Triac Vacuum Table

[Matt]

I thought some of you might find this of interest.

90 percent of what I do with my Triac is cutting parts from acrylic sheet (Perspex). Normally they're quite small and intricate so I have a piece of MDF on the table and tape the plastic on top with double sided tape. When I cut the part I leave 0.1mm so it stays in the sheet and doesn't move. Then just break them out. This works well but messing about with the tape can be a bit of a pain, especially for long runs of the same component.

So I had a go at making a vacuum table out of some spare 5mm acrylic sheet I have.

As you can see in the pictures, its basically three pieces 330x175mm. One piece is drilled with 920 holes 2mm diameter spaced every 7mm. One piece is cut out to a depth of 4mm to provide the void for the vacuum. The third piece is just to beef up the underside.

I then bonded the pieces together on top of something flat. Then added a 10mm strip to sit in the slots of the table and stuck on the flanges for bolts. I then surfaced the whole thing with a large router bit.

I already have a vacuum pump I use around the workshop, which I connected with plastic pipe.

The table works well. All the time you have a good seal its amazingly strong, you cannot move the material at all when the pump is running. The only problem I had is when using a tool larger then 2.5mm it has a tendency to pull the 0.1mm I leave into the holes. Where the cutting tool warms the plastic it's thermo-formed in to the hole. When you lift the material off it has small pimples on the back along the tool path. This wouldn't be a problem but sometimes they brake through and you loose vacuum and therefore hold.

I have now made another table with 2840 1mm holes spaced every 4mm. Seems much better and the pimples are no longer a problem unless I go very thin. I may make another one day with 0.5mm holes.

It's too early to say how much it will replace the double sided tape. It gets annoying having the pump running all day, and you do have to cover up the holes your not using, but it didn't cost me anything and it will be a useful addition to the workshop.

[Steve]

Looks good.

How have you created the Vacuum?

We have some adaptors that plug into a standard vacuum cleaner hose that allow air to pass through the vacuum so cooling it but also creating a vacuum on a smaller diameter pipe.

We have sold these for about £5 on our Ebay store. If anyone is interested we can post some more of them.

[Matt]

I'm using a "proper" vacuum pump that I use for casting resin and laminating wood. The type of thing you find in a vac-forming machine, an electric motor with compressor pump on the end.

I hadn't thought of using a vacuum cleaner. It may work better? I think my table would need redesigning to allow the greater volume of the vacuum cleaner to get through because it would have less pressure. It would probably be more forgiving if you had small leak around one of the holes, but I don't think it would hold as tight as the pump. It takes a moment or two to remove the air, then you can hear the pump change tone and its got it! You could put it against a wall and stand on it..........Just tried it on a door and takes my weight easy!

[Denford Admin]

Looks really nice !

Do you have any problems with the Acrylic cracking when its bolted down ?
If not - what type is it / where did you get it ?