Vertical alignment of change gears

[Bill PhinnParticipant @billphinn90025]

My lathe gears run smoothly and quietly enough for my liking, but I can’t help noticing, after seeing a similar thing with my milling machine*, a visual issue with the meshing of two of the gears on the standard run/powerfeed gear set-up on my 8×16 lathe.

In the photo the small gear on the second shaft from the bottom isn’t vertically aligned very well with the bigger gear below it, though vertical alignment elsewhere is excellent. My only choice for getting better vertical aligment on this pairing seems to be to bring the gear below it (which is on the end of the lead screw) further in by reducing the length of the sleeve (the black thing). I’m concerned, though, that doing this may create aligment problems of its own with different gears when I start to swap gears around for screw cutting.

Can anyone suggest the best remedy for getting better vertical alignment on these two gears?

*which is still out of action owing to a longer than hoped for wait for the 3D print shop to print me a new gear.

 

[bernard towersParticipant @bernardtowers37738]

Add spacer to smaller gear

[JasonBModerator @jasonb]

These machines can have 2 different thicknesses of washers that go between the banjo and the pairs of gears, get them the wrong way around and you can get the sides of the gears  rubbing oor at the very least not lined up well.

The banjo can also move along the boss it is tightened to so may simply be a case of needing a bit of a wiggle to the left or right.

I did have some photos and drawings in an album on the old site, not sure if I still have them as they illustrate the above.

[bernard towers]

On bernard towers Said:

Add spacer to smaller gear

Thanks for you reply, Bernard.

Unfortunately that won’t work, because even a very thin spacer pushes the gear out beyond the slightly protruding integral stop on the shaft that appears designed to allow the hex nut to hold the gear on to the shaft without preventing it from rotating. Inserting a spacer just means the hex nut tightens down on to the gear itself and stops it from rotating.

A secondary issue with inserting a spacer is that it pushes the gear slightly beyond the full support of the internal bushing the gear sits on.

[JasonBModerator @jasonb]

See his thread starting with my reply here.

[Bill PhinnParticipant @billphinn90025]

Thanks, Jason.

I’ve attached two further pictures showing the whole gear train’s vertical alignment and secondly the mounting shafts on the banjo with their integral washers. There are no free washers between these integral washers and the gears that sit next to them.

I don’t think an extra washer on top of or underneath the integral washer on the shaft the misaligned gear sits on would help as it would a). create a new vertical misalignment, where there was none before, between the bigger gear on the same shaft and the smaller gear on the shaft above it, and/or b). push the offending small gear slightly out beyond the end of the full thickness unthreaded portion of its shaft, which would lock up the whole gear train when the hex nut was tightened down, as I explained to Bernard.

ETA: Yes, I was aware of the importance of properly adjusting the banjo’s side to side position on its boss.

[BazyleParticipant @bazyle]

You do know it doesn’t matter, not even slightly?

[Bazyle]

On Bazyle Said:

You do know it doesn’t matter, not even slightly?

I’m unsure. That’s why I said on the one hand it was a visual issue, and on the other hand referenced my recent milling machine issue, where a vertical gear misalignment definitely did matter. Whilst there may be no current running problems with the gears, does the future likelihood of uneven wear across the teeth  of the gears not matter, even slightly?

 

[bernard towersParticipant @bernardtowers37738]

Why cant you make the spacer longer with a longer gear bush that allows you to tighten the nut ?

[Bill Phinn]

On Bill Phinn Said:

On Bazyle Said:

You do know it doesn’t matter, not even slightly?

I’m unsure. That’s why I said on the one hand it was a visual issue, and on the other hand referenced my recent milling machine issue, where a vertical gear misalignment definitely did matter. Whilst there may be no current running problems with the gears, does the future likelihood of uneven wear across the teeth  of the gears not matter, even slightly?

 

My very similar WM250 puts the gears so close together that if I’m not very careful, they rub on each other which makes a horrendous racket. I’d much rather they fit like yours! Although my long term plan is to replace the whole lot with an electronic leadscrew and bring that part of the machine into the twentieth century….

[HuubParticipant @huub]

This misalignment is common on most Chinese lathes. Luckily you have a lathe and can turn a spacer to get the alignment right.

Turn a “thick” spacer and face 1 side. Put a bar in the chuck and face this bar. Use super glue to glue the thick spacer with the faced side to the faced bar. Then turn the spacer to the right thickness.

You can remove the spacer by adding some heat (torch) or dissolve the super glue using some acetone.

[HopperParticipant @hopper]

Seems like reducing the spacer on the lead screw would be easiest? Or make a whole new spacer of reduced size?

Although, you are unlikely to wear the gears much with the current set up in the short term hobby use. Not much load on change gears in use, unlike drive gears on a mill etc.

[Pete RimmerParticipant @peterimmer30576]

I would agree that it matters not at all, however if it does bother you then view the entire train as a whole. Does the stud gear align with gear A? If so then the banjo is in the correct place and it’s the leadscrew gear that needs moving. Make a shorter spacer for the leadscrew gear, or if there is a washer behind that spacer fit a thinner one.

[Les Jones 1Participant @lesjones1]

On my lathe  (A Chester DB-10G) The studs use two nuts locked together so that you do not have to tighten the nut up to the shoulder on the stud. This does mean that there can be a slight overhang of the gear on the plain part of the stud. This does not seem to cause a problem. I agree with the comments that the slight miss alignment does not matter.

Les.

[BazyleParticipant @bazyle]

Nick W.- fit thin washers between the gears.

[HowiParticipant @howi]

I got rid of my change gears and banjo and replaced them with a cheap version of an ELS. It is not sofisticated enough to do threading but does allow me to set fine or course feeds at the press of a button.

My lathe is now so quiet in use and if I want threads I can always put the banjo back on.

Silence is golden.

[Bazyle]

On Bazyle Said:

Nick W.- fit thin washers between the gears.

I do have a number of spacers to deal with this. But it makes quiet running gears even more fiddly and time consuming which is the worst part of actually using the machine.

[Bill Phinn]

On Bill Phinn Said:

On Bazyle Said:

You do know it doesn’t matter, not even slightly?

I’m unsure. That’s why I said on the one hand it was a visual issue, and on the other hand referenced my recent milling machine issue, where a vertical gear misalignment definitely did matter. Whilst there may be no current running problems with the gears, does the future likelihood of uneven wear across the teeth  of the gears not matter, even slightly?

 

Probably not.   The gears in a mill are part of the drive-train, relatively small, fast spinning, heavily loaded, and subject to shocks.   In contrast, the gears in a lathe banjo only have to drive the lead-screw, which, being a worm, has a massive mechanical advantage.  Thus banjo gears have a relatively easy life unless there’s a crash, when they’re often saved by a shear pin.   I’ve never heard of a banjo gear becoming a problem due to uneven wear, probably because it would take years of hard-work to cause a malfunction.

I had a similar alignment problem on my WM280, and it took me a while to notice that the supplied washers aren’t identical.   The difference isn’t obvious at a glance, nor is it mentioned in the manual, but the gears only align properly if the right thickness washers are put where they need to be.    Try taking the banjo apart and having a good look at all the parts and how they fit together to make sure there isn’t a slight assembly problem due to washers or similar.

The banjo on my mini-lathe was a fiddly chore, but difficult to get wrong.   That on my WM280 is much better, except it’s easy to misplace  washers unless alert to them.   On my lathe the size of the resulting problem varies depending on the ratio,  either not mattering at all, or looking obviously misaligned, or grinding two gear faces together.   Only the grinding is a ‘must fix’.  Your lathe may be different again – the devil may be a detail of the banjo design, as I say not mentioned in the manual!

Dave

[Bill PhinnParticipant @billphinn90025]

Thanks a lot for the further replies.

The consensus seems to be that there is little or nothing to worry about in this case.

If I’m OCD enough in the future to still be bothered by the misalignment, the best remedies seem to be to either fit a reduced-length leadscrew spacer, as Hopper suggests, or produce three new washers for the relevant shaft on the banjo: one a plain washer to go between the big gear and the small, and the other two C-shaped washers, the first to extend the unthreaded portion of the shaft so the hex nut doesn’t tighten down on to the gear itself, and the second to replace the factory C washer, which will be too thick to fit in what will be a reduced gap between the unthreaded and threaded portions of the shaft.

Just to clarify, the lathe came with no loose washers of any kind behind or between any of the gears so any misalignment is not caused by washers of a certain thickness being fitted in the wrong place.

[Neil WyattModerator @neilwyatt]

As long as the gears aren’t interfering, for any slightly misaligned gears that aren’t (semi)regularly removed and replaced, take them off and flip them every year.

Neil

[old martParticipant @oldmart]

Personally, I would not worry, the gears are not transmitting much power.

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Bill, I’ve had my Chester mini lathe for eight & a half years, and mine are are just the same, and haven’t been a problem.

Regards Nick.

[Bill PhinnParticipant @billphinn90025]

Thank you, Neil, Mart and Nick.

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