I'm picking up my metal halide bulb and ballast this week. What is an ideal size to build the unit to? I was thinking 24x36. Does anyone have any suggestions? Also I wanted to know how far away I should put the bulb away from the glass. Should it be 1.5 x the distance from corner to corner of the unit or just a standard 21 inches like Roger Jennings says in his video. Any help would be greatly appreciated. Thanks.
Re: What is a ideal home built exposure unit size?
that's about how big mine is. My bulb is about 40" from the center of the bulb to the glass. mines' not super nice, but i shoot screens anywhere from 50 sec. to 2.5 min., depending on mesh and mesh color.
RickB here on the forum made a niiiiiice homebuilt one. here's his link
Re: What is a ideal home built exposure unit size?
Thanks. I saw his. It looks great. I was thinking of making it 28x32 now. I think if the bulb was about 35in from the glass on that size I would be ok right? I am going to get supplies in the next half hour so any help would be greatly appreciated.
Re: What is a ideal home built exposure unit size?
I'm sure that'd be fine. i use 19x23 manual screens and the diagonal was like 28" or so, i don't remember. times that by 1.5 and i got 42", it was easier to build at 40" w/ what I had so i went with it and have had good results.
i didn't build the "funnel" coming off the bulb, either.
Re: What is a ideal home built exposure unit size?
Wow. I thought you had to build the funnel. I was actually going to but if I don't have to and can still burn good halftones i wont. I'm only using this in my little workshop that is for my own line of shirts. I wont be doing any contract work so it wont be used constantly. All i want is something that works and good burn good halftones.
Re: What is a ideal home built exposure unit size?
I guess ill try without the funnel for now. i can always incorporate that later. Just one more question. Did you also make a vacuum top for it or do you just stack some weight on top of the screen and did you incorporate a fan. Thanks for your help! I really appreciate it.
Last edited by sg613; February 23rd, 2008 at 10:12 AM.
Re: What is a ideal home built exposure unit size?
i have a really hokey, what i call a "jack-uum" top. there is a celing beam right above the table, i screwed a piece of wood to that, there's another piece clamped to that (it allows everything to give a little, so i don't break the glass). i have a scissor jack that presses against the wood with a piece of foam and plywood on the screen. i'd bet it's tighter than a vacuum.
i would like to build a vacuum top eventually.
i don't have a fan, since there is no funnel and it only has 3 sides, it vents out the back against the wall. it gets pretty warm in there.
Re: What is a ideal home built exposure unit size?
Ok. So i am practically done my unit. I cant find the right glass now! Is there a certain name for it? The guy told me I should be looking for something called non glare glass but I have no clue. All I told him is that I am looking for glass that doesn't have any coatings to block UV light from passing. Thanks.
Re: What is a ideal home built exposure unit size?
I've heard tempered glass will filter uv from the tempering process, but i use tempered w/o any problems. i just worry about the heat breaking non-tempered, but if you have a fan in there, i guess you'll be ok. i haven't heard anything about non-glare or anything.
Re: What is a ideal home built exposure unit size?
How did you get on with your exposure unit? Did it work okay and how were the results? I am trying to work out the best way to go about all of this.
Hopefully hear from you soon.
Re: What is a ideal home built exposure unit size?
This is my unit. Works like a champ, I use it with aquaSolv HV OVA emulsion. With a clear film I burn at 43 sec. With vellum I burn for 4 min
Got every thing from home depot. Here is were to find them........... Glass is a 24x43 (Doors), 4 18" Black light fixture kits $19 each NOTE: if there is a clear plastic cover over bulb remove it (Lights). 5 plugs power strip (Elc.), Alum. Foil.
What is a ideal home built exposure unit size? 
