How much vacuum do you get on a bare table?

[knight_toolworks]

how many " do you get on a 2x4 zone with no material on the table?

[harryball]

I get about 2.5" on the open zone.

/RB

[knight_toolworks]

I am getting about 4.5 to 5 just trying to see if I remembered right.

[harryball]

Has the back of your spoil board pulled away and plugged the opening? (like mdf splitting in half). I read your other posts, can't imagine what it is if the pipes are open and the vacs are working.

/RB

[knight_toolworks]

I have wondered that. I left at least 1/4" of spoilboard on when I added the 1" Plus I just checked and all 4 zones have the same " I had forgotten when I put the new top one I cut it into quarters. I screwed up one and had to cut another from another sheet. so that kind of rules out a bad sheet. what throws me off is that it was not there when I put the sheet on and took 2 weeks to show up. and it has gone and come back. it seems I have pretty good hold down though.

[gundog]

I get less than 1" with 2 lighthouse vacs running parallel with nothing on a 2'x4' zone. My spoilboard is Truepan my vacuum gauge is just a cheap automotive type 8" according to that gauge is all I ever get if I close all the valves.

I don't worry about the accuracy of my gauge it is just an indicator of vacuum and I know when I don't have enough to hold parts. I try to stay at 4"-5" more than that will overheat my vacuum motors so if I am not using the whole table I will crack open a valve to bleed some of the vacuum so that I stay at the 4"-5" level. I can hear the pitch of the vacuum motors and can tell by the pitch of the motors when they are flowing enough air to cool the motors.

Mike

[jerry_stanek]

You can not get glue the new spoil board dow to the old one without cutting new channels in.

[knight_toolworks]

well I shaved the top down to the original sheet of 3/4" ultralight I had on and that and worked for a month or more. by the time I had 1/6" or less left on I had lost only 2" over the top I had on it.
I do show about 1" or so of vacuum with no top on it at all. I just plugged the pipe and I get 6" with the pressure relief valve going. I set a surfaced one side sheet of ultralight mdf and I am back to the 5"
so I am starting to think I wasted my sheet for nothing. I have less pipe then when this began too though right after it did and I changed the piping I moved the gauge closer to the vacs.

[gundog]

Steve,
I believe it was Gary Campbell who posted that he uses a v bit to lightly engrave the outline of his plenum on the old spoilboard so you know where to put glue and where not to put glue then glue on the new spoilboard. That is what I plan to do when I replace mine, I am still working on my original spoilboard so I can't tell you first hand how well it works but Gary is pretty sharp so I think it will work good.

Mike

[garyc]

Steve...
Have you considered that the ULDF you are putting on just flows less than what you used to use? The porousity of ULDF can vary from batch to batch. Some brands flow very little. They (brands) are NOT created equal.

Also.. with no spoilboard on you should read zero vacuum, unless your gauge is close to the motor(s) and you have restrictions in the line.

[gundog]

Steve,
There is a place in Sherwood that carries Truepan Hardwood Industries is the place.

[knight_toolworks]

Thats what I was thinking too but it may be that the gauge is right on the t. it used to be next to the valves. But it is reading the same as it did when this started. I tore the pipe apart when it started and of course found nothing so I simplified the setup. elbow to check valve (I had a spring loaded one at first and I tested without any and it was the same)
to the t then a arc of flex pvc to a elbow and into the trunk. the truck as not changed for a long time.
what threw me off is nothing changed and then it did. removing the top did not change it
I won't be able to test the new top till monday after I surface it but I don[t think it will be super low.
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/cfec1ab6.jpg
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/f7b8ffe8.jpg
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/fc80fcb7.jpg
http://i154.photobucket.com/albums/s266/knighttoolworks/posting/79ffb107.jpg

[knight_toolworks]

Steve...
Have you considered that the ULDF you are putting on just flows less than what you used to use? The porousity of ULDF can vary from batch to batch. Some brands flow very little. They (brands) are NOT created equal.

Also.. with no spoilboard on you should read zero vacuum, unless your gauge is close to the motor(s) and you have restrictions in the line.
I have not heard of it. I just realized I only had one zone open so that's why it was not zero.
all I can really think of is low humidity causing the problem? my shop is pretty dry right now.
I thought this started right after I surfaced the table but it may have just started that day.
that's what has thrown me how it has come and gone. though I seem to have things staying in place as usual.