OK tool Guru's, I could use some help - RC Groups
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Feb 09, 2003, 09:22 AM
Registered User

OK tool Guru's, I could use some help


Being a kit manufacturer I'm always trying to come up with ways to make things better and more efficient in terms of time to produce and better finished product. One real pain in the butt is tails, or better phrased, tapered sheet stock. I use 4" contest grade wood for sheet tails in several of my kits and all have airfoiled tails. Whether finished (either bagged or covered) or in "kit" form it is way better to get the wood as close as possible in "machined" form before going to hand work. The sheet wood is as thin as 3/32nd up to 1/4" I currently have made a bunch of tapering jigs for a 4" belt sander that I have which helps a lot but leaves a lot to be desire. Is anyone familiar with drum sanders?
Will they do tapered sheets? It would seem to me that if a drum sander can be set up to do tapered stock it would be much quicker than the current method which requires several passes by hand and would also be more accurate. I do a lot of this stuff including cutting my own aileron stock in order to be able to control exact sizes and shapes and to also control wood quality and weights. Any other ideas or suggestions would be greatly appreciated.

Denny Maize
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Feb 09, 2003, 10:33 AM
Cal Slope Criminal@DV
Duke58's Avatar
Denny , no "Guru" here but I've been to a couple of Mahoning County Fairs, I'd think a plainer would do that, some have power feeds also.

Feb 09, 2003, 10:44 AM
Registered User
A number of years ago Sears sold disk sanders in 8 and 10 inch diameters for applications on table saws. One face was a 5 degree from flat cone and the other face was flat. The idea of the cone side was to tilt it 5 degrees so that the cone was perpendicular to the table and stock could be fed into the shallow cone to sand it to a right angle. I used it to taper pairs of 1/16 sheet trailing edge stock to a feather edge with a bevel width of 5/8 inch. It worked extremely well. I made a plywood fixture that snuggly captured the unbeveled stock but allowed the stock to slide smoothly through into the sanding disk at the desired bevel angle. It was necessary to support the stock a little past the last contact with the sanding disk to limit stock vibration and to get a precise bevel. To shape the fixture to match the sanding disk, I fed the fixture perpendicular to the disk to sand away a portion of the fixture that corresponded to the crossection of the stock to be sanded away.

Lately I've been looking for such a sanding disk to repalace the one I gave to one of my grown kids about 15 years ago but haven't been able to find one.

I think the job could be done as with a good sized drum sander in a drill press. The trick is to build a wooden feed fixture for the stock and set the fixture up to the drum so that the stock is supported every where right up to the drum and a little beyond. the outfeed of the fixture could be partially plugged to allow for the material being removed from the stock. This would capture the shaped stock so that it didn't vibrate or warp out of position.
Feb 09, 2003, 11:56 PM
B for Bruce
BMatthews's Avatar
I see a drum sander with a lowered table to allow a hollow box fixture to pass under. This fixture would have multiple control surface shaped depressions that fit the blanks for the surfaces in question These depressions would have angled bottoms to match the taper design. The bases of these "sockets" would be perforated to allow a vacumn to hook up to the fixture box and suck the blanks into place. A few extra holes here and there could assist the dust collection that would be so desparatley needed... Or just make the fixture the whole width of the drum to let the shop system do it's job properley. In use the fixture would be just skimming the drum so there would still be a pretty good seal to the collector header.

Passing the fixture under the drum so that the horizontal sanding pressures on the blanks force them into the deeper part of the sockets would ensure no one jumping ship. The fixture could take any number of surfaces across and in train depending on how large they are and how large a vacumn fixture you wish to deal with. I see 4 or 6 stabs at one go being typical with a 24 inch wide sander. Orient the sockets in the top plate at angles such that the entire face of the sanding drum is used on each pass to prevent undue clogging of the paper and so that the drum is not expected to take a huge bite at any one time. This would also limit the forces on each surface to a smaller area and hopefully prevent them being rolled up and eaten.

Depending on how much balsa you're chewing off at one go it may be necessary to take two or three passes with each pass being lifted up progressively towards the final sizing. Or just limiting the feed speed may do it. Angling the surfaces so the stronger long grain takes the forces couls limit the possibility of the balsa blanks rolling under the drum.

If this sounds interesting but I'm not making total sense PM me and I'll see if I can do up a sketch for ya.

If this works do I get a big fat discount on a kit?....
Feb 11, 2003, 08:16 AM
Registered User

Lots of ideas to think about. I'm trying not to over complicate this project but some things like the vacuum board to hold work are very interesting to me. A lot of the 3/32nd stuff will curl like crazy when tapered. Makes it hard to do an accurate job. This is not a "mass" production job but rather a couple times a week at worst using a couple dozen sheets. I don't mind doing one sheet at a time but rather am looking for more accuracy and better finished product. Seems like the drum in the fixture deal could be either horizontal or vertical. Keep em coming:-) Thanks
Feb 11, 2003, 04:15 PM
B for Bruce
BMatthews's Avatar
For that number I can see where my sanding jig would be overkill.

What about a vacumn table once again but this time you use stratigically placed wires to support the sole of a long bodied razor plane and series of sanding blocks? The plane would used single edged razor blades and the sanding blocks would only be papered in the central working area. The wires would provide the limits to the work and stops would control where the blanks were placed. And the vacumn fixture could have some holes around the edges to suck up the dust as it was created. Using the right paper sequence you could probably do a control surface in as little as 12 strokes. That 50 grit is real harsh isn't it. Shims on the sanding bodies could control the depth of cut for each paper so it would be totally controled with the surface in one fixture. You could use sandpaper for the whole operation but I like the idea of shavings for the first shaping. Actually I don't see why the razor plane wouldn't do the whole job with just a little finish sanding to remove any blade ridges or lightly torn areas.
Feb 11, 2003, 04:25 PM
Registered User
In the end, the fixture you first described would likely be the best way to go. That could actually be set up to do multiple tapers, etc. I think I will stick with my jig that I have now till I get time to get that inventive. I do think a drum sander will come into play at some point as I do more and more wood kits Probably 2nd on my list right after that cnc router table I havn't had time to build:-)
Feb 11, 2003, 04:47 PM
bob h
Hi Flyin,
You did not say how much you wanted to spend but, there are thickness sanders that are sold by most of the wood working supply houses. "Performax" is one brand of machine. They are basically drum sanders that are adjustable for thickness and have a feed belt that moves the work by the drum. You can get a variety of different sanding grits. The price runs from $1k up. Not cheap but they do a nice job for sanding to thickness.
Feb 20, 2003, 07:52 PM
slow but inefficient
Ron Williams's Avatar
Hi Denny -

If you're going to the WRAM show, stop in at the Aerocraft booth and talk to Bill Schaefer and Craig Wagner. They've been cutting balsa since who knows when are are used to thinking in terms of simple set-ups to do wierd things to balsa. They'll probably be bored sitting in their booth and love to compare notes on stuff like that. I'm always amazed when I visit their shop and see them doing things to balsa I thought would never work.

Feb 20, 2003, 08:02 PM
Registered User
Hi Ron

I had plans to attend the show on friday to deliver some planes and meet some friends. Kinda had a family emergency come up that's taking me out of the shop for a week. I did get to ship yours this morning. Keep your eyes open for it sat or mon. USPS priority mail.