switching from resistor to heater cartridge

Hey guys I know very little about this and have not found any solid info yet but I'm switching out the resistor that j head uses and trying one of the 12v 40w ceramic heaters.

I'm not sure if my original extruding problem was related to my resistor but if not it couldnt be helping the issue i can't ever seem to crimp the connectors properly on the resistors and soldering seems to not last due to heat range so I figured out the ceramic heater would make things a lot easier with wiring up.

Will there be anything I have to change in the firmware or hardware with this ? I'm using ramps 1.4 and power supply from old HP computer

Sometimes you need to limit the current to the heater in the firmware or at least I had to as the cartridges heats up REALLY FAST. I'm not sure about anything else but if you're looking for a heater cartridge I have some on ebay for a great price. Hope that helps!

Already purchased the heater cartridge thanks though. I just need to know how I would go about limiting it

Hi guys, I'm looking for a cartridge that fits the J-head, since the one I got now it too long! Where can I get a shorter heater cartridge?

How long is the one you have Ohmarinus?

Ohmarinus Wrote:
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> Hi guys, I'm looking for a cartridge that fits the
> J-head, since the one I got now it too long! Where
> can I get a shorter heater cartridge?


Where did you get yours ? I didn't think about that I will let you know when mine shows up if it fits cause I have a j head as well

Tatoo you should find a setting similar to this in your configuration.h:

Quote

#define PID_MAX 175 // limits current to nozzle while PID is active (see PID_FUNCTIONAL_RANGE below); 256=full current

Oh OK thanks

Also while I'm thinking about it, the J-heads have a heater block that is about 16mm long (across the hole for the cartridge). All the heater cartridges I have seen are about 20mm. This is normal and will not cause any problems.

I have also heard that the hole can be bigger than the cartridge and to fix this just wrap aluminum foil around the heater for a snug fit

I have yet to see that one yet that wasnt 6mm but thats a good idea...

I have done this on my printer, no need to edit firmware, maybe power settings and max temp setting in the printer console, thats about it

Crussell Wrote:
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> I have yet to see that one yet that wasnt 6mm but
> thats a good idea...

i have had entire batches which were oval in shape or weak wiring or simply just DOA,

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Sounds like some poor quality control going on

tattooedfish Wrote:
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> Sounds like some poor quality control going on

yep part of the reason i'm not reselling heater cartridges, same goes with 12v 40mm fans, the soldering job on some of them is terrible

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I’ve been back and forth about this. Resistors i can get 25 for cheap and have them in 3 days. cartridges are a lot harder to get a hold of, but once you have them i can understand why you would use them, heat up time can be under 2 minutes, and as long as pwm limited, they should last . My issue was I have had one where the lead wore off.

I like how easy the resistor is to change out, especially if you don’t use crimps, but tinned alligator clips

I'm a newbie to all of this rep raping but for the life of me I cant seem to find anywhere which stocks the crimp tools and ferrules small enough to hold the resistors/thermistor. Tried maplin and they were about as much use as a chocolate fire guard and rs is like looking in a library unless you type the right things you get a load of rubbish. Or the small molex connectors any help would be greatly appreciated If anyone knows.

look in the electrical section of a hardware store. if worst case look in automotive section and remove the outside plastic from those crimps. but if you want easy to replace if it dies then this alligator clip works great. found at radio-shack, and in walmart automotive section.



also it is a good idea to insulate around the resistor leads. otherwise the lead may oxidize all the way through!

Edited 3 time(s). Last edit at 08/10/2013 03:46PM by jamesdanielv.

So did you receive yours yet and how long is it?

I am opting to buy a 20mm long one now, because the one I currently have is 23mm and it s*cks with a J-head.

Ohmarinus Wrote:
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> So did you receive yours yet and how long is it?
>
>
> I am opting to buy a 20mm long one now, because
> the one I currently have is 23mm and it s*cks with
> a J-head.


I "think" it showed up today I won't know till I get home but will report what I got

Alright, I've discovered there are only 20mm and 23mm versions, so it's 50/50

I am going to order a pack of 10 through Ebay!

This one is 20mm long and I had to drill out the hole in the j head to get it to fit but not by much

tattooedfish Wrote:
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> This one is 20mm long and I had to drill out the
> hole in the j head to get it to fit but not by
> much


I had to drill too a bit for my J-head, okay congrats, I bought a pack of 5 or 10 yesterday, curious how it turns out

So far so good i did a print last night and I think its the best print yet

I would recommend using a 3.6Ohm wirewound resistor instead of a 40W heater cartridge. I have tested several heater cartridges from different Chinese suppliers and they were all poorly manufactured in one way or another Plain resistor heaters are cheaper and you don't have to worry about poor tolerances.

Eric

RP Iron Man Wrote:
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> I would recommend using a 3.6Ohm wirewound
> resistor instead of a 40W heater cartridge. I have
> tested several heater cartridges from different
> Chinese suppliers and they were all poorly
> manufactured in one way or another Plain
> resistor heaters are cheaper and you don't have to
> worry about poor tolerances.
>
> Eric


Not sure which ones u tested or what u would define as poor quality? But so far I'm getting great results out of mine and also by the time you factor in the wiring heat shrink connectors and resistor depending on who you buy from you come out spending more on that then the heater cartridge. Out cheaper in my opinion.

I

Why cant we use the heater block as the resistor and just short the connections so it heats the block up as the actual resistor

The block will have too low of a resistance.

Well, my heater cartridges probably won't arrive until late next week so maybe I'll just skip ahead and start printing with the wirewound-resistor for now...

nechaus Wrote:
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> Why cant we use the heater block as the resistor
> and just short the connections so it heats the
> block up as the actual resistor

Now that is a neat idea, as mentioned the resistance would normally be too low. Still have to mount the thermistor and make sure it is electrically isolated as before.

Also most decent thermal conductors are also decent electrical conductors. That is not to say there is no way of working around the problem.

There might be some way to cut a labyrinth in the heater block part so the resistance to the current goes up but this would also generate the heat at a distance from the melt zone and it will not conduct that well unless there is some clever electrically insulating thermal conductor to flow the heat to where it is needed.

Alternately by using higher currents with thicker wires can be an answer, a control that switches the input of an intermediate low voltage transformer (say 24Vac to 1Vac) (or direct opto isolated mains switching for those comfortable with it) then using the stainless steel part of the nozzle itself to be the heating portion, sort of like a spot welding transformer. Perhaps have the current pass from one side of the nozzle to the other where the walls are thin at the melting zone and connecting the wires to wings that are machined from the solid part so no connection problem or clamp the contacts onto the two sides somehow.

I like it a lot from the engineering simplicity point of view but the currents required for the heater cables to make this work in practice would favour a system with a X-Y bed and just a slowly moving Z for the extruder.

KalleP
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Johannesburg, South Africa