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Hi Michael,
I did see that one but I was not sure if it was what Kevin was referring too. Thanks, Dave.
Nice little unit that. A bit weeny though.
I modified a pressure cooker that someone threw out. That's about a foot in diameter and almost as much deep. Big enough for just about anything I want to cast.
Sorry for disappearing again- getting the last of my holidays in. (Gotta break 'em up or I can't afford to take 'em.)
Dave- I'll see if there's a part number on the pot, but the unit that Michael posted seems to be the right one. (Although mine's black, not silver.) The only complaint I'll register against the one I've got is those silly "wingnuts" for cranking down the lid- I can't get them tight enough by hand to get the pot to seal. I did come to a work around though- I turned off a special "socket" of sorts that keys into the wings and takes a 3/8" rachet drive. Now I can crank it down quickly enough that I can even pressure cast fast-cure Alumilite in it. (Adam - take note!) I'll grab a photo of this and post. (Along with the long overdue, still needs to be scanned in underwater photos from my last holiday! <embarassed>)
Okay, since a picture is worth a thousand words I'll save myself a bunch of talking and just show these- This is the Harbor Freight pressure pot I've been using to cast my RTV molds and polyurethane parts in.
As mentioned in my last post I was having a devil of a time getting the lid cranked down tight enough so that it wouldn't leak when I brought the pressure up to 70psi. My fix was a special "socket" I turned off that would let me drive down the wings using a 3/8" drive rachet. The upper end is just a cut down 3" socket extension, the lower part is the custom made "socket", and the two pieces are held together with a 1/8" roll pin.
Nice socket Kevin. I need one of those. I use the same pot, but if I crank really hard I can get mine to seal almost all the way. Far enough that mu compressor tank doesn't run down enough to lower the pressure before the part is cured.
I only go to 50 psi and that seems to be plenty. Why so much pressure?
I've been using 70psi for no better reason than "that's what the pressure pot is rated for." Naturally, the higher you go in pressure, the smaller any remaining voids will be.
If you like I can post post dimensions for my socket. Although it was a bit of work to make (as any worthwhile tool is) it's definitley been worth the effort.
I was looking over the pressure-pot story and I do not
understand. Hope someone can explain.
by putting the curing mold in the pressure pot, bubbles
seem to vanish from it.
You obviously talk about pressures larger than ambient.
that would mean the bubbles are still there, just a whole lot
smaller
I always thought you had to go vacuum to pull the bubbles
out of the liquid
(before you pour the stuff at ambient pressure) ?
Yeah but if you up the pressure you squish the bubbles out of the mould. Kind of works similar to the way injection moulding plastic displaces the air from the tool.
My modified pressure cooker has a bayonet latching system, which makes it ultra quick to use.
I have found pressure to be superior to vacuum, and much less messy, in obtaining bubble free castings. We use 5 gallon & 25 gallon pots. Only two atmospheres is needed for a good part.
Photos have been updated for the ones I got. Please look through and check if you can see the images. There will be miscellaneous blue question marks were there are emoji icons used and I chose not to find one for those, some you will see a blue question mark with a photo (I was getting my courage to replace the link completely like I did later on), and some I do not have photos for (yet).
This is an extremely fine build and I learned things just working through the images. Take some time and get inspired here.......Well done Kevin!
One goal I think SubCommittee should do is preserve information. How many times have you hit a site and all the photos do not exist? Nothing worse than seeing "This photo explains how the dohinky works" and the link to the photo is broken.
If you are the original poster and one of your builds is missing photos, please get in contact with me. I would love to restore as much information as I can.
Peace,
Tom
If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.
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