Cross Slide on Warco GH1330 Lathe

[SamI]

Hi all,

I have been experiencing some intermittent tightness in the hand wheel operating the cross slide (i.e. when taking facing cuts). Initially I thought that the likely cause would have been a bit of swarf that had worked its way in somewhere so I stripped and cleaned the whole assembly (getting the tapered gibs back in was a lot more difficult that it should have been – still not quite worked out why!) but this intermittent tightness still remains. Adjusting the gibs doesn’t do anything nether does adjusting the backlash nut (as it is I’ve got it set up with a large amount of backlash just now as I figured loosening the adjustment would eliminate any possibility of binding here!).

I’ll be turning the hand wheel in when the resistance suddenly increases. If I back it out and go in again this usually temporarily fixes the issue. I was wondering if anyone else has experienced an issue with this?

I suspect that it may be something to do with the washer / bushing shown in the diagram below as part no 673 (taken from a Grizzly manual however the exploded diagrams are closer to the machine I have than Warco’s own!). I think that this part may be binding so part of me is tempted to take part 607V2 and open it out to accept a thrust bearing but firstly, that part may prove difficult to grip in the lathe and secondly, if I remove this from my lathe then I cannot use it to perform the modification! I would also need to investigate whether there is sufficient material to accept the bearing.

Does anyone have any suggestions?

Thanks,
Sam

 

[craptain]

Are you sure that it's the handwheel itself. I have previously encountered a similar sounding problem from badly adjusted gibs, but the feedback can be felt through the handwheel. I know that you just had it all down, but maybe check the gibs anyway and use plenty of oil.

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[SamI]

I have tried adjusting the gibs but I don't notice much difference. The thing that puzzles me is that the feedback felt at the hand wheel isn't consistent whereas I imagine that if it were gib adjustment it would always feel tight in a particular spot? With regards to oil I oil the gibs using the ball oilers after every use. Maybe I should extend this to before and after every use.

I think that there may be an issue with the gib strip anyway as it was almost impossible to re-install after I had it all apart so I guess it figures that the two issues could be related. No matter what I tried it would jam in before I could get the adjustment screws in place and lock the cross slide completely. I hate to admit it but in the end I resorted to a hammer to get it in. Once it was fully inserted the cross slide freed up and the adjustments worked no problem at all. Is there a technique to doing this or is it possible the gib strip itself has warped or is improperly shaped?

 

[BenW]

Tapping it in with a hammer should be fine as long as you can adjust it to a proper tightness once it's in place. Also, use something soft between the gib and hamer or you might crown the end and make it impossible to get back in. As for the binding I'm not sure, maybe check if the leadscrew is bent?

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[SamI]

Thank you both for your suggestions. Luckily the gib screw extends sufficiently that I don't think that would cause a problem although it's probably considered good practice to do that anyway. I'll have it off again at some point and check the leadscrew and the gib again. Knowing what I do now I'm hoping it will be a fairly quick on / off job so if I'm feeling brave when I get home today I'll have a go!

 

[ddickey]

Did you try loosening the cross slide hand wheel nut a tad?

 

[SamI]

Did you try loosening the cross slide hand wheel nut a tad?

Yes, I did adjust this with some success as outlined below.

I stripped the cross slide, cleaned, deburred, cleaned again and reassembled. One thing I did notice was some scoring on the gib strip (see IMG_1359 attached). Not sure how that happened unless a chip had gotten in there somehow. Certainly I can't feel and sharp edges or nicks in the dovetail. I lightly filed the edges anyway just in case a small burr was causing some friction.

I also noticed that during the reassemble the screw holding the handwheel had a grub screw running through it to limit how far it can screw in. This grub screw seemed to be undersized and as such had jammed itself in the threads at an angle. I replaced this with a new grub screw and it certainly makes getting the screw tightened in a little easier (IMG_1360).

Once all was reassembled it felt great - smooth operation for about half an hour then the intermittent tightness came back. I wondered whether my use of coolant was washing away the lubricating oil but further oiling using the oil ports didn't seem to make a difference. I'll try loosening off the screw a little more and see if that improves things at all.

Thanks again for all of your suggestions!

 

[Tozguy]

It seems like you have eliminated backlash in the handwheel and lead screw nut adjustment as sources of the tightness.
Adjusting the gibs is definitely a delicate operation and it can be difficult to get even tension over the full range of crossslide travel due to uneven wear.
Installing the gib with a hammer may have caused the scoring in the picture. If the gib can not be installed by hand using the proper technique then that would be the first problem to troubleshoot and correct.
Any lack of lubrication would be obvious on disassembly and inspection.
I suspect that the screw that stops the gib from going in too deep is not adjusted in far enough thereby allowing the gib to bind. If the tightness only occurs when moving in one direction and not always in the same place then that is my guess for the cause.

 

[SamI]

Thank you for your suggestion. Since deburring the cross slide assembly the gib goes in no problem. I tried re-adjusting the gibs last night with the following observations:

• The screw at the back of the gib was a little loose. I had deliberately left it this way as I read somewhere that having this too tight could actually cause the gib to warp. My train of thought now however is that by having this loose the gib can move back and forth slightly causing it to bind.
• Re-adjusting seems to make little difference. I’ve run it through its travel several times while adjusting and I still get this intermittent tightness. I also gently rocked the cross slide back and forth with the handwhweel whilst gently tightening this screw to ensure that all play had been eliminated while applying minimal torque to this screw.
• I noticed while turning the handwheel quickly that there is a slight noise – it sounds like a gear rubbing on something

So my next steps will be to disconnect the leadscrew nut from the cross slide and see if I can eliminate the source of this noise. I suppose it is possible that misalignment in the leadscrew is causing some kind of binding. Given the noise i suspect that part 667 on the drawing above may be fouling on something.

The lathe is only 6 months old so there shouldn't be any significant wear at this stage. Certainly last time I adjusted the gib I did it with the leadscrew nut disconnected and I didn't observe any binding - it felt smooth throughout its travel. I shall have a bit more of a fiddle about with it over the next couple of days and see if I can suss this one!

Thank you again for all of the suggestions - I feel that I'm getting there slowly!

 

[Cadillac]

To try and narrow down the problem you should eliminate the lead screw. Reassemble the cross slide without screw,adjust gibb and feel resistance. It should move smooth and easily. Then install screw and check for differences.
On my jet 9x20 the allen for backlash in screw was adjusted tight and allowed the wheel crank to rubb on the number dial.

 

[SamI]

With all of your help above I think I've now sussed it!

I believe that it was a combination of factors at play here. The housing (607V2 in the parts diagram in my first post) was sitting too low which I believe was causing the lead screw to bind. I think this could still do with some adjustment as it doesn't appear to be able to move up enough. Alternatively a spacer under the lead screw nut may have a similar effect.

In addition to the above I also loosened off the gib a touch and now the handwheel turns freely and smoothly (possibly a little too freely - I keep overshooting the mark on the DRO!). Still not sure what the rubbing noise is that I'm getting - I think I will save that investigation for another day but for now the lathe is a pleasure to use again! It was becoming a real pain - especially when i am parting because it reduced the feel through the handwheel so I was less able to guage the pressure on the cutting tip (1mm carbide cutting tips break very easily if you're not careful!).

Once again thank you to everyone above for your suggestions - If it wasn't for the words of wisdom I'd probably be posting a thread in the shop blunders section on how not to machine the housing!

Sam

 

[petertha]

Hopefully you solved it. I'm late to your post but another thing that I noticed on my 14x40 is the cross slide 'lock' (if you want to call it that) is basically a set screw that imparts force on the gib strip. When I installed my DRO it gave me valuable insight that the simple act of tightening was capable of moving the cross slide position just a tad via the torqueing action of the set screw. Not good. I fixed this my making a brass intermediary shoe that had the dovetail angle flat on the gib side & a half cup on the other side which was now driven my a new set screw with a bearing ball end. Now the screw pivots effortlessly in the brass part & the 'lock' occurs by pure perpendicular clamping force on the gib strip.

Anyways, blah-blah, that solved my issue. But what I noticed prior to the mod is I had these little arc shaped bite holes in the gib where the screw was basically chewing into it & a raised burr. I knew it was raised because when I stoned the surface smooth I could see small hints of shiny metal. Because of the close spacing in the dovetail, it doesn't take much for some scuffing to go on.