Centroid Community CNC Support Forum

As the subject states, I am developing for the ShopBot commercial (or discriminating hobbyist) customer a turn key closed loop system to replace any and all systems made by SB on their PRT and PRS models. I am looking to see which options potential customers would like to see on these control systems.

General specs are 230vac-12 A. Up to 5 drives on 4 channels powered by 800va 75vac transformer. This puts dc volts in the drive a bit over 100 for max torque and speed. 10A capable drives with motor options up to ~1200ozin. System is a similar upgraded version of the Acorn Basic shown on page 2 here: viewtopic.php?f=62&t=2147&start=10

Pricing is currently ballparked at $2,495 for the 4 drive system. Motor, gearbox (belt reduction) cables (varies with length), and pinions would add to that price depending on actual products selected for the user. Based on testing, I am currently recommending a NEMA23 solution for all but those wishing to use the machine for commercial production. This would put a total cost for the system, which will outperform the OEM "alpha" up to 1000 in/min in the $4500 range including planetary gearboxes, adapter plates and pinion gears.

This system will deliver ~double the torque of the alpha in the cutting range and ~1 1/2 times the torque during rapids, has close to double the resolution and will propel a PRT faster than they should go, and a PRS 50% faster than the factory alpha settings. Faster, quieter and MUCH smoother cutting, what's to lose?

For those that might see themselves purchasing this system, which features would you like to see added, as standard or optional, above and beyond what is listed for the Acorn Basic system?

Torque vs Speed comparison between the proposed NEMA23 system with 5:1 gearboxes and their alpha system. Assume that their standard pulls less than half of the alpha in both torque and speed. Data is not shown above 1178 ipm as the ASM98AA-T7.2 is limited to that by the mfgr

As you said, what's to lose! And I'll add, as the numbers show, what's not to like!

Looking over the list on the linked page as to the options, I honestly can't think of anything more to add to the list except for maybe a bell and a whistle.

Oh, how about a way of playing SOUND7.WAV when a file starts! By the way, do you know where that sound came from?...Microsoft Windows 95 Space Cadet 3D Pinball!

Neither myself or the Centroid guys will help anyone looking to have a few seconds of woo-aah, woo-aah, woo-aah play before the machine starts. It's called cycle start, don't press it until you are ready!

.....

Now that some of these closed loop systems are off the bench, its time to post some pictures. A slightly upsized enclosure will allow accommodation of most any and all options, up to 5 drives on 4 axes, with 2 spindles or routers. As is standard with all the Acorn control systems, a user connection terminal block is provided.

Control shown below has 4 10 amp drives, with over a dozen motor options. Motor pictured is the one mentioned above with the speed/torque charts. For most all cases, this will be the recommended motor configuration, as it offers more torque than was ever put on a PRT or PRS model. Some production shops may wish to upgrade motors for higher duty cycle capabilities and this system will accommodate that option. Motor is shown mounted to a "PRS Adapter Plate". There is a separate design for the PRT model adapter plate that uses the original spring.

For more information email: GCnC411@gmail.com

new Shopbot CNC retrofit upgrade web page.
http://www.centroidcnc.com/shopbot_gcnc.html

Some comparison video of the conversion.


https://youtu.be/ZXWOoKvPytc

Adapters available for PRT models also

This controller is also available with NEMA34 motors, M12 connectors and 14 pin spindle interface to enable AVID customers to take advantage of the additional features of the Acorn controller and closed loop steppers.