Hot End Assembly

[solodude]

Does anyone have any pictures or know of any pictures that would help me assemble the hot-end ...? Specifically about how to wrap the resistors with aluminum foil and then positioning them...? Also how to secure the thermistor with the adhesive? What kind of adhesive should I use specifically?

Pictures help me a lot ... Thanks a million guys!

-SD

[mhackney]

The H-1 Assembly Manual walks you through it. I am working on photos to add to that section and the H-1 Electronics Manual too. Wrapping the resistors is pretty well described in the manual. Insert the thermistor and then squirt a dap of silicone on it. Don't put silicone in first, it can actually act as an insulator, you need the thermistor to contact the aluminum (but not its leads!). The adhesive is also described in the manual - high temp silicone, you get it at auto parts or hardware stores.

cheers,
Michael

[Fiero2M6]

Here's a couple pictures pasted from John Oly's Yahoo Groups photos. They really helped me a lot. I've also included his captions

"Use aluminum foil to take up the gap in the resistors and the housing. You don't want the foil too tight, and also be sure to NOT LET THE FOIL roll over the ends and touch the wires. That will cause a short and burn up the heater board. Make sure the screws are in holding the steel cap on before inserting the thermistor. Use permatex "ultra copper" or a similar high temp non conductive sealant. I use permatex because i know it can take the heat, and if I ever need to replace the thermistor, it's rubbery and i can peel it back out of the hole and off the housing! Note the resistors are wired in parallel, and make sure the leads can't touch any metal and short out."

"Side view showing the thermistor siliconed in and the clamp screwed down on the resistors. Careful not to crack the resistors by using too much foil, and also you don't want to scratch the green enamel coating either."

[mhackney]

Thanks Fiero2M6, I hesitated to post those photos because John solders hide resistor leads. I don't recommend that, they can get hot enough to melt the solder. Use a crimp connector on the leads instead. No sense taking chances!

Otherwise, the photo of the foil wrap is great. As is the thermistor installation. I also (as described in the manual) use a toothpick to spread a thin layer of silicone on the thermistor leads to make an insulating barrier to prevent shorts.

cheers,
Michael

[Fiero2M6]

Crimp connectors and coating the wires with the silicone is a good idea. I'll be doing that next time its rebuilt.

[Leeway]

The J head hot end I use came with some PTFE tube around the wires. It is pretty cheap. Bought some as spares from Mcmaster Carr.



5335K114
HI-Temp Chemical-Resistant PTFE Sleeving .015" ID, for 28 AWG Wire, 10' Length
In stock
Quantity Per Ft.
1-99 Ft. $0.16
100 or more 0.12



http://www.mcmaster.com/#catalog/118/821/=gzlf8x

[solodude]

Thanks guys this was very helpful.

[Racer]

Is the Teflon tube that come with the H1 kit hot end, suppose to go all the way in to the brass nozzle?

[Leeway]

The J head hot end I use came with some PTFE tube around the wires. It is pretty cheap. Bought some as spares from Mcmaster Carr.



5335K114
HI-Temp Chemical-Resistant PTFE Sleeving .015" ID, for 28 AWG Wire, 10' Length
In stock
Quantity Per Ft.
1-99 Ft. $0.16
100 or more 0.12



http://www.mcmaster.com/#catalog/118/821/=gzlf8x

Make sure you check your thermistor wire sizes before ordering. This size fits my Jhead thermistor fine, but is too tight on the blue lollipop one for the MK 138.

[Racer]

Is the Teflon tube that come with the H1 kit hot end, suppose to go all the way in to the brass nozzle?

[michaellatif]

Is the Teflon tube that come with the H1 kit hot end, suppose to go all the way in to the brass nozzle?

Yes, the teflon tube that comes with the kit needs to go into the nozzle until it stops. If it doesn't the ABS/PLA will pool up in the tip and you will have a mess on your hands.

I have the old style nozzle (extruder assembly) that does not capture the teflon tube and once in a while it will push upwards and pool up the ABS in the tip. I would then have to take the extruder tip off and heat the tip with a heat gun (till its extremely hot - do this in a well ventilated area!) and scrape out the goo.

[Leeway]

I don't have that one, but I would guess yes. This is how it keeps from getting blow back.

[Racer]

Is the Teflon tube that come with the H1 kit hot end, suppose to go all the way in to the brass nozzle?

Yes, the teflon tube that comes with the kit needs to go into the nozzle until it stops. If it doesn't the ABS/PLA will pool up in the tip and you will have a mess on your hands.

I have the old style nozzle (extruder assembly) that does not capture the teflon tube and once in a while it will push upwards and pool up the ABS in the tip. I would then have to take the extruder tip off and heat the tip with a heat gun (till its extremely hot - do this in a well ventilated area!) and scrape out the goo.

Thanks for the info very good to know.