I think that the issue here has a couple of sources. There has so much repetition of the idea that cases have to have a wring on fit on the turning mandrel, that it has become an accepted, unexamined "truth". Knowing this ,tool manufacturers make their expander mandrels to produce that result. It is that fit that produces the heat. Loosen the fit slightly and the heat is not an issue. This can make technique a bit of an issue, but that is not rocket science. Flame away. I have put on my nomex underwear ;-)
How to create a heat sink to keep neck turning tools cool and precise
- Thread starter Cassidy
- Start date
@P1ZombieKiller
That’s really good’ personally I can start distinguishing one bushing size past 300 yards. I test a lot of stuff but 1/10,000 in neck wall due to heat isn’t one of them.
That’s really good’ personally I can start distinguishing one bushing size past 300 yards. I test a lot of stuff but 1/10,000 in neck wall due to heat isn’t one of them.
P1ZombieKiller
Silver $$ Contributor
And shouldn't be.
Yep, that’s what we’re going for, not to be able to see the difference at 100 yds, so it’s working.
D Coots
Silver $$ Contributor
For me using a Pumpkin I found if I started out at room temp my measurements changed until it warmed up, then leveled out. Now I run hot water in it for awhile and go to it....I use ATF for lube, a dab with a q tip. NOT A BATH. Most gets shoved off when pushing case on the mandrel anyhow. No sense in having excess going in case making a mess. Less is good.
Later
Dave
Later
Dave
jackieschmidt
Gold $$ Contributor
When I single point turn cases in my lathe, I have a mist cooler blowing on the mandrel.
I am turning a neck about every 25 seconds, the heat of the cut will transfer to the mandrel in the chuck to the extent where I can measure it if I don’t.
I am turning a neck about every 25 seconds, the heat of the cut will transfer to the mandrel in the chuck to the extent where I can measure it if I don’t.
Correction: a micrometer is accurate to 0.0001" if calibrated and properly used at room temperature. With clean anvils (no carbon layer). Any machinist will tell you everyone measures a little different.
Guys are not mentioning that after firing and sizing the neck thickness changes along it's length. Maybe you should turn afer each firing. I think this is all OCD. Somewhere on this website it was stated that firing causes the brass to flow forward with each shot. changing the neck thickness.
Several years ago I took a case that was turned and fired at least 3 times. I ran my turner over the neck and couldn't believe how much brass was removed.
At work we were not allowed to use a micrometer unless it was professionally calibrated once a year and had the cert sticker attached.
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butchlambert
Site $$ Sponsor
Why?
jelenko
Gold $$ Contributor
I do too. But, then, if you're chasing 1/1000 of an MOA............
Circling back to the use of the clutch function on the ball mic and just going off recall , when I just use feel I cut right at .0108, but if I increase tension until the clutch clicks I feel much more resistance when inserting the case into the mic and get a reading of .0106 ish.
Open question to the thread readers.
Which is correct ?
Open question to the thread readers.
Which is correct ?
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P1ZombieKiller
Silver $$ Contributor
I am not machinist by any means, but i just feel that if there is something that "stops" at xxxxx amount of pressure, it should stop at that same amount of pressure most of the time.
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I just measured the neck thickness on some .308 Lapua cases of mine that has been fired 15 times now and they measure .0141". I originally turned them to .014" after the 1st firing (though I'll admit I don't think I initially paid much attention at the time if they were exactly .014 or .0141). If they're growing after each cycle of firing and sizing, it must be a very very small amount, if detectable at all. ¯\_(ツ)_/¯
Certainly, some amount of donuts develop and that would results in some brass removal if I were to turn them again. But since I seat my bullets where the bearing surface is well above any donuts, I don't see any benefit in turning the neck more than the one time.
As I think about it, those donuts can act much like bushing dies that don't size all the way down to the neck-shoulder junction, which some reloaders tout as benefiting the centering of the cartridge when chambering.
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butchlambert
Site $$ Sponsor
Fellers! This .0001" on your necks? It would be much more productive to do a lot of quality practice and absorb what your windflags are telling you.
Mostly I ID reamed when I was forming and worried about leaving a thick neck with a donut at the neck/shoulder junction.
I'd prefer to ID ream also so as not to leave a possible ridge so to speak that knowing my luck I would end up with if I OD turned.
butchlambert
Site $$ Sponsor
Since I started fire forming without a bullet I have no donuts. Reaming will not true the concentricity of the OD to the ID.
When I turned my cases a 2nd. time the brass removal was everywhere. Not just the donut area. I'll turn a case that was already turned and see if I can put up a pix. I suggest that all of you run your turner a second time and see what happens instead of all of the quesswork replies.I just measured the neck thickness on some .308 Lapua cases of mine that has been fired 15 times now and they measure .0141". I originally turned them to .014" after the 1st firing (though I'll admit I don't think I initially paid much attention at the time if they were exactly .014 or .0141). If they're growing after each cycle of firing and sizing, it must be a very very small amount, if detectable at all. ¯\_(ツ)_/¯
Certainly, some amount of donuts develop and that would results in some brass removal if I were to turn them again. But since I seat my bullets where the bearing surface is well above any donuts, I don't see any benefit in turning the neck more than the one time.
P1ZombieKiller
Silver $$ Contributor
If you tumbled in pins after initial turning you will probably see brass removed near the mouth on subsequent turnings.
I turned a batch of brass to .013 and tumbled them in pins to clean lube for 10 minutes only. Lube didn't all come off so I added more Dawn and tumbled them again for another 10 minutes but forgot them and they tumbled for about 30 minutes.
I knew I'd have to re-chamfer the mouths. I checked the necks after chamfering and found the neck mouths to now be about .0135 +/-. I measure everything 10th piece as I'm turning so I know the entire batch was .013+/- after first turn.
I re-turned the entire batch. Brass was removed during this 2nd turning for .025 - .050 up the neck from the mouth!
I had thought chamfering would remove peening from pin tumbling before this episode.
Learned not to tumble in pins to remove turning lube....no matter how long.
I turned a batch of brass to .013 and tumbled them in pins to clean lube for 10 minutes only. Lube didn't all come off so I added more Dawn and tumbled them again for another 10 minutes but forgot them and they tumbled for about 30 minutes.
I knew I'd have to re-chamfer the mouths. I checked the necks after chamfering and found the neck mouths to now be about .0135 +/-. I measure everything 10th piece as I'm turning so I know the entire batch was .013+/- after first turn.
I re-turned the entire batch. Brass was removed during this 2nd turning for .025 - .050 up the neck from the mouth!
I had thought chamfering would remove peening from pin tumbling before this episode.
Learned not to tumble in pins to remove turning lube....no matter how long.
Correct. new> turned> fired several times> turned. You will be collecting real info instead of this is what I think is happening.
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