Ok, maybe I'm really missing something here. With a V-thread, there is a tiny bit of flat at the root, but for the most part one v-thread tool can cut a range of thread pitches by cheating on the depth in favour of hitting the pitch diameter. It was my understanding that trapezoidal threads are not so forgiving, and the single point tool form had to be pretty much bang on.
Are you saying I can just get a 30° tool, and go a little deeper so long as I hit the correct pitch diameter?
Help identifying and duplicating this thread.
- Bill Shields
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Re: Help identifying and duplicating this thread.
I have always done acme threads groove up the middle first then front flank then back flank with a tool that is less then a thread form wide.
But then I have been known to do things the hard way..
But then I have been known to do things the hard way..
Too many things going on to bother listing them.
Re: Help identifying and duplicating this thread.
Ok, my first thought was "that would simplify the grinding process". My second was "Wait, what?"Bill Shields wrote: ↑Thu Mar 24, 2022 9:38 pm I have always done acme threads groove up the middle first then front flank then back flank with a tool that is less then a thread form wide.
How does that work? Do you have the compound set parallel to the ways instead of at 14.5°, using the carriage to control depth and the compound to shift left and right? If you are creeping up on the final dimension, how do you know if you need more depth or more width?
I'm so confused now...
Re: Help identifying and duplicating this thread.
Two separate go/no-go gauges, one with narrow threads and varying diameters, the other with varying thread widths?
Re: Help identifying and duplicating this thread.
Cutting the three features independently isn't a bad idea, assuming one can measure the major diameter, which can be used as a guide.
One thing to be careful of. When one single points threads, the tool should be advanced towards the side of the cut that is loaded by the screw. In a right hand thread, the trailing cut isn't so loaded. Drag on the carriage will ensure that you don't get a drunken thread. If the carriage has a lock, it can be set with enough friction to prevent floating--or the hand wheel can be gently restrained while the cut is taken. Don't trust to luck.
H
One thing to be careful of. When one single points threads, the tool should be advanced towards the side of the cut that is loaded by the screw. In a right hand thread, the trailing cut isn't so loaded. Drag on the carriage will ensure that you don't get a drunken thread. If the carriage has a lock, it can be set with enough friction to prevent floating--or the hand wheel can be gently restrained while the cut is taken. Don't trust to luck.
H
Wise people talk because they have something to say. Fools talk because they have to say something.
Re: Help identifying and duplicating this thread.
Makes sense. But then, most of the advice you give does.
- Bill Shields
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- Joined: Fri Dec 21, 2007 4:57 am
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Re: Help identifying and duplicating this thread.
Groove up the center.
Compound set parallel to screw axis.
Feed in X cutting on front flank
When at depth on front flank, retract to starting od and move cross slide BACK to new starting position and repeat.
Compound set parallel to screw axis.
Feed in X cutting on front flank
When at depth on front flank, retract to starting od and move cross slide BACK to new starting position and repeat.
Too many things going on to bother listing them.
Re: Help identifying and duplicating this thread.
As for the thread profile, A cutter without sharp corners will go farther between sharpenings. A grinding wheel even more so, assuming the threads were ground.
It's a dirty trick to leave you with maybe about 1/2 the effective thrust surface of an acme thread. The angle of the flanks make it even worse. I can see why the nut wore so badly.
It's a dirty trick to leave you with maybe about 1/2 the effective thrust surface of an acme thread. The angle of the flanks make it even worse. I can see why the nut wore so badly.
BC
If there was only one way to do each machining job, the smell of sulphurized cutting oil smoke would have fewer fond memories.
If there was only one way to do each machining job, the smell of sulphurized cutting oil smoke would have fewer fond memories.