Thread: Quick small vac pot

130mm is not very high. You need to cover the piece you are stabilising by about 25mm at least and then allow for extra room when it bubbles up so you don't get resin in your vac lines.

Originally Posted by Flintlock

130mm is not very high. You need to cover the piece you are stabilising by about 25mm at least and then allow for extra room when it bubbles up so you don't get resin in your vac lines.

I agree but this pot is not for stabilising pieces - it's for de-bubbling small amounts (<10mL) of just mixed resin prior to pouring into gaps and cracks.

Originally Posted by BobL

I agree but this pot is not for stabilising pieces - it's for de-bubbling small amounts (<10mL) of just mixed resin prior to pouring into gaps and cracks.

That's great then.
I'm in the process of building one for stabilisation. Just looking for some polycarbonate for the top and bottom.

Originally Posted by Flintlock

That's great then.
I'm in the process of building one for stabilisation. Just looking for some polycarbonate for the top and bottom.

I see its available on ebay, - an A4 sheet of 3mm costs $20 with free shipping and 6mm is only $25
CLEAR & GREY POLYCARBONATE UV RESISTANT SHEETS - PANELS - FREE TRACKED SHIPPING | eBay

I worry about some stuff advertised as PC might not be.
The link above shows as Makrolon which is good stuff.

I too am looking at building a stabilisation setup. I have the "pot", a Supercheap paint pot, now I need a lid. If I use acrylic sheet it looks like I need something 15 to 19mm thick which is not available locally. Watching things on youtube turned up a bloke somewhere in the northern hemisphere that poured his lid out of clear resin about 25mm thick. Having no experience with the stuff, is that a feasible solution to the problem? If I could use clear resin then I could just cast the vacuum fittings in place, no threading needed. And apparently the resin isn't affected by the vapours given off by Cactus Juice, unlike some other materials (acrylic sheet has been mentioned, as has Polycarbonate).

Withs the diameter of the top of your pot?

When the sun comes up I will wander out to the shed and find the pot and measure it. This is the video I was talking about. DIY | Casting Vacuum Chamber - YouTube Not about timber stabilisation but it gave me an idea.

The dimension of the ridge where the lid seals to the pot is around 245mm so to allow for a gasket of some sort I would say the lid would have to be somewhere in the vicinity of 265 or 275mm. One of the problems I can envisage is the weakening effect of drilling holes in the material. Most commercial chambers have the outlet hole in the centre of the lid and it seems that these lids often develop cracks somewhere near that hole, or at least the ones on youtube seem to be like that. Perhaps it would be better to go through the side of the chamber rather than through the lid? One of the eBay suppliers seems to do this but is this for cracking prevention or just because it's quicker to drill a hole on the side of the chamber than to drill and tap the acrylic sheet, I don't know? There would need to be some sort of curved spacer on either side of the through-hole fitting but that wouldn't be too hard to fabricate out of either wood or plastic.

275mm or 27.5cm and 2.5 cm thick translates to
(27.5/2)^2 x Pi x 2.5 = ~1500 cubic cm, or 1.5L of resin
I don't how cheaply you can get resin but that wold seem like a waste of resin to me.

RE: hole in the top.
The main reason I drilled my holes in the side was for visibility but to drill and tap into curved sides the walls need to be thick enough to retain at least a couple of thread turns.
Most fittings are BSP threaded so to tap these threads you will need BSP taps. To get more threads in the hole smalled BSPfittings should be used eg 1/8 or 1/4".
A curved space or gasket should also work and then you might get away without any threading.

Off topic, but moving that firkin tank of a vacuum pump I describe in my first post I reckon I have done myself a back injury. As I said it weighs 45kg and has a single lifting handle. It's weird that apart from 'Wow this is bloody heavy!" I did not feel much at the time - it was only a day later I woke up with a bit of a sore back, during the next few days it got worse, especially sitting or laying down. Even today (4days later) its still painful so have been gobling Advils to help. I going to build a dolly for it so that it makes it easier to put it back under the house where it usually lives.

If I decide to build a bigger pot my plan was to use a piece of 6mm thick steel (which I can get as an off-cut from a steel merchant) as a top, and cut a hole in it for a viewing window made out of polycarbonate.
It would then be possible to drill the steel section of the top for the fittings/connections and leave the PC section unobstructed.

I would need to check the price of water-clear resin at places like the big green shed, I realise it won't be cheap but neither is polycarbonate sheet, especially if you need to get it transported from Sydney or Brisbane. If I could get hold of thick enough polycarbonate sheet I think I would still go through the side of the pot and use a shaped backing piece on either side of a threaded feed-through and add some sealant just to be on the safe side. The porthole viewing window seems like a good idea but getting it to fit on the domed lid of a Supercheap pressure pot might be a bit beyond me. An el cheapo video camera might just work though.
Good luck with the back pain. The combination of lifting, bending and turning all at the same time is a share recipe for disaster.

Originally Posted by Old Hilly

I would need to check the price of water-clear resin at places like the big green shed, I realise it won't be cheap . . .

If you're referring to clear casting resin, bunnings sells it for ~$40 a liter so you would need ~$60 worth.

but neither is polycarbonate sheet, especially if you need to get it transported from Sydney or Brisbane. If I could get hold of thick enough polycarbonate sheet I think I would still go through the side of the pot and use a shaped backing piece on either side of a threaded feed-through and add some sealant just to be on the safe side.

Are you talking pressure or vacuum? Everything I've referring to is for vacuum.

If you're referring to pressure, and want to have the entire top transparent I'd be using 10mm thick PC sheet, but that works out as expensive as resin.

The porthole viewing window seems like a good idea but getting it to fit on the domed lid of a Supercheap pressure pot might be a bit beyond me. An el cheapo video camera might just work though.

If the steel is thick enough - I'd use 6mm for pressure - the lid won't need to be domed and the PC window could be glued in from the inside. Also 6mm PC would be fine as a small porthole window.

Good luck with the back pain.. The combination of lifting, bending and turning all at the same time is a share recipe for disaster.

Yep that's what I did.

Yes Bob, I am talking about vacuum here. 10mm PC sheet isn't cheap and neither is the freight. Then there is the problem, if in fact it is a problem and not just something repeated ad nauseam on various fora, of polycarbonate being susceptible to chemical attack from the vapours of "Cactus Juice" stabilising resin.
As for your back injury, I hope yours recovers faster than mine, at least I could walk through the big green shed today, first time in 3 weeks after I did just what you did. Getting older does not mean getting smarter, so it seems.

Originally Posted by Old Hilly

Yes Bob, I am talking about vacuum here. 10mm PC sheet isn't cheap and neither is the freight. Then there is the problem, if in fact it is a problem and not just something repeated ad nauseam on various fora, of polycarbonate being susceptible to chemical attack from the vapours of "Cactus Juice" stabilising resin.

If you like I can send you a piece of 1mm thick PC that will fit in a standard envelope and you can test it in your next batch.

That's sort of why I suggested a smaller PC window in a steel lid - then 6mm could be used and it replaced every so often,

As for your back injury, I hope yours recovers faster than mine, at least I could walk through the big green shed today, first time in 3 weeks after I did just what you did. Getting older does not mean getting smarter, so it seems.

Mine's not that bad, I've been driving around all morning and that hasn't done it much good but I felt worse getting up from a 30 minute lay down