Lathe Spindle encoder with cheap (max. 50$) LPT Breakeout board

You are right and i was thinking the same to reduce it in the .ini. Still. thanks for taht Andy.

Now i am still wondering how the calculation of the spindle encoder sampling rate works. Could you help me out with that. Even is someone would say (as PCW think i did ont he example with my latency of 5000-7000) that i should have an sampling rate of 50-60 Khz, i would still like to understand that, just to learn it

Thanks in advance.

denhen89 wrote: Now i am still wondering how the calculation of the spindle encoder sampling rate works.

You already did the calculation, you just chose not to believe the answer.

1000000000 / 31250 = 32kHz

If you use a 10,000 base thread then you get 100kHz

Thank you very much !
Now i know that i can also try it with an cheaper board, because it should theoretically work pretty good with the spindle "software encoder".

Andy, it would be great if you could answer me 2 questions:
1. I saw on your youtube videos that you are using 2 mpg handwheels on your lathe. Do you use them much? If so, more just for positioning or also for cutting ?
2. If i would also want to add 2 mpgs, how does it then work with the encoder sampling rate? 100 KHz no mater how many software encoder i use or does the sampling rate gets lower the more software encoder i use?

Thanks in advance!

denhen89 wrote: 1. I saw on your youtube videos that you are using 2 mpg handwheels on your lathe. Do you use them much? If so, more just for positioning or also for cutting ?

I actually have 4 mpgs on the lathe, one for feed override, one for spindle override and the X and Z ones on the saddle.

I use them a lot. Both for positioning before starting a cycle and for touching-off, and also for some machining (mainly for parting rather than other ops)

2. If i would also want to add 2 mpgs, how does it then work with the encoder sampling rate? 100 KHz no mater how many software encoder i use or does the sampling rate gets lower the more software encoder i use?

Every encoder is sampled every rev, so they all work at the same speed irrespective of how many there are.

Though I should point out that my lathe has a big collection of Mesa cards. There is even a 7i73 in the saddle just to handle the MPGs and the limit switches (so that the only wire from the saddle to the main controller is a single CAT5)

Oh yes i remember, there was 4 handwheels on your lathe!

Hm, so maybe i will when everything is working well also install at least 2 mpgs.
But now i have to ask again just to make sure i understand it correctly: Even i will use a software encoder, i could also use the mpg handwheels and with the "very good" latency i have and the good encoder sampling rate, the mpg handwheels will work fine, no matter how many i would have installed? I am also asking because someone from youtube told me they might not work properly if i will turn them quickly, like that some steps could be missed.

You very eperienced with cnc/linuxcnc and all those things, so for sure you have good reasons to use that kind of setup, but i am trying to safe a bit money, because i just finnished the cnc router and due to the much fun i have doing those things i also started the Lathe project. So, spending a lot of money in the best hardware doesnt make any sense as long as i dont make any money with it, but of course i still want to build an nice lathe

denhen89 wrote: But now i have to ask again just to make sure i understand it correctly: Even i will use a software encoder, i could also use the mpg handwheels and with the "very good" latency i have and the good encoder sampling rate, the mpg handwheels will work fine, no matter how many i would have installed?

Yes. All the input pins are read at the same time regardless of how many are actually active / used.[/quote]

but of course i still want to build an nice lathe

You mentioned linear slides. I am not sure that's a good idea. I think most CNC lathes still use normal ways. I think they are stiffer.