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Working on that new ribbon forge


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Its comming around. The burner is 320x80 mm, rather brutal. Now for ceramic blankets, 2 layers, then doors and such. I need air regulation, rest of the 2" piping (I have some) and safety solenoid for the gas.  

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Wayne, you remember all the problems our Douane oficialls did when you sent me that IR refractory paint?  WHITE POWDER in a plastic bag?  :D :D :D  I am literary 8000 miles from you.   PS. Regulator, gas tubes and cable is there on the floor.

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And I have used the information from your page to build that burner, except there is not castable refractory in this country, that can be used. What I did is I built a metal form and had a company which does heat resistant pans and stuff to form the whole block for me. And that is screwed to the metal part with some use of HR putty. 

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  • 2 weeks later...

Now the ceramic blanket, hardener, electrification, safety solenoid on the propane line etc.  An mesh on the air intake with some possibility to regulate the airflow.

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Here is some pictures of my forge when I first built. They are not great pics as Photobucket still holds a lot my photos hostage,......... but that is another subject! 

 

My forge has flip up ends. In case I need to re-work the inside it makes it a lot easier. Also that allows me to open up the back so I can work on something that is actually longer than the forge itself Those ends are insulated the same as the forge body itself. They latch with two each suitcase type latches. Something similar too these SARHW38 - 2 Pack of Small Briefcase Style 2 Piece Latches for Guitar Cases - Pro Audio DJ Chest or Trunk Latch Here is a picture with one of the lids flipped up! my forge.jpg What you see in front of the forge is a work rest that can adjust in and out as well as raised and lowered. Also I made the front door with a slide type door that can be raised or lowered to a certain height. That way I can maintain the heat and not loose anymore than possible! forge.jpg It works off a couple of pieces of angle iron I cut down to be just wide enough to let the door slide up and down. A bolt with a T-handle is used to lock it at any certain height! You can see in the bottom picture. Anyway there is my ideas! Hope it helps!

Edited by C Craft
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On 7/17/2021 at 11:56 AM, Jaro Petrina said:

Guys I need some ideas for doors.

 

This is my setup:

 

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Drum pedal is connected to a cable that's routed underneath the forge and connects up to the door's counterweight. Operation is hands free: step on the pedal and the door opens (partially or fully depending on how hard you step on) -- let go and the door closes. The pivot can slide in and out so that the door can sit closer or father from the opening to leave it partially open or fully closed. The door itself is just a soft firebrick that can be replaced when it eventually starts to crumble.

 

 

 

Edited by Francis Gastellu
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On 7/19/2021 at 2:50 AM, Francis Gastellu said:

 

This is my setup:

 

LZjTLjX.jpg

 

5KKucoG.jpg

 

Drum pedal is connected to a cable that's routed underneath the forge and connects up to the door's counterweight. Operation is hands free: step on the pedal and the door opens (partially or fully depending on how hard you step on) -- let go and the door closes. The pivot can slide in and out so that the door can sit closer or father from the opening to leave it partially open or fully closed. The door itself is just a soft firebrick that can be replaced when it eventually starts to crumble.

 

 

 

That looks also workable Francis, thank you.

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Update : the blower didnt survived, the gearbox busted and overheated and leaked oil in 10 minutes. So I bought better centrifugal blower, quite new (!), frankensteined it on, together with air valve, safety solenoid - which closes the gas supply if the blower is not running, switch etc.  The blower is 850 W and should give 85 cfm on continuous run with about 150 mBars of overpressure. i hope its enough. My method of gluing the burner block into the manifold using refractory mortar seem to be working fine.  The square handle can be pulled out and host variety of barstock holders.  My welding is quite bad, I bought the table, that is atrocious, but it was cheap!  It should get mat black high temp paint at the end.  On tommorow I put the ceramic blanket in, then the hardener.  I will only leave about 6 cm hole at the back, should be enough for any sword.  That will be covered by single brick.  I will make two brick door - movable to sides in the front.  Seems like two more days of work or something. Its starting to look like really nice machine.

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Blower specs seem unusual.  85 CFM appears a little light for the size block you have, but 150 mbar equates to 60" WG, which is some serious overkill.  It really all depends on the actual shape of the fan curve, which is not predictable from a  single point of operation (if the data given is even accurate, you need the airflow at a certain total static pressure).  850W is around 1 HP, which should be plenty, so hopefully the curve matches your installation.

 

Not a huge fan of the blue plastic elbows near a forge, or the gas hose on the ground.  I'm sure that will be addressed when you complete your build.  It looks like you have a gas solenoid valve inline which is an excellent precaution.

 

Hope you plan on a lot of insulation.  That is a pretty huge forge interior.

 

My gas forge uses a front door that slides to one side.  Sorry I don't have a photo handy, but it is a cast refractory insulation in a welded angle steel frame on two hangers.  The hangers terminate in pulley wheels from a  garage door opener system and those run on a u-channel rail at the top of the forge.  Pretty crude, but it works well and holds up.

Edited by Dan Hertzson
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Posted (edited)

The blue plastic is silicone for car turbo´s  and its rated up to 260 C continuous use.  Its gonna have double insulation, so the inner space will shrink considerably - Its 50 cm diameter now, and I have insulation 40 and 20 mm.

Edited by Jaro Petrina
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It's a side-channel blower (aka regenerative blower). I love them. I feel they are an order of magnitude "better" for forges than most conventional centrifugal blowers. However, the Pressure:flow curve is unusual.

 

Without seeing the curve for the actual blower you have, my guess would be that the blower can do 85 CFM at zero pressure (about 144 M3/hr), 150 mbar (60" WC, about 2.2 PSI?) at zero flow and that it will follow a curve between these 2 endpoints.

 

If you try to throttle it to get down to the flow you need, you will very probably (perhaps almost certainly, depending on the precise model/characteristics) cause it to overheat.

 

The unusual characteristic of side-channel blowers is that the more they are throttled, the harder they work, the more power they use and the more heat they put into the air that they move. Rather than simply throttling the line to the burner, you are MUCH better off fitting a tee, such that you throttle the burner feed downstream of the tee AND bleed off surplus flow through a second valve off the tee.

 

If you do this intelligently, you can arrange to bleed off the excess air to an air curtain across the mouth of the forge.

 

 

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29 minutes ago, timgunn said:

If you do this intelligently, you can arrange to bleed off the excess air to an air curtain across the mouth of the forge.

Great idea!  Something to remember for my next forge build.

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1 hour ago, timgunn said:

It's a side-channel blower (aka regenerative blower). I love them. I feel they are an order of magnitude "better" for forges than most conventional centrifugal blowers. However, the Pressure:flow curve is unusual.

 

Without seeing the curve for the actual blower you have, my guess would be that the blower can do 85 CFM at zero pressure (about 144 M3/hr), 150 mbar (60" WC, about 2.2 PSI?) at zero flow and that it will follow a curve between these 2 endpoints.

 

If you try to throttle it to get down to the flow you need, you will very probably (perhaps almost certainly, depending on the precise model/characteristics) cause it to overheat.

 

The unusual characteristic of side-channel blowers is that the more they are throttled, the harder they work, the more power they use and the more heat they put into the air that they move. Rather than simply throttling the line to the burner, you are MUCH better off fitting a tee, such that you throttle the burner feed downstream of the tee AND bleed off surplus flow through a second valve off the tee.

 

If you do this intelligently, you can arrange to bleed off the excess air to an air curtain across the mouth of the forge.

 

 

 

Thank you Tim, I already found out its not easy to throttle it down. I can indeed fit a second valve to the main to bleed excess air. Another option would be frequency changer, but Its 850W, so at least 1000W changer and that is expensive.

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If it's 3-phase, and particularly if it can run on 230V 3-phase (where is Hobbit country by the way?), I'd be inclined to run it on a VFD. I tend to build my VFDs into IP65 enclosures with sockets on for things to plug into, so one VFD can run several different machines simply by plugging the appropriate one in. The controls are on a long cable, so I can move it to the appropriate machine. 

 

It doesn't make the VFD any cheaper, but it's a lot easier to justify the expense if it's something you can use for multiple purposes.

 

The 

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Sorry: fat fingers.

 

The bleed-off-excess-air method will work fine though. It just "feels wrong" bleeding off the majority of the air that you are compressing without doing anything useful with it (which is why I mentioned the air curtain).

 

I don't think I've seen a real gas forge actually using more than about 18 CFM of air, which, if my calculations are somewhere near the mark, corresponds to between 5.5 lb/hr and 8 lb/hr of Propane use, though I'm sure some of the guys with big power hammers exceed this.

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"The bleed-off-excess-air method will work fine though." - I have already installed the bleed out ventil its the cheapest solution. It would be an equivalent of 200 bucks for VFD vs 30 for ventil. Hobit country is bohemia off course :D

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Another cheap option, if you don't mind plastic piping, is to use a 3 port 2" swimming pool diverter valve.  This will proportion the air between the two paths with operation of only one handle:

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Looks good Jaro. 

 

The 3-port diverter should work too, but I think the porting on these is usually set up to keep the combined area of the port openings fairly constant, which might limit the ability to throttle the flow and increase the backpressure. I don't really have much experience of those valves though.

 

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1 hour ago, timgunn said:

Looks good Jaro. 

 

The 3-port diverter should work too, but I think the porting on these is usually set up to keep the combined area of the port openings fairly constant, which might limit the ability to throttle the flow and increase the backpressure. I don't really have much experience of those valves though.

 

 

Many thanks Tim.  I have meanwhile used hardener on ceramic blanket and painted the inside with a refaractory paste. With bit of luck I will paint the forge body black with high temp paint and put it all together on tommorow, altough I might need it rest for couple of days to dry, before I fire it up.  The inner space is rather big, like cylinder 50 cm long and 32 cm in diameter. But I have learned from my previous forge that the space should be proportional to the burner. 

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I know it's probably not necessary, but I'll say it anyway: dry it out properly before you fire it up.

 

Depending on the "refractory paste" you have used, this can take from "a bit longer than you'd expect" to near-geological time. The worst stuff I used was a readily-available "refractory cement", which I assume was actually clay-based. After a couple of days I thought it was dry enough, but it wasn't. On first firing, the surface dried out pretty much instantly, the moisture behind it flashed to steam and lifted the surface as bubbles. These broke and flakes fell off, then the process repeated. 

 

For the little forges (made from a 12" length of 8" pipe, 300 x 200mm, lined with a double layer of 1", 25mm, blanket), it was maybe ten-bucks-worth of useful learning experience: pretty good value in my book, and better value still if it helps anyone else.

 

After that, I dried my little forges in the oven (on the lowest setting, like drying beef for jerky), risking the wrath of She-Who-Must-Be-Tolerated. Yours seems too big for that, so the incandescent light bulb inside, or similar, might be prudent. 

 

Hydraulic-setting refractories shouldn't be as bad, but can still crack quite badly if they are wet enough to flash off steam.

 

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12 hours ago, timgunn said:

I know it's probably not necessary, but I'll say it anyway: dry it out properly before you fire it up.

 

Depending on the "refractory paste" you have used, this can take from "a bit longer than you'd expect" to near-geological time. The worst stuff I used was a readily-available "refractory cement", which I assume was actually clay-based. After a couple of days I thought it was dry enough, but it wasn't. On first firing, the surface dried out pretty much instantly, the moisture behind it flashed to steam and lifted the surface as bubbles. These broke and flakes fell off, then the process repeated. 

 

For the little forges (made from a 12" length of 8" pipe, 300 x 200mm, lined with a double layer of 1", 25mm, blanket), it was maybe ten-bucks-worth of useful learning experience: pretty good value in my book, and better value still if it helps anyone else.

 

After that, I dried my little forges in the oven (on the lowest setting, like drying beef for jerky), risking the wrath of She-Who-Must-Be-Tolerated. Yours seems too big for that, so the incandescent light bulb inside, or similar, might be prudent. 

 

Hydraulic-setting refractories shouldn't be as bad, but can still crack quite badly if they are wet enough to flash off steam.

 

I am thinking of leaving it week or two just lie around and then use heat gun to dry everything out.

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