I need a sanity check on osing a DRO on a rotary table for gears.

tekfab said:
If you let me know what thread you want to cut and what TPI your leadscrew is i can do you a sketch showing how to set up the gears. It can seem daunting but i'm pretty sure if someone explains/shows you it'll all fall into place.
If i can help i will !

Mike Young
Click to expand...


OK. I think I understand how the chart works. Unfortunately I don't think it will work for this lathe.

You see, It's a clone of the Jet/Enco 1024. This lathe has an 8TPI leadscrew, but also uses a quick change gear box, and only three change gear positions. I bought this lathe used, without the optional metric change gears, therefore it only has the stock inch change gears in it. This consists of a 40 tooth drive gear, 70 tooth intermediate gear and a 40 tooth driven gear on the leadscrew gearbox. The intermediate gear I have is a single pattern, but the optional gearset for this position is actually a compound gear with a 120 and 127 tooth gears in it. I have attached a photo of the gear set/quadrant to illustrate better. Page 4, figure 2 shows B, C and D as "tumbler" gears. Those are the change gears.JET1024Manual42.jpg

Since I don't have ANY extra gears for this, I can not use the system you linked for me. My only choice appears to make the compound gear set.

JET1024Manual42.jpg
 
Well, never mind. I just invalidated the whole project.



I just checked the gear spacing and found that a 127 tooth gear with a DP of 16 measures out to 8.06 inches. I made a cardboard mockup, and it won't fit. Not even close. The quadrant is too small, with not enough adjustment/travel to get enough space between the gears, or even the hubs. I must have got some misinformation somewhere, as I was told a 127 tooth gear would fit in this machine. I should not have assumed that to be correct.

Now I have to re-figure the whole project, and come up with a combination that will work. :(

The good news is that I don't need the DRO anymore.
 
I use to buy brass and steel change gears from browning at a local bearing supply shop they had a catalog with a large range of change gears. Ray
 
FWIW -- You have done well so far. To clarify, you went thru all the math. You used all the suggestions. You made a dummy part from cardboard. You proved it will not work without wasting any time or material. R&D at its best. Congratulations are in order.

"Billy G"
 
Last edited by a moderator:
Your 3 speed gearbox is handy, it means that when you set up your gear train for a chosen tpi you'll have another 2 to select as well ! Gears can be got quite cheap and if you read that article HH tells you what gears you need to give you a comprehensive gear cutting range, just build up slowly starting with the ones you need for this project.

Mike
 
So I guess my priorities have changed on this.

I had been trying to do this with very limited information about this lathe, but I finally found the missing manual for it today. It describes the following optional change gears by tooth count: 25, 26, 43, 46, 47 and 60. Odd to say the least. I feel that I should point out that this unit does indeed have a full quick change gear box, with the typical A,B,C,D, /1,2,3,4,5,6,7 selector configuration. That means that while I don't have to change any gears for normal inch cutting, I have to jump through several gear combinations as well as use the quick gear selectors to cut metric threads with this thing. Certainly not like any modern lathe I have used. This leaves me to do the search for these gears with a DP of 16 and 20 degree PA. So far I have not come up with an affordable solution, but I will keep looking using others suggestions. I really don't feel like trying to cut all those gears right now. especially with a busy summer coming up.

I would like to thank all of you for your helpful suggestions. Even though this may have seemed like an exercise in futility, it served as a learning tool nonetheless. Now to find those gears.......
 
I second Bill's comment, you have done well. What thread pitch are you trying to cut ?

Mike Young
 
tekfab said:
I second Bill's comment, you have done well. What thread pitch are you trying to cut ?

Mike Young
Click to expand...


Thanks.

As many as possible. I am restoring this machine, so I want it to have the full capability it had when it left the factory. I have another lathe, but this one is smoother, more stable and more powerful. Originally I was planning to sell it, But I think I have talked myself into keeping this one, and selling the other one. The only thing stopping me is the ability to cut metric threads. I do a lot of fab work for RC cars, planes and helicopters. It's ALL metric, so I have no choice.
 
For all that desire it, I have an article from American Machinist 40 years or so ago that details all that needs to be done to cut metric threads on a lathe with inch lead screw; so far as I know, nobody sells stock gears with 127 teeth. I made mine by differential indexing, first as a pitch that fits my automatic gear cutter, then in the pitch that I needed for my lathe, which was coarser and of course larger in diameter than the dividing head would accomodate without blocking up for height. This being done, I am able to cut 127 tooth gears without having to index teeth, just start it and walk away, come back when it is done and no chance to make indexing errors, which is all too easy, especially with diferential indexing where the dividing plate moves while you turn the crank ---
 
You must log in or register to reply here.
Back
Top