Heating coil resistance

[sunkingrecords]

Hi!

I tried the search and also google but came up with no relevant information. How much resistance should measure in the heating coil?
I currently testing a Adamant sapphire, and it reads 0 ohms (that's zero). That can't be right.

Obviously I can't get it to heat because if there's no resistance there is no dissipation of power...

The sapphire was brand new, so the only explanaiton is it came broken (is it usual?), or the resistance is below the measuring capabilities of my tester (which can read as low as 1 ohm) or I somehow managed to break it within two minutes of use...

Kind regards

Miguel

[rsimms3]

Try searching "stylus heating". I know it's been discussed how to measure the resistance to attain proper heating, but couldn't find it with a quick search.

Alan Graves recipe for stylus heating to add it to a Presto -

Alan_Graves_Hot_Stylus.pdf

[sunkingrecords]

Hi!

The thing is, this stylus comes wih the heating wire from the factory. Its a Adamant NSH-2S saphire. I think they should put a datasheet with this information, but no luck finding it!

Everyone mentions 7 and a half turns of Nicrome wire, but who knows what gauge?

[opcode66]

The gauge doesn't particularly matter. You could use a number of different gauges. And, various numbers of turns. There isn't a particular concrete standard. People who make diamonds sometimes have different configurations from Apollo. Additionally, if you look at old spec sheets from lets say Capps or other stylus manufacturers in the past, you'll find variation and deviance form what Apollo sells.

The power supply for the stylus heater should be a constant voltage, variable current power supply with a potentiometer for controlling current and an Ommeter for measuring the current. Typically 0.4 or 0.5 amps is the standard. Use a 1 or 2 Amp DC ohmmeter. I have schematics for those interested in building a proper heating wire supply cheaply with parts easily ordered or purchased locally.

You adjust the potentiometer and monitor while cutting. When you hear your background noise decrease significantly stop. Too much heat is not good. Don't overdo it.

[sunkingrecords]

I may be interested in building a different heating wire power supply, at some point. The one in the Angulo machine does work anyway, but I'm having some trouble dialing a precise and low temperature, with the Transco ruby. With the Adamant sapphire there's no way, because it appears to be shorted.

Kind regards!