my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » HELP! Century SA & Simplex SH-1000 Running At Different Speeds! (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: HELP! Century SA & Simplex SH-1000 Running At Different Speeds! Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-03-2006 08:44 PM                        Resident Experts... I recently mounted my Century SA head on a Simplex SH-1000 soundhead. Both units were throughly renovated by the entities that I purchased them from. The problem is that the soundhead gearing appears to be running on-speed at 24fps, but the picturehead is running somewhere under 20fps (I know this because the fire shudder does not open on it's own). I have checked the weights on the vertical shaft, and the shudder WILL open if pressure is placed on the lever, but it will not under normal operation. I have ascertained that I do have the correct 3.25" fibre meshing gear for these two models. At this point in time, the supplier of each head has not been able to sleuth out this issue. Does anybody here have any idea how to proceed to troubleshoot this problem? Any and all help will be appreciated. Brett  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 04-03-2006 08:58 PM                       Have you run film through the projector and soundhead? If the two are running at different speeds, film will either break or accumulate somewhere between the projector and soundhead.  |  IP: Logged Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-03-2006 09:57 PM                        Sam: As you suspected, the film pulls tight and tears sprocket holes between the last sprocket in the picturehead and the first sprocket in the soundhead. I know for a fact that the soundhead is running faster than the picturehead. I did a little experiment, I put a pencil mark at the 12 o'clock position on the bottom sprocket in the picturehead and on the top sprocket in the soundhead. Then I hand-turned the soundhead motor and rotated the soundhead sprocket ONE FULL clockwise revolution, and then found that the mark on the corresponding picturehead sprocket only moved to the 4 o'clock position. This indicates that the picturehead is running at 8fps, exactly 1/3 the speed of the soundhead running at 24 fps. B.  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 04-03-2006 10:06 PM                     check all the fiber gears in the projector head for any missing teeth. Also check to see if the main drive fiber gear at the bottom of the projector head is meshing with the steel gear correctly at the bottom of the vertical shaft in the projector head. Lastly, check the fiber gear that mounts between the projector and soundhead for the correct number of teeth. Had one once that was wrong. Projector ran at different speed like yours is doing..  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 04-03-2006 10:28 PM                     The soundhead gear turns once every four frames. It has 16 tooth film sprockets and the drive gear is on a sprocket shaft. I'm pretty certain that the projector main shaft is one turn = one frame. So the projector drive gear must turn 4 times the speed of the soundhead output gear. And the projector gear needs 1/4 as many teeth as the soundhead gear. However - the only gear drive sets I know of are the same ratio, they might be different sizes but they differ in tooth pitch and angle. I don't know if you could get a mixed up pair to work at all. Anyway, count the teeth and see if they are 4:1. There are composite drive gears with a rubber shock-absorbing ring between a hub and a toothed ring. These are famous for slipping when the rubber breaks loose from the hub or toothed ring; the teeth can turn without turning the hub. This causes snapping film on startup or even a slow running projector depending on how bad the gear is and the projector drag. If you have these composite gears replace them. They haven't been made for decades so the rubber is hard by now even if "new old stock"; get new solid gears.  |  IP: Logged Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-03-2006 10:48 PM                        Here is a picture of the fiber meshing gear I am currently using:  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 04-03-2006 11:43 PM                     Being a SH-1000 (4-star) soundhead, wonder if the upper brass gear, that is attached to the upper holdback sprocket, in the soundhead transmisson has gone bad..due to lack of lubrication..causing gear jump for that upper holdback and causing the film to have the sudden tension problems between head and soundhead... Then, I forgot, with this bad brass gear...could cause the variance of speed being that the projection drive sprocket is attached to that upper soundhead shaft ... which is attached to that brass gear... -monte  |  IP: Logged Eric Robinson Jedi Master Film Handler Posts: 538 From: Santa Rosa, CA Registered: Jan 2005 posted 04-04-2006 12:02 AM                     Does the sound head drive the projector head with a gear? If so, I have not seen this design before. I have had trouble in the past with a Simplex projector and a 5 Star sound head when I put a belt on with the wrong pitched teeth. The motor drove the 5 Star sound head just fine, but the belt from the sound head to the projector was riding to high on the belt drive pulley thus causing it to run at a slightly different speed. This probably doesn't help though if your situation only involves gears and one drive belt.  |  IP: Logged Will Kutler Phenomenal Film Handler Posts: 1506 From: Tucson, AZ, USA Registered: Feb 2001 posted 04-04-2006 02:23 AM                     Brett: By the looks of the pic you posted of the fibre gear, that gear looks trashed! Cheers K  |  IP: Logged Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-04-2006 06:39 AM                        Eric: Yes, the picturehead is driven directly by gears. Will: This gear is nearly brand new! It has like ZERO operational hours on it...how could it be trashed?! B.  |  IP: Logged Stephen Furley Film God Posts: 3059 From: Coulsdon, Croydon, England Registered: May 2002 posted 04-04-2006 07:53 AM                     quote: By the looks of the pic you posted of the fibre gear, that gear looks trashed! I think it may just look that way due to the angle that the teeth are photographed at in the first picture. It does look new in the second picture.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-04-2006 08:08 AM                     Be sure that your projector has the correct main drive ger set.. you cannnot use a sync gear drive set. GR-8 is the correct fibre gear in your case. Also be sure that the two screws holding the fibre gear to the main drive shaft are tight. That gear is behind that lower cover that comes off. If you post a picture of your fibre gear main drive we should be able to tell if you have the correct one. IMHO you probably have a sync gear set as that would definately cause the projector head to run slower than thhe ssound reproducer. The correct projector main drive shaft speed is 720 rpm but the sync drive gear is smaller in diameter than the GR-8 standard drive gear. Mark  |  IP: Logged Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-04-2006 09:33 AM                        Well folks, it is clear that there are two schools of thought on this problem. Konrad Schiecke (refurbusher of my Century picturehead): "There are 2 different gear boxes for the sh1000 soundhead. the original one and one for what they call sync operation,1800rpm. You should have a 1725rpm motor on your soundhead. You could have a mismatch gear box to motor." Sooo, if I am reading this right, Konrad thinks the problem is in the soundhead, and that the Simplex gearbox could be mismatched. On the other hand, Fred Blank at Tri-State (refurbusher of my soundhead) has said: "We are at the point that it almost must be the drive shaft gear set." So it appears that Fred feels the problem lies in the picturehead with regard to the lower horizontal gear set. In short, I now have two different schools of thought. Anyone else care to weigh in on this? Thanks, Brett  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-04-2006 09:54 AM                     It is possible that the century projector has the GR8 gear installed for the direct drive version If it was the gear box on the soundhead then both the projector and soundhead would both be running at the wrong speed not just one of the pair  |  IP: Logged Brett G. Sherris Film Handler Posts: 36 From: Northport, NY 11768 Registered: Jan 2006 posted 04-04-2006 10:08 AM                        Gordon, good point. One additional tidbit of information that might help the sleuthing here... When the soundhead/picturehead are coupled together, it is very hard to turn the shutter shaft knob (although it is very easy to turn the gearing from the motor side of the soundhead). Since I have turned this knob on numerous occasions when threading Century projectors at my locale reperatory house – and there never seems to be any difficulty turning this knob - does it not suggest some disproportionate gearing somewhere? B.  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.