Shopbot PRS 48x96 Acorn / Clearpath Conversion

All things related to the Centroid Acorn CNC Controller

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paulwall
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by paulwall »

Hey All - What Auto-tune torque did you guys start with for X tuning? I tuned Z with 100% torque and it was pretty violent. I'd like to dial it down for the gravity held axes.
paulwall
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by paulwall »

Alright, tuning is done. I ran the X at 100% torque without issue. And made a Y-axis config after turning the X-axis with 110lbs of added weight (half the weight of my gantry).

Now onto limit switches. I'm using the stock NPN proximity sensors from the ShopBot. It makes sense to me that these could be wired in series since they're NC circuits, by just feeding the blue wire into the black wire of the next NPN sensor. Is there a reason Centroid recommends wiring each NPN to it's own independent input?
Gary Campbell
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by Gary Campbell »

As a rule, inductance prox sensors do not perform well in series. Some better than others, you will have to test yours to be sure
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martyscncgarage
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by martyscncgarage »

paulwall wrote: Fri Jan 01, 2021 9:42 pm Alright, tuning is done. I ran the X at 100% torque without issue. And made a Y-axis config after turning the X-axis with 110lbs of added weight (half the weight of my gantry).

Now onto limit switches. I'm using the stock NPN proximity sensors from the ShopBot. It makes sense to me that these could be wired in series since they're NC circuits, by just feeding the blue wire into the black wire of the next NPN sensor. Is there a reason Centroid recommends wiring each NPN to it's own independent input?
You could run all of the proximity sensors to a opto isolated relay board and series the relay outputs. One end would to to COM and the other to your HOMEALL input.
KNACRO 4-Channel 10A Relay Module DC 24V with Optocoupler Isolation High Low Level Triger for Arduino
by KNACRO
Learn more:

I created a post in the Knowledge base forum on a great video from Automationdirect.com about proximity sensors and putting them in series.
viewtopic.php?f=63&t=5208
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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paulwall
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by paulwall »

The video is an excellent intro 101 to sensors, thank you Marty. And Gary I will test my sensors in series now before moving forward. I did have a question regarding the use of end-of-travel triggers. The ShopBots are setup this way in both X and Y travel.

Here's my question:
Image

Edit: Maybe the better question is, what happens when a home limit sensor (of any type) is triggered while running a program?
martyscncgarage
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by martyscncgarage »

paulwall wrote: Sat Jan 02, 2021 3:10 pm The video is an excellent intro 101 to sensors, thank you Marty. And Gary I will test my sensors in series now before moving forward. I did have a question regarding the use of end-of-travel triggers. The ShopBots are setup this way in both X and Y travel.

Here's my question:
Image

Edit: Maybe the better question is, what happens when a home limit sensor (of any type) is triggered while running a program?
If set as a home sensor or homeall nothing. Tripping a home sensor after the machine home does nothing. The control will ignore it unless you need to rehome.

If a sensor is in the middle of the travel, no big deal, you just use Positive and negative value distances from the sensor and tell the control which direction to FIND the sensor on power up. If you PARK the machine before you power down, the axis will be very close to the home sensors next time you power up.

IF you set a sensor input to Home/Limit it will trip....
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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Gary Campbell
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by Gary Campbell »

The SB control treats it's limit sensors in the most basic way. Virtually indescrete, even allowing motion past the sensor once hit.

I suggest that you remove the positive end triggers on X and Y, add one for the Z. Configure as home sensors and set your travel limits a fraction before the hard stops, you will not have any issues. Including decel to the limits even at full speed with the pendant
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paulwall
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by paulwall »

After a fair amount of trouble shooting, my machine is up and running enough to auto home. I'd like to find an auto home macro that approaches the limit switches at a quicker rate at first, then re-engages at a second slower pass to establish each axis home point.

But I'm very happy with the progress made. Turns out I was able to daisy chain my NPN proximity switches and a normal NC momentary switzh on the Z to get all the homing done on one input. I'm waiting for the slave Y proximity sensor in the mail for gantry squaring, but am getting closer to running my first chip cutting pass!

Sword
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by Sword »

Lookin' great Paul! Looks like a Kubota ShopBot. ;)

For a quicker approach rate, you need to up your "Slow Jog Rate" in the wizard (I'm using 250ipm) Also, utilize the "Park" function at the end of the day to pre-position the machine axes close to or at home, so it doesn't have to travel so far when homing.
From the manual...
13.23 M91 - Move to Minus Home
M91 moves to the minus home switch of the axis specified at the slow jog rate for that axis....
Also, if you want the final XY 0.00 position to be at the corner of your table, edit your cncm.hom file to do so with G91, using the actual distance from the prox to the table home. This can then be adjusted at any time for changes in your table home position.

Code: Select all

#105 = 3
M225 #105 "SET MACHINE HOME\nPress Cycle Start to continue\nPress Cycle Cancel to abort"

M92/Z L1         ; Move + to Z prox
M26/Z

M91/X L1         ; Move - to X prox
G91 G0 X3.3988   ; Move X required distance from prox to table X home

M91/Y L1         ; Move - to Y prox
G91 G0 Y1.9231   ; Move Y required distance from prox to table Y home

M26/X/Y          ; Set Machine home at current location
G90              ; Return to absolute positioning
M225 #105 "** Machine home set, have a G90 great day! **"
Last edited by Sword on Mon Jan 11, 2021 12:30 pm, edited 1 time in total.
martyscncgarage
Posts: 7138
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Re: Shopbot PRS 48x96 Acorn / Clearpath Conversion

Post by martyscncgarage »

250ipm seems fast to home....
Also, use the Park function when shutting down at the end of the day. Also you can manually jog the machine closer to the switches BEFORE homing the machine if you forget to Park it
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
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