Bad vibrations.

[Les Symonds]

  My lathe is a Coronet Number 1, which I thought, when I bought it, was the bees-knees. Compared with the old Arundel J4 that I had 30 years ago it is big, tough and heavy, but I'm having terrible trouble with vibration. My biggest problem is hollowing out any shape, even small trinket boxes cause problems. I have a 1.5" by0.5" square end scraper and I have to nibble away with the very tip of the corner of the blade....any more metal in contact with wood and the vibrations screech away. The same goes for gouges!

The lathe is bolted down to a bench that I built out of softwood 3"x3" legs with 3"x2" framework, all jointed and glued&screwed together, and the top is made of 2 sheets of 18mm mdf glued and screwed together and down onto the framework.

It just seems to me that there is something seriously wrong, and it's stopping me from advancing any further with my skills as I can't break free from the little bits of wood that I currently turn. my shelves are full of 12" and 14" blanks and I've a mound of wet wood that I'd love to have a go at, but there's no hope of that until I sort things out.

Does anyone have specific knowledge of the Coronet Number 1 lathe? It would be very helpful to know if this is just a generic problem with the lathe, or something specific to my set-up.

Any help/advise gratefully accepted.
Les

[Bryan Milham]

Les,

I'm not saying this is the problem. But my first lathe was the Coronet Major (Woodworking machine).

I got a similar vibration on that and tracked it down to the phosphor bronze headstock bearing. It had worn slightly at the rear (pressure from many years of tools pushing on it I guess).

As I think your lathe has the same bearing arrangement, it may be worthwhile checking it, Is it set properly (no slap) and or it the inner surface still true.

Fixing can be a problem as they are a taper fit. I had an engineering works at my call at the time to sort it out, nowadays I'd have to buy a new one or pay a works to true it.

[Les Symonds]

Hi Bryan...thanks for that info. Whilst I can't really feel any movement in the drive from the headstock, it has to be said that the vibration does not occur when pressure pressure from the tools is being directed towards the tailstock and therefore away from the headstock bearing.

I guess that I'm going to have to find a reputable engineering company somewhere nearby. We have a small engineering works/forge here in Bala and I paid them to make up a pair of toolrests for me. They used a metric round bar, which doesn't fit my saddle, and thehorizontal bar for the toolrest is welded out of square - so I don't think that I'll be using them!

Cheers...Les

[Les Symonds]

Hi again Bryan (and anyone else who might have any useful advise). I examined things a little more closely this evening, and the noise and vibrations are clearly getting worse. I tried mounting an irregular-shaped lump of ash and turning it at the slowest speed, and the bearing was giving a quiet, regular knock. As I trued up the piece and increased the speed, so the knock became louder and faster. Next I slackened off the motor and lifted it a touch to take tension off the belt, and the knocking subsided. When I then slipped the belt off and ran the motor, there was no knocking and the motor ran really smoothly.
Unless anyone can suggest any different, it looks to me like Bryan's feelings are justified, so I'll look into getting the main bearing checked out. What I don't know, is what can be done about a sealed-for-life bearing that's showing signs of wear, can they be removed and replaced, or drilled out and shimmed in some way?

Any further info will be appreciated.

Thanks...Les

[John D Smith]

Hi Les, I used to have a Coronet lathe an it was quite easy to change the sealed for life bearing I am sure you could download instructions from somewhere on the net.The one tip I remember was when removing the pulley when you have taken the first allen grub screw out there is another one underneath so make sure you remove that as well or you will finish us scoring the spindle.another tip is on the side face of the bearing there are a series of letters and numbers that is the part number unique to that bearing.I purchased mine from Seager Bearings if you buy from a lathe manufacturer the are very expensive you may not have a Seager Bearings near to you but I am sure you will find one on the internet.
I hope this may be of some help if you lived nearer to me I would come and do it for you.It's not a difficult job.

                                                 Regards John   

[John D Smith]

Les, Further to my previous message I sold my lathe to a Derek Pyatt he specialises in Coronet lathes and Spares also he is very good with advice.A link to his web site is bellow.Regards John

                                  www.coronetwoodworking.co.uk


  

[Bryan Milham]

Les,

As John says, changing bearing races is not too much of a problem. I did it on my Major but it was a lot of years ago and I cannot remember the procedure I used. I know I managed to locate a 'User's Handbook' which gave an exploded view, which helped greatly.

I'd also say that when buying new races try and get the best quality you can, they might all have the same numbers but I can assure you that there are big quality differences in them and it will come down to cost.

The Phosphor Bronze bearing can be adjusted, have you done that?

Also Record took over and based some of their lathes on the old Coronet range, I think the CL3 has a similar bearing. It may be worth an explore to see if they are interchangeable, should you need a new one.

[Les Symonds]

Hi John and Bryan....thanks so much for the help, the info could well prove to be very useful. I've e-mailed Tony at lathes.co.uk to see if he's got a manual and if he doesn't come up trumps I'll try the other leads.
Thanks again....Les

[woodndesign]

You've isolated it to the headstock and bearings, I consider the pulley in investigations too, it's more likely to clunk, than cause a vibration, but worth a check if loose, happened with my Myford Mystro ... hair loss job finding ..

You'll hopefully get a manual, and it will advise the key way up is when sliding the shaft through the housing and into the pulley so the key doesn't drop out and jam or leave only the grub screw as drive and the key rattling about in there.

Cheers    David

[thebowlerhattedturner]

Hi Les,
          before you get too involved with bearings etc just check that all the nuts and bolts and screws are tight. I know this sounds obvious ,but I once had a similar problem on a different lathe and found I had lost a mounting screw for the motor. There could be nothing worse than changing the bearings only to find it was a screw loose.
Hope you get it fixed.
Regards
John BHT

[Les Symonds]

Hi all....I'm getting there! Armed with the confidence that you lot know what you're talking about, I decided to set about my lathe with a hammer and a brass drift-rod, and was more than a little surprised at just how soon it was in a (well ordered) little pile of pieces.

The most reassuring bit was confirming that it most definitely is the main bearing at fault. Not only does it have a general grumble when it's turned by hand, but also, there is a distinct click on one spot - and that's under no-load and turning at about 60rpm.

I've just contacted Derek Pyatt at Pyatt Woodworking (thanks for the lead, John) and hopefully, he'll have the parts. Whilst the smaller bearing and the poly-vee belt seem to be ok, I'll change the whole lot whilst it's in bits.

My biggest problem at the moment is that whilst the smaller bearing is now off the shaft, the main bearing is reluctant to come off it.

BRYAN....I know next to nothing about bearings, especially what it is that a phosphor bronze bearing looks like, but this main bearing looks just like any other bearing that I recall having handled in the past, and there isn't anything adjustable about it, so I guess that the Major and the Number 1 must have different assemblies.

Meanwhile.....I might just take up knitting for a few days.

Cheers guys....Les

[John D Smith]

Hi Les, I am glad you seem to have got to the bottom of the problem I am not clear about your explanation of the other bearing (main bearing) it seems to me this is another sealed for life roller/ball bearing am I correct and there isn't a phosphor bronze bearing???

                                                                             Regards John 

[Les Symonds]

Hi John....I didn't know what I'd find, but Bryan believed that there would be an adjustable phosphor bronze bearing in there, IF it was the same as the old coronet major. What I found was that both bearings - the main one at the inboard end and the lesser one at the outboard end - appear to be ordinary roller/ball bearing races.....just as I've occasionally seen in a car or trailer wheel bearing.

Les

[Bryan Milham]

Les,

Yep, sounds like I was wrong in my guess as to what you'd find.

As for them looking like the sort of bearing used as wheel bearings - right first time, that's just what Vicmarc use. A wheel bearing from the Holden (an Aussie GM brand) - well spotted.

[Les Symonds]

As for them looking like the sort of bearing used as wheel bearings - right first time, that's just what Vicmarc use. A wheel bearing from the Holden (an Aussie GM brand) - well spotted.

Right-on Bryan....and that Crazy Canadian guy on YouTube who turned a drive shaft and hub of his 4x4 into a lathe obviously knew what he was doing!
http://www.youtube.com/watch?v=P4qB6n1cm04