Poorly Designed Hotend on Pro2

[Hellsbellsidaho]

I have had my Pro2 for two weeks and it has worked great up to a few days ago and I got a clogged right extruder. I had to remove the right hot end to clear the clog and that's when I realized how poorly it was designed. Very little thought was put into the design of the hot end. I am an engineer and if I had design it I would quit my job and become a greeter at Walmart.

[Jetguy]

How about some pictures of what details you found?

That's kind of the problem, those of us who would take pictures and explain it, aren't buying this printer.

[jon_bondy]

I, too, would appreciate a more specific explanation about what you found and how you would change the design.

[newraiseuser]

On the Pro2, can you change to the Bontech extruder?

[Jetguy]

On the Pro2, can you change to the Bontech extruder?

It is already a Bondtech extruder, but really, that's just a feeder.

The key here is terminology.
Technically, an extruder is a system of components working together.
You have the motor and feeder assembly that grips the filament and pushes it into the extruder.
Then you have the hotend assembly that really is also multiple components of the throat tube (AKA thermal barrier tube), heatsink, heater block, heater cartridge or rod, thermocouple temp sensor, and last the nozzle. As an additional part, there is the required cooling fan to blow air through the heatsink.

What appears to be being complained about on the Pro2 is the actual hotend system- that now includes how the entire hotend can move up and down in it's mounting. Since Raise 3D has nothing other than the stock photos in the advertising of the system, we need fellow owners of the new Pro2 series to post good detailed photos of the construction and assembly.

What we would like to better understand is how the mounting has changed to allow up and down movement, but not side to side, and also any changes from the stock V2 normal non-pro, non moving hotend.

V2-Hot-End-Assembly-6_600x600.jpg (8.6 KiB) Viewed 570 times

[Hellsbellsidaho]

How about some pictures of what details you found?

That's kind of the problem, those of us who would take pictures and explain it, aren't buying this printer.

The attached shows the issue. With no mechanical stop between the heatsink and heater block the nozzle can potentially be off by thousands of inches. Raise3D uses threadlocker but when I removed the hot end the threadlocker did not hold and with the lack of the mechanical stop it is guessing game where they should be located.

[Jetguy]

The nozzle must mate and seal to the thermal barrier inside the heater block. There never will be a mechanical stop where you are pointing.
I'm all for a healthy discussion, but again, your diagram, that's not the issue. What detail I cannot tell, is if the heatsink is rigidly attached to the thermal barrier tube, or if that is in fact the sliding joint. If that is a sliding joint, then again, the DOWN position of the nozzle will be set when the shoulder of the moving tube and entire hotend bottoms out against the top of the block. The up position does not require any set position.

[Jetguy]

Again, what we need is more details of the system- where this is mounting to, what is sliding, to better understand and make an assessment. I'm sorry, but your first reply, Please, review the V2 nozzle assembly guide, where you are expecting a stop is not correct. https://www.raise3d.com/pages/instructi ... assembling
I understand that guide is for a different system but again, the fundamental concept is, the throat tube or thermal barrier is a known fixed size. The nozzle is in theory, precision machined to a standard in length from tip to threaded shank entrance. When those 2 mate inside the heater block, this forms distance "true A" in my edited diagram. Again, dimension A as you have diagrammed doesn't matter a hill of beans. That is not a fixed relationship and could vary between assemblies.

[Jetguy]

Again, After seeing your picture and reviewing it, the million dollar question is more about the socket and or mounting system that hotend is mating to. The older V2 system used the squared off boss of the head of the throat tube to give an adjustment point. This newer system has a much smaller and round shaped boss at the top of the tube. The heatsink is loads smaller than a V2 heatsink. This reduced area, the smaller potential mounting contact area- these are the details that make or break this hotend system IMO. And that's the problem, it's the parts we still don't see.

V2-Hot-End-Assembly-6_600x600.jpg (8.6 KiB) Viewed 506 times

VS

[Hellsbellsidaho]

I measured what you noted as True A as 1.333". I then turned the heatsink 90 degrees remeasured and it was at 1.341". My dimension A also changes of course. The top of the heatsink stops up against the collar shown in my attached photo. So if dimension A changes then it will not be at the correction height to the other extruder and the bed.

[Jetguy]

I can see right now, trying to explain indexing this to you is not working. I don't know if you read the V2 hotend assembly guide, if you understand that the heatsink is not the end all be all locating point is, this or what, but again, highly recommend you understand how the hotend is properly assembled and sealed since you have taken yours apart- you are likely to get a leak.

Thanks for the pictures, I now have a solid understanding of what we are dealing with. There is a moving hollow shank, hopefully in some type of bearing assembly, then a clamping coupler that holds the hotend assembly to the moving shank. Hint- that is the area where nozzle adjustment of height would be accomplished.

[Hellsbellsidaho]

I can see right now, trying to explain indexing this to you is not working. I don't know if you read the V2 hotend assembly guide, if you understand that the heatsink is not the end all be all locating point is, this or what, but again, highly recommend you understand how the hotend is properly assembled and sealed since you have taken yours apart- you are likely to get a leak.

Thanks for the pictures, I now have a solid understanding of what we are dealing with. There is a moving hollow shank, hopefully in some type of bearing assembly, then a clamping coupler that holds the hotend assembly to the moving shank. Hint- that is the area where nozzle adjustment of height would be accomplished.

You must not have a Pro2 because the assembly guide you linked is not the same used on the Pro2. The top of the heatsink stops at the plastic coupler shown in the photo I provided. Therefore if dimension A is off by a twist of the heatsink then the nozzle is off also.

[Jetguy]

I'm honestly trying to help you with a lack of specific Pro2 manuals.
I know full well yes, I do not own a Pro2.
I also know, the pro2 heater block, nozzle, and throat tube/thermal barrier tube works the same basic way.
And the instructions I linked cover that part of the assembly and specifically sealing of the nozzle.

Again, listen to me, this is for your own good.
The rotation of the heater block is the LAST thing to worry about. What matters is, you screw the nozzle into the heater block from the bottom. The throat screws into the heater block from the top. Inside the heater block, the nozzle and thermal barrier are held against each other by screwing them both in at the same time. Since the thermal barrier tube is thin wall, it is imperative to NEVER apply torque across it. As such, you really tighten the nozzle into the heater block unit it presses against and seals internally, thus causing friction in the threads so nothing spins. If you don't "get this", I'm warning you now, you will either snap a thermal barrier or cause a leak where the nozzle and thermal barrier are not tight. You can be 1/2 turn one way or the other on the heater block as long as the nozzle does NOT bottom out against the face of the heater block.

[Jetguy]

Again, since you loosened yours, and you are basing everything on rotation of the heater block, you are at risk for a leak.
viewtopic.php?f=4&t=6191

Again, what you do is, you first screw the nozzle until it bottoms out against the heater block (the hex shoulder), then backoff by 1/4 to 1/2 turn back out. Then screw in the throat tube and heatsink by hand until you feel it make contact to the nozzle. You may have to adjust here to get an alignment setup, but the idea is, you still have room to tighten the nozzle into the heater block to ensure it pushes against the throat tube internally. This pressure both seals the nozzle to the tube, and also provides the friction to keep everything in place and not rotate.
Again, the way I do it, I put a bar into the heating rod hole, tighten the nozzle torquing to the heater block, and only with no more than light pressure, hold the throat and heatsink from spinning. This way, all the torque is in the nozzle, not the tube. If you try to tighten the throat side, it will snap off.