Hollow, Small-Opening, Interior Finishing

Frank Townend

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Alexandria, Virginia
I've read several discussions on the merits and methods to clean up the interior of hollow turned pieces with a small opening. I've read about sandpaper on forceps, the different Velcro-based sanding systems, inflatable sanders, getting your child's fingers in there, etc.

I was wondering if anyone had used sandblasting media, small stones, shot, or Metal Vibrator/Tumbler Resin Abrasive media inside a slowly spinning hollow piece.

I was thinking I could 1. turn a hollow piece, 2. partially fill it with the media, 3. tape closed the opening, and 4. let it run for a couple of hours on a fairly slow speed.

Has anyone tried this?
What are your thoughts?
 
I read somewhere of someone doing something along those lines. I don't recall any of the details, but I seem to remember them talking about using rock tumbling media. Seems it should work, although on woods that have a lot of variation between hard and soft spots, the "sanding" could end up being uneven. (Although you can run into the same issue when sanding with the other methods, too.)
 
Thanks Vaughn,

I agree about hard and soft areas.

I haven't "advanced" my bowl turning skills yet to move up to hollow forms, but I was thinking the process has the advantages of power and time with the piece left running on the lathe.

Maybe I'll just make hollow forms that are 0.00390625" thick with a 0.0078125" opening. That way no one can see the inside. :)D)
 
I've been thinking about this, and I wonder if it would work. You would have to put a lot of abrasive media into the HF, or it would just go to the lowest spot in the HF and stay there......... I think....... :dunno:

I doubt I can get anything like that over here, in less than 100Kg packs, so I'll have to watch for you guys to give it a go.

Cheers!
 
I remember someone talking about this on a forum somewhere as well. They set up a very low speed motor with a bolt to fasten their chuck to it and used some kind of rock. I think he did run into the high/low because of hard/soft parts of the wood.

Had to look for it and found it....allen neighbors at smc
 
Yes, I Have

Yes. The first turner I knew of that did it was Terry Daniels. I have been meaning to set up such a rig. I think Allen and I saw it at the same gathering in GA. What held me up was getting the motor that turns at she speed needed. I hate to make this kind of thing because I know so little about what to do and where to get what I need.

My lathe is up the road in another building (some use their lathe). I don't even leave it plugged in more less running. I was going to set the motor up in the garage where I could keep an eye on it.

If anyone can tell me exactly what I need and where to get it I would be sooooo happy!:thumb:
 
If anyone can tell me exactly what I need and where to get it I would be sooooo happy!:thumb:

Barbara, I know Allen will give you all the info needed. He has emailed me a few of his "homemade buffing" ideas in the past. He also has pics and an explantaion of his setup posted on the WOW site.
 
Thank you all.

I agree about getting it off the lathe and on to a slow speed motor.

I'm not looking for a mirror finish, just nicer than the dings, dangs, and dodges I expect to get.
 
Hollow forms

:)Here is a hollow form that I'm doing. I used a SorBy round shear scraper to get it cleaned up and I used forecepts for sanding the interior. The opening is 1". :wave:
 

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Beautiful piece John. Do you go through the different grits of sandpaper, or is most of the work done by the Sorby round shear scraper?
43224-01-200.jpg
 
Hollow form

:) The round scrapers does a good job. You just need to go easy so you don't go through the sides. I'' use 180 then to 200 grit on the inside. I've seen other journeyman turners feel the inside of the form to see if it was turned with a professinal touch. Something that a novice like me picked up watching their expressions. You can tell if they approve or not. It only makes the vessel one of good craftmanship and pride for the turner.:wave:
 
I'm probably using faulty logic, but I would think that unless you turned at a very slow pace, the centrifical force would just move the medium out to the walls and it it would just stay there ... kinda like the saw dust does..
 
Terry Daniel made his HF smoother so that it would turn at 30-40 rpm's. He felt that at times that speed was too fast and was going to try another arrangement last I spoke to him about it. His set up used pulley's to reduce the speed. He was thinking about trying a lawn mower transmission to slow down his motor as well. A gear reduction motor would do the job if you can find one that is slow enough. He had a "spindle" the same size as his lathe and would spin on a chuck that would hold the piece securely.

His original medium was the gravel in his driveway. You could look around and see the difference between the stone that had been and had not been used yet. His idea was that the stone should slide and tumble inside the piece and basically beat down the rough areas. Too fast and the stones would be held in place by centrifical force.

Another issue that was dealt with was how to get the whole piece "sanded." His solution was to arrange the whole thing on an angle, about 10-15 degrees, and fill the piece about 2/3 full. The rock would get the entire bottom and up the entire side. Tape was put over the opening to help keep the rock inside.

It hasn't been talked about yet, but the time that Terry allowed the rocks to tumble was a lot longer than I would have thought necessary. Generally he let the tumbler go for a couple of days. He would usually check the progression after about 24 hours and then let it spin for another 24 or so. Seemed to work pretty well for him. Don't know why it wouldn't work for anyone else. I have found only one reason why it won't work, if one doesn't expend the energy and time to build such a tumbler.
 
I'm thinking an automobile side window from a wrecking yard. The way that safety glass breaks up into little squares, I'll bet it would work very quickly and also last a long time.

Now, I've got another project to add to my roundtoit list. :(
 
You could also probably adapt a barbeque rotisserie motor to spin the lathe spindle. (I'm thinking a belt arrangement between the rotisserie motor and the lathe handwheel would work.)
 
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