Cross slide screw worn out?? You be the judge!
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- เผยแพร่เมื่อ 12 เม.ย. 2021
- Watching doubleboost cut a new cross feed shaft and nut got me thinking... (That's always dangerous) So I decided to check mine, Is it time for a replacement? Kinda looks that way to me. Thanks for watching!
Definitely piss wobbly slack
Thanks John! I've got a new one on order!
I'm thinking your screw and nut are perfectly functional as is. If you want to bring your lathe back to "factory" condition, or just looking for a project making a screw and nut for the experience I can see that. I've done that myself. The thing about lathe cross slides is, the movements when in the final cuts are very small usually a fraction of a turn. So any error due to screw wear is almost insignificant. And backlash with conventional screw/nut needs to be managed whether it is .005 or .030. Different situation than cnc where ball screws are necessary. I'll look forward to seeing you make a set if you decide to go that way. Tc, Mike
It's hard to tell how much play is really in it, but usually those nuts are cut oversize by a few thou for clearance, but you have to think that the nut really isnt wobbling around, or it shouldnt be, but it really depends on the amount of play and how much of the threads are left in the nut itself. If you just unscrew the nut off of the leadscrew, you can see how bad it's worn. If it's for the cross slide, then the backlash really doesnt matter tbh, as long as there's enough of the threads there to do the job. I would try snugging up your gibs for the cross slide and compound slide. I like to have my gibs a little snug so that they feel snug to turn in, but not so much that you have to wrench on it. I would check the gibs of the compound and cross slide, they do work themselves loose over time. That'll probably help alot with chatter and with parting issues.
Thanks for the ideas Chirp. I've got my gibs adjusted pretty good and there isn't any real slop anywhere. I do want to put an indicator on the headstock and see if I find anything there. I ordered what should be a good replacement screw and nut today from grizzly. Fingers crossed it's the same stuff!
J
No wonder you want to be in the next town when parting off! I take it the adjustment on the nut is taken as far as it will sensibly go?
Parts not available? Can you get something to suit and adapt it? Those bits are really quite worn.
Thanks for stopping by. The lathe is a Supermax, but it looks like the sister to the grizzly 14x40. I called them today and they didn't have any specs on their screw and nut, so I bought them anyways. I think the best thing to do is replace both at the same time. Next thing I want to look at is headstock bearings. I'll spend some time checking out your method. I'm new to this stuff and having fun learning this machining thing. Thanks again!
Many of the Asian lathe builders don't use good grades of material for parts on their lathes. See this more on the smaller size lathes. South Bend lathes did the same, too. Cross feed screws were made of materials like 12L14 and 1215 grade materials. Yeah, they make pretty looking screws but wear out quickly. I made a cross feed screw for one of the Sheldon lathes I used to own many years ago out of drill rod. Thirty years later, still good as new, so was the nut I made, too. Sheldon was bad making their nuts out of cast iron! Cast iron is not a good material selection for cross feed screw nuts even though lathe manufactures did so. Everyone I've seen where cast iron nut was used, the screw was severely worn, too. The best combination I've used was drill rod, 1040/45 TP & G, or 1144 Stressproof for the cross feed screw, and 660 bronze for the nut. I don't recommend aluminum bronze for nut for the same reason not using cast iron. The smallest bronze nut I have single pointed was for my 9" South Bend lathe about 45 year ago. I don't think I could do it again without messing it up! The nut in your video would be no problem to single point for me. Regardless of what the screw size is, it can always be adjusted to allow use of a standard Acme tap for tapping the nut. Then single point a screw to fit the nut, to get that snug fit you want. And always keep the cross feed screw well lubricated! Don't rely on the Gits oil cup to oil. Ken
Excellent advice Ken. I got in some grizzly parts and they were not even close to what I have, so I sent the screw and nut back. While my screw and nut here are pretty tired, it seems it wasnt the real source of my troubles. I had another look at the rear adjusters and scraped in the front of the carriage for a better fit. I have many irons in the fire at the moment, but would like to try my hand at screw cutting these parts later. Thanks for stopping by!
Hi WT
Yes it is!!!! is that the new term for worn out "Piss Wobbly" I must remember that one. !!! Nice one
regards
mr f
Yeah I think John (doubleboost) started that one. I need to learn how to cut an acme thread and I'll remake a shaft and nut. Thanks for watching!
Mine arrived bent and worn so I fitted an ebay ball screw. I put a ninety degree reverse in gearbox on the end. And I am very pleased with it :D
That's a great idea! I didn't know they make them short enough for a cross slide! Thank you!
@@jagboy69 well, not to bad to cut the end off, but I had to swap ends with the nut. You know how they say don’t strip a ball screw down? It’s good advice :D turns out the balls run in three circles independently of each other. I had to make a sort of fork to hold the nut to the underside of the slide.
@@teamidris I've heard that..
That's more sloppy than the worn out one I'm trying to replace on my father's old artisan lathe. Definitely time for replacements.
That looks like standard ACME thread easy to verify and replace. The old artisan lathe has an oddball thread 3/4"-2TPI LH ACME (probably a stub).
its metric..🙄 I think. I've got one coming from grizzly, hope it's the right one.
@@jagboy69 ACME metric is very common. Should be easy to get a replacement.
@@askquestionstrythings Whomp whomp wahhh.. The grizzly is too short. back to the drawing board.🥺
@@jagboy69 what are the specific specs you need?
@@askquestionstrythings I'm away from it the moment. I'll get some dimensions soon. thanks!
Yep, piss wobbly - mind you mine is f a a a r worse and already on its second nut - next time wil be both nut and screw. For how to part off check out smallcnclathes channel he has a video or two on it. He has converted me to his choice of tooling and now I can actually part straight at full speed without breaking tooling or ripping the work out of the chuck. Parting now holds no terror for me... Martin
Will do Martin. Thanks for the suggestion. I was parting pretty good, but after a couple of "incidents" I've turned a little gun shy.
Probably the nut is worn and the screw has at least some wear in the middle. May want to consider a method that's out there on the internet: replace the nut, or sleeve the center of the nut, with heated acetal/delrin. No personal experience with the method, but it's touted as an easy way to fix the problem. Also low friction and very durable.
How cool is that? Thanks Daniel I learned something new! I did find what could be a suitable replacement screw and nut from grizzly and ordered them today. Fingers crossed they work! Thanks for watching!
@@jagboy69 No problem. Any day that you learn something new is a good day.
That needs to be replaced if it wiggles back and forth. Just the nut. The screw doesn't wear the nut does.
Thanks Bill. I need to try my hand at cutting an internal acme thread one of these days.. Too many projects these days.🥴
Is it the screw or the nut?
Mostly the nut, but there is some wear on the screw in the middle.
I am by no means an authority on such things but I would say you need a new screw or a new note or maybe both probably get away with a new note
You're right, it's in need of a new one. Trouble is can't find it at the moment. I picked up a grizzly and it was wrong and garbage quality anyways. I sent it back. When I have the skills and time, I'll try making one.