[DHay13]

Designed and built my vacuum table using (2) 3/4" sheets of MDF. Cut all pockets, grooves, grid, etc., and put about 4 coats of shellac on it. My grid is closer to about .237 wide by .200 deep. I am using .250 EDPM closed cell cord from McMaster Carr. When I put it in the grid it always leaks right at the joint. I turn both ends to the left (one left and the other right as you are looking at them) so they pass by each other at the same intersection. I also put a little twist in the cord at each bend to help keep it from lifting. I am using the Thomas pump kit from Joe Woodworker. I get to about 25" of mercury but it slowly drops. I can hear where it leaks from and have moved the cord so the joint is at different locations and it always leaks where the joint is at.

Ideas/suggestions?

[ger21]

How about a picture? Are you sure it's leaking at the joint? Is the joint tight together? Try using a longer cord and force it into the groove so that the joint is very tight. You can also try to glue the joint with ca glue.

How are you getting to 25" Hg if it's leaking?

[gbradley]

Try using a square gasket instead of cord. Is your channel square? if so I would keep the channel with the same but go to .25 and get All Star Adhesives U MG 25 312 Medium Density or the Firm Density U IR 25 312 depending on what you are cutting. You can contact me if you have any questions [email protected]