Dynomotion

Group: DynoMotion Message: 7437 From: tig415 Date: 5/6/2013
Subject: Spindle encoder for rigid tapping
I'm setting up my mill for rigid tapping. I'm working out the encoder for the spindle. I'm running it with a timing belt and pulley arrangement. My max spindle speed is 7000 RPM.

My question is are there any considerations to how fast I should drive the encoder? 1:1 or would I be better off reducing the speed of the encoder with the pulleys?

I don't plan on tapping at 7000 rpm but it would be nice if the encoder was accurate at that speed :)
The encoder I'm using is the AMT-102.

http://www.cnc4pc.com/Store/osc/product_info.php?cPath=64_78&products_id=363

Thanks
Derek
Group: DynoMotion Message: 7438 From: Tom Kerekes Date: 5/6/2013
Subject: Re: Spindle encoder for rigid tapping

Hi Derek,

The scaling doesn't necessarily need to be 1:1.  Other ratios would just be like having a different number of counts/rev on the encoder.

KFLOP Encoder inputs are limited to 1MHz post-quadrature counts per second. 

7000 RPM with 1:1 ratio at 1024 pre-quadrature ppr would be:

7000 /60 x 1024 x 4 = 478KHz

I don't particularly like capacitive encoders like those but it should work.  It appears they only have single ended outputs.

Regards
TK

Group: DynoMotion Message: 7439 From: tig415 Date: 5/6/2013
Subject: Re: Spindle encoder for rigid tapping
Thanks Tom

I have a few US digital differentials around as well so I'll use one of them. What would be the minimum wheel count before quad you would recommend. I think 500 is as high as I go.

I can order a new disk but If I can use what I have it would be better.

Derek


--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
>
>
> Hi Derek,
>
> The scaling doesn't necessarily need to be 1:1.  Other ratios would just be like having a different number of counts/rev on the encoder.
>
> KFLOP Encoder inputs are limited to 1MHz post-quadrature counts per second. 
>
>
> 7000 RPM with 1:1 ratio at 1024 pre-quadrature ppr would be:
>
> 7000 /60 x 1024 x 4 = 478KHz
>
> I don't particularly like capacitive encoders like those but it should work.  It appears they only have single ended outputs.
>
> Regards
> TK
>
>
>
> ________________________________
> From: tig415 <tig416@...>
> To: DynoMotion@yahoogroups.com
> Sent: Monday, May 6, 2013 10:19 AM
> Subject: [DynoMotion] Spindle encoder for rigid tapping
>
>
>
>  
> I'm setting up my mill for rigid tapping. I'm working out the encoder for the spindle. I'm running it with a timing belt and pulley arrangement. My max spindle speed is 7000 RPM.
>
> My question is are there any considerations to how fast I should drive the encoder? 1:1 or would I be better off reducing the speed of the encoder with the pulleys?
>
> I don't plan on tapping at 7000 rpm but it would be nice if the encoder was accurate at that speed :)
> The encoder I'm using is the AMT-102.
>
> http://www.cnc4pc.com/Store/osc/product_info.php?cPath=64_78&products_id=363
>
> Thanks
> Derek
>
Group: DynoMotion Message: 7440 From: Tom Kerekes Date: 5/6/2013
Subject: Re: Spindle encoder for rigid tapping
Hi Derek,

I think 500 ppr (2000 quadrature counts/rev) should work.

Regards
TK