Pressure pot

[Big Shed]

Yes, another pressure pot thread! I have posted this by request from another forumite (hope it is clear enough Amos:2tsup:)

Have just completed setting up my SuperCheap Auto pressure pot for resin casting and blank stabilising.
Having looked at most of the pressure pots set up for this, most in the US supplied mainly by Harbor Freight, I was somewhat daunted at first by the complexity of some of the setups.

Granted some were dual purpose pots, set up for both pressure and vacuum.

A recent thread on IAP¹ conformed more to what I considered a workable minimalist approach, eliminating most of the complexity of previously viewed set ups.

1 First order of business is to strip everything off the lid of the pressure pot, then remove to paint intake tube from underneath the lid. A ot of people have reported great difficulty with this task, I was however fortunate that fairly frim pressure on a pipe wrench got it moving and I got it removed. If you can't get it removed, or dont' want to, just cut it with a 4" grinder and a cut off wheel.

416251

2 When you look on top of the lid there are 2 threaded entrance holes, one is 3/8" BSP (the bigger of the two) and the other apparently 1/4" BSP (more on this later). I wanted to use the bigger (3/8" BSP)for the air inlet. First order of business was to step this down to 1/4" BSP so it would take a 1/4" BSP fitting. I bought all my fittings form the local Bunnings Warehouse.

416252

3 I then fitted a 1/4" BSP cut off valve and as my air system in the shed uses Ryco fittings, a Ryco male plug.

416253

4 Here we see the inlet side completed

416254

5 Most of the designs I have seen keep the supplied regulator. I don't see the need as all we are doing is bringing the pressure pot to a certain PSI, so all we really need is a pressure gauge.
The original T piece was going to be used for this with the gauge mounted on one end, the opposite end fitted to the smaller of the 2 threaded holes on the lid and a pressure relief valve fitted to the male thread coming out on the left. This didn't work as the thread opposite the pressure gauge (male 1/4" BSP is a very sloppy fit and the thread at right angles is the right fit for this hole and what's more it doesn't take a female 1/4" BSP fitting. Don't quite know what it is, but it was originally the thread that fitted that hole, so a change of plan here.

416256

6 Here we have the original right angle fitting that held the regulator fitted back to the T piece with the pressure gauge mounted directly to it. Also we have a 1/4" BSP cut off valve fitted to the other side of the T piece.
I could have used the original safety pressure valve here, but didn't see any purpose in this. When you are putting the pot under pressure you have full control with the valve on the inlet, if you are worried about accidentally over pressurising the pot (max working pressure is 80 psi) you can set the regualtor on your compressor to 80 psi.
The cut off valve fitted can also be used to lower the pressure in the pot if you go a bit higher than you wanted to, whilst the inlet hose is still connected.

416257

Releasing the pressure before opening the pot after the blanks are cured can be done with either valve.

If you are worried about not using the safety valve, you can fit that instead, it can still be
pulled to release pressure. There have been quite a few reports from people that this safety valve is the main culprit for the pot losing pressure over a period of time, so I eliminated it.

416258

I have used joint compound on all joints as well as teflon tape. So far no leaks.

416259

I am now ready to do my first casting and will report on that in due course.

I have made up a 3 tier rack for inside the pot to hold my moulds, although I only have 2 at this stage.
The rack is a fairly good fit inside the pot so it is easy to lower without too much lateral
movement. All shelves are 170mm sqaure with about 6mm cut off the corners. I have fitted a diagonal piece to the bottom which locates it in the dished bottom and a handles for ease of handling. The top sheld diffuses the incoming and prevents it blowing on the uncured resin.

416261 416262 416263 416264

[DJ’s Timber]

Looks good BS, just a word of caution on the air supply side, you may want to fit an elbow or baffle on the inside of the lid as the air blowing straight down onto your moulding trays may cause the resin to splatter about a bit.

[Big Shed]

Looks good BS, just a word of caution on the air supply side, you may want to fit an elbow or baffle on the inside of the lid as the air blowing straight down onto your moulding trays may cause the resin to splatter about a bit.

DJ, I elected to omit that and made the rack do the air diffusion job. If I had fitted an elbow I would have lost 1 shelf. I'll see how it goes, can always make a 2 tier rack and fit an elbow.

[watson]

I'm not a pen person....but this sounds like fun

[PenTurner]

Thanks Fred, deserves a greenie, I will sit down and try to digest this a bit at a time with my pot beside me!:) Amos

[schaf]

G'day Fred,a great report on the pressure pot. Thanks for posting and thanks to Amos for asking.
Fred, you have some very good points there. I left all the gear on the top of my pot. have fitted a 1/4 " fitting to the air intake pipe to accept the air hose. Like you ,I found enough strength to unscrew the paint uptake pipe from the inside of the tank.I do lose a bit of pressure,so take your point and will remove the fittings and use teflon tape and then replace everything. Have also made a rack( not as smart as yours) to defuse the air flow.
If you dispense with the safety valve, what type of fitting do you ask for to screw into the hole.

Have purchased some 4PU polyurthane resin ,white not clear, from Arms Model It in Brisbane.

Sorry Fred ,starting to wander and do not want to steel your post.

terry

[Big Shed]

G'day Terry, I just replaced the safety valve with a 1/4" BSP ball valve as shown in photo 3.

Glad you found my ramblings of some use.

Fred

[salty72]

So B_S what sort of pressures do you expect to operate at? is the pressure just there to expel all the air from the resin blanks??

[Simomatra]

Good stuff Fred, I have been playing with mine as well. I have found that the pot even at 40 psi is not getting rid of all the air bubbles.

[Big Shed]

So B_S what sort of pressures do you expect to operate at? is the pressure just there to expel all the air from the resin blanks??

The reading I have been doing suggests 25-60 psi.


Good stuff Fred, I have been playing with mine as well. I have found that the pot even at 40 psi is not getting rid of all the air bubbles.

:DAt your age too!:D I think the secret is trying to avoid bubbles in the first place, ie don't stir too vigourously, stir without introducing too much air. Then let it sit long enough for the bubbles to rise to the surface before pouring.

Mind you all this from reading other people's suggestions, I have just done my first 4, mainly worthless wood type casting, so we will see.

I am using PR (polyester resin), haven't used PU (polyurethane). A lot of people using Alumilte (polyurethane) are using vacuum, then pressure.

[dhurrang]

Top Post Big Shed !!! Thankyou.

Any info on the casting trays ??

[Big Shed]

Top Post Big Shed !!! Thankyou.

Any info on the casting trays ??

The moulds, or molds as our seppo friends call them, came from an IAP member, Gadget. They were $US25 each and are made from silicone rubber.

I did look at making my own, and probably will still make some other sizes, but this got me started quickly. Barnes (http://www.barnes.com.au/barnescontact.htm), and other suppliers like them, sell the silicone rubber for mould making.

I will be looking at making some 25x25mm moulds for "worthless wood casting".

Modelmaker (http://www.pensbykris.com/molds) in the US makes a mould for this purpose as well, but it is quite pricey and with shipping it would be cheaper to make my own.

[salty72]

when I was in the RAAF we used to mix all our resines and then place in vacuume for 3-5 mins. vacuum was nothing huge about 8-10psi ( I realise absolute is 14.7psi -but they tell me that 10 is a long way off)

this would get rid of all air, warming the 2 pack would also help it as it thined it out

[Buzz]

Looks like the perfect set-up Fred. Thanks for sharing, great explanation and photos. This is something I need to get around to doing. I can see a lot of value in it. :2tsup:

[Big Shed]

The pot held pressure perfectly for 24hrs at 60psi, no loss of pressure.

Opened it this morning and had 4 perfectly cured casts, they were very easy to remove from the mould. On visual examination I could find no air bubbles at all, but the proof of the pudding will be when I turn.

The worthless wood casts were not very successful as they had floated to the surface, so must find a way to hold them in place.

The blanks are quite hard but the surface has a sticky feel to it.

[DJ’s Timber]

:worthless:

[Big Shed]

:worthless:
OK, I can take a gentle hint as well as the next man!:rolleyes:

1 Here are all 4 blanks as they came out of the mould. They came out of the silicone rubber mould very easily, no mould release was used, and it is certainly not needed.
From left to right experimental cast with something called Crystal Shred from one of the $2 shops, 2 wothless wood Red Gum blanks (Sierra size), bark from Red Iron bark showing my spacers to keep it off the bottom of the mould (it floeated to the top with the bark!) and another one showing a different view.

Please note that I used the std Casting resin here, not the water clear one. It has a distinct greyish/purple colour cast to it.

2 The bark of the Red Ironbark

3 Crystal Shred blank, it appears to be shredded foil, black and gold.

4 The 2 Sierra size Red Gum blanks

Lessons learned:

Don't cut blanks too small for worthless wood (WW) casting

Better method needed for keeping WW blanks in place in the mould

Take 2 coming up tomorrow.

Anybody know how long before I can turn the Crystal Shred blank?

[DJ’s Timber]

Looking good BS :2tsup:

In regard to the wood floating, cannot remember who it was but on one of the USA forums, one of the guys who did snake skins used a square block on the ends with I think some weight in the tubes. Obviously this method would required you to drill and glue the tube first, but would this help to over come your problem? I'll see if I can hunt up the link.

[DJ’s Timber]

Here we go, it was Don Ward from IAP I was thinking.

http://content.penturners.org/articles/2006/tn_snakeskinblanks.jpg

This is his Tutorial (http://content.penturners.org/articles/2006/snakeskinblanks.pdf)

[Big Shed]

Thanks DJ:2tsup:, I actually have that article in my pile of stuff I have been reading on casting.

I have just come in from the shed and have cut that Crystal Shred blank and drilled it for Cigar tubes, will try to turn it after lunch. Cutting and drilling went fine, no problems there, so it seems to be cured well.

On the WW casting, I have been reading some other articles as well and have decided to have a go at a modified method. I don't really want to cast the tubes in, mainly because I have to make up my mind before hand which pen I'm going to make. I can see that this needs to be done for the snake skins though.
I am going to cut some square bits of wood just slightly larger than my silicone mould, say 20mm square, then glue these to the end of a 17mm square blank. This will then give me 1mm clearance around the blank for the resin, the 20mm square wood bits will give me tight fit in the silicone rubber and hold the whole lot in place.

To be continued...............

[Big Shed]

Well that couldn't be called an unqualified success. Just turned the Shredded Crystal blank on a couple of Cigar tubes, and the result looks more like varicose veins than an interesting pen blank!:(

Obviously need more of the stuff in there and some pigment to hide the tubes, or paint the tubes.

The Shredded Crystal on its own look very sparkly, but that effect has been almost totally lost by incorporating it in the resin cast.

Oh well, at least I know that the casting process produces a blank that is easy to drill and turn, sands and polishes very well too, although the blank here hasn't been fully polished yet (and won't be!:rolleyes:)

[Buzz]

"Oh well, at least I know that the casting process produces a blank that is easy to drill and turn, sands and polishes very well too, although the blank here hasn't been fully polished yet"

And that the main thing. Won't be long before you have a whole range of amazing blanks:2tsup:

[dhurrang]

Oh well, at least I know that the casting process produces a blank that is easy to drill and turn, sands and polishes very well too, although the blank here hasn't been fully polished yet (and won't be!:rolleyes:)

Nice Blank BS. Why aren't you going to finish it? Maybe a bit unbalanced with the veins but I think would still make a nice pen. Do you have a good supply of spare tubes?

And interesting mandrel. More info please :D

[Big Shed]

[QUOTE]Nice Blank BS. Why aren't you going to finish it? Maybe a bit unbalanced with the veins but I think would still make a nice pen. Do you have a good supply of spare tubes?

Yes, I always buy extra tubes for any kit I buy, in this case Cigar. I will keep the blank on the tubes to remind me of my first attempt, it will go in my "not quite" box:2tsup:


And interesting mandrel. More info please :D


I reported on the ER25 collets here (http://woodworkforums.com/showthread.php?t=72008&highlight=er25)

This set up with a 12mm collet is ideal for the closed end mandrels from Arizona Silhouette. The collet you see here is a 7-8mm for the B mandrel, I also have a 6-7mm collet for the A mandrel.
Am buying two more MT2 chucks so I can keep the 3 most used collets permanently in each.

I also have a MT3 chuck for the new metal lathe coming on Wednesday:2tsup:

[schaf]

Fred, I can not see the veins,but if they are there,why not fill them with colored expoy.
Good first go,well done.
I took your advice and put teflon tape on two threads that where only finger tight. This made a big improvement. Now from 60 psi I lose 5 Psi over 14 min , I can live with that as the polyurthane resin sets solid in about 15 min.

I see that sam is cranked up also, and Amos has a pot,there must be others lurking also or allready casting, very soon we will need a separate casting forum.
Regards

Terry

[Simomatra]

Good start Fred.

I will get around to posting my first attemps later today some good some bad I used the wrong pigment at first and the resin I used set white and took the colour out of the resin.

New stuff on the way from Barnes.

[PenTurner]

Wow Fred, I am still reading the instructions! But you made me laugh with the "varicose Viens", Amos:):D:2tsup:

[dalecamino]

Very good effort Fred ! Looks like you're on your way . :2tsup:

[Big Shed]

Thanks for the comments guys!:2tsup:

As promised, I had another go at WW casting, this time I cut 20mm square bits of waste wood, cut the WW blanks to 17mm square (mould is 19mm square) and glued the square bits of wood to the ends making the whole assembly a push fit in the silcon mould with roughly 1mm clearance all round.

As the photo shows, this was a resounding success.

The one with the bit of wood in the middle has 2 Sierra size blanks glued together, to be cut apart before use, likewise the bits of wood will be cut off the ends.

All I have to do now is turn some of these to see what they are like underneath that resin.

[Big Shed]

And another lot of blanks from the pressure pot. As Sam said somewhere else, this is as addictive as pen turning!:o

Decided to do some experimenting with solid colour pigments, the 2 in the middle are white with some Pearlex 651 Pearl White added, doesn't show up in either the photo os the blank, so we will see. The other is straight Black.

Far left is my attempt at making an M3 looking blank, second from left is White and Black poured in the mould simultaneously.

Second from right is Gold and Dark brown poured in the mould simultaneously, OK if you are a Hawks supporter I suppose. Far right is the remaining Gold and Brown mixed in one cup and some of the Pearlex 651 Pearl White added.

Reserve my judgment till I have turned some of these.

There is another lot in the pot ATM, there I have gotten more adventurous.

To be continued.............. (where is the Days of Our Lives hourglass smilie?)

[dalecamino]

BRAVO Fred !! Can't wait to see what's next . These are all very nice . I believe you're on to something here . Good investment . :2tsup::2tsup:

[salty72]

WELL.... "Show me the MONEY!!!" as Tom cruse would say ... You can't post photos and leave us hanging.... we need to see em turned.... Don't worry about drilling em... JUST TURN...

Can you tell I'm excited for you ???

Mark

[Big Shed]

Patience is a virtue!:doh:

Can't do it right with you guys, first it's "show me the photos, or it did'nt happen!), now it's
"show me the money!".

All will be revealed in due course, have been turning the black and white blank this morning, yet to finish it. Had to be careful to have sharp tools as with a bluntish tool you get smearing from the black in to the white. Cutting nice ribbons with a nice sharp gouge and skew, so seem to have the catalyst level about right.

Edit:

OK, have just come in from the shed. Had a minor hiccup, gouge dug in, turned it in to a "design feature"!:doh:
This is the first of the batch that I have turned, have to say it turns somewhat different from the other acrylics (commercially purchased) I have done so far. Turns well but different, if you know what I mean. Nice ribbons, sands well, both dry and wet. The blank itself I am undecided about. I poured both black and white in to the mould at the same time, it obvious the white is heavier than the black and formed the bottom half of the blank. The white part has nice black swirl patterns in it. As mentioned above, you have to be careful not to get black smearing in to the white, but sharp tools avoid that.
Happy with the way it finished, used my "normal" acrylic method, that is dry sand with 320 and 400, then wet sand 600 - 2000. Then polish on mop on lathe with White Diamond at top speed, then polish with auto polish. Although not that obvious in the photos, it came up up to a high gloss. Not sure whether to turn it in to a pen (Cigar), undecided about the pattern in the blank and the "design feature" I suppose I could call this blank Yin and Yang.

[Simomatra]

Coming along just fine Fred. i have been watching the video's you recommended great stuff. Nice sharp razor tools are the way to go.

[ss_11000]

cool stuff:2tsup:

[NewLondon88]

OH yeah.. that works:2tsup:

I was wondering about the half and half, too. I like it, but sometimes you want it and
sometimes you don't.
I notice the pigments can sink, some colors more than others so I wonder if it
has anything to do with timing? Does the resin have to start setting to a certain
point before mixing? If using two colors, do you need to wait before mixing the
two batches etc.. Don't know, but it makes for some interesting blanks!

[schaf]

Hi Fred,

I think the white side looks very attractive,cannot see the other side as well.
Mixing colors will be art all of its own. A big learning curve before us all.

Terry

[dalecamino]

Very nicely done Fred ! There must be a way to balance the colors , but I'm sorry I have no clue . Great work ! :2tsup:

[Big Shed]

Latest batch from the trusty pressure pot.

These have all been post cured for 30 mins @ 100C in the new toaster oven.

From l to r

2 Oats blanks, the start of a new project, The Breakfast Series!

Powdered slate with pearl

White Pearlex (651) from Barnes with glitter from Spotlight added

2 colours glitter in tubes from the market (5 for $1, 2 tubes used in this blank)

Another try at Crystal Shred, this time cut up with scissors and added to the resin, then poured in to the mould, rather that the stuff put in the mould and the resin pured on top.

2 more straight blacks, a similar mix to this was used for the Chrome Baron FP I just posted.

Now assembling more breakfast cereals, as well as starting on another themed series which will be revealed tomorrow.

Like Sam, I am having fun!:2tsup:

[ss_11000]

those oat blanks look pretty cool:2tsup:

[schaf]

Fred, I really do like the pinks and the black. But then they all look great.

What quanitity of resin did you buy and how many blanks do you expect from it.

Terry

[Simomatra]

Nice work Fred the oat ones look good enough to eat. Looks as if you are getting plenty of shed time.

[wheelinround]

Fred I knew I should have read this from the start great work I gave away a pressure pot 15/20ltr one :roll: well they fella was restoring Mustangs.

To save on wasted resin why not get lengths of tube and set up so they are molded into the resin no glue up worries then :; plasticine in the ends will stop resin from entering but may still need a quick drill/ream.

The look of all the blanks are :2tsup::2tsup:

[PenTurner]

Well, I had the self same pressure pot in its box, brand new sitting for over 6 months, just waiting to make time to get it done, and at the pen show Fred said to me, "It's Easy!" so I took the plunge last night.:?
1. Remove the fittings off the lid, the top ones are easy the big pipe difficult!??
WRONG. Tried first small fitting barely could budge it, after 30 minutes get on the phore to Fred,"are they left hand or right hand threads?" Right hand!, ok I am doing the right thing but won't budge, I reckon the locktite or red stuff has frozen solid.
Sneak into the kitchen, put on oven gloves, get my spanners ready, light the gas stove and heat the joint and fitting, and you beauty, one off. do the other fitting the same way, done. Now for the big air pipe under neath, heat the joint really hot, race out to the vice hold the pipe in vice and turn the lid--piece of cake.
2. Assemble the fittings as per the pictures Fred shows and explains, but I get so confused that I don't know if I am Arthur or Martha,:? it is late now, so photo the pieces email them to Fred, so the phone rings and he talks me through it--oh! that is what it means:-:-, ok tomorrow I go to Bunnings to get the parts needed.
3. Today is yesterday's tomorrow, a Bunnings I did go, and go, and go and go!:((,
First up get the specified fittings, race home and put all together then go to put the adapter in the large hole, no go, too small!? the packet looked a little open at the cardboard maybe someone had swapped it, off to Bunnings and get another, go home, same thing?:?
Then I note the the fitting supplied is not the fitting it should be, the writing is correct but the wrong fitting is in the box! off to Bunnings and explain that to a none to bothered assisstant. Purchase two fiitings to make my own adapter, BUT, the fitting is labelled wrongly also, the 3/8" to 3/8" male thread is labelled 1/8". Duly inform the non preturbed assisstant! away I go make my own tadapter and that is good one side done.
4. Now the other hole, put the meter and the stop valve on the T piece but they hinder me from screwing it on to the hole, so I screw in a male to female 1/4" adapter to raise the height but the T piece won't screw on to the adapter, maybe it is cross threaded,
Grab the T piece and get in the van and start going to Bunnings!!!, but 100 metres from home i had an idea, If i diassembled all the work i had done on fitting the trappings to the T piece, and screwed the T piece in by itself, maybe it would work. Yes, the T piece has a slightly different thread than the adapter I used, it screwed straight into the lid no problems, then bit by bit re did all the work I had done previously, and there was the second part all fixed up.
5. Prepared the lead for the compressor no problems.
6. Put the lid on Compressor and started up, BUT, no pressure build up:? , Ring Fred, !! he doesn't know nothing:D! suggest soapy water to detect if any leak.
Done! top part is beautiful, no problems. Turn the pot upside down resting it on the handle and balancing it, tip soapy water on the under lid right round and turn on compressor, you beauty! a bubble machine for the grandchildren:((,
Ring Fred:oo::oo:! "Is the seal in?" WHAT SEAL???, none? Brand new but NO seal, now it looks like a trip to Super Cheap Auto??
The Photos show some of the careless inaccuracies of the manufacturers.
But really, it is all Fred's fault! He made me do it! Amos:)

[Big Shed]

Mornin' Amos, quite a journey there, life really shouldn't be that difficult!

I hope that today you will obtain the missing seal and that you can finally start to use do some casting.

Good job:2tsup:

[BoomerangInfo]

Welcome to the casting craze :) I left the feed pipe in mine, and just work around it - you never know when I might need a paint pot for actual painting :) Mine still loses a little air, as there's one connection that I can;t put thread tape on due to the design, and it leaks there, but it's not significant enough to stop the process working fine - I haven't hit an air bubble since I started using the pot.

My big pigment order finally arrived this week, but the darn weekend's almost over and I've only just got into the shed! :(

Russell.

[PenTurner]

Here it is, I had recorded my receipt number in Quickbooks, so that is all I needed, the people at SuperCheap were very helpful and opened up another box and took the seal out of that, I told them to sell that one to another pen turner!!:oo:, Well i fitted the seal and there it is holding pressure, now comes more organising to get to casting. Thanks Fred for all your help and input, if anyone else needs help I will send them to Sam or Russell or USA but not Fred!!!:D:D, seriously, you have gone out of your way to help me, hope I can repay that favour with some excellent blanks. Amos.
PS, Russell, like you, my weekend is almost over now, but I learnt a lot from yesterday about Quality and aiming for excellence at all times; Yesterday could have been accomplished in one hour, if the fittings sold to me had been the correct ones. All to do with care in producing our goods. Amos:)

[MarcelloB]

Posting a reply to bookmark this thread. I will need it next time that pressure pot is on sale down at supercheap.

[Squidhead]

Supercheap have pressure pots on sale in their cattledog at the moment $149.40, on sale til 19Jun

Johno

[Sawdust Maker]

another thread where the photos have disappeared

[WOODbTURNER]

Re SuperCheap pressure pot. If you want to remove fittings and suction tube under lid easily, just heat with a gas torch to soften the gunk they use to air proof fittings. Sorry if someone has previously mentioned this.

[Squidhead]

I have been keeping my eyes peeled for the price at Supercheap to come down again, but this afternoon I believe I scored the bargain of the century.

I decided to search good old Gumtree and as luck would have it, a pot popped up.

Being sceptical at first I went for a look, and to my surprise I scored a brand new steel 10+L pot (that I can barely lift) with a pressure rating of 90psi. The pot is brand new and was sitting in the guys workshop for a few years. He decided to get rid of it and I got an absolute steal @ $80

Now the learning adventure of casting begins

Normally I am not overly patient, however today I learnt that it does actually pay off some times.

Happy Days

Pics to follow

Johno

[dai sensei]

..with a pressure rating of 90psi....

Johno

The working pressure is the rating to which you pressurise the pot, just make sure the 90psi is not the ultimate pressure before you go that high.

[Squidhead]

Thanks for the heads up dai sensei, appreciate it. The decal lists the maximum working pressure at 90 psi.

So to excuse my ignorance here, would I be correct in thinking I could pressurise to 90psi on the gauge (in theory, I don't think I would ever need that high surely)? Just trying to get it right in my head from the beginning :-)

Here is a pic

[dai sensei]

So to excuse my ignorance here, would I be correct in thinking I could pressurise to 90psi on the gauge (in theory, I don't think I would ever need that high surely)? Just trying to get it right in my head from the beginning :-)

Looks like a good unit. Yes you can pressurise to 90psi if that is the working limit, and I would, the higher the better is best when casting.

[Necromancer]

Going to strip this and get it set up.
449065

Looking forward to a few pen blanks for a start to get the feel of it, then I think I am going to have a dash at a dragon ball!

[Necromancer]

Change of plans. This Star S770 only goes to 30PSI. Dammit - now looking for another pot.

[Necromancer]

Okayyyyyy,

Went to pack up the above pot to return it to my father - behold, this was inscribed on the lid:

449284

The instructions talk about operating at 35PSI - the lid states not exceed 80PSI.

Safe to use as a pressure pot?? Opinions?

[Necromancer]

Tumbleweeds.

lets see if I get a reply now, I have one of the Supercheap units, trying to figure out what size elbow to put under the lid. Anyone?

[Treecycle]

Mine is not a Supercheap unit but I think they are all pretty generic. I assume you are looking at putting the elbow inside so the air doesn't go straight down and displace any of the resin. On my unit the socket in the lid is 1/8" BSP and elbows are not real common in this size (at least not from general hardware anyway). What I did with mine, probably because I had one on hand was use a push-in tube connector and drilled a couple of holes in the hex part for the air to get out. I just cut the thread off a 1/4" or 6mm bolt and pushed the plain part of the shank into the connection.
On mine the outside part of this socket where the regulator screws in is 1/4" BSP so it actually steps down to the inside fitting. In the first photo you can see the difference between the inlet connection and the outlet/dump connector. The outlet is 1/4" BSP.

486814 486813 486812 486811

[Necromancer]

So finally today I got to the bits and pieces and put it all together. Talk about taking time. The pressure relief valve kicks in at 45PSI for some reason so will consider replacing this maybe. I found that one of the cast right angles that came with the pot actually has a very small crack which releases a small amount of air.

So now to find where to source measuring cups, release agent, and some HPE to make some molds.

The journey has got underway!

[dai sensei]

Okayyyyyy,

Went to pack up the above pot to return it to my father - behold, this was inscribed on the lid:

449284

The instructions talk about operating at 35PSI - the lid states not exceed 80PSI.

Safe to use as a pressure pot?? Opinions?

What you have is a cheap pot, I'm not sure, but the 80psi may be at what point it goes bang. Be very wary of using high pressures, when the pot goes it is a bomb and shrapnel will go every where, it can kill you easily. There will be a reason it talks about a working pressure of 35psi, probably an additional safety factor to allow for cheap manufacturing. This types of pots also have no seats for the hold downs, and are known to fail from fatigue.


So finally today I got to the bits and pieces and put it all together. Talk about taking time. The pressure relief valve kicks in at 45PSI for some reason so will consider replacing this maybe. I found that one of the cast right angles that came with the pot actually has a very small crack which releases a small amount of air.

So now to find where to source measuring cups, release agent, and some HPE to make some molds.

The journey has got underway!

The pressure relief valve setting is associated with the working pressure the pot is made for. 45psi sounds reasonable for a 35psi working pressure. You could take the risk and go for a 50psi working pressure and a 60psi pressure relief valve. You'd need to carefully read the specifications for the pot and decide how much risk you want to take. 50psi is heaps for pens blanks and small items. I only go higher for large bowl blanks etc.

I have an very old cast aluminium pot that I have set up for 50psi woking pressure and 60psi relief valve. Design wise I know it can take higher, but I reduce the pressure I'm working with, to allow some extra safety factor for old age fatigue in the casting (old cast pots like this are known to fail that way). In additional, I tend to cast last thing in the arvo/night and I set up all my pressure pots in the shed and close the door whilst it pressurises. That way before it gets to the maximum pressure and if it's going to go bang I'm well away from it.

Stay safe

[Necromancer]

Cheers Neil.

Going to get the bits and pieces, I think I'll just see how 40 to 45 PSI goes with this one.