8mm Forum: Help needed with 1680

This is topic Help needed with 1680 in forum 16mm Forum at 8mm Forum.

To visit this topic, use this URL:
https://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=5;t=001557

Posted by Terry Sills (Member # 3309) on January 28, 2017, 08:19 AM:

I have a strange problem here. When film is loaded (channel load) and the projector set to forward run, the bottom loop slowly increases until the film bunches up. Obviously the projector has to be stopped but when the film is reloaded and the projector run, the same thing happens every time. It is not a matter of misloading as the film runs fine for a few seconds but as you watch the film path you can see the bottom loop gradually increasing. It is as if the bottom sprocket is not spinning at the same speed as the top sprocket, but anyone who knows these machines will be aware that apart from the motor belt everything is driven by gear wheels, so how can this be? Has anyone had this problem or can suggest a solution please.

Posted by Richard C Patchett (Member # 974) on January 28, 2017, 09:58 AM:

Greetings Terry
Not to sure if your projector has one of theses in the uk
But on the #015533 1580/2580 there is a Lower Sprocket Gear
which breaks over time there's a metal insert in a plastic gear
the insert breaks away on which causes the film to bunch up just before the sound drum
Hope This helps I have theses gears in stock
RC

Posted by Terry Sills (Member # 3309) on January 28, 2017, 11:11 AM:

Hello Richard
That sounds a feasible cause. It must be similar to the worm gear problem? If that is the cause it must be a big job to put right and would involve a major strip down I guess. Thanks for your info.
Terry

Posted by Richard C Patchett (Member # 974) on January 28, 2017, 11:35 AM:

Greetings
On the models i listed
It sits behind the transformer
Much easier to replace that the worm gear
You really have to look for it
RC

Posted by Terry Sills (Member # 3309) on January 28, 2017, 12:35 PM:

Thanks Richard
Ok I will have a go at that. Where can I get a replacement? or is it repairable.
I just do not understand the logic of the designers of these Bell&Howell machines.
Surely it was cheaper to manufacture a solid nylon gear or worm than it is to make a metal core and cover it with a nylon outer. Just the manufacturing process must have been more expensive.

Posted by Richard C Patchett (Member # 974) on January 28, 2017, 12:42 PM:

Greetings
I have theses on my web site
#015533 1580/2580 there is a Lower Sprocket Gear
under B&H Little costly to ship priority mail
But i can send it 1st class at a cheaper rate
to help you on the cost
RC

Posted by Terry Sills (Member # 3309) on January 28, 2017, 12:50 PM:

That's good news Richard. How is the gear wheel fixed to the shaft?

Posted by Richard C Patchett (Member # 974) on January 28, 2017, 01:00 PM:

Greetings

By 1 allen set screw
RC

Posted by Terry Sills (Member # 3309) on January 28, 2017, 01:58 PM:

Richard
Sounds like something I will definitely have a go at. Will get back to you if I need a replacement gear wheel. Good to know that you have a stock of spares.
Many thanks for your help.
Terry

Posted by Richard C Patchett (Member # 974) on January 28, 2017, 02:06 PM:

Greetings Terry
Thank you
I have 15 of theses in stock
Many people don't know about this gear, They don't see it
It never gets greased
I replace this when i do a worm gear repair
Even when it looks good, Just to be sure.
RC

Posted by Terry Sills (Member # 3309) on February 01, 2017, 12:27 PM:

Richard
I thought I had a good array of Allen keys but I don't have one that fits the set screw on the gear wheel. Do you know what size I need?

Posted by Richard C Patchett (Member # 974) on February 01, 2017, 01:00 PM:

Greetings
Off hand i do not know
I got about 30 of these
I just grab by looks about the size if the 1st one doesn't fit ill try another They Are not marked on size
I'll have to take one of my gears to my tool supplier to get more of this size
And then i'll know what size for sure won't be until late saturday Sorry
RC

Posted by Terry Sills (Member # 3309) on February 01, 2017, 04:13 PM:

Thanks Richard
I've tried Imperial and millimetre but it seems to be an unusual size. I'll be interested to hear what you find.

Posted by Clyde Miles (Member # 4032) on February 01, 2017, 04:38 PM:

terry,it could be splind, ive done a few worms on these, just a guess

Posted by Barry Fritz (Member # 1865) on February 01, 2017, 08:14 PM:

You might need a Bristol toolset. Bell & Howell used set screws that required a Bristol. Lord only knows why.

Posted by Terry Sills (Member # 3309) on February 02, 2017, 01:32 AM:

Barry
That's interesting. I've never heard of a Bristol tool, are they peculiar to the US?

Posted by Terry Sills (Member # 3309) on February 02, 2017, 07:44 AM:

Double post. Don't know how that happened!

Posted by Barry Fritz (Member # 1865) on February 02, 2017, 09:54 AM:

Terry, I do not know if they are unique to the US. I am not even certain if they are unique to Bell & Howell products. I had never heard of them until several years ago when I was advised by members of 16mmfilmtalk about them. If you Google them, you will find more info and vendors. Urbanskifilm.com has them and I think you can find a set on Amazon also. Richard Patchett might comment.

Posted by Richard C Patchett (Member # 974) on February 02, 2017, 08:28 PM:

Greetings
Been doing projector repairs for over 25 Years
Never used them always found the right size allen wrench
If you like i can send you the right size At no cost to you With a order
Hello Barry
[Razz]

Posted by Barry Fritz (Member # 1865) on February 03, 2017, 05:23 AM:

Hi Richard! I think that maybe I only needed the Bristols for JAN projectors.

[ February 04, 2017, 10:58 AM: Message edited by: Barry Fritz ]

Posted by Terry Sills (Member # 3309) on February 03, 2017, 12:53 PM:

Richard
Having examined the lower gear I have determined that it is not the separation of the metal and plastic combination but that the gear is slipping on the shaft, so all I need is the correct size Allen key to tighten the grub screw. I have also found that the worm gear is in the first stage of cracking and I am beginning to think that it is a lost cause because of the cost of repair. I would not take on this repair myself.
I don't know what TQ you refer to but on mine the removal of the lower gear on my TQ3 involves much more than just removing the transformer, because it is behind the motor and other mechanism and because of this, it is also also something I would not take on. If however you can tell me the size of the Allen key it might be worth having a go at tightening the grub screw just to get it working until the worm fails altogether.

Posted by Barry Fritz (Member # 1865) on February 04, 2017, 06:15 PM:

I wonder if it is an SAE size or metric. Terry, did you try metric wrenches?

Posted by Terry Sills (Member # 3309) on February 05, 2017, 03:08 AM:

Barry
Yes I tried metric as well. Richard says he has the correct size so I am hoping that he will get back to me with it.

UBB.classic^TM 6.3.1.2