Replacement Encoder Disc?

[Jeshua]

Greetings,

I made a huge bonehead mistake and bent my rotary encoder - destroying it. It is a really nice 800/oz servo I got from eBay. I have a picture of the encoder at: http://3dtopo.com/Encoder.jpg

I am afraid it has no brand name on it. I believe it is a 500 line encoder. When I do a google search for encoders, I get tons of stuff I have to wade through - does not look like it will be easy to find a replacement. When I look on eBay I can't find any just discs for sale.

I am guessing it is about a $20 part. The alternative is I would have to buy a new $300 servo.

I am hoping someone might be able to recommend a good place to look.

Thank you!

[TOTALLYRC]

Originally Posted by Jeshua Greetings, I made a huge bonehead mistake and bent my rotary encoder - destroying it. It is a really nice 800/oz servo I got from eBay. I have a picture of the encoder at: http://3dtopo.com/Encoder.jpg I am afraid it has no brand name on it. I believe it is a 500 line encoder. When I do a google search for encoders, I get tons of stuff I have to wade through - does not look like it will be easy to find a replacement. When I look on eBay I can't find any just discs for sale. I am guessing it is about a $20 part. The alternative is I would have to buy a new $300 servo. I am hoping someone might be able to recommend a good place to look. Thank you!

I can see the letters HP in the photo. It looks like it was is a HEDS series encoder.
You can contact US Digital, they should be able to sell you just the disc based on the ID and OD of the part.
If you take the encoder off and flip it over, there is a good chance the it has a number such as 500 on the bottom side.

You could also get a amt-102 encoder that is capacitive vs optical, has adjustable resolution and is about the same price as the disc you need.

http://www.amtencoder.com/

They are available from Digi-key. I was given great service when I purchased mine and it is running really nice on my milling machine. When I get the time I will swap the other 2.

[Jeshua]

Thanks TOTALLYRC!

I flipped over the encoder and there are some numbers on it:

http://3dtopo.com/Encoder2.jpg

It is 25mm OD and 6mm ID. It has a clip I am not sure how to get off though.

That encoder you have sounds pretty nice. I am just hoping to get it up and running with a minimal number of modifications at this point.

I don't even have my mill finished yet, so its a bit early for upgrades!

[Jeshua]

Thanks again!

I think I just found the animal:

http://usdigital.com/products/E2/?source=motionnet

Do you know if I would get better accuracy with higher resolution? I think mine is 500, but they go up to 1024. Or should I just stick with what was on the servo?

Looks like I made a spendy mistake! But not as bad as having to buy a new servo.

[TOTALLYRC]

Higher resolution is great if you can deliver pulses fast enough.
If using a PC and Gecko G320's for instance, 500 is about right unless you have some really weird screw pitch.
On my Mach3 DSPMC/ip powered mill I can handle 2 MHz encoder pulses, as opposed to Mach3 through the p-port which can only output pulses/steps at 100 kHz max.

Mistakes are the price of being human, if you learn from them they are cheap education, in most cases.

[Al_The_Man]

Depending on the diameter of the the shaft, you may be able to use one of the NOS encoders Renco are dumping on ebay right now for $20.00.
They also have nice ball bearing models for $70.00.
If this is a DC servo you do not need to use the commutation pulses that come with some models.
Al.

[Jeshua]

Originally Posted by TOTALLYRC Higher resolution is great if you can deliver pulses fast enough. If using a PC and Gecko G320's for instance, 500 is about right unless you have some really weird screw pitch. On my Mach3 DSPMC/ip powered mill I can handle 2 MHz encoder pulses, as opposed to Mach3 through the p-port which can only output pulses/steps at 100 kHz max. Mistakes are the price of being human, if you learn from them they are cheap education, in most cases.

Thanks TOTALLYRC!

Yes, I am using Gecko 320's and a older PC. I am using a timing belt drive with a 4:1 ratio (4 servo turns per pulley revolution)...

[TOTALLYRC]

Originally Posted by Al_The_Man Depending on the diameter of the the shaft, you may be able to use one of the NOS encoders Renco are dumping on ebay right now for $20.00. They also have nice ball bearing models for $70.00. If this is a DC servo you do not need to use the commutation pulses that come with some models. Al.

I completely forgot, I am using these on my mill and they are a great bargain if the shaft size is what you need. They are .250" id.
I am only upgrading to the amt-102 for the greater resolution.

Originally Posted by Jeshua Thanks TOTALLYRC! Yes, I am using Gecko 320's and a older PC. I am using a timing belt drive with a 4:1 ratio (4 servo turns per pulley revolution)...

What is the lead screw pitch or its tpi?
Out of curiosity, what are you building?

Mike

[Jeshua]

Originally Posted by TOTALLYRC What is the lead screw pitch or its tpi? Out of curiosity, what are you building?

Hi Mike,

I just saw this post! Sorry for the delay!

I am build a 5'x5'x2.5' milling machine. It has a usable area of 4'x4'x2'.

Here are some pics of it:

http://OpenOSX.com/CNC-11.9.09/

-jeshua

[TOTALLYRC]

Looking good.

Mike

[Stewey]

Our internet is very slow, and those links you posted (US Digital) and the photo are taking forever to come up, so I'll reply here without waiting any longer.

If it's a HEDS encoder, well I've just replaced an HEDS 5500-A06 encoder, which was about $66 Australian. Fortunately the new one came with the very needed 0.8mm allen/hex key used to remove the encoder disc from the servo shaft.

The encoder is a complete unit, with a snap-on cover. There's a twist/cam to help align the disc in the right place, and a tiny blue hole through which the allen key fits to tighten the disc to the shaft.

The 5500-A06 numbers all mean something.
The A means it's a 500 CPR count.
The 06 = 1/4" diam shaft
the two zeros means it's a 2-channel counter- just A & B- and it's blocked, not a through shaft encoder.
the first 5 doesn't mean anything I could fathom, but the second means it's a standard mount.

Agilent made them, and other companies make clones also.
The S at the end of the HEDS means the counter disc is steel, as opposed to film, which has an M instead of an S (i.e. HEDM....)

Hope that helps!

[Jeshua]

Hi,

I should have checked before I bought this encoder, but will a A & B low (A- & B-) work with the Gecko 320? I ended up getting this encoder:

Renco Encoder

It has an Open Collector output type.

Also, I am not sure what this means: "RCML15 Series combines brushless motor commutation pulses and incremental position feedback in a low profile optical encoder". Does that mean I have to have a brushless motor to use it?

This is the motor I got:

Servo Motor

Sorry, but all of this stuff is really confusing to a noob! I looked at the Gecko 320 manual and it basically just says it has to be a "quadrature TTL output type"...

Thanks!