Centroid Community CNC Support Forum

Hello everyone. This is my first post and I'm in the process of converting a Little Machine Shop 7350 7x16 mini lathe to cnc. I found Franco's lathe conversion kit that he open sourced and I am using his plans for a few of the parts (ball nut mount for the z axis, x axis motor mount, z axis ballscrew and motor mount, and his carriage design).Also through Franco and his YouTube page I discovered Centroid Acorn and well here I am lol. I ended up buying a 600mm ballscrew and then realized I need a 750mm ballscrew for the z axis so I will be exchanging those. I got a 12mm ballscrew for the x axis and plan to open up the factory hole for the lead screw to sneak the bigger screw through and will be mounting the ball nut off the back of the cross slide.

Here is a list of parts I have so far to get everyone up to date as to where I am.

Centroid Acorn Motion Control. No need to link that one.

I am gonna use a DB25 Breakout Board to wire in the DM542 Stepper Drivers to Nema 23 420 in oz steppers.
Stepper Drivers: https://www.amazon.com/gp/product/B07PH ... UTF8&psc=1
Stepper Motors: https://www.amazon.com/gp/product/B00PN ... UTF8&psc=1
DB25 Breakout: https://www.amazon.com/gp/product/B073R ... UTF8&psc=1
Encoder: https://www.amazon.com/gp/product/B01EW ... UTF8&psc=1
Power Supply: https://www.amazon.com/gp/product/B08GF ... UTF8&psc=1

I am running the stock 500w brushless .7 HP motor for now. I had thought about going with a VFD and a 3 phase motor but for now I just wanna get it running and maybe swap later.

So with all of this and the Acorn board I thought I was ready to go until I saw LMSCNC thread and him and Marty started talking about isolation and smoking the acorn board. I then found Franco's YouTube video about the KBSI240D and thought alright this should work. I'm still unsure if I need the CNC board from LMS which from LSMCNC thread and contraction LMS myself they are actually useless in the knowledge department of that product. I was talking with a friend that is an electrical engineer and was doing some digging and found CNC4PC.com and their spindle control boards that isolate out the signal from the Acorn board as well and I like that option but I'm still not sure how to hook it all up.

https://www.cnc4pc.com/c69-pwm-spd-contrl-board.html

This is the spindle control board I am looking at. I am gonna use the DB 25 Breakout board to run signal to the drivers for the stepper motor. Being that I have the breakout already can I wire the C69 board into the breakout if I get another breakout for the C69? Sorry if this is confusing but I'm confused as well.

Anyways I have some pics of the first two Franco parts I have made. Did these on my buddies Haas DT-1 and he is teaching me CAM programming in Fusion360 and how to set up and run the Mill.

hello. thanks for posting, looks like great project. I highly recommend closed loop motors/drives for lathe applications. at this day and age there is no advantage to using open loop motor especially on a lathe.

cnckeith wrote: ↑Sun Feb 13, 2022 5:32 pm hello. thanks for posting, looks like great project. I highly recommend closed loop motors/drives for lathe applications. at this day and age there is no advantage to using open loop motor especially on a lathe.

Would I still run closer loop system off the DB25 on the acorn? And where would the feed back for each axis wire into the board?

The closed loop is between the motor and drive. The drive would output an alarm signal to the Acorn in the event of an error. There is no position feedback between the drive and Acorn.

tblough wrote: ↑Sun Feb 13, 2022 8:53 pm The closed loop is between the motor and drive. The drive would output an alarm signal to the Acorn in the event of an error. There is no position feedback between the drive and Acorn.

Ahh gotcha. Thank you very much.

The electrical is killing me on this one. I can wire a Harley from scratch, car stereo sound system no problem. All this automation I’m in over my head.

Thank you for sharing your pictures. Franco has inspired me also, I am converting a 7x lathe also, but it is "Cowboy style" (Parts manually made).

Miamijerry wrote: ↑Mon Feb 14, 2022 9:10 am Thank you for sharing your pictures. Franco has inspired me also, I am converting a 7x lathe also, but it is "Cowboy style" (Parts manually made).

I was gonna make them on my Bridgeport but my buddy has a cnc mill and lathe and I have been running the lathe to help out and he wanted to train me on the mill so he used my parts to train me.

I will keep the pics coming as I go. Hoping to have this knocked out by April or so.

So I got all the cnc parts done last night. I’m just waiting on the correct ballscrew to come in then I can mount that and be off to the races. Getting excited now.

I have been talking to miamijerry and decided I am gonna use the kbsi240d for isolation.

Starting to think about and electronics enclosure now. Should I test everything first then build a box or build the box first and hope everything works well?

iLefty

We have been discussing the electronic wiring for a 7x lathe by PM

I am planning on using;
KBSI-240d for 0-10v isolation.
A "manual / CNC" switch installed in the lathe control box, (provides the ability to use the lathe manually) and
An inhibit relay, controlled by Acorn which will close the wires connected to SW2 (Pin 3 and 5) in the attached PDF.
(Note, with an inhibit relay, SW4 is simply a SPDT and does not close pin 3 to 5)

I don't need reversing relays, but if I do need reverse at some point in time, I will upgrade to a KBCC-125R
You can find more information about the KBCC-125R here;
https://centroidcncforum.com/viewtopic. ... bcc#p10067
https://centroidcncforum.com/viewtopic. ... 402#p12402

I got a bit of time this morning to start adding on the z axis ball screw. I have to trim it just a tiny bit and my thrust bearings are coming in soon.

As per Keith’s suggestion I switched over to closed loop stepper motors and one came in yesterday the other is coming tomorrow.

Then to start on the x axis ballscrew fitment and then electronics.

And I don’t know why the pictures keep posting sideways.