Just saw a linear motor XY table with linear encoders today...nice

[guru_florida]

Hi all,

For those that don't know a linear motor is not like a normal wire wound motor. It is a long flat magnet, usually rare earth magnet, and the moving part is a wound coil. If you've ever opened up a hard drive and seen the "voice coil" it is the same basic theory.

The linear encoder was a golden strip with vertical bars...but you couldnt see them, they were 20 microns apart and the whole golden strip looked solid. The guy said the encoders are big $$$.

The 20 micron spacing on the linear encoding strip was divided into a further 256 locations (the optical head doesnt read a perfect square signal, but an analog one, so it can subdivide).

The XY table was FAST!!! Almost appearing instant. Wish I had one.

C

[R3D3V1L]

Hi guru_florida

That golden strip you mention sounds like the RGS20-S tape scale from Renishaw. They are a well known British metrology company with a large US subsidiary near Chicago, Illinois and regional offices around the country. They offer high performance encoder systems at a competitive price and the support they provide customers is generally outstanding.

They would certainly be my first choice for an encoder system.

[guru_florida]

Originally Posted by R3D3V1L Hi guru_florida That golden strip you mention sounds like the RGS20-S tape scale from Renishaw. They are a well known British metrology company with a large US subsidiary near Chicago, Illinois and regional offices around the country. They offer high performance encoder systems at a competitive price and the support they provide customers is generally outstanding. They would certainly be my first choice for an encoder system.

Thats looks to be it...do you know what price range we are talking about for these things? The guy just said "expensive".

C

[R3D3V1L]

Hi guru_florida

Sorry for the late reply, a very long Christmas break!

I believe that the list price for the scale is approx £200 per metre, but with discounting for quantity I expect you could get it a lot cheaper.

Regards
R3D3V1L

[NEATman]

guru_florida

I used to work at a manufacturer that used large quantities of this Renishaw tape. It was about $5 per inch at discount.
Remember, that this tape takes on the thermal expansion rate of the material that you mount it on, (the reason for the tape and reccomended end clamps) so accuracy and repeatability are partly your responsibiility.

You may want to think about Heidenhain encoders, which have a metal gold tape as well, or thier glass scales. You may want to try RSF, as they have enclodes glass scales that are a bit less expensive than the others out there.

NEATman

[guru_florida]

Thats not a bad price, I could swing that. But what about the optical read head?

Thanks,
C

[daedalus]

hi, the rgh22 readheads are around £450 each, and the strip is £2.50/cm in small amounts. Thats from a quote for 0.5um encoders from last week.

I have a couple of assemblies with them in at work, but just be warned, they are a real PITA to configure with drives, as most are not designed to deal with encoder pulse rates that high.