flat base flange chamfer

[405]

I have an R Corbin swaging set up. The bullets I use are flat based, tapered, pure lead for paper patching. The final step where the core slug is taper swaged into final form always leaves a small, irregular knife edged flange around the bullet base. Yes, the base punch to die fit is excellent. But the high pressure final swage of the pure lead still leaves that tiny, nuisance flange around the base. For paper patching that is a real PITB! Have been using a simple Lee chamfering tool to remove it but even that is not the best. Seems to roll the sprue edge about as much as it trims the small, thin edge. Anyone else run into this and if so any slick ways or tools to lightly and cleanly chamfer that flange from around the bullet's base???

[Bullshop]

When I have that problem it is usually tracable to one of two things,
a worn punch or
too much pressure.
The worn punch can often be cured by squaring up the tip in some way. The slightest little bevel at the tip will cause problems. True it and square it.
If too much pressure I back out the die ever so slightly until the flo by stops.
If these are not the causes of your problem I know not what. One of the two or both have always been the source of trouble for me.
BIC/BS

[405]

Bullshop,

I was afraid someone would suggest that. No way I can do the re-facing myself- don't trust my vertical lathe combined with a hand held grinder

Yes, there is a very small chamfering of the edge of the base punch- probably to prevent chipping of a perfectly flat and sharp edge.

I don't think it is too much pressure- just using enough to where the lead completely fills the nose cavity and just starts to enter the punch out rod hole in the nose.

Re-facing is a last resort but may have to if I get tired enough of hand trimming the base of the bullets. Will have to bribe a buddy up the road who has a lathe. Even with a lathe, need to rig a small grinder to do the facing of the hardened punch.... similar to another thread elsewhere on this forum or over on reloaders

[Buckshot]

..............405, If it's just a VERY fine film of lead that is bypassing the punch, and you're using consistant pressure and dwell time for the final swage, trimming the excess lead really shouldn't be an issue with weight consistancy. And this must be the case sisn'e you're noting mentioning anything about it. Simply use a single edge razor blade to cut straight across the boolit's base to cut the tags off.

A possible fix if the punch isn't tapered is to have it chrome plated. However you'd have to know what the clearance is and then talk to the plater about what the chrome will add to it's OD. Also, if your buddy with the lathe has a tool post grinder, or better yet a surface grinder you could get it plated and then ground to the right OD.

...............Buckshot

[crossfireoops]

I've studied this swadging a bit, .....and have exactly zero experience in the practical sense.

For the application discussed, ....what would be the optimum tolerance between the punch and die?

Thanks for your patience.

GTC

[Red River Rick]

crossfireoops:

0.0002" - 0.0003", per side would be optimum clearance between the punch and die. Anything more could or will result in flashing (depending on swaging pressure) around the base and or the nose.

RRR

[crossfireoops]

So, .....for a .4580" die, .....a .4494 / .4496" punch ?

Like that?

GTC

[Red River Rick]

No, not quite. Ideal size would be 0.4577" - 0.4576" and the smallest would be 0.4574" for the punch to correctly fit the die.


RRR

[crossfireoops]

No, not quite. Ideal size would be 0.4577" - 0.4576" and the smallest would be 0.4574" for the punch to correctly fit the die.


RRR

OOps !

GTC

[crossfireoops]

How is it that on the cranks, ....with a notepad and calculator on the bench, one does so well, and anywhere's near a keyboard reverts to 2nd grade or below math.

I better avoid CNC programming, I reckon

GTC

[Red River Rick]

No magic tricks here, and no CNC programing.

If you swing your compound rest to 5.8 degrees off of the centerline of your machine, and using the compound rest for your infeed rather than the cross-slide handwheel. For every 0.001" of feed on the compound rest handwheel, you will achive 0.0001" of infeed. Basically a 10:1 reduction.

I use ceramic inserts when I machine my punches after heat-treating. This will also work well for those who want to do some internal grinding using their Dremel or Air grinder.

I hope that this bit of info will help.


RRR

[crossfireoops]

Exactly why I'm asking all these dumb questions.....

This is a neat site!

Whole new ball game, ....ceramics.

Guess the buzz-word is hard turning,.......

Wish the paint on my machine was that slick,......it runs pretty true, nonetheless.

Again, great site,.....be ready for a compendium of questions.

GTC