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Normal Topic A gas fired knifemaking forge (Read 440 times)
Von Gruff
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A gas fired knifemaking forge
Mar 14th, 2017 at 5:35pm
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I got another batch of knives heat treated today and it reinforced the notion that I needed a better way to do it than in the kitchen fire. I had been looking at gas forges for a couple of weeks and decided to build one for myself. There are a couple of good videos of how to make them from the 20lb gas bottles so when I was in the city yesterday I went to the metal scrap yard but the only gas bottle on the yard, had the top cut off it but there was a stack of lazer cut 10 3/4 in dia x 3/16 discs there so I got two of them as well as a length of 1 inch black pipe for legs.

This is the bits I bought home.



So the first job was to grind the opening out a little to fit the plate which was a simple mark and grind.



I decided to do the bottom as well because when they were doing them on the youtube it seemed like a bit of a chore to make the insulation conform to the semi rounded shape so I figured that a flat surface woudl be easier.



  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #1 - Mar 14th, 2017 at 5:40pm
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Then it needed a little clean up to make sure the plate fitted nice and flat. A friend just down the road welded the plates in place for me, so that all needed a clean up. I gave it all a good going over with a heavy flapper disc on the grinder to get rid of the old paint and the bit of surface rust.



I set it up with a couple of blocks to hold it still and make sure it was more or less secure for the marking out of the next step. Having the flat plate on the ends made this easier so I was pleased that I hadn't started with a complete bottle for a start as I might have had to do it on the curve surface.
Finding the center of the plate both verticall and horozontally was a simple matter, so after leveling the line accross the front (and rear as well) I was able to do the vertical which allowed me to mark the top center mark where the handle will go.



I have seen various measurements for the offset of the gas inlet from 10degrees to 30 and as the idea is to make the gas swirl round the inside of the forge I went with 25 degrees. Marking a square on the board and a 25 degree line in, I could go up the line by haf the dia of the bottle and get the measurement away from the center line that would give me a 25 degree offset.



So that can be marked on the top of the bottle ready to be drilled for the gas inlet.



That is where it will have to sit till the gas bits and the insulation get here in a few days. I will need to get the exact height of the insulation plus the fire brik floor before I cut the opening at each end.
  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #2 - Mar 16th, 2017 at 5:40pm
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I had a busy day in the shed with the forge up to as far as I can take it untill the insulation gets here and then I got the bolsters on two of the knives I am doing and the handes on the third.

This is the stage the forge is up to now and if you look closely I cleaned the floor for Gabriel  :wink: :wink:

https://www.youtube.com/watch?v=zDfeiwCa5c0&feature=youtu.be
  
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Kersh
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Re: A gas fired knifemaking forge
Reply #3 - Mar 18th, 2017 at 7:31am
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Very cool. Looking forward to seeing it running  Smiley
  

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Von Gruff
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Re: A gas fired knifemaking forge
Reply #4 - Mar 18th, 2017 at 4:14pm
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Made some progress on the forge yesterday and the first thing I needed to do was to get a hole through for the gas supply. I read some more on the angel of delivery and ended up going with the full 30 degree offset. So lots of 1/8 in holes round the perimeter



Some time with a good 1/2 round file, the insulation in and away down to the garrage to get the the end welded on and the outer gas delivery pipe welded in


The venturi system has a nice air supply regulator with it fully open here for full heat forging. I saw a video with this gas system and he reached welding heat in 2 1/2 minutes


And closed right down. For the heat treating the air supply is closed down quite a bit to controll the temperature





  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #5 - Mar 18th, 2017 at 4:17pm
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The fire brick was placed in and settled down into the insulation



The rigidiser was sprayed onto all the insulation, the refractory cement was mixed and laid into place



Now I have to wait a few days for it all to dry before it gets a firing


In the meantime I had a look at the piece of a press die I got from the scrap yard the other day. It is a ft and a bit long x 4 3/4 x 2 with the bottom very neatly radiused


I decided it is a bit long for what it may turn into so I have marked it out to be cut back to 8 inches and will look for a piece of 4x4x8 steel and a piece of 2 or 3 in round stock when I am down to the city again next week. It is all going to be reconfigured into an anvil for a bit of steel pounding which almost certainly means that some work will be done on it with hot steel and a hammer.


  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #6 - Mar 19th, 2017 at 4:32pm
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I got the three knives I have on the bench all handled over the last couple of days and today saw them all shaped up and sanded through 220grit.

brass and micarta



ebony and zebrawood



This one though is a synthetic material of some sort (from a bench top) so is ready for a coat of sealer but am yet to find out if he wants a sheath for it.
  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #7 - Mar 22nd, 2017 at 5:54pm
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The knives are all finished now so I just have to hot wax the sheaths, give everything a final going over and they will be ready for delivery.






There was another two that needed the finish to the handles so they were attended to as well.



  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #8 - Mar 22nd, 2017 at 5:54pm
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A little more on the preperation for the forge and its accesories after a run into the city yesterday

I remembered a piece of 20mm wearalloy I had as a target plate and looked at it as an anvil top instead of the heavy die plate but will make a final decission later on although I cut and preped the wearalloy just in case I decide to use it.



I got a block of steel for the main body that is 200 x 200 x 100 and a plate for the bottom that is 300 x 150x 20 and they weigh in at 33 kg so if I go for the die plate at 17 kg that will be a 50 kg anvil.



I made an 200 x 150 stump under the end of a heavy stool to sit the anvil on so it should have a steady solid base.


When I was doing a bit of work on the brother in law's carport and widows yesterday, I asked him if he had any old fire extinguishers as he used to work for a fire protection company before he retired and he bought out this beauty and gave it to me. It is stainless steel and will hold 13 liters. I am not sure if I need it full depth but I hate to cut it down.


Two new 9kg gas bottles, a regulator and hoses for the forge have all the bits necessary to finish it now and just have to get the rest support tubes welded on and it can have a painted and be fired up. I will have to make a barbeque type trolly to sit the forge and gas bottles on but have enough inch angle in the shed to do that, and will get to it over the next week or two.
  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #9 - Mar 23rd, 2017 at 5:33pm
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The fire extinguisher  quench tank had its  top cut off and a lid made but there is still a couple of handles to be done for the sides for when it needs to be shifted. With a 3 1/2 gallon capacity it should do nicely.





The steady rest was welded up and so the forge could get a coat of high temp paint.



  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #10 - Mar 23rd, 2017 at 5:42pm
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Needing something to set the forge and gas bottles on, a few bits of angle iron were cut into apropriate lengths with a top and a shelf cut ready for when it is welded up.



Then it was back to the anvil. The base had the mounting holes drilled and the heavy block cleaned up. I decided to go with the die plate and cut a piece off the end that will be welded on the heavy block with a step down. I still have to do the hardy holes and get a horn made.

  
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blackgear nz
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Re: A gas fired knifemaking forge
Reply #11 - Mar 28th, 2017 at 5:59pm
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Very clever, looks excellent!
  

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Von Gruff
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Re: A gas fired knifemaking forge
Reply #12 - yesterday at 7:13pm
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There was progress today with the forge bench done and everything set up so as soon as the new regilator gets here it will be all go.
I took all my anvil parts down to the garrage and had it all welded together. After a bit of time cleaning up all the welds and splaters it was bolted to the stool top which will be bolted to the concrete floor but in all reality it is really quite stable.



  
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Von Gruff
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Re: A gas fired knifemaking forge
Reply #13 - yesterday at 7:16pm
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I did a short video of it all sorted for now.

https://www.youtube.com/watch?v=zNizltSvmQk&feature=youtu.be
  
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