Button cutter making chart or advice

[Suzuki4evr]

Hi guys.

I have posted about a thread dial indicator I want to make for my Mashstroy 1.5m lathe,but I don't want to post this part there.

I can't really afford module involute gear cutters so I need to make a single tooth cutter to do the job. I know there is a chart for making button cutters that show the size of the cutter and depth of cut. Can someone help me or point me in the right direction or give some advise on rhis. Just keep in mind that this is for making a module cutter but a DP chart or info is also welcome.

I have not figured out wich module cutter I need,but I will try to get to that tonight. Any advice would be appreciated.

Thank you
Michael.

 

[derf]

http://www.david.rysdam.org/

 

[Bob Korves]

A threading dial indicator fits the Acme threaded lead screw, not an involute thread. Simply grind a fly cutter bit until it fits the lead screw threads and use it to cut the teeth. The fit need not be at all perfect, all you are doing with it is turning the threading dial. The bigger issue is in making the angle of the teeth match the angle of the lead screw threads(if the threading dial only fits the lathe in a vertical position, not able to be tipped side to side.) Again, does not need to be perfect, there is essentially no load from a threading dial, well, should not be any load. Again, a perfect fit is not necessary. In use, engage the threading dial teeth into the lead screw until they stop, and tighten it in that position. Keep the threading dial and the lead screw lubricated and it will probably last forever.

 

[P. Waller]

A threading dial indicator fits the Acme threaded lead screw.

I have never used a lathe that was manufactured with an acme threaded lead screw, every machine that I have ever used has either a square thread or a ballscrew, this does not mean that they do not exist just that I have never used one in 30 years in the business.

One may employ any number of different methods of positioning a dial along a screw thread, an involute gear of the correct pitch will work fine for this. A thread dial is not a load bearing element of the machine merely a position indicator, it should be easily rotated by your fingers, this does not load the screw or the gear.

 

[Bob Korves]

I have never used a lathe that was manufactured with an acme threaded lead screw, every machine that I have ever used has either a square thread or a ballscrew, this does not mean that they do not exist just that I have never used one in 30 years in the business.

One may employ any number of different methods of positioning a dial along a screw thread, an involute gear of the correct pitch will work fine for this. A thread dial is not a load bearing element of the machine merely a position indicator, it should be easily rotated by your fingers, this does not load the screw or the gear.

With regard to true square threads, you are correct with some lathes, mostly older ones. A true square thread is seen on many older and larger and nicer lathes, though I have seen others, including "V" threads on some inexpensive smaller lathes. My own Asian 13x40 made in 2006 has a lead screw with visibly tapered flanks of the lead screw threads, "looks" like Acme, and it is in like new condition. True square threads are more difficult and expensive to make, so modified square threads and other shapes are often used. As long as it matches the half nuts, all is well.

My point was that purchasing an involute cutter would be a waste of money, though it would probably work fine if it had a suitable diametral pitch to fit the lead screw threads without bottoming in the threads before contacting the flanks, or the crest of the tooth being too wide to enter the lead screw threads. Still, it would be a two point contact, which is fine for a threading dial, which should normally have very little rotational loading or significant wear. A form ground flycutter bit, hand and eyeball ground to match the lead screw thread form, but not bottoming in the thread, and tested for fit regularly while grinding it, would be simple, cheap, and would work fine (better?) for making a gear to match the lead screw more than adequately.

 

[P. Waller]

With regard to true square threads, you are correct with some lathes, mostly older ones. A true square thread is seen on many older and larger and nicer lathes, though I have seen others, including "V" threads on some inexpensive smaller lathes. My own Asian 13x40 made in 2006 has a lead screw with visibly tapered flanks of the lead screw threads, "looks" like Acme, and it is in like new condition. True square threads are more difficult and expensive to make, so modified square threads and other shapes are often used. As long as it matches the half nuts, all is well.

My point was that purchasing an involute cutter would be a waste of money, though it would probably work fine if it had a suitable diametral pitch to fit the lead screw threads without bottoming in the threads before contacting the flanks, or the crest of the tooth being too wide to enter the lead screw threads. Still, it would be a two point contact, which is fine for a threading dial, which should normally have very little rotational loading or significant wear. A form ground flycutter bit, hand and eyeball ground to match the lead screw thread form, but not bottoming in the thread, and tested for fit regularly while grinding it, would be simple, cheap, and would work fine (better?) for making a gear to match the lead screw more than adequately.

We agree then.
Any device capable of following the position of the carriage in relationship to the lead screw will work as a thread indicator. The only limiting factor is the space required for a straight involute spur gear of large PD and small tooth count, it may be difficult to incorporate such a thing into an existing machine.

 

[derf]

I used a slitting saw and a thread mill to cut the teeth close enough.

The dial was tipped to match the helix of the leadscrew.