Vac table - base board ?

[dubliner]

Hey all - I can't find 3/4" 5x10 ply in Austin so I thought I could double up 4 5x5 1/2" sheets & glue them together. Would I need to seal those boards on all sides & how do I need to treat the seam in the middle to prepare for the vac zone board? tx Neville

[fleinbach]

Nevelle,

Is this for your plenum board or bleeder board. If it is your bleeder gluing them together will defeat your porpose. air will not pass through the glue. Personaly I woudn't glue 2 5'X 5' sheets togther unless you are vacuum bagging and even themn you will need a sturdy flat surface to pull them down to to prevent warpage.

I think I would look a little more for a suppier near you. There should be one.

[dubliner]

Frank, this is the sheet ( first sheet) that gets bolted to the table with the carriage bolts. I can not find anything in 3/4" 5x10 within a hundred miles. I probably will use MDF & T-track to make the
plenum as I cant get Trupan or light MDF either. But my main concern is getting the table fully bolted initially.

[dewey_dog]

Neville, I joined two 5X5 sheets together end to end on the machine I just sold and it worked very well. I did not glue anothe layer on top though so I would be careful about gluing a warp into the assembly as Frank said. When I glued the sheets together I milled a 1/4" grove into each edge and made a spline to fit,also make sure the joint is over a support channel. Hope this helps.

[beacon14]

I would try to stagger the joints - one layer use two 5x5 pieces, the other layer use one 5x5 piece, centered, and two 2 1/2 x 5 pieces, one at each end. Ideally you would vacuum laminate the two layers together.

[billp]

Neville,
If you REALLY want to make this bottom layer a tight, singular piece of material you could use Bill Young's "step scarf". This not only ensures that you'll have a solid connection, it also pretty much eliminates the possibility of any air leakage.
If you look at the following pix you can see how it's done;
Measure the thickness of your piece(s) and divide them into an "even" number of "steps". Using the 'Bot cut these steps in BOTH halves of your bottom layer. THEN just turn ONE board over and apply a liberal amount of adhesive to the steps. This gives a MUCH larger gluing area than conventional scarf joints, and it "locks"the boards into place, ( as you can see by the third picture...).In the following pix the material was .7" Trupan so I cut 6 steps, each being .1"lower than the previous one...Using this technique anyone could generate an "endless" piece of material...The only "downside"here is that you will lose the distance of the overlapping material, but you can plan for that in advance...
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[scottcox]

Neville,

Fine Lumber off of Dessau Rd. carries 5x10 sheets of 3/4" MDF. It's a bit expensive compared to 4x8 sheets. Here's their website for contact info.... http://www.finelumber.com/ .

Scott

[dubliner]

Talked to them this morning, they didnt have any 5 x 10 though.

[mikek]

Neville, I was looking for more 5' x 5' Russian Birch yesterday and asked at McCoy's why they didn't have any 3/4". They said the permafrost defrosted sooner than expected in Russia and they couldn't transport it until it froze back. I called Fine Lumber and Plywood and they had just ran out and had heard the same story. They will be getting more they thought however, and said to check back every two days. It goes quick and the price has increased 25% so far. Three sheets of 1/2" at McCoys was $97.39 with tax and the quality was getting marginal. Rough surface in places, but one side was OK mostly.