Articulated sanding arm

Re: Articulated sanding arm

John K Jordan

Reed, I posted this reply on SMC - reposted here for discussion purposes:

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I like the large bearing surface of the pivot on the lower arm, especially since it's made out of wood. Is the problem too much friction, or do you want smoother pivoting? Is so, a thin washer made from HDPE or something might help. Or are you looking for engineering ideas to produce these to sell? Want less play? Something else?

I can imagine that bearings that allow the arm to move too freely could be a hazard to the guy who turned the lathe on then let the arm swing into the work. A positive lock could help with this, saw with the type of locking lever typically used to lock the tool rest in place, tightened from below.

That's a great idea - I need one when using a rotary carver for long stretches. I've been resting my arm on a tool rest which is not ideal. I may make one, probably welded steel.

Do you find yourself adjusting the height often when sanding? If not, a collar locked to the tool post with a set screw could set the height. The sphere jig I have uses this method.

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JKJ

Re: Articulated sanding arm

Dave Paine

Thrust bearings may help if you are looking to get a smoother articulation.

I am using these in an articulated arm for hollowing tools.

Works well. I can tighten the pivot bolts so the arm can articulate, but with no vibration when used.

This design is using the tailstock to mount the arm. I could easily modify for a sanding arm to mount in the banjo.

Send me an email if you want to discuss this. I am happy to help. I love making new one-off projects.

Re: Articulated sanding arm

robo hippy

Dave, those thrust bearings may do the trick. I would think I would need bigger ones..... Hmm, have to ponder that.

robo hippy

Re: Articulated sanding arm *LINK*

Dave Paine

There are many sizes available. You are not putting much of a load on the bearing. From your video it looks like you are just resting your arm and the weight of the drill.

I cannot imagine needing bigger than 3/4in ID.

I can easily machine a post for the banjo and reduce the diameter for the ID of the thrust bearing then thread the end for whatever nut and tpi needed to hold things together.

Another option is to use a needle roller bearing or this and the thrust bearing. Example link below.

Your videos have helped me in the past, so happy to return the favour.


Needle roller bearing example