Advice for an occasional turner.......

[Argus]

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A bit of help and advice needed for an occasional turner.

I’ve got a 25 year old Coronet No 3 which has an annoying tendency to vibrate when turning relatively short narrow stuff between centres.

Currently I’m trying to turn some spindle about 9” long and 3/8” diameter and they are coming out with radiating flats along the length.

Any suggestions about a fix for this problem?


Thanks in advance.






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[CHJ]

Headstock front bearing?
Check that the front bearing is adjusted correctly and that there is no play, (wooden batten between bed and spindle/chuck and see if there is vertical movement.
Make sure front bearing is lubricated.

Next check rear bearing for excessive noise or play.

 

[Argus]

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Thanks, Chas and check to all the above.

I think that I'll drag it apart tomorrow and get the bearings out for a look-see. These conical bearings are supposed to be fool-proof, but it's either dead tight or like a dick in a shirt sleeve. ... nothing in between.

Are spare bearings/parts still available, do you know?


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[CHJ]

I believe they are, no doubt that someone who has done likewise recently will pop their head over the fence shortly with info.

 

[Spindle]

Hi

Are you sure it's the lathe causing the vibration and not the work deforming? 3/8 over 9" is quite flexible.

Try:

Taking very fine cuts
Supporting the work from behind with your non tool holding hand
Reversing the direction of cut.

As far as adjusting conical bearings goes - try to do it in the smalllest of increments.

Regards Mick

 

[Paul Hannaby]

I would say a 9" x 3/8" spindle is quite likely to flex and cause the problem you describe and Mick is on the right track.
I would add to his suggestions - make sure your tool is razor sharp and if you are still having problems, try turning a section of an inch or two at a time down to your final diameter, working from the tailstock back to the headstock. This will maximise the support for the section you are turning and using this method you can turn some incredibly thin spindles.

If you want to eliminate the bearing issue, try turning a much thicker spindle. If that isn't affected, you can pretty much rule out the bearings as the cause.

 

[Argus]

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Yet again, thanks to all.

Yes, there is a tendency to vibrate even on larger diameters, so I’m inclining to the bearing issue.

Hopefully I can see what the problem is when I get it in bits.


Again, thanks.


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[wasbit]

Putting too much pressure on with the tailstock could also account for those symptoms.

Coronet spares available from Derek Pyatt at Pyatt Woodworking
- http://www.coronetwoodworking.co.uk/index.html

I also have a Coronet Major/Minor manuual - "Assembly Instructions for Basic Machines & Attachments" if it's of any interest.

HTH
Regards
wasbit

 

[paulm]

Assuming your tools are nice and sharp, not too much pressure from the tailstock, and not pushing too hard with the tools, then bearing adjustment is the next thing to look at.

If you find the bearing goes from very tight to very loose then as someone else said you need to make smaller adjustments and/or make sure you are adjusting the components in the right sequence.

It's a few years since I got rid of my CL4 but if I remember correctly you loosen off the ring on the front outside of the headstock a turn or so, then you adjust the inside ring (inside the headstock) until just nipped up and you can't rotate the chuck by hand, then back it off (very small amounts) until the chuck can just be rotated by hand, then tighten up the outside ring to lock it all in place, test it can still be rotated by hand again and off you go. A little oil dripped in the oiler spout (two or three drops) before adjusting will help also, and regularly in use after that.

It's possible I guess that the bearing has been worn beyond further adjustment or out of true if neglected over the years, but just wanted to make sure you have tried all the usual things before you set about dismantling it. Apologies if grannies and eggs etc

Cheers, Paul

 

[jumps]

I think my No 3 is even older.....
From your description I don't think it's inherently the lathe - otoh 5kg of unbalanced blank causing the bars to flex is

Assuming the bearings are correct, your check list will include -
1. the headstock is accurately alligned with the tailstock (i'm constantly revolving the former so spend a lot of time resetting for spindle work
2. your tail centre is spinning true if live
3. the headstock centre is spinning true - if using a centre in the 1mt it's pretty simple to check bearings and centre by loading up your tailstock csntre and running the lathe against a dial guage or equivilent. then repeat with drive centre and any difference will reflect the centre itself.
4. tailstock tension - this is where I love stebcentres somewhere in the set up. As said any load will cause your issue.
5. As said flex in the workpiece - if the impact of the issue you are seeing is at it's max in the centre of the piece this is probably a factor.

If you need the bearing set up it's identical to the CL3 and the manual can be downloaded from the Record Power site - equally the bearing is the same but there are a number of sources, and recent threads reference them.

 

[Argus]

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Again, thanks to all for the suggestions and I shall work through the options systematically.
I'm glad that spares can be got if all else fails, though I probably won't be when I see the cost!

I lost the manual years ago, but acquired a CL3 manual from an Ausie turners site, so thanks to our cousins down under. This manual is identical to the old and just has the CE marking stuff to bring it up to date.

This No: 3 is vintage 1986 or 7 bought from Axminster when their very little shop was like Aladdin’s cave! It's done a lot of agricultural work in the past, newel posts and the like, before a lengthy lay-up and I'll confess that it hasn't had much TLC.

I had just done a few days tuition with Oliver Plant in Honiton in those days and got hooked on it.
Does anyone remember him? Great bloke, very knowledgeable.


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[Spindle]

Hi

To check for play in the headstock bearing without stripping the lathe why not screw on a face plate and attach to that a length of stock, say 12". Now gently apply pressure to the stock along the direction of the lathe bed, (both ways), repeatedly and see if you can determine play in the bearing. If you place a finger so as it touches the spindle and a fixed part of the headstock assembly you will feel any play. Repeat for various positions over 180 degrees of rotation.
If you observe play that is fairly uniform over 180 degrees all you should need to do is adjust the bearing.
If you observe play differing significantly over the 180 degrees this indicates that the bearing has uneven wear and will need to be trued or replaced.

When you experience vibration on larger diameters do the results resemble barley twists?

Regards Mick

 

[Argus]

Hi


When you experience vibration on larger diameters do the results resemble barley twists?

Regards Mick

Yes Mick - got it in one.


I'll try rhe uneven wear trick, that one I haven't ckecked yet.



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[thomvic]

Lots of good advice there. Another possibility is too much pressure from the tail stock - back off a touch after initial tightening.

The bearings are not expensive - remove the old one and find the reference number then use one of the many bearing suppliers on the net.

 

[Spindle]

Hi

I'm getting a bit out of my depth now, I don't think 'barley twists' are the result of worn bearings - more poor technique. (that's me).
Please try sharp tools, light pressure and support.

I have a CL3, converted to variable speed - I love it - ooh err!

Mick