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Will a press self centre?
This is an old Lyman turret press. The press indexes cleanly and locates firmly, but the ram has a slight axial movement about it's centreline at the top of it's stroke - I estimate about 30 thou. Clearly wear in the casting is the major cause.

Now will the ram self-centre on the die assuming the centre of the ram movement encloses the centre of the die?

It may well be the die will create the easiest path for the ram.

Would this work with ALL types of cases?

I have one with the same problem ,it cants and distorts the case.I cured mine by stripping it and boring out the worn area of casting then pressing in a bronze bush the exact size of the ram. simples.

clapclap

I'd test the rounds it makes and see if the run out is a problem.

Thanks,
I assume run out is some measure of eccentricity?
I've not encountered the term before.
V blocks and dial gauge?

++Just looked it up
'Runout is specified on cylindrical parts. It is
measured by placing a gauge on the part, and
rotating the part through 360 degrees. The
total variation is recorded as the runout.'

Any ideas on typical numbers ?
Thanks.

You can certainly test case neck and bullet run out with V blocks and a dial gauge and magnetic base. Just place the sized case in the v block and rotate it slowly picking up off the neck, it should be better than .001" and with a seated bullet under .0035" is going to be a good start given the method of measuring.

ovenpaa wrote:You can certainly test case neck and bullet run out with V blocks and a dial gauge and magnetic base. Just place the sized case in the v block and rotate it slowly picking up off the neck, it should be better than .001" and with a seated bullet under .0035" is going to be a good start given the method of measuring.

Thanks - and I thought my metrology lab classes were a waste, 46 years ago!
I wonder what a quick check with calipers would give - it would show if there was a major problem.
I suspect I'll get away with it for 357 carbine rounds, but let's get the gear and check. 223 is altogether another matter perhaps.

I'd need a lot of confidence in a machinist getting the same centre in a re-bore job although the fix is engineeringly excellent - is that a real word?
A few thou off centre and we could have the same problem with a different cause. I wonder what the tolerance on a new press is.

Interesting link for anyone interested http://blog.sinclairintl.com/2010/06/25 ... t-run-out/ :goodjob: