Centroid Community CNC Support Forum

I just purchased a Centroid Acorn, DMM AC Servo, a bunch of stuff from Automation Direct and thishttps://www.ebay.com/itm/HP-EliteDesk-8 ... 4#viTabs_0 computer - any concerns? It would seem to meet the minimum requirements as I understood them.
I am looking to source a couple items Pulleys and Wire troughs - any suggested sources?

I don't see anywhere in the ad the actual processor info. You need the specific processor info, not just i5 and 2.9GHz.
What you want to see is Intel Core i5-XXXX @2.90GHZ. Where XXXX is the specific info you need. Without this info there's no telling if it meets the minimum for Acorn. Then search that info on this site:

https://www.cpubenchmark.net/

I believe the number is Intel Core i5-4570 CPU @ 3.20GHz

In the item specifics it says it's a 2.90 GHZ but you can verify with the seller.

Searching the i5-4570 CPU, it has a single thread rating of 2024 so that will meet the minimums for Acorn.

Thanks Shawn appreciate your contribution to future success!

I'm reviewing the doc for Acorn connections and am wondering about the P10 connection from Spindle encoder. If I add an encoder to the spindle this is what enables rigid tapping?
Currently I have a Unidrive VFD running open loop and have an encoder I will add to be able to run closed loop vector - I currently don't have any torque at speeds below 500 rpm so this update will be welcomed.

The spindle encoder on the Acorn is what enables rigid taping. It DOES NOT close close the loop with the VFD. If you have an encoder connected, Acorn will display the exact rpm the spindle is running, but it will not adjust the analog output to make the actual speed = programmed speed.

If your VFD supports closed loop operation with an encoder, you will need a separate encoder for the VFD. Sensorless Vector Control on the VFD will fix the low-end torque problem without having to add an encoder.

tblough wrote: ↑Wed Apr 21, 2021 2:20 pm The spindle encoder on the Acorn is what enables rigid taping. It DOES NOT close close the loop with the VFD. If you have an encoder connected, Acorn will display the exact rpm the spindle is running, but it will not adjust the analog output to make the actual speed = programmed speed.

If your VFD supports closed loop operation with an encoder, you will need a separate encoder for the VFD. Sensorless Vector Control on the VFD will fix the low-end torque problem without having to add an encoder.

What I think you're saying is I need two encoders; one on the Motor and one on the spindle. The current setup has the motor changing speed based on the 0-10V from the existing breakout board - there is no encoder. The encoder I'm planning on adding will go to the VFD and to get rigid tapping I would need another on the spindle and connect it to the Acorn.
I'm not sure "sensorless Vector Control" is an option for my Unidrive...SPmodel 2203. I'm hoping a future update will include a VFD using single phase power

You only need two encoders if your VFD supports an encoder input and you want to enable it for some reason. It is not necessary nor particularly useful. I put it out there because you mentioned:

Currently I have a Unidrive VFD running open loop and have an encoder I will add to be able to run closed loop vector

If you do that, unless your drive has an encoder passthrough AND you have belted the motor to the spindle with a 1:1 TIMING belt, you will need another encoder on the spindle connected to the Acorn for rigid tapping.

Perhaps you should ask yourself under what circumstances you believe the spindle speed needs to be deadly accurate? You are talking about achieving a recommended surface speed at the cutter somewhere in a range of 2 or 3 to 1. Many VFDs can be set up to compensate for slip frequency so that the spindle barely slows under load - if you continue to believe that's critical.