Neck Expanding to a New Caliber.

[hunter0528]

I was working on my exhaust system and though of why not create an expander ( same thread as your decapper rod to fit into you new caliber) that works the same way as the expander for an exhaust pipe. You would thread it into you sizer die and reduce the size of the expander, put you new case in, turn the rod sticking out of the top of the die and spread the case to fit into the sizing die. Then turn the rod to reduce the size and take the case out.

That way you are not trying to push the larger diameter expander, and possibly pushing the neck into the case. You are just expanding the case exactly to fit your sizing die.

Thoughts???

 

[Mikecr]

Can you make the parts?
I imagine it would be hard to find small enough collets for this.

 

[Dmagna]

I would be be worried about tearing brass. Mandrel dies work well

 

[hunter0528]

Can you make the parts?
I imagine it would be hard to find small enough collets for this.

I'm not a machinist no do I have a lath or milling machine. Just thinking as I was expanding the pipe on my exhaust with an expander.

 

[MagnumManiac]

This is why tapered expanders are made…just buy the die with the tapered expander then use a mandrel for the final size.

Cheers.

 

[Mike D Texas]

How would you control the expansion diameter?

 

[kopcicle]

It's actually a thing.
Insert
Expand
Retract
Repeat

Two methods

First is fixed adjustable just as you see in exhaust expansion tools.
Next is tension adjustable which will take a moment to explain.
Inserted the expansion mandrel is smaller.
When retracted it expands to an adjustable limit based on the tension of the original diameter.

There is a third method. A spring on a shaft is extended and or rotated to reduce its outside diameter and inserted into the case. Once tension and rotation are released the spring returns to it's original diameter less tension from the cartridge neck. This method works best on full soft annealed brass and may require repeated operations to get where you want to be. The advantage is, works best on full soft annealed brass and may require repeated operations to get where you want to be.

Good question

 

[hunter0528]

It's actually a thing.
Insert
Expand
Retract
Repeat

Two methods

First is fixed adjustable just as you see in exhaust expansion tools.
Next is tension adjustable which will take a moment to explain.
Inserted the expansion mandrel is smaller.
When retracted it expands to an adjustable limit based on the tension of the original diameter.

There is a third method. A spring on a shaft is extended and or rotated to reduce its outside diameter and inserted into the case. Once tension and rotation are released the spring returns to it's original diameter less tension from the cartridge neck. This method works best on full soft annealed brass and may require repeated operations to get where you want to be. The advantage is, works best on full soft annealed brass and may require repeated operations to get where you want to be.

Good question

Thanks for the information and Explanation of some of the other methods.

 

[Mikecr]

It's actually a thing.

Can you post a picture of it?

 

[scpaul]

Look up exaust pipe expander. They are made by all of the big tool companies and some of the junk companies too.

 

[Mikecr]

Look up exaust pipe expander. They are made by all of the big tool companies and some of the junk companies too.

There are 1/4" ID exhaust pipe expanders?

 

[VarmintBob]

expanding necks are why we have expander dies

 

[scpaul]

They don't make 1/4" expanders that I know of. I was trying to help you understand what and how it works. It's probably a long shot but you may try some plumbing and a/c tool companies. They probably have to joint some small tubing and may have something. The easiest thing would to use the expander. If it's too large chuck it in a drill or a drill press and use some wet dry cloth sandpaper (Crosan's Cloth?) to reduce a few thousands.

 

[lancetkenyon]

Expanding mandrels are so much easier and faster. Probably cheaper too.
I have them in:
.221 & .222
.241
.255
.261 & .262
.281 & .282
.305 & .306
.335

I can do 100pcs of brass in about 8-10 minutes.

I have necked up .243 to .257
.243 to .264 (stepped up with .255 & .262)
7mm to .308

Just a little lube on a Q-tip inside the neck if stepping up a caliber. 40° shoulders have to go slow however. 30° shoulders are no problem.