General Category > General Discussion
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
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