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compact carrier for Kossel Deltas

Posted by o_lampe 
Re: compact carrier for Kossel Deltas
November 22, 2017 02:12AM
Good idea. The only reason I haven't is that I didn't want any printed structural parts on this machine. But I suppose a printed block wouldn't flex much given the screws are supporting it.

Edited 2 time(s). Last edit at 11/22/2017 09:31AM by DjDemonD.

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Re: compact carrier for Kossel Deltas
November 22, 2017 09:09AM
Flexural modulus of ABS is about 2.25 GPa. Aluminium has it at 68 GPa.
The ability to resist deflection grows with the third power of thickness.
If there is enough space so that you can make your ABS part about 3.3 times thicker (compared to the aluminum original) then it will have the same ability to resist bending. Maybe make it about 4.1 times thicker since 3D printed ABS will we weaker than injection molded ABS.
Flexural modulus of PLA is about 4 GPa. If you print in PLA it should be enough to make it 2.6 - 3.3 times thicker than the aluminum original.
Just some rough numbers smiling smiley
Re: compact carrier for Kossel Deltas
November 22, 2017 02:15PM
Quote
DjDemonD
One of the 4 screw holes in the linear rail carriage now sports a 25mm M3 screw, which both sides of my belt are fixed to, with a twist for the top pulleys, so that as DC said the tension is carried by the belt

It looks like there're small gaps above and below the screw that's between the belt. Is there any movement there?
Re: compact carrier for Kossel Deltas
November 22, 2017 02:31PM
If you mean the gap between screw and the first cable tie it doesn't seem to be any issue as the belts are pulling with equal force on both sides of the screw. The machine calibrates to 0.005 dev so I presume there can't be any mechanical issues.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
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Re: compact carrier for Kossel Deltas
November 22, 2017 02:45PM
Just thought there might be a bit of vertical play, but the screw is probably squeezed into teethes on both sides and won't go anywhere. Good idea.
Re: compact carrier for Kossel Deltas
November 22, 2017 02:48PM
Ahh I see. It probably does not show but there is an m3 nut tightened against the carriage at the base of the screw to ensure it doesn't rock back and to.

Edit- having just written that, distinctly having a recollection of placing the nut there, I just looked at the printer and there are no nuts. But there should be, I might put some there next time I change the belts.

Edited 1 time(s). Last edit at 11/22/2017 02:50PM by DjDemonD.

[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
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Re: compact carrier for Kossel Deltas
November 22, 2017 11:43PM
Thanks for sharing the belt attachment for the smart effector. I might copy it on my "deluxe" Delta.

I played around with dc42's tip to turn around the belt on the idler side and I came up with a simple ( but maybe too weak ?) solution:
I cut the belt in two pieces and CA-glued them teeth-to-teeth. Now I have a part with a smooth part for the idler side and a driver side, with teeth inside.

I tried to rip it apart, but the CA glue does a really good job here.
This slim design even fits in the 2020 slot ( which was my major concern ). Just have to make sure the glued pieces don't have to run over the idler.

If I ever replace the belts on my CoreXY, I try to do it there too. There are way more idlers to deal with.
Re: compact carrier for Kossel Deltas
November 22, 2017 11:49PM
Quote
hercek
Flexural modulus of ABS is about 2.25 GPa. Aluminium has it at 68 GPa.
The ability to resist deflection grows with the third power of thickness.
If there is enough space so that you can make your ABS part about 3.3 times thicker (compared to the aluminum original) then it will have the same ability to resist bending. Maybe make it about 4.1 times thicker since 3D printed ABS will we weaker than injection molded ABS.
Flexural modulus of PLA is about 4 GPa. If you print in PLA it should be enough to make it 2.6 - 3.3 times thicker than the aluminum original.
Just some rough numbers smiling smiley

If I read your explanation correctly, I could make the aluminum clamp much thinner than the PETG version. ( given that the PETG version is already strong enough)
But then I thought, it might be the rubber belt teeth which can only withstand so much belt tension and I have to use the same size aluminum clamp to get enough teeth "involved"?

Edited 1 time(s). Last edit at 11/22/2017 11:50PM by o_lampe.
Re: compact carrier for Kossel Deltas
November 23, 2017 01:55AM
Yes, you can make aluminum parts thinner by the same factor. Notice this is about thickness in the direction of force trying to bent a part.

If one is concerned about stretching then it is analogous but one needs to use Young's modulus instead of Flexural modulus and cross-section area instead of the third power of thickness.

Flexural modulus is about equal to Young's modulus for isotropic materials (like e.g. aluminum) but there are significant differences for some materials (like e.g. plastics).

As for as connecting belts: the belt manufacturer specifies the minimum number of teeth which must mesh. I do not know what it is. Probably somewhere around 8. I use open loop belts and just twist one side by 180°. Works fine.

Flexural modulus: [en.wikipedia.org]
Young's modulus: [en.wikipedia.org]
Re: compact carrier for Kossel Deltas
November 23, 2017 11:10AM
Eight teeth would be good, because I have 2x5 teeth involved now. The cutouts are now placed where the beefy part of the clamp is.
I also added two M3 screwholes. That way the rods are separated from the slider clamp and I could use them as belt tensioners, too. ( in case 5 teeth are strong enough )


Re: compact carrier for Kossel Deltas
November 27, 2017 12:05AM
Read
Quote

By reading the headline again, I got a crazy idea: Why not built a smaller plugin delta inside the big delta?

Say, you have a big delta with dual shaft steppers and the bed is removable.
Wouldn't it be nice to use the rear stepper shaft to drive a smaller Delta with it? ( given, that the smaller Delta is more accurate than the big one )
You would have to remove the bed, plugin the bottom-less frame of the small delta ( with it's own rods, effector, bed, endstop and hotend ) and go on from there.
Both printers share the bottom frame with electronics and steppers. You just have to design some inner corners to plugin the small towers.

It started as a funny/crazy idea, but during the weekend I checked my Kossel XL and it would be possible to fit a 200mm dia Delta inside the XL frame.
That would probably be the cheapest Delta ever, since they share the steppers and the electronics ( DuetWifi ). In my case, the XL bed wouldn't have to be removable, since my XL delta is built upside down ( steppers on top )
I don't know if the compact carrier would be more accurate than the big Delta with linear rails, but it could carry a laser-engraver or a small nozzle mini hotend to repurpose the frame for more than one task.
I wanted to build two prototypes anyway. One 2020 standalone and the H-profile compact carrier will be implanted into the Kossel XL.

Edited 1 time(s). Last edit at 11/27/2017 12:49AM by o_lampe.
Re: compact carrier for Kossel Deltas
November 27, 2017 12:42AM
Was shopping for NEMA17 dual shaft steppers with 0.9°, but couldn't find any. sad smiley
Has anyone seen one? (1.5-2A will do )
Re: compact carrier for Kossel Deltas
November 27, 2017 12:50AM
I got some made by wantai motor I just emailed them and gave them the specs I wanted they barely cost more than off the peg motors.

Any chance of a sketch of the idea above I can't visualise it.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
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Re: compact carrier for Kossel Deltas
November 27, 2017 04:23AM
Just a quick sketch.
You can see the outer XL frame, the steppers with dual shaft and the inner frame driven by the rear pulleys.
The outer carriers/rods are smart effector/magarms, easy to remove.
The bed ( in my case ) is at the top. In other cases, it has to be replaced by the smaller bed.



I call it the Matrioska-Delta winking smiley

How long did it take to get the dual shaft,0.9° steppers? Waiting for parts can be soo annoying, especially because I have plenty of spare time until Jan. 2018.
Downgrading to 1.8° would make both Deltas less accurate, don't you agree?

Edited 2 time(s). Last edit at 11/27/2017 04:38AM by o_lampe.
Re: compact carrier for Kossel Deltas
December 13, 2017 12:39AM
I finally got the frame assembled and running. There is a little squeaking noise from one off the carriers. The belt clamp is rubbing inside the T-slot ( can be fixed ). The belt can now be tightened by two screws on the carrier.
The rods I had laying around are a bit to long for the frame. I only have ~130mm Z-height, also the rods bind quite early. That's partly due to being almost vertical, but also because the upper rod ends are in line with the Delrin mushroom sliders. If I'd move them a few mm to the inside, they could move freely. But that would add a lever to any wiggle in the slider.



Video link
Re: compact carrier for Kossel Deltas
December 22, 2017 12:45AM
Is there a 1:1 replacement for Traxxas rod ends?
I had one major head crash yesterday, because I lowered the probe relative to the nozzle, but forgot to change "homed height" in config. Now the whole effector is loose and I hear many of the rod ends rattling while it moves.

Before I had this accident, I got pretty good results in mesh bed leveling and auto configuration. ( deviation 0.018 )

Edited 1 time(s). Last edit at 12/22/2017 12:49AM by o_lampe.
Re: compact carrier for Kossel Deltas
December 22, 2017 01:13AM
if you you intend to use a standard E3Dv6 hot end, you might consider magnetic rods + Smart Effector. It's not a 1:1 replacement, but it shouldn't be difficult to re-print your sliders with a flat area on top and mounting holes in a 20mm square for the carriage adapters.

When I make substantial changes or I test experimental firmware, I temporarily reduce the motor current, to reduce damage in the event of a head crash.


Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: compact carrier for Kossel Deltas
December 22, 2017 01:18AM
+1 for magnetic rods, though be aware there are big differences in the way the two competing systems work. The one like Haydn Huntly's system with magnets in the rods, works a lot better than the magnets in the carriages/effector. Its a bit counterintuitive but I've tried both and would not advocate the latter.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: compact carrier for Kossel Deltas
December 22, 2017 10:44AM
I have a smart effector waiting for his call of duty, but the mag arms are 360mm from T3P3.
Unfortunately Haydn Huntley isn't easy to contact, at least for me who boycotts cooggle and fasebokk.

Any idea where to get shorter mag arms ( 250mm-ish ), Huntley style?
If I had a lathe, I'd try making my own..
Re: compact carrier for Kossel Deltas
December 22, 2017 12:08PM
I can give you Haydn's email if you want it.

The T3P3 ones are his he supplies them.

But you could shorten them with some larger carbon tubes, epoxy and a jig.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: compact carrier for Kossel Deltas
December 29, 2017 07:42AM
I shortened the rods and repaired the cracked ends. Mag arms will take a while to arrive.
Although the effector is too loose for my liking, I still had pretty good mesh bed results.
The rest of the setup is very basic too, but the twisted vase came out pretty well.
A few gaps in the wall, I blame the dangling extruder for it.


I also made a short video of it, only worth looking if you are curious about the dangling part winking smiley

Video Link
Re: compact carrier for Kossel Deltas
January 02, 2018 01:00AM
I redesigned the beltclamp, because the rods were binding to early. The target printable radius is at least 100mm, but I was stuck at 60-70mm.
The rod ends are still very close to the belt- and slider axis, so any play won't have a huge lever to spoil the output.
I have to replace them and see what I get. The print quality is pretty good already...


Re: compact carrier for Kossel Deltas
January 02, 2018 01:38AM
Quote
DjDemonD
I will probably get critiqued for this, but with my PCB carriages on my kossel XL, I do not have robotdigg carriages or anything like that on top of them, that's unnecessary complexity and mass. One of the 4 screw holes in the linear rail carriage now sports a 25mm M3 screw, which both sides of my belt are fixed to, with a twist for the top pulleys, so that as DC said the tension is carried by the belt. Ill append an image later.

As for tensioning, I have printed inline tensioners, which work great on deltas as there is so much "spare" belt below the carriages which does not interfere with anything in use that you don't get on corexy's/cartesians, although I'd like to use them there also, as its just one twist of a screw to tension.

[attachment 99816 20171121_22265601.jpg]

Come to think about it, the robotdigg aluminium carriage is probably unnecessary if you're using the smart effector. Don't even know why I bought it.
Re: compact carrier for Kossel Deltas
January 02, 2018 01:48AM
Well, they were shown with it as a way of holding the belts, but they're quite an expensive belt clip. Still, they sell well.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
Re: compact carrier for Kossel Deltas
January 02, 2018 04:16AM
Quote
DjDemonD
Well, they were shown with it as a way of holding the belts, but they're quite an expensive belt clip. Still, they sell well.

I used the Robotdigg carriages in my design because I had them already. They are overkill when using the Smart Effector, but they have a nice built-in belt tension adjusters.

Edited 1 time(s). Last edit at 01/02/2018 04:18AM by dc42.

Delta printer calibration calculator, mini IR Z probe, and colour touch screen control panel: [escher3d.com]

Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

Disclosure: I have a financial interest in sales of the Panel Due, Mini IR height sensor, and Duet WiFi/Duet Ethernet [www.duet3d.com].
Re: compact carrier for Kossel Deltas
January 02, 2018 05:18AM
Just to be clear when I said "they sell well" , I mean if they're surplus to your requirements sell them on.


[www.precisionpiezo.co.uk] Accurate, repeatable, versatile z-probe plus piezo discs, endstop cables, pt100, 50w heaters.
[www.facebook.com] we want to see your first layer photos... give us a like/share
[www.thingiverse.com] DemonDeltaMicro - Micro Delta Printer & Things I've made/remixed.
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