8mm Forum: Two blades ST1200

This is topic Two blades ST1200 in forum 8mm Forum at 8mm Forum.

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Posted by Dominique De Bast (Member # 3798) on June 17, 2018, 11:27 AM:

I saw on EBay an add for an Elmo two blades shutter that is supposed to fit all the models. I asked the seller (who hasn't replied, yet) if he's sure that it would suit a ST 1200 model as I know they have a specific design. FFR, in Germany upgrade the ST 180, the GS 800/1200 but not the ST 1200 with their own (2 or 2/3 blades) shutters, so there must be a reason. I've just open my projector and noticed it looks difficult to remove the existing shutter but what's more, it's a 4 blades one ! Am I right if I say it takes more light than a 3 blades shutter ? And has anyone successfully remove one of those pieces from a ST 1200 to replace it by a 2 blades one ?

Posted by Maurizio Di Cintio (Member # 144) on June 17, 2018, 12:19 PM:

Yes, you are right: you are getting about 25% less light than you could: three blades are OK for screening films at 18fps and certainly more than necessary for 24. Now the shutter assembly of this model is way more complicated than other Elmo's, but replacing the shutter with a 2-bladed one is not impossible at all: I know a person who does it in Italy and certainly there must be in other places...

Posted by Dominique De Bast (Member # 3798) on June 17, 2018, 12:33 PM:

Thanks, Maurizio. When you say that someone in Italy does it, do you mean that he did for his own projector or that he offers this service for everyone ? My projector is not working at 18 fps (but since I have other machines, it's not a problem) so a 2 blades shutters would be perfect in my case.

Posted by Jean-Pierre Labus (Member # 6090) on June 18, 2018, 02:01 AM:

4 different shutters for HEURTIER Stereovox Super 8mm sound projector.

1/ Original shutter 3 blades for 18 or 24 fps

2/ Modified shutter 2 blades fps controled by laser for video transfer

3/ Modified shutter 1 blade fps controled by laser for video transfer

4/ 3D printer created shutter 1 blade fps controled by laser for video transfer

http://8mmforum.film-tech.com/cgi-bin/showpic.cgi?dir=uploads0503&file=4obturateursrnnduit.jpg

It is possible to modify ST-GS 1200 in the same way...

Posted by Steve Klare (Member # 12) on June 18, 2018, 08:45 AM:

I'd love to do two blades on my own ST-1200, but that could be an easy thing to do badly. On most machines the shutter just does an optical job: interrupting the beam. It can be pretty flimsy and do just fine. The ST-1200 shutter is structural: it holds up the ring that accepts torque from the rollers. If you went from three blades to two it would leave a large angle of open space under the wheel, and it might want to stop being round if it wasn't strong enough.

Impossible?

Not at all!

It's just something that would need to be done right: good design,strong materials, skilled work.

-I'd buy that!

I wouldn't want to ship a machine to Italy and back, but if I could buy the part I'd probably wait until the machine died and make it part of the fix.

Posted by Tom Photiou (Member # 130) on June 18, 2018, 02:45 PM:

Although ive never really been interested in changing the shutter from 3 to 2 blade i have changed a few of these now. The last one was a bit of a nightmare as the ST1200HD shutter is a slightly different size to the ST1200, as is the motor pulleys.

Posted by Steve Klare (Member # 12) on June 18, 2018, 03:04 PM:

Tom,

How is the shutter mounted to the main shaft?

Thanks!

Posted by Tom Photiou (Member # 130) on June 18, 2018, 03:22 PM:

There are two tiny grub screws, once these are loosened it should pull / slide off, it is a very tight fit, i have had one or two where i was very worried i was going to do some damage with the force i needed to get it off.

Posted by Steve Klare (Member # 12) on June 18, 2018, 03:27 PM:

Judging from the location these are probably camouflaged in grease, correct?

Is the shutter keyed on the shaft?

Posted by Tom Photiou (Member # 130) on June 18, 2018, 04:02 PM:

to get the shutter off you need to remove the machine frame assembly, its not keyed, once fitted you have to set up the "timing", i think i put up a thread on this some time ago Steve, i will try and find it and put a link on. [Wink]

This was my last experience, not quite what your looking for but its a start. If you look at the image of the pulley you will see the grub screws, these are the same type holding the shutter in place. Early 1200s only had one, later ones and the HDs have two.

http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011982# 000000

Better still, here you go Steve, this may help.

http://8mmforum.film-tech.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011672#000000

Posted by Dominique De Bast (Member # 3798) on June 19, 2018, 05:34 AM:

Thanks for all those feedback. The EBay seller has not replied, yet. I'm still intersted to know if it's possible to have a modification made in Italy (or elswhere else).

Posted by Maurizio Di Cintio (Member # 144) on June 19, 2018, 07:45 AM:

The person I know is based in Northern Italy and offers that mod for others too. I'll retrieve his contact details and PM them to you later.

Ah, and the mod does not impact on structural issues: there should be non concern as for such regard. Cheers,

Posted by Dominique De Bast (Member # 3798) on June 19, 2018, 10:06 AM:

Thanks a lot, Maurizio !

Posted by Maurizio Di Cintio (Member # 144) on June 19, 2018, 01:27 PM:

You're most welcome!

Posted by Dominique De Bast (Member # 3798) on June 19, 2018, 01:37 PM:

I sent an e-mail to the Italian gentleman and he answered (in English) after a very short time. To be sure (it seems that a 4 blades shutter is not the norm on this model, so I may have not seen properly but I'm not at the moment in the same place than the projector), I will send more pictures tomorrow but it seems that it's possible to replace the existing shutter by a 2 blades one. The only dark point is that I will have to send my projector and trust the post but I have no other choice.

Posted by Thomas Knappstein (Member # 6134) on June 23, 2018, 12:33 AM:

In the Past i changed to a self made two blade shutter Wheel in an original standard ST 1200. The Light output was not much higher than the three blade shutter. Why not?
The Problem is the Head proof Glas in the black Lamp house. But if you throw it away, the Filmpath will get to hot.
So the right Way to do this is mount a DC Motor into the Machine for the Calw mechanic. Than you can change wo Lines of the big original AC Motor and the Fan blows otherwise. Now you can take the heat proof Glas out and it will not be to hot. The Two blades could have a 40 degree dark phase. Now the Lightoutput is even brighter than the standard machine. And use the Elmo Zoom 1:1,0.
A little computer Fan on the Front of the Projektor for more cooling is a good Option.

I did this a few Years ago and it was much much work.

Posted by Graham Ritchie (Member # 559) on June 23, 2018, 06:55 PM:

That's fantastic Thomas [Cool]

what voltage is the DC motor and is that a variable speed control at the front? [Smile]

Posted by Thomas Knappstein (Member # 6134) on June 24, 2018, 01:18 AM:

Hi Graham!

I rebuild the complete ESS electronic from the GS 1200 in an external Housing to drive this Motor. So I can use this ST1200 like a GS with ESS Sync The Sound is comming from a special made DVD.

Posted by Graham Ritchie (Member # 559) on June 24, 2018, 11:52 PM:

That's brilliant Thomas [Cool]

Posted by Tom Photiou (Member # 130) on June 25, 2018, 03:47 PM:

i take my hat of to anyone who can do this sort of work. [Wink]

Posted by Dominique De Bast (Member # 3798) on June 26, 2018, 07:53 AM:

Thanks for having talked about the filter, Thomas. I asked the Italian specialist about this and he told me that his home manufactured two blades shutters are designed to have also a fan function so he removes the original filter and replaces it by a normal piece of glass. Since I intend anyway to use the projector only at 24 fps, it should be ok. I'm impressed by what you did.

Posted by Thomas Knappstein (Member # 6134) on June 26, 2018, 09:46 AM:

Hello Dominique!

In my ST there is no Glas in the Lamphouse.
But I have a little Computer Fan on the Front Cover.

Posted by Dominique De Bast (Member # 3798) on June 26, 2018, 11:08 AM:

Looks great !

Posted by Daniel Macarone (Member # 5102) on June 26, 2018, 09:38 PM:

Hi Thomas, How long have you been using your ST-1200 with extended arms for long play?

Posted by Thomas Knappstein (Member # 6134) on June 26, 2018, 10:26 PM:

I have used it many Times.
The Reels are on there have a running Time of two Hours.

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