Changing Gears for Threading

D

ddickey

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I wan to turn a 20 TPI thread. I check the chart and get the gears ready to change and discover there is no way they fit. Has anybody heard of that before? Also in the pic what is the other chart? I see it has 20TPI in both. Just an alternate set up?

thumbnail_IMG_20161228_243033290[1].jpg
 
You will want to use the top chart for threading. The second one, with DP in the label, is mostly for gear work. Need more information and perhaps some pictures to help with the change gears issue.
 
They will fit. This is just a matter of getting used to the process of changing gears. Most likely you need to loosen the banjo bolts for the gears and move them to change their position. You loosen them just enough to allow them to slide, and loosen the entire banjo (forked arm thing that the gears mount to) just enough for it to rotate, then fit the new gear configuration on each bolt, then slide them around while moving the whole arm until they mesh, then tighten them down.

At least I assume that's the step that is missing?? Pics will help.

http://www.lathes.co.uk/latheparts/img40.jpg
 
I'm loosening the banjo. I'll go out and put on the proper gears. Then get a pic. Here I a pic of the gears.thumbnail_IMG_20161228_195301058[1].jpg thumbnail_IMG_20161228_195301058[1].jpg thumbnail_IMG_20161228_243051349[1].jpg
 
Well I'll be jiggered. I had no idea that gears D & B could move separately from gear E & C. Thanks for the help guys. pic of the final setup.

thumbnail_IMG_20170113_084608221[1].jpg
 
Glad to hear that helped. One more word of caution, just because I screwed this up (!) when I was first changing the gears on my lathe (less than a year ago): you don't need to tighten the gear bolts very much. They need to move freely so you don't end up shearing the bolt. It's not a standard bolt, but it is a good project on the lathe to make a new one... :)
 
Fortunately it's a 5/16-18, which I can cut with just the one gear. Or with a die, as I elected to do.
 
And another quick note, if they make a noise then check that you have left sufficient backlash between the teeth mesh.
I have to use three layers of standard copy paper between the teeth when setting them just to stop the horrendous whine they make if I dont.
 
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