I'm planing on building a vacuum table. I've already bought Andy's book, so I'm solid on how to build the actual table but I've been looking at how to incorporate registration into it if I can. From what I've gathered, there are a couple different ways to do this. One is a floating table within a fixed frame using some method to push the table around (like with screws) to achieve registration. The other is to mount the table on top of some mechanism which can then be adjusted to get everything registered.
It's on this second method that I'm a little foggy on the specifics. I was watching this video in which he seems to be using this means of registration but I can't tell what is going on under his vacuum table. Can anyone describe how this type of registration works?
go to Squeegeeville Facebook page and look through the photo albums, there are a few newer better photos of how the Rabbit table goes together. In this, the backbar, which holds the frame and the counterweight, can be loosened (the 2 black knobs) and the whole thing slides around to alighn with the print. Then lock it down again.
This is rudementary register, and always a problem because the screen is flexing when printing, or moves a bit when locking. The way you are talking where the table moves, is typical on many auto presses - you unlock the top, then use the dials to move the table slightly. This is a better way, because the screen stays locked in position. But, you need to make the table 'floating' with locks and make it so it doesn't move when tightening the locks....a good trick, even on expensive tables.
What most people do (on the Rabbit or even bigger auto tables) is to move your register guides - pull a print, check the movement needed, move the tabs, print and check again. Go until it is in register, then lock you tabs, table and clamps so nothing moves agian during the run.
The biggest issue with registration is putting the paper into the tabs accurately. Many don't do this simple thing. Gotta go, good luck
I understand how the back bar works. Not too dissimilar from using jiffy clamps if that's the only method of registering you're using. What I do now is like you described and move my registration tabs around until I know everything is lined up like I want it.
In the video I linked above though, it looks like he has registration built into the vacuum table itself. The 3 handles with the big red knobs look to be some form of registration, and that's kind of what I'm curious about. At 5:45 in the video, he is registering his screen to the print and twists the knob at the end of the table instead of adjusting his tabs. Please someone correct me if I'm wrong and that's not what he's doing.
I have an idea of how this might work, but I thought I'd go ahead and ask some people with more experience if they might know.
Again, thanks for any light anyone might be able to shed.
You shouldn't bother with a movable registration built into the table or hinges. Just move your tabs it's pretty easy to do and always works.
Yes that's what he's doing in the vid. The knobs connect to threaded rods that pull/push the table. One knob does left/right. Another does left side forward/back and the other right side forward/back. If you are building this then you need to know that the bed has to ride on frictionless pads or the whole operation will be fubar. The larger the threads on your rods the better as well.