Outboard turning support

[Chris152]

When turning tricky wood, I sometimes get unacceptable vibration on my Sorby RS2 lathe with the large bowl extension attached. I can rig up a stay using wood to support directly under the tool rest, but as soon as I move the banjo the stay falls away and needs repositioning. (The other wooden stay, under the extension, helps a little but not enough - it needs to be right under the tool rest.) Here's the clumsy setup:

And this is what I'm thinking to make/ have made as a more convenient stay, replacing the bit of wood directly under the tool rest in the photos. The lower section would need to be a weighty steel cylinder into which fits a steel rod, locked to the required height using a bolt.

Could this work? It doesn't need to resist movement toward the lathe or laterally on account of the existing bowl turning attachment. If it could work, would it be tricky to make?
Thanks for any thoughts.
C

edit - alternatively, one like this would be ideal.

 

[Simon_M]

At the moment the bed extension is a long/complex L shape that could be better braced (more than just supported).

If the lathe isn't bolted to the floor, try adding a temporary support e.g. 2 x 4 (clamped top/bottom) between the lathe leg T base and the underneath of the bed extension (triangulation) to see if the vibration is controlled.

If the lathe legs are all bolted (or can be) bolted to the floor, try adding a temporary support e.g. 2 x 4 (fixed top/bottom) between the floor (without the rubber mat) and the underneath of the bed extension to see if the vibration is dampened.

 

[Chris152]

Thanks Simon. I've been thinking about what you wrote and figured one solution to the attachment of the large bowl extension could be this:

I rotated the head through 270 degrees from the usual spindle position (so I'd be working to the 'rear' of the lathe) and attached the extension to the bars between the headstock and tailstock attachment bit. That should limit the potential for the bars to flex as per the usual (supported only by the headstock) position?
What's more, whereas with the headstock rotated to about 45/ 50 degrees the banjo alone (no extension) can't reach to much more than 12" diameter bowls, with the headstock rotated right round to about 310 degrees, and the banjo directly on the bars (no large bowl extension), the tool rest can easily reach to 18/ 20" diameter.

I've yet to turn anything in this position but think it might be - or at least be part of - the solution! No need to have posted in the metalwork section, hopefully...

 

[Simon_M]

Better configuration. Is there any vibration or whip in vertical/side-to-side direction in use vs "normal" setup and a test workpiece?

 

[Chris152]

I'm having a few days off from turning, but I'll try in the next couple of days. I'm sure there was some movement as you describe with the previous setup, but it remains to be seen if this has cured it at all. Fingers crossed...

 

[Trevanion]

Ahh just bit the bullet already and get yourself a VB36, there's one on eBay right now for not too much money! :lol:

I have seen those style of extension and banjos snap the casting before (Not on the Sorby lathe but similar) because there is very little support underneath, one really nasty catch too many and you could have a very sore toe from having 25+lbs of iron land on your foot. So you are going down the right path of trying to get it more sturdy.

I imagine something like the old independent Wadkin tool rests that came with their lathes would be the ideal scenario for replacing the extension and banjo.

 

[Chris152]

I imagine something like the old independent Wadkin tool rests that came with their lathes would be the ideal scenario for replacing the extension and banjo.

I'd seen the VB and even got in touch with the seller Trevanion, but decided to give it a miss! I do like the support structure, though. I've not used the independent kind of support like the Wadkin, but can imagine they're not as solid as they look in relation to pressure toward the workpiece, even with that lump of cast iron at the foot - vertically I'm sure they're fine. But I really don't know, and after market ones of that size are really expensive.

Simon - to answer yours, I think there is more rotational vibration with the extension fitted than with the banjo direct to the bars. I was adjusting today and what I find is that if the banjo's in the 'wrong' place on the extension it vibrates; a slight adjustment (maybe 10mm) toward the extension (with the tool rest ending just to the right of centre of the bowl) and the vibration stops. It seems to be about how the banjo's balanced on the extension.

I think the support I drew up might well be the way to go, just need to get myself together to try making it...