lead screw bronze nut problem

Hi, i recently purchaced a second hand HOBBYMAT MD65 type lathe, it needed a good clean up ,so took it apart few bits at a time , now the lead screw is hard to turn by hand and the bronze nut that sends the compound slide back and forth is not working so the .. the slide will not respond either in manual or motor fed use..can anyone please help with my problem and is it poss to take the lead screw out of the lathe to view the bronze nut thank you alan

The leadscrew is stainless steel, a piece of swarf can get drawn into the nut and raise a burr on the leadscrew. To remove the leadscrew, take off the endplate at the tailstock end, remove the gear and spacer from the left end of the leadscrew, the leadscrew nut is held in the saddle by grub screws, slacken these and withdraw the leadscrew and nut from the right. It's trial and error to find out which way to turn the nut (use the chuck to hold it if necessary) turn it whichever way it moves most easily, use plenty of oil. Clean thoroughly, check for burrs.

Dave

Thank you Dave, i have just spent all morning trying what you said but no luck...there is more to be taken off the leadscrew at the headstock end . i removed the gear and spacer, but the leadscrew will only move 1 inch to the tailstock end if i tap it with a rubber hammer, i have the Hobbymat md65 manual which shows the leadscrew in exploded view,,seems as if the coupling bit / then the gear, followed by the other half of the coupling, which i cannot remove as there is a spring clip inside the coupling which i cannot seem to get out ..then there is a bush held in place by a dowel which i have removed, but can get no rurther until i can remove the spring clip inside the coupling thank you alan

The compound slide, known in the UK as the topslide is the very top one. You seem to be talking about the carriage or saddle in your second post. Are these two different problems?

If you have undone the screws holding the leadscrew nut in the casting as suggested yuo should be able to move the carriage casting to the side exposing the nut without removing the leadscrew. Loosen the clamping screws at the back of the saddle aswell to make it slide more easily. (the centre screw is a forcing screw to push the gap apart but be careful in its use.

As the leadscrew thread is so fine 1mm pitch I find it hard to think it is swarf, maybe gunged up oil so consider trying to get some thinners soaking into it.

Screwfix have an excellent set of circlip pliers in stock at local branches. Way better than the prices would suggest. Not available mail order but many of the local stores seem to have them in stock.

Circlips, internal or external have 2 holes in the ends that the pliers fit into..

Silly thought for you - is there a saddle clamp screw to lock it into position some how? I did have one for a time but can't remember. Watch how tight you fit tools - the screws are perfectly capable of cracking the tool holder casting - as the next owner of mine found.

In my experience it would be very unusual to have a lead screw nut jam but if you disengage the screw cutting and can't turn the handle on the end of the lead screw it is or the saddle is locked.

John

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By the way compound slide is the UK term, top slide the N.American one.

John

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Thank you Bazyle, i have taken out the four screws that hold the leadscrew in place , also loosened the clamping screw in the centre of the saddle at the back,[ the centre screw is the locking screw and the one either side are the forcing screws in my instruction book]. but none of this will allow the saddle to be moved to one side to get at the leadscrew nut..

Tried Bazyles way and reversed what the user manual says and tightened the centre screw to free up the saddle and hey presto it worked, i slid the saddle along the leadscrew which allowed the bronze nut to show, however the nut seems as if its welded to the leadscrew and i cannot shift it at all , tried a whole can of WD40 with no luck..any ideas on what will free the nut from the leadscrew please ... thank you alan PS its a bit hard for me to do all this as i am 82 and 7 weeks ago i sliced through my left wrist with an electric saw so wont be right for at least another 6 weeks if at all as only the little finger is working now

WD isn't very good for releasing things as it is a bit too thick to penetrate. (interesting article in current MEW) One thing is to wrap it in a bit of kitchen towel, damp that down with white spirit, carburetta cleaner, or other thin solvent and wrap in plastic to keep it in. Then leave fro 24 hours to penetrate.

Since it is probably now the morning when you read this for today you might try warming with an electric paint gun to see if that softens the gunge. However you might need to make further attempts to release the whole leadscrew so that you can grip the nut in wooden packing in a vice. Keep the mole grips off it though.

Thanks again Bazyle, will try what you sugested today, i wish i could get the leadscrew out but dont think i can . if all else fails i will have to put it back on ebay as spares thanks again alan

Is it still posible to purchace a new leadscrew and nut for the lathe.or a second hand one??....alan

Alan,

I just found this page, which looks worth you reading.

He also mentions that some spares are available via Essel Engineering.

MichaelG.

Edited By Michael Gilligan on 13/06/2015 09:00:28

A big thank you to everyone for your help and comments, however the work needed to get the leadscrew free and working is beyond me at my age and until i regain some use of my left hand after my wrist accident i feel a bit useless, so will put the lathe back on ebay and sell it for spares or repairs, which is a shame as it cleaned up nicely

thank you all again alan mablethorpe lincs east coast

Before you give up Alan, you might be walking away from a lot of pleasure (and the occasional frustration) s here anyone reading this who is within easy reach of Mablethorpe?

It does sound like someone with a workshop and a little more familiarity with the Hobbymat may be able to get Alan up and running without too much difficulty?

Neil

Alan,

I hope I'm not too late entering this discussion but I live near Boston and have a Hobbymat myself, so I could, and would, be willing to visit you to see if I can do anything to help.

Are you sure it is the leadscrew nut locked to the leadscrew or just that the backlash adjustment is too tight? Leadscrew backlash is taken up by screwing the handwheel onto the end of the leadscrew and locking the handwheel with the nut; it is quite easy to inadvertently tighten the handwheel a little more when tightening the nut - result, leadscrew wont turn (been there, got the T-shirt). Unless the leadscrew is rusty, which it shouldn't be if the lathe has been lubricated, I can't see how a bronze nut could become immovable.

I will email Neil a reminder of my contact details to pass on to you.

Another Alan

Hello another Alan, thank you for kind offer of help, but just a few hours ago i bought a CLARKE CL250M which is just a year old, cost quite a bit but looks near new..i have put the saupe/ hobbymat,,on PRELOVED site as for sale or exchange for a drummond 4" round bed lathe as i have had 2 of these and get on well with them..may even put it on ebay when i take some photos. however if you come this way anytime you are very welcome to call on us in sutton on sea [ kettle always on ] or something a bit stronger...thanks again alan

These are not bad lathes Hobbymat Alan so I feel it is worth sorting out especially if it's just the handle fitting. These lathes are even fairly precise. I found 2 problems, one I mentioned was found by the owner after me - the original tool post casting on the later Hobbymat are a bit weak. The other was prolonged screw cutting. The dog clutch on the end of the lead screw needed some attention. I feel it needs a more robust material but at the time my best source of cheap accurate 1MT arbours was either HSS reamers or drills so it was working fairly hard. The fix was to just run a file over the mating parts.

John

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Hi Alan!

Am not a Hobbymat owner or user, but am a retired Mechanical Engineer, and fairly well equipped.

DON'T junk it until all avenues have been exhausted. (Was the Leadscrew hard/impossible to turn when you bought it? If so, this was probably why it was sold!)

In fixing it, you will learn a lot, and gain a great deal of satisfaction and confidence. AND you will have added quite a bit of value to it.

If all else fails, you could bring it to me, (about 40 miles south of Boston - Neil has my address, and we can arrange by E mail) and i will do whatever will help.

Howard

Thank you Howard, i dont think i can handle this any more in spite of all the help this site has offered me, as i say ,i have just bought a near new clarke 250 lathe which will do what i need a lathe for..due to my wrist accident i am unable to drive far as i have the use of one hand only although the car is a automatic one with electronic brakes, i only go for a 2 mile drive until i get the use of my other hand back [ if ever] I have put the SAUPE / HOBBYMAT lathe on PRELOVED site for sale as offers or exchange for a drummond 4" round bed lathe or similar..so hope that may prove helpfull..and yes the leadscrew was very hard to move when i bought it..thank again to everyone for your help and advice, you are all fantastic alan