making new lathe spindle

[Michael GilliganParticipant @michaelgilligan61133]

Graeme,

You have probably already seen the page on lathes.co.uk but I've linked it for ease of reference.

The bearing design is very poor [as was obviously discovered early in the life of this model].

If you want to work it rather than restore it … I would make a solid bush, with a taper bearing, and clamp it solidly in the front "adjustable bearing".

MichaelG.

P.S. Have a look at Neil's Mega Adept thread for inspiration !

[Graeme WhitfieldParticipant @graemewhitfield34761]

I went through the mega adept thread last week, ive browsed the forum quite a bit before i joined.

Ill get the wife to pick me up a copy of the magazine, she goes through town every day.

It is a machine that will be used, but only lightly as i dont often need to turn much. i guess that will change as i get used to having a lathe about though.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Hang on, took a while to click, do you mean convert the front bearing to a taper roller bearing?

Hmmm, i wonder if there is room…

[Jesse Hancock 1Participant @jessehancock1]

What a great little lathe. I'd put it on the coffee table in the front room and use it as a talking point.

It kicks rump on so many levels. You lucky dog.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graeme Whitfield on 23/02/2015 19:11:22:

Hang on, took a while to click, do you mean convert the front bearing to a taper roller bearing?

Hmmm, i wonder if there is room…

.

I really don't know if there is room for a full taper roller assembly, but; if not, you could use just the outer race, and then sleeve the existing spindle with a Bronze male taper …

I think we need some dimensions.

MichaelG.

[Graeme WhitfieldParticipant @graemewhitfield34761]

They are pretty. I was looking for a good one of these for ages. Got lucky with this one really. Not all original but modified over the years by someone who knew what they were doind.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Michael, what dimensions are needed, ill go measure it.

[blowlampParticipant @blowlamp]

Posted by Graeme Whitfield on 23/02/2015 19:11:22:

Hang on, took a while to click, do you mean convert the front bearing to a taper roller bearing?

Hmmm, i wonder if there is room…

I don't think I would personally consider a taper-roller bearing conversion with that design of headstock because there is no bracing between the bearing stanchions to take the necessary preload. I'm pretty sure those supports would close up when loaded and pull them out of alignment.

A new oversize spindle should be doable with a little care as should line-boring the headstock bearings with a between-centres boring bar.

Martin.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graeme Whitfield on 23/02/2015 21:51:21:
Michael, what dimensions are needed, ill go measure it.

.

For starters:

• Diameter and length of the hole in the casting
• Diameter of the spindle on its bearing surface
• A sketch of the existing plain bearing would be useful for reference. [Can you easily remove it from the casting?]

… It looks quite promising.

MichaelG.

[Graeme WhitfieldParticipant @graemewhitfield34761]

There is no bearing in the casting, tje spindle runs in the iron. Its shaped so it looks like a bearing but there isnt.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Good point blowlamp, I could probably rig something up to see how much pressure it takes to start closing that gap. As for boring, id have the headstock apart so couldnt power any cutting tools.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by blowlamp on 23/02/2015 21:59:26:

I don't think I would personally consider a taper-roller bearing conversion with that design of headstock because there is no bracing between the bearing stanchions to take the necessary preload. I'm pretty sure those supports would close up when loaded and pull them out of alignment.

.

Martin [and anyone else interested]

How much preload do you really need on the bearing in a small headstock?

I suspect that even with no preload, the result would be better than the original arrangment.

MichaelG.

.

Edit: I just found this, which is encouraging.

Edited By Michael Gilligan on 23/02/2015 22:23:15

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graeme Whitfield on 23/02/2015 22:06:29:
There is no bearing in the casting, tje spindle runs in the iron. Its shaped so it looks like a bearing but there isnt.

.

Ah … Sorry about that … it's rather deceptive.

Answers to my first two bullets would still be interesting.

MichaelG.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Spindle is 0.996″ but at bearing journal is worn down to 0.993″ housing is 1.156″ wide. The thrust area bit that looks like a bearing sticking out is 1.660″ diameter.

[Graeme WhitfieldParticipant @graemewhitfield34761]

I cant measure much wear in the bore. Trying to measure the bore using digital calipers I get 0.998″. Thats with the adjusting nut slack. Using internal calipers to feel drag I cant detect any difference in bore diameter anywhere.

There must be though as thats only 0.002″ clearance, allow a bit of claming down with the adjuster and that should be well in spec for oil clearance in plain bearing. However, I can easily see/feel lift in chuck and have measured 0.12mm lift with my dti.

(Sorry for switching from imperial to metric)

[Graeme WhitfieldParticipant @graemewhitfield34761]

Ahhh, im an idiot. Journal is worn to 0.993, giving me the play.

So the spindle is worn more than the bore.
Interesting, maybe just finding someone to plate/grind or sleeve the spindle is the way forward?

also means making a new spindle is viable again. Nothing to loose in trying I guess. For a beginner I guess the through bore and taper will be the hard part.

Edited By Graeme Whitfield on 23/02/2015 22:35:11

[Michael GilliganParticipant @michaelgilligan61133]

For reference: Here is a typical 1" bore taper roller bearing.

Outer diameter is too large … although I believe there are also 'slim' versions available for things like motorcyle headtocks, so all may not be lost.

Alternatively, consider my Plan_B instead.

MichaelG.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Ill be honest, I skimmed the link, but seems very little preload needed on taper bearing then.

[Michael GilliganParticipant @michaelgilligan61133]

Graeme,

Our last posts crossed in the æther

If the bore is as good as you think, then please ignore my previous suggestions … it should be quite possible to plate and grind the spindle.

MichaelG.

[Graeme WhitfieldParticipant @graemewhitfield34761]

I looked earlier and normal 1″ imternal are all near 2″ external. I did briefly look at cycle headsets. The tapers in them are tiny and 1″ in a steerer dimension.
Motorcycle ones are standard, I have them in all my motorbikes.

I thought cycle ones might be too light duty though but maybe not if they dont need much preload.

Might be easier all round to just fix this spindle though.

Edited By Graeme Whitfield on 23/02/2015 22:55:12

[blowlampParticipant @blowlamp]

Posted by Michael Gilligan on 23/02/2015 22:10:41:

Posted by blowlamp on 23/02/2015 21:59:26:

I don't think I would personally consider a taper-roller bearing conversion with that design of headstock because there is no bracing between the bearing stanchions to take the necessary preload. I'm pretty sure those supports would close up when loaded and pull them out of alignment.

.

Martin [and anyone else interested]

How much preload do you really need on the bearing in a small headstock?

I suspect that even with no preload, the result would be better than the original arrangment.

MichaelG.

.

Edit: I just found this, which is encouraging.

Edited By Michael Gilligan on 23/02/2015 22:23:15

I don't think it would need a heavy preload, but I do think it's important for the headstock housing to be stable & rigid to resist loading which would now be borne mainly by the front bearing. I just wonder if that design could possibly move far enough under load to allow the rear bearing to 'disconnect' from its race.

Most taper bearing assemblies are within tubular or box shaped housings for rigidity I think.

Martin.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Here is the spindle, its just the larger area that is worn.

Options are, try and make a new one.

Get it ground and plated.

Get it turned down and sleeved.

I have no idea, but my gut feeling is sleeved would be cheaper to get done than plated?

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Graeme Whitfield on 23/02/2015 22:54:24:
Motorcycle ones are standard, I have them in all my motorbikes.

.

This style is usefully a litle smaller.

But re-working the spindle definitely looks like the easy option.

MichaelG.

Edited By Michael Gilligan on 23/02/2015 23:13:53

[Graeme WhitfieldParticipant @graemewhitfield34761]

Cant add a link, but bicycle ones in 40mm internal are only 52mm external and 7mm wide.

[Graeme WhitfieldParticipant @graemewhitfield34761]

Been to see a few pro’s, they all said boring it isnt a good idea. They all said just grind, plate and re grind the spindle. Been quoted ?115-?130 from one company an ive another to go see. No one seems to think sleeving the spindle is a good idea either.

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