PR upgraded to 4G -- z unit value help?

[uffabrew]

I have an early 1990's PR ShopBot that we have upgraded to a 4G control board with the most current drivers (3.6.x) & firmware(1.4.0). It still uses the ball screw for the Z axis which is driven by a small motor. While the X & Y use a Shopbot upgraded rack and pinion system with larger motors.

The problem is that I can't figure out the Z unit value. The X and Y appear to be set correctly, but the Z is way off by at least three fold. Anyone have a similar setup that could post their Z value? I plan on calling Support on Monday, but prefer to get this solved sooner without the students hovering around.


Thanks,

Eddie Ufford
Hanford High School
Richland, WA

[rb99]

Hi Eddie,

I have a similar machine and I bought the 4g box but have not installed it yet. I know this does not help you, but I am very interested in how it works out for you....

I was going to post to see if anyone was using the ball screw with the 4G.

RIB

[jerry_stanek]

I have a PR with the 4g and it runs just sa good as my PRS standard. the value I use for my ball screw z is 10200 so that may get you started and adust from there.

[rb99]

Jerry does your z screw up? What speed is it set for move and jog?

What speeds do you use for x and y?

Thanks

RIB

[jerry_stanek]

yes my z is a screw drive and I use 1ips for move I cut sintra with a 1/4 inch bit at 4.5 ips with no problems. It will surface the table at 7ips if I jog faster than 8.5 ips it starts to stutter. normally I don't run this machine as the PRS has taken it's place but on some jobs where there is a lot of the same cuts I use it. That way I can be cutting while I am loading the other machine. There is a job pending final for 1800 cuts in 6 mil sintra that I hope to start this summer. 900 pieces of 4 X 8 sintra so Both machines will be used.

[rb99]

That is encouraging. Do you know how many teeth the pinion has? Which x & y motors you have?

Thanks,

RIB

[uffabrew]

The 10200 Z unit value setting worked and it appears to be extremely close if not dead on. I will do further testing later. My students are currently cutting out long-board skateboard decks. I have them use Parkworks to make ShopBot CNC file with tabs. So as long as the X & Y are dead on and the Z withing a 1/32" or less we can cut completely through blanks and into the sacrificial table.

The 4G upgrade has been vast improvement even with the old Z axis ball-screw. I kept my XY cutting speed is around 4.0 IPS while the jog speed is set to 6IPS. I haven't tested the top speed of the machine in a long time, as this seems to be a good speed for what we do. This might be slow to others, but with students using the Shopbot, it is better to have them cut slow and shallow than to break bits and ruin materials.

For my next upgrade we really need to replace the original X & Y utility struts and gantry system. But I will save that for summer time when no students are around and plenty of time to work on things.


Thank you very much Richard you saved me a lot of time and frustration plus my students can resuming using the ShopBot on Monday.

Best Regards

EAU

[rb99]

You are welcome, although it is Jerry that is the one who deserves the credit.

I am also wondering what size (or how old) a computer I can get away with?

RIB

[uffabrew]

MY PC is an old AMD single core CPU 3000MHz running XP. Only thing that bugs me about the control box to PC is the serial to usb converter. If it wasn't for that, I might attempt to run it on Windows 7 or even try Linux Mint. I was able to get Partworks to run in Linux Mint under the WINE program. I haven't tried to run the ShopBot on Win7 nor on Linux though.

I also teach a computer tech class so I am fortunate to have access to good hardware.

[jerry_stanek]

With the 4g you no longer have a serial to usb connection it is striaght usb. I have an old pentium 2 that will run my prs but I don't use it.