screen printing > DIY - From master engineered marvels to cobbled together jury-rigged or Jerry-built junk!
DIY exposure unit: any plans or advice appreciated
Wildcard:
Following on from one of my previous posts about my crusty old home made fluoro expo unit, I've been considering a fresh build rather than trying to renovate the current model. I'm hoping to tap into the knowledge bank of some of the DIY gurus here.
Basic requirements and factors:
- biggest frame size is 23.5"×31.5"
- floor space is under a staircase, in a corridor, so the vertical swing vacuum table with separate light unit won't work - it needs to be a table top. Vac top may not be able to open all the way up as a rigid frame because of the stairs above.
- mostly just shooting basic spot colour screens, but I'm playing with halftones more and more so I'm hoping for a real step-up from my box of fluoro's.
- emulsions: Kiwo poly plus SWR red (diazo), and also Ulano Orange (SBQ)
- high humidity climate and low to medium runs on screens. 99% plastisol inks.
Topics I'm looking for advice on:
- best light fixture options. Ive decided to move away from fluoros and get a point light source. I'm assuming the metal halides and LED floods available at the local hardware store or lighting shop are not good enough, so would the fixtures aimed at hydroponics be appropriate?
- vacuum blanket setup. Recommended type of unit and setup of the vac unit, and any fiddly things to consider. I've read some topics on the blanket and seems like a nylon lined neoprene is the go.
- general build advice. Anything that might be important to consider that is not common sense, ie. Air flow around lamps etc.
I hope there is enough back story here to paint the picture, and I would really appreciate any sound guidance. Thanks in advance.
James
Maxie:
I've built a few. Recently changed my table from fluorescents to LED.
For a light source contact Greg at Saati, they have a 300w LED that is great. Amazing for the price.
Just put it a little above a lean floor, it has fans in the back.
When you build the vacuum, make the glass bigger and have a rubber strip pushing up against the glass to give you a seal. I tried sealing against a metal frame and it kept leaking. The glass is always smooth and flat.
The lid can be made out of metal, I used 11/2 x 11/2. You can put the rubber blanket on the outside of the metal and connect the vacuum to the metal frame. Drill a few holes in the metal for the vacuum.
Most of the vacuum table suppliers will sell you a blanket.
Connect a nylon cord neat the hole and lay it over the screen so the vacuum works inside the screen.
Make sure you get clear hardened glass.
I have mine set up with two timers so that the vacuum works for a set time then the lamp switches on. They switch off together.
If anything isn't clear I can post photographs.
Wildcard:
Thanks for the info Maxie. I'm probably most curious to know what specs to look for in the vacuum pump and the lamp.
I've found a supplier for low iron glass, the box is simple enough to build, even the blanket doesn't worry me too much.
I've looked at some local hydroponic suppliers for a lamp and they have mh and led options that might work, and I'm intrigued to know if the big led floods at the hardware will be better than fluoro's. I'm not sure it will be good value to import a lamp or fixture from the US, but if it's the key that unlocks the secret door to good stencils then I'll consider it.
And of course photos would be great if it's easy but please don't go out of your way.
Homer:
wildcard, where are you located? I have a douthitt unit I will give you - search the ads here for pictures I posted up a hwile ago - , has integrator, excellent vacuum top, glass, the only thing is the bulb won't fire. drop in a new light source and you have a nice unit....pay freight, it's yours.
jvanick:
Wildcard... with how important good exposure is to the whole process, you should totally take Jay (homer) up on his offer.
For light sources, you want something that's strong in the 360nm (Pure Photopolymer) to 400nm (Diazo) range. Most LED lights are typically single or narrow-spectrum light sources, so trying to get a good exposure out of them unless specificialy made to emit UV light won't work too well).
MH grow lamps will definitely work better than FL tubes, if you can find something in the 1000w-3000w range, you'd be doing really good.
Remember to get an exposure calculator of some sort too, so you can optimize your exposure times after changing all these variables.
-J
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