X-axis - hotend clearance

Hello members,

I have an i3 clone printer, and I was wondering if the relatively big clearance between the bottom of the X-axis bridge and the tip of the hotend has any practical purpose.



I'm positive that the bridge itself could lower itself all the way to the hotbed, so if i'd fasten the whole extruder assembly to the bridge so that the hotend tip would be just a few mm below the level of the bottom of the bearing, then i'd earn 3-4 cm of extra Z printing space. See the below PS image.



Any thoughts? Thanks.

Edited 1 time(s). Last edit at 01/17/2017 12:01PM by mortee.

You could start with the heatbarrier. Screw it up as much as possible until the throat almost touches the gear.

I'd be alarmed, when the heater block would be so close to the linear bearing. Maybe you can turn it around, so the heater element is in front of the nozzle?

Thanks for those considerations. My extruder assembly is designed in a way that the threaded pipe (is that the heatbarrier?) goes up to a specific height, and the hole's top opening is only as wide as the filament. Also, I'll look into how I could get the heater block further away from the bearing.

The question however, whether the clearing serves a practical purpose, is still open.

Edited 1 time(s). Last edit at 01/17/2017 12:04PM by mortee.

Yes its there to allow air to cool the heat break.
The heat break (threaded tube) has a small diameter so there is a very small cross section for the heat to pass through. And its long enough to allow the air to cool it before the remaining heat soaks into the extruder area. The heat sink at the extruder is also cooling the motor.
If you look at an E3D hot end it has fins on the heat break to aid cooling and can have a fan to increase airflow.

Quote
MCcarman
Yes its there to allow air to cool the heat break.

"It", as in what exactly?

The hot end clearance - as in your original post.

Without this gap your extruder will get hot, something most are not designed for, only the hot end should be hot,

Most extruders jam up with they get hot as the fitment is to hot to high and thus soft, so it goes everywhere vs down the hole its meant to.

I'm betting that it would be fine if you turned the hot end 90 degrees away from the bearing block. The excuse that the heat break would get too hot IMHO is bogus. Sorry. Just above the heat break is your aluminum block cooled by a large fan-cooled heat sink. That will suck some of the heat away from the heat break as usual to prevent molten plastic from getting into that area.

Try it and see. No big deal and you have a lot of space to gain.

---

Folger Tech 2020 i3 and FT-5 as well as modified JGAurora A5 with direct drive E3D/Titan. All running the BLTOUCH.
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Dust, MCcarman, I guess you both got me wrong. My concern isn't about the clearance between the extruder motor and the hot end itself. I would keep that totally intact. I meant the clearance between the bearing's bottom and the level of the hot end's tip. I plan on moving the whole assembly (together with motor, heat barrier and hot end) up relative to the bearings/bridge. So the only change would be that the X-axis beams would be much closer to the top layer being printed.

Edited 1 time(s). Last edit at 01/19/2017 09:54AM by mortee.

Anyway, turning around the heater block did the trick for moving it further away from the bearing, so that when the whole thing goes up, they don't touch.

Now the clearance looks better, but I'm afraid your part blower now cools the hot end? I've insulated mine with cotton wool pads ( demak up(R)) and Kapton tape.

Edited 1 time(s). Last edit at 01/20/2017 02:36AM by o_lampe.

OK, sorry I miss interpreted your question.
Your proposal should work. Note o_Lampe's point. Looks like plenty of clearance between the carriages at the end of the rails and the Z motor couplings.
Usually a good idea to clamp the wiring to the carriage (Pclip, tywrap etc) as the continuous flexing of the joints can cause failure. Might be possible to use one of the top bearing screws.
While you have it striped down. I suggest you take off the front cooling fan and cut a big hole in the metal behind it (I actually made a big slot). Refit the fan. This means you can remove the fan and see/access the extruder really easily.

Yes, I've examined everything, and there's no reason why the bridge couldn't lower a further 4 cm, aside from the extruder head itself.

For that matter, the metal behind the part cooling fan does currently have a huge hole cut in it. But I'll actually get rid of it entirely, as well as the metal part currently holding the extruder motor itself, as it is folded forward at the bottom of the bearings. With the new configuration, I'll need a horizontal platform for the motor somewhere around the middle of the sheet screwed to the bearings, so that would be a separate L section aluminium, also screwed. And I'll print a new frame/nozzle piece for the part cooling fan, so that it wouldn't need the vertical metal sheet folded up in front of the motor.

Appears to be good.



Edited 1 time(s). Last edit at 01/20/2017 04:29PM by mortee.