Backlash on Warco GH1230 Carriage

[Martin CurrieParticipant @martincurrie]

[Martin CurrieParticipant @martincurrie]

Hello Guys

I’ve recently bought a Warco GH1230 gear head lathe and I’m absolutely delighted with the machine. One thing I’ve notice is that on the carriage I’ve got almost a qtr. to half turn (possibly slightly more&hellip of backlash on the carriage hand wheel. I spotted this recently when making a slitting saw arbor, I was turning down a piece of stock and was using the power feed on the Z axis, I notice the hand wheel turning for almost a half turn before the carriage began to move. If its backlash I’m not so fussed as this machine has a 3 axis DRO fitted as standard, I’m more worried that there something worn, stripped or loose. When I first started using the lathe, I had to contact Warco for a new brass nut for the cross-slide leadscrew, as it was stripped straight out of the box.

Warco were amazing and replaced the entire leadscrew and nut for me!!

If I wined the handle out and then a turn the opposite direction and engage the power feed the carriage and handle move together immediately.

I’m just a beginner and wat to check to see if its just backlash or could there something else, I’m sure it’s just backlash…

Martin

[Chris CrewParticipant @chriscrew66644]

You don't say whether the machine you have bought is new or used. If it is new a half turn of back-lash seems excessive and even on a used machine a little over the top. Although I have no experience of Warco lathes I can tell you that I consider my Colchester Student to be in excellent condition for its year but the saddle hand-wheel shows up to an eighth of a turn of back-lash when I use the power feed. This is because, I assume, that there is back-lash in the saddle gear-train, back-lash in the rack and pinion and a little slack in the hand-wheel bushes. If your machine is new and Warco provide good service a word in the right direction may help and even if your machine is used they may be able to offer some advice or replacements for worn parts. It seems that you are winding the saddle by hand to eliminate the back-lash and take up any slack so naturally the gearing etc. will not show any slack but you never eliminate it completely under normal operating circumstances because all gearing has a certain amount of back-lash which increase with age.

[Chris Evans 6Participant @chrisevans6]

Slop/backlash on most lathe carriage hand wheels is not unusual. As apprentices we where told to drag our hand on the carriage wheel to stop the lash affecting the finish on final cuts.

[Howard LewisParticipant @howardlewis46836]

Backlash at the handwheel will be greater since there are two lots of backlash involved, backlash between pinion and rack and backlash between the handwheel gear and that driving the pinion.

To make matters worse. the pinion /rack backlash will appear to be increased by the handwheel / gear ratio.

BUT, quarter to half a turn of the Handwheel is excessive, and suggests that there may be another problem.

On my lathe, the gear within the Saddle is pinned to the shaft carrying the pinion. If this pin has been sheared, the lack of security may account for the excessive backlash seen.

If this is the case, the Apron will need to be removed from the Saddle, for investigation and repair.

On my lathe, the Apron is quite heavy, so the procedure is Thanks to Geoff Halstead:

Remove one of the capscrews at each end of the saddle, and replace by a length of (In my case M8&nbsp studding with a nut on top.

Slacken the remaining capscrews, and tap with a mallet ro push the Apron off the rollpins locating Apron to Saddle., before removing the capscrews.

Slackening the nuts on the studding will allow the Apron to be lowered gently onto a block of wood, after which the studding can be removed, ready for replacing the Apron.

The internals of the Apron can now be investigated.

From memory, the pin securing the gear to the pinion shaft was 5mm, (yours may be different ) and will need to be driven through and out of the shaft.

Once separated, burrs /bruising on the shaft and in the gear can be stoned off so that gear and shaft are once again, a good smooth fit.

On my lathe, the pinion shaft was not of a particularly good grade of steel, so the complete assembly was replaced by a shop made 1.5 Mod gear Loctited and pinned onto a silver steel shaft.

The repaired Apron was filled with oil, and lifted back into place by using the studding and nuts, until the capscrews provided the final security.

HTH

Howard  Fat fingers strike again!

 

 

Edited By Howard Lewis on 01/10/2021 13:31:38

[Dave WoottonParticipant @davewootton]

Hi Martin

Might be worth checking that the rack on the front of the bed is securely fixed, some imported lathes rely on the cap screws holding the rack to the bed for location, there are no dowel piins fitted. I worked where we had an Alpine lathe, basically quite similar, and that developed the same symptom. easily fixed by shimming the rack down into proper engagement, drilling and fitting dowel pins.

The lathe was used quite hard machining lumpy castings so I can understand why the rack would move under the hammering it received from unskilled operators. I have used a similar lathe a Warco 1340( I think ) similar but slightly larger industry, and found it to be a very good machine. It was a general use machine mainly used on horrible stainless and aluminium bronze, and had a hard life but stood up to it very well.

Dave

[Martin CurrieParticipant @martincurrie]

Guys…

Thank you all for the comments left over the past few days.. these are all great and I'll have a look as soon as I get home. I'm in the North Pacific at the moment on a ship, so thought I'd use the time here to diagnose and do a little research to determine the issue.

Dave, I never thought about looking at the rack, I've replaced a few of the cap screws that were originally fitted to the lathe as I wasn't happy with the quality of them. I started with the tail stock offset dogged grub screws, one actually sheared and I was fortunate enough to get it out. I replaced these with nice stainless steel grub dogged screws…….

Overall I'm very impressed with the GH1230, its an extremely accurate lathe.

Thanks again guys

Martin

[Mike HurleyParticipant @mikehurley60381]

Agree with Dave W. My old BV-20 had awful play in the carriage handwheel even when new. Had a poke around and determined that the gear engagement was pretty minimal, so, as there were no dowels holding it in place – just cap screws – I dropped the whole rack about 2 – 3 mm. Made a big difference! Don't know if it was bad design or just not positioned correctly at the factory.

Never been perfect, but found I could live with it.

definately worth checking

regards Mike

[BazyleParticipant @bazyle]

+1 for Chris's comment early on. This is normal and common on all lathes. Don't start taking it apart. The handwheel is just for convenience of moving the carriage fast. Check the online version of the manual (find the equivalent machine on the Grizzly site) to find the carriage lock. Whenever you are doing a facing cut lock the carriage – that is why you often see 'modifications' to put a handle on this instead of needing a spanner.
If you are using the power feed make sure you know how to disengage it fast at the end of the cut as if it slams into the chuck or some endstop it does a lot of damage. For safety try to arrange to feed left to right if you can.

[Howard LewisParticipant @howardlewis46836]

Echoing what Bazyle said about running into the chuck, I did, and had to remake the pinion for the Saddle traverse, and remove the rack to remove the damaged teeth.(Prevented any repeats!)

On my BL12-24, the Rack is dowelled onto the bed,by rollpins, so was difficult to remove.

If you can reposition it to reduce backlash between Pinion and Rack,once in place it will be worth drilling in at least three places and inserting rollpins to prevent any future movement.

Howard

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