Finger/Box Joint Software

[dlcw]

Bob and all, How accurate are the drum sanders for thickness? Currently making two products out of 3-4 boards at a time that fill table surface of the Desktop and surfacing at 4IPS as they are all different by .002-.004" and some of the cuts are only .025 deep. Can't have cribbage board lines and countersinks disappearing on me like they do when I don't surface Balking at the price tag if it won't get me close to dead nut thickness.

Scott,

Every piece of solid wood that goes on my CNC goes through the drum sander first. I have a Performax 22-44 that I've had for years. Mine is aligned for two pass operations meaning the end furthest from the motor is about .005 higher then the end closest to the motors. This enables the operator to run a board up to 44" wide though and then turn it end for end and hit the other side. You can also align the machine for one pass operations meaning both sides of the drum are exactly the same height.

If aligned properly they are extremely accurate. Never had a problem with any projects I've done using it to flatten my stock after jointing and planning it. I use a micrometer for checking thickness as I work. I leave a very small amount of extra wood thickness for ROS'ing to get a really smooth board.

I am getting ready to sell my Performax sander and go to one that has a drum head as well as a flap sander head so I can use it for finish sanding. A normal drum sander leaves noticeable sanding marks. Jet makes a sander (adapted from their purchase of Performax) that oscillates back and forth as it sands, supposedly making it smoother and the sanding marks aren't as noticeable.

[scottp55]

Thanks Don, Was concerned about the accuracy. Gotten into the habit of RO sanding the boards in between 3 of the bit changes and then a final 320G before unscrewing as it's easier than sanding the 12 5X5" pieces and only have to radius and sand edges. So no big difference between sanding mill marks or sander striations. Thanks

[gc3]

forget the drum sander a oscillating wide belt machine is the way to go...

wood moves with moisture changes expecting to achieve .002 to .004 results can be a challenge...

T movement is greater than R R is greater than L

[Burkhardt]

Gert - on getting your boards flat the simplest method is to buy a drum sander. Once you have one you will wonder how the heck you existed without it!

Noooo. I must resist.

But maybe if I move the washing machine and dryer out of the garage I could still fit another wood working machine? I will try to explain that to my wife. Washing in the driveway is not so bad for Southern California.

On the serious side I could probably optimize and kick out some stuff I never use. Problem is the affordable drum sanders are a bit on the small side and look kind of flimsy (no objective evidence, though) and I could not justify a pro machine for my occasional use. But thanks for the hint. Maybe I should just build one.

[myxpykalix]

Because i don't fully understand your concept of how you are writing this program, what i think am decyphering for this conversation is that your material can't be out of whack by 2-4 thousandths hence the talk of the expensive sander.
I don't have one of those and the shopbot isn't even that accurate to 2-4 thousandths (at least mine isn't) so my question is...
Can you program each separate finger joint side to correspond to that pieces thickness OR
could you cut your individual finger joint sides to also include the thickness of the adjoining piece thereby eliminating the need to have the whole piece sanded or milled?
I hope you can see the line drawn on the piece indicationg the part that would be included in the cutting, and hopefully you understand the point i was making.

Also by cutting it "from table surface" rater then from "material surface" and have your fingers set at a specific thickness, wouldn't that eliminate thickness errors?

[Burkhardt]

......wood moves with moisture changes expecting to achieve .002 to .004 results can be a challenge...

Maybe I was not clear about that. I was talking about 20/1000" or 0.02" or half a millimeter. Anyway, that means a distortion where the glue is not going to fill the gap and you can see the error. Obviously the machine does not know that the board is warped and this is just the resulting gap (or interference). It is not so much a problem with my software but a general accuracy issue.

[Burkhardt]

.....Can you program each separate finger joint side to correspond to that pieces thickness OR
could you cut your individual finger joint sides to also include the thickness of the adjoining piece thereby eliminating the need to have the whole piece sanded or milled?

The software settings can be chosen for different thickness for each side and match up perfectly in a perfect world. Unfortunately, the boards are usually not that perfect. That is where I have the problem when warped or cupped. But I see that some folks her solve it not by forcing it flat but sanding flat. Got to think about that.

Also by cutting it "from table surface" rater then from "material surface" and have your fingers set at a specific thickness, wouldn't that eliminate thickness errors?

That is actually what I am doing right now. The zero is on the table surface. But it does not help if I specify 0.75" thickness for a board and it is 0.75" away from the surface on one side and 0.78" on the on the other side.

[khalid]

Khalid: I am almost embarrassed to admit but I never got the hang of VB or other more modern visual tools. All my PC code is written in text based Liberty Basic (and compiled with the R.T. Russels' Liberty Basic Booster tool). It makes the GUI a bit more work since it is not as simple as dragging boxes on the screen but I have all the code in one piece. I am just not a professional and old dog refusing new tricks. For microcontroller code I use Forth, an even more arcane programming language.

Ohhh ....Thats a hell of work you doing then. However, this make you a perfect programmer. I bit you can program anything what you have in your mind
If you learn Visual Basic then you can make a CAD/CAM software without spending too much time on GUI
I really appreciate your efforts and programming skills

[Burkhardt]

You guys are bad company. It never occurred to me that I need a thickness sander. But since some of you mentioned it and I had a bit of trouble getting the boards flat enough, I ordered a drum sander. Oh well, I am telling my wife that will help keep me busy in retirement in a few years.

Obviously I can not afford one of the nice professional machines (or would have the space). But looking at reviews for moderately priced machines I opted for the Jet 16-32. I hope this is not a toy but let's see how far that will get me.

I did cut the parts for my first real project. Since the program is not totally reliable yet I used simple 1/2" BB plywood. I will do the next project in some prettier lumber.

This is a simple 14" x 9.5" x 4.5" box. My software makes the tool paths for the 4 side boards including joints, bottom/top rabbets and side cutout. There is still a bug making the rabbet come out to the side (see 2nd pic).

I used VcarvePro for the top and bottom as well as for slicing the lid off the finished brick with a 1/16" x 2" dia slotting cutter in the spindle. Now, I hope nobody will tell me I need a table saw to do that better.

[scottp55]

Here you go G. (For your new cabinet saw)