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BOM issue with Y toothed pulley

RoundSparrow

BOM issue with Y toothed pulley
December 17, 2007 06:50PM

Registered: 16 years ago
Posts: 182

So the BOM specifies a McMaster-Carr part that has a 1/4" bore... yet it is supposed to go on a M8 metric rod? It doesn't fit.

it DOES fit the shaft on the motors... but the Y pulley goes on a M8 rod that is coupled to the motor... or am I confused?

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Ian Adkins

Re: BOM issue with Y toothed pulley
December 18, 2007 03:30AM

Registered: 16 years ago
Posts: 270

In all my searching i could not find a 2.5mm pitch pulley with a 8

Ian
[www.bitsfrombytes.com]

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ZachHoeken

Re: BOM issue with Y toothed pulley
December 18, 2007 10:35AM

Admin
Registered: 17 years ago
Posts: 1,487

correct.

the idea is that you buy the 1/4" bore and drill it out to 5/16 (or 8mm if you have the bit)

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RoundSparrow

Re: BOM issue with Y toothed pulley
December 18, 2007 11:58PM

Registered: 16 years ago
Posts: 182

I did drill two out with drill press, and results were not very good. Inner insert turns.

I'm thinking of just using a 1/4 inch rod in place of the reprap 8mm rod.

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Ronson

Another Question with X/Y toothed pulleys
August 04, 2008 05:50AM

What is the diameter of the toothed pulleys, I build them by casting Epoxyd and my selfmade mould. On the reprap-internetpage i couldnt find a declaration about that.

I think its important or is the software scaleable?

from Germany MFG - i like that Project

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sid

Re: BOM issue with Y toothed pulley
August 04, 2008 08:13AM

Registered: 17 years ago
Posts: 550

Egal, as long as they are all the same winking smiley

don't make them too small though, to have enough teeth holding the belt.

'sid

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Ronson

Re: BOM issue with Y toothed pulley
August 04, 2008 02:54PM

I can

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nophead

Re: BOM issue with Y toothed pulley
August 04, 2008 03:31PM

Admin
Registered: 17 years ago
Posts: 7,879

The host software has preferences where you can enter the steps per millimeter for each axis. A bigger radius will just give you lower resolution though.

[www.hydraraptor.blogspot.com]

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nophead

Re: BOM issue with Y toothed pulley
August 04, 2008 03:47PM

Admin
Registered: 17 years ago
Posts: 7,879

To get 0.1mm steps on the X and Y axes you need a mold with an outside diameter of 14mm lined with a piece of belt that has 16 teeth.

The pitch of the belt is 2.5mm so one rev is 16 * 2.5 = 40mm. With a 400 step motor or a 200 step motor half stepped you get 400 steps per rev so 0.1mm per step.

[www.hydraraptor.blogspot.com]

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sid

Re: BOM issue with Y toothed pulley
August 04, 2008 07:15PM

Registered: 17 years ago
Posts: 550

or to be precise, you can measure the pulleys in the stl file.

That way you'll have exactly the size that was uploaded to the set.

Or if you do what nophead tells you to, you're definately on the right path winking smiley

'sid

Edited 1 time(s). Last edit at 08/04/2008 07:19PM by sid.

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nophead

Re: BOM issue with Y toothed pulley
August 05, 2008 04:45AM

Admin
Registered: 17 years ago
Posts: 7,879

I tried making one from the STL file and it only had 13 teeth and was very thin walled, so I gave up on that, bought metal ones and bored out the hole with a lathe.

I don't know why the official design has 13 tooth pulleys (I will ask) but 16 seems to work fine, gives a round number for the outside diameter and the steps per mm.