Advice Wanted - On obtaining help...

I hope if put this post in the right place - it seems the most appropriate forum to me.

I need a replacement component made for an old small (12"  lathe. It's a new mandrel with a different nose thread). So it's a small component but includes a small section of screw cutting and internal morse taper, which I am unable to do with the facilities (and expertise) I have.

I'm looking for some advice on whether there is an "accepted" (or recommended) way of finding out if it's the sort of thing someone would be prepared to help with. Or, indeed whether it's a job that's too big (in complexity rather than size terms!) to expect help with.

I'm also going to do a bit of googling to see if I come up with any suitable commercial services that aren't prohibitively expensive but thought it would be worth asking here as well.

Andy

Edited By Andy_H on 13/09/2023 16:33:13

Hi. A little more info would be helpful in getting the correct advise. Make & model of lathe ( a picture speaks a thousand words) A few dimensions. Your approx' location.

As much info as you have make things much easier.

regards

Further to Oldiron's point, by 12" do you mean of 12" centre height or 6" ditto? Neither would be a small lathe in a hobbyist's book.

Or is it 12" between centres?

Ah, I entirely see your point and of course the unintentional ambiguity in my post. Apologies.

So, the lathe (a Flexispeed) is 12" between centres. The part I want to replace (the mandrel) is about 5" long and would be produced from 0.75" diameter steel.

I would, of course, expect to produce a proper drawing. But I think another point I perhaps failed to explain in my original posting was I am not ready with all the precise details yet (I am working on that) but was instead simply trying to gague whether this is it's the sort of thing that would be deemed acceptable to seek help with or, to be put it bluntly, be looked upon as a damned cheek!

Andy

Andy

When completed put a picture of your drawing in your Photo album and perhaps some kind person may be able to help you.

Emgee

I presume by "mandrel" you mean what would normally be called the "Spindle"

Somewhat similar to this link. Spindle

regards

The Flexispeed is a remote ancestor of the Cowells. Bit of a long shot, but the spindle might fit, and Mr Cowells will sell you one.

Yes I do.

In fact I have always referred to it as a spindle but having seen it referred to in several other posts as a mandrel used it here.

Your question got my curiosity working though wondering how the two terms differ which led me to this definition:

a usually tapered or cylindrical axle, spindle, or arbor inserted into a hole in a piece of work to support it during machining

So my take on this is that, although a mandrel can be a spindle, the distinction is that it's something used with a workpiece, whereas I was referring to the machine not a workpiece - so should have used the term spindle!

Andy

A good suggestion thanks.

I've already made the enquiry today and already have an answer. Although both are 0.5" it is not a suitable replacement. Although at the price I'm rather relieved it's not an option!

Andy

A friend of mine is going to make me a mandrel for a Super Adept. Like yours but 3/8 shaft rather than 1/2 inch. I am using a Unimat nose thread, m14 x 1.

Not a big job at all.

I too replaced a Cowell's mandrel many years ago, it cost about £110 back then, probably 20 years ago.

The only reason I am not turning it now is because I don’t have another lathe to do it on.

If you want an imperial thread on it, you could turn a new mandrel between centres on the Cowells and screwcutting it on the Cowell's itself. I don’t know if you can do a metric thread on a Cowell's but a 63-tooth change gear might help. (Approximately half of a 127-tooth gear.

Hi David - perhaps not a big job providing you have the machine to produce it on

The Cowell's spindle is now £195 +VAT. Wow!

On your last point - I don't actually have a Cowell's lathe.... that only came into the thread as a suggested possible replacement for the Flexispeed part.

Andy

I have now produced a preliminary drawing.

I have also found a small company that claims to do small jobs at very competitive prices so I have requested a quote. I will see what comes of that.

Andy

Andy what is wrong with original spinde. Is it beyond repair or is it just the fit between the bearings and the spindle or is this a modification to original.

David

Andy,

With respect, I think you will find that the Flexispeed is made to Imperial dimensions so you should stick with those, apart from your chosen nose thread.

From your drawing, 12.8mm is a bit more than 1/2", so probably 1/2" bearings. 6.3mm is a bit less than 1/4", so probably 1/4" bore - you need to be a lot more precise than that! And what are you going to do about the worm gear?

If you can find someone to do it, best to just let them have the whole machine and tell them what you want, so that they can fit the spindle to the job rather than trying to rely on a drawing.

And it costs what it costs. It may not be difficult for a skilled person, but it will be time-consuming, so don't expect them to do it for beer money.

£200 odd for the Cowells spindle isn't unreasonable, and an accurately made one-off, starting from scratch, will probably be be more than that.

Sorry if this all sounds a bit negative, but I am not sure you are being realistic. As said- what is the actual problem with the existing spindle?

The reason for replacement is just to change the nose thread so as to make it possible to but replacement chuchs.

Andy

There's some valid points here but, in my defence the diagram IS clearly marked as preliminary and not for production purposes. It was provided simply to provide an indication of the size of the piece and key features (to clarify some points raised in an earlier reply). The drawing also proposes what to do about the worm, gear!

As for the "beer money" point. Unfortunately, my post seems to have been misunderstood right from the outset. The purpose of the post was not originally asking for someone to offer to help (although someone has). It was instead seeking advice on how to go about requesting help and, more importantly, whether it this sort of job is considered too complex to expect anyone to help in the first place.

I fully accept the point about imperial measurements. I would do that on a final version of the drawing intended for production.

Andy

I'd be inclined to have the bore a little over 1/4" so you can pass that diameter stock through it. 6.5mm would do and also avois a step where the small end of the taper meets the bore as MT0 is just over 1/4".

You may also want to condider specifying a finish particularly for the bearing surfaces which may be better off ground than turned.

Does the Flexispeed have bearing shells or does the spindle run directly in the Cast iron, if in the iron than again a little over 1/2" could be useful if the bearing surfaces have become worn that would allow them to be fitted to the new oversize spindle.

If the object of the exercise is just to allow fitting of different chucks, then an easier solution might be to make an adaptor, or a few separate backplates. I had a Zyto branded Flexispeed long ago, and I think the nose thread was 1/2" BSF. If so, no problem getting a tap to start you off.

All this thought and planning just to be able to " possible to but replacement chuchs " ?

Have you already got the replacement chucks and presumably other fitting, or will you have to source them?

Is there any room to make an andapter, which you could do yourself on the lathe?

We try to be a helpful forum solving peoples problems that often they don't have?

My guess is that this "project" won't happen, but what do I know? But good luck with it Andy

Pete

Redsetter beat me to it, lol

Edited By Pete White on 18/09/2023 11:50:50