All that for $300?? Good luck.
I wanted to pop over and ask if I could get anyone else interested in helping me design and construct an open source design for a wide sander. There are several engineering challenges to doing such a project that I figure a community like this may be able to come up with some novel solutions.
1. Must be able to be constructed to sand 26"-36" widths.
2. Must be able to be power fed.
3. Must be able to be constructed for under $300 in parts.
4. Design must be free and open.
5. Must have .01" accuracy
1. Changeable drum/sleeve.
2. Easy paper change options using inexpensive paper.
There are 2 basic types of wide sander, drum and wide belt.
From the research I have done ( google) I have not found anyone who has been able to build a wide belt sander. The reasons for this I suspect are that in order to keep the belt tracked on the rollers you need to implement some complex behavior with mechanical or optical sensors to track the belt, and most people who are attempting to build such a machine do not know much about control systems. A wide belt machine typically has 3 or more rollers, and a single very flat “platen” which is used to contact the work piece similar to a belt sander. The benefit of this design is in accuracy and ease of changing grit. With optical mice so cheap, I can imagine they could be used for the tracking, but if it gets dusty it’s over. You would also need some way to move the angle of the pulley to keep the belt tracking with the resistance of the work below trying to pull the belt off to one side.
The other big challenge is a power feed option. Most home built machines are hand fed which may or may not lead to issues with accuracy.
Is anyone interested?
I have setup a board for those who are interested http://stink.net/sander
Last edited by greenail; 01-15-2007 at 01:50 PM.
All that for $300?? Good luck.
Why not build a drum sander?
Are you sure there is an active tracking system in wide belt sanders? Not just a slightly crowned drum somewhere in the system?
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As far as drum sander design there are 2 types I have seen:
Top Fed if you already have a power feeder (they run between $350 and $900):
And the most common bottom fed
You could also do a multi drum design, though I'm not sure how much accuracy or benefit this gives you. I've never seen one and i'm sure it just complicates the design.
I built the sander from ShopNotes last year but soon discovered that it is too small for any significant work. I think it was only 16" wide at best. I too want something bigger and have been thinking about this for months. I also want a power feeder on it and I figured the best way to do that was to use a geared down motor turning a roller which has a large sanding drum paper on it. The largest I found was something like 24" wide which would be perfect. I also found a source for the rollers with attached sprockets on the ends so it could be hooked up with a chain to be spun by the motor. The drum design is pretty straightforward. The other part that needs some attention is the whole raising and lowering of the drum/and or table to set the thickness to be sanded. Most commercial units raise and lower the drum and the conveyor is stationary. The only way to do this would be to manufacture the machine out of steel and have to do some welding... I didn't want to get into all that.
I would be glad to help out any way I can since I am looking to build one also.
this post for how I think you may be able to do a feed. I also think polyurethane feeders would work best.
BTW if you can use sketchup visual explanations are quite helpful.
I intend on building a drum sander with a conveyor. The question I have is on the drum length. I intend on using a low RPM motor (10-20 rpm) turning a sanding belt as the conveyor. The standard sizes for belting are 25 x 60, 36 & 37 x 75 and 30 x 103. Custom ones generally are twice the price, but still are relatively inexpensive. My intentions are to build two drums(each with different grits), but to only use one at a time by switching belts. Therefore a longer frame would be desirable. At the same time it would be great to be able to make and use the maximum drum length possible.
The question is why should I not build a 36 inch drum? The drum will be 5 inches made from Baltic plywood epoxied to a 3/4 inch shaft. The shaft length for a 25 inch length drum will need to be 36 inches to accommodate the pulleys, pillow blocks and the clearance for the conveyor system. The 36 in drum would require a shaft of 48 inches. In each case from drum edge to the edge of the pillow block bearing will be approximately 5 inches.( by adding an additional brace on each side I can get this down to 1 inch) the edit.
In either case the drum would be powered by a 3hp motor and spinning in the neighborhood of 3500rmp.
The full width will probably be used infrequently, but width in excess 25 inches relatively common.
The main concern I have would be the deflection of the shaft. I think there would be little concern in the area of the drum, but from the drum to the pillow blocks. The longer the drum the more mass spinning, thus the more possibilities for problems.
Can anyone give me any type of definitive answer?
Last edited by stetwood; 05-08-2007 at 12:02 PM. Reason: A second look at the plans
I believe a 3/4" shaft is much too small for this machine. I built a somewhat similiar machine once but used a 1-1/4" shaft inside 6" PVC pipe (the PVC pipe was the drum). The machine worked but I did not have power feed (really needed) or dust collection. Lack of a good dust collector was a deal killer, don't start unless you have a GOOD dust collection system.