Fanuc 3T pulse setting

[Nandop]

Hi all,
I have a Star Swiss lathe with Fanuc 3T.
Can i set/change by jumpers on the master board or the axis board, the encoders input resolution from 2500ppr to 2000ppr?
How i Do it?
Thanks.
Nandop

[f-bu]

If ballscrew pitch is 10mm, then I think it is not possible to use 2000 instead of 2500. See the description of DMR parameters, there is a table for different ball screw pitches and command increment.

[Al_The_Man]

The chart I have for the 3 shows for a 2000p/rev BS, the pitch required is either 1mm or 2mm or .1inch in imperial, using standard CMR/DMR values.
Although I believe that CMR/DMR can be changed from standard but maximum feedrate can be limited.
I have the calculation sheet from Fanuc but it is too large to post here.
Al.

[Nandop]

So, there is no way to use a 2000 ppr encoder in a 5mm pitch ball screw.
Because the Detect Unit is .0025 mm and isn´t 0.002 or 0.001
It´s that correct?.
Thanks for the answer.
nandop.

[Al_The_Man]

Not using the standard CMR/DMR, I believe it will allow different values but the Doc I included explains, I can send you the Fanuc DMR/CMR calculation sheet if you send an email ad by PM, it is too big to post here.
Al.

[Dan Fritz]

The jumpers on the main board to select 2000 or 2500 ppr are only for the F/V converter that generates the tach signal. The servo needs a 3v/1000 rpm tach signal, and the F/V converter needs the jumpers so it can generate that same tach signal with either a 2000 or 2500 ppr encoder. If your motors have tachs inside, then the F/V converter isn't used, and these jumpers do nothing at all.

If you want higher resolution for position detection, you may be able to double the CMR and the DMR but, like Al_the_man says, that would limit your feedrates also.

Generally speaking, a 2500 ppr encoder can only used when your ballscrew has a pitch evenly divisible by 5, like 5mm, 10mm, etc. All others use 2000 ppr encoders.