8mm Forum: Elmo Take up /Rewind tensions

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Topic: Elmo Take up /Rewind tensions

Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted September 20, 2012 03:49 PM

Hi all, looking for some expert advice on the above. I have two machines, both are in excellent well preserved condition by their previous owners. My question is that on my original ST1200 I easily able to compensate and adjust the take up spool and rewind arm tensions by virtue of adjustments to the spring tensioners fitted as a clutch to each of the gears at the end of the drive chain just prior to their respective arms. This worked with great success and now comfortably rewinds even 1600ft supaspools loaded full with film.The problem I have is I cannot replicate this success with my ST1200HD despite the fact all belts and tensions seem very goood with what appears nearly new drive belts. The HD even has the shutter wheel belt attached which I have never seen still intact on any other ST I,ve had! I've adjusted the spring tensions as far as is possible in order to give the gears the best possible chance of driving the load and the motor is very quiet no vibration and drives the film path very well even with 1200ft spools. It just slows right down and comes to gradual halt whenever rewinding over 1000ft of film. Any help on resolving these issues would be gratefully received!

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"C'mon Baggy..Get with the beat"

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Hugh Thompson Scott
Film God

Posts: 3063
From: Gt. Clifton,Cumbria,England
Registered: Jan 2012

posted September 20, 2012 05:33 PM

Hi Andrew,could it be that the take up arm is not as free, therefore
providing that little bit of resistance to rewind.If the spool was on
a "free" arm I reckon it would rewind quite happily.Try putting
the spool on a piece of dowel or a pencil while rewinding just to
show what I mean.

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted September 21, 2012 11:50 PM

Thanks for that Hugh, the one area I've yet to inspect is the gearing within the arm itself of which there are around five if memory serves me correctly. I shall, on my next oppertunity,remove the small coverplate on the front of the arm assembly and check the status and condition of the nylon gears within. They may also need lubricating with lithium or alvania grease as I found most of the internal gears were somewhat dry on arrival of my new pride and joy! Thanks again Hugh, write back soon once I've tried.

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"C'mon Baggy..Get with the beat"

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted September 23, 2012 03:46 PM

Been through the drive chain on the rewind and take up arms now Hugh. It seems there is absolutely nothing wrong in any of these areas although I did add a little copper grease as all of the gears were rather dry.Having observed several times the rewind action of the machine with the rear cover removed, it appears the fault lies within the two gears that are assembled together on the clutch driven mechanism described earlier. One of the gears (the smaller spur gear which is ultimately driven from the worm gear on the main drive) appears to have no physical connection whatsoever with the output gear on this rewind clutch driven shaft whereas I am sure that on my other ST1200 they are joined by a key and keyway or some kind of drive peg. I will observe on the other machine once I have sufficient time away from work and make the drives the same. I am sure that once this work has been carried out this machine will rewind just as powerfully as my other.I will report back my findings on here once I get around to carrying out the work.Thanks again Hugh as tose gears really were running bone dry!

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"C'mon Baggy..Get with the beat"

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Hugh Thompson Scott
Film God

Posts: 3063
From: Gt. Clifton,Cumbria,England
Registered: Jan 2012

posted September 24, 2012 07:24 AM

You're more than welcome Andrew,although you do seem very
adept at finding your way around the innards of the Elmo.I have
one like yourself that just before the end of a rewind it will slow
down, but I've checked the cogs and can find nothing,but it is
an old machine.

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted September 29, 2012 06:46 PM

I think there may well be excess lubrication between the two spur gears that are mounted on the common shaft that forms the clutch mechanism for rewinding Hugh. I am going to try to clear some of the grease from the assy once dismantled and if necessary fit a rubber friction lining beteen the two gears as the drive relies solely on friction being asserted from the spring tension fitted to the collet at the front of this shafts assembly. This hopefully will give the drive far more torque than is currently available and hopefully should completely rewind a 1600ft movie without grindind to a halt at around the 1000ft mark as is currently the case. If this works with success without overloading the induction motors capabilities then I will post some photos on here of the mod in case others are or have suffered from a similar experience. Keep you posted once I have had chance to work the issue, hopefully Monday!

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"C'mon Baggy..Get with the beat"

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted October 01, 2012 01:39 PM

This did turn out to be be very much a case of excess grease making its way inbetween the two spur gears mentioned earlier at the rewind clutch section of the machine. Having split the assembly and cleaned all the inner faces of the gears I found also sandwiched between the two gear faces a fibre friction lining that was also contaminated with grease. This is all that drives the inner gear from the outer spring tension so obviously it relies on being bone dry and free of lubricants. The projector still only rewinds a 1200ft spool and not a 1600ft spool like my other before the motor actually stalls so in future I will use my other machine to rewind features over 1200ft as the motor is visably more powerful than that of the HD. Although I am dissapointed that my best machine has the weaker and perhaps greater used motor fitted to it I have to bear in mind that these machines were only ever designed to handle 1200ft of film not 1600ft on heavy metal supaspools so to that end I have at least restored the machine to its design capabilites [Smile]

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"C'mon Baggy..Get with the beat"

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted October 02, 2012 08:41 AM

Also noticed that the gear ratios are very much different on the standard ST1200 to that of my ST1200HD and the old ST makes the job of rewinding a lot easier as the gear ratio favours rapid rewind on this machine. Anyone know what the idea of the upgrade on the HD was supposed to be for? As far as I can see there are only negatives from the modification???

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"C'mon Baggy..Get with the beat"

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Vincent Zabbia
Master Film Handler

Posts: 372
From: Montrose, NY
Registered: Feb 2011

posted October 02, 2012 02:08 PM

The clutch is engaging (two plastic pieces) which makes the rewind tough. Rewind a film with the back removed. Watch and notice this. An adjustment has to be made. Might also need an adjustment to the metal pitch fork looking thing which is right next to the rewind mechanism...

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Vincent Zabbia

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Andrew Woodcock
Film God

Posts: 7477
From: Manchester Uk
Registered: Aug 2012

posted October 03, 2012 11:06 AM

Thanks for that Vincent will check out the other drive chain further with the "pitch Fork" attachment on it

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"C'mon Baggy..Get with the beat"

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