March 26, 2019, 04:55:43 am

News:

SMF - Just Installed!


+-

User

Welcome, Guest.
Please login or register.
 
 
 
Forgot your password?

Stats

Members
Total Members: 52
Latest: weed2all
New This Month: 0
New This Week: 0
New Today: 0
Stats
Total Posts: 1604
Total Topics: 166
Most Online Today: 7
Most Online Ever: 169
(October 30, 2018, 10:03:43 am)
Users Online
Members: 0
Guests: 8
Total: 8

Theme Select

*

Search



Advanced Search

Z carriage theory

Started by Hozza, May 12, 2018, 01:25:55 pm

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

Hozza

This is something I've been thinking about and I can't seem to work it out.

So if you have 2 lead screws to raise Z but you only want to use one motor, then it's obvious you need to run the lead screws via a belt and pulley system.

How on earth do you work out the steps?
Which type of motor?
Pulley size?

Required to give good hold torque and good step resolution?

Cheers
Paul
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

shawdreamer

it doesnt matter what size pulley you use or how many teeth they have (which effects steps in certain circumstances) aslong as you use the same size on both lead screws then both screws will advance at the exact same speed.

for example I did just as you surmised with my first reprap design and simple had one motor directly powering one lead screw with a gt2 36 tooth pulley on its top, this in-turn was connected via a belt to an exactly the same 36 tooth gt2 pulley on the top of the un-powered lead screw on the opposite side of the printer, worked a treat till the earlier form of 6mm belts began to stretch over time and the lead screws fell out of sync, later belts are better reinforced with steel thread so dont succumb to stretching that easily nowadays.

as for torque, generally a single motor can cope with raising z axis alone aslong as the pulley system between the two leadscrews isnt under to great a torsion (eg if the jointing belt is overly taught)
Geeetech Prusa i3 pro-B (ABS Workhorse)
Pultur Prusa (my own design)
Poltur XL (my own "MUST BE BIGGER" design)
Poltur XL v.2 (my own "MUST BE BIGGER STILL, MUST USE EXTRUSION" design)
https://www.thingiverse.com/shawdreamer/designs

Hozza

May 12, 2018, 09:06:40 pm #2 Last Edit: May 12, 2018, 09:09:41 pm by Hozza
Thanks for you input mate, it's great when a community can share knowledge and help each other ~~

Well I had thought if all pulleys were the same size then theoretically I'm keeping a 1:1 ratio so only have to work out the steps required for the lead screw movement. But I'm not entirely sure.
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

Doug

May 13, 2018, 09:23:49 am #3 Last Edit: May 13, 2018, 09:30:52 am by Doug
Quote from: Hozza on May 12, 2018, 09:06:40 pm
Thanks for you input mate, it's great when a community can share knowledge and help each other ~~

Well I had thought if all pulleys were the same size then theoretically I'm keeping a 1:1 ratio so only have to work out the steps required for the lead screw movement. But I'm not entirely sure.


Paul

It may be worth checking this vid  https://www.youtube.com/watch?v=v3Xnb0XzlAs  from about 7:50 in Ian's large CoreXY with a bed that weighs around 6kG uses 3 lead screws driven from a single Nema17?

Also worth reading his blog post re Leadscrews as well  https://somei3deas.wordpress.com/2017/01/31/z-axis-lead-screws/ 

Oh and I would advise against using the steel cored belts the cores work harden and snap causing massive stretch in the belt just ask Rommie.

shawdreamer

I should have been a bit more precise in regards to the reinforced belts, I didnt mean the low grade types that are way way WAY to rigid and dont like to bend atall due to the steel threads in them being pretty crappy spec (even some of the pricey stuff is like that tbf).

its hit and hope usually but Ive found the steel thread belts that are made with the softer more flexible compounds are pretty reliable, its what I use, only thing is you often dont know if youve got a decent one till it drops onto your mat :rolleyes:
Geeetech Prusa i3 pro-B (ABS Workhorse)
Pultur Prusa (my own design)
Poltur XL (my own "MUST BE BIGGER" design)
Poltur XL v.2 (my own "MUST BE BIGGER STILL, MUST USE EXTRUSION" design)
https://www.thingiverse.com/shawdreamer/designs

Doug

Quote from: shawdreamer on May 13, 2018, 10:07:36 am
I should have been a bit more precise in regards to the reinforced belts, I didnt mean the low grade types that are way way WAY to rigid and dont like to bend atall due to the steel threads in them being pretty crappy spec (even some of the pricey stuff is like that tbf).

its hit and hope usually but Ive found the steel thread belts that are made with the softer more flexible compounds are pretty reliable, its what I use, only thing is you often dont know if youve got a decent one till it drops onto your mat :rolleyes:


This of course is very true and if your using it for a set of threaded rods then it also needs to be a closed loop built And I would be looking at Genuine Gates belts to be honest prob is finding them at a sensible amount of money I don't really want to shell out £10 a meter for 6mm belts plus I really want to go to 9mm for the CoreXY Build (2.5-3 meters of belt on each side). another important thing to consider on the Z Leadscrews is to keep the lead as low as you can and avoid those awful ones that are common place (TR8x8 which are 2mm pitch 4 start (giving an 8 mm Lead) so the thread angle is very high which needs more holding torque else the Z will drop)
there no so bad in a I3 style printer but if they are moving the complete bed assembly they just aren't suitable IMHO

Hozza

Thanks for the input...

Doug I had already decided on TR8*2, I have either got to run the pair with the motors in parallel (which can cause a step jump issue when powering up the duet 0.6 I have read) or one and drive them via a belt system.

Definitely look at gates belts if I go that route.
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

Doug

May 13, 2018, 10:53:48 am #7 Last Edit: May 13, 2018, 10:57:12 am by Doug
Quote from: Hozza on May 13, 2018, 10:50:50 am
Thanks for the input...

Doug I had already decided on TR8*2, I have either got to run the pair with the motors in parallel (which can cause a step jump issue when powering up the duet 0.6 I have read) or one and drive them via a belt system.

Definitely look at gates belts if I go that route.


yes do are you aware of how to calculate the belt length you need?

Also the Uk sellers for Gates Belts are  http://www.brammer.co.uk  and they have branches all over the country.

I was going to use a belt system on mine but am now going with 3 independent motor and let the firmware deal with it.

Hozza

Not yet, but it's early days in the design process.
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

Gaza07

May 13, 2018, 11:00:30 am #9 Last Edit: May 13, 2018, 11:05:15 am by Gaza07
Isnt there a plan or something that can be followed I was thinking about maybe doing one of these  :shrug:
did I read that you had used a smart effector on yours Doug ?
what are the benefits of a corexy printer hmmm maybe I should start a new topic  :rolleyes:

Ive started a new topic for this seeing as I know nothing about them and dont want to hijack this thread ~~
Custom built delta with Flex3Drive Gen 4 / Duet Electronics 330mm build area
Custom built delta with Flex3Drive Gen 4 / Duet Electronics 180mm build area
AnyCubic 4max XY printer 210x210x300 build area
AnyCubic Kossel Mini 180x180x300 build area
Geetech A10M Dual Colour 220x220x260 build area
Kelant Orbeat D100 DLP/SLA

http://www.multi-rotor.co.uk
https://www.thingiverse.com/Gaza07/about

Hozza

May 13, 2018, 11:08:18 am #10 Last Edit: May 13, 2018, 01:57:19 pm by Doug
I'm basing mine around the HEVO, I've built a corexy before I wanted a small printer and I went too small so sold it.

As for benefits I have no idea just want something different  :laugh:

Sorry should have gone in my own post rather than this deleted and will raise a new one
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

Doug

Quote from: Hozza on May 13, 2018, 11:08:18 am
I'm basing mine around the HEVO, I've built a corexy before I wanted a small printer and I went too small so sold it.

As for benefits I have no idea just want something different  :laugh:

Sorry should have gone in my own post rather than this deleted and will raise a new one


Paul if useing just 2 led screws then take the number of teeth on one pulley add that to the distance between the 2 screws and double it that will give you the number of teethe required in the belt but you may be better looking at going with 3 lead screws so the they form a plane rather that a pivot for the bed (one of the downsides of the Hevo design and many others for that matter the best design out there at the moment is probably the Voron2 but that gets expensive needing 7 drivers 7 motors 7 linear rails etc of and a controller that can cope with 4 motor independent labelling for the Z axis) don't get me wrong the Hevo is prob the best low budget one out there and def avoid the Dbot.

found this pic which might help visualise the belt type arrangement for triple lead screws  https://drive.google.com/drive/folders/1Jc2AcITe95_gTiPdj9hKV0gQ9_7zY80U  pic 11 is the one you want but the others are good as well

Hozza

Cheers for that Doug, good to know the HEVO is a good choice. Must admit I wouldn't mind getting my hands on some of the STL files for the zbot.
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)

Doug

Quote from: Hozza on May 13, 2018, 02:29:53 pm
Cheers for that Doug, good to know the HEVO is a good choice. Must admit I wouldn't mind getting my hands on some of the STL files for the zbot.


Hang on I think he has published them if not I am sure he will pass them on
this is the post on the duet forum  https://forum.duet3d.com/topic/5282/my-custom-d-bot just ask him in the thread for any custom ones he did on top of the std.

Hozza

I've asked if he is going to release them
Makibox (sold)
i3 custom build (sold)
Smartcore (sold)
Kossel XL Duet3D based, with Flex3drive (working)
HEVO Hybrid (worlds slowest build)
Kossel Mini Duet3D based, with Flex3drive (working)
Geeetech A10M (Still in Box)


SMF Gallery Random Image

Powered by EzPortal