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Jeff
26th March 2002, 02:26 PM
I'm designing a new toolrest for my lathe for outboard turnings. My plan is to use two standard toolrest clamps placed at either end of the lathe bed with the powerhead turned ouboard at the center. I'll come out from the toolrest clamps with arms at 90 degrees to the ways, and bridge between these arms. My new toolrest clamp will ride back and forth on the bridge. If anyone has seen or experienced such a setup I'm eager to hear your comments.

Tim the Timber Turner
30th March 2002, 01:30 PM
Jeff
Your idea sounds OK in theory but would suffer from the same problem all bolt on outboard toolrests suffer from. The problem is that every reaction that happens at the cutting edge of the tool gets transfered to the toolrest, down the toolrest post, into the toolrest holder and into the bed of the lathe or the outboard toolrest attachment as the case may be.

This is why heavy cast bed or heavy timber bed lathes are smother to operate.

In effect what happens is that you get bounce and flex into the bed or outboard setup. The bigger the digin the more flex and bounce, the more flex and bounce the bigger the digin, if you get what I mean.

The best outboard setups I have used all transfer thia flex and bounce straight down the toolpost and into the floor.

Check out the Vicmark outboard attachment and you will see what I mean. It costs $400 plus but could be fitted to almost any lathe.
It's the best off the shelf setup avaliable.

If you decide to go ahead with your idea, cut a piece of 75x75 hardwood about 2 mm oversize and wedge it between the floor and the bottom of the tool rest, the base of the toolpost would be better but means reseting it each time you move the toolrest. For this to work the lathe needs to be bolted to the floor but I suspect that if you turn the head 90 degrees you will have to do this anyway due to the forces generated. The main reason to go outboard is to turn bigger diameters and bigger means more vibration. Given enough vibration the lathe will start to go walkabout. You can't beat a variable speed lathe in this situation. I used a lump of 75x75 for years on my first Woodfast.

Good luck and remember turning hard timber and burls as we have in Australia, ain't no fun with a bouncy toolrest

Tim the Timber Turner

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Jeff
4th April 2002, 06:55 PM
Thanks Tim the Timber Turner...
I've been doing outboard turning for a while now, and have experienced the points you mentioned. I've been using a system with a post that is tied back to the lathe bed with an adjustable arm. I've found this to work quite well for stability, but limited in access to the wood. My new design will allow me to get the toolrest in better position, and will include at least one post as you suggest. Thanks again! Jeff