I'm going to junction today to buy the hot end parts (I'll be getting several bolts and acorn nuts, and enough washers & jam nuts to make two hot ends)
Fastenal 243-5754, pn 75170: brass ¼20 acorn, ea. ¼20 no more than an inch. 5/16 3" 10 in the ¼20 4", $17.90, 5/15 3" $40.25 for 25 of them.
Peachtree hardware on north has the acorn nuts but not the stainless steel bolt. 970-245-1736
Classic computer in delta has heatsink compound, little syringe full for 8.95. I'd prefer something cheaper (in both senses of the word) but that's available today, so I'm going to go for it.
I found a tool that would work for putting a taper on the inside of the extruder. It's 1/4" per foot taper, called a "taper pin reamer" designed for making tapered holes for a tapered pin.
More info on taper pin reamers:
http://www.icscuttingtools.com/Reamers.htm has a pdf which lists gauge sizes, with tip and end sizes in decimal inch for each end of each reamer. According to that I want a '5/16" (2/0)' size, which has a tip of .1137 (<.125) and a large end size of 0.1638. It's flute length is only 1-9/16", but the overall length is 1" longer, so I should be able to get it deep enough in the barrel to taper the melt zone!
http://www.toolsavings.com/default.aspx?page=item+detail&itemcode=2191020 Found a 2/0 for 7.25+shipping which was the best price I found. But their order page didn't load after giving them my CC#. I guess I'll have to wait till Monday to see if they received my order... The taper isn't essential to extruder operation, but would help especially with some types of plastic. (PLA?)
Things I got done:
Peachtree TrueValue lied to me, they had a few of the smaller sized acorn nuts that where solid brass, but the rest are brass plated. So I got the two that looked most likely to be solid brass and called it good. I got enough jam nuts (half nuts) and big fender washers to make two extruder hot ends.
I went ahead and got 25 Stainless carriage bolts, for ~$44. Way more than I need, but maybe I'll sell a few? I can hope.
Fairly major accomplishment, I got the end-stops rewired using 18/2 shielded, it's white tempurature control cable I had left over from working on St. Mary's in junction. The grounds now go to the breadboard, and the ground topology should be more favorable to noise suppression now.
Next up on the Todo list:
re-secure X and Y axis guides to eliminate twisting of the bed.
Test endstops, and endstop code. See if debounce is adequate.
Drill a couple bolts for the extruder.