I am about to cut my Plenum

[crash5050]

I am going to cut the 4x8 zone that comes in the SBParts folder, but this time I want to cut it before I glue the MDF down, to keep from having to take the chopping Ax to the machine again. So what I am planning is to countersink some drywall screws into the MDF about every 16 inches around the board to hold it to my birch table.

So now the question is where to put the screws.? The two questions I have are, can I take the Shopbot part file (sbp) backwards into aspire, or does anyone have the actual File that the 4x8 zone sbp file was created from?

What I want to do is layer the screws over the original part file, screw it down, cut it, pick it up, glues it and then put the screws back in when sealing it.

I have searched the forum, with no luck.

David

[curtiss]

I would think a good piece of MDF would lay pretty flat under it's own weight.

I would think screws every 16 inches around the perimeter would be more than enough. You might want to drill up from below and screw into the MDF from the bottom.

Has the wood below the plenum been surfaced ?

[crash5050]

I used the FC in SB3 to recreate the file, then i was able to locate where I could put my screws to hold it down before committing to the glue.

David

[adrianm]

If you look in the folder where you're loading the SBP file from (for example c:\sbparts\vacuumtables\96) you'll see a CRV (Partworks/Aspire/VCarve) file for the actual plenum design.

[jerry_stanek]

I ended up gluing the MDF to my sub base before I cut it. I was worried that there would be give between the two

[myxpykalix]

David,
I'm confused. What is your reasoning behind wanting to put a bunch of screws in the mdf into the plywood? I don't see a need to do that. When i set mine up initially i bolted my plywood to the table and countersunk the bolt heads in the plywood.

I cut my plenum in the plywood. Then i put glue on the face of my plenum and glue on the surface of my mdf and laid one on top the other.
I took clamps and cauls (2x4's) and clamped across the table about every 12 inches i think, and let it sit till it dried.

I then ran the table surfacing routine and was done.

If you put metal screws in your table, at some point YOU WILL run into them, its just a matter of time. I didn't see if you were putting a vacumn on this table?
If so, the screws going thru the bottom of the plywood will cause an air leak.
Also, a tip, if you do use a vacumn make sure to take silicone caulk and coat all 4 edges of the mdf to prevent air leakage from the sides.

[crash5050]

Jack 3 layers, table birch, bolted to the table. MDF plenum board screwed to table before I glue it, because crews come out if something messes up on the cut of the grid and the holes and such, glue is much les forgiving. after the MDF grid is cut, then I will glue it to the table, then add the trupan to the top.

[crash5050]

If you look in the folder where you're loading the SBP file from (for example c:\sbparts\vacuumtables\96) you'll see a CRV (Partworks/Aspire/VCarve) file for the actual plenum design.

I already owned aspire before I purchased the bot, I did not get partworks, so i didn't install, they are not there.

[adrianm]

They come as part of the SB3 software, nothing to do with the PartWorks installation.

It does look like they might have first been included with the beta version of SB3 though as that's what I'm running.