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I'm trying to thickness a highly figured set of koa sides with my Performax 10-20, and I'm getting burn with slow and fast conveyor speeds. Do any of you have tips?

I'm taking a forced break from it now after my conveyor belt broke. Probably a good thing. I'll have a go at it with a hand plane in a bit.


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On my 10-20 that usually means I'm trying to take of too much. I generally turn the depth-setting crank on top of the gantry only 1/8 to 1/4 turn for each pass and keep the conveyor at fastest speed.

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Steve Smith
"Music is what feelings sound like"

Thanks, Steve. I'm only turning an eighth of a turn at most.

I remember years ago that Hesh was having a similar issue, but I couldn't find the thread.


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Too fine a grit........???
Tom

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A person who has never made a mistake has never made anything!!!

I have similar problems with mesquite. I typically use 36 or 60 grit for very hard/dense woods until very near desired thickness. Also, I run them through at 15-20 degree angle (on 16/32), but obviously you wouldn't want do do that for finishing passes.


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I've found this to happen with maple as well. I found that running the conveyor at top speed and taking very, very light passes makes it turn out ok. Light like .001-.002 light. Takes forever but gets it done...

I was going to suggest running it through at a diagonal, for some reason it really helps, but I am not sure you can on the 10-20. I do agree with the light passes I think an 1/8th every pass is too much. Adjust then run it through a few times adjust again. It does not sand all the way with one pass. If you adjust every pass you might be getting ahead of the papers ability to remove the wood.

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http://www.Harvestmoonguitars.com

80 grit Zirconia, we get ours from Klingspor -- the grit is really sharp and stays that way for a long time. We make no effort to do finish sanding with our drum sanders -- after all they are "thickness sanders." 120g on a Random Orbit for preliminary smoothing.

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Ken Cierp

http://www.kennethmichaelguitars.com/

What grit are you using? What kind of dust collection? I've found that a large amount of airflow via a good size dust collector does a great job at keeping things cool.

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sweat the small stuff.

Grit was my next thought as well. I use only 80 grit on my 10-20. I have no problem with Koa. Maybe there is something going on mechanically?

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Steve Smith
"Music is what feelings sound like"

Thanks for all the input, guys. I run 100 grit. I'll order a pack of 80, and I'll take multiple passes before adjusting the drum.

Do any of you ever have issues with the paper snapping apart when you turn on the drum? I lost two brand new rolls to it today.

I've never had that problem. I've had it drag on the inboard side when I get down to around 0.050" (or in that neighborhood) but not had it actually snap apart.

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Steve Smith
"Music is what feelings sound like"

I had some light browning/burning with my 10-20 when trying to thin figured maple with 80 grit Performax Paper.

I need to order some of the Aluminum Zirconia 80 Grit that Ken mentioned ( http://www.woodworkingshop.com/product/pe40280/#.VXYH81xViko ), but here is how I made it work:

I did super light passes with 36 grit, feed on high speed. It seemed at lower speeds I'd get more heat build up. 2-3 passes between each thickness adjustment. I ran the pieces as much on the diagonal as I could. With these being long sides is was only a slight angle but helped. With three passes I'd to a >90 degree, <90 degree and then straight through.

I then only did some last finishing passes with the 80 grit - multiple passes at angles and straight through without adjusting the drum. Finished up with 120, 180 and 220 with the random orbital.

That's 1/8th of a turn, not inch. I can't remember what the thread pitch is, but that isn't much.

1/4 turn is supposed to be 1/64", or .015".

It's an interesting conundrum that I haven't had with any other woods. I've put rosewoods, tiger myrtle, mahoganies, and the usual crop of soft top woods through it without issue, but this koa is really taking the heat.

I ordered some 80 grit paper and a new conveyor belt, so we'll see how it goes. I'm going to have a go at it with my #5 1/2 tomorrow, but I'm concerned about the blade angle being too shallow for the figure. Thankfully the sides are pretty thick, so I won't have any permanent issues if I get tear out.

I don't run a 10 20......have a Grizzly, but the only time I have had trouble with burning I found that my paper was too loose on the drum. I tightened it properly and have had no problem since. Don't know if that could be your situation, but it was my solution.

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Blue Ring Acoustics
blueringacoustics.ca

This one was thicknessed using only hand planes, but high angle (minimum 60 degrees). Try working across the grain to remove the bulk if you only have a standard angle plane, then finish up in line when you get your 10-20 back together.

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

http://www.goreguitars.com.au

Klingspor blue, 80 grit, fast, light, diagonal passes to keep drum contact point cool. Even a 10/20 can do some diagonal. For me, things got way better when I started using that blue paper. You could even go coarser. Just remember you will have to go to a finer grit before final thickness

Sorry bad typing on my part, I get that you meant a 1/8th of a turn. I think a 1/4 turn is .3 mm. My point is that if you advance an 1/8 of a turn per pass you can out run the paper ability to sand. The paper may not be able to sand the 1/8th turn of depth in a single pass. So after several passes you may be trying to sand too much. For any on the hardwoods I advance an 1/8th turn and run multiple passes before I advance again.

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http://www.Harvestmoonguitars.com

Agreed. I usually run it through every which way until it doesn't take any more material off, but I also prefer coarse grit. It just seems to work better.

Regarding the paper being loose around the drum, I get it as taught as I can to leave as little slack for the springs as possible. I also crease it to minimize the the bulge where it feeds through. There is usually just a bit left. What do you guys like to do?

I also like to angle material as much as I can to spread the work out.

Great thread, guys! Thanks for so much solid feedback.

You know, another thought is to use an elevated bed. I have several boards (flattened) with sandpaper on them. Maybe .5" to .7" thick. I don't like getting the drum super close to the conveyor. It may help with heat transfer. I don't know for sure. But I haven't had burn problems in a long time. I think with time you will develop a touch and technique where burning won't be an issue.

That's the thing! In the seven years I've had it, burning has never been an issue!

I'm using double sides for the first time, so I'm sanding the sides quite a bit thinner than I'm used to. I got my rosewood down to .055 without any problems, but I really don't want to take chances with the koa considering how scarce and expensive it's become. The backing board might be a great idea.

+1 on 80 grit, although, I'm lazy all the time and more often than not leave the Klingspor 120 on my 16/32. Key for me is extremely good dust collection, clean paper, dust collection, 1/8 turns run through twice each side diagonally, dust collection, thickness from both sides, and the bottom line is good dust collection.

Of course, starting with a nice resaw at about .110 to .100 for sides, and <.125 for plates means little time under the sander.

I just read two points that caught my eye. First is dust collection, my sander has about a 6 ft run to an Oneida system so dust collection is about as good as it gets. If you are clogging with sanding dust that might cause it to heat up.

Second is it sounds like you are working at around 0.050" which, IME, is where the sandpaper can start contacting the conveyor. Don't know how your height is set but I keep the inboard side about 0.005" lower than the outboard side. This makes sure I don't dig a groove in the middle of tops or backs. If you are set up the same then clearance on the inboard side may be too tight and you may be sanding the conveyor belt which could lead to heat and belt or sandpaper damage. Where is your sandpaper breaking at?

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Steve Smith
"Music is what feelings sound like"