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Absolute beginner, just bought a cheap lathe

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Chris Drew19/09/2021 16:43:27
6 forum posts
1 photos

Hi All,

completely new to engineering of any kind but always wanted to have a go so I recently bought a Hobbymat MD65 lathe just to have a play and see what I could make. Unfortunately being new and the seller not being up front I have just found out that the cross slide is broken, the captive nuts holding the tool post have pulled out rendering the lathe pretty useless. I want to try and fix this as my first job and was wondering if anyone else uses this kind of lathe and has had a similar problem? If so are there any fixes other than trying to find a replacement? Thanks for any suggestions!

Chris Evans 619/09/2021 20:03:13
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1978 forum posts

I know nothing about your model of lathe but an approximate location my help, there my be a forum member close by.

Grotto19/09/2021 20:43:08
148 forum posts
89 photos

Hi Chris,

There seem to be a few owners of MD65's on here so I'm sure you'll get some help. If you add a photo of the offending part(s) it would be good.

I’m just wondering if it's the cross slide which is faulty or the top slide (which is what tool post bolts to). I may have my terminology mixed up as I no expert.

If it is the top slide, you could just remove it and mount the tool post on the cross slide.

I've done that with my lathe, I just have a spacer under the tool post. I only ever use the top slide for cutting tapers and threads larger then about 1.5mm pitch.

Chris Drew19/09/2021 21:06:02
6 forum posts
1 photos

See, I said I was a complete novice, of course you are correct it’s the top slide which is broken! I had heard of just removing it but then I couldn’t see how the tool post would mount as it uses 2 m8 bolts to attach to the top slide and of course there aren’t any mounting points on the cross slide. BTW i am located just outside Scunthorpe in North Lincolnshire…. The height of the tool post also relies on the top slide so without it the tools would be very low and there isn’t enough adjustment to raise them. I had thought of drilling and tapping the other end of the top slide and just reversing it which I can’t see why it wouldn’t work…

DiogenesII19/09/2021 21:33:47
371 forum posts
169 photos

Hi Chris,

..if you mean the topslide, I don't think it's unheard of for that to happen - mine had had exactly the same problem when I bought it, the previous owner had driiled through, counterbored the underneath, and fitted flanged bushes with threaded holes to anchor the toolpost.

HOWEVER I might be inclined to fit a Helicoil-type thread repair if I was to do the job - it's simpler and results in a repair that is at least as strong as the original fitment - the thread insert may need to be dressed back with a small grinding wheel (Dremel?) after fitting, as the slide is a bit on the thin side.

I'll post some picks of the repairs to mine in the morning.

They are good little lathes, they have a few quirks but are capable of doing very respectable work - although they are well built, they are susceptible to damage if mistreated - it's definitely worth buying a manual, and having a look through previous threads using the 'search' box at the top of this page..

Bazyle19/09/2021 21:55:46
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6085 forum posts
221 photos

The original round toolpost is a bit odd anyway. People do try to do the tool clamping bolts too tight so can damage stuff. Plus the slide is quite thin and flexible so if you overdo it the casting bends and jams.

Pete Rimmer20/09/2021 06:20:54
1096 forum posts
69 photos

I would go with the above solution and helicoil the stripped holes. First though I would put a straight edge across the slide top and make sure it isn't bowed out slightly from whatever abuse caused the stripped threads.

Grotto20/09/2021 08:00:06
148 forum posts
89 photos

Hi Chris,

I made a packing block out of a lump of cast iron.

His attaches to the cross slide the same way as the top slide did, and is drilled & tapped to allow me to bolt my tool post to it.

Toolpost
I'm surprised at the improvement in rigidity with the top slide gone. It was only meant to be a temporary set up, but it’s become fairly permanent.

DiogenesII20/09/2021 08:06:50
371 forum posts
169 photos
Posted by Chris Drew on 19/09/2021 21:06:02:

...I had thought of drilling and tapping the other end of the top slide and just reversing it which I can’t see why it wouldn’t work…

If you do that, it'll put the gib on the 'thrust' side of the slide and the forces of cutting will be concentrated on the points of the adjustment screws that bear on the gib strip..

For the record, here are photos of an ugly repair that had been carried out by a previous owner of mine - the bolts securing the tool holder are M10, which suggests to me that it probably wasn't his first attempt..

FWIW having slept on it, I stand by the Helicoil suggestion..

Topslide

Topslide below

Flange depth

whole bush depth

Ady120/09/2021 09:33:34
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4827 forum posts
724 photos

I bought a total dog as my first lathe too and it took me a long time to sort it out

You'll get there in the end but it will hold you back in some respects

On the other hand it will teach you whether you want to keep going with this hobby, even with decent gear it's quite a long hard and winding road

GL

Chris Drew20/09/2021 10:17:21
6 forum posts
1 photos

I suspect this is beyond saving - when I got it the captive nuts had been welded in but the weld had lifted so the tools could not be mounted securely. Tried re-welding but it's not the easiest material to weld and although it looked OK obviously had not penetrated the material as just lifted again. I do have a similar thickness plate of steel from my hydraulic press which I am thinking I could modify to make a fixed mount for the tool post.

lathe1.jpg

John Hinkley20/09/2021 10:22:56
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1199 forum posts
393 photos

Chris,

I can't help with the Helicoil, which I venture to suggest is your best solution, but once you've decided on a course of action and if you need further assistance, I'm not too far away from you just east of Doncaster. If you require any help, drop me a PM with your contact details and I'm sure we can arrange something.

John

OOH!  Just posted and seen your photo!  Now that HAS been butchered, hasn't it?  I think you'll find that the topslide is cast iron - so difficult to weld.  You might get away with a brazed repair, but it won't be pretty.  If I was you, I'd look around for a replacement in better condition.

Offer still stands, though.

 

 

Edited By John Hinkley on 20/09/2021 10:27:36

Phil P20/09/2021 10:45:27
790 forum posts
194 photos

Just thinking aloud here......but is it possible to reverse it and fix the toolpost at the good end ?

Phil

Ady120/09/2021 10:47:04
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4827 forum posts
724 photos

That's a mess, a replacement could be hard to find as well

Gasless mig can sort cast iron but you need to get going asap or you'll lose interest

Dump that top slide to one side and make a toolpost for the cross slide which will do 90% of your work anyway

This is an early version I did for myself

Nicholas Farr20/09/2021 11:50:52
avatar
3057 forum posts
1387 photos
Posted by Chris Drew on 19/09/2021 21:06:02:

See, I said I was a complete novice, of course you are correct it’s the top slide which is broken! I had heard of just removing it but then I couldn’t see how the tool post would mount as it uses 2 m8 bolts to attach to the top slide and of course there aren’t any mounting points on the cross slide. BTW i am located just outside Scunthorpe in North Lincolnshire…. The height of the tool post also relies on the top slide so without it the tools would be very low and there isn’t enough adjustment to raise them. I had thought of drilling and tapping the other end of the top slide and just reversing it which I can’t see why it wouldn’t work…

Hi Chris, at a last resort you could reverse the top slide and drill and tap the other dove tail to keep the gib strip in the correct side, the downside is the the single hole ((at least on mine) is in the wrong place to get the two holes for the tool post in the same position and you would have to be a bit precise for the little hole for the gib strip pin. The single hole could be used for one of the holes for the tool post but that will mean it will be a little further back and as a result the top slide may engage with the rotating chuck before the tool that you would be using reaches the point that you need to take a cut too, but you could cut the top slide a little shorter, which would be about 6mm to come off, but of course you would loose 6mm of travel of the top slide as well. You can always glue or screw a piece of sheet metal over or those wrecked holes or even use body filler or similar, to stop swarf etc. getting all over the winding thread and filling the cavity.

Regards Nick.

Dave Halford20/09/2021 12:58:59
1820 forum posts
19 photos

I would cover the hole with a 4mm steel plate held down with four off m6 counter sunk screws into the good iron avoiding previously welded surface as it may be too hard, not too near the dovetails. Then drill two holes in the plate m10 clearance, welding two m10 nuts underneath the plate.

You need sufficiently flat surfaces for this to work properly or you end up over tightening so check the plate for warps before continuing.

My experience with cast iron and welding - you lay some weld on cast and hear a tinkling sound - thats the weld breaking.

You use cheap 90% nickel rods with iron (FE) in them , they weld OK but the weld is too hard for HSS tools. Use expensive 99% nickel rods and everything is good to go.

Chris Drew20/09/2021 13:26:27
6 forum posts
1 photos

Thanks Dave, my limited knowledge would suggest that now the tool post would be too high and I wouldn't be able to lower the tool enough to centre. I have found a piece of 15mm plate of the correct dimensions and I think for now I will modify this to act as a fixed top slide. I can then look around for another top slide but having read a little more it seems this is a common fault with this machine.

I don't want to take too long to get up and running as otherwise I may get bored and just give up! I'm certain I will have a load more questions!

pgk pgk20/09/2021 14:29:19
2366 forum posts
293 photos

Depending on how it looks like underneath (for room) and how large the base of the toolpost is.. Would it be possible to mill out a neat rectangle that removes all the nasty holes and a rebate around it underneath, then make up a plate the same thickness with shoulders the depth of the rebate, drilled and threaded and mount the toolpost on that? Locktite it in so it doesn't fall of if you remove the toolpost bolts completely.

pgk

Howard Lewis20/09/2021 14:42:15
5562 forum posts
13 photos

If you contact, and preferably join, your local Model Engineering Club, someone there will probably be able to help you.

It may either be possible to machine away the damaged ares and insert new material, or even to make a complete new Top Slide.

Find out where and when they meet and go and visit.

You will like minds there who will be willing to help and advise you, not just on this problem, but others that you will encounter non journey into Model Engineering.

If you give your location, there may be someone on the Forum who would be able and willing to help you.

Howard

Nicholas Farr20/09/2021 14:50:16
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3057 forum posts
1387 photos

Hi pgk, that would have most likely worked, but if you look at DiogenesII's first photo, you will see that the tools and any shims required sit on top of the slide and the way Chris's one has been attacked with a grinder, won't produce a very good surface for them without a significant overhang.

Just had another look at mine and you wouldn't get a piece wide enough between the dove tails for it to have any surface for the tool to sit on width wise and you would more than likely to have to have it right to the front end for any tool to sit on in that position.

Helicoils or the "Ugly repair" DiogenesII has shown, would have maybe, been the best solution if done in the first instance.

Regards Nick.

Edited By Nicholas Farr on 20/09/2021 15:08:38

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