To Those Using A Pressure Cooker As A Steam Generator

[SHINE]

I've got my hose (HD brake line, got my needle (veterinarian, for horses etc.), clamps, and got my pressure cooker. Are the people using this setup just clamping the hose directly to the main release valve and cranking the heat? Bringing it to a boil & dropping to a simmer?

I hooked everything up, heated it up, and wasn't getting anything from the needle. I cooled it down, depressurized, and tried blowing through the needle to check for any obstruction. It takes what seems like quite a bit of force—more than the little weighted safety cap would allow (I assume). But maybe that's required to force steam out of the rig and through the needle? I'm just a little anxious about building pressure beyond what the gasket can handle... Was thinking of installing a second release valve and using one for the hose/needle, and one for the regulator, but thinking a little harder about it, the steam would release through the path of least resistance first. Maybe an adjustable valve w/ gauge so I can have some idea of the pressure I've built up and regulate the flow?

Ideas? Tips? Thanks.

[George Roberts]

Your system looks almost identical to mine, and I've had no problems with it.  Remember that there is quite a bit of air in the pressure cooker that has to be expelled before you get to the steam.  You could try putting the needle in a cup of water to see if you're getting bubbles.  Once you have steam, you can almost turn the heat off, and the steam will continue for a long time.

[Andrew]

I have pretty much the same rig as well, and it works okay, but indeed due caution is involved  and should not be understated when dealing with this kind of heat and pressure. I have blown the safety release valve on mine when i got the needle plugged once, and lets just say it will wake you right the hell up if you're being lacksadaisical. The amount of steam and heat coming out of the needle doesnt feel like much, but once you out that force in the confined space of a dovetail joint it will heat things up quickly.

I got the stew mac hose and needle (its nice and long and the handle part is well assembled - but i still wear gloves mostly). I also wrapped the hose with insulation so it stays warmer and therefore produces less condensation. I keep it on a hot plate and warm it right up at max for a good ten minutes and do some prep while i wait. You can control the amount of pressure by dialing the hot plate back after initial warm up but it is not very responsive. Make sure you have a good air blower/vac system a la FRETS.COM for around the heel, - you will need it. It would be nice to have some kind of regulator system for the amount of pressure in the pot without reducing the heat, but i personally dont know how to make such a system safely and without collecting more condensation somewhere in the line. The safety plug on mine always bubbles and hisses and doesnt seal well until there is lots of pressure. I control excess pressure by poking it with a screwdriver and venting off excess pressure, but the plug on mine has en extra little button for that which I do not see on yours.

I do nit think that you will blow the lid on your cooker so long as that safety plug is in place correctly, as it is designed to burst before the metal can fail. You do not, however, want to be standing right beside it if the plug does go. Earplugs and safety glasses are also a good precaution here lol. I believe your cooker rig will work fine, but practise warming it up and down and using the steam needle in a campfire guitar and become familiar with what it is telling you. 

[SHINE]

@George Roberts,

Both of your tips helped me out. Needle in water let me know when I had pressure, what kind of pressure I was dealing with etc., and turning the heat right down (after boil/pressurizing) provided me with a nice, predictable, even flow of steam with no drama.

@Andrew,

Thanks. It was good to hear that someone else (who has used it) was also cautious of this rig. I was feeling a little paranoid about it, but was able to get it to work with the tips, knowing what to look out for and be aware of. I really didn't want to burn myself or my helper this way.

Well, it was a success. Once I dropped the heat and got continuous steam (with surprisingly little spit/excess moisture), it took me all of 50 seconds applying steam to soften the glue joint enough to remove the neck, nice and clean (though my fingerboard extension didn't go as smoothly as I'd hoped). This is a nice rig, and pretty safe, especially given the method I followed here. Very predictable and no drama, which I really wasn't sure of before I tried it. Thanks for the replies and the help!

[Andrew]

Yes, once you get familiar with it the process is much less intimidating. Good to see you were successful. Just watch out for tight dovetails that could lock up on you lol...

[onewent]

Glad you had success, steam can be scary .. I popped a hose once, and I just about you-know-what in my pants.

I tried the pressure cooker idea at one point, but couldn't get it to seal, so gave up and went back to the cheap ebay cappuccino/espresso makers..they seem to be good for about 75 neck sets or so the way it's going.  

Regarding your 'bypass valve' question, I put a little brass valve in line with the steam needle and it works well.  I keep it closed until I get good steam through the needle and the hose is hot, then open a bit at a time until I get a nice gentle puff of steam before I insert into the dt.  Keeps things neater, generally, and I can always close it a bit if I want a heavier volume of steam to go into the joint.  

You can see my rig in the pic.

Nice idea to insulate the hose to avoid excess condensation .. What do you use as a wrap?  

Thx. Tom

[Andrew]

I used a roll of fiberglass pipe wrapping insulation and just held it in place with green masking tape. Now its a bright green snake looking thing about 2 inches wide. Its pretty hard to miss which i dont mind at all lol. Especially since Im less refined than you and let mine blow steam at the floor :P. The insulation made a fairly noticeable difference.

What type of valve did you use? Was it anything rated for pressure or just a regular plumbing part? Any particular reason for the S bend in the vent tube?

One more note on pressure cookers as steam generators for the OP: I found the amount of water in the pot had an effect on the steam at the needle. Anything over half full and the steam tended to be much wetter. About 1/3rd full seems to work well.

[SHINE]

Re the 1/3 full, I bought my pressure cooker new—not many used shop options around her for that kind of thing, no garage sales because it's still frozen here). I read through its instructions, and they happened to recommend never filling it past 1/3 with liquid, so I followed those. After the hose steamed through and warmed up a bit, it did produce nice and even, gentle steam. 

I've watched all the videos I could find over the last year or so, and I have noticed a lot more water/cleanup happening in those than I had to deal with. Mine was very minimal, perhaps due to using less water and a lower temp/pressure once it got "primed"? 

[Walter W Wright]

about to dive into this fun stuff myself for the first time (just got my vintage presto pressure cooker off ebay and a customer with an old harmony who's game to be the guinea pig) but the one thing i've noticed in all the tutorials i've read and watched is that nobody covers the nearby finished areas with tape!

that seems like a no-brainer to protect the finish around the neck joint from the stray steam but nobody does it; is it just not necessary or is there an actual drawback, like the steam causing the tape itself to react and actually damage the finish?

[Andrew]

Tape is not sufficient to protect a finish from hot steam. Youre likely to trap more moisture in the finish than without tape... at least this has always been my assumption. Perhaps there is a certain type of tape/application method that would work.. however an air blower rig like I already mentioned definitely works. You can make one pretty easily without spending very much.

I just did a neck reset on a harmony and the finish was pretty soft and it blushed like a bugger on me, just to warn you. The nature of the finish made it very hard to remove. I was able to do so, but it was an adventure...

[SHINE]

Because of all the necessary water cleanup I was seeing in demonstration videos, I just decided to stuff a hand towel in the sound hole around the block and also drape a full-sized towel around the heel and up and around the fingerboard. my thinking wasn't that it would protect the finish from heat so much as that it would instantly absorb escaping hot moisture while still being able to vent excess heat somewhat efficiently. I had a nice slow, even stream of steam though.

[Walter W Wright]

makes sense, absorbing the moisture rather than trapping it

[Walter W Wright]

wow, what the hell?

new stewmac idea, basically a long rod that goes on your soldering iron, gets jammed into a neck joint and heats it up for removal with no water!

https://www.youtube.com/watch?v=HafSxxKPklg