Wobbly Lathe – some Advice please

[Ace ChandlerParticipant @acechandler49785]

[Ace ChandlerParticipant @acechandler49785]

Hi – I've just moved house and installed my lathe into my garage (axminster mini lathe)- it's bolted down etc, but I noticed that the carriage seems quite wobbly on the back ways. There is a video below I recorded to try and demonstrate the problem. I should confess it might have always been like that and I've only just noticed!

I noted there are 4 grub screws (2 on the top, and 2 on the bottom) on the carriage at the back – I think these might be the gib adjustment, I've played a bit with these to try and adjust it out, but it's still quite wobbly, even with the grubs in quite tightly.

Also, the "clamp" (apologies if that's the wrong technical term!) on the front ways was pretty loose, so I tightened this up, but it still wobbles on the back ways.

I wondered if I might need to make a shim to take up the slack

Many Thanks in advance.

https://vimeo.com/501507104

[Roger BestParticipant @rogerbest89007]

Looks like it has come off the surfaces and something is stuck underneath – the gibs maybe.

Strip it down before you bend the leadscrew.

[David George 1Participant @davidgeorge1]

There should be a strip bolted to the rear of the saddle holding it down and some thing has either come lose or broken and you need to have a look at the rear underneath before you do any further damage. look underneath for a plate and bolts perhaps something has has come adrift and has got between the bed and saddle.

David

[Ace ChandlerParticipant @acechandler49785]

Thank you – I will take a few more pictures and post back with a response once I've had a chance to look tonight.

[Ace ChandlerParticipant @acechandler49785]

Would anyone happen to have one of these and can confirm if a part is missing or not (SC2)?

 

I took a photo shown below (the excessive red is my poor graphics package!) – but I think there is supposed to be strip under the back of the carriage that bolts in and then overhangs under the ways to keep it down (where the red arrow is). It would be great if someone could take a photo of theirs to show me what it's *supposed* to look like.

 

Thanks much in advance. The help is really appreciated.

 

 

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Edited By Ace Chandler on 18/01/2021 17:14:42

[Andy_GParticipant @andy_g]

Posted by Ace Chandler on 18/01/2021 17:13:11:

Would anyone happen to have one of these and can confirm if a part is missing or not (SC2)?

Yes, there's a part missing – there should be a plate there.

Have a look at the top of page 11 of this document:

https://www.arceurotrade.co.uk/machineguides/C3-Mini-Lathe-Dismantling-and-Reassembly-Guide.pdf

(The whole document may be useful)

The carriage should just sit on the bed with or without the plate. From your video, the carriage appears to be springing off the bed which is definitely wrong. I would be concerned that the lathe has been lifted by the unsecured carriage and something (probably the leadscrew) has been bent.

[Ace ChandlerParticipant @acechandler49785]

yeah , so I've bought some new shear plates (your helpful link tells me that's what they are called) – I'll replace it and then see where I am.

I guess worst case, I might also have to buy a new leadscrew? – does that sound about right, or could any damage be more extensive than that ?

[Dave HalfordParticipant @davehalford22513]

Was the lathe OK before you moved?

The carriage should stay flat on the bed only if the the weight of the rear part is greater than that of the front apron.

The fact that the front bobs up when you wind it on the rack is hopefully you changing the pressure on the hand wheel as you wind it.

It looks like you have over tightened the front clamp too much as well. Loosen it off till the rear carriage bearing surface can return to the bed. If you then lean hard on the centre of the carriage with your left hand where the cutting tool goes you should be able wind the carriage with your right hand back and forth without it rattling about.

I think the plate fell off in the van when you moved.

[Andy_GParticipant @andy_g]

Posted by Dave Halford on 18/01/2021 18:10:46:

It looks like you have over tightened the front clamp too much

That also could be the reason for the carriage springing off the bed. (It's not just cranking, as the movement can be seen at the end of the video where the carriage is stationary – 13 seconds on).

[Dave HalfordParticipant @davehalford22513]

Posted by Andy_G on 18/01/2021 18:38:12:

Posted by Dave Halford on 18/01/2021 18:10:46:

It looks like you have over tightened the front clamp too much

That also could be the reason for the carriage springing off the bed. (It's not just cranking, as the movement can be seen at the end of the video where the carriage is stationary – 13 seconds on).

Agreed, he's got the rear of the carriage waving about in fresh air, it's bound to spring.

[Ace ChandlerParticipant @acechandler49785]

Update – I've reattached the shear plates to the back and things seem to be moderately back to normal.

I actually took most of the machine apart and cleaned and re-tightened most of the bolts (the one on the cross slide was loose too!).

Its much better now, although still a little bit of racking – i.e vertically when you look down from above, the carriage twists very slightly. I'll have to think about how I can trim this as the carriage doesn't seem to have Gib adjustments like the cross slide does. If I tighten the shear plates up too much then you can't actually move the cross slide which isn't optimal

…but it's vastly better than it was (unsurprisingly)

Thanks again for the advice.

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