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cboy 12-11-2007 08:10 AM

Tuning up sanding boards
In a number of threads mention has been made of "tuning up" your sanding boards --- that is, making them perfectly flat. Unfortunately, there isn't much on the site about HOW to do the tuning. I'm hoping some of the experts can walk us through doing this on "non adjustable" boards (boards without adjusting rods such as regular dura block boards). If a board is not true, how do we identify that and how do we get it true? (Posts with pics greatly appreciated.)

kruzr 12-11-2007 02:14 PM

Thats a good point cboy, I'm looking for ideas too .Those air file boards,that sponge pad takes a beating,will wait for expert more responses. :thumbup:

baddbob 12-11-2007 07:57 PM

Find yourself a large flat stable surface that you can attach some 80 grit PSA paper on, then simply run the block/board over the sandpaper. I have a large piece of alluminum plate and also a glass tabletop that works well. You can use anything flat and stable.

Also keep in mind, some of the best blocks and boards can be made yourself with wood, or alluminum, or plastic, etc... Example: many of my color sanding blocks and sticks are made out of 1/4" and 3/8" plexiglass.

Also remember to slightly round off the edges and corners-this helps you avoid any digging action if you slip up on a stroke.

Your work will only be as straight as what it was sanded with, and it's truly amazing how perfect you can make something when you get into the finer grits on a straight flat block, each step down in grit uncovers smaller imperfections not seen during the last stage of sanding and this process goes all the way down to colorsanding before buffing.

Watch those boards with wooden handles-the wood absorbs moisture/shrinks/swells and will warp with age. Also watch any boards with vinyl padding-when the adhesive on the vinyl starts coming loose it'll curl and collect sanding debris between the alluminum and pad which makes an uneven surface. Rubber blocks shrink and warp. Plastic boards like the 3M yellow and hustchins white will shrink and warp. Alluminum boards often get dropped on the corners and deform or the screws holding the handles back out. Bottom line is pay attention and it'll pay off.

Working in the shops I always heard technicians complain about how this block doesn't work well, or I can't make anything straight with this board, and this one works better than any.... problem is they weren't smart enough to figure out why. Ramble, ramble, Bob

Bee4Me 12-11-2007 08:27 PM

Bob's pretty much said it all.
I use a framed piece of 1/4" glass.A door off an old cabinet that I found someplace thats like 3' long and have 3 strips of roll sanding board paper on.
When you true up the Durablocks on the 80,you'll SEE instantly where the high spots are cause they will turn a dark black and be rougher than the rest.
Apply enough pressure to make the board go and cut with steady,even strokes. The "idea" is to let the board cut itself down with as little downforce as necessary cause if you go pushing too hard on the rubber,it will distort it and ruin the process. Wood can take more pressure but you can still distort it as well. I've even taken my wood long boad and used it on top of the Durablocks as a helper to keep things true.

Bee4Me 12-11-2007 09:43 PM

Here ya go.
My glass with paper on a nice steel table. L-R 320,180,80

Using my Durablock teardrop block,This is the inital look.

A minuite or 2 of work.You'll notice the dark areas where it's high.

Another couple of minuits and it's looking good.

After about 5 min on the 80gt and it's "true".

cboy 12-11-2007 10:14 PM

Exactly what I was looking for guys. Very helpful posts. This is really something quite simple to do...but I don't recall it every being explained or demonstrated here on the site. Might just improve a lot of hobbyist's body work. I'm sure it's going to improve mine.

MARTINSR 12-11-2007 10:53 PM

Very good stuff guys. :thumbup:


jcclark 12-12-2007 05:10 AM

I use the surface of my tablesaw for a flat surface.
Great article guys, Jon should save this somewhere.

Bee4Me 12-12-2007 06:57 AM

One other thing I was going to edit is to swap "ends" ,turn the block 180*,and sand after each check, This keeps the block from being "worked" too much on one end from too much pressure or it rocking if it's very bad.

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