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View Full Version : What I did this weekend.. part 2



irving2008
12-09-2010, 08:33 PM
This is sort of a CNC related project... all will become clear eventually... some of this I did last couple of weekends... the last bit I did today...

First take a propane cylinder... empty of course... got three for nothing on FreeCycle...

check its empty, then remove the valve and fill with water... leave for a week or so...
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about 350mm up put a length of masking tape round the cylinder and mark a line using a pencil taped to a bit of broomstick in true DIY fashion!
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Attack it with an angle grinder and cutting disc... a 115mm B&Q 500W one will burn and die before you've finished, so Screwfix came to the rescue with a 230mm 2000W one on special offer for 30 delivered next day... goes through 4mm steel plate like a hot knife through the proverbial butter...
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In the bottom 65mm from the centre, cut a 22mm hole (tricky without a suitable hole cutter and being a budget project I wasnt going to buy one... so drill 5 holes and finish with a rotary file... its going to be out of sight so the finish isnt critical nor is the diameter!)
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In the side, just above where the base finishes, cut a 38mm hole. The hole needs to be tangential to an imaginary 150mm tube in the middle of the cylinder, so I set it up on the mill table with the centre of the hole offset so that the outer edge would be tangential. This is a bit more critical so use a hole cutter. Fortunately I had a couple of them, the B&Q one lasted 1minute and is only good enough for cutting blancmange, the Bosch one fared a little better and finished the job but is pretty useless now :cry:
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Finally remove the centre section of the top to about 80mm diameter. I did this by clamping the top upside down on the mill table, drilling round the weld that holds the valve boss, then cleaning it up with a boring head.
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Total cost so far ... NIL... and only a small amount of swearing :lol:

Next couple of weeks.... what to do with the following...

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John S
12-09-2010, 10:15 PM
Looks like a furnace.

I cut one up a while ago and made this.

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It's a barrow for holding large armatures and rotors.
Problem I have is space, when they unload these and they are on a sack trolly they are two wide to go thru doors and past machines, some of these puppies can weight 3/4 of a tonne.

Soooooo get them to lie front to back, cut this propane bottle up with a small angle grinder and those 1mm thick cutting disks, if you have never used them before, once you do you will never use the normal ones.

irving2008
12-09-2010, 10:29 PM
Yep thats exactly what I used.... bought a pack of 5... made short work of the bottle and a few lengths of angle iron.... mind you you need a powerful angle grinder for these bottles, they are 3 - 4mm steel (at least mine is)... the 500W B&Q grinder died spectacularly in a plume of blue flame that shot out at least a foot!!!

GeorgeD
13-09-2010, 12:27 PM
all will become clear eventually.

Yep,its the Ron Reil style furnace...prettymuch like mine...using a calor gas bottle.

To get a pefect line round the bottle for cutting its head off I used me belt that keeps me trousers up...whipped it round,buckled it and straightened it up level,then felt tip pen around the belt edge.

Whats with filling it with water,Irving?

On a safty note to who may follow this for melting Aluminium?....

Do not attack it with a grinder unless you know it free from gas,even if the gas is burned up do not still attack it as the pressure is still there in the bottle.

To safely cut its head off....

Burn off the gas in a mobile calor gas fire and wait for the flame to go out,disconnect the bottle and also disconnect the hose from the fires connecting valve take the bottle outside and connect the valve to the bottle, switch the valve to the open position as you would if it were connected to the fire,leave for a few hours or overnight to disperse any pressure in the bottle then safely you can remove the brass valve from the bottle with a spanner and commence cutting. SEE WARNING BELOW (http://www.mycncuk.com/forums/showthread.php/2344-What-I-did-this-weekend..-part-2?p=16668&viewfull=1#post16668)

Irving,have you made a flame thrower head yet?this is really important for maximium heat.

BillTodd
13-09-2010, 12:49 PM
Whats with filling it with water,Irving?

To make absolutely sure there's no explosive gas in it. !!!!

Leaving the top open over-night (or even weeks), as you suggest, will not vent the gas properly and could even lead to a very dangerous explosive gas/air mix in the bottle.

GeorgeD
13-09-2010, 12:52 PM
Well there won't be once the valve has been removed and depressurised. :lol:

John S
13-09-2010, 12:55 PM
What about the gas left in that's at atmospheric pressure ?
Unless you vacuum a cylinder or use something to displace it then the original product can still stay in there.

GeorgeD
13-09-2010, 01:02 PM
I've done it the way I explained above...burnt off the gas,reconnected valve off the fire and left it overnight in the open position to depressuise,the hardest part was shifting the bottles valve,stuck solid it was with the bonding putty they use to seal it good style.

Still here,John...no ones house had a valve passing through their window. :smile:

BillTodd
13-09-2010, 01:06 PM
Well there won't be once the valve has been removed and depressurised. As John says, there will be gas inhttp://www.mycncuk.com/images/smilies/icon_lol.gif the bottle unless something displaces it (even a vacuum pump will not remove all of it) . when air gets in through the open valve (it will get in as the air pressure/temperature changes) the result will be an explosive mix

IT COULD KILL YOU (or some other who's stupid enough to take your advice)

To cut open a gas-bottle (or any fuel tank etc.) safely, do it Irving's way - fill it with water - leave it for a few days to ensure there's no gas trapped in the seams and crevices (and to help remove some of the stink!)

irving2008
13-09-2010, 01:22 PM
I agree with Bill & JohnS - even after a week standing out in the garden the water smelt of propane and there was an oily scum on the surface...

Even venting it will not remove the remaining gas as once it has reached atmospheric pressure there is little interchange of gas with the outside world. The danger then is when it reaches stoichiometric ratio (about 20:1 oxygen to propane) it becomes highly explosive. The water prevents any possibility of this happening. I should have added that I put some washing up liquid in it too to break the surface tension and ensure the water got into any gas filled crevices and gave the whole thing a good shake.

GeorgeD
13-09-2010, 01:39 PM
If there was gas still trapped in the bottle then an explosion would have occured immediatly we remove the bottles valve because the air would have ignited the remaining contents,this bottle has remained in an open state in the back yard since I first mentioned about making a furnace on this very forum two months ago?.

GeorgeD
13-09-2010, 01:47 PM
Anyway, Irving could you feast your eyes over this torch and give it your expertise as to whether a better one could be had?
http://metalcast.boorman.us/reil_1.html

irving2008
13-09-2010, 02:03 PM
Rubbish George... the air would not ignite anything... the mixture of oxygen and propane at 20:1 is highly explosive but wont explode unless its ignited.. by a spark.. its whats known as an explosive atmosphere... the point is that opening the valve will not replace any remaining gas in the cylinder ... gas travels from a higher pressure to a lower one... once its reached atmospheric the flow stops leaving traces of propane in the cylinder unless flushed out by something...

you were just lucky... others might not be...

John S
13-09-2010, 03:13 PM
Personally i feel that Georges post wants deleting on safety grounds alone, never mind about anything else.

GeorgeD
13-09-2010, 03:31 PM
EDIT* Remove abusive comments.

Lee Roberts
13-09-2010, 05:11 PM
I have moderated this thread, John please refrain from attacking people directly like you did.

George, first warning and an infraction served.

George, it’s not up for discussion. We have said all that needs to be said in our previous correspondence to you weeks ago, this is another classic example of what we stressed to you, only this time, its on a topic, that could be very dangerous to others!

Both of you please refresh your memory of the current rules we have on the site:


By agreeing to these rules, you warrant that you will not post any messages that are obscene, vulgar, sexually-oriented, hateful, threatening, or otherwise violative of any laws.

The owners of MYCNCUK reserve the right to remove, edit, move or close any content item for any reason.Play nice or dont play at all, please continue with the orginal discussion.

irving2008
13-09-2010, 05:17 PM
Anyway, Irving could you feast your eyes over this torch and give it your expertise as to whether a better one could be had?
http://metalcast.boorman.us/reil_1.html

I have no expertise yet... I am on the learning curve. However I wont be making it from bits of gas tubing as a) its expensive and b) I prefer to experiment using those designs as a starter for 10. I have acquired some nice lengths of 1.5" steel scaffold pole which will form the basis of mine and a secondhand Silverline torch head like this, which has a 35mm burner and a nozzle to suit and provides a convenient way to attach the feed pipe and has a shutoff valve...

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Swarfing
13-09-2010, 11:38 PM
Irving your burner does not need to be that elaborate. I have been running my furnace for just over a year now mainly to feed my habit of needing large blocks of ali to mill. I first went for an all singing converted torch head. these days i have a length of 6mm tube with a 0.6 welding tip soldered in the end which sits in front of a 20mm tube into the furnace. i can adjust the the tip in and out propped up by bricks etc etc. It's cheap, works wel, i do not need a blower and save a shed load of build time. I keep meaning to tidy it up but what the heck it works.

Swarfing
13-09-2010, 11:39 PM
forgot...i can melt bronze and brass mixes too

irving2008
13-09-2010, 11:45 PM
Irving your burner does not need to be that elaborate. I have been running my furnace for just over a year now mainly to feed my habit of needing large blocks of ali to mill. I first went for an all singing converted torch head. these days i have a length of 6mm tube with a 0.6 welding tip soldered in the end which sits in front of a 20mm tube into the furnace. i can adjust the the tip in and out propped up by bricks etc etc. It's cheap, works wel, i do not need a blower and save a shed load of build time. I keep meaning to tidy it up but what the heck it works.

It int going to be elaborate, just the torch leapt off a table at me on a car boot sale for 2, seemed silly not to, as its an easy way to make the burner. All I need to do is mount it in the end of the pipe, instant burner. No blower needed...

Swarfing
13-09-2010, 11:53 PM
It's funny as you see a lot very expensive contraptions being use when simple air/ pressure and gas mix is all that is needed. Most of this can be done by just moving stuff around. I used to be precise a converted plumbers torch to start with which worked fine. The trouble was not enough air could mix and i set the latest incarnation up to do some trial and error testing. the problem was that it took 2 minutes to find the optimum and left it as is. I go through a lot more disposable crucibles (stainless steel canisters) now only lasting no more that 3 melts but these do last longer than steel pipe.

irving2008
13-09-2010, 11:54 PM
what do you use as a crucible?

Swarfing
13-09-2010, 11:59 PM
Stainless spun steel canisters, still not got round to purchasing a decent one. When you need large they get very expensive. Check out the pound shops and look for the Russian doll principle coffee/ tea/ suger ones. At a pound a go works out much cheaper

irving2008
14-09-2010, 12:01 AM
how much ali do you get in one? must be quite thin walled to only last 3 firings... or your burner is turned up too high!

Swarfing
14-09-2010, 12:08 AM
A good couple of pounds, the main reason is because most of the scrap i melt is extrusion and tubing i add copper to the mix. It makes it better for cutting but as consequence adds to the corrosive mix. A good tip for better quality ali, save old wheels, hard drives or similar. Thanks to a good friend i manage to own a piece of farri (part of wheel), very nice magnesium. be careful though skool boy science will tell you what happens if not done with care

Swarfing
14-09-2010, 12:09 AM
I must think about what i type instead of typing what i think? My grammar is coming across pretty poor

dickieto
14-09-2010, 11:45 PM
Hello again Irving saw this on another site thought it might be of intrest to you http://mikesworkshop.weebly.com/propane-burner.html
cheers Tom...
P.S. I've made a couple of wood burning stoves out of gas canisters.
cut the first one with a stihl saw after leaving it for 2 weeks upside down with valve fully open thinking that propane being heavier than air would all be gone.found out it wasn't when the blade cut into inside,blowing the canister half way up the workshop in a fiery rage!!! breaking the disc on the saw and firing it in all directions..
since then I have used the same method as yourself leaving it upright with garden hose running slowly for a day (no water shortage in scotland:naughty:)have had no problems since
SO BE CAREFULL PLEASE EVERYONE!!!!!
:beer:Tom...

Robin Hewitt
15-09-2010, 11:16 AM
I did much the same thing once when spark eroding the spike out of a 6 pounder cannon touch hole.

No problems until it broke through to the bore when the paraffin I was pumping down the electrode carburated going off with a dull thump.

Wouldn't have minded, but on hearing the hiss and crackle as it broke through I was shining my torch down the end.

No eyebrow loss, just made me jump.

Tried to make it do it again but no luck :naughty:

CNCBlug
16-09-2010, 04:49 PM
I have about 20 faulty hard drives lying around here and been wondering what to do with em....

irving2008
16-09-2010, 04:50 PM
send them over... in about 2 weeks I'll turn them into ingots :)

I have 6 x 8" floppy drives waiting...

Jonathan
16-09-2010, 05:13 PM
Ooh, don't forget about the neodymium magnets in the hard drives, I've got plenty of projects waiting for some of them...

CNCBlug
16-09-2010, 05:28 PM
Oh gosh, I have a lot of them (and have the blood-blisters to prove it) and kept all the platters. They make real nice shiney coasters ......
You want them magnets? I think I could get about 25-30 together (I still have to strip a few). They all vary in size though, so dont know what you need them for.

Jonathan
16-09-2010, 05:51 PM
Blisters, ouch yes...they do nip a bit! Not as bad as the 2"x1"x0.5" monsters I used on my wind turbine though!

Yep, I've been using some platters for coasters too! Seems a shame to melt the platters but I wonder if they're a special grade of aluminium or anything?

I'm intending to make a generator and probably a brushless motor with the hard disk magnets when I've got enough.


You want them magnets?
Yes please! I will of course cover the postage for you, if that's enough?

Swarfing
16-09-2010, 10:13 PM
Watch those platters as most are made of glass these days and they look like aluminium. Gentle bend one in a vise and watch them shatter :-)

Hard disk aluminium is lovely stuff to cut

irving2008
16-09-2010, 10:49 PM
well i went into 4 poundstretcher/poundland/99pShops and couldnt find any stainless steel shakers/beakers... lots of alumnium ones pretending to be stainless steel!

GeorgeD
18-09-2010, 01:47 AM
Hi Irving

Didyou have a look in the kitchen sideofthe poundlands? the sugar,tea,coffee sets are stainless steel as I got a set last year but it wasn't ina pound shop it was in Home&Bargain shop which you might not have in your neck of the woods?the set was 2.99 I also picked up a stainless steel Ice bucket at a car booty for a pound this will be ideal as the crucible because its a lot thicker than those tumblers I just mentioned.

Car bootys are a great source for stainless steel items,seen a teapot and some beakers at the same booty but as I got the ice bucket I figured this will last sometime.

irving2008
18-09-2010, 10:41 AM
yes i looked extensively.. as I said, lots of ali ones but none I defintively say were stainless steel. have a few more to look at today, plus a car boot sale in the morning. No worries, i'm in no hurry as furnace wont be finished till next week at the earliest

hmaki
18-09-2010, 04:10 PM
Have you read this?

Really talented guy!
http://vagdrivers.net/forums/index.php?showtopic=37059

http://vagdrivers.net/forums/index.php?showtopic=39794
(Starts on page 10, but read whole thread. Interesting stuff!)

GeorgeD
18-09-2010, 05:27 PM
Lol,I don't think Irving is contemplating on rebuilding his cars engine? :smile:

That fella has too much time on his hands. :lol:

Jonathan
18-09-2010, 06:04 PM
Could you use a terracotta flower pot for the crucible? There's some 50% off in the Wilko near me...not sure if the sizes were suitable as my mum steered me away too quick!
The hole in the bottom is a bit annoying, but maybe you could plug that with a bit of mild steel. Maybe even just a bolt with a big washer.

irving2008
19-09-2010, 02:00 AM
Have you read this?

Really talented guy!
http://vagdrivers.net/forums/index.php?showtopic=37059

http://vagdrivers.net/forums/index.php?showtopic=39794
(Starts on page 10, but read whole thread. Interesting stuff!)

Yes I have, in fact I posted that last link here (http://www.mycncuk.com/forums/showthread.php/2250-An-interesting-build-sort-of-CNC-related...)3 weeks ago :lol:

irving2008
19-09-2010, 02:03 AM
Could you use a terracotta flower pot for the crucible? There's some 50% off in the Wilko near me...not sure if the sizes were suitable as my mum steered me away too quick!
The hole in the bottom is a bit annoying, but maybe you could plug that with a bit of mild steel. Maybe even just a bolt with a big washer.
I have read that you could use clay pots, so i found one I had in the garden and pointed the blowtorch at it... it cracked... so clearly needs very careful and even heating.... think I'll stick with steel for now, and once I have got a bit more practice in, buy a proper A5 graphite crucible. (thats the biggest i can get in, i reckon, and still lift it out)

GeorgeD
19-09-2010, 12:02 PM
Whats an A5? Irving,is it bigger than this 12oz job?
http://cgi.ebay.co.uk/12oz-Graphite-Crucible-Mould-Melt-Scrap-Gold-NEW-/250007590589?pt=UK_Crafts_JewelleryMaking_GL&hash=item3a359d16bd

irving2008
19-09-2010, 07:10 PM
Yes...if you look in the table he lists 12oz = 32cc = 384g of gold = 53g of aluminium... not a lot of use really...

An A5 crucible is 0.9l to the top, but usable capacity is 0.75l = 2kg aluminium, A6 is 1.2l to the top, usuable is 1l = 2.7kg of aluminium. Actually I can get an A6 in my furnace.

I'll leave as an exercise to the reader to work out why a crucible spec'd as '1kg' size is meaningless info....

John S
20-09-2010, 12:04 AM
I'll leave as an exercise to the reader to work out why a crucible spec'd as '1kg' size is meaningless info....



Is it because you can't use a plastic milk bottle to measure molten metal ?

GeorgeD
23-09-2010, 10:31 AM
I have about 20 faulty hard drives lying around here and been wondering what to do with em....

I know the guy that runs a local computer repairs shop,called in yesterday for some Dual layer DVD's and asked him what he does with the faulty hardives he changes when needed...I bin em...oh could you bin em this way....no problem,here's a box of 140...happy days:whistling: and more when he comes by them.

GeorgeD
23-09-2010, 05:46 PM
Watch those platters as most are made of glass these days and they look like aluminium

Up to now,only found these in the 2.5" laptop HD's none in the 3.5 one's.

dickieto
18-10-2010, 02:49 AM
hi irving ,any progress on your furnace?
cheers Tom...

h4ppy-chris
10-01-2011, 07:51 PM
no more pics and how to's?

irving2008
11-01-2011, 01:45 PM
its coming... work, family and then the weather conspired against me.... it will progress once the weather improves, as I have to work outside on this, there isnt room in the garage...

Dellboy
08-04-2012, 03:57 PM
we used to decomission tanks on brick sites (100 tonners) even after them being filled with inert gas for a month ,when purged they still were explosive(due to gas pockets in the metal we were told ) and any welding mods were done by a guy in a bomb proof suit .
so carefull guys