Re: Consensus on recutting remington 700 threads
I know a lathe will do it, but thanks anyway for taking the time to point it out for me. I Did it that way for years, just like everyone else. Then I got better tools/machines.
The reason I prefer this way is more control over what is going on. If one wants to get in the mud with this (an engineering term, not a taunt) here's the deal.
The way a modern CNC encoder works the machine is verifying its position virtually every step of the way. 16 million little bits of location spread out over a 360* circle. In relative terms it means that the pitch is very linear, the roundness of the circle is very accurate, and the concentricity to whatever it was indicated from is very close.
Very close in practical terms means perfect. It's only going to get better by grinding the threads.
Work holding. I have a very rigid set up that isn't moving. I don't have to be concerned with four/eight little points of contact like a spider/cats head assembly has. I clamp this down and then move the whole table till I'm pointing straight at the Z axis.
Workholding is a fundemental principle in machining. It's 101 stuff. Anyone who's spent anytime in any kind of shop that produces good parts knows this. It starts with the floor that the machines are sitting on and extends all the way to the vise/chuck/fixture clamping the part. You can never have too rigid a set up. Your tools will last longer, your surface finishes will improve and the quality of your work will jump by leaps and bounds.
A multiflute carbide thread mill has very little chip load compared to the constant loading on a threading insert. This means very little tool deflection. Not saying a boring bar/internal threading tool isn't rigid, but it's not as rigid as a thread mill in a CNC milling center.
Last, I despise the initial thread being a razor blade. Irks me to no end. Unless I have a turning center with live tooling I can't alter the feature the way I can with the mill. Going from root to crest diameter over a .25 radius. What that translates to is a full thread form in a short distance. No more sliced fingers, no more potentially tearing the lead thread.
300_
Clocking position has nothing to do with how I start I pick up the existing thread. Your thinking about it too hard. I'm not going to tell you how to do it because I've seen enough of your posts to know that your a smart guy and creative enough to get outside the stupid box. Make the software do the work for you. . .
Last, I get everything I want done in one set up. Clean the face, clean the lugs, make the ID concentric with the bore CL, mill the threads, chamfer all the sharp edges and drill for a pinned lug. The set up is about ten minutes, the cycle time for everything is about 15 and that includes the thread milling portion.
Just a different tool to do the same job. I peel skin from cats going the other way, that's all I'm saying.
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