NorthernBoy

My Feedback: (1)

For my next project I need to make a 80" wing in one piece, thus I need a large straight, flat building board. In the past I have used hollow doors for smaller wings, but I find them not be truely straight and flat. Any recommendation here for a large building board. I was thinking of using 1/2" plywood with sheet rock on top and a frame underneath to strainghten the plywood and give it strengh. But not sure what to use for a frame, wood is never perfectly straight.

Thanks
NB

the-plumber

Dunno how 'permanent' a building board you want, but I finally gave up on hollow core doors (and doors in general) and built what may be my last building table. Dead flat, plenty large, and tough enough for just about any model building project. You could easily adapt the design to any size, up to 4' x 8' or even larger. It's on my web site under "Photo Albums", "Torsion box building table".

Jimmbbo

In the mid 80s, I made building boards from 12 inch wide luan veneered particle board shelving with 1/4 inch thick bulletin board cork contact cemented on one side. I made three boards - 6', 2' and 1' long - for wings/fuselages, horizontal stabs/elevators and vert stabs/rudders. Since I build mostly with aliphatic resin, having separate boards allows me to build a section and put the assembly aside to dry while I go on to something else...

You could get a longer shelf for your 80 inch wing, and while I have not had any straightness issues, you could install two or three 1 inch square aluminum tube stiffeners along the length of the bottom of the board if you prefer.

Since the shelf material is cored with particle board and have no grain, they have stayed flat over the years.

Cheers!

Jim

Love1/4Scale

My Feedback: (26)

If you wanted to stick to doors....use a solid core door. A 2'6"x7' door works perfect. Also, check your phone book for local door suppliers. Bundles of doors are usually shipped with a solid core "beater door" on the bottom (and sometimes top) to prevent damage to the other doors. At one time I had made 3 workbenches from these that I got free of charge. Ended up leaving them for the next tenant when I moved out of the area [:@]

JL636

My Feedback: (79)

For my building bench I used a sheet of 3/4" ply and ripped it down the center for a base. Then I bought a hollow core door for $25.00 and fastened it down to the ply. Then I put two ripped sheets of cellotex down. Now I have a long term building board that can handle wings up to about 90" and the cellotex lets me pin things down with no problems.

mulligan

What is Cellotex?

dicknadine

Ceiling tile. make sure you get the Non perforated ones. also there are commercial building boards available with Balsa tops. mine is 19x76, beleive Tower has them, check your magizines. dick

Love1/4Scale

My Feedback: (26)

Ceiling tile as Dick stated will work fine but I think the cellotex JL636 is referring to is the 4'x8' building material board. Cellotex is a brand name and there are several different types. The black expansion joint type cellotex seems to hold pins well but the foam/foil face cellotex does not.

dicknadine

while your at it, plan on making 2 big boards--1 to draw big plans on and 1 to build the planes on. the plans one is plastic counter top sheets.all different brands, try to find a white colored one. you have the info on the building boards. dick

tucker1865

My Feedback: (6)

NB...GET A SHEET OF MDF (MEDIUM DENSITY FIBRE BOARD. ITS THE FLATEST THING OUT THERE EXCEPT FOR GLASS. PLYWOOD WONT DO IF IT HAS TO BE FLAT AND 1/2 INCH IS EXPENSIVE COMPARED TO MDF. ITS LIKE PARTICLE BOARD BUT MUCH MORE DENSE AND FINER GLUED PARTICLES. YOU COULD COVER IT WITH A SHEET OF CELOTEX IF YOU NEED TO PIN IT. CELOTEX IS WHITE AND USED FOR BULLETIN BOARDS. HOMASOTE WORKS WELL (GRAY) BUT I HAVE NOT SEEN IT FOR YEARS. DAVE

dirtybird

My Feedback: (5)

If you really want a flat straight board get a foam filled metal door. Then you can use magnets to hold the work in place. Someone even made a special set of magnets for this purpose.

rajul

My Feedback: (58)

Here's how I braced my wood building board. I fastened 1" hollow aluminum square bars to the bottom all along the edges and an additonal piece across the width in the middle. I just used three self tapping wood screws for each bar and added rubber inserts at the ends of the bar which prevents gouging of your work table by the corners of the bars. Hope this helps........

jwalsh1

I just finished one that will allow for 6' pieces, but you could build it as long as you want. Its been pretty darn flat now for about a month without moisture absorbtion from the basement.

I built a frame of 1x4 pine 6' x 2' and placed 5 ladder pieces for support. I then built legs from 2x4 and 1x4 diagonal braces, and this formed the base upon which the actual building surface is attached. Its so strong you can stand on it without it moving at all. Make sure the diagonal braces from the legs to the table support the table near the mid span. This will help prevent the table top from sagging. The fact that its only 2' wide prevents it from sagging in the short dimension.

I then bought smooth back "Hardy Panel" fiber cement board and cut it to the size I needed. I used liquid nails to attach that to the 1x4 ladder frame and let it cure. I then sent this table assembly (1x4 frame + fiber cement panel) and passed it through a huge flatbed sander we have here at work, but you could simply use a straight edge as a gap finder and sand it in spots till its flat.

Finally I bought a sheet of drywall and placed it on top, and screwed it to the fiber cement. I found this is a pretty good pinnable surface, and easily replaceable.

The advantage is theres essentially nothing in the assembly that has any real level of moisture absorbtion to cause any warping, so no matter what the humidity in the basement is, the table stays flat. So far I can lay a straight edge anywhere and anyhow on the table and I dont get any gaps between the metal straightedge and the table when checking with a flashlight.

The problem I had with my MDF tables is when MDF takes on moisture, it expands essentially equally in all directions. BUT, if you have that screwed to a table or something, then it cant expand in all directions and suddenly it warps as it takes on that moisture. Ive run tests and found that even having something attached to one side (in my case a pinnable surface) but leaving the MDF itself floating, the MDF on the side covered doesnt take as much moisture as the uncovered side and that creates an unbalanced moisture absorption, and hence causes warp. In fact, if you simply clearcoat one side of MDF and leave the otherside uncoated, the panel will warp badly with time. IMO the best way to prevent warp is to use materials that dont absorb water well, or materials that absorb water without expanding.

Hollow core doors never worked for me because no matter how you tie it down, the middle is hollow and the two skins will "oilcan", or become concave between the frame of the door. Since you cant get to the inside of the door, you arent going to be able to effectively prevent that no mattr how the perimeter of the door is supported.

lunbom

If a lightweight board that is easy to store when not in use is your desire, then try this; rip a piece of MDO ply to, say, 16" and fasten it to an ironing board. Used ironing boards can be found at Goodwill and similar stores for next to nothing. It works for me.

dicknadine

add this to the list, glue the ceiling tiles to plywood and then start using the dinning room table as your base. that is providing the wife is out of town and not aware of it. it works. dick

jwalsh1

at above.

Griffin_NC

My Feedback: (3)

I do the same things with my building board Dick. Just have to make sure you get all the balsa dust cleared off the table before she returns. I got busted one time when you found some that had settled under a place mat.

tucker1865

My Feedback: (6)

Walsh...Is you basement flooded, seal the MDF with Urethane, not water based (it will take multiple coats) or get the MDF with a mylar face (yellow) at a lumber company. I dont think Home Depot carries it. Seal the edges. You must seal both sides to prevent warpage and same if you glue something to one side. If you use celotex, screw it down, no glue and it can be replaced easily. The drywall method is a good idea. I have never seen MDF warp, but I live in California and the humidity is relatively constant where I live. BTW...there is also melamine, It is coated MDF.

jwalsh1

Yes, you are correct, properly sealed MDF will really help get rid of that warp. Part of my problem was the supports for the MDF I used, and it sagged. I also got tired of sealing and just wanted to try something different.

I live in a pretty old house with a decent, but old basement andif it rains ALOT, we get some seepage in. It doesnt flood, but it isnt exactly the driest place in the world. I envy you guys with comfy dry basements. Humid days = humid basement, and the humidity level in my basement varies greatly, even though I use a dehumidifier. Essentially I found that whatever the humidity level is outside, it is in my basement too. This is why I have some warp problems (and I probably didnt do as good a job sealing my MDF as I should have). At some points during the summer I was emptying my de-humidifier once a day.

You bring up a good point about screwing the pin surface down, not only is it easily replaceable, but you dont create that unbalance which could cause the warp.

I looked at the melamine, but I wasnt comfortable with one side having a laminate and one side not having it. Even if you seal it, you have to make sure its really well mounted to prevent it from warping. I just thought there might be a different way. The melamine is pretty cool though because you could just buy countertop seconds that the Home Depot wont sell for next to nothing and have yourself a pretty big board.

I should have prefaced this with I just started scratch and kit building and I really dont know just how flat flat means. You hear everyone say it has to be dead flat, but thats really hard to achieve, there has to be a level of tolorance in the somewhere. I just dont know what that tolorance is, so I built something that was probably waaaayyyy overkill.

dicknadine

level and flat are synonomous in the building board- ie no warps, sags, etc, corner to corner. what we are trying to tell all is that the board shud be FLAT in ALL directions. the sub surface can anything strong enough to support your elbows while you work on it. put it on the floor- that is if you can bend over it very long. SIMPLE DOES IT.. stay away from the complex. fortunitly this one thing that the computor can NOT do. old timer Dick

firefighter56

In Fla. we don't worry about basement flooding, we just use our boards as hurricane shutters

jwalsh1

Surely there has to be some level of tolerance in the "flatness" though. I mean if you took a straight edge to your dining table, theres got to be very small variations in the surface that would show up as slight gaps between the straight edge and the table. What is acceptable as these slight gaps? I know you should minimize them, but theres no way on earth one could build a board that is absolutely 100% gap free flat, and stays absolutely flat for the lifetime of the board without some very small gaps between the straight edge and the board. Machined steel even has some tolerance in its flatness.

Im not trying to argue, Im just curious what tolarance is involved, because I think Im wasting a lot of time at home trying to achieve tolerances that I dont have to achieve. Examples: plywood (as stated above laid on a dining table) over its span is not going to be flat no matter what, an ironing board with something on top of it will also not be perfectly flat. Theres got to be perhaps a few thousands of an inch between the table and the straightedge. Maybe 1/4 to 1/2 mm millimeter. Im not saying these boards dont work, obviously they do, but on the flip side, obviously theres some point at which the boards are flat enough and minor variations dont make a difference. Im curious as to what is acceptable.

dicknadine

like WHO gives a DA--. forget all the yak-ity,yak-yak and get busy and build your models. this NOT a precision machine shop operation-- its a HOBBY. SHOW and TELL is the name of the game. Happy Flying. Dick

bash-ace-RCU

My Feedback: (16)

I have found that 2" milled ash has no equal when it comes to workbench tops. I have a piece that is 3'x5' and a piece that is 3'x6' that can be set up end to end and leveled (using a long piece of aluminum channel) for those rare large projects. The two combined are easily 200 lbs in weight (not really convenient for temporary workbenches). They can be purchased from any stanley vidmar retailer.

Heavy Date

I like glass for a work surface. Very flat, strong,and will last a lifetime. Mine is 4'X8' and 1/2" thick. It is tempered glass. I made a stand for it and checked for true using a flourecent light bulb, the 4 foot tube type. The margian for error on these tubes is +/- .001. That is close enough to perfect for just about anybody. In the 2 years it has been in my shop I have not had to adjust it once. Even I can't build a warp into a model on this table.
Hans