Mendel90 Dibond with GT2 Pulleys/belt

Hello Nophead,

I am starting to gather all parts to build a mendel90

I would like to use aluminium GT2 pulleys 20 teeth and corresponding GT2 belt.

I saw in your github files that the mendel90 with dibond frame is using T2.5 pulleys 16 teeth and belts.

I would like to know if I have to print new stl's parts with my GT2 pulleys .
I yes, how should I proceed : which scad files will ne yo be changed and how ?

Or will I have only to reflect these new GT2 pulleys in the firmware of my ramps 1.4 ?

Thanks and Best Regards

Yes the STLs for the X carriage and belt clips and the Y belt anchors and clips will change. If the belt is a different thickness, or the pulley has a different radius the Y bar clamps will also change to align the bars with the centre of the belt.

To make the changes you would need to create new belt and pulley definitions in the corresponding vitamin files and use them in the config.

If they are 20 tooth pulleys with a pitch of 2mm then the firmware is the same as 16 tooth with pitch 2.5.

---

[www.hydraraptor.blogspot.com]

Hello Nophead,

Thanks for your explanations

I am not a python progammer, so that's why I opened this thread and asked for your help

I looked at he two files in the vitamins directory

The belt thickness is 1.33 mm
So I suppose that the parameters that would go into "belts.scad" would be

GT2 =[2.0, 6, 1.33];

Concerning the change for the GT2 pulley , it appears more difficult by looking at the file
pullies.scad

T2p5x16_metal_pulley= ["T2.5", 16, 12.16, 12.16 / 2 - 0.8, 8, 16, 5.7, 5, 16.0, 1.0, 6, 3.75, [0, 0,1.3], 0, M4_grub_screw];


function pulley_type(type) = type[0];
function pulley_teeth(type) = type[1];
function pulley_od(type) = type[2];
function pulley_ir(type) = type[3];
function pulley_width(type) = type[4];
function pulley_hub_dia(type) = type[5];
function pulley_hub_length(type) = type[6];
function pulley_bore(type) = type[7];
function pulley_flange_dia(type) = type[8];
function pulley_flange_thickness(type) = type[9];
function pulley_screw_length(type) = type[10];
function pulley_screw_z(type) = type[11];
function pulley_offset(type) = type[12];
function pulley_nut_y(type) = type[13];
function pulley_screw(type) = type[14];

Can you explain what are the :
function pulley_od(type) = type[2];

function pulley_ir(type) = type[3];

function pulley_hub_dia(type) = type[5];

function pulley_hub_length(type) = type[6];

function pulley_bore(type) = type[7];

function pulley_flange_dia(type) = type[8];

function pulley_flange_thickness(type) = type[9];

function pulley_screw_length(type) = type[10];

function pulley_screw_z(type) = type[11];

function pulley_offset(type) = type[12];

function pulley_nut_y(type) = type[13];

function pulley_screw(type) = type[14];

If you have a picture of Pulley T2.5 with showing above numbers, I will figure out about which one to replace for GT2
pulley

Best regards,
JC

The code is OpenScad, not Python.

pulley_od is the outside diameter of the teeth. pulley_ir is the inside diameter of the teeth. The rest should be self explanatory. type[0] is the first item in the list, type[1] the second, etc.

---

[www.hydraraptor.blogspot.com]

The rest should be self explanatory.

You are the designer of Mendel90
You are native english

I am french so If I ask you about the meaning of following items , it's because it is not "self axplanatory" for me


function pulley_hub_dia(type) = type[5];

function pulley_hub_length(type) = type[6];

function pulley_bore(type) = type[7];

function pulley_flange_dia(type) = type[8];

function pulley_flange_thickness(type) = type[9];

function pulley_screw_length(type) = type[10];

function pulley_screw_z(type) = type[11];

function pulley_offset(type) = type[12];

function pulley_nut_y(type) = type[13];

function pulley_screw(type) = type[14];


I feel like I am bothering you with my questions
It was not my intent at all
My intention was just change correctly the pullies.scad file

1)If you can attach a picture of the T2.5 pulley with the above measures , It will become selft explanatory for me

2)If not I would like some explanations about these numbers to change

3)If you think I am asking too much help to you , then tell it to me .

I will understand

I found a picture with detais about GT2 pulley 20 teeth

[www.aliexpress.com]

Is pulley_hub_dia 12,2mm ?

Is pulley_hub_length 7.5mm ?

Is pulley_flange_dia 16mm ?

pulley_screw_z : is z corresponding to screw length ?

pulley_offset : what is the this "offset" between what and what ?

pulley_nut_y : what is nut_y meaning ?

Thanks for your great help Mr Nophead

Edited 2 time(s). Last edit at 06/01/2013 09:06AM by koumac.

Sorry but it is too much work for me to make a diagram or translate into French. I spend nearly all the time I am awake and not eating trying to keep up with orders for kits.

For example "pulley_flange_thickness" is the thickness of the flange of the pulley. I can't see how I can explain that further in English. Similarly all the other names as self explanatory to an English speaker I would hope.

---

[www.hydraraptor.blogspot.com]

Mr Nophead,

Hey are you kidding or what ?

I didn't ask you to translate in french anything ! So please don't exagerate !!

I repeat that I am not native english
So , there are some english techical terms which are not easy to understand for me
Is that difficult to understand ?

I found a diagram of the GT2 pulley to try to figure out what are the terms in your scad file for the pulley

Did I ask you for a quick answsers ?

The only things which I m not sure and ask are about 5 terms

I didn't ask you about pulley_flange_thickness" ???? No !!!

So here remains only 5 easy questions in english for you , when ever you have some time to answer.....

Are those questions too difficult to answer ?Please tell me

According to the picture I attached [www.aliexpress.com]

1)Is pulley_hub_dia 12,2mm ?

2)Is pulley_hub_length 7.5mm ?

3) pulley_screw_z : is z corresponding to screw length ?

4)pulley_offset : what is the this "offset" regards to what ?

5)pulley_nut_y : what is nut_y meaning ?

If somebody else reading this forum can help me I will really appreciate also

Edited 2 time(s). Last edit at 06/01/2013 12:44PM by koumac.

Quote

I didn't ask you about pulley_flange_thickness" ???? No !!!

Yes you did

Quote

I am french so If I ask you about the meaning of following items , it's because it is not "self axplanatory" for me
...
function pulley_flange_thickness(type) = type[9];
...

1) No pulley_hub_dia is the diameter of the hub, which is 16mm on that page.
2) No it is 16mm - 7.5mm minus the flange thickness on the diagram but the picture of the pulley shows it much thinner.
3) No it is the Z coordinate of the grub screw.
4) The pulley relative to the axle.
5) The Y coordinate of the captive nut used on plastic pulleys.

Edited 2 time(s). Last edit at 06/01/2013 12:57PM by nophead.

---

[www.hydraraptor.blogspot.com]

Quote

nophead Wrote:
-------------------------------------------------------
> I didn't ask you about pulley_flange_thickness"
> ???? No !!!
>
> Yes you did
>
>

No I didn't when you look at my post #11

Is pulley_hub_dia 12,2mm ?

Is pulley_hub_length 7.5mm ?

Is pulley_flange_dia 16mm ?

pulley_screw_z : is z corresponding to screw length ?

pulley_offset : what is the this "offset" between what and what ?

pulley_nut_y : what is nut_y meaning ?

Quote

> 1) No pulley_hub_dia is the diameter of the hub,
> which is 16mm on that page.
> 2) It is on the diagram but the picture of the
> pulley shows it much thinner.
> 3) No it is the Z coordinate of the grub screw.
> 4) The pulley relative to the axle.
> 5) The Y coordinate of the captive nut used on
> plastic pulleys.

About your answer to question 2, I am looking at the diagram.

I didn't order my pulley here , so I don't care about the picture....

What was important is the diagram ,and the numbers , to help me understand your scad file description about the pulley

Thanks so much for taking finally a little time to answer my questions.

I hope you had time to eat before answering me !

Best regards Mr Nophead

Edited 1 time(s). Last edit at 06/01/2013 01:02PM by koumac.

koumac: English is not your first language, so it may help you to know that your tone is coming across as very rude. Given that you have not purchased one of his kits, he has no obligation to help you, but is doing so out of kindness. Therefore, politeness is appropriate, rather than a sense of entitlement.

Gerv

This might help some people, GT2 belts seem quite popular.
I'm not 100% sure about
function pulley_offset(type) = type[12];

I haven't shown the below in the drawing, I understand they locate the grub screw. (possibly from the axis of the shaft to the base/centre of the grubscrew?)
function pulley_screw_length(type) = type[10];
function pulley_screw_z(type) = type[11];
function pulley_nut_y(type) = type[13]; - "The Y coordinate of the captive nut used on plastic pulleys"

Happy to update the drawing if it's useful to the community


Edited 2 time(s). Last edit at 06/03/2013 05:52PM by isolt.

Hello Isolt,

Thanks a lot for your drawing and positive contribution.
I have the same question than you about the real meaning of "pulley_offset"

Your drawing iv very nice and will help others

Regards,
JC

Pulley offset is a vector used to place the pulley at the right place on the motor shafts.

---

[www.hydraraptor.blogspot.com]

Quote

nophead Wrote:
-------------------------------------------------------
> Pulley offset is a vector used to place the pulley
> at the right place on the motor shafts.

So for T2.5 pulley, pulley_offset is a vector equal to [0, 0,1.3]
function pulley_offset(type) = type[12]

For GT2 pulley shoud we keep the same vector value of [0, 0,1.3] ???

Thx

It probably needs a slightly different value to line up with the belt. It doesn't affect anything other than where the pulley appears in the model. I think the only value that affects the plastic parts is the inner radius together with the belt dimensions.

---

[www.hydraraptor.blogspot.com]

Was a GT2 version of the Mendel90 ever built? I am curious as to the status of this project.

Nophead, out of curiosity why did you choose to go with T2.5 belts over GT2 belts given the information shown here:
[reprap.org]

Your printers are clearly very high quality, so I'm wondering if maybe the belts don't matter so much, or maybe we can improve the design even more by going with GT2.

Thanks for contributing the Mendel90 design to the community!!

I'm currently sourcing parts for a M90 Sturdy using GT2 belts (I'm not expecting my M90 to outperform all the non-GT2 M90's out there though ), as far as I can see the definitions for GT2 are now included in the scad files, so I assume Chris updated them since this thread was started.

If you look in belts.scad you can see these types defined:

T5x6 = [ 5, 6, 2.25];
T5x10 = [ 5, 10, 2.25];
T2p5x6 =[2.5, 6, 1.7];
GT2 = [2.0, 6, 1.38];

So I just set my X and Y belt types to GT2 in sturdy_config.scad before running make_machine.py


EDIT:
If you take a look at that link you provided, you will see this sentence:

"Actually there are doubts about claim that T5 / T2.5 is causing backlash."

I think the link there explains Nopheads position on T2.5 belts.

Edited 1 time(s). Last edit at 01/02/2015 07:05PM by plankton.