T track and vaccuum combination table

[beacon14]

I've been putting a lot of thought into the ideal (or more accurately, best compromise) table/holddown system, and I'm thinking about a combination of vaccuum zones and T-tracks. The T-tracks would offer a lot of flexibility for holding odd-shaped objects or using sideways-acting pneumatic clamps and simple fences to hold pre-cut panels for hole drilling, while the vaccuum system would have its well-known benefits.

My first thought was this:

4761

where the red represents T-tracks imbedded into the table and each open area is a vaccuum zone, but it seems to me the T-tracks on each end would be more usable if they were a few inches in from the end - but this complicates the vaccuum system. Also I think extending the T-track past the table edges would make it easy to clamp a fence at Y=0. So here's where my thinking is currently:

4762

A search of this forum on "t-track" yields surprisingly few results and none address this issue. So is anyone using anything like this, or just using T-tracks for general hold-downs? Any lessons learned or suggestions before I get in too deep would be much appreciated

[Brady Watson]

David,
One idea would be to do a full vac grid, place a 4X8 bleeder board on top and then a 3/4" X 4X8 sheet of plywood with t-track in it for non-vacuum-able parts. This would also allow you to screw into it. The only downside is that the vac needs to be on to pull it down tight.

-B

[don_roy]

I use T tracks often but I find that the design of the clamp is where the usefullness is.
I have clamps that have different reaches and my grid is in I foot square design. I have no vac system yet.
Don

[watswood]

David,
I use a t-track system with 2 different types of vac. The t-track does not open up to the edges of the table, but rather is part of the main vacuum grid itself. I leave about 1/2" extra space at each end of the t-track groove to get 1/4-20 bolts in and out of it. Most of the time I use part specific vacuum pods bolted to the t-track while using my air compressor/venturi high vacuum low volume pump. My other vac, a fein turbo II, uses the grid system for cutting sheet goods(something I rarely do). I typically leave a skin for sheet good cutting and then trim the parts out with a trim router. I try not to cut into the main table that has the t-track and vac grid. If I need to cut through I will suck down a sheet of 1/8" melamine(melamine side down) and double stick tape the sheet goods to the melamine. The melamine seals well and is a cheap and easy spoilboard.
If you need a y=0 fence you can rout a groove in your table so that the edge of the groove is at y=0 then screw/glue a narrow board into that groove.
Eugene

[ed_lang]

Does anyone who posted here have some pictures of what they are using?

I would like to "see" it.

[watswood]

Here are a couple photos of my 4x4 table. The t-tracks are gold and somewhat difficult to see. You will also see one of my custom vac pods bolted to the t-track.

4763

4764

[dvanr]

David,

I have seen one vacuum t-track type system on a mid iron machine here in Aus. I do not recall the name of the machine.

Basically it was either 1x3 or 2x4 steel box tubes as the table surface, the pieces were bolted or welded down and gaps between the tubes were large enough for a quarter or 5/16ths bolt. The tubes ran the length of the table and may have even been doubled up to 6 0r 8 inch wide sections. The steel box tubing was capped at each end to turn them into plenums and then they were plumbed with valves. I have no idea how many zones...sorry. Tops of the tubes were glued up with MDf and drilled with holes through to the tube.

It looked like a good idea , I now wish I had looked at it closer, as I have considered it. Just hesitate at the extra $500 for steel and assembly, resurfacing , plumbing......etc