Proper PTFE tube replacement/Thermal Barrier Installation procedures for a CTC/Makerbot Clone MK8?

[Al K]

Hello,

I am trying to determine the proper replacement procedure for the PTFE tubing in my thermal barrier for my CTC Dual/Makerbot Dual Clone.  From the factory it comes with a thermal barrier that is just threaded on the bottom such as the one shown here:

Im looking to find out how long the PTFE should be?   Like should it be the same length as the tube?  Should it extend into the nozzle?  Should it extend past the top of the tube?

Also I wanted to check on the proper procedure for threading the tube and nozzle.  I understand you do not want the nozzle to thread against the heater block, right?  So is the best way to thread the nozzle first all the way in and then back it out 1 turn, then thread the tube in all the way down and then tighten the nozzle against the tube? 

Last question is about thermal paste...  where is the recommended spots?  On Nozzle threads?  On Tube Threads?  PTFE?  Nowhere?

Thanks in advance guys...  I'm a bit new and I have been reading alot of info, but I see many different views posted and nothing much specific for this tube that only has bottom threads.

[Jetguy]

You have what would be a MK9 Flash Forge extruder. These are NOT very common and no longer in production to my knowledge.

This is different than the Wanhao MK9 (just for reference).

This style uses a 3mm outer by 2mm inner PTFE tube that is rarer.

The length extends BOTH into the nozzle and to the top of the tube.

I do not have the length- these are rare like I said.

DO NOT put any heatsink grease on the threads to the heater block. It's not a good idea and worse, would degrade from the heat and gall the threads.

The only place that you would put heatsink grease is on the smooth upper part that slides into the cooling block, and is held by the setscrew

Yes, your nozzle procedure is correct. Turn the nozzle until it bottoms. Then back off 1/2- 1 turn. Thread in the thermal barrier with liner. Hold the thermal barrier tube and tighten the nozzle.

What I do is put a 1/4 hardened bar through the heater core hole, hold the block with one hand using the bar to prevent rotation, hold the thermal barrier tube normally by finger and then use a 6 point socket for torque on the nozzle.

Obviously don't snap the nozzle off,  but you can feel it seal and tighten against the thermal barrier.

Again, then install into the cooling block with a light bit of thermal grease on the upper portion as it slides into the cooling block.

[Al K]

Jetguy, Thanks so much for the breakdown - I understand.

Also, thanks for identifying the extruder, as I have had trouble finding any information on it.   If you don't mind me asking are their any extruder upgrades you recommend for the model other then full replacement?

Thanks again!

[Jetguy]

There honestly isn't much in the way of upgrades other than a new nozzle.

Here is the correct OEM style in brass http://www.makergeeks.com/du3dprremk7o.html

Here is an example upgrade nozzle with a coating that makes it stay cleaner http://www.p3-d.com/products/mk9-teflon-tube-compatible-extruder-nozzles
And, they sell the correct tubing here (I would buy it by the foot and cut to length) 3mm OD and 2mm ID http://www.p3-d.com/collections/replacements-parts/products/teflon-tube

make yourself a cutter
http://www.thingiverse.com/thing:418777