This is embarrasing

So I first post a couple of weeks ago with a milling machine problem which ended up with stripped gears (my fault of course, not due to any advice).

Now I need to post with a lathe problem which appears to be stripped gears.

Basically I had a big but of steel rod (90mm diameter and about 120 long) mounted in the chuck rotating at moderate speed and got a bit too quick with the cross slide.

As with the first post, the metal came from a scrapyard and for all I know it's mega hard. NO more scrapyarding for me!

The low gear appears stripped - high gear engages and works, low gear doesn't spin the spindle or catches occasionally.

My options are to send the lathe back to a professional or to have a go.

I'm not keen on the send the lathe back. I'd either have to drive halfway down the country (twice probably) or spend a fortune on carriage - all for a 5 pound gear.

Before I attempt this (or decide to attempt this), I wanted to see what I would need to do the job.

The lathe (SPG0618A from SPG tools in Hinckley) is similar to the C3 as sold by Arceurotrade which has a lovely disassembly guide here .

I expect the process is much the same, though I am by no means certain the parts are compatible.

From what I can see I would need a press of some kind and something to hold onto the bearings whilst they are being pressed out.

Does anyone have a suggestion for a suitable press? Is there anything else which I should think about? Should I look to replacing with metal gears (if SPG Tools or someone else has them)? Should I bother with the bearing swap which Arceurotrade offers? I must say I don't seem to have much chatter and so on.

Or, having shown my ineptness, should I give in and get a proper engineer to sort it?

Iain

Wow that's a very interesting guide. But I'm not seeing a low gear in there. Are you saying you have a backgear? or is it the common system of a variable speed motor and two belt options to give 2 speed ranges?

Alternative method of getting the bearings out here if you have a big hammer

Problem with changing to steel gears if that teh plastic ones are the weak link that will fail before you damage more expensive parts, steel gears won't fail so you damage the expensive bits

Best to fit the steel gear to the spindle and leave the plastic ones on the layshaft.

Reason being the plastic ones are a 'fuse' and the layshaft gear is easy to replace compared to the spindle.

Ian,

I agree with Jason about going the metal gear route.....might be ok on the mill, where there are other sacrificial gears, but the lathe is direct by belt, unless you put a shear key in one of the pulleys made from soft material....

That said, to have to strip out the spindle each time a gear breaks isnt really ideal....

Best option I can offer is to install metal gears and go the soft key route that is external to the headstock innards.

Soft brass for a key, suitably fashioned?

As for spindle removal, using a hammer isnt a good idea.....you may knock out the headstock alignment...( unless you want to re-align it anyway..)

Fabricating some removal puller is the way to go, you could jack the spindle out by using a length of threaded bar through the middle, a piece of tube over the chuck flange resting on the headstock, the other end bearing on the spindle ( with a soft alloy washer)

I replaced the bearings on my Super C3 without any hassle, this way....

Good luck with whatever option you choose

if things need warming up, a hot air gun...

There are 2 x plastic gears within the headstock. Strip and removal is straight forward and its a very simple set up:

If you remove the two adjustment nuts (rings) from the back of the headstock, this is the cheap and easy way to pull the spindle out:

There's a big washer over the other end of the studding at the back end of the spindle.

The bearing might stay behind in the headstock, or come out on the mandrel. personally., I'd use this as an opportunity to swap over to roller bearings, but if not re-assembly just means pulling from t'other end.

Neil

Having done the same thing on my mini lathe . I would contact Simon at SPG and he'll send you the gears unless you want to fetch them and fitting is both straight forward and easy . The"c" spanners for er 25 collet chuck works fine for taking apart /refit

Hi Iain,

Just some bits of clarification. You have put the wrong link in the original post.

The link you have put is for an SC3 (Super C3 lathe), which is a BRUSHLESS motor machine with belt drive. It does not have any high/low gears, as torque is governed my the circuit board on those machines.

Your SPG lathe is close to a C2 lathe. It is not a C3 which is BRUSHED motor driven with high/low gear. We do not sell the C3 BRUSHED motor lathe any more either. It does get confused with the SC3 (Super C3) lathe, and as a result, some competitors do take advantage of this confusion.

Anyway, C2 and C3 BRUSHED motor lathes are close to each other. This is the link to the dismantling guide for the C3 BRUSHED motor lathe.

for everything else, refer to the comments on this thread.

Ketan at ARC.

I have also had the same issue. Not hard to do but does require removing the Headstock.

Neil has the right idea for removing the Lathe Spindle. A Bolt Press.

Any kind of knocking tool is not required and should not be used for the spindle.

You may also need to remove the Counter shaft that the other gear slides on. That shaft is Keyed and can be gently tapped out once the circlip is removed from the chuck side. The Rear bearing will come out with the shaft.​

Assembly is a simple reverse process.

Just follow the ARC guide it is not that difficult to do I have had to do it on both my Warco lathe and Mini mill.

Use a fuller like Neil suggests and you will be fine. I think you will have more problem getting the motor and belt to stay lined up whilst you achieve a suitable tension. I needed a 2' bar with a box off lead hung off the end as a thrid hand to lever the motor down whilst my hands did the rest.

Also if you do take it to bits take EVERYTHING out of the casting head and give it a good rub down inside and wash out to make sure there is no sand or swarf left over from the manufacturer.

regards Clive

Thanks for all advice.

I've got the replacement gears from SPG and Simon kindly talked me through the process.

Today (end of work), I started to strip it down. I've got the headstock off and paused. Of course SPG is now on holiday until next year. Since I am as well, I can't really complain....

However (there had to be a however...), I find my notes after this point reasonably unintelligible.

I think I've got to the point where Simon said to drift the spindle out with a hammer (or, of course the clever fuller Neil proposes). MY tentative taps with a small hammer (with a piece of wood in the way) have moved nothing. I can't shift the layshaft either,

As a beginner, I'm a bit scared of braying the damn thing so hard it breaks, so I thought I would seek some advice.

Here are some pictures

I think this is as stripped down as it gets. I don't think I need to remove the bearing covers - the bearings can stay in place when the spindle comes out.

I suspect that the next phase just involves brute force (applied by hammer or by a press), but I would appreciate advice before I break if further...

Iain

Iain

Leave the hammer in the rack. Do as much online research as possible but use sound judgement. Be aware that some of the videos online can and do represent brutally unacceptable techniques. Pressing out spindles, bearings etc is primarily a generic activity. With a bit of thought and planning, you can make up you own tooling with items at hand such as threaded rod, washers etc.

Good Luck and Easy Does It.

Bill

Yes, you need to remove the bearing covers, at least at the front because the bearing is more likely to stay on the spindle than in the headstock. Look closely at my photo and you can see I've removed the screws from the bearing cover.

The puller only needs a bit of angle iron or a rather thicker bar, a few M10 screws and nut and length of cheap studding from Wickes or B&Q.

<edit> M8 will do if you're a cheapskate

Edited By Neil Wyatt on 23/12/2015 21:51:12

In case you missed it, the guide linked to is for the Super C3, not the brushed variant...

All I had at the time was M6 threaded rod, so NOT being a cheapskate (despite being a Yorkshireman), I splashed out on some M12 rod.

Sadly, the bearings/spindle were just too tight (my angle iron was bending and I 'd reached the end of my strength), so I resorted to the engineers friend and that got it out OK.

Of course I'm continuing to have adventures. one of the circlips has broken and, of course, I don't have any in my toolbox. Why is it that there's always one tool, part or piece that you don't have?

Circlips on the way from amazon, but won't arrive until Sunday. the fun will resume then!

Iain

Well, it's all back to working.

A few things which I've learned that may benefit any other beginners who have this issue.

By all mean's try harder to get Neil's puller to work. Whilst braying the end of the spindle did eventually get it out, it also damaged the threads, requiring me to mill a bit off the end before the collet nuts would go back on. Simon (SPG Tools) indicated that I should have left a nut on to rebuild the thread after the braying. I think that avoidance would have been the better option.

I did use a puller to get the spindle back on. The mechanics worked better, but I was lucky enough to have a piece of pipe from a typists chair which more or less fitted over the thread end spindle. It would have been better with a nice 60mm washer with a 25mm internal diameter. So clearly, one rule is that you should lathe up some parts to make it easier to fix your lathe before you break it!

Whilst it's all gone back together and runs I have the feeling that the spindle is just a bit harder to turn than before so it may be that I've bent something just a tiny bit. Avoid hammers (as all the posters have said).

The other thing which happened as part of this process was that the motor board blew. I suspect this was due to a loose wire or bit of scurf that fell in whilst it was off.

This site has the circuit for the board which appears to be correct and was very helpful. I replaced one of the diodes and also both SCRs. They were both working but by the time I'd got them out, I thought I might as well stick in some 20A ones instead to give the board a bit of overhead if my new (metal) change gears take the strain and load the motor board.

But it never ends. either during the repair or before, the tailstocks gone well out of alignment and it's a damned trick thing to get set up. But that's tomorrow!

Iain

Correct me if I'm wrong but you did remove the headstock from the lathe bed to do all this?

In which case you need to realign the headstock to the bed and tail stock.....

Good to hear its working tho'

Never use wood to try and drift shafts or bearings free. The wood can splinter and / or leave dust in the bearings which causes other problems later, including ceased shafts. better to use copper or alluminium. Wood also absorbs the impact of whatever you hit it with so wastes energy.

Hi, John.

As far as I can see the headstock is self-aligning. There's an inverted v keyway that runs the length of the bed. the headstock is tightened onto that which positions it.

Having said that I will run an indicator along a test bar first, before messing with the tailstock.

Iain