-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Bad day of threading
- Thread starter Shepherd
- Start date
T
Tom Griffin
Forum Guest
Register Today
Not sure why you are looking at gearing. Initially you said that the first cut lined up perfectly with the thread gauge, which would indicate that the gearing is correct. 
If your tool refused to cut to depth, the problem would seem to lie there, not with the gearing. Even if the gearing was not correct, you should still be able to cut a thread of questionable pitch.
Tom
If your tool refused to cut to depth, the problem would seem to lie there, not with the gearing. Even if the gearing was not correct, you should still be able to cut a thread of questionable pitch.Tom
It is more that each pass seems to run into/over each other slightly, like the tool isn't tracking with the first scratch cut....Not sure why you are looking at gearing. Initially you said that the first cut lined up perfectly with the thread gauge, which would indicate that the gearing is correct.
Tom
but I don't disagree with you...that's what has me banging my head, I can't figure out if its me or the machine!
T
Tom Griffin
Forum Guest
Register Today
Make sure the shear pin in the lead screw is not sheared. If it is, the lead screw could be slipping, causing your thread to wander.
Tom
Tom
4
4GSR
Forum Guest
Register Today
Sheperd,
You can't get there with 72 tooth and 33 tooth gear. To get it to work out, you need a 18 tooth and 33 tooth gear. The middle gear does nothing for you, its there for the ride. It can be any number of teeth. Now, you could compound gear the middle gear, then it would count.
Can you post a picture of the gear train on your lathe?
Hmm, good call...will check it out.
"It is more that each pass seems to run into/over each other slightly, like the tool isn't tracking with the first scratch cut...."
Shepherd, Are you sure the piece is not moving in the chuck? The chuck on some of the machines is not the greatest. Also if the tool doesn't have enough clearance on the leading edge, it will push the stock back into the chuck. I assume you're using a center to support the end of the work? This would help to tell you if the stock is moving into the chuck.
11 TPI is a pretty big thread for my small lathe. .010 cut may be OK for a couple passes, but then you need to take smaller cuts as the chip load widens out (deeper).
Good luck
Ed Hoc
Shepherd, Are you sure the piece is not moving in the chuck? The chuck on some of the machines is not the greatest. Also if the tool doesn't have enough clearance on the leading edge, it will push the stock back into the chuck. I assume you're using a center to support the end of the work? This would help to tell you if the stock is moving into the chuck.
11 TPI is a pretty big thread for my small lathe. .010 cut may be OK for a couple passes, but then you need to take smaller cuts as the chip load widens out (deeper).
Good luck
Ed Hoc