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Neck turning: Trying to turn full neck but seeing cutting high on shoulder (280 AI)
- Thread starter 1Moose
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I turn almost all of my brass and your pic in post #1 looks fine you should turn into the shoulder just like you did in the pic. From now on turn your brand new brass before you load it. Just use your Expander mandrel to straighten up your brass and turn. once you fire your brass it will look really good. The cutter touching the shoulder is not a problem.
nksmfamjp
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That cutter looks like angles are wrong. Why is the neck part not parallel to the neck?
or did is it just locked in the tool crooked somehow?
Bob Wright
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It's called "cutter relief" so that you're not dragging the entire cutter length over the surface. Just a pin point at the leading edge of the cutter. It eliminates chatter, smearing....
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nksmfamjp
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Huh. I'll have to look at the K&M again. I don't remember that. But I never had this issue either.
Bob Wright
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My K&M is just like this. Matter of fact, all cutters including drill bits, end mills, inserts all have some appropriate amount of relief ground into them to reduce friction, poor finish and failure.
Bob Wright
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My K&M 35° cutter for 7RM for example is actually 38°. Therefore when using this cutter the only thing you'll be setting up for is the radius at the neck shoulder junction. If you're getting into the shoulder the cut would be a bit too deep. Just blend to the existing radius. Controlling the variation is your "trim to length" measured as over all length of brass. It needs to be consistent.
My AI cutter is 43°, cutting the same way by just blending to the radius.
Excuse my chicken scratches,
My AI cutter is 43°, cutting the same way by just blending to the radius.
Excuse my chicken scratches,
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nksmfamjp
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Yea, but see how the neck cutter is parallel to the neck on your K&M?My K&M 35° cutter for 7RM for example is actually 38°. Therefore when using this cutter the only thing you'll be setting up for is the radius at the neck shoulder junction. If you're getting into the shoulder the cut would be a bit too deep. Just blend to the existing radius. Controlling the variation is your "trim to length" measured as over all length of brass. It needs to be consistent.
My AI cutter is 43°, cutting the same way by just blending to the radius.
Excuse my chicken scratches,
I understand that K&M uses 3 deg of relief to ensure the neck is cut into the tip of the shoulder, but I'm talking about cutter alignment to the neck.
Bob Wright
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It's difficult to see but there is clearance behind the cutter radius. I just slipped in a .0025 shim stock at the very back of the cutter.
Mike Matteson
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The one thing for sure is you have to cut the COAL to the exact length to set to cut thickness of your necks. Otherwise you will never get it right. OR, You'll have to set each time to cut the necks or risk cutting to long or to short. The other is new brass, the ID will vary some from case to case. So my thinking is you need to expand the ID of the neck to fit the cutting mandrel you are using. You spring back involved in this too. I find it interesting and somewhat complex to overcome the problems in this set up. The other is I will have to see what disagreement come from this I stated here. So I don't have the equipment to cut the mandrels to thickness, so off to the Smith twice now. I have a 21st Ctry neck cutting, and a Gen 3 case length cutter systems, I feel I can achieve both. Starting age 14 to reload, I fell in love with it. It's been a learning in progress from then on.
1Moose
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Thanks Mike, in my "pre-reading" before starting on the neck-turning adventure I also saw that the relative sizing between expanding mandrel and turning mandrel was critical, so I got both of them when I ordered the Sinclair 4000 turning kit. The fit on the turning mandrel wasn't as tight as I thought it might be based on reading people describe that it should be "tight," but the expander mandrel does measure only .001 larger than my turning mandrel. The case spins freely for me, but I thought it might be more snug. I get the tiniest amount of play in the case when it's on the turning mandrel. Perhaps it'd be even tighter if I annealed the cases before expanding them (I just got an Annealeez annealer and have yet to set that up to use).
I get this same minimal movement on new brass that I expanded with the expander mandrel, and I'd think that brand new brass wouldn't need to get annealed before expanding, but I'm just learning all this from scratch. I'm going to look to see if more precise case trimmers are in my price range given all my current expenses.
