Devil Forge use for a newbie

[David Joiner]

Hi everyone, I'm completely new to blacksmithing/metalwork so I'm sure I'll have many questions over the months/years but my first is regarding the devil forge I recently brought, I'm worried I may be damaging it by the way I'm using it, but being new to this I have no points of reference. Here are three photos the 1st is of the top of my forge after only a few minutes of use (is this sort of charring to be expected?), 2nd the forge in use (does this seem adequate to heat and shape metal with?)  and 3rd the pressure my gauge is showing (is this to low? too high?).

Could someone please advise if this all looks ok.

I thank everyone who take the time to answer me.

 

[Jasent]

You need to ridgidize and seal the insulation with a good refractory cement and if desired an IR reflector like metirkotte or plistex or itc 100.  Go to the gas forges section and read the forges 101 thread. Will save your lungs/ life and a lot of head ache!  

 

My my forge likes 13-15 psi best. Your results may very

[Irondragon Forge ClayWorks]

Converting MPa to PSI it looks like your pressure is on the low side  (0.1 MPa = 14.5 PSI) after sealing the wool insulation try turning the pressure up a line at a time.

What does the burner sound like at that pressure?

[Mikey98118]

Your forge photo shows an excellent flame coming from its burner, which is a problem for you; the reason is that such a flame is not causing the carbon build up on your insulation. Something in the insulation is cooking off. This means that at the very least you will have to turn the forge up hot enough to burn away all traces of this chemical, and the carbon it is leaving on your insulation before you can either rigidize the ceramic blanket or seal coat it.

This brings up the very first thing you must do before going any further. You must move the half brick floor clockwise until the flame impinges on it toward its near edge, rather than on the forge wall. Yes, that means you will have to move the legs too. Why? Becuase otherwise your insulation will not last very long.  So, why right now? Because every time you heat the forge, that insulation takes a set, and that means that if you wait to move the floor, the forge will end up with two permanent creases in the wall, where you don't want them.

[Mikey98118]

You will also have to provide front and back walls for the forge. Don't be discouraged by all this. You are getting good value for your money, but this model cannot be considere a turn-key forge.

[timgunn1962]

I can't see the end of the burner where adjustments are made, so it's not clear whether it's a DFP or a DFPProf burner. I'm guessing it's a DFP?

You have 2 adjustments with the DFP. The first is the amount of gas being burned and this is controlled by adjusting the gas pressure. The second is the flame temperature and this is adjusted by varying the choke position (the disc on the back of the burner that screws up and down to vary the air gap between the bellmouth and the disc).

If you've run with the choke closed, that'll explain the sooting. 

I bought a DFP burner only off ebay, just to see whether they'd done a good job of it and I was impressed. It seems they've got the gas jet (which looks to be a drilled hole) about right, IMO. Mine seems to get hotter as the choke is opened while remaining on the fuel-rich side of stoichiometric even with the choke fully open.

I only did my initial testing in a purpose-designed Heat-Treat forge, so I've not tried for maximum temperature yet. I still need to try it in a "normal" forge to see if it'll get to welding temperatures and it's something to get around to in the next few weeks: I prefer to do in the dark so that I can see what the flames are doing and it is best done in the the dark winter evenings. 

Operating pressures are likely to fall in the 0-0.2 MPa range (0-30 PSI). For a given gas jet, gas flow varies with the square root of pressure.

If you burn X gas per hour at 30 PSI, you'll burn 0.707X at 15 PSI, 0.5X at 7.5 PSI, 0.25X at just under 2 PSI and about 0.18x at 1 PSI.

[Mikey98118]

Excellent post, Tim.

It should be posted in Forges 101, to keep it available after the end of the month.

[David Joiner]

Thank you all for your answers they've been very informative.

I will look at adjusting the angle of the burner and the brick so the flame is on this and not the wall as Mikey has suggested.

And Tim I think your right when you said running with the choke closed caused the sooting. I've been starting it up this way as this is what was said in the instructions, from now on I will start with choke open.

I'll also be reading through the forges 101 section, but have a couple question about refractory cement, should I apply this over the insulation blanket even with the sooting? and are there any specific types/varieties  I should look out for?

Thanks again. 

[Mikey98118]

No; heat up the forge enough to burn the carbon away first. Next, rigidize the ceramic blanket. Then cast the refractory hot-face layer, if you choose to go with Kast-O-lite 30. Or you can roll on a layer of zirconia silicate refractory, or even spread on this formula like plaster. These two are the best choices for a hot-face layer to protect the insulation, both thermally and mechanically.

[Gareth Johnston]

sorry cant help as also new to blacksmithing but great to see another smith from the uk . hope you get your problems sorted ! . Gareth 

[timgunn1962]

Refractory coatings are not particularly easy to give good advice on, at least over here.

I gather Kast-O-Lite 30 is very highly thought of, but it's not very easy to get hold of here, particularly in small quantities. The same tends to be true of Mizzou and most other hard castable refractories.

The blanket is relatively easy to get in "our" quantities, though it's become difficult to find anything less than a full roll of the 1400 degC (2600 degF) stuff since the body-soluble fibre started to become popular. The body-soluble stuff is only rated to 1200 degC as a rule.

My advice is to accept that you are not going to build a forge-for-life anytime soon. You'll need a fair bit of actual forging under your belt before you are in a position to decide exactly what sort of work you are going to need to build it for.

From the OP, it doesn't sound like you'll need welding temperatures for a while yet ("does this seem adequate to heat and shape metal with?")

I'd buy some extra blanket: enough for a couple of reline jobs on the forge you have. You'll want 25mm thick, 128 kg/m3 (1" thick, 8 lb/cu.ft). The body-soluble stuff can be found by the metre on ebay.

I'd then go to the nearest Screwfix, Toolstation, B&Q, etc and buy 2 or 3 x 2 kg kg tubs of cheap fire cement. If you can find some that look like they've been on the shelf since Noah made landfall, get those and don't move them more than you need to. While you are there, get one of those long-handled, angle-head, cheap, nook-and-cranny paintbrushes.

You'll need some containers to mix stuff in. I tend to use 1L yoghurt containers. Whatever you use needs to be sealable, disposable and you'll want a few of them.

If you can find a really fine seive, it's useful too.

You'll also need some stirring sticks, and something to apply a coating of fire cement with. I tend to use bits of 1" x 1/8" steel flat bar because it's what I have. 

Take that bit of hard fire brick out of the forge and put it to one side. 

I’m not sure what the spec is on the blanket Devil Forge use. If it’s better than the blanket you’ve bought, take it out and save it for a reline when you are likely to need welding temperatures. Whatever you get should be fine to forging temperatures.. I usually cut blanket with a knife on a sacrificial wooden board to minimize fibre release. I usually scarf the ends at 45 degrees where they join, though I’m not sure it really helps. I usually cut the burner hole through the blanket with a holesaw, turning fast and feeding slowly, outdoors and upwind of any fibre release. 

Open a tub (container 1) of the fire cement carefully. If you are lucky, there will be a layer of viscous liquid on top that has separated out while it has been on the shelf. Decant this into another container (container 2) and save it for later.

Take about 1/3rd of the remaining contents of the tub (container 1) and transfer it to another container (container 3). Add tapwater, mixing to get a an even consistency until you have about 1/2-3/4 litre (1-1 1/2 US pints) of milky liquid.

Let it settle for perhaps 30 seconds so the bigger (sand-sized) solids settle out. Decant off the milky liquid (through the sieve, if you have one) and add it to the viscous liquid in container 2 that you decanted off earlier.

Keep mixing so it doesn’t settle out while you slosh it onto the blanket in the forge with your angled brush. You'll need to rotate the forge as you do so. The idea is to get the fine clay-like stuff and the resin-like binder soaked into the blanket to work as a rigidizer.  

Don't skimp; you want the blanket properly wet to a depth of 1/4-3/8" (6-10mm), but retain some for later if you can. Some of the solids will almost certainly stay on the surface.

Return the sandy solids and any remaining milky liquid from container 3 to the reamaining 2/3rds of the fire cement in container 1 and mix. Add tapwater if needed until you have a spreadable consistency.

Spread this onto the blanket to get as even a coating as you can manage. Aim for about 3-5mm (1/8” - 3/16”). Thicker is not a problem, but try to save some for later.

Do not coat the end faces: you’ll need a route out for the water vapour.

Put the lids on the 2 containers with stuff still in them and put the forge somewhere to dry. Where you put it will obviously depend on what’s available. I suspect an oven set on really low would be ideal: like you’d use for making jerky. I tend to leave things in my unheated shop and it takes weeks to dry there. I doubt Derbyshire is very much better than Lancashire in this regard, so indoors is obviously better. It’s a case of doing the best you can without causing undue domestic disharmony.

You don’t want to get it hot enough to flash off steam in the fire cement, so a hairdryer is ok to help move things along, but a hot-air paint stripper probably isn’t.

Once it seems pretty dry, you can set about reducing the openings. A 1” wide strip of 1” blanket, soaked in the runny stuff and coated with the thick stuff can be put inside the ends. You can also peel the blanket apart to get a further 1/2” layer if the type of work you intend to do will let you use a smaller opening. Don’t go smaller than your nook-and-cranny brush head, as there’s a good chance you’ll need to patch up the fire cement at some point.

Most of the stuff you’ll see online talks about numbers of burners for forge volume. My experience suggests that the size of the openings has more effect on the amount of burner needed than the volume. Use the smallest openings you are sure will be big enough for your immediate needs.

Put the forge back to dry. The reason for not reducing the openings earlier was that the reduced openings reduce the airflow through the forge and slow the drying.

Once the interior seems dry, you can fire it up at the minimum pressure and choke opening it’ll run at for brief periods. The heat robbed by the drying liner and the water vapour produced will mean that you’ll need more pressure/choke opening than for a dry forge. You can increase the duration of the on periods as things progressively dry. You don’t want to flash off steam in the fire cement. It causes bubbles to form which dry quickly and break off, thinning the layer..

As the lining dries from the hot face, it’ll get to the stage where there’s no danger of damaging the lining and the water still in the blanket will be driven out through the unsealed faces.

While the blanket is drying, you can turn up the burner pressure and open the choke until you have the temperature you’ll need for normal work.

Don’t be tempted to give it the beans just to see what it’ll do.

Make yourself a work support to go in front of the forge. The lining will last much better if it doesn’t have to take the weight of the workpiece.

If you are doing stuff that doesn’t need a rear opening, it can be temporarily closed up with a piece of untreated blanket.

Put your spare materials somewhere safe so that you can reline as and when necessary. Keep the blanket in a sealed bag. Separate marked, sealed bags if you saved the original blanket.

This procedure and these materials will not give you a particularly good forge. What it will do is give you a forge that works well enough and lasts long enough for you to develop the skills and knowledge to decide what your next forge needs to be like. It is cheap/easy enough to reline that fear of damaging it to be unlikely to limit your activities.

[WayneCoeArtistBlacksmith]

David, contact me and I may be able to help you,  You can PM me or send an e-mail.  I prefer e-mail.  You can find my contact information on my profile.

Wayne

[David Joiner]

 

Refractory coatings are not particularly easy to give good advice on, at least over here.

Tim, I think you've done an excellent job here. I waited a couple of day before replying simply because I wanted to get my head around it and ask any questions, but I think this explains it sufficiently.

I would like to thank you for the time you spent answering my questions.

I am getting things ready to hopefully do this over the coming weekend, as its my first time I'm not looking for perfection, anything short of  catastrophic failure.