[sledzeppelin]

I'm about to build myself an exposure unit but I'm not sure which 1000 watt MH bulb to get. They range in price from $20 (on 1000bulbs.com and ebay) to more like $60-$120 for "grow lights" and up over $2000 from various higher end screen printing supply places.

I don't need my exposure times to be lightning fast, so do I need to spend $100 or can I get one such as this:

TCP 46370 | 1000W Metal Halide Bulb | MH1000W/U

I don't mind spending more money for quality, but if $20 will get the job done, I'll go for that.

 

[outbreak]

I burn a screen in 7 minutes with 2 of these.

http://thd.co/11QQGgl

 

[foot print]

Exposure times will vary with type of emulsion and type of bulb and a few other things.. I built my exposure unit. Started with 400w exposer times was 1min 50sec switched to 1000w metal halide grow light now I burn screen in 25 sec.


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[sledzeppelin]

Foot Print, do you have any experience with a non-grow-light 1000w MH? I'm wondering how much difference that makes. Do you know which particular grow light bulb you have?

 

[foot print]

I know my bulb was not a expensive one.. I got 2 bulbs and a ballast for $75 on Craigslist. I have used a non grow light 1000w MH and times are the same..


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[Hoghead1]

On Ebay you will find MH grow lights systems. Most use the bulb type you showed. I bought mine for around $200 and included the bulb, stat/starter, wiring and reflector. Ready to plug into a wall socket. I burn screens in about 1.5 minutes. I think these systems are made for the Colorado gang.

 

[gmba]

f

I burn a screen in 7 minutes with 2 of these.

Voltec 500-Watt Halogen Portable Work Light-08-00209 at The Home Depot

outbreak, what is your distance if you don't mind me asking, I'm in an area where metal halide bulbs are hard to come by so I can deal with 7 minutes. I'm using Ulano QTX. If I get two of those 500w, what distance should I start out with.

 

[sben763]

What Makes the difference is the actual light spectrum That the lights put out. The closer to 365nm-395nm(for photo polymer) or 395nm-420nm (for Diazo dual cure). Most the Grow light systems are for flowering which those bulbs peak around 600+nm

here is the bulb I use. USHIO MHL 1000/1 Blacklight Metal Halide bulb - 5000062 for $36.00 They sell the sockets there also. I bought a grow kit off ebay with digital ballast and switched out the bulb and socket.

the specs on the bulb show 1200 watt but at 135V. at 120V its 1000watt

 

[gmba]

What Makes the difference is the actual light spectrum That the lights put out. The closer to 365nm-395nm(for photo polymer) or 395nm-420nm (for Diazo dual cure). Most the Grow light systems are for flowering which those bulbs peak around 600+nm

here is the bulb I use. USHIO MHL 1000/1 Blacklight Metal Halide bulb - 5000062 for $36.00 They sell the sockets there also. I bought a grow kit off ebay with digital ballast and switched out the bulb and socket.

the specs on the bulb show 1200 watt but at 135V. at 120V its 1000watt

How can you tell what spectrum the light puts out? After looking it up, Ulano QTX states it's a photo polymer. I can order a metal halide, but I'm looking to get a job done by this weekend. The only thing I have access to is halogen.

 

[sben763]

you can use a halogen Just will take much longer. The good bulbs have been tested and are stricter manufacture tolerances. You can buy 2 bulbs of the general purpose metal halide and one will take say 4:00 and another 8:00 of the same bulb.

If you look on that website there is a spec sheet for the bulb. A lot of the grow bulbs have a spec sheet. the grow bulbs that are for starting and finishing will usually have the lower white/blue spectrum needed for proper exposure

 

[sledzeppelin]

here is the bulb I use. USHIO MHL 1000/1 Blacklight Metal Halide bulb - 5000062 for $36.00 They sell the sockets there also.

Is this the right socket?

Ushio Double Ended R7s / RX7s Ceramic Socket Lamp Holder 10A 250V 5in Lead - 1000117 for $7.50

 

[sben763]

Yes but I bought the one with the 8" leads and it was almost too short. Due to the heat make sure to use porcelain wire nuts and the wires getting connected either have to be high temp or in a junction box a min of 6in from the bulb. I have a 6" fan fan with intake air for cooling and my my connections are on the intake side.

In the screen print equipment section I have my project posted. It's not a total DIY project as the cabinet was a old National exposure unit with halogen and blacklight I converted and made a manual shutter. I didn't want to build anything out of wood as I have seen these lights catch fire on post.

 

[LostboyTNT]

distance makes a world of difference too, I'm using a pair of 2000w Halide bulbs I picked up (for about $25 each) and made into a homemade setup (running it off of 240v,2phase because of the power draw) but even with 4000w, because I have about a 3.5' distance my exposure time (varies with mesh, and emulsion) is around 3 minutes.

Once you're set up, make sure you do a steptest with various halftones and sharp edges to find your optimal burn time.

 

[sben763]

(running it off of 240v,2phase because of the power draw) .

What's 2 phase. Been a electrician over 20 years and don't know that is. I know single phase and 3 phase. Also 4000watts at 240v is 16.7 amps for single phase and 11.1 amps on 3 phase.

Your distance changes times but so does the correct spectrum. If your bulbs are only putting out a factor of .25 and the 365-420nm spectrum then your only getting the same amount of UV I am with 1000watt and a factor of 1.0. With dual cure I expose 2.0-2.5 min depending on mesh and 45 sec - 1:30 with photo polymer. I would guess my bulb is 30"-36" to glass. I just mounted in the bottom and now I wish I had mounted at 24" as on a test before build I was at 25 sec max at that height.

****edit. I found out 2 phase was last installed in 1895. There is block of buildings in Philadelphia PA that are the only 2 phase power left today.

 

[sledzeppelin]

Thanks for the info about the wire nuts. I wouldn't have thought of that. I ordered a step wedge today.

I've been planning this out in my head for about a week now and I think I have a design pretty well worked out. We have a great local dump here where you're free to take stuff from the scrap metal, so I'm going to try to grab some old grills (there are always several of them there) and use the sheet aluminum from them, and I think I have a pretty clever shutter mechanism in mind.

I also got a big old window with 1/4" panes I'm going to cut down. A friend works at an engineering school and he can cut it for me on a water jet. I already cut an 11x17 piece (score and snap method) which I'm going to test this weekend exposing on my halogen to see if it increases the exposure time much. I'm hoping since it's old it doesn't have much UV protection.

 

[LostboyTNT]

2 phase, 3 phase, whatever.. lol, I'm no electrician, I had my buddy with the electrical engineering degree to help me out with the wiring.. basicly I split the 240 into 2 120 lines.. and it works. (with proper cooling)

I hear a lot of people "ordering" step sheets, my opinion is, print one yourself, that way you have the proper transparency opacity for what you're going to be using on a regular basis.

also, be careful about using certain glass, (especially certain types of window glass) a lot of it actually has UV blocking properties, which will substantially increase your exposure time. since it's in the UV range that is needed for exposure.

 

[sledzeppelin]

Yeah if this glass increases my exposure time using my 500w halogen, I'll be ordering some different glass.

 

[sben763]

Here is a indication how much UV will be cut. Look at the edge of the glass. The more green the more iron the glass contains.

If you have to go purchase glass ask for star fire glass. Its the lowest iron most optically clear glass.

 

[outbreak]

Re: f

outbreak, what is your distance if you don't mind me asking, I'm in an area where metal halide bulbs are hard to come by so I can deal with 7 minutes. I'm using Ulano QTX. If I get two of those 500w, what distance should I start out with.

Sorry for the delay, mine is 18".

 

[gmba]

Thanks, I went ahead and ordered a 1000w metal halide with bat wing setup. Ballast and all ran me about $150. Should be able to pick it up Monday.