this one looks like it could be in the top 5 for crazy looking. I didn't want to hard wire in the battery charger until I saw how it worked, so all temporary connections. First nichrome wire lasted 5 minutes, second one finished the vessel. So not too steep of learning curve on basics, but I've got a ways to go on tip control. With 1 1/2" flames shooting off the work, it takes a technique to make the placement. I was really pleased with the vessel, then I took a picture. My camera is better than my eyes, so surprised to see the gap distance between the burns so far apart in the top border I made. I'll wait till a latter burn to show the results.
Re: I've made some Rube Goldberg looking devices, but
And I don't have much control over the tip either. I need more practice. If you ever get to watch Graham Priddle use his "wood Vaporizer" 1 1/2" flames are normal.
Re: I've made some Rube Goldberg looking devices, but
Can you turn it down. I know you want to brand but does it really need to be that hot. I brand with my optima burner without flames. It takes about 2 to 3 seconds per burn which does take patience. I bought one of the battery chargers with the intention of making a wood vaporizer but that was just before my move and it's still sitting on some shelf somewhere. guess I'll have to dig it up.
Re: I've made some Rube Goldberg looking devices, but
The thing that makes the temperature hard to control is that the output voltage of the transformer in the charger is way too high. (12V or more) This, together with the characteristics of the dimmer, makes it rather difficult to reduce the temperature to a reasonable, useful level.
Here's why: You have to turn the dimmer "way up" to get it to start conducting. But the turn-on setting is so high that it will then overheat the tip. If you try to turn it down, the dimmer will stop conducting before the tip temperature is reduced significantly. It's a little bit like all or nothing.
Older chargers used transformers with both a 6V and a 12V output. If you set the charger for 6V (for a 6V battery), the dimmer would then work well enough to be usable. Newer chargers regulate the charging voltage electronically, but unfortunately, the dimmer screws up the regulator.
So, unless you want a flamethrower, the whole idea of using a dimmer in line with a late-model battery charger is not likely to work.
An alternative approach is to forget the charger and use a transformer that puts out 6V at about 10 A. Such transformers were commonly used as filament transformers in vacuum tube electronics but are now hard to find and are quite expensive even if you can find one. Note: Ten Amps. A smaller transformer will simply burn out.
Another way is to use a variable transformer in front of a 12V transformer from a late-model battery charger, and this method works well. However, the cost of the variable transformer (Variac) is $100 or more, typically, and you need some electrical skills to put it all together.
My suggestion: Buy a store-bought burner that will do the job if you are serious about it. Someone else can suggest the make and model.
Sorry to bear bad news, but that's just the way it is.
~Doc
Re: I've made some Rube Goldberg looking devices, but
I was running it down around 7 amps on the charger, out of 15 max. At 15 the wire would instantly burn through, probably even at 9 it wouldn't last long. One reason the flames are so high is because of the area of the wire in contact with the wood. There is a lot of gas released from that much contact area, so it ignites from the red hot wire. I have over an hour on this piece of nichrome. The contact with the wood is just an instant. As fast as you touch it you, you get right back off. It's just a touch and go, that's the whole reason for building it. Well that and the depth of texture you can get. I did that demo outside because of all the embers that are floating around. It's definitely a technique that needs safety considerations for your shop!
Re: I've made some Rube Goldberg looking devices, but
Mine regulates just fine. Maybe not at the micro level my Burnmaster does, but like I explained this is at the level I want to burn at. There's no bad news, it performs exactly like I want it to. It's not supposed to be a detail and shading tool.
Re: I've made some Rube Goldberg looking devices, but
Graham Priddle mentions the same thing about some of the newer chargers, but if you just pick up an older one at a garage sale, you really have decent control over the tip. It's not meant to "draw with", but you'll never get the amperage and heat recovery out of a "professional unit" that you will out of the battery charger.
I have a friend who worked on the original radar system that made one out of a DC supply. It works more like a "professional unit". You can get subtle texture with it, but my wood vaporizer can go much deeper.
Steve
Re: I've made some Rube Goldberg looking devices, but
Yes, several for testing purposes and for other people. I've built all three types I mentioned with the objective being fine control of the tip temperature for use in "branding."
One rig I played with would send 30 A through a coat hanger wire. That was a hoss but I thought not good for anything that you couldn't do with a blowtorch.
Bottom line, of course, is that if it does what you want it to do . . .
~Doc
Re: I've made some Rube Goldberg looking devices, but
A few of my local wood turning club members have gone with converted battery chargers.
I decided it was easier to purchase a benchtop power supply. I thought this would be useful for other purposes in addition to wood burning. A link below to the one I purchased in case anyone interested.
The short length of nichrome in the burning tip does not require much voltage. The benchtop power supply only supplies the voltage required.
Turning up the amps controls the burning tool temperature.
" It's not meant to "draw with", but you'll never get the amperage and heat recovery out of a "professional unit" that you will out of the battery charger."
I built a "Graham Priddle" one with a cheap basic (non electronic) Sears charger for about $45 and it "draws" just fine. The fine hair on this maple plate was easy to burn with a knife edge nichrome tip. Or I can turn up the Dimmer knob and burn with it.
Re: I've made some Rube Goldberg looking devices, but
