New lathe arrived today : The ongoing saga

[Brian JohnParticipant @brianjohn93961]

Neil : by ''fully wound in'' do you mean closest to the operator ?

Mahgnia : screw 234 DOES have a tapered end….a sharp point in fact. The bush 245 is not eccentric.

[mahgniaParticipant @mahgnia]

Brian,

OK, to do what Neil says, loosen 232 and 220, wind the cross slide out towards yourself as far as it goes, and then tighten 232 first, and then 220, checking that the cross feed screw can be rotated freely from the dial.

The cross slide should now move smoothly over its whole range.

If there is more than 1/4 turn of backlash, you could then screw in 234 bit by bit to reduce the backlash, but don't do this if you do not need to.

As an aside, when doing normal turning on the lathe, it is wise to have the tool where it contacts the metal of the workpiece at such an angle that the cutting forces push the toolpost/cross slide back against the feed screw. This can improve the finish and accuracy of the workpiece substantially, as any backlash in the crossfeed screw will be automatically eliminated, preventing unwanted movement into the workpiece.

Andrew.

Edited By mahgnia on 17/10/2015 12:41:48

Edited By mahgnia on 17/10/2015 12:42:37

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John W1 on 17/10/2015 10:53:07:

I would suggest you leave the gib strip alone.

.

Over to you, John

I see no point in us giving conflicting advice.

MichaelG.

[AjohnwParticipant @ajohnw51620]

Posted by Michael Gilligan on 17/10/2015 12:43:45:

Posted by John W1 on 17/10/2015 10:53:07:

I would suggest you leave the gib strip alone.

.

Over to you, John

I see no point in us giving conflicting advice.

MichaelG.

If he wants to then can do what ever with it. When I have had a problem with one I find some one with a surface grinder as I know that I will have problems keeping it flat. I could blue it against a surface plate too.

Neil's advice – the nut is set it when the it's as close as it can be to the mounting of the lead screw and assumes the lead screw can bend if there is any angular error when it's further away. It sound and looks like it was set up more or less as I mentioned so that it can track the lead screw moving up and down or rotating slightly as needed. That way does assume that the round bit sticking out of the nut is a decent fit in the hole it goes into. Or maybe it's part set via screws.

The backlash adjustment looks like the usual gash across the nut leaving a short length of thread that can be crunched up against the longer length – but the screws don't seem to be there. They do this on Pulta's but even then it has the same problem – the length that can be moved about is much shorter than the other so wears away rather quickly if used. My own view is that say there is 1/3 of a turn back lash then 1/3 of the nut has worn away less any clearance that was there – time to thing about a new nut. But it will still work with 1/3 of a turn back lash. it will with 1/2 a turn too, even more. Most people who have used machines much take out back lash when they make adjustments without even thinking about it. In fact I use over a turn to do that even though none of my machines have more than 1/10 of a turn back lash.

John

–

[Brian JohnParticipant @brianjohn93961]

I am wondering what I did wrong today when lapping the cross slide ? I could feel the tight spot in the middle and I worked on that, tightening up the gib screws slightly as I went. As this tight spot slowly disappeared then I gradually began moving the cross slide over the full range until everything felt even. Granted, the slide will be moving twice as much in the middle as at the ends, but everything felt even and smooth across the full range. That SHOULD have resulted in everything being even and smooth when I reassembled the cross slide with its lead screw. Unless of course 230 and 232 have not been adjusted correctly.

Should I have stopped once I had removed the tight spot from the middle rather than try to lap across the full range of movement ?

It is past midnight here now so I will have to wait until the afternoon to have another look at things.

[Neil WyattModerator @neilwyatt]

There will be enough play in the fixed bearing to compensate for any small misalignment as the nut moves away. By adjusting it when it's near the fixed end of the screw, the amount of movement will be minimised.

230 locks the nut in alignment, 234opens up the slit in the nut to reduce backlash.

Neil

[Brian JohnParticipant @brianjohn93961]

Neil : you mean 220….not 230 ?

I could not wait until later so I have tried adjusting 232, 234 and 220 ; nothing makes any difference. 234 in particular does not seem to affect anything. Maybe it should but it doesn't !  The only way to remove the excess play is to tighten up the gib screws to the point where it is hard to turn the wheel. Even backing them off by 1/16 turn introduces too much play…very frustrating as it did not have this problem last week. I do not know what has changed.

I will have another go at lapping : just 10 minutes to remove the tightness at the operator end and then reassemble. I have to try something.

I think I can assemble the cross slide blind folded now. Is there a prize for that ?

Edited By Brian John on 17/10/2015 15:42:13

[Neil WyattModerator @neilwyatt]

Yes, sorry, 220.

Put it all together when not fitted to the lathe, and see if there's any slop in it, plus see if you can feel 234 opening up the sloit at all..

Neil

[mahgniaParticipant @mahgnia]

Posted by Brian John on 17/10/2015 15:39:15:

I could not wait until later so I have tried adjusting 232, 234 and 220 ; nothing makes any difference. 234 in particular does not seem to affect anything. Maybe it should but it doesn't ! The only way to remove the excess play is to tighten up the gib screws to the point where it is hard to turn the wheel. Even backing them off by 1/16 turn introduces too much play…very frustrating as it did not have this problem last week. I do not know what has changed.

Brian,

Where EXACTLY is this excess play you speak of?

1. The gib screws should be adjusted to eliminate play (sideways, twisting) between the cross slide and the saddle only, but allow the cross slide to freely move along the saddle dovetail.

2. the screws 232 and 220 should be tightened as per above (temporarily leave 234 loose) to fix the nut 213 firmly to the cross slide.

3. the cross slide feed screw dial should be mounted on the cross slide screw to minimise the end play between the screw and the cross slide, but there should still be some clearance (end play) there (this is OK, necessary for lubrication and free rotation of the screw)

4. the cross slide feed screw should rotate freely in the nut 213, but screw 234 can then be screwed down to an extent that the rotational end play in the cross slide feed screw is reduced (this is the backlash adjustment). Some end play (which shows up as rotational backlash) is still desirable here for the reasons stated in previous posts.

Items 3 and 4 above will show up as front to back slop (backlash) in the cross slide movement on the saddle, but this is not important compared to any movement left from item 1, as cutting forces should automatically take up this front to back movement. The only place where this backlash may become important is when the cross slide dial feed direction is reversed (winding the cross slide back out from the workpiece), and this should be accounted for by winding the cross slide out further and then winding back in to your setting taking out the backlash. This is normal for nearly every lathe.

Hope this is helping, and not muddying the issue.

Andrew

[julian atkinsParticipant @julianatkins58923]

i think that Brian is very well acquainted with this lathe by now!

it is rather depressing that such an inferior product should be marketed and sold.

many of us would be able to sort out the problems to rectify the lathe and bring it up to spec, but is it really sensible to suggest that Brian, as a beginner, could undertake or be expected to undertake this work? 'fettling' and 'fitting' is pretty skilled work requiring a knowledge of 'what's what' etc. i think that this sort of job is way outside what Brian out to do on a new lathe. i certainly wouldnt have been able to do this when i was a tyro.

cheers,

julian

[Brian JohnParticipant @brianjohn93961]

After much fiddling and adjusting I have given up on trying to get the cross slide to move evenly across its full motion. For now, I will live with it ie. the cross slide must constantly be checked for unwanted movement and the gib screws adjusted accordingly.

The movement I am talking about is grabbing the cross slide with my hands and being able to move it back and forward along the lead screw by as much as 3mm ! You cannot turn anything with that much movement. The only way to get rid of it is to tighten up the gib screws to the point where the hand wheel is hard to turn. Backing the gib screws off even 1/16 of a turn is too much and causes the problem to occur again.

I thought adjusting 220, 234 or 232 might give me good results but I have had no luck there at all. 234 in particular is puzzling : it does not seem to make any difference how tight or loose it is. In the end I left it where I had found it : with the tip just in the slot of 213.

Time to get back to actually using the lathe to make something.  I cleaned up some large (30mm diameter) brass bars I found at the scrap yard. All turned and faced off in manageable lengths of 100mm…good buying for $6  !

What really annoys me is why they can't sort these things out at the factory. With Chinese wages so low it would only add a few dollars to each unit to have an experienced person spend two or three hours and go over it thoroughly. People will happily pay for quality.

Edited By Brian John on 18/10/2015 08:36:02

Edited By Brian John on 18/10/2015 08:38:42

[JasonBModerator @jasonb]

Brian when you get this 3mm front to back movement do you see any gap opening and closing between the handwheel dial and the carrage casting or handwheel and its dial.

What you seem to be describing is massive backlash rather than a problem with the ways/gibs.

[Brian JohnParticipant @brianjohn93961]

No, there is no gap there.

Edited By Brian John on 18/10/2015 08:40:27

[HopperParticipant @hopper]

Brian, did you order that faceplate? When it arrives, you should bring it and your lathe out to my place and we can machine the recess to fit your lathe spindle and I can take a look at the cross slide for you. I have all the gear necessary to get a good handle on what the problem is and should be able to sort it out for you. There are a lot of small details that need attending to in those slides, which I can go through for you. I would not keep lapping it any more in the hope that it will come good. If one part is fubared, it will end up grinding the other part into a similar condition. It may well require filing and scraping into shape, which is not an exercise for a beginner but will not take me too long to do. (Finally, the months and months I was forced to spend filing and scraping blocks of steel into shape as a toolrom apprentice comes in useful!) I've got a nice plate-glass surface table, and a dial indicator registering 10ths of a thou so we should be able to get it worked up into better shape than you are describing now.

[Brian JohnParticipant @brianjohn93961]

Thank you Peter, The face plate is on its way. I will let you know when it gets here. I think it will be another two weeks or so.

Yes, there is no point doing any more lapping. I am still trying to work out what I did wrong and why it did not end up even across the full movement when I put the cross slide back together. It WAS even across the full movement when I was lapping it ; I had removed the tight spots and it felt perfect.

[HopperParticipant @hopper]

Brian it might be better to give me a call and bring your lathe out sometime this week, rather than wait for the faceplate to arrive. I'll need to have the lathe in my workshop where all the gear is available to properly go through the slideways and mechanisms one step at a time and see what we are dealing with here. It may take several days to work through everything and sort it out.

[Brian JohnParticipant @brianjohn93961]

Okay Peter, I will do that. I will first cut some discs for the Stirling engine cranks so that I will have something to do while the lathe is away. I have the drill press now so I can do a better job on them.

Edited By Brian John on 18/10/2015 11:57:58

[HopperParticipant @hopper]

Posted by Brian John on 18/10/2015 11:57:36:

Okay Peter, I will do that. I will first cut some discs for the Stirling engine cranks so that I will have something to do while the lathe is away. I have the drill press now so I can do a better job on them.

Edited By Brian John on 18/10/2015 11:57:58

No wuckers mate.

[Brian JohnParticipant @brianjohn93961]

The lathe stopped working again today. More problems with the lead screw. I thought it might be problems with the clutch again but after taking that apart again I realised it was working okay. The problem is still with that bushing 303 : this time the lead screw will screw out but it will not screw in. No amount of fiddling will get it to work properly. Any suggestions ? It seems so simple but I cannot see why it will not work.

 

Edited By Brian John on 22/10/2015 08:20:47

[JasonBModerator @jasonb]

Check the carrage is unlocked and you should just be able to slide that to the left which will move the leadscrew and bush with it. Power feed should be disengaged so the dog clutch does not hit end on.

[Brian JohnParticipant @brianjohn93961]

Power feed is not engaged. Carriage lock is not on. It will not wind in ie. carriage will not move to the left.

[HopperParticipant @hopper]

Sounds like something not lining up in the dog-clutch mechanism for the power feed. You might try rotating the lead screw and feeling if you can get it to drop into the slot in the dog clutch. Or pull the dog clutch mecanism out that you worked on before and see what is going on with it this time.

[Jeff DaymanParticipant @jeffdayman43397]

Isn't the handwheel supposed to be up against the end of the base casting, that is, should there be a gap between casting and handwheel? Just wondering if the bushing has slipped out and dropped and is jamming things.

Just a guess, not familiar with these lathes. JD

[Brian JohnParticipant @brianjohn93961]

That is what I thought : something wrong with the clutch so I pulled that part out to have a look. But even when the lead screw is disconnected from the clutch that wheel/bushing set up will still not work. There is nothing much to it so I cannot see what could go wrong with it.

I have to go to work now so I cannot look at it further until tomorrow afternoon.

Edited By Brian John on 22/10/2015 12:28:24

Edited By Brian John on 22/10/2015 12:28:38

[frank brownParticipant @frankbrown22225]

Looking at at Johnw W1 post of the 26/092015 09.11.26 with the exploded diagram, the bush 304 should sit completely inside the moveable scale (304). This will bring the scale up against the marker on the cast in bracket. I think what is happening when you tighten up the knob fixing nut, its compressing the whole assembly via the bracket on to the lead screw, so it all binds.

Paint is not a good bearing surface, so I would strip the end down, fit a tight, thin metal washer up against the main lead screw thread, a gob of grease, then a thin plastic washer (cut out from the lid of a margarine container). Poke the leadscrew throught the hole. Fit another plastic washer, gob of grease, then spacer 303, then the rest of the knob assembly which must sit over and hide the spacer, push it up tight to the bracket. Inspect the amount of thread that is protruding where the nut fits. If its too long there will be a lot of slop, if its too short then tightening the nut will cause it to bind. If you cannot get the spacer to sit inside the knob properly, inspect both for burss, dinks, shallow depth holes, over size spacer diameter and correct until it fits.

Frank

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