Pros and cons um2 hotend vs umo
Posted: April 17th, 2016, 7:09 pm
Well I been doing a lot of adjustments to the slicer settings to finally set my um2 hotend on a production ready state and I want to share my findings, since I think this wasn't done before.
This it's the same object, printed at the same speed on2 machines. Oiled, cleaned and with very good umo+ gt2 belts and misumi shafts.
At first sight everything looks ok on both.
Lets check the umo+ and look at the 2 of the 27
More about that gap later. I finally found what makes the umo+ suck a bit (and we should design something to fix it)
Ok now um2
So, um2 looks better at doing flat layers (it really does) but... (ok more about this later)
So. First of all umo temp was 210, um2 had to be 220. But not because I can't print at 210, but because on um2 hotend at 210 this happens.
Check from left to right 210-215-220C using faberdashery pink.
To get the glossy 'on' on um2 I must print 10-15C higher than umo. Ok this might be the pt100 but also, I can print at 210C without any feeder problem. And on umo I never got this matte effect not even at 185C. So it's weird but I have this effect on faber pla's (mint, blue, pink, vanilla). So I think must be because the hotzone of um2 hotend it's just smaller (umo hotzone it's almost 2-3 times longer).
Ok. The last VERY weird stuff.
Check this ringing effect. Left umo+ Right um2
Remember that both machines have the same slideblocks, misumi shafts, gt2 and they where cleaned and oiled today. And both machines used the same spool, and both have the same aceleration/yerk settings and even the same IRobertI umo feeder motors with mk7.
I think the wood of the umo hotend absorbs part of the vibration (makes sense?) and also since umo frame acts/vibrates like a guitar, the ringing effect on um2 hotend it's bigger.
Has anyone ever tested a umo+ hotend on a um2 frame to check this?
Ok now back to that top layers.
I been going bananas with this issue since I saw that um2 could do an almost perfect second top layer.
If you have an umo/umo+ you know that the hotend area, that has the peek/ptfe wood pushing down the coupler, has a gap of 0.2-0.5mm that you can't remove because that would crush your coupler and make a lot of problems. Well. This gap tilts the hotend by a very very small angle. Making worse toplayers. You can compensate with heat, etc. but the hotend will always be tilt (to solve this I must print one extra top layer and that's more filament & time). And that's why um2 hotend does better toplayers, because it isn't tilted. Easy way to fix? Make spacers for the 4 points of the wood, and one of that 4 should have his height lowered by the same amount of the gap. This should fix the wood/aluminium peek holder/hotend Tilt. I need to actually design something for that because you can level the bed to be like the 4axes but you can't compensate the hotend tilt unless you crush the coupler, and that's a really bad idea since it would bend and die sooner.
So guys, what do you think?
This it's the same object, printed at the same speed on2 machines. Oiled, cleaned and with very good umo+ gt2 belts and misumi shafts.
At first sight everything looks ok on both.
Lets check the umo+ and look at the 2 of the 27
More about that gap later. I finally found what makes the umo+ suck a bit (and we should design something to fix it)
Ok now um2
So, um2 looks better at doing flat layers (it really does) but... (ok more about this later)
So. First of all umo temp was 210, um2 had to be 220. But not because I can't print at 210, but because on um2 hotend at 210 this happens.
Check from left to right 210-215-220C using faberdashery pink.
To get the glossy 'on' on um2 I must print 10-15C higher than umo. Ok this might be the pt100 but also, I can print at 210C without any feeder problem. And on umo I never got this matte effect not even at 185C. So it's weird but I have this effect on faber pla's (mint, blue, pink, vanilla). So I think must be because the hotzone of um2 hotend it's just smaller (umo hotzone it's almost 2-3 times longer).
Ok. The last VERY weird stuff.
Check this ringing effect. Left umo+ Right um2
Remember that both machines have the same slideblocks, misumi shafts, gt2 and they where cleaned and oiled today. And both machines used the same spool, and both have the same aceleration/yerk settings and even the same IRobertI umo feeder motors with mk7.
I think the wood of the umo hotend absorbs part of the vibration (makes sense?) and also since umo frame acts/vibrates like a guitar, the ringing effect on um2 hotend it's bigger.
Has anyone ever tested a umo+ hotend on a um2 frame to check this?
Ok now back to that top layers.
I been going bananas with this issue since I saw that um2 could do an almost perfect second top layer.
If you have an umo/umo+ you know that the hotend area, that has the peek/ptfe wood pushing down the coupler, has a gap of 0.2-0.5mm that you can't remove because that would crush your coupler and make a lot of problems. Well. This gap tilts the hotend by a very very small angle. Making worse toplayers. You can compensate with heat, etc. but the hotend will always be tilt (to solve this I must print one extra top layer and that's more filament & time). And that's why um2 hotend does better toplayers, because it isn't tilted. Easy way to fix? Make spacers for the 4 points of the wood, and one of that 4 should have his height lowered by the same amount of the gap. This should fix the wood/aluminium peek holder/hotend Tilt. I need to actually design something for that because you can level the bed to be like the 4axes but you can't compensate the hotend tilt unless you crush the coupler, and that's a really bad idea since it would bend and die sooner.
So guys, what do you think?