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» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Using different diameter Carbon Rods, is it possible?

   
Author Topic: Using different diameter Carbon Rods, is it possible?
Ryan Plaisted
Film Handler

Posts: 8
From: Kittery, ME, USA
Registered: May 2004


 - posted 05-11-2004 11:39 AM      Profile for Ryan Plaisted   Email Ryan Plaisted   Send New Private Message       Edit/Delete Post 
This is my first post here, but there will be many, many more to come soon. I work at the Ioka Theater in Exeter, NH and recently the GM up and quit. And that leaves me all by myself. I've only worked there for a about two months and have had minimal training, so I'm going to have to be on a steep learning curve. Hopefully, you can help.

Okay, first question. We are using Ashcraft Suprex lamphouses which have a hole that fits 8mm positive rods (and nothing larger), which I am running out of. I have a case of 9mm rods that we have received by accident. The piece that holds the positive rod uses a bolt to hold it in and the bolt hole has been stripped (and retapped and then striped again, several times) and I was already thinking about just machining another piece (I talked to the people at Ed Wolk and they don't have the piece, but if anyone knows of a source for Suprex parts that would be useful, too.) If I was going to machine a part I would just make the hole fit 9mm rods as well.

So, my question is, Can Carbon Arc lamphouses burn any size carbon rods? Do the positive and negative rods have to be close in size (I have 7mm and 8mm negatives for some reason). What happens with larger rods: are they brighter or do they burn longer?

Okay, that's it for now.

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Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99


 - posted 05-11-2004 12:00 PM      Profile for Scott Norwood   Author's Homepage   Email Scott Norwood   Send New Private Message       Edit/Delete Post 
Different diameters are for different amperages. You'll have to check the current rating for the 7mm negative and 9mm positive, as well as the capacity of your rectifiers.

New carbons (including 7mm/8mm, which is quite common) are available from Marble. You might be able to trade the 9mm carbons with another theatre, as the larger sizes are usually more expensive.

BTW, _please_ send in pictures. The Ioka is a great theatre.

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Pete Lawrence
Expert Film Handler

Posts: 192
From: Middleburg, PA
Registered: Aug 1999


 - posted 05-11-2004 02:57 PM      Profile for Pete Lawrence   Email Pete Lawrence   Send New Private Message       Edit/Delete Post 
Here are a couple links with sizes and amperage ratings. I have no idea as to the quality of their products.
cinemacarbons.com
Marble Double Eagle

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Steve Kraus
Film God

Posts: 4094
From: Chicago, IL, USA
Registered: May 2000


 - posted 05-11-2004 07:06 PM      Profile for Steve Kraus     Send New Private Message       Edit/Delete Post 
Bravo to anyone running carbon.

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Jack Ondracek
Film God

Posts: 2348
From: Port Orchard, WA, USA
Registered: Oct 2002


 - posted 05-11-2004 09:48 PM      Profile for Jack Ondracek   Author's Homepage   Email Jack Ondracek   Send New Private Message       Edit/Delete Post 
Even if you can do this physically, and assuming you can burn a proper crater into the positive with the amperage you use now, you'll have to readjust the negative feed to keep the trim in place. That may not be possible, if it's outside of the design parameters of the lamphouse.

I never had good luck with the Marble carbons, but that may have changed over the years. The best service I was able to get out of them was when I kept them in a broken-down refrigerator with a light bulb in it to burn off the moisture.

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Ryan Plaisted
Film Handler

Posts: 8
From: Kittery, ME, USA
Registered: May 2004


 - posted 05-12-2004 11:48 AM      Profile for Ryan Plaisted   Email Ryan Plaisted   Send New Private Message       Edit/Delete Post 
Alright, in that case I'll forgo the experiment and get some 8mm.

Thanks for the supplier links. We have the Marble DE's now and I've never had a problem with the exception that if I keep rods "on deck" in the lamphouse for too long they get warped and won't fit.

I'll try to get pictures up in the next few weeks.

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 05-12-2004 04:28 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
quote: Jack Ondracek

I kept them in a broken-down refrigerator with a light bulb in it to burn off the moisture.

Would something like a welding oven used to heat welding rods/electrodes before use be handy to have in a carbon house?

Yeah, at $800.00 it's not cheap but (A) it could save you at lot of trouble (less trouble = less money lost) and (B) I'm sure there are smaller, less expensive models out there that do the same thing.

...Just a thought.

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 05-12-2004 06:13 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
All one has to do is put a couple of trims inside the lamphouse a day ahead of time and they will be ready to go

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Jack Ondracek
Film God

Posts: 2348
From: Port Orchard, WA, USA
Registered: Oct 2002


 - posted 05-12-2004 06:44 PM      Profile for Jack Ondracek   Author's Homepage   Email Jack Ondracek   Send New Private Message       Edit/Delete Post 
yah... we did that, too... but we had to brute-force the early Marbles, and the refrigerator method did as much as anything.

None of that was required with Nationals [Frown]

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Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99


 - posted 05-12-2004 06:49 PM      Profile for Gordon McLeod   Email Gordon McLeod   Send New Private Message       Edit/Delete Post 
The only carbon I used to dislike was the Ibagwa line called Sunny Carbons also the Diamond carbons sorta sucked too

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