i have been trying tungsten carbide as an electrode material, it conducts well and from my testing i have found that even at high voltages, it holds up very well. i

went to the local surplus store that i visit often, and got a nice selection of inserts for cutting tools. these come in a wide veriety of shapes and sizes and can be built into just about any gap design imaginable? here are some of the usable shapes i picked up for testing.

i decieded that i would use the 3/4" round inserts with the indexing hole in the center for a static gap, i found a pvc pipe end cap with a 6-1/4" iner diameter, this just happened to fit nicely under my muffin fan? i wanted to be able to adjust the gap spacing so that i could try it on diferent power levels so i cut a 1/4" slot in the side, 1" above the base curve, 7" long.

since i had a bunch of 1/4-20 brass bolts with flat heads, these were a perfect choice for mounting, fit perfectly in the insert, conduct well, and the head was just inside the outer diameter of the inserts. i opted for crimp lugs for the tapping terminals, these also conduct well, gave a nice heat sinking surface area, and a fine place to tap with the solid copper aligator clips i use for tank conections.

as you can see, i drilled large holes in the base to force the air past the gaps to help quenching the arc. this gap has performed very well so far in my testing, no chiping or flaking of the edges, even with high powers and no air movement for cooling. although at 12kv and 90ma the pvc did tend to get a tad soft, but with the air flow it performed very well and with the avalability of so many shapes and sizes, and since most machine shops throw them in the scrap box after they dull out, these are an inexpensive alternative to pure tungsten giving a more diverse arangement posability?

i am planing on using carbide for my sync. rotary electrodes and for those that use brass now on there electrodes, carbide flats could be brazed onto the arcing surface by any hvac shop if they don't have acsess to a torch. in my book, it's definetly worth a few phone calls to try to locate some inserts to suite your needs.

here's a small static i made for the coil system i built for my neon supplier. it uses 8 carbide rounds srewed onto some fiberglass board i had from an old ac motor drive.

an after note; as can be seen in the pic of the small static gap i made for the small coil, i used four nitride coated inserts (the gold ones), these DO NOT WORK, in firing the coil on these the arc was very wimpy and thin, almost like there was no tank cap in circuit? after asking the pupman list about this i was told by dale hall that nitrides have a high resistance and so might have been only passing inductive capacitance. it was very interesting to see but it is not what we want for a gap, stick with uncoated inserts and a good "true blue" arc will be had.


	carbide static gap i have been trying tungsten carbide as an electrode material, it conducts well and from my testing i have found that even at high voltages, it holds up very well. i went to the local surplus store that i visit often, and got a nice selection of inserts for cutting tools. these come in a wide veriety of shapes and sizes and can be built into just about any gap design imaginable? here are some of the usable shapes i picked up for testing. i decieded that i would use the 3/4" round inserts with the indexing hole in the center for a static gap, i found a pvc pipe end cap with a 6-1/4" iner diameter, this just happened to fit nicely under my muffin fan? i wanted to be able to adjust the gap spacing so that i could try it on diferent power levels so i cut a 1/4" slot in the side, 1" above the base curve, 7" long. since i had a bunch of 1/4-20 brass bolts with flat heads, these were a perfect choice for mounting, fit perfectly in the insert, conduct well, and the head was just inside the outer diameter of the inserts. i opted for crimp lugs for the tapping terminals, these also conduct well, gave a nice heat sinking surface area, and a fine place to tap with the solid copper aligator clips i use for tank conections. as you can see, i drilled large holes in the base to force the air past the gaps to help quenching the arc. this gap has performed very well so far in my testing, no chiping or flaking of the edges, even with high powers and no air movement for cooling. although at 12kv and 90ma the pvc did tend to get a tad soft, but with the air flow it performed very well and with the avalability of so many shapes and sizes, and since most machine shops throw them in the scrap box after they dull out, these are an inexpensive alternative to pure tungsten giving a more diverse arangement posability? i am planing on using carbide for my sync. rotary electrodes and for those that use brass now on there electrodes, carbide flats could be brazed onto the arcing surface by any hvac shop if they don't have acsess to a torch. in my book, it's definetly worth a few phone calls to try to locate some inserts to suite your needs. here's a small static i made for the coil system i built for my neon supplier. it uses 8 carbide rounds srewed onto some fiberglass board i had from an old ac motor drive. an after note; as can be seen in the pic of the small static gap i made for the small coil, i used four nitride coated inserts (the gold ones), these DO NOT WORK, in firing the coil on these the arc was very wimpy and thin, almost like there was no tank cap in circuit? after asking the pupman list about this i was told by dale hall that nitrides have a high resistance and so might have been only passing inductive capacitance. it was very interesting to see but it is not what we want for a gap, stick with uncoated inserts and a good "true blue" arc will be had. of coarse with the advent of my triggered gap testing, static and rotary gaps may well be a thing of the past?