Official Luthiers Forum!

Hey all,

I have a new Jet 10 20 Plus which I purchased after hearing a number of recommendations here on the forum. It appears to be a very well made machine. However, I can't seem to get it to sand stock flat. I have the 80 grit on it now that came with it, I have leveled the drum in relation to the conveyor, and adjusted the tension of the conveyor a number of times. I put a back panel 8" wide and measuring .113 thru it with a bunch of pencil marks all over it for reference. After about 4 passes with about an eighth of a turn between each pass, the pencil marks are all gone. If I look across the panel, it has a noticeable dome in the middle. My micrometer says that the edges went down to .101 or so, and the middle is about .108. Surely this thing will do a better job than this? Can somebody who has used one of these offer me some advice? I must be doing something wrong.

Thanks in advance,

Chris.

If you run it through again twice without changing the setting it will even things out.
The pressure from sanding tends to lit the end of the drum so running it through with very little to cut helps.

Here is a technique that if done correctly will have your machine sanding flat.

viewtopic.php?f=10117&t=25090

BTW, are you a Club Cobra member? I have the engine spread all over my house! (428 FE)

Mike

Chris, I have one of these and it works perfectly, both sanding and tracking.

One thought is you have to make sure that the paper on the end of the drum is not overlapped. It can shift during use if not tight and where there are overlaps of the sandpaper it will cause the wood to be thinner there.

_________________
"Building guitars looks hard, but it's actually much harder than it looks." Tom Buck

Thanks guys,

The paper isn't overlapped, although I suppose it could be too loose. I'll check that tomorrow. The tensioner for the paper is a little fiddly. Any hints for getting things tight? The directions in the manual are less than perfect. Or I'm obtuse.

I tried putting the work thru about 10 times after my initial post without changing the depth of cut and it's still off, .099 at the edges and .105 in the middle. This is over a span of about 8 inches.

Mike, I am on Club Cobra, although I spend more time on the FFR forum, since my car is a FFR. An FE huh? Cool, your car should be a monster. What make do you have?

Chris.

Chris, believe it or not, if you cut your own paper, u can do it backwards, though I doubt that is your problem since u have a new machine. Try the leveling technique above. Do not attempt more than a third turn on the wheel. I set my belt speed at 60 most of the time. Also, take several passes at each setting, turning and flipping the piece. Practice before sending something expensive thru!!

I'm the trouble maker on the Lounge. I want a Unique, hope to trade a number of Harps for the body!

Chris, watch that crazy video in the lounge, the one Ron & Jamo have stickied. U should be able to figure out who I am.

Check your conveyor belt backing plate for flatness with a straightedge, or by sighting along it from the end with the bare drum lower just almost to touch it, with a strong light behind. Shows up any basic problems quickly.
On my 10-20 the plate below the conveyor belt was dished slightly, resulting in thin workpieces sinking slightly in the middle under pressure from the drum as they were sanded, hence thick middle and thin edges.
I solved this (following general advice found on this forum) by using a backing board to support the wood being thicknessed - 24" of 3/4" birch ply 10" wide with 120 grit sandpaper glued to top of it.
I didn't relish the idea of trying to make the plate perfectly flat!

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Colin, I had had the thought that the problem might be the backing plate not being flat. I'll check that today.

Chris.

Chris,
took me a couple of weeks to find it/sort it. I noticed several people recommended using a backing board in set-up posts for drum sanders.
Regarding the tensioner, I found it easier to use my fingers to open the catch/gripper thing/tensioner with one hand and push in the tail of the loading with the other rather than using the tool supplied.
Fit one end (I find left its better), wrap the loading round the drum (I find a small space (1-2mm) between wraps is normal), kind of even it out and smooth it down.
At the other end, bend the loading where it passes through the "slot" at about a right angle (not too sharply, don't crack it) just short (1-2mm) of where it will end up. Push tail into tensioner mechanism, release other hand to grip with tensioner.
Run drum, then stop, UNPLUG, try to take up any slack again, repeat if necessary) .
Hope that makes sense.
I took four/five loadings before I got reasonable first time.
Colin
PS you got "my" (fave, drool) car in your Avatar! - Guitar looks really nice too! Shame they don't have a 'drool' smilie.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

You know you just made me waste an hour drooling - on the FFR forum.....

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It's this new idea from recent decades that everyone gets a participation award. - MUX

Thanks again, everybody.

For those interested, the entire FFR experience is wonderful, and the car/engineering is top drawer. I highly recommend them to anybody interested in building a Cobra.

Chris.

Absolutely brilliant! Thanks for sharing the link.

I'm in love with the Type 65. Just need an extra $30K or so

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Steve Smith
"Music is what feelings sound like"

Steve, I like the coupe as well. Can't afford two though, plus I have nowhere to put the Cobra if I wanted to build the coupe. Guitars are smaller.

Chris.