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Author Topic: Carbon Arc (Cinema carbons Vs Gouging electrodes) Henry Titchen Film Handler Posts: 31 From: Singleton, NSW, Australia Registered: May 2005 posted 11-01-2005 05:52 AM                     Hi, I recently came across a metal working workshop where Carbon arc electrodes were used for a process called "gouging". The copper coated carbon electrodes look identical to cinema carbons. Upon enquiry I found that the price is very cheap. (Around $15 for 100 electrodes). Does anyone here know the difference between the two types of electrodes? Can gouging electrodes be used in projection gear safely? Thanks From, Henry.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-01-2005 08:24 AM                     Yes have heard of it before but I don't know of any shops using it around here. There is also what is called EDM (Electrical Metal Disentegration) that is a very precise machine capable of very high tolerances..... as close as 1 micron. I think you will find that water jet custing is replacing what you saw. Water jet uses 60,000 psi water jet to cut metal up to 6" thick. We just had a batch of Christie negative lamp supports roughed out this way then I just finish drilled and tapped the required holes. These negative lamp supports for the older CH series lamps are NLA from Christie and our cost per unit was about 1/3 of our old cost of the factory part from Christie. Because of the odd shape of this part it coldn't really be done by hand on a mill. As for using them in projection I would doubt that the core of the carbons is treated with the correct rare earth elements and they would more than likely not burn very consistantly. Mark  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 11-01-2005 08:42 AM                     quote: Mark Gulbrandsen As for using them in projection I would doubt that the core of the carbons is treated with the correct rare earth elements and they would more than likely not burn very consistantly. I tried it once; I found that the arc was unstable, and the spectural composition of the light was wrong, and not as bright. You might just get away with using them as negatives in a H.I. arc, but not as positives. Sadly, I think the end really is here for projection arcs.  |  IP: Logged Joshua Waaland Jedi Master Film Handler Posts: 800 From: Cleveland, Ohio Registered: Dec 1999 posted 11-01-2005 08:27 PM                     quote: Mark Gulbrandsen I think you will find that water jet custing is replacing what you saw. Actually Mark, gouging rods are mainly used to back gouge a weld on steel plates. It removes metal and creates a valley that can be re-welded. The company I work for makes carbon gouging rods and I think I brought this topic up before though I can't find the old thread.....must have been on the other forum I guess. Anyhow, the ones we make are hollow which is supposed to cut down on smoke and give a better gouge. Henry, we have a branch of our company down in Queensland Australia and I am sure that he would send you some samples if you request them. His name is Brian. Below is the info. Anyone stateside who wants to try these can e-mail me and I can send them some samples and you can enlighten us all on their performance in a lamphouse. Hope this helps. Phone: 61 (0) 7 5496-9555 (9599) [ 03-13-2009, 07:53 PM: Message edited by: Joshua Waaland ]  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 11-01-2005 10:33 PM                     So Josh, Is this company you work for in the old National Carbon building or anywhere near it? I was aware of gouging but have never seen it done. I probably don't have things welded that are so thick as to require that. Mark  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 11-02-2005 01:09 AM                     I doubt your powersupply will be able to regulate them as the voltge drop across the arc vs the current is very different Also if you were familiar with how a re carbon arc works the light is from the sublimation of the rare earths in the core being volitzed in the positive crater none of which are found in welding carbons  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 11-02-2005 03:47 AM                     My experience was that a very shallow, irregular, crater formed in the positive; a stable arc would burn for a few seconds once this formed, but would then wander around the tip of the positive at random for a while, before briefly stabilising again. Even when the arc was stable, light output was very poor. The carbons did have some sort of core, but goodness knows what was in them; certainly not like projection carbons, which I think use Cerium salts in the core of the positive. I believe that welding, brazing, gouging etc. arcs normally run on a.c., and use a pair of similar carbons. I didn't try using one of these carbons as a negative, with a proper positive; I suspect this might have a greater chance of working, but I don't know for sure. They are hopeless as positives. They might possibly work in the old low intensity, vertical, arcs, like the ones used in Brenographs, and some old spots, but I haven't tried it, and I think it's highly unlikely that anybody is still projecting film with those type of lamps today. The only film projectors I've seen with them have been hand-cranked silent machines, in museums.  |  IP: Logged Joshua Waaland Jedi Master Film Handler Posts: 800 From: Cleveland, Ohio Registered: Dec 1999 posted 11-02-2005 09:50 PM                     Mark, quote: Mark Gulbrandsen Is this company you work for in the old National Carbon building or anywhere near it? No, we are in a small strip building. All of our stuff is made at our headquarters in Newmarket Ontario in Canada, except the carbons and ceramic weld backing which are made at our location in China. quote: Mark Gulbrandsen I was aware of gouging but have never seen it done. I probably don't have things welded that are so thick as to require that. I have only seen it done once or twice myself. It is obnoxiously loud and dirty. Once the arc from the carbon turns the steel molten, the gouging machine blows compressed air into the puddle which then sprays the molten steel in all directions. It leaves a very nice valley though once it is done. I once got to go on a equipment demonstration with my boss to a local company that made huge (20' diameter) steel fans for ventilation. There was a guy that was back gouging and I went over to watch him. I can send you a video of our equipment with a back gouger attached to it that we recorded in our warehouse. It is on our cd catalog but I don't have one here. I will e-mail it from work tomorrow if it's not too large. That goes for anyone who wants to see it. I will also try to post a picture of a plate we back-gouged on here. [ 11-03-2005, 01:37 PM: Message edited by: Joshua Waaland ]  |  IP: Logged Joshua Waaland Jedi Master Film Handler Posts: 800 From: Cleveland, Ohio Registered: Dec 1999 posted 11-03-2005 08:20 AM                     Here is a picture of a sample plate that we did some gouging tests on.  |  IP: Logged Jim Spohn Film Handler Posts: 95 From: Bakersfield, CA, USA Registered: Jan 2003 posted 11-03-2005 09:14 AM                     Our theatre is a Carbon Arc exclusively house. We tried the gouging rods in several applications and found them to be 100% wrong for projection. The arc is not steady, uniform or of the correct Kelvin temperature. If you don't stand next to the lamp and baby-sit the arc will go out. Nice try but no cigar. Jim  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 11-03-2005 09:31 AM                     Nice to hear that someone still uses carbon arc! Indeed i still have couple of boxes in mine desk, maybee someone will need them someday! Many projectionicst don't have experiance with carbon arc. Well i do some projection with carbon arc couple years ago, one of that cinema is closed now :-( and other I repaired to xenon lamp. Is there any carbon arc still producting?? I remember here were used germans carbon arc's i don't remember producters name but i'm sure that where markings positiv on + electrode and nunega on - electrode. Before couple of years when couple of cinemas used them what i know is been so hard to find it and price was very high because they be out of produce for long time now. Funny thing was that some projectionics do hear like mine father is that after show arc's where small, but not small do not do one changeover for about 30-40minutes, and there was some holders so you can use whole electode, because normal you can't use last 10cm of lectode on some carbon arc houses. But i know that some people used carbon arcs for gouging.  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 11-03-2005 12:06 PM                        Carbons are still available. Some company in India ("Schultz Carbon Electrodes"?) is manufacturing carbons under the National brand. Marble in Japan is producing much better carbons under the Eagle brand. There may be other manufacturers as well. For those who need lamphouse parts and such, I know that Lenny Miller of Eastern Cinema Supply has a reasonable stock of assorted parts. There may be other sources as well.  |  IP: Logged Joshua Waaland Jedi Master Film Handler Posts: 800 From: Cleveland, Ohio Registered: Dec 1999 posted 11-03-2005 01:39 PM                     I found a company on the internet a while back that still makes them. I have the link saved on my computer at home. Will edit this post later with it as long as the link still works.  |  IP: Logged Henry Titchen Film Handler Posts: 31 From: Singleton, NSW, Australia Registered: May 2005 posted 11-04-2005 04:03 AM                     Thanks for all the useful info about gouging carbons. I guess it would have been too good to be true if they were to work as well as a genuine "cinema carbon". Can anyone recommend a source of carbon rods in Australia? Thanks From, Henry.  |  IP: Logged Marin Zorica Jedi Master Film Handler Posts: 671 From: Biograd na Moru, Croatia Registered: May 2003 posted 11-04-2005 06:12 AM                     There's some link of one carbon arcs producter : http://www.lithcoproducts.com/prods/carbon_arcs.htm It says that are high intesivity carbon arc's, so this can do well on projection, what do you think?  |  IP: Logged

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