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Random orbital sander CNC Housing and fitting to surface HELP

5876 Views 8 Replies 7 Participants Last post by  epicfail48, 
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The project is moving slowly but surely. I wanna create a CNC machine but with random orbital sander on the head of the CNC. I will move in two axis like on picture below.
I made some SolidWorks model ob the machine. I also made the physical metal construction already but I stopped cause of some problem.

I need to make some enclosure for my Bosch RO sander. That wont be a problem. A problem will be with moving the machine's pad strictly parallel to the wood which it will sand. If the wood will be in a little angle against sander's pad there will be a problem.

So i have to make some moving joint in all the ways. Like on picture below:


But this joint could be montaged on the top of the machines enclosure. Is this too high?

PLEASE give me some idea how to make my machine's sander pad fit to the workpiece no matter whats the angle between workpiece and sander's pad! Maybe 4 springs and the bottom of the aluminum housing of the RO sander? I dont have much mechanical knowledge so let me hear the ideas!

THANK YOU SO MUCH!:thumbsup:

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F
Why not simply shim the material being sanded, similar to what you would do with a thickness planer, so the top is level, I can't see how it works otherwise with only X and y axis movement.
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woodnthings
ideas....

To make the sander press down evenly on the workpiece you could:

Use an air bag or air cylinder with very low pressure.

Use pressure springs at each corner of the housing with a counter weighted arm to release the pressure by lifting up when pressed down. The same function could be done with a small air cylinder.

Use a platten which supports the sanders base which of it's own weight gives an even pressure. More weights could be added to increase pressure.

You could put height/depth limiting, non=friction, pads on the outboard corners of the housing to restrict the downward travel.

I don't know, but the sanders' pad may be "self leveling" with no need for minute adjustments...?

I am assuming you want to lift up the sander when replacing the material with a new piece each time?
Then apply a similar downward pressure for the next piece...?

You could leave the sander in a fixed position and raise or lower the work using a frame with a camover center mechanism, four bar link or other such design... which locates it at a fixed height and which can be released easily, in other words, move the work, not the sander.
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Why?

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F
This is confusing, looking at the drawing you show arrows indicating three axis but state it will move in two. If it only moves in two axis then the pad has to be parallel to the material being sanded no adjustment necessary.
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BZawat
Yeah I'm missing the point. Why go to all the trouble to build a CNC machine just to handle an orbital sander? Seems like an enormous waste of time to me. A big part of finish sanding is "feel", and I doubt you're going to be able to duplicate that in a mashed-together rack that holds a hand-held electric ROS.
I don't mean to be negative, just missing something I guess?
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B
Ideas

Thanks for anwsers.
The head will move with stepper motors in two directions (x and y - red and yellow arrows). It will also move in Z axis (green arrow), but with no motor on that axis - it will be just linear rail with some weights optionally to set the right pressure on the working piece. (Maybe the weight of the RO sander and its aluminium housing will be enough).

The reason why I wanna make take machine is: I make cajons (Cajon - wooden drum - google it). So I wanna sand all the 6 surfaces of the drum which is already glued together. I will just turn around the drum to sand each surface.

The best solution is maybe: I will use the linear rail for Z axis (green one) to move the RO sander and its aluminium housing up and down (with no motor, just force of the RO sander's mass) - regulate pressure to the working piece.
And for fitting to the surface i would montage 4 springs on the bottom corner of the aluminium housing of RO sander.

What do you think?
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Dion
BZawat said:
Yeah I'm missing the point. Why go to all the trouble to build a CNC machine just to handle an orbital sander? Seems like an enormous waste of time to me. A big part of finish sanding is "feel", and I doubt you're going to be able to duplicate that in a mashed-together rack that holds a hand-held electric ROS.
I don't mean to be negative, just missing something I guess?
Click to expand...
This is a good question. I'm thinking of building something like this to save time when finish sanding large flat panels. My routine is twelve passes at 100, 150, and 220 grit using just the weight of the sander and the suction from my vacuum to get to a ready-to-finish surface. For big projects, this is a huge time sink. Imagine if I could just set it up and push go, coming back every few minutes only to change the grit or the workpiece, for a fraction of the cost of an expensive floor model belt sander, which seems to be the only commercial alternative.
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epicfail48
Not to be a wet blanket, but that sounds like a whole lot of overkill, expensive overkill at that. By the time you finish building that, and all the hair you tore out grows back, you couldve just bought yourself a drum sander and called it a day several times over

CNC is great and all, but straight lines in a single plane make it a waste of time and effort to CNC something
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