Hobbymat MD65 carriage adjustment troubles

[Phil PembertonParticipant @philpemberton74433]

Hi,

I'm doing a bit of maintenance on my MD65 mini-lathe, and I'm having a problem with the "forcing" adjustments on the carriage (the three screws on the back).

If I adjust the three screws with the carriage at the tailstock end, the screws require very little movement and will lock the carriage with light fingertip pressure on an Allen key. If I move the carriage to the headstock/spindle end, the carriage will rock when I apply pressure to it.

If I adjust it at the headstock/spindle end, it takes a little more force via the screws to lock down, but the carriage locks up when I move it beyond about half way along.

I'm suspicious that the ways have worn to the point that it's not possible to get a good "compromise" adjustment across the full travel.

Is there anything I can do to improve the ways (match the wear, I guess) to the point where I can get at least a reasonable compromise adjustment?

Thanks
Phil.

[Phil PembertonParticipant @philpemberton74433]

[John HaineParticipant @johnhaine32865]

I think your suspicion is well founded alas, Phil. The only option is probably to lap the RH end of the bed to wear it to the same extent as the LH. You might be able to do that by making a lap? Wouldn't want to use the carriage itself!

I suppose another alternative would be to try to find a piece of ground steel bar the same diameter as the bed and have a flat milled along it, and so just replace the whole thing. From what I recall, it isn't so long so someone with a Bridgeport for example might be able to tackle it?

[Roger BParticipant @rogerb61624]

You should be able to get a new bed. Essel Engineering still have some parts although they are no longer on the website:

**LINK**

As the same lathe is still made and imported by Pro Machine Tools they may also be able to help:

**LINK**

Best regards

Roger

[Phil PembertonParticipant @philpemberton74433]

Posted by John Haine on 09/12/2018 10:11:37:

I think your suspicion is well founded alas, Phil. The only option is probably to lap the RH end of the bed to wear it to the same extent as the LH. You might be able to do that by making a lap? Wouldn't want to use the carriage itself!

I suppose another alternative would be to try to find a piece of ground steel bar the same diameter as the bed and have a flat milled along it, and so just replace the whole thing. From what I recall, it isn't so long so someone with a Bridgeport for example might be able to tackle it?

I'd never dream of using the carriage to lap the bed! Too much risk of ruining the carriage…

I've sent an email to Essel Engineering, hopefully they have a spare bed.

Honestly I have no idea how to go about making a lapping tool, although I probably have most of what I need on hand (wet-dry paper, Dykem and so on). This probably isn't the project to learn it on…

Posted by Roger B on 10/12/2018 14:08:39:

You should be able to get a new bed. Essel Engineering still have some parts although they are no longer on the website:

**LINK**

As the same lathe is still made and imported by Pro Machine Tools they may also be able to help:

**LINK**

Best regards

Roger

Thanks for the info, Roger — I had no idea these machines were still being made! I already knew about Essel, but had no idea they were still around. I might get in touch with Pro Machine Tools if Essel can't help.

Thanks.
Phil

[Roger BParticipant @rogerb61624]

If you can manage German these people also claim to offer spare parts:

**LINK**

There is also a downloadable (German) Instruction manual and parts list at the bottom of the page

Best regards

Roger

[Phil PembertonParticipant @philpemberton74433]

Just to provide an update on this —

I got the lathe sorted out. The problem was a combination of several — grease and filth packed deep into the tailstock and carriage, and unevenly worn ways.

Figuring I had nothing to lose, I removed the right side support and leadscrew bushing. Strangely this part feels like machined plastic, there's almost no weight to it.

The carriage needs to have the locking and forcing screws partly removed before it'll move – so the outer two screws (locking) need to be a few millimetres proud of the carriage casting, while the forcing screw in the centre needs to be removed entirely. At that point the tailstock should slide right off. Use the power feed or refit the handle temporarily to drive the leadscrew and remove the carriage.

At this point I gave the whole lot a good clean with WD40. I put a straightedge on the bed and slipped the feeler gauge in… revealing a depression a few inches from the left side. Not deep, just enough to screw up the locking mechanism in the carriage.

I refitted the right bracket to support it, then ran a 400grit oilstone down the ways to take the burrs off and level it out. After about half an hour of work I noticed the wear-marks in the worn section were starting to give way to the more linear pattern of the oilstone, gave it a few more strokes and called it good enough. Washed the ways down with WD40, gave them a good wipe and relubricated everything with 3-in-1 Oil before refitting the carriage and tailstock. "Reassembly is the reverse of disassembly" as they say.

There's still a slight rock over the worn section, but it's infinitely better than it was.

Now onto the next problem, the previous owner drove one of the support pins for the front carriage support into a blind hole! I'm hoping it's made of mild steel or similar and a magnet might persuade it out, otherwise I'll be turning a drill bushing and drilling the bugger out!

Sadly drilling a 1.5mm hole at the end of the blind hole hasn't helped… my assortment of pointy tools just can't apply enough force to push the pin out.

Oh, and then I have to fit the tumbler reverse… and fix the broken snap ring on the dog clutch…

Cheers,
Phil.

Edited By Phil Pemberton on 28/01/2019 02:14:04

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