Forge improvement: A better Venturi-Burner

I built a new burner for my water tank forge. The first one I built had serious airflow problems and with too much gas it tended to blow out its own flame. So the generated heat was limited.

With my new welder, I was able to rebuild the whole cap. This type of burner is called a Venturi Burner. The gas flow from the nozzle pulls the air through a pipe by the sheer velocity of the movement. The air is not accelerated by an electrical fan or something, it is pushed into the pipe by atmospheric pressure. The mixture of air and gas moves fast enough to flow and mix in the pipe but the flame can not go back into the pipe.

These burners actually rely on two principles: the Bernoulli Principle and the Venturi effect.

An increase in velocity of a moving fluid results in simultaneous decrease in its pressure (and visa versa)

Bernoulli Principle

The result is that the velocity of the gas leads to a lower pressure of the gas (this is what the Bernoulli Principle says) and so the surrounding air (and so the oxygen) at atmospheric pressure is ‘entrained’ into the low-pressure gas flow to even out the difference of pressure, this is the Venturi Effect.

Schematic view of a Venturi Burner

I bought some plumbing pipes made of iron and used a wire brush wheel on my angle grinder and a scraping disc to remove the zinc from the surface. Zinc can lead to health issues if heated and the gases are breathed in.

First I just held the cap near the top funnel and lit the burner to find the right distance and the right gap for the air intake. Then I welded the two parts together. The top cap is the former tip of a usual gas burner used on roofs. I just cut int into the right shape.

Yes I know it is not beautiful but a huge improvement that ads a lot of power to my forge and the flame is more stable at higher settings.

Literature and sources:

Welding steel

As I wrote some times ago I like to learn new things, combine the techniques I learned to something new, and expand my skills. One thing on my bucket list was to buy a welding machine and learn to weld. Probably because I saw my dad try his best with his not-so-good arc welding transformer when I was a child and still I am fascinated.

I looked up different machines, not too expensive for just getting my feet wet, with good reviews, and most importantly it should be as flexible as possible when it comes to welding techniques. I ended up having a look at Stahlwerk Schweißgeräte [unpaid advertising]. I was thinking about to get their MIG 200 amps machine as it was able to do Mig/Mag, arc welding and flux-cored welding. Unfortunately, it was not on stock for a long time on their site and on Amazon. I even got a welding automatic helmet and welding gloves for Christmas long before I got the machine itself.

So last week I did it and hit the “buy now” button as a pre-order. I had decided that for my needs 175 amps would be sufficient and bought the machine. The day the parcel service announced the package I kept hitting the reload on the parcel tracking page, nervous like a kid on Christmas Eve. Meanwhile, the tracking page even got a 500 server error message but fortunately, it wasn’t me. They where just launching a new page 🙂

My 14 years old son trying out dads new welder

I tried to weld some beads onto some scrap metal and oh boy times have changed. It was so easy to ignite the electrode and or the flux-cored wire. No way you can compare that to the old transformer I got in my garage, the old welding machine of my dad. In the end, I had the best results with simple arc welding electrodes.

In the above video you see my son trying out my new machine.

Customer review for the Longbow by JAMZT53

Today I received my Beautiful Longbow, courtesy of the Masterful Hands of Andreas @simplyknives.. The German Knife making Prodigy.. The knife is 11” OAL, with a 7” Blade, that is Razor Sharpened and hand sanded and polished to a Mirror finish..The handle is stabilized green Poplar Burl, which is my Favorite Color.. The Knife is the third Beauty, Andreas has made for me.. He does this part time and this Longbow is his 15th Blade, he has ever made…He also completed a Gorgeous Custom made Leather Sheath..
This knife exceeds any and all expectations I had.. It is amazing.. Feels terrific in the hand and I just love it.. Thank you so much, for all your hard work.. Checkout Andreas @simplyknives ..🇩🇪🙏🏻🤝🇺🇸

Joe Topiah @JAMZT53
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***SIMPLY AMAZING*** Today I received my Beautiful Longbow, courtesy of the Masterful Hands of Andreas @simplyknives.. The German Knife making Prodigy.. The knife is 11” OAL, with a 7” Blade, that is Razor Sharpened and hand sanded and polished to a Mirror finish..The handle is stabilized green Poplar Burl, which is my Favorite Color.. The Knife is the third Beauty, Andreas has made for me.. He does this part time and this Longbow is his 15th Blade, he has ever made...He also completed a Gorgeous Custom made Leather Sheath.. This knife exceeds any and all expectations I had.. It is amazing.. Feels terrific in the hand and I just love it.. Thank you so much, for all your hard work.. Checkout Andreas @simplyknives ..🇩🇪🙏🏻🤝🇺🇸

A post shared by Joe Topiah 🇺🇸Ohio🇺🇸 (@jamzt53) on

The story of my second built of Kukri III

Custom made Kukri III knife with leather sheath

Before I sent the first built of my Kukri III custom knife model to my friend @JAMZT53 I showed the knife around. It was admired by many people, friends, and family – so I quickly got another order for that knife in my books.

After I finished the Longbow I tried a different way to organize my work and started to work on multiple knives at the same time. I began making another PB, Tigershark, and Kukri III model at the same time and planned to switch whenever I had the motivation for a specific step of knife making.

Kukri III custom knife photographed from the top with grey background

While doing so life hit me and I found myself in the middle of switching my daytime job. Don’t get me wrong, the step was planned and long overdue but it brought a lot of changes to my life. With a lot more responsibility and freedom of making decisions, sculpting an entire IT department from the ground up and such. It is honestly an awesome job and it was absolutely the right decision.

As a result, I simply did not have the focus on handcrafting and coming back home late, and then go to my workshop and work on a knife. So knife making got a bit off my schedule. I was all the time looking forward to diving back into it though but even on the weekends, I could not find the time and energy for it.

Times have changed, I “arrived” in the new job and I got a lot of very positive feedback from my new boss and I am obviously doing one or two things right there. That put a lot of wind under my wings and additionally then came the Corona lockdown and we are all working from home. That took away all the commuting to and from work. In the end, I am working a lot more on my job from the home office and on the other hand, I am finding back my way into knife making on the weekends or finishing one or two steps in the evening. And also: It got warmer since spring is here – the small radiator just does not warm up the workshop so nicely when it is cold outside 🙂

Kukri III closeup of the etching on the hilt of the blade
Kukri III with a bit different name tag and my makers mark “SK”

So here I am back, with a finished Kukri III on my table, working on the sheath and pushing things forward to deliver the knife, which by the way came out quite good. I am happy with the final result and look forward to seeing the reaction of the one who ordered it.

Different liner material: Felt

I was looking for a different material I can use for liners. I constantly use liners in the handles between the handle scales and the blade on full tang knives and between the guard and the handle on hidden tang knives.

I usually use Micarta I make out of resin and paper and was looking for other ideas and came up with some felt my kids use for handicrafts. So I gave it a try and made some simple tests:

felt as liner material in knife making
First tests with felt as liner material

I brushed a good amount of epoxy resin on the felt and pressed one between two pieces of scrap wood and the other one I just pressed flat and let both experiments rest for 24 hours. This long wait is just because I use a very slow hardening epoxy.

After removing the clamps I cut out the flat piece with scissors. The wood pieces I sanded flat on 3 of 4 sides to simulate the effect when I use them as liners on a knife handle.

I made some stress tests with the wood pieces trying to break them apart but they are solid and well bonded to the surrounding wood. I wasn’t able to break them apart with a realistic amount of force.


There are some advantages to felt. First of all, it is thicker and the layers needed to reach a certain thickness is clearly lower, this might save some time. Second, the darkening effect when the material is soaked in resin is not as extreme as when using paper so I can better predict the resulting color.

As a disadvantage I have to check if there are air bubbles left in the material. You can see the effect of air bubbles in the flat piece in the picture above – the brighter part in the middle results from tiny air bubbles.

The top picture shows how I fit a Kukri III that I am working on while dry fitting the pieces of felt between the different parts of the handle. Pictures of the finished built Kukri III will follow.

A new and bigger Bowie, the Longbow

The Bowies I made till now were with wide recurved blade design. I like the form a lot but I saw a lot of knifemakers doing a very slim design for their Bowie blades. I also wanted to make a bigger knife to see how far I can go. The main challenge is not grinding a bigger blade into shape but the size of my forge and the containment of the heat treatment oil.

While I planned the new knife, my friend Joe asked me to make another knife for him. This time I should do it completely free as I like and put as much into the knife as I want. When working with and for Joe he always gives me complete creative freedom, but this time I also suggested the knife model. That was perfect timing.

I showed him the draft and he liked it. So I started with the project and got the shape into the steel. I was totally amazed when I held the rough blade in my hand for the first time. The ergonomy of the handle was on point. I don’t know if I have a good sense of handles or it is pure luck. But I like how I can grip the handle with the full fist or put the thumb on the back on the spine of the blade and up to the thumb stop.

I showed Joe pictures of the progress and I felt how he began to love the blade after he just liked it at first. He told me he would love to have a green handle. I had seen nice colored wood at a german online dealer for knife makers. And I showed him the exact piece of stabilized green poplar burl. That stuff looks like jade marble. He liked it and so I ordered it.

The piece of wood looked even better when you see it live – but it made me very nervous to cut the wood into halves. The knife would have a full tang so I needed two parts. I have had some problems getting perfect straight cuts on my bandsaw before. I practiced with some pieces of wood – and it went much better than expected. So I cut the stabilized wood in half and sanded it perfectly flat on a piece of sandpaper that lay flat on my workbench.

The wood left neon green wood dust everywhere – even more, when I started shaping the handle. My workshop looked like an alien landing zone with all the green stuff around. Good, I got my respirator.

As always I left the handle a bit thicker. A big knife like the Longbow needs a handle you can grip on.

The blade is polished to a mirror finish – and I don’t know why but this went pretty good this time. Usually, I have a tough time getting all the scratches out of the wood but this went pretty easy this time.

Trying a different approach to organizing my work

Until now I worked on one knife at a time but I always strive to find the best way for me to work on my projects. Working on one knife at a time meant, for example, to fire up the forge to heat treat just a single knife, it would be much more efficient to harden more knives at a time. Or to carve out the blanks for multiple knives at a time instead of just one and then have to switch tools and so on.

On the other hand, I want to keep the passion I put in every single project – Concentrating on the details that make every single knife unique. To make sure I do not loose this I will allow myself to jump between the projects and push on the parts of the single projects that I am most motivated in.

Currently, I have 4 knife projects in parallel active. I am working on the “Longbow” Bowie knife, another Kukri III, a new Tigershark hunting knife and the PB skinner but with a thicker blade. I started all blades at the same time but now the Longbow is finished for etching and I have a beautiful piece of stabilized wood for it here. All other blades are heat treated and ready to be cleaned up. Only the skinner is already partly ground clean from the filthy remains of the hardening oil.

Customer review for the Kukri III by JAMZT53

From Germany,🇩🇪 with Love..
Big Mail Call day.. I also received this Beautiful Custom made Kukri III, from my good friend and Maker, Andreas @simplyknives.. This Kukri is Flawless and Absolutely Beautiful.. Andreas is one of the most Meticulous Makers, I’ve Ever come across.. His attention to detail on this Kukri, as well as my jamzt53 Knife, is unbelievable..
What REALLY BLOWS me away, this Kukri is his 10th Knife, he has EVER MADE..
Yes, I said 10th..
Knife making is his True Labor of Love and I can’t say enough, just how happy I am, with this Gorgeous Kukri.. Thank You my friend, Thank You..🇩🇪🗡⚔️🔪🤙🏼🙏🏻🇺🇸

Joe Topiah @JAMZT53