Trident Mk. II Build Log

[DYI]

The only true NPT sparkplugs I know of are those that the Model T (and probably some of its contemporaries) used, which have a 1/2" NPT thread. They're somewhat oversized for small projects though, and tend to fail at around 2500-3000psi based on my testing.

...the flash was almost deafening.

What size of cap are you using with this flash circuit?

[saefroch]

I just put two photoflash capacitors together in parallel. I know it's nothing compared to what you do, but it was pretty darn loud.

[DYI]

Ah, good. I was worried you might be playing with an ignition system that would directly initiate detonation of the mix

[Mr.Tallahassee]

If you want to use a long reach spark plug you can drill the threads and re-tap the hole. 1/4 NPT fits a spark plug hole almost perfectly. That's how I made my Ghetto Compression Tester.

[saefroch]

I ground down the threads on a spark plug and began epoxying it in, but I stopped with it only slightly attached because I'm not sure if I can see to check if it's arcing when I take the tee that it's epoxied into off. I'll take care of that within the next few days when I get a BBQ ignition system.

Ah, good. I was worried you might be playing with an ignition system that would directly initiate detonation of the mix :p

Oh come on, you know I'm not yet capable of that

[saefroch]

Final additions to the piston are curing now, which means I'm adding the impact-resistant head to the piston that will contact the barrel to push the piston pack. The rear seal is only composed of the end of a bolt with copious amounts of teflon tape around the threads, I'm hoping to maintain some amount of serviceability, since the silicone o-ring on the internal piston will probably be toasted after a few high-mix shots.

If the epoxy cures correctly and the parts stay aligned, I should be able to fix the final pinhole leak and test this as a pneumatic tomorrow.

EDIT: Meat thermometer says my toaster oven only goes as low as 156F

[saefroch]

In all its ghetto glory:
It's... mostly finished. Is it possible that the 5W-30 I use is causing something to swell?

[POLAND_SPUD]

Is it possible that the 5W-30 I use is causing something to swell?

maybe
however as '5W-30' referrs to viscosity of it only we need more info

[saefroch]

Is this good enough?

[jackssmirkingrevenge]

Is it possible that the 5W-30 I use is causing something to swell?

Most likely.

Use molybdenum grease.

[saefroch]

Molybdenum grease? Yeah... I'll look around for it, but will the classic plumber's silicone grease also avoid swelling?

[SpudBlaster15]

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[saefroch]

I think I saw some last time I was at a local hardware store. Thanks, I'll be sure to get some.

[Technician1002]

EDIT: Meat thermometer says my toaster oven only goes as low as 156F

Use a light dimmer to run the power way down. The thermostat won't function, but you can really reduce the heat. Put a light bulb in parallel to get a visual indication of power output.

[saefroch]

Or I could just stick it in the oven at "warm" which is usually 120F.

Spark plug epoxy is curing right now. I don't think I got any epoxy on the electrodes, but even if I did, I should be able to sand it off. Tomorrow I'll be cleaning the oil out, greasing, and pressure-testing everything.