1973 Reverse lens - Found a way to make one! (1 Viewer)

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Many thanks to Living In The Past for the use of the loaner lens! Give it back to him with one of the first tries. I kept getting bubbles even when using a vacuum pot. To clarify the vacuum was to remove bubbles from the mix not the mold. I called the company who makes the clear resin for help and found out I need to cure the mold under pressure using a pressure pot. As it turned out our woodshop had one so was able to give it a try before leaving town. I did not use a vacuum pot on the mix. I went straight from mixing to the pressure pot to see the results. When I poured the resin in the mold there were a lot of bubbles.

The mold sat pressurized for one hour. I didn’t remove the lens from the model until the next day. (Drove back to Wyoming) here’s the results:

IMG_1843.jpeg

The lens was the clearest of all the test pours! The one mark in the upper left was a piece of debris in the mold! Considering I did a rush job I like how it turned out! The lens also feels stronger than the previous test pours.

I have access to a vacuum pot but will have to round up a pressure pot before my next attempt.
 
Great work!
 
Many thanks to Living In The Past for the use of the loaner lens! Give it back to him with one of the first tries. I kept getting bubbles even when using a vacuum pot. To clarify the vacuum was to remove bubbles from the mix not the mold. I called the company who makes the clear resin for help and found out I need to cure the mold under pressure using a pressure pot. As it turned out our woodshop had one so was able to give it a try before leaving town. I did not use a vacuum pot on the mix. I went straight from mixing to the pressure pot to see the results. When I poured the resin in the mold there were a lot of bubbles.

The mold sat pressurized for one hour. I didn’t remove the lens from the model until the next day. (Drove back to Wyoming) here’s the results:

View attachment 3615075
The lens was the clearest of all the test pours! The one mark in the upper left was a piece of debris in the mold! Considering I did a rush job I like how it turned out! The lens also feels stronger than the previous test pours.

I have access to a vacuum pot but will have to round up a pressure pot before my next attempt.

So if I'm reading this right the pressure pot worked better than the vacuum pump? But still haven't tried the combination of the two together? Assume the resin is a mix of at least two parts? Vacuum is done before pouring it into the mold? Once poured then into the pressure pot while it cures? What time frame do you have once the resin is mixed until it starts to set up? Not sure how much humidity plays into it being in a vacuum. This isn't HVAC work where after you evacuate a system you like sit under vacuum. Doesn't hold a vacuum you either have a leak in the system or moisture in the system boiling off.

PS that last lens looks great.
 
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So if I'm reading this right the pressure pot worked better than the vacuum pump? But still haven't tried the combination of the two together? Assume the resin is a mix of at least two parts? Vacuum is done before pouring it into the mold? Once poured then into the pressure pot while it cures? What time frame do you have once the resin is mixed until it starts to set up? Not sure how much humidity plays into it being in a vacuum. This isn't HVAC work where after you evacuate a system you like sit under vacuum. Doesn't hold a vacuum you either have a leak in the system or moisture in the system boiling off.

PS that last lens looks great.
It is a two part resin mixture based on weight not volume. From the time the two parts are poured together, not mixed, you have seven minutes to mix, evac bubbles, pour into mold, and pressurize the pot! According to the manufacture I can shorten the vacuum pot time to insure the mold is pressurized before the seven minutes is up. Not a lot of room for error!
The pressure pot I used held the pressure without loss, or minimal where I didn’t see a change, the entire hour..

The temps here in Wyoming have been too low to mix and pour so I haven’t been in a big hurry to buy a pressure pot. So for everyone following this thread, it will be awhile before my next attempt. But when I do try again, I will start a new thread and show off the progress and maybe even have some to sell and open the door for other type of lens pours too. Stay tuned……

Mike
 
Maybe a o-ring of the correct diameter and thickness could be heat formed. 7 minutes isn't a lot of working time. Maybe you pull a vacuum on each component to de-gas them somewhat prior to mixing. Maybe a magnetic stirrer would mix them better without intraining as much air - maybe while in the vacuum chamber.
 
Maybe a o-ring of the correct diameter and thickness could be heat formed. 7 minutes isn't a lot of working time. Maybe you pull a vacuum on each component to de-gas them somewhat prior to mixing. Maybe a magnetic stirrer would mix them better without intraining as much air - maybe while in the vacuum chamber.
I tried de-gassing each part and really didn’t see any air bubbles. but after mixing there are a lot of bubbles during degassing. I’ll have to check into a magnetic stirrer! Thanks for the tips.
 
I had another thought about mixing. You could buy those double barrel syringes with the lock on mixing nozzles made for 2 part epoxies. That should cut down on air bubbles, not sure it would mix the stuff well enough (the ones with a longer nozzle should mix better). I think some were listed as 50 ml per barrel.
 
Same. My original needs to be kept safe.
 

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