adrian wrote:Probably a couple of reasons that I could suggest. It weighs more once the ceramic cement is added, adding drag to the X-Axis. The cement will also crumble at the slightest bit of maintenance to the hot end. Its difficult to assemble. Even when insulated, is a lot easier to short than a resistor. Its also not hard to find, but not nearly as readily accessible as resistors. It also has absolutely no mass to it, so its pretty much on constantly where as a resistor/block setup has much more thermal mass and so can be more easily run with PID and thus economically. You also needed to keep in mind the length of nichrome used and its impact in terms of current draw etc.
Basically - its 'cheaper' because it has several draw backs that aren't necessarily appreciated initially.
Of course - the above is entirely my own uneducated suppositions, so perhaps entirely misinformation.
Adrian
I think that weight for weight there wasn't a lot in it.
all the rest, completely agree though! there was no thermal mass meaning that the heater is on all the time, when I rebuilt my heater I used a larger wire, so there was a greater mass per length of wire, and longer length, that did help with the thermal mass, but not nearly as good as the aluminium block I have now.
the ceramic was pretty poor, but I think that there were several options for ceramic out there, I was going to rebuild my hot end using exhaust gasket paste the last time it broke, this would have meant that the stuff dried to a hard, but kind of slightly rubbery block, which shouldn't have crumbled better, but I moved to a block and heater cartridge instead.
it's not only a pain in the ass to assemble, but the furniture screw inserts, (that brass bit was actually an insert that they put in to flat pack furniture so that you can use machine screws rather than wood screws to assemble them) anyway, those bits, could only be bought in large quantities, so it was an unnecessary expense for the home builder.
The wire length, I would kind of argue as a good thing, since it meant that you could select any power for the hot end.
but actually getting wire leads attached to the nichrome wire was an art in itself, so there is a high incidence of breakage there.
the resistor method also has drawbacks. but the block solution is a better solution than the nichrome wrapped brass insert method.
Now take out the resistor and add a heater core, (a metal tube stuffed with nichrome heating wire) and you have a much better solution.
