Fixture material

[geraldmorrissey]

I an going to start the building the empennage fixture soon. MDF or plywood? Layout the left and rt hand assys or just one half? Got Eric's book coming but curious how others have gone before me. Wing spars are finally finished. Itching to get into some steel. Have all required good ole Amerkin steel tubes and factory ribs at the ready.
Gerry
Patrol #30

[Ejs014]

I’m building a 4 place but the build is probably the same. I laid out the drawing full scale onto my 4 x 8 workbench with 3/4 plywood top. I bent tubes to fit lines. I used small pieces of 1x material to position and hold pieces in place by screwing the wood pieces on each side of the tubes or ribs. Tack welded and slowly finish welded to ensure everything stayed flat to the table. I did one side at a time.

[BTAZ]

Avoid MDF for things you are going to be welding on while fixtured as(when smoldering.) it is really unpleasant smelling

[davzLSA]

I agree with Btaz on the MDF, use the 3/4 plywood. Also use the same jig for left and right horizontal stabs, it will ensure they will be identical. Same goes for the elevators, Just my 2 cents, Good luck on your build.

[sbmurphey]

Fully agree with the above comments that burning MDF is no fun to work around. I am a plywood fan for most construction projects.

However, a tip a local ol'timmer gave me was to use MDF as you get a smooth straight work surface. Then lay down a replaceable layer of sheetrock for a top (white side down if spanning tubing over the edge of a sheet). Was nice to layout on a nice clean surface and you could tack weld near it without setting the table on fire. Used a drafting compass set to the radius of the tubing to place my blocks. Finish nail the blocks to the table and you are ready to layout tubing. Worked so well, I would do it again even if I had plywood tables.

Best of luck on the fuselage. Was one of my favorite parts of the the build to date.

[geraldmorrissey]

So let me see if I got this right, the brown fixture surfaces in the pictures are the back side of sheet rock panels? I will be tack welding with a oxy/acetylene torch. Will that set the paper on the sheet rock on fire? Did you tack in the fixture and remove the assembly for final welding? Did nailing the blocks on crumble the sheetrock? Seems like screws could work too. Sorry for all the questions but I find this method intriguing. I use sheet rock for a building surface for my model airplane activities. It's a very useful, cheap and disposable work surface.
Gerry
Patrol #30

[sbmurphey]

Yes, the brown is the back of a sheetrock panel. Using the back side keeps all of the sheets on a level plane as the taper on the edges of the sheets are turned down. It burns a little under direct heat, but it goes out when you pull the torch away. All of my fixtures were tacked and then removed/offset an inch or so from the table for final welding. The finish nailer worked fine on the first pass. If you moved the block two or three times it started damaging the sheetrock. I did use screws and nails in some places. E.g controls, rudder pedals and anywhere I needed a little more strength.

[alaskabearhawk]

I just used 3/4in plywood. Seemed to work well for me. I agree about the MDF. It's just a bunch of glued sawdust and really stinks when it burns.

http://www.mykitlog.com/users/category.php?user=yeeeha&project=527&category=7248

About 160 log entries. Scroll down just past the halfway point and the entries for the tail bits start to appear.

If you want to make the profiled ribs there is a three-part video series how I did it. Part 1: https://www.youtube.com/watch?v=rUyTOwfnQiI&t=9s

YMMV.

[Glenn Patterson]

We built our tables with 3/4" shop grade birch plywood tops as it gives a great surface and can be less expensive on sale than 3/4 G1S plywood. We painted the table white. I used a draftsman's method of making an accurate grid if the scale on the drawing is off a bit. For example if 2 critical points are dimensioned at 20 scale units measures at 18 scale units then the copy is not at accurate. Parallel lines are drawn through the 2 dimensioned points. The zero end of the scale is place on one line then the scale rotated until the 20 mark lands on the other line, place a tick at each increment then draw parallel lines through the ticks. Then do the same in the perpendicular direction. That will show exactly where all the curves pass through the grids and it is easy to repeat on the table. We painted the table top white & drew the grid on. I have a long tee square that I used to draw the grids but a person could do the same with a 4 ft drywall square. We used finishing nails to hold the parts. The tubes curved to be a nice fit to be dead accurate w/o using jig blocks to force the shapes. The same set up can do left and right horizontal tail. Attached are photos on the jig, the parts stacked to see they are identical. I used the same method to do the rudder. I have attached a photo of the grid overlayed on the rudder and what it looked like on the table. We painted the tables white for each set up. We cut the legs to lower the tables and installed a 4 foot bridge between the 8ft tables, painted them all white then drew the top and bottom fuselage on it in opposite directions so they did not get mixed up..