Retrofitting a 1987 maho mh600c

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18 Jan 2019 19:00 #124411 by Mccartymachine1
I am in the process of retrofitting my recently purchased maho MH 600c. I hope this is the correct spot to post this. First question is how can I switch the software between a vertical spindle and horizontal? I have been working on my configuration so far as if it is only horizontal. I will be posting more info, picture and questions. I have purchased a mesa 5i25, 7i77 p&g kit. Machine only has 83hrs on it!

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20 Jan 2019 12:23 #124476 by BigJohnT
Just create two configurations, one for vertical and one for horizontal if the hardware is different.

JT

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21 Jan 2019 13:44 #124532 by andypugh

Just create two configurations, one for vertical and one for horizontal if the hardware is different.


This is the approach I take with my Universal milling machine.

As CAM-created G-code always has the Z axis parallel with the spindle, but the horizontal spindle is parallel with what is normally the Y axis I have two different configs (Two INI files in the same folder) so that the configs share tool table and several HAL files, but in one config the XYZ axes are switched about.

I actually have three configs, one is set up as a dedicated gear hobber.

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22 Jan 2019 23:54 #124640 by Mccartymachine1
Thank you. That makes sense. I was thinking it had to be something that I could switch while linuxcnc was running.
The next question I have is about linear scales. I have purchased two of the three scales already and I hope I haven't made a mistake. I got Chinese 1um sino brand ka300 scales. Would 5um have been ok? Will the 1um scales limit my rapid moves? Any chance these scales will last? I have the x scale wired in but not mounted yet. It seems to read ok but I can move it fast by hand and it looses position (might be my mesa card settings). I will be starting to tune the servo once I have it mounted.

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23 Jan 2019 11:16 - 23 Jan 2019 11:20 #124656 by andypugh

The next question I have is about linear scales. I have purchased two of the three scales already and I hope I haven't made a mistake. I got Chinese 1um sino brand ka300 scales. Would 5um have been ok? Will the 1um scales limit my rapid moves? .


What are you counting with? What rapid speed do you require? What is the data output format?

The 7I77 uses multiplexed encoder signals to save interface pins. The multiplexing
rate will determine the maximum encoder count rate. Default multiplexing rate with
HostMot2 firmware is ClockLow / 8,or approximately 4 MHz with 5I25 or 6I25 FPGA host
interface cards, giving a resolvable count rate of 2 MHz. The Multiplexing rate can be
increased if desired but high multiplex rates will require short cables between the FPGA
controller card and the 7I77 due to signal integrity and time-of-flight considerations.
Maximum practical multiplex rate is approximately 12 MHz (and 6 MHz count rates)


So, 2MHz count rate and 1um resolution means a max speed of 2m/S. That's fairly fast, I would have thought faster than your Maho.
Last edit: 23 Jan 2019 11:20 by andypugh.

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23 Jan 2019 22:46 #124691 by Mccartymachine1
It may be perfectly fine. I had only tested it with the encoder in my hands. Just got the way wipers replaced and now waiting on metal stock for brackets to mount the scale. Not much space on the x axis for it but just barely will work. Sino brand scale seems to be ok quality. Cost was $140 us dollars for 720mm travel 1um. If it's repeatable and lasts I'll be thrilled. The good scales are way out of my hobby budget.

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24 Jan 2019 03:18 #124708 by Mccartymachine1
I am getting a bit overwhelmed while starting to read about PID tuning. Is there a simple step by step one could point me to? I am finding lots of info but it's either very specific or just the theory behind it. I have all servos running well in open loop.

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24 Jan 2019 13:41 #124736 by andypugh

I am getting a bit overwhelmed while starting to read about PID tuning. Is there a simple step by step one could point me to?


Try: gnipsel.com/linuxcnc/tuning/index.html

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24 Jan 2019 16:13 #124743 by Mccartymachine1
Thank you. That one looks fairly straightforward and easy. The only thing I'm unsure of is the line about setting the velocity in machine units per second. I am using inches and it is a velocity drive.

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25 Jan 2019 12:56 #124806 by andypugh

Thank you. That one looks fairly straightforward and easy. The only thing I'm unsure of is the line about setting the velocity in machine units per second. I am using inches and it is a velocity drive.


Then machine units are inches and units per second is units per minute / 60.
(Just in case you thought it was in some way more complicated than it appears)

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