mandrels. It's nice to daydream about coming up with THE perfect solution for this or that need, but I leave that up to the more innovative among us.

 

[Fotheringill]

1. Not being a masochist, it was very painful looking at the hand made drawings.

2. It is an interesting thought and I will be following this thread.

3. Logically, a mandrel is the way to go instead of a ball or button There should be no resistance with a mandrel when the task is finished and you want to move the ram to release the case. It is a very good built in feature in the Lee Collet neck dies.

 

[dmoran]

@Sniper338
What expander die setup are you currently using?
How much is your expanding operation affecting runout/concentricity?

Myself use the K&M expander die (w/ riser) with an O-ring on the die, so the die is floating in the press. Then I use another O-ring on the expander securing screw, to allow it to also float.
Have not experienced any measurable lose concentrically at all with this setup.
Donovan

 

[Sniper338]

@Sniper338
What expander die setup are you currently using?
How much is your expanding operation affecting runout/concentricity?

Myself use the K&M expander die (w/ riser) with an O-ring on the die, so the die is floating in the press. Then I use another O-ring on the expander securing screw, to allow it to also float.
Have not experienced any measurable lose concentrically at all with this setup.
Donovan

I have a 21st century expander set up. I like it. Just over thinking things..

 

[dmoran]

@Sniper338
That's cool...... and all good !.!.!
If there was a "floating design" expander setup on the market, sure it would go over well.
I'm all for new idea's, designs, and concepts. Keep thinking !.!.!
Donovan

 

[1066]

I wish I could manufacture this type protoype to test. I dont have to machines to do it!

I've made just such a die - It worked very well. It has an "O" ring on the stem and under the retaining cap allowing a small amount of movement to self align.

Now, I'm no machinist or engineer, just a self taught hobby scratcher with an old lathe, so I'm sure some of you guys will wince at my efforts but here's a video of how I made it.