Another (Crazy?) Idea for Engine Kits

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Re: re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Tue Dec 20, 2005 6:43 pm

Dang911 wrote:One question though, could you clarify the position of the fuel/air tube? From what I understand, it needs to be centered in the intake, and the "super complex" tool is for?........ I like the smell of the tool, strawberry maybe?

Do I push the fuel/air tube it in as far as it will let me go before the bend in the tube stops, hitting the engine?

OK, this is a question that shows my instructions aren't clear - so, I'll repeat your question on the Construction thread and clarify there.

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Just One More Little Thing

Postby larry cottrill » Wed Dec 21, 2005 12:45 am

Dang -

As you work on your kit, think about one more thing for your evaluation:

How would it have been if it had been done as a 'tack welded' kit, i.e. only the plug mount, engine mount lugs and air tube mounting rings would have been fully welded, the rest just tack welded for you to finish? More/less challenging, more/less fun, too difficult for beginners, still too easy for "serious" metalworkers, etc. ?

Such a kit would be much easier to produce, much more effort for the builder, but still solves all the potential fabrication and alignment problems (except for the tailpipe and air tube). Think about this as you get to your final evaluation. (Of course, the kit could be offered both ways, at two diferent price points.)

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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 1:40 am

I think that would be fine. From my perspective, I find the hard thing for me to do it find a place to fabricate all of this metal. I have the know how, its just finding the machines to use. Unfortunately, I don't' have a machine shop to work at, as it closed a while back. If you were to provide the basic shape, with a tack weld here or there, or not even for some, it would still be do-able for a beginner in my opinion, as long as they can weld. Even if they can't weld, in my opinion (again) its easier to find a place they will help you weld something, then do fabricate it...

You could go as far as not even tack welding the dome to the front end, the top seam of the front end, and maybe making slots or something for the fuel mounting brackets so those would self align without you welding them. This way it cuts down drastically on your production time.

At the same time, I see a few parts of the kit that could be improved on, I will wait till she is all finished before stating them, and my proposed enhancement. They will go on the other thread.....

I didn't get a chance to weld anything today, but I hopefully will get to it tomorrow.....
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 8:09 pm

Well today I was about to weld everything up when reality set in, this is thin steel. I was planing on using a gasless mig welder with a flux cored spool. I'm now second guessing myself, thinking that even on its lowest duty cycle, it might still be way to much power. The last thing I want to do is put holes in the thing, especially in an area where there is no room for any "less" metal to be there.

It looks like you welded it with a torch? How would you suggest I weld this; Mig Tig or Torch? I probably could get my hands on a Tig, possibly a torch. Do you think I could use the Mig?

Chickening out here on the welding hehe
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re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Wed Dec 21, 2005 8:39 pm

Dang it, Dang!

Actually, I know next to nothing about any kind of electric welding. From a practical standpoint, here's what I suggest you do:

You MUST have some of the antenna mast tubing left, and it is about as cheap as dirt, so why not cut a few small pieces and practice welding them together? That would show you right away what kind of problems you might have. It would be even nicer to have a teacher or someone like that nearby who is experienced with the equipment you're using, and to even let him try it on the practice pieces. It will sometimes surprise you how quickly an experienced hand can make adjustments in technique that will solve a problem that seems insurmountable at first!

That's about all I can suggest. Either Bill or Mike stated that there is a type of foot control on some TIG outfits (I think) that can give you very fine control over the running current, but I don't remember what it was called or if it was commonly available. It sounds like you definitely want the high-frequency startup option, but I get the idea that's fairly standard. Of course, I'm talking about something I really know nothing about, except that my dad could weld ANYTHING with it, including aluminum alloy aircraft fuel tanks and titanium tail cones that were just about paper thin.

Good luck!

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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 8:55 pm

Yes Tig is that versatile....

The problem I have with the antenna mast tubing is its thicker than what the front end assembly is made from. They might have changed stuff. It still was called antenna mast tube, but it was galvanized (unpainted) and a possibly a little thicker than what you said, which is no problem, I'm just concerned about the front end assembly. The antenna tube is 1.25 mm, and the front end assembly seems to be 0.5mm. Mig will do the 1.25mm steel, but I'm scared about the 0.5mm steel, that's super thin.

Were you using a standard oxy acc torch, or a mini?

I will have to try to find a Tig or a torch, I think......
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Re: re: Another (Crazy?) Idea for Engine Kits

Postby hinote » Wed Dec 21, 2005 9:04 pm

Dang911 wrote:Well today I was about to weld everything up when reality set in, this is thin steel. I was planing on using a gasless mig welder with a flux cored spool. I'm now second guessing myself, thinking that even on its lowest duty cycle, it might still be way to much power. The last thing I want to do is put holes in the thing, especially in an area where there is no room for any "less" metal to be there.

It looks like you welded it with a torch? How would you suggest I weld this; Mig Tig or Torch? I probably could get my hands on a Tig, possibly a torch. Do you think I could use the Mig?

Chickening out here on the welding hehe
Here's some (hopefully helpful) observations:

1. Get some metal, and practice making some welds--before you do the real thing. How are you going to know if the heat is right, unless you've tried it on something? Maybe your MIG is OK--give it a trial run!

2. The most common problem with thin-metal welding is burn-through. This is the result of oxygen being where you don't want it to be. I'm currently using Solarflux B, coating the backside of the parts to be welded. It shields the metal with an inert compound. There's other ways to do it, including making up a cheap (duct tape) dam and filling the inside of the assembly with argon.

3. The closer the fit between the parts, the better. Same reason as 2 above.

4. you're going to be welding some dissimilar metal thicknesses, so practice is again the best remedy. Another "crutch" is to use a metal backing on the thinner part to prevent excessive heat buildup. Copper is considered the best material here--but a big chunk of iron or steel is probably OK, if you don't expose it directly to the weld and/or get it too hot.

5. When you weld the parts, make as many small tacks as you can before running a continuous bead. Also, when running the bead, keep the run short, to prevent excessive heat buildup (one inch length, or less); then, rotate the assembly and do some on the other side. Take your time and keep the parts cool. All this is related to warpage control--start now, it gets much worse when you switch to stainless.

6. TIG does the best job--if you can use it, do so.

7. Practice, practice, practice!!

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."
Last edited by hinote on Wed Dec 21, 2005 9:19 pm, edited 2 times in total.
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Re: re: Another (Crazy?) Idea for Engine Kits

Postby hinote » Wed Dec 21, 2005 9:12 pm

Dang911 wrote: It still was called antenna mast tube, but it was galvanized (unpainted)


Whoa, there!!!!

Don't weld galvanized--you'll poison yourself with the fumes! Besides, the weld will be contaminated and not as strong.

Buy yourself some cheap, off-brand white vinegar (clear); I got a gallon for $1.75 at the grocery store. Pour some into a NON-metallic container and soak your galvanized parts for at least a day--2 won't hurt. The galvanizing will be stripped off by the acid.

BTW I do this for all my hardware (I use cheap nuts and bolts for mounts and fuel injector holders). All these are plated either zinc or (even worse!) cadmium, and the vinegar makes thorough work of removing it.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 9:24 pm

I have only used the vinegar thing once, mostly I just grind the area to be welded. The galvanized plating (zinc or magnese) is very thin so it scrapes of with one or two passes with the angle grinder....
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Re: re: Another (Crazy?) Idea for Engine Kits

Postby hinote » Wed Dec 21, 2005 9:28 pm

Dang911 wrote: The galvanized plating (zinc or magnese) is very thin so it scrapes of with one or two passes with the angle grinder....


What about the inside (I think it's plated too)?

Bill H.
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".......some day soon we'll be flying airplanes powered by pulsejets."
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 9:37 pm

Good point, although I end up grinding the inside of the pipe at the spot to be welded also. I agree 100% practice is what I need. The problem is I don't have any 0.5mm steel. Also I do have a problem with burning-through. I am using a flux-cored spool, BUT, make no mistake, there is no comparison of this to regular gas welding. My welds look terrible from slag, and the o2 is definitely taking its tole on my control ability. I'm doing a fair share of burning-through also, I just don't have enough experience with thin steel.

I think I might have to cave in, and get a "professional" to do it.
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 10:01 pm

I know this sounds cheesy but does anyone think it would work.....

I have access to dry ice. Before welding my pipe with a gasless Mig welder, I could throw some chunks of dry ice in the pipe with the hopes that it would fill the tube fill co2, drastically improving my weld. Another thought I have is just barely puncturing a co2 cylinder (100g), and letting that trickle out into the pipe as I weld.....
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Re: re: Another (Crazy?) Idea for Engine Kits

Postby hinote » Wed Dec 21, 2005 10:28 pm

Dang911 wrote:I know this sounds cheesy but does anyone think it would work.....

I have access to dry ice. Before welding my pipe with a gasless Mig welder, I could throw some chunks of dry ice in the pipe with the hopes that it would fill the tube fill co2, drastically improving my weld. Another thought I have is just barely puncturing a co2 cylinder (100g), and letting that trickle out into the pipe as I weld.....


I think the dry ice thing might work. Think of the CO2 as a liquid--it sits in the lowest areas. Now, seal bottom and sides of your assembly as though you wanted it to hold a liquid.

Use a match to determine if the gas is filling the assembly; it should extinguish the flame where the CO2 gas is leaking out.

I doubt if anybody would recommend puncturing a high-pressure cartridge; you're exposing yourself to possible injury--and besides there's no way to control the gas flow. With the dry ice, the sublimation rate is slow enough to feed gas to the assembly for a period of some minutes, if not longer.

Bill H.
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".......some day soon we'll be flying airplanes powered by pulsejets."
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re: Another (Crazy?) Idea for Engine Kits

Postby leo » Wed Dec 21, 2005 10:54 pm

I now that sometimes CO2 is used in MAG welding instead off the Argon/CO2 mixture.
Maybe you can fill a container with the dry ice, and put a pressure/flow regulator on it.
And then get rid of the flux cored wire, and get a new spool of the thinnest solid wire you can put in your welding machine.
I think you can only use pure CO2 in iron welding, not stainless, but I am not sure.
I think your welds will improve then, I weld with flux core before and its difficult to get a good weld, I can compare because of 31 years of experience with different kind of welding techniques, I started welding when I was 14 Years old in school.
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Wed Dec 21, 2005 11:29 pm

Well after playing in the garage a bit, I don't think the Mig I am using can do the job. Just way to much power!!! I tried the dry ice thing, and yea its a pretty cool (no pun intended) trick. The only difference I noticed, was there was less slag on top of the weld, and a little less splatter everywhere.

Here is what I did. I placed some dry ice in the tube right below where I was practicing welding, and then in a container next to the pipe I placed some dry ice. The fog from the dry ice completely covered where I was welding, so the weld was surrounded in a cloud of co2, or at least until I pulled the trigger....

As neat as of a trick that was, it still doesn't help me weld the thin pipe I have. My Mig, on its lowest power setting, is still burning through the pipe. I think I will have to run down to a muffler shop and have them do some Tig for me. Its the holidays and I haven't asked for anything, I think I will now ask for a tig and a bottle of argon to boot...hehe
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