How flat for a building board?
07-09-2008, 02:45 PM
#26
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RE: How flat for a building board?
My table is made with an inside hollow core door countersunk into a 2x4 frame/legs making a 6'8" pretty dern flat work surface. No more than a 16th of an inch off flat (measured w/ 1m s/e) at its worst. Ceiling tiles are used for sticking pins into but I have built small projects directly on the door surface. Pins are harder to insert but work this way too. Can have more than one project at a time on this one.
Also use a few aluminum straight edges (1ft to 1m) I made when I used to run an aircraft sheetmetal department to keep things straight.
Terry in LP
Also use a few aluminum straight edges (1ft to 1m) I made when I used to run an aircraft sheetmetal department to keep things straight.
Terry in LP
07-09-2008, 04:38 PM
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RE: How flat for a building board?
A hollow core door will usually be flat enough for most practical purposes. If you want the ultimate in flat building surfaces I would suggest you build a torsion-box table. It can be built quite simply using MDF-board. Here is an example:
[link=http://www.diynetwork.com/diy/ww_materials_products/article/0,,DIY_14442_2278181,00.html]DIY Torsion Box[/link]
[link=http://www.diynetwork.com/diy/ww_materials_products/article/0,,DIY_14442_2278181,00.html]DIY Torsion Box[/link]
08-31-2018, 08:01 AM
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My building table is approx 10 years old now and still nice and flat,
You may think this is overkill and maybe it is but here you go. I built a frame for the table 3'x8' the perimeter of the frame is 2"x6" with 2"x4" joist 12" on center. The table top is 3/4" finish grade ply and the legs are 4"x4" with 3/8" lag screws in the bottom for leveling. All the joints in the table were screwed and glued. I can move the table anywhere in my shop and re-level it in just a few minutes and it stays flat. I also have a piece of tempered glass that I put on the table top to build on. This may seem a bit extreme but if you want a straight airplane you must start with a straight building table. I have maybe $100 invested in the table and it has been worth every penny.
Anthony
You may think this is overkill and maybe it is but here you go. I built a frame for the table 3'x8' the perimeter of the frame is 2"x6" with 2"x4" joist 12" on center. The table top is 3/4" finish grade ply and the legs are 4"x4" with 3/8" lag screws in the bottom for leveling. All the joints in the table were screwed and glued. I can move the table anywhere in my shop and re-level it in just a few minutes and it stays flat. I also have a piece of tempered glass that I put on the table top to build on. This may seem a bit extreme but if you want a straight airplane you must start with a straight building table. I have maybe $100 invested in the table and it has been worth every penny.
Anthony
08-31-2018, 07:23 PM
#29
WacoNut’s last activity was 11-27-15. This is an old thread. If you want a flat surface, building a torsion box is the way to go. Do a search for images torsion box construction and you will see many examples.
I built a torsion box for my build surface. I used a ¾” melamine sheet for the top. Standard lumber iirc. I also added screws for adjusting to flat if it ever got out of adjustment. No adjustments in 4 years since I built it. I check for flat before each build. I use a drywall sheet on top for the actual build. The torsion box is on an old kitchen cabinet unit which is on wheels. It can be moved around and you can work from all sides. I have a couple of inches of overhang on the melamine on all sides for clamping purposes. Has worked great 4 years now.
The leftover melamine I used for a table for a wing jig I made. All the melamine was used.
Here is a picture of a torsion box.
I built a torsion box for my build surface. I used a ¾” melamine sheet for the top. Standard lumber iirc. I also added screws for adjusting to flat if it ever got out of adjustment. No adjustments in 4 years since I built it. I check for flat before each build. I use a drywall sheet on top for the actual build. The torsion box is on an old kitchen cabinet unit which is on wheels. It can be moved around and you can work from all sides. I have a couple of inches of overhang on the melamine on all sides for clamping purposes. Has worked great 4 years now.
The leftover melamine I used for a table for a wing jig I made. All the melamine was used.
Here is a picture of a torsion box.
09-01-2018, 06:36 AM
#30
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Ditto on the torsion box method. A kid who worked for me years ago built one for me. It's traveled from Texas to Germany to Virginia to Michigan. At 35 years old it's still flat as can be. Top surface is particle board and I use ceiling tiles to build on. Never a problem.
09-01-2018, 08:22 AM
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Ditto on the torsion box method. A kid who worked for me years ago built one for me. It's traveled from Texas to Germany to Virginia to Michigan. At 35 years old it's still flat as can be. Top surface is particle board and I use ceiling tiles to build on. Never a problem.
09-02-2018, 06:14 AM
#32
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The kid knew what he was doing with wood. Too bad he was also a dope head and we ended up throwing him out of the Air Force. He was also functionally illiterate. He could read but was very, very slow at it. I hope he found a nice cabinet shop where he could do what he enjoyed and was good at.
09-13-2018, 10:30 AM
#34
I also went with a torsion box. I built it so that it can be folded up against the wall when not in use. There is a second set of legs that folds down so I can use unpin from the wall and use in the middle of the floor. Adjusting nuts and bolts are welded to the bottom of the legs. The bench is 8' x 3.5' and you can grab one end and start lifting and the other lifts immediately with no twist. A 6' level across the board on any angle, no light underneath.
