Encoder Basics

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BigWillieStyle
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Re: Encoder Basics

Post by BigWillieStyle »

Question

Lead, Pitch, TPI all refer to different things but numerically are all equivalent?

*Note in below example TPI is actually 5.08 according to my arithmetic.

5mm Lead = 5mm Pitch = 5 TPI*

Is this correct?
frijoli
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Re: Encoder Basics

Post by frijoli »

woffler wrote: Tue Jan 02, 2018 2:11 pm Hi all ,i have a 16 bit encoder differential driver receiver it says on my servo motor for my spindle ,with A+A-,B+B-,Z+Z- it is a 1.8kw servo motor from DMM tech that i use on my lathe .
I was wondering if it would interface with the Acorn board ?
The DMM servo encoder out will work with Acorn.

Clay
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woffler
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Re: Encoder Basics

Post by woffler »

Thanks for the reply Clay
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Re: Encoder Basics

Post by tblough »

BigWillieStyle wrote: Fri Jan 05, 2018 1:03 am Question

Lead, Pitch, TPI all refer to different things but numerically are all equivalent?

*Note in below example TPI is actually 5.08 according to my arithmetic.

5mm Lead = 5mm Pitch = 5 TPI*

Is this correct?
BigWillie, lead and pitch are the same. TPI is not - it is the inverse of the others. A 0.2" pitch is 1/0.2 = 5 TPI.

Pitch is how far a screw advances in one turn. TPI is turns per inch. So if one turn moves 0.2 inches then 5 turns move one inch. Metric screws are normally specified based on pitches. Imperial screws are classified on turns per inch.

Your example gives the false impression they are equivalent only because 5mm is close to 0.2" but not exactly. 5/25.4 = 0.19685“. 1/0.19685 = 5.08 turns per inch.
Cheers,

Tom
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Re: Encoder Basics

Post by DICKEYBIRD »

woffler wrote: Tue Jan 02, 2018 2:11 pm Hi all ,i have a 16 bit encoder differential driver receiver it says on my servo motor for my spindle ,with A+A-,B+B-,Z+Z- it is a 1.8kw servo motor from DMM tech that i use on my lathe .
I was wondering if it would interface with the Acorn board ?
Remember that the servo motor must drive your spindle at a 1:1 ratio...no belt reduction.
Milton in Collierville, TN

"Accuracy is the sum total of your compensating mistakes."
cncsnw
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Re: Encoder Basics

Post by cncsnw »

tblough wrote:lead and pitch are the same. ...
Pitch is how far a screw advances in one turn.
Just to be pedantic here:
- Lead is how far a screw advances in one turn.
- Pitch is the distance between successive thread crests.
- They are the same for a single-start thread (the vast majority of threads you will encounter).
- They are different for multi-start threads: lead = pitch * number of starts.
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Re: Encoder Basics

Post by BigWillieStyle »

Thanks tb, I appreciate the clarification. Also with regard to encoders, through some additional reading I found a diagram via Dynapar as being a helpful tool for those less familiar, like myself, to delineate the semantics of encoder classification.

http://www.dynapar.com/uploadedFiles/_S ... _29_13.pdf

Image

To the experts, please confirm or correct my assertation with regard to the correct encoder type.
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Re: Encoder Basics

Post by Chaz »

Is there any way to use an encoder that does not make the individual A- B- and Z- available but uses a common instead?

This is the specsheet.

https://docs-emea.rs-online.com/webdocs ... e8dd0d.pdf

Thanks
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Re: Encoder Basics

Post by Chaz »

Probably doesnt matter, it has too low res anyways to be any good it seems.
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Re: Encoder Basics

Post by jmaks »

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