[28 Feb 2022]

CHC Pro and heatbreak for the SecSavr Slight [gd0089] 

The SecondSavr Slight is the name of the custom extruder that I'm designing instead of the originally planned metal BMG from TwoTrees, as £19 incl tax per extruder is a lot. Along with 2 spares, I'm planning the stock gd0036 setup to consist of 2 * (2 0.8mm nozzles + 2 0.2mm nozzles) (4 nozzles per SecSavr Slime [gd0088]). This means that, with 2 printer "cores"/"bays", 18 extruders are needed. The only reason I needed the metal BMG's was for the integrated heatsink, but on searching for something else, I found £3 "High Flow" bimetal heatbreaks with integrated copper cooling fins. 

Now for some reason, I've never really liked the idea of using these £19 BMGs, and after the 5th time searching to see if any hip new extruder hit the AliExpress market, I remembered back to those heatbreaks and thought about just designing a custom extruder. I had also just recently seen this extruder, which reminded me of this extruder I saw way back in maybe 2017 - I considered it the fanciest looking hotend but the price was (and still would be) too much. Ever since then, I've always wanted a double drive extruder, and now was the opportunity to get it. 

The design of the heatbreak allows me to go straight from the extruder gear into the stainless steel tube, which should be an even more constrained path than a metal BMG and normal bimetal heatbreak as there is a larger hole that is chamfered to the steel tube.

It also seemed that, if I took off the blue silicone seen in the product listing, I'd also be able to replace the bolt holding the metal wire strain relief with a titanium bolt to possibly have a single handed nozzle change -- a feature seen in todays latest hotends.

Due to the aluminium spacers as a melt zone extender (idea from the Rapido hotend), and the desire to print up to the maximum 300C allowed by the CHC Pro's stock thermistor, I'm using good old fashioned ceramic wool + kapton tape to insulate the hotend instead of the nice looking included silicone sock (which is an upgrade to the E3D-SuperVolcano-like insulation its predecessor included). 

If you're not aware, the new CHC Pro is a 60 - 115W ceramic heater around a plated copper block. It consumes more watts when cooler to speed up heating times. It feels like the included power wire is a silicone wire instead of the typical fiber sleeved wires on heater cartridges.

Anyway, to my suprise, the blue silicone sleeve surrounding the high flow heat break aiirved in white, and it's rigid. It's not silicone at all. 

I'm going to need to ask the seller if it's able to handle 300C, and figure out how to take it off if the answer is no. Conveniently, the screw hole is still accessible even if it's left on:

I've gone with the High Flow variant as the regular version is the same height, the high flow has a higher heat sink that will be encompassed by gd0089 and high flow = more flow, presumably. 

Here's all the components together, with the metal BMG  for scale:

Truly compact stuff.

Airbrush nozzles

I know they were going to be small from the product listing image, but the airbrush part is truly tiny. The thread for it is very small too. I wonder if it's possible to actually get any volcano hotend with a sufficiently large orifice and tap out the thread.

 I just hope that the black sealing ring is something like silicone or another material that can safely handle printing temps. Anyhow, these nozzles are intended to be used with this volcano block adapter as the proper nozzles from Mellow cost way more. I just got 5 of each for testing purposes. 

I usually use 0.6mm nozzles, and any time I want to print in 0.4, I usually want something of even finer detail. There's almost no online experiences with airbrush nozzles, so I never got around to getting one to try until now. Ideally, I'd like UV resin prints without the UV resin drawbacks of single colour printing and, more importantly, the cleanup and health concerns (gd0036 is likely going to be over my bed). 200 microns might not be as crisp as the Form2's 140 micron minimum dot size, but I should be able to get some crisp-for-FDM prints.

Tubes

So on the 26th, I received a new set of ordered 400mm tubes because the first set was out of tolerance. The quality sure increased. They're shinier.