Like many of you, I earn my living working with CNC machines (mostly routers). We have a variety of routers, most of which run on Shopbot hardware and software. Earlier this year, our very large (5'x20') 2001 Shopbot PRT began to fail wildly. Sometimes an axis would stop moving or even go in the opposite direction. Sometimes there were communication errors. After trying to diagnose them without success, it was time for a better solution.
Here is the original V4G Shopbot control box. As you can see, it was enclosed in an ATX case, used a 63v torroidal power supply and a large breakout board for its Gecko 203V drivers. The drivers were oriented vertically and without heatsinks. An ATX power supply provided 5v and 12v power to the board. I decided to strip whatever components I thought were useful from the existing control box. Mainly, the power supply and drives. I ravaged an old Denford control box as well for bits and pieces. I made quite a mess. After a bit of cleaning up, things were starting to take shape And eventually, this was built: The PRT was never made to be incredibly rigid or move/jog/cut at fast speeds. That wasn't what we needed anyway. We needed our machine to handle very large files and cut for hours reliably. This Shopbot PRT, with the addition of the Acorn now runs better than it has ever had. It is rock solid and can run all day in and out without a hiccup. We're even running it on a PC that doesn't meet the full recommended specs! I'd like to mention also that Shopbot uses a MODBUS method of communicating with VFDs. Unfortunately, they really only support one model (Yaskawa) VFD and you can't change any MODBUS parameters. So if you had another brand, you were stuck without any sort of software speed control. Connecting the VFD to the Acorn for spindle on/off and speed control using the analog 0-10v and output relay was rather straightforward and added a capability that we didn't have previously. Thanks to Toaster (Eric) for reminding me to actually set Output 1 to spindleFWD.
![Smile :)](./images/smilies/icon_e_smile.gif)
![Smile :)](./images/smilies/icon_e_smile.gif)
Thanks
Matt