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Kjetilei
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Improved y-axis print width

Post by Kjetilei »

By redesigning the y-axis plastic parts and the top z-axis carrier it should be possible to utilize the full width of the rail to get a couple of centimeters extra print area (although this might make it more wobbly). currently the tensioning mechanisms and opto-switch vane "steals" a couple of centimeters of usable print area.

If redesigning the belt tensioning please make it more solid. I have broken bits on both parts trying to tighten the belt to remove some small wobbling of the belt around the pulley.
battle_scar_1.jpg
battle_scar_2.jpg

Kjetilei
Posts: 334
Joined: Fri Mar 16, 2012 8:26 pm
Location: Stavanger, Norway

Post by Kjetilei »

By moving the hotbed closer to the z-axis rail the minor wobbling that exists when wiggling the bed could be minimized and would also bring the guides (bearings) closer to the pulley resulting in less play on the belt. The y-axis opto switch could be placed on the other side of the rail and if the z-axis assembly is moved to the back the z-axis opto switch could be moved closer to the rail letting the limit switch vane clear the hot bed.

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gfeliksdal
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Post by gfeliksdal »

Kjetilei wrote:Since I'm experiencing some minor problems with x-axis vibrations due to friction issues I began to think about possible extruder assembly improvements:
- Lower weigh - simplified design with less/lighter metal parts and printed parts
- Lower COG (= move components down compared to current design) This should be achievable by rotating y-axis components 180-degrees (stepper in the top), redesigning the z-axis carrier parts to lower the bed and moving the electronics box away from the z-axis carrier
- Stepper moved closer to the x-axis rail and extrusion (not rotated as it is now)
- COG in the middle of the slider width-wise (= move stepper and hot end etc to the right) for less vibrations (?) when moving the extruder with high speed
What kind of vibrations do you experience? Did you use teflon/ptfe spray on the guides? This for me eliminated most vibrations. The slides are advertised as self lubricating, but the teflon spray makes them run a lot smoother. The only vibrations I notice are when one of the axes are traversing direction. But these are inherent to a dynamical system. I guess they can be further minimized by increasing stiffness of relevant parts. The suggestions you made can definitely help, I have to think about it.

The vibrations might reduce a little when moving the motor closer to the x-rail. I've rotated the motor, because it enables a slightly more compact build of the extruder assembly, at least what I've found till so far. Another benefit that the air which is sucked by the fan mounted to the airduct can flow more smoothly along the motor. This results in less noise and larger surface of which air flows along the motor, so the extruder motor will stay cooler. I haven't measured any difference, but it seemed logical to me.

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gfeliksdal
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Post by gfeliksdal »

Kjetilei wrote:By redesigning the y-axis plastic parts and the top z-axis carrier it should be possible to utilize the full width of the rail to get a couple of centimeters extra print area (although this might make it more wobbly). currently the tensioning mechanisms and opto-switch vane "steals" a couple of centimeters of usable print area.
I've been thinking about it in the past and indeed there might be 2 cm of extra work space in y-direction. I left it this way, because of cosmetic reasons. The goal was to keep everything under the table, this is difficult when the 2 cm extra are gained. Right now it is already a little outside the table, so 2 cm might not be a problem.
Kjetilei wrote:If redesigning the belt tensioning please make it more solid. I have broken bits on both parts trying to tighten the belt to remove some small wobbling of the belt around the pulley.
Battle scar 1, I've experienced before. But battle scar 2 is new to me :). Might be production error. I have checked the design and beefed up the battle scar 1 part, the flange is now twice as thick. I've also beefed up the parts for battle scar 2 a little bit. I'll upload the parts soon.

Kjetilei
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Location: Stavanger, Norway

Post by Kjetilei »

gfeliksdal wrote:What kind of vibrations do you experience? Did you use teflon/ptfe spray on the guides? This for me eliminated most vibrations. The slides are advertised as self lubricating, but the teflon spray makes them run a lot smoother. The only vibrations I notice are when one of the axes are traversing direction. But these are inherent to a dynamical system. I guess they can be further minimized by increasing stiffness of relevant parts. The suggestions you made can definitely help, I have to think about it.

The vibrations might reduce a little when moving the motor closer to the x-rail. I've rotated the motor, because it enables a slightly more compact build of the extruder assembly, at least what I've found till so far. Another benefit that the air which is sucked by the fan mounted to the airduct can flow more smoothly along the motor. This results in less noise and larger surface of which air flows along the motor, so the extruder motor will stay cooler. I haven't measured any difference, but it seemed logical to me.
Sorry Guillaume. I forgot to mention that I have yet to add PTFE-spray on the rail. I just got the spray and hope to do the kapton-tape modification and PTFE-spraying tonight.

One idea I meant to post was to rotate the air duct fan 45-degrees along the z-axis and 20-30-degrees along the y-axis for less use of plastic on the mounts and air duct. I would also like the air duct to be a little bit closer to the hot end (might cause a problem with heat) and 1 mm higher (I have experienced the air duct hitting printing parts and sanded the opening down a tiny bit).

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gfeliksdal
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Post by gfeliksdal »

Kjetilei wrote: Sorry Guillaume. I forgot to mention that I have yet to add PTFE-spray on the rail. I just got the spray and hope to do the kapton-tape modification and PTFE-spraying tonight.
No problem...please don't directly spray it on the rail, it will make a big mess. It is best to spray it on a q-tip and rub that agains the rail where the drylin/plastic parts make contact with the rail. I'm curious to the results
Kjetilei wrote: One idea I meant to post was to rotate the air duct fan 45-degrees along the z-axis and 20-30-degrees along the y-axis for less use of plastic on the mounts and air duct. I would also like the air duct to be a little bit closer to the hot end (might cause a problem with heat) and 1 mm higher (I have experienced the air duct hitting printing parts and sanded the opening down a tiny bit).
Ah ok, that could be better indeed. As for the airduct being closer and 1mm higher. When you mounted the fan + airduct onto the extruder base, did you file the surface to smoothen it a little? If you look at the printer from the front you might notice a gap between the airduct fan and the extruder base. This can be caused by and unfiled surface. When there is no gap the airduct will be closer to the hot-end and also less close to the bed. It is only a minor distance but should be sufficient.

Kjetilei
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Post by Kjetilei »

gfeliksdal wrote:I've been thinking about it in the past and indeed there might be 2 cm of extra work space in y-direction. I left it this way, because of cosmetic reasons. The goal was to keep everything under the table, this is difficult when the 2 cm extra are gained. Right now it is already a little outside the table, so 2 cm might not be a problem.
I think it is possible to come up with a design that does not protrude much more by bending the belt the opposite direction of the current design ("around" the end of the rail).
gfeliksdal wrote: Battle scar 1, I've experienced before. But battle scar 2 is new to me :). Might be production error. I have checked the design and beefed up the battle scar 1 part, the flange is now twice as thick. I've also beefed up the parts for battle scar 2 a little bit. I'll upload the parts soon.
I really tightened the screw when the plastic broke but was kind of surprised anyway :) Luckily it has not affected the ability to print. I have/had a problem with the belt wobbling a tiny bit on the pulley and wanted to tension the belt a bit more. I'll be waiting for the updated STLs :)

Kjetilei
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Post by Kjetilei »

gfeliksdal wrote:No problem...please don't directly spray it on the rail, it will make a big mess. It is best to spray it on a q-tip and rub that agains the rail where the drylin/plastic parts make contact with the rail. I'm curious to the results
I'll use your nice tutorial.
gfeliksdal wrote:Ah ok, that could be better indeed. As for the airduct being closer and 1mm higher. When you mounted the fan + airduct onto the extruder base, did you file the surface to smoothen it a little? If you look at the printer from the front you might notice a gap between the airduct fan and the extruder base. This can be caused by and unfiled surface. When there is no gap the airduct will be closer to the hot-end and also less close to the bed. It is only a minor distance but should be sufficient.
Consider me guilty :oops: I could have filed the part a little bit better but I only had a small file available and didn't think about the air duct being so close to the level of the hot end tip. Luckily I love to learn from my mistakes since I do them often enough...

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gfeliksdal
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Post by gfeliksdal »

Kjetilei wrote: I think it is possible to come up with a design that does not protrude much more by bending the belt the opposite direction of the current design ("around" the end of the rail).

That indeed could be an option. Only downside is that it is more difficult to remove the slider from the rail if needed. And also have to check if the extra belt length is still ok.
Kjetilei wrote:I really tightened the screw when the plastic broke but was kind of surprised anyway :) Luckily it has not affected the ability to print. I have/had a problem with the belt wobbling a tiny bit on the pulley and wanted to tension the belt a bit more. I'll be waiting for the updated STLs :)
Ah ok,now I understand how it broke. Did you kept tightening the screw when the bolt-head touched the plastic part? If that's true, than you were squeezing plastic between a bolt-head and the nut made of steel :)...without actually tensioning the belt. In that case the stronger dimensioned part will also break, when you keep tightening it.

Kjetilei
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Location: Stavanger, Norway

Post by Kjetilei »

gfeliksdal wrote:
That indeed could be an option. Only downside is that it is more difficult to remove the slider from the rail if needed. And also have to check if the extra belt length is still ok.
I think it could be possible to not bend around the rail on the "non-tensioning" side but instead tension the belt against the side of the rail and saving 2cm of belt but this would not get us the full potential of the rail length. If instead you do a quite sharp bend around the rail you could design a solution that should not use any more belt than the current design. The bend could also be designed with a profile matching the belt for extra gripping power on the non tensioning-side.
gfeliksdal wrote: Ah ok,now I understand how it broke. Did you kept tightening the screw when the bolt-head touched the plastic part? If that's true, than you were squeezing plastic between a bolt-head and the nut made of steel :)...without actually tensioning the belt. In that case the stronger dimensioned part will also break, when you keep tightening it.
The bolt-head did not touch the plastic. I think it must have been caused by a sideways-working force. Either from me screwing in the screw with to much "movement" or due to forces working on the bolt from the tensioning part being pulled sideways by the highly tensioned belt. Your beefed up part should solve this :)

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