Large Packard Shutter - Time Control

[illumiquest]

So I recently found a very large Packard style shutter off a copy camera, one with a 24v electric motor to open and close the mechanism. I'd like to try mating this to my 8x10 and 16x20 camera but need a way of setting shutter speeds up to 1/60th.

I've searched around a little for simple relay timers but none of them seem to adjust past 1 second.

Has anyone found something cheap that works with this or have any suggestions of what I might try?

 

[John Koehrer]

Try Edmunds scientific or American Science + Surplus for(science project) kit. They're not expensive or difficult to build. I picked one up that even has a solid state relay(single pole, double throw) on the board. Vellman is the brand.

I'd think about finding a motor that runs on a lower voltage to save weight & space on power supply.

 

[cowanw]

I have never heard that Packard shutters are capable of 1/60 sec, some ilexpo shutters can be wound up to perhaps 1/20 sec.

 

[BAC1967]

I have a pneumatic Packard shutter, the fastest it will do is about 1/15.

 

[illumiquest]

Gotcha, what’s the limitation?

 

[cowanw]

Mechanics and physics; size of shutter blades and strength of spring. Although a Sinar shutter can do faster speeds.

 

[illumiquest]

I was going to swap out the original plastic shutter blades with thinner and lighter carbon fiber. The weight is half that of the plastic and the strength should be considerably better, especially if I were to double layer where the blades connect to the frame. I'll have to experiment with how quickly that goes before things fly apart.

Try Edmunds scientific or American Science + Surplus for(science project) kit. They're not expensive or difficult to build. I picked one up that even has a solid state relay(single pole, double throw) on the board. Vellman is the brand.

I'd think about finding a motor that runs on a lower voltage to save weight & space on power supply.

I looked at that site but all of the relays I saw were only good down to 1 second, not sure if you'd seen something which operates faster?

 

[John Koehrer]

I had a mental disconnect. I saw the 1/60 and then faster than but interpreted it as longer.
Xin Loi

 

[jim10219]

Most kids these days would control it with a Arduino board. It’s software a programmable system, which some people find easier than raw circuitry. Personally, I would likely just build my own timing circuit and use that to control a relay to activate a solenoid, and forgo all of the current electronics it came with. Especially if I was building my own carbon fiber blades. That would take a bit of circuits knowledge, or some moderate research to pull off, but it shouldn’t be too complicated to be outside the realm of a DIYer with an intrepid spirit. Variable timing circuits were some of the first circuits we built in my introduction to circuits class.

 

[illumiquest]

Most kids these days would control it with a Arduino board. It’s software a programmable system, which some people find easier than raw circuitry. Personally, I would likely just build my own timing circuit and use that to control a relay to activate a solenoid, and forgo all of the current electronics it came with. Especially if I was building my own carbon fiber blades. That would take a bit of circuits knowledge, or some moderate research to pull off, but it shouldn’t be too complicated to be outside the realm of a DIYer with an intrepid spirit. Variable timing circuits were some of the first circuits we built in my introduction to circuits class.

Thanks Jim, I had a friend who does the Arduino stuff bang something together, looks like he's got something that'll work,i'll post photos of it when its together.

 

[Old-N-Feeble]

I suggest you opt for a solid state relay to eliminate the dwell time and inconsistencies of a coil type.

 

[illumiquest]

Yep, I believe he has a solid state.

 

[Ian Grant]

I bought a timer kit from a UK store last week, while it's 1 second to 15 minutes I figure the circuit can easily be tweaked for faster speeds. I have 3 (Prontor?)m electronic shutters that need controllers. Unfortunately the chain of stores "Maplins" is closing down, I'll see if I can buy more in the closing down sale. Radio Shack probably sell a similar kit.

The Packard won't use a motor it'll be a simple solenoid.

Ian

 

[Old-N-Feeble]

Illumiquest, if your controller works well, could you share the design? I need one too.

 

[illumiquest]

So here's a prototype of the controller activating the 4-1/2" shutter. The solenoid on this shutter is pretty weak so it's only good up to 1/8th of a second. The next step is testing ballsier solenoids to see if that can get the speed up, if that doesn't work (and I doubt it will) the next move would be to design a new shutter mechanism. I'm leaning towards a four bladed design similar to the Sinar Copal but using a solenoid on each blade to minimize moving parts.

 

[Old-N-Feeble]

Depending on maximum shutter speed needed, the best option might be to make lighter weight moving parts, in addition to swapping in a faster, more efficient solenoid. In fact, two small solenoids in push-pull configuration might speed up activation. I can't remember... do the blades have a return spring or weight? If so then removing that and relying solely on the solenoids might speed it up a bit... the solenoids would be always active holding the shutter closed immediately prior to dark slide removal.

 

[illumiquest]

I definitely think the moving mass needs to be reduced as much as possible, I have some thin carbon I was going to make the blades out of which would cut the weight at least in half. There's a very weak return spring on the existing rotating solenoid but the unit is definitely not strong enough to move these shutters at a high rate of speed.

 

[glbeas]

Think of designing blades that operate like curtain shutters do. Each large enough to fully cover the aperture, one opens to full, the other closes immediately afterwards. This will require no return action so can be made to operate faster with strong enough solenoids.
Then the only thing to worry about is how to damp the recoil from the movements so the camera is not jumping when you fire the shutter.

 

[illumiquest]

Yep I’ve been thinking of a two opening design, basically two separate shutters that are synced to fire sequentially so one opens and the second closes with the time between controlled by the computer.

 

[glbeas]

The real limiting factor is how fast you can move the blade out of the way in any shutter, your carbon fiber will help. Also the f-stop setting will modify the overall length of exposure, as at small apertures ithe shutter is apparently fully open a lot sooner than when at max aperture. Another factor is counterbalancing the blades. A multiblade shutter has the blades moving in opposing directions all the time so it cancels vibration for the most part. A curtain action will need an opposing counterweight in the system to do the same as the blade move independantly. This isnt much of a concern with the big slow moving shutters but as you speed up the action the energy involved has to go somewhere.
Just a few thoughts to consider. Good luck, Id love to see the final result.

 

[glbeas]

Another thing I remembered from some obsure and dusty corner, rotating disc shutters. Has a hole in one half, obviously balanced for weight and the rotation speed setting the exposure time. Two counter rotating discs could give you some pretty high speeds with minimal vibration during exposure.

 

[jim10219]

Good work on the controller! I agree that a new solenoid would probably give you more speed. The issue would be, would it destroy the blades, and can you get enough power to it to achieve those speeds?

If you're going to go with a curtain shutter design, I'd consider repurposing an old Graflex Speed Graphic, or at least checking out the design for some inspiration. Using a relatively narrow slit, they can mimic speeds as fast as 1/1000, though getting a flash to work with it will be really tough. Plus they're extremely simple designs, yet pretty accurate and reliable. And while they do vibrate a lot and cause a good bit of camera shake, the vibration and shake mainly takes place after the shutter has passed the film plane (and comes to a stop), so it usually doesn't have much (if any) effect on the image. At least that's been my experience while using one.

 

[illumiquest]

Thanks Jim, I've used the speed graphics before and seen them modified to be used as the shutter on other cameras but since much of my work requires strobe they wouldn't work for me. I guess I wanted to see how far a bladed design could be pushed. All the old packards I've found, or other large bladed shutters, use plastic which is obviously not going to take a huge amount of force to destroy. With a stronger material speeds should be able to go up, hopefully to at least 1/60th.

For power I'm using a 20v lithium battery pack off a screwdriver. I forget how many amps it is but its got plenty of juice to smack a solenoid open extremely quickly.

Gary I like the idea of counter rotating disks, that would take care of the start and stop issue with blades. I'll draw something up in cad and see how it looks.

 

[Andres Riusech]

Hi Giles, you look ready to experiments, why you dont try with a guillotine, with some previous calculation and tests you can get any speed depending of the size of the hole (square) as in the digital, i think.
Andres