On 13/06/2020 15:49, Gene Heskett wrote:
On Saturday 13 June 2020 09:29:47 Lester Caine wrote:
It seems I have a set of GYS701DC2 and mating servo drivers sitting in
a big metal box with a laser sitting in the top of it. I think it's
due for stripping down so I can salvage all the usable bits, but I've
hit a bit of a brick wall I can't find any data on the motors such as
what encoder they are fitted with. Anybody got an old manual as google
is proving lacking.
While trawling around I cam across the JMC iHSV57-30-18-36 which looks
like a possible contender if I was starting from scratch. However once
again it does not list the resolution of the encoder, playing instead
on it's 'stepper motor' like setting. I've established that the built
in driver can handle any encoder from 1 to 2500 lines and it even
lists 1000, 1250 and 2500 as the 'standard' encoder resolutions, but
not how to recognise just which one is fitted :( In my book, the 2500
line encoder gives a native 10000 step resolution without any
'micro-stepping' and when combined with a 3mm pitch ball-screw ( on
the Taig mill ) looks like a magic combination.
Anybody using the iHSV57-30-18-36 and worked out what the native
resolution is? ... any feedback as to if it's even worth concidering?
Thats a problem I will face for the second time in a bit as I've bought a
pair of the 3NM stepperservo's myself.
These are equipt with 1000 line encoders, I think that are actually 250
line encoders. So for the lathe, I will have to plug in the sprocket
ratios and z screw stuff to get a usable z scale.
But I faced a similar problem with my g0704 when I put an encoder on the
top of the spindle motor because I had no clue what the gear ratio in
the head of the g0704 had it either gear. I intended to get, and have
but its failed at the moment, an index pulse from the spindle rotation.
So I cobbled up in the hal file, a counter which gave me the number of
pulses from the 1000 line on the motor, for 100 turns of the spindle,
measuring for both high and low gears, so I now have a couple switches
on the rim of the gearshift knob to tally which gear it is fully seated
into which in turn control a couple muxes so the tach and such stay
calibrated. By using a mux4 for the speed control I can also insert a
very low speed commend when its not quite seated in either gear. So I
can reach up and shift gears when its running and its turning very
slowly, the next gear flat faces mesh perfectly, and the selected speed
resumes when one of the tally's goes good.
That counter is still in the hal file, but commented out. and I just put
a copy in my web page for you, or anyone else, you can get it all from
my site in the sig, click on that and when you can see me & the missus,
add lathe-stf/ to the browsers address bar and ENTER. You should then
see another subdir named GO704-5i25-7i76/, click on that and help
yourself, that is a copy on the config dir for my GO704. The main
GO704-5i25-7i76.hal contains this counter. Copy it, fix the missing
addf's etc. I used halshow's command line to reset it for each run, and
a halmeter to read what it said. When reset, it counts indexes from the
third to the 103rd, for any axis you feed it from that has an encoder,
so divide what the halmeter says when it stops counting to get the
actual number of pulses for one turn, divide by 100.
I hope this is helpfull, Lester
I get exactly where you are coming from, but I think I've got a slightly
different take on things. I have found reference to the iHSV57-30-18-36
having a default of 4000 and that being '1:1' so this suggests the motor
has a 1000 line encoder ( 4000PPR ) but I would prefer even just the
1250 line encoder to restore some of the resolution lost moving from the
20TPI thread on the original leadscrew over the 3mm pitch of the ball
screw ... I suspect now that the 2500 line encoder may actually be too
high a frequency for the built in electronics which is a shame and
perhaps that is where we do need to use LinuxCNC to close the loop using
faster hardware than that built into the integrated servos?
I don't see the point of the 'serv ostepper' for anything other than the
raw steps of the motor itself? Although I suppose micro-stepping may be
more accurate if it's following the steps of the encoder?
Stay well and safe.
Cheers, Gene Heskett
--
Lester Caine - G8HFL
-----------------------------
Contact - https://lsces.uk/wiki/Contact
L.S.Caine Electronic Services - https://lsces.uk
Model Engineers Digital Workshop - https://medw.uk
Rainbow Digital Media - https://rainbowdigitalmedia.uk
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