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Re: Slack sander

Posted: Sat Jun 18, 2016 8:24 pm
by dwpipes
Yesterday I put the finishing touches on a slack belt sander that I have been putting together over the last week. I have had the pulleys and steel on hand for over two years, but finally had the courage to buy the motor and tackle the project. I am a very marginal welder and the finished product looks pretty ugly, but I think it will hold together. It uses 2" x 72" belts. I set it up with a one half hp, 1725 rpm motor using a 1.5" motor pulley. The belt drive shaft has a series of six pulleys stepped from two to six inch diameter. The belt drive pulley is 3.82" dia., which means it delivers one surface foot per revolution. This gives me a range of belt speeds from 431 surface feet per minute up to 1294 sfpm.

I have one 220 grit belt that I used to set the distance between pulleys. I have used it just a little on 431 and 518 sfpm. I think I could run it faster at 220 grit. It may be my total lack of experience with this mode of sanding, but I suspect that I have the belt tension too high as the belt doesn't seem to want to conform to the shape of my hand. Will have to play with that to see how loose I can set the belt tension and still have good tracking. May also be a lack of confidence and concern about cutting my hand on the edge of the belt. I also ordered more multi-purpose cloth backed aluminum oxide belts so that I can try it with different grits and speeds. Any advice on optimum belt type would be greatly appreciated.

http://www.dwpipes.com/images/SBSander1.jpg
http://www.dwpipes.com/images/SBSander2.jpg
http://www.dwpipes.com/images/SBSander3.jpg
http://www.dwpipes.com/images/SBSander4.jpg

Re: Slack sander

Posted: Sat Jun 18, 2016 8:51 pm
by sandahlpipe
I like your design!

Re: Slack sander

Posted: Sun Jun 19, 2016 12:00 am
by oklahoma red
Well done. Personally I think you might have better luck with a narrower belt.

Re: Slack sander

Posted: Sun Jun 19, 2016 1:04 am
by dwpipes
Charl wrote:Like Pastuch, I also use a 2m one. The supplier I get it from, normally keep a few in stock. Apparently the one I use is being used by knifemakers. Different grits and widths, however, will have to be made up by them especially.
I agree, it is not a necessary tool for pipemaking, but then again it helps a helluva lot with sanding.

Ditto to what Pastuch said.
Adjustable is very important. So is slow and so is a soft thin backing to the belt. You want to be able to "shape" the belt with your backing hand to fit the contour of the part of the pipe that you are busy sanding.
Okay, on previous reads of this thread I was interested in sander design and surface feet per minute issues. Just re-read and focused on these comments about type of belt. So, if it isn't a trade secret, What kind of backing constitutes a 'soft and flexible' backing and if they must be custom ordered, who makes them? Is there a good USA source?

Re: Slack sander

Posted: Sun Jun 19, 2016 1:14 am
by dwpipes
sandahlpipe wrote:I like your design!
Thanks
oklahoma red wrote:Well done. Personally I think you might have better luck with a narrower belt.
At the moment putting my hand behind the 2" belt makes me nervous. Narrow belts scare BJ out of me! My hands are my lively hood and I already need bandages too often!

Re: Slack sander

Posted: Sun Jun 19, 2016 8:29 am
by sandahlpipe
I agree. I wouldn't go narrower than a 2" belt. You don't want those edges digging in. If you're worried about injury, you probably want to decrease your speed. I put a VFD on mine and I set it on super slow speed.

Re: Slack sander

Posted: Sun Jun 19, 2016 5:42 pm
by pipedreamer
That's the right way, I used an old fan motor and it worked!!!

Re: Slack sander

Posted: Sat Jun 25, 2016 2:00 pm
by dwpipes
dwpipes wrote:
Charl wrote:Like Pastuch, I also use a 2m one. The supplier I get it from, normally keep a few in stock. Apparently the one I use is being used by knifemakers. Different grits and widths, however, will have to be made up by them especially.

Ditto to what Pastuch said.
Adjustable is very important. So is slow and so is a soft thin backing to the belt. You want to be able to "shape" the belt with your backing hand to fit the contour of the part of the pipe that you are busy sanding.
Okay, on previous reads of this thread I was interested in sander design and surface feet per minute issues. Just re-read and focused on these comments about type of belt. So, if it isn't a trade secret, What kind of backing constitutes a 'soft and flexible' backing and if they must be custom ordered, who makes them? Is there a good USA source?
This week I received several cloth backed belts of different grits from McMaster-Carr. Most of them were X-weight like the first (220) belt I was using, but the new 240 & 400 grit belts were J-weight, which is lighter and more flexible. I went back to check and M-C does not give the ordering option by backing weight. Apparently they ship whatever they have in stock with no regard to backing weight.

Is cloth backed J-weight the best belt to use or is there another option I need to find?

Re: Slack sander

Posted: Sat Jun 25, 2016 10:41 pm
by baweaverpipes
J weight is my preference.

Re: Slack sander

Posted: Sun Jun 26, 2016 3:06 pm
by LatakiaLover

Re: Slack sander

Posted: Tue Jun 28, 2016 6:58 pm
by dwpipes
baweaverpipes wrote:J weight is my preference.
LatakiaLover wrote:http://www.trugrit.com/#
Thanks for the feedback and link. Truegrit makes a further distinction between j-weight and j-flex. Looks like j-flex is the way to go.

Re: Slack sander

Posted: Wed Jun 29, 2016 3:52 am
by Charl
I don't know about the weight, living out here in Cape Town you use what you can get, but it has to be thin and flexible. The idea is to use one hand at the back of the belt to "mould" the belt to the pipe.

Re: Slack sander

Posted: Thu Jan 26, 2017 3:32 pm
by HLJ3
The Sander I built is similar to Don Warren's as far as belts (2"x72") motor (1725rpm) pulleys 1.5"/6". I made the legs and upright post out of 2x2x1/4 square tubing and the boom is 1 1/2x1 1/2x1/8" tubing and the tension post is 1 1/2" round Stainless tubing. I can adjust belt tension easily, and by pushing down on the boom, belt changes are quick. There are some photos of it in progress and finished product in my photo gallery here: http://imgur.com/a/eH5A3 It started out with a third idler wheel, but I found it unnecessary. I shortened the legs and upright and painted it with Rustoleum Appliance Epoxy. I was going to powdercoat it, but the epoxy is really holding up well and a lot less expensive.

HL

Re: Slack sander

Posted: Thu Jan 26, 2017 7:11 pm
by oklahoma red
Nice rig and nice shop.

Re: Slack sander

Posted: Fri Jan 27, 2017 7:36 pm
by pipeguy
Very nice setup :D I made mine to the specs that Rainer Barbi gave me
No step pullies 1/8 hp motor 2"belt x110"about 200ft per min.

Re: Slack sander

Posted: Fri Jan 27, 2017 9:23 pm
by HLJ3
Mine with the 1.5" motor pulley wheel to 6" pulley has my belt speed right about 446 sfpm. It's plenty slow enough not to cause speed friction problems with my fingers. The belts are nice and supple too. (Econaway Abrasives)

HL