MakerGear V4 Heatbreak (Barrel) Replacement - V4 Hotend

A customer of ours provided this method for replacing the V4 hotend heatbreak on the MakerGear 3D printers. 

Please note: a new nozzle is recommend when installing a new barrel. Here is what MakerGear says:

"Once a new nozzle has been installed onto a barrel, do not install that same nozzle onto a different barrel or leakage may occur. As you install a new nozzle onto a barrel, a small amount of material is removed from the nozzle to create a custom fit. This makes the nozzle incompatible with any other barrel due to the slight variations in tolerances among different barrels."

Note: Always unplug your printer and wear proper safety gear.

Remove old barrel:

1. Disassemble the hot end; remove the fiberglass sleeve, heater and thermistor from the block
2. Rapid heat the aluminum block (propane torch works perfect). Do not heat too long, the idea is heat the block quickly without overheating the barrel
3. Push the old barrel out (light tap may be needed). This needs to be done quickly after heating.
4. Clean the aluminum block of residual plastic and/or of other contamination

Replace new barrel:

1. Place the barrel in the freezer for 20-30 minutes. This causes the barrel to dimensionally contract a small amount.
2. Keep the barrel in the freezer until ready to insert in block (have it easily accessible)
3. Rapid heat the aluminum block (propane torch works perfect)
4. Quickly retrieve the barrel from the freezer and drop it in into the block, it should seat on its own. This needs to be done quickly before the block cools.
5. Set aside and allow the parts to stabilize to room temperature before handling.
6. The barrel should now be in a tension fit… aka should not spin when mounting the nozzle. 
7. Reassemble the hot end as required

MakerGear also has instructions available here.