hobbymat lathe

[sunnybob]

Hello, I'm new here... :shock: :lol:
I've just acquired a hobbymat universal MD65 lathe.
Its somewhere around 20 years old but has not worked all that hard. Checking it over I found that the headstock bearings needed greasing. the book says 1500 hours, but as I have no idea how many hours the lathe has run, and i dont actually know exactly how old it is, i thought I would like to.

Then i found this lathe needs 2 x C spanners to remove the locking nuts. So heres where you all come in.

Where do i get the spanners from?
do I actually need them?
What direction of thread are they? No thread is visible so I cant just force them with pipe grips.
I'm not precious about the finish if pipe grips will work, just need to know which direction to push in.

Also I would be interested if any body has the angle plate that turns the slide sideways for milling if any one has one.

 

[Harbo]

Can’t help with the Hobbymat, but ArcEurotrade, Chronos and RGD Tools are places I look for lathe accessories.

Rod

 

[AES]

I also can't help with this lathe, but try the Lathes web site (see sticky at the top of this section); and +1 for the comments re suppliers mentioned above (also all in the sticky).

No idea which way those nuts turn, but at a guess I'd say normal RH thread direction, but ONLY a guess ('cos you say there's 2 nuts - probably locking each other). That lathes web site will probably tell you.

Don't know if you can see the nuts at all, but if well enough to measure the dia with a caliper, then it's easy enough to knock up a pair of C spanners out of say, eighth inch steel plate. Proper tools (or tools from the lathe manufacturer, if available) are not likely to be cheap, and are needed seldom.

HTH (just a little bit anyway)!

AES

 

[sunnybob]

There doesnt appear to be a factory website for this one. I have found a couple of mentions, even one who made his own C spanners.
What amazes me is that the manufacturers dont seem to have made or offered for sale these spanners. the handbook gives step by step detailed instructions for removing the spindle, right up to "undo the locking rings". How helpful is that?

I have reasonable access to the collars, they are 32 mm diameter with a 4.5 mm pin. I'm just annoyed that I will have to spend so much time making TWO of them because 1 wont work. But even then, I dont know which way to turn them. I have already tried two pipe grips and got no movement at all.

I have some stainless steel rod that I have turned down to fit. I shall have to go beg some steel today.

 

[AES]

Sorry to hear all that sunnybob. I can just imagine your frustration!

The only other suggestion I can offer before you start making C spanners (sounds like they're "peg spanners" BTW) is to ask your Qs on the Model Engineer/Model Engineer Workshop web site. Again, see sticky at the top of this section.

There's bound to be at least one member on there who knows your lathe. I feel doubtful about offering any more "advice" as I just don't know your lathe - and from the looks of things, neither does anyone else on here.

Best of luck.

AES

 

[J-G]

I have reasonable access to the collars, they are 32 mm diameter with a 4.5 mm pin. I'm just annoyed that I will have to spend so much time making TWO of them because 1 won't work.

I have made my own in the past but not from 3mm sheet, I turned a ring and cut that in half, adding a handle and a pin but that was for a totally non standard collet chuck I built.

Cromwell offer a range of 'Standard' C-Hook Spanners one of which would suit your 32mm Dia. :
https://www.cromwell.co.uk/shop/fastene ... EN5805300K

At less than £22 the pair, that might be the cheapest option. Certainly cheaper (and better) than buying 3mm sheet steel and spending a day fettling!

EDIT --- On second thoughts, why do you need two? Surely there is some way to 'lock' the spindle and then just one C-spanner should unlock the first lock-nut and once that is released the second would unscrew. You would only need a second c-spanner to hold the spindle steady and you would also need another pair of hands to hold that!!

 

[sunnybob]

interesting, but they are in the UK and I'm not.
Also they look like square ended pegs and these collars have 4/5 mm circular holes. The americans call them "pin spanners"

Luckily I have a large metal fabricator in my village and I often scrounge offcuts from him. And its my hobby time, so not such a disaster, even though I would rather be making other stuff.

 

[DTR]

Lots of C / pin / peg spanners on eBay over here, don't know about Cyprus though

 

[AES]

It's purely a guess on my part, but I GUESS the reason he needs 2 spanners is because the outer nut is acting as a lock nut for the inner. In which case, if assembled properly at the factory, the best way to loosen would be to TIGHTEN the inner a smidgen first (while holding the outer still).

But as sunnybob says he doesn't know which hand the thread is, IMO anyway, he'd be better off finding out which hand that thread is before he starts making or buying tools.

I agree that making spanners out of sheet/plate steel is a bit of a faff, a ring would be better, but as it seems now that they're peg spanners and not C spanners, there MAY be a quicker way (e.g. 2 long-ish silver steel bars of the correct dia). BUT that depends on access, AND those pegs are going to have to fit the holes in the nuts pretty nicely (to avoid graunching the nut holes up).

Perhaps a pic or 2 would help our guessing sunnybob, but I still reckon you need some advice from someone who knows that particular lathe before you go much further.

AES

Edit for another thought: A lot of angle grinders use peg spanners to tighten the nut against the disc. have you got an angle grinder? Does your peg spanner fit by any chance?

 

[J-G]

I know we are all guessing - and I certainly made the assumption that the lock nut was the type A in my attached drawing (even though sunnybob said 4.5mm dia!!!).

An angle grinder 'PIN' spanner will have two holes as type C and is unlikely to be used when two nuts are locked together.

I now suspect that Sunnybob has type B.

I also consider that left hand threads are unlikely since the whole point is that TWO nuts are locked together and it's not a matter of potential 'unscrewing' in operation, just a matter of maintaining a location.

 

[sunnybob]

JG... yes they are type B in your diagram.
Diameter 32 mm with three evenly spaced circular holes of 4.5 mm.
Each collar is about 25 mm thick.

They are a bearing pressure adjusting nut and a lock nut.
Obviously there is only one thread on the shaft, but none of it is visible. They did not respond to a fair bit of pressure exerted with pipe grips (in both directions). i have surfed the web and found a couple of "i didnt have the spanners so didnt bother", and one that said he made his own spanners but did not describe direction of turn,so not very helpful.

I've since found out the lathe is even older than I thought, apparently that model was stopped in 1990.
The lathes overall condition is very good but as those bearings havent seen grease for 30 years or more, and there is a very slight rubbing, I want this done.

 

[J-G]

I've just 'Googled' HobbyMat Lathe and found a manual
http://www.bazmonaut.com/wp-content/upl ... nual-b.pdf

Page 20 describes how to adjust the main spindle and says "Unscrew rear nut by turning it in a counter-clockwise direction;"

This confirms (to me) that it is a right-hand thread.

 

[sunnybob]

Thank you for that. I'll use the pipe grips now i know which way to turn them.

 

[AES]

Again, IF it's any help, I agree with JG - my own guess was that since lathes are supposed to happily run in either direction, the chances are high that the headstock thread is a normal RH thread. Especially so since we now see that the nuts are type B (where did you find that diag JG, it's a good'un?).

There MAY even be 3 nuts, which would indicate a pair of bearings, probably ball, maybe even roller type, or taper roller type, pre-loaded (a certain torque setting) then the whole caboosh retained in the head hosing by means of torque loading the outer (3rd) nut. But this is getting complicated, and sounds more like a high-grade industrial machine, whereas I THINK your machine is aimed at the hobby market bob.

All this guess work is NOT good IMO, you really do need advice from an owner of the same lathe, or even better, a Manual for it. Did you try that Lathes web site? Apparently a fount of good lathe info.

Can really only suggest you carry on googling to get the right info, rather than "maybes".

Sorry, can't help more, good luck mate.

AES

 

[AES]

Well found JG! JUST what the Dr ordered!

AES

 

[sunnybob]

After applying a LOT of effort with pipe grips, nothing moved.
Looks like I am going to have to make some spanners. It might even need a hammer as well. Its very obvious these havent been moved before.
DAMN!

 

[AES]

OK, but this sounds like a tough job.

So before going any further, what does the machine sound like when it's running - at all speeds? And if you've got a DTI ("clock") how much run out is there (chuck something you KNOW is round and straight - a bit of silver steel, or at worst any old good really round bar, checked for straightness by holding up to the light against a rule)? If the lathe sounds OK, and doesn't got hot around the head stock bearing housing when running fast, and assuming the run out is reasonable, personally I MAY be inclined to leave the job well alone for a while until you're more comfortable with handling the lathe overall.

By then you'll either have found a suitable spanner/s, or, more likely perhaps, be happy with tackling making you own tooling for it.

Also (sorry if this is teaching Granny to suck eggs sunnybob) don't forget that as this is a RH thread, the 1st (outer) nut is a locking nut, so to get it undone you MUST grip the outer nut quite still - NO turning - while SLIGHTLY TIGHTENING the inner nut. If it was done properly at the factory and hasn't been touched since, you'll NEVER get it undone with just one spanner/pipe wrench/mole grip/whatever.

Good luck

AES

 

[J-G]

where did you find that diag JG, it's a good'un?

Thanks AES - - - it's my original! - SketchUp is so easy

 

[J-G]

So before going any further, what does the machine sound like when it's running - at all speeds? And if you've got a DTI ("clock") how much run out is there (chuck something you KNOW is round and straight - a bit of silver steel, or at worst any old good really round bar, checked for straightness by holding up to the light against a rule)? If the lathe sounds OK, and doesn't get hot around the head stock bearing housing when running fast, and assuming the run out is reasonable, personally I MAY be inclined to leave the job well alone for a while until you're more comfortable with handling the lathe overall.

I concur with that sentiment.

... this is a RH thread, the 1st (outer) nut is a locking nut, so to get it undone you MUST grip the outer nut quite still - NO turning - while SLIGHTLY TIGHTENING the inner nut. If it was done properly at the factory and hasn't been touched since, you'll NEVER get it undone with just one spanner/pipe wrench/mole grip/whatever.

I would like to know what the 'Lock Ring' - - item 26 on page 9 of the manual - - does. I can speculate that it locks the chuck/main spindle but could be wrong. If that is the case then surely with that in operation the lock nut could be unscrewed - - maybe by putting a well fitting 4.5mm dia bar in one of the holes (as long as the hole is at least 5mm deep - deeper would be better) and clouting that with a hammer!

 

[sunnybob]

when the cogs are removed and the chuck spindle is free, there is a slight rubbing from the bearings. No notching or squealing, and no discernable movement.
I'm sure the lathe would still run fine for short periods, but theres enough there to irritate me and for me to want to replace them.

That "lock ring" is merely a plastic shroud "locked" down to the headstock with a tiny slotted grub screw, to cover the back of the chuck from stuff getting wrapped up in it.
The holes are quite shallow, no more than 6 mm deep at most, but there are plastic cogs and pulley wheels all around it. I would need to strip everything out to be safe from bouncing hammer blows.

Its a stupid design to have those collars completely smooth, whats wrong with two normal nuts?
I have quite a lot going on at the moment so this is now going to have to be put back for a month or so. I'm off to the UK in 2 weeks so may just let it go till I can buy the correct spanners.
Luckily I dont have any pressing need to use the lathe just yet.