Just don't understand then why it doesn't lock up closer to the chuck
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Lathe carriage biting the bed
- Thread starter Suzuki4evr
- Start date
Better Mic it up there has to be wear or chips caught in the slide portion. Guess you'll find out tearing it down to fix.
Is it possible there's just more bed wear up near the chuck and if the gibs are tightened enough to fit well there they are then too tight to pass the sections with less wear farther back? With the gibs loose, does it bind at all?
I took the gibs completely off and it stil binds.
Going by what you described in your first post, I'd tend to agree with Silverbullet that you check the rack (shown near the top of the first photo in post #16). Zooming in on the photo, it looks like there may be some crud on the rack.
One thing you might want to do before going to the trouble of disassembling the carriage or pulling the lead screw would be to wrap the leadscrew with some tape and mark its rotational position. Then rotate it by ¼ turn, check for binding, rotate again, etc. If the binding is the same regardless of leadscrew orientation, I'd suggest the bend is not the major culprit.
-also-
If you engage the gear box and turn the lathe on, how bad does the bend in the leadscrew look when it's rotating? If you then engage the power feed, is there any indication of the carriage binding? Is it in the same place?
One thing you might want to do before going to the trouble of disassembling the carriage or pulling the lead screw would be to wrap the leadscrew with some tape and mark its rotational position. Then rotate it by ¼ turn, check for binding, rotate again, etc. If the binding is the same regardless of leadscrew orientation, I'd suggest the bend is not the major culprit.
-also-
If you engage the gear box and turn the lathe on, how bad does the bend in the leadscrew look when it's rotating? If you then engage the power feed, is there any indication of the carriage binding? Is it in the same place?
The crud you see is actually new grease. The rack is near perfect. The bend looks minimal but the carrige and motor actualy stops and every time at the exact same place. I tried to measure the bend,but it is a bit difficult because of the hex shaft and positioning of it. I got it at +- 3mm-5mm.
Forgot to mention that there is on spot that the carriage is free at that particular aeria and that told me the shaft must be bent.
Shaft straightening is not difficult, just needs a decent setup and patience. Go slowly and try really hard to press on the spot with the most runout, in the correct direction, and try really hard not to overshoot. Keith Fenner has some very good tutorial videos on shaft straightening by multiple methods. I recently helped a friend straighten the X axis lead shaft of his Bridgeport after it had been damaged in moving the machine. It went fine, got it to within a few thou over the 4+ foot length. Again, take your time and keep accurately testing your work, try not to overshoot, and make sure you are pressing on the correct point and backing up on the correct points as you go along. It is much more about testing and thinking than about bending, at least for newbies. We straightened the BP screw on V blocks on my HF 20T press and tested it on V blocks on the work bench using a dial indicator and stand, looking for runout. Do the least amount of actual bending as possible.
Yes Bob it is not so difficult. Luckely I am actually a qualified automotive machinist and have years of experience straightning crankshafts when I did crankshaft grinding amongst other things at the workplace I worked at,but I don't practice it anymore and do lathe work from home after a big motorcycle accident 9 years ago. The worst part will be getting the shaft out. Thank you for you input.
OK. Sounds like you're way ahead of me (which is a good thing!) Best wishes getting the shaft straightened.