What is the best On/Off switch setup for a vacuum table?
I've been scheming lately on how to create my own 3'x4' vacuum table largely using AndyMacs plans, albeit slightly modified. The part that has me stumped is what would be the best way to create the switch that would turn the vacuum on and off.
I've considered a few things based on all comments on here. One would be some sort of foot-pedal (seen here: McMaster) or a hand-switch, possibly a mounted surge-protector. It seems like this would be the most convenient, but some people have raised the possibility that this may prematurely wear out the vacuum motor.
With that stress factor of constant ons-and-offs in mind, I thought about something like this that we have in our school printshop at MCAD – link, and detail here. The vacuum stays on constantly, and then you just move the lever whenever you want it to engage.
What am I missing? Are there any devices that I should look into? High volume production doesn't frequently happen, with most jobs being around 60 or so, and 250 on the high end if that changes anything.
I remember seeing pictures of a DIY build somewhere, similar to Andy's plans I'm sure, but as well as having the pipe from the vac going in on the one side, there was a similar pipe going out on the opposite side that could be closed off with a small racquetball or similar. Same idea to the lever on your school's unit probably; the vacuum stays on but it's only holding the paper down through the top when the big intake pipe is closed off. And it would be within arm's reach on the side of the table so you wouldn't have to be constantly bending down.
I'm not sure how well it works, but it seems logical to me, and it's a pretty simple solution to the on-off problem.
Also, I feel like I saw somewhere that someone had incorporated a rocker switch from a surge-protector into the table itself, and placed it right near the fulcrum point of the screen so that when the screen was up, the switch was off, and when the screen was down the vacuum was on. Thinking about it though it seems like this setup would leave very little room to register your screen. Am I crazy or is that a bad idea?
Last edited by bwiley; 06-12-2012 at 06:08 PM.
Reason: edited for spelling
Thanks for weighing in, Andy. I think I'm going the foot pedal route for simplicity, although I have to say I wouldn't mind figuring out a way to incorporating a switch like you did on the Jaguar. I can see how you'd do it with an articulated hinge like that, but I can't think of how you'd do it off of a setup that utilizes speedball clamps and still afford any movement of the screen for manual registration.
The reason why I'm so curious is that I'm setting up a screen printing lab for a non-profit art center in Upper Minnesota, and I want to make sure it's the best possible flat-stock lab I can give them. The goal I suppose is $100 a station in materials, which I feel is do-able, but I definitely don't want to skimp. I'm always so tired of going into public labs and things like registration and off-contact aren't being dealt with. For instance, at MCAD where I went to school, they don't even have the speedball clamps level with the table. Obviously that's an easy fix, but I just don't want to saddle this new lab with something they're going to out-grow as people get better, and I don't want to set up the lab so that it will frustrate new printers and discourage them from trying it again. Any additional tips would be greatly appreciated.
You won't make a decent 3x4' table for 100. Also, you will never make screens that big/people won't print that big. I had a 3x4' Jag for years, and I think I ran 3 or 4 jobs that size in 10 years.
The most usable/easiest is to build setups that will handle 23x31 screens (good for 13x19 images/film size) or 25x36 screens which will allow for larger prints. Most people can't hand print bigger than that. that 24x36 Rabbit design will take both.
You can build 3 tables from 2 sheets of 5/8 ply. Hit up a cabinet shop for offcut laminate cheap. You should be able to meet your $100 budget if you skip the copper counterwieght bars. We build a set of eight for a classroom a few years back, got the students to do all the glueing screwing and drilling. they loved it, and learned how to make their own print gear.
I used a one arm from some company years ago that had a U clamp with a spring activated microswitch on it. You clamped the thing on the side of the frame near the back and when it came down, it contacted the table and turned the vac on. An industrial electricial supply would have that, but it then needs to be wired in. That cheap footpedal is the best, and allows you to turn on the vac after you place the piece, but before the head comes down. We have an override switch for this function on the Jags, and our Nano Prints have this in the foot switch (You just keep your foot down. when you release the pedal, the print stroke starts. Very good for wavey stocks, or things that might shift while waiting for the vac to kick on if it is actuated by up/down movement.)
You're right about the size – I meant 24x36. I too had a 3x4, but unlike you never ran a job that big in two years. So the size is set.
So is the foot pedal thing, at least as far as it being a foot pedal to activate the vacuum. I still need to decide where to place the vacuum flange. I'm leaning towards underneath the table, but that may make it difficult to just set these things on pre-existing tables.
I'll keep you posted on how the build goes and put a set of photos and CNC plans up for anyone that wants them when I'm done. Thanks again for all the advice!