SpudFiles

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?

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.

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

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.

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.

DYI wrote: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

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

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

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

Is this good enough?

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

Most likely.

Use molybdenum grease.

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

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Cras nec placerat erat. Vivamus dapibus egestas nunc, at eleifend neque. Suspendisse potenti. Sed dictum lacus eu nisl pretium vehicula. Ut faucibus hendrerit nisi. Integer ultricies orci eu ultrices malesuada. Fusce id mauris risus. Suspendisse finibus ligula et nisl rutrum efficitur. Vestibulum posuere erat pellentesque ornare venenatis. Integer commodo fermentum tortor in pharetra. Proin scelerisque consectetur posuere. Vestibulum molestie augue ac nibh feugiat scelerisque. Sed aliquet a nunc in mattis.

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

saefroch wrote: 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.

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.