Some modification of packard shutter

[jack_hui]

Recently got a 5 inches time-only packard shutter (#5?) from eddie, by proper practice I can get around 1/4 sec to 1/8 sec ....

Why I can't get a faster shutter speed ?? By luck, I put my finger on the top of the copper piston and found that the speed increase!! well ... let's do the modification ..

This is the original packard shutter
http://www.pbase.com/jack_hui/image/123959891.jpg

These are the parts;

Spring
http://www.pbase.com/jack_hui/image/123959888.jpg

Aluminum part (not sure how to name it!)
http://www.pbase.com/jack_hui/image/123959885.jpg

http://www.pbase.com/jack_hui/image/123959886.jpg

[jack_hui]

Aluminum part with screw
http://www.pbase.com/jack_hui/image/123959890.jpg


Put all things together (you know how it works, right?)
http://www.pbase.com/jack_hui/image/123959892.jpg


Without the spring, I can get 1/4sec or 1/8sec by my careful hand-action. By inserting the spring, I can get around 1/15sec (not verified yet) ......

I am still looking for another spring, e.g. different size, length ... and see if it ends up with different speed by lowering the screw ....

[Donald Miller]

Interesting. You are on to something here.

[salihonba]

Go try some springs for BB gun, that is really strong and reacting very fast!

[Walter Calahan]

"Spring Cowling" perhaps is a good name for the aluminum part?

Cool idea. Perhaps color code your springs for various shutter speeds?

[jack_hui]

Sailhonba; tried some strong spring today, doesn't work. The copper piston isn't strong enough to push the spring all the way.

Walter; color code is a good idea ..... thanks

[Paul Bujak]

And where might one obtain one or more examples of said "Spring Cowling'?

[Tin Can]

Old thread but same old problem.

The 5" Packard I have has a similar problem. Part of the problem is this 5" like my 5" has extra bat-wings inside and is much different than my two 4.5" Packards which work perfectly.

I wonder if this solution ever worked?

[dsphotog]

Or use Jim Galli's darkslides in front of the lens method.

[Tin Can]

Or use Jim Galli's darkslides in front of the lens method.

No way can I do that. I have watched his wizardry. I need a gadget.

[domaz]

I bet if you replaced the return spring in your Packard shutter and used the instaneous pin you could get a faster shutter speed without all this bother. The return springs are often weak.

[Tin Can]

I usually use the pin, but how do I spec that spring?

I suppose i can buy a few dozen from McMaster till I find the right one.

The 5" is the first to give me trouble like this. The spring seems fully coiled and not stretched. The whole thing is VGC low mileage.

I blame the design which is significantly different than any other Packard I have.

I recounted, I have 8. I like them, but I have one lens that could use this extra 1/2".

I'll get it.

Thanks for the advice.

[Jim C.]

fwiw, I've speced springs by measuring the wire gauge, diameter of the coils and the length.

[Tin Can]

fwiw, I've speced springs by measuring the wire gauge, diameter of the coils and the length.

I'll keep that in mind. Maybe I will load test some on my soon to be spring Dyno.

[Jim C.]

I'll keep that in mind. Maybe I will load test some on my soon to be spring Dyno.

" spring Dyno " ?

[Liquid Artist]

" spring Dyno " ?
Didn't we all test spring strength in high school by stretching them out with weights?
Which is in a sense a Spring Dyno.

[Tin Can]

Didn't we all test spring strength in high school by stretching them out with weights?
Which is in a sense a Spring Dyno.

Exactly. I used machines like this (http://www.engineeringfasteners.com/about.html) for decades. A nerd's delight. My company pioneered this exact tech, which is now de rigor. I taught Detroit, they needed us badly.

[Jim C.]

Didn't we all test spring strength in high school by stretching them out with weights?
Which is in a sense a Spring Dyno.

Didn't know it actually had a name.

[Jac@stafford.net]

Exactly. I used machines like this (http://www.engineeringfasteners.com/about.html) for decades. A nerd's delight. My company pioneered this exact tech, which is now de rigor. I taught Detroit, they needed us badly.

Among the lot of instruments we use those in our Composites Engineering manufacturing facility (http://www.winona.edu/engineering/facilities.asp). Randy, you would be in heaven exploring the products being made.

[evan clarke]

Wow, I get a consistent 1/30 with my pump

[Tin Can]

Among the lot of instruments we use those in our Composites Engineering manufacturing facility (http://www.winona.edu/engineering/facilities.asp). Randy, you would be in heaven exploring the products being made.

I worked in Product development most of my life and automotive during all of it. First at Crane Packing in 1972 and decades for Fel Pro. Often used MTS and Instron machines. Once a million lb MTS Load Frame at Northwestern Univ. It was huge. Electro-Motive (https://history.gmheritagecenter.com/wiki/index.php/The_Electro-Motive_Story) parts. We had 2 cylinders of a locomotive, operational for live testing.

While at Fel Pro we went from Studebaker engine Dynos to 6 modern cells that became obsolete long before we stopped using them. During asbestos replacement testing I was all over the place, Detroit, San Antonio, Ann Arbor. Jack Roush racing sent us lot's of engines. We often got 6 packs of Chryslers on one big skid. Then we raced the Hell out of them using tankers of special Dyno test gas that cost way more.

I really miss the roar of 6 engines all at WOT (wide open throttle) full load for 100's of hours. Racing sitting still. Eh WOT? I can't hear you... :) Dyno joke.

I studied the history of Dyno testing engines which is as fascinating as old photography and occurred during the same time period. Horsepower!

[Harold_4074]

If you really snap a Packard shutter (modern design, anyway) hard enough you can break the blades, usually at the lower pivot points. This from Reno at Packard Shutter Company, who graciously repaired a nearly new shutter of mine which for some reason failed at a completely different point.

The older blades are something like phenolic-paper, which can be glued, but the current ones are apparently polypropylene or nylon, neither of which are really amenable to cementing. I think that if I really wanted to exceed the factory speed, I would look to some sort of shock absorber at each end of the stroke; the momentum of those rotating blades is considerable, and the original design makes no provision for absorbing it other than be deflection of the working parts.

[Tin Can]

If you really snap a Packard shutter (modern design, anyway) hard enough you can break the blades, usually at the lower pivot points. This from Reno at Packard Shutter Company, who graciously repaired a nearly new shutter of mine which for some reason failed at a completely different point.

The older blades are something like phenolic-paper, which can be glued, but the current ones are apparently polypropylene or nylon, neither of which are really amenable to cementing. I think that if I really wanted to exceed the factory speed, I would look to some sort of shock absorber at each end of the stroke; the momentum of those rotating blades is considerable, and the original design makes no provision for absorbing it other than be deflection of the working parts.

I think you just made the old ones more desirable.

Most that I have opened have little triangular bumpers in the bottom outside corners, which are all dried up. My so slow 5" had bits of hose in those location on metal pins. I tried new hose there and I made matters worse.

1/25 th is the factory spec and one I can now achieve after my hands started squeezing better, on 3.5 inch and smaller. The 3.5" ones work real good. I have one with metal blades.

Wish I still had access to a laser cutter...

[Harold_4074]

I don't know much of the history, but I think that we use "Packard" as a sort of generic name for shutters made by different manufacturers to varying internal designs. I have one which has to be mounted with the air cylinder horizontal, since the weight of the piston (machined from solid brass) is enough to close the shutter in the absence of air pressure. I described it to Reno, who said it was definitely not a Packard Shutter Company product. (Mounted conventionally, it is a bear to focus through....)

My guess would be that the ratio of piston travel to center-of-mass blade travel would make effective damping problematic, given the confines of the case. What you would need would be some kind of frictional damping--not elastic, like rubber---to slow down the blades gradually at the ends of the stroke. Of course, this would require more piston force for a given speed, raising the stress on the drive notch and lower pivots, just as Reno described.

Also: I usually use the pin, but how do I spec that spring?

You could consider contacting Packard Shutter, sending a picture of the shutter interior and asking if the "correct" spring can be had as a repair part. Assuming, of course, that your shutter came originally from the Packard Shutter works :)