Needs Pictures: 0
Picture(s) thanks: 0
Results 1 to 15 of 20
Thread: Tuning out backlash/slop/play?
-
14th Oct 2018, 04:40 PM #1
Tuning out backlash/slop/play?
Sorry guys, I warned you I'd become a pest with my incessant questions...
So, my 260ATM has backlash in the compound handle/collar as well as the cross slide. As you turn the cross slide it takes a few graduations before it starts to take up. The compound is far worse - you can turn the handle from zero past '0.2' and half way to '0.4' before the slop takes up. I know that this is going to annoy the hell out of me.
Is there an accepted procedure for 'tuning out' this slop? Seems to me there must be but I've poked around and can't find it. Any step-by-step advice would be a huge help. I am a lathe newbie but have a life history working with things mechanical, I'm sure this won't be a big problem. I just want my lathe to feel like the precision instrument it is!
So, thanks in advance. I'm off to the shed to make up a forked screwdriver for removing those dome nuts on the handles...
Moz
-
14th Oct 2018, 05:30 PM #2Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,541
The backlash you are describing is between the screw and the nut. If the amount you take the handle up is different at different points in the slide positions (that is, you get say 2 graduations at the end of the slide but in the middle it is more) then it is wear in the screw. If it is pretty much constant, then it is likely that the lathe was made with those clearances. There does need to be some - although some high end lathes were supposedly build without any of this play, if you think about putting a nut and bolt together, there needs to be clearance otherwise it is hard to put together.
If you have different amounts of play, then the solution is to replace the screw. If it is uniform then you either need to modify the nut so it can be adjusted out or replace the screw and nut combination. As I said above, all machine tools have this play and they will operate quite well with it. Nothing to necessarily be concerned about.
I notice that your location is South Australia. If you can be a little more specific there may be someone near who can can look at the lathe and advise a little more precisely.
Michael
-
14th Oct 2018, 07:17 PM #3
Thanks for this Michael. The backlash seems to be constant along the whole travel of the slide. Of course I'd love to adjust it out, but for the moment - as I start out and build experience - I guess I will just work with it. If in 6 month's time it's driving me nuts, I'll have to do something about it. To put it into perspective, I am one of those people who doesn't like play/slop. On my race bikes, if any of the levers/foot controls have any play, I will shim it out so that everything feels right. I can't just let it be, its just not in my nature.
Oh, and to answer your question, I'm in the north eastern suburbs of Adelaide.
Moz
-
14th Oct 2018, 08:50 PM #4Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,541
When in Adelaide I'm out Norwood way, so I'm probably one of the closer forum members to you.
Michael
-
14th Oct 2018, 09:16 PM #5Most Valued Member
- Join Date
- Nov 2007
- Location
- melbourne australia
- Posts
- 3,228
Hi Moz,
I replaced the cross-slide nut on my 260 but I still have a lot of backlash. My problem is wear on the collar of the cross-slide spindle. This doc describes how to fix the problem. I was using my lathe today and cursing the backlash in the cross-slide. I must get around to fixing this myself. I'm surprised your compound has so much backlash, as they tend not to get much use. I suggest you also add a gib locking screw to the cross-slide so you can tighten up the cross-slide for critical operations.Chris
-
14th Oct 2018, 09:21 PM #6Most Valued Member
- Join Date
- Nov 2007
- Location
- melbourne australia
- Posts
- 3,228
-
14th Oct 2018, 10:38 PM #7
Chris, Michael -
Thanks so much for your help and advice, plus that PDF file. Chris, yes, compound much worse than the cross slide in the case of my 260, not sure why. I welcome all and any advice on how to restore, refurbish, improve. Thanks again!
Moz
-
15th Oct 2018, 10:19 AM #8Mechanical Butcher
- Join Date
- Oct 2004
- Location
- Southern Highlands NSW
- Posts
- 1,894
Cutting bits are pushed in one direction to do their job, so backlash is usually not a problem.
A method to reduce backlash is to split the cross nut and have some method to adjust it.
It's not easy to do on a small Hercus, but big lathes often have this adjustability built in.
Wear at thrust collar can be fixed - see Hercus manual.
Modification to include thrust bearings has a side benefit in that the graduated ring tends to stay put when reversing, otherwise it can move unless locked in place with its screw.
-
15th Oct 2018, 07:24 PM #9
Some great advice here nadroj - thanks so much!
Moz
-
15th Oct 2018, 07:48 PM #10Senior Member
- Join Date
- Jun 2016
- Location
- Sydney
- Posts
- 283
Backlash is a historical artifact. You do not have to put up with it. All you have to do is to replace the antique acme thread with a ball screw and ball nut. This is what CNC lathes do.
Yeah, you might need to rebuild the saddle gearing.
Cheers
-
15th Oct 2018, 08:57 PM #11Golden Member
- Join Date
- Nov 2010
- Location
- Gippsland Victoria
- Posts
- 733
-
15th Oct 2018, 09:05 PM #12
Thanks again for the information and opinions, guys!
Moz
-
15th Oct 2018, 09:35 PM #13Golden Member
- Join Date
- Nov 2010
- Location
- Gippsland Victoria
- Posts
- 733
Hey MosquitoGarage,
You might find it interesting to consider making a new cross slide nut by taking the cross slide leadscrew out and melting a piece of plastic around it - sounds daft and crazy I know - but its quite easy to do and well documented on the internet - I have done it on my little 9" Hercus.
If you google Evanut or have a look here you will find out how to do it. There were a few posts on this in the old woodwork forums and a few people tried it.
Making Acetal leadscrew nuts... DIY - Denford Software & Machines
Downside is the plastic nut can be too tight - I wrapped teflon plumbers tape around my leadscrew to give me some backlash in order to make it easier to turn - ironically the melted plastic can have zero backlash and be far too tight to use comfortably.
The melted plastic nut can be very soft, easily scarred by bits of swarf, it can also split but the workaround there is to put a metal sleeve around it............. easy enough to make a new one - google will find various threads and discussions.
Very interesting to have a go and store the knowledge/new skills for future use
Bill
-
15th Oct 2018, 10:03 PM #14
Bill -
Good thinking and for me as a serial tinkerer, reminds me of something I did years ago to repair a drill - I cast the part around an existing thread using JB Weld! I just put Vaseline on the thread first. The result was a tight new part that is still in service today.
I also once cast a small part using silver solder...
Will have a look at this (Acetal method) for sure.
Appreciate the tips. I'm really looking forward to getting to know this lathe and much like my bandsaws and motorcycles, I always find that its the mods and improvements that really make a thing feel 'yours'.
Moz
-
16th Oct 2018, 06:36 AM #15Philomath in training
- Join Date
- Oct 2011
- Location
- Norwood-ish, Adelaide
- Age
- 59
- Posts
- 6,541
They do, and in theory you could convert a manual lathe that way but there are several issues against it -
- Because the nut has recirculating balls in it, it is larger than a typical nut. Refitting to a manual lathe may be impractical just for space reasons
- As ball screws are typically ground and the nut has moving parts, they are not cheap. I always remind people who are considering taking a machine away from a stock condition that you rarely get your money back. If a stock (used) machine is lined up against one where say $500 or more has been spent converting to ball screws, I very much doubt that a buyer will be prepared to pay anywhere near the premium for the modified machine
- Lastly, CNC machines use ball screws for two reasons. One is 'zero backlash' and the other is low friction. You can push on the end of a ball screw and the friction is low enough that it can move. Great for CNC where you have a servo drive always working against that. On a manual machine however it will mean always firmly locking the axis not in use, and/or having to exert much closer to full force resisting the cutting forces.
So while ball screws are technically an option, I wouldn't put them anywhere near the top of the list. I'd probably replace a worn screw/ nut combination with stock parts as a preference or replace the lathe rather than fitting ball screws.
My thoughts anyway.
Michael
Similar Threads
-
Tuning/Restoring of a Shaper Vice
By Brobdingnagian in forum METALWORK GENERALReplies: 36Last Post: 26th Mar 2013, 04:44 PM -
Backlash in Hercus 260 cross-slide
By jack620 in forum THE HERCUS AREAReplies: 15Last Post: 4th Mar 2013, 06:19 PM -
Backlash adjusters
By Bryan in forum METALWORK GENERALReplies: 6Last Post: 27th Jun 2010, 10:38 PM