Thread: Sanding green turned objects- what are the options?

Originally Posted by KBs PensNmore

Hi Tea Lady,
I have a sanding mop made from strips of clothbacked sand paper with a bolt to hold it all together. If your bowl is not to deep you may be able to use this to sand the inside and ouside, I have used this on several other items to sand and buff "fur" off.
Kryn

Did you home make this? If so I think we need pics. No matter how humble you thionk it looks.

My specialty. You can sand them while wet, but you need lubrication, either oil or water, and it is a mess. I prefer to let them dry, warp and sand. Choices here are either use the spindle lock, sand in one position, then move, or have a 3 phase converter that is programmed so that the lowest speed it goes is in the 10 to 15 rpm range. Any faster than about 25 to 30, and you can not keep your abrasives on the wood.

Most of the 3 phase converters are programmed to turn off at 50 rpm. My first VS lathe was a PM3520A which would go all the way down. When they up graded to the B model, they switched the off range to 50 rpm. I asked them why and was told that if you have speeds that low, your motor will over heat and you will fry your electronics. I told them that I had sanded out thousands of bowls at those speeds, and never had any problems. They informed me that it was not possible. They could program the lathe to run that slow, but I would have to ship the headstock to them, and they would void my warranty. I now have a Robust, and had the owner (Brent English) walk me through the steps to reprogram the converter so the speed goes to almost 0 before turning off. Works fine. I do check the motor housing for temperature, and it runs much cooler when I sand than it does when I turn. Main reason is there is no load on the motor.

If you have a flex shaft type of sander, it is light enough so that you can hold it in one hand, and spin the bowl by hand with the sander using your hand as a brake, or just use that hand to advance the bowl. I use an angle drill and some times use the drill to rotate the bowl for rough spots. It does wear out your arm if you have to do it a lot. Some one needs to invent an articulated arm to support the sander so we don't have to hold them.

robo hippy

Robo,

why do you need to use a lubricant if you sand them while wood is still a bit wet? I am a bit lost here, as the few I have tried, I turned, let them 'dry' for between a few hours and a week (with newspaper or brown paper bags wrapped around them) and then sanded dry while still on the lathe. They seem to be OK so far but I know I am missing something.......

cheers

Mick

PS: I need to work out how to include the original text in my reply!

If you turn really thin, in the 1/8 inch or less, they will dry enough to sand out fairly quickly, in an hour or three, and generally don't load up the abrasives too much. I turn mine to 1/4 to maybe 1/2 inch. If I am turning fresh sloppy wet wood, and try to sand a finish turned bowl, it clogs up the abrasives some thing fierce. The lubrication helps keep the abrasives from loading up as much. The rubber eraser sticks (disc cleaners) can easily remove most build up.

I have found dry wood to be much less fuss and bother to sand out.

Efficiency is intelligent laziness!

robo hippy

Originally Posted by mick59wests

PS: I need to work out how to include the original text in my reply!

Mick, use the Quote button instead of the Post reply buttton.

You then have the previous post that you can edit to only leave the necessary part that you want to talk about.


Peter.

Will try a few things on the weekend.

Originally Posted by robo hippy

If you turn really thin, in the 1/8 inch or less, they will dry enough to sand out fairly quickly, in an hour or three, and generally don't load up the abrasives too much. I turn mine to 1/4 to maybe 1/2 inch. If I am turning fresh sloppy wet wood, and try to sand a finish turned bowl, it clogs up the abrasives some thing fierce. The lubrication helps keep the abrasives from loading up as much. The rubber eraser sticks (disc cleaners) can easily remove most build up.

I have found dry wood to be much less fuss and bother to sand out.

Efficiency is intelligent laziness!

robo hippy

Much appreciated. The stuff I have done has not been freshly cut (but still fairly wet) and I have left them for a little while between turning and sanding so that is why I have not had the clogging issue.
cheers
Mick

What Robo Hippy said... +

If your lathe does not go slow enough, turn it off and let the power sander rotate the piece (the reverse of an inertia sander).

Control the speed of rotation by varying the abrasive pressure against the piece. You get more momentum at the rim and less as you move towards the bottom. The trick is to not get too much momentum at the rim which causes the abrasive to skip the end grain areas (on the inside, where it is needed most) and then to have sufficient to keep the piece rotating as you reach the bottom. With a little practice you can use the momentum created at the rim to complete a pass down through the bottom before the piece stops rotating.

The speed of rotation can also be reduced by changing the belt setting to increase the drag that is created with the rotation of the unpowered motor.

It's an extra fuss, but turning green to final thickness has its rewards in some lovely relaxed profiles, e.g. just finished a batch of the following last week.

Attachment 203318

Lovely piece there Neil.

+1 to completing the finishing while green and on the lathe. I power sand and to hell with the expense of clogged discs. (But if you do a lot of this, get stearate treated open-coat abrasives). Then slop on some nitro-cellulose sanding sealer, knock it back with 0000 steel wool, apply paste wax and buff.

That finish will dull somewhat as the piece finishes drying off the lathe but another coat of wax and a buff by hand will boost the lustre.

I do sand when green. Its just that this piece needs another go.

Robo Hippy: Some one needs to invent an articulated arm to support the sander so we don't have to hold them.

Assembly lines have motorized screw and nut drivers counterbalanced with counter weights or clock spring devices so the tool has no apparent weight when held at the working position.

You could make one with a length of strong cord (550 parachute riser cord), two pulleys and a counterweight.

See center one here: http://www.schneider-company.com/images/weber/img04.png

Originally Posted by tea lady

So I had a lovely time green turning some bowls. I love them going oval as they dry. So now they are dry and no longer round what do i do to finish them? Hand sanding? Jim Carrol has these scotchbrite radial bristle discs. Anyone used them? What do other people do?

Update - After rubbishing these discs last week I actually found a use for them today - and didn't they save me some work . I've been carving some small legs for a bowly thing from Gidgee - initial shaping with the Foredom and a rotary rasp followed by the mini drum sander to remove the rasp marks. From here I usually hand sand through the grits from 320 to 1000 but today I only got as far as the 400 and decided to pull out the radial discs (the yellow grade) and see if they had any effect - - removed the last of the scratch marks and left a finish that hardly needed finishing - cool!. Anything that saves hand sanding those fiddly little bits has to be good