What's the minimum I need for a small lathe?

[friolator]

I just bought a Denford Microturn lathe built around 2002. This is based around a Sherline 4000. I will be using it to machine primarily Delrin and HDPE parts, all pretty small. I haven't received the machine, it's arriving next week. There is no software included so I'm expecting that I'll have to retrofit my own controller. I've done this kind of thing before with a CNC Router and a Masso controller.

This is for use in our office. The parts I'll be making are primarily rollers for motion picture film equipment - pretty straightforward profiles, typically with a hole bored down the center to accept a shaft/bearings. It's unlikely I'll be threading anything but that'd be fun to have.

We've got plenty of PCs and a box full of stepper motors and drivers and power supplies. I may swap out the spindle motor with a Teknic Clearpath we have from an unrelated project, but that's TBD - I haven't seen this close up so I have no idea what would be involved. I have no idea if the default motor has an encoder on it, but I could probably add one (recommendations?). I'll likely add an MPG pendant, and there is an E-Stop on the machine. I would probably remove the existing spindle speed controller and just do that from software. I assume there are limit switches, but if not I'd add them.

So what is the minimum I'd need on the Acorn side for this? And if there are older models that would work, what would you recommend? i'm not opposed to picking up something used if it'll save me a few bucks.

Thanks!

[cnckeith]

PC
Acorn Kit
axis drives and motors
spindle encoder
limit/home switches
estop button

make a photo album of the machine and all the stuff you have and post a link to the google photo album here so we know what you have.

[friolator]

I will have better/more pictures when it arrives, but in the mean time, below are the photos from the seller. There's a fair bit of cleanup to do, so I may end up taking a lot of this apart, which will give me an opportunity to take some more pix.

I already have everything on the list above except for the Centroid Acorn hardware. Is there an older version that would be suitable for this kind of machine that I could pick up used? Trying to do this on a budget...

For example - I don't see the Centroid Acorn for sale on its own, only in a kit with power supply, relay board, cables, etc. I have all that other stuff, I'd just need the Acorn controller. Maybe I'm missing something?

[friolator]

I spent some time looking up the specs of the Sherline and then digging through our closet here, where we have a lot of steppers/drivers/power supplies, etc. It certainly seems like you can't get the Acorn board on its own and I can't find any used ones at a price attractive enough to convince me to buy it over a new one, so I ended up buying the kit. It'll be here Monday, a day before the Lathe. We have a 1920x1080 touchscreen display that will hopefully work, as well as an i3-based Mini PC that's no longer in use. I also have closed loop stepper/driver setups that happen to be NEMA23, so I'm planning to replace the stock motors with those because ...why not?

My hope is that this is constructed like the newer model Denford machines, which have a big open space to mount DIN rails in the back.

I'm not sure the Teknic motor we have will have enough torque to drive the spindle, but assuming it does, do I still need an encoder, or can the Acorn get position information from the Clearpath?

[friolator]

The Teknic motors we already have are:

CPM-CMPV-2311S-ELN
CPM-CMVC-2311S-RLN

[cnckeith]

hello!

the encoder in my list above is for the spindle not the axis motors

clearpath motors have their own encoders built into the motor in which they use to close the loop to their own drive. Acorn just send signal to the clearpath drive on where to be when and they close the loop on that.

as far as toque goes, contact teknic for their recommendations on that. they are great at helping users with matching up the right motors for the machine.

[friolator]

the encoder in my list above is for the spindle not the axis motors

Yeah. I'm referring to the spindle. Right now it's the motor that Sherline ships with the 4000 model lathe. I have no idea if Denford added an encoder to this lathe but I don't believe it comes with the Sherline if you were to buy that directly. I would be replacing the stock spindle with the Teknic if I can, or possibly with a hybrid closed loop stepper/servo.

clearpath motors have their own encoders built into the motor in which they use to close the loop to their own drive. Acorn just send signal to the clearpath drive on where to be when and they close the loop on that.

I'm thinking ahead - if I want to do threading, I need the spindle to have an encoder correct? Are you saying that if I use the Teknic motor for my spindle I no longer need the encoder because the Acorn just sends the signal to the motor and that's that?

as far as toque goes, contact teknic for their recommendations on that. they are great at helping users with matching up the right motors for the machine.

Yeah they're great. We use three of their motors in a film scanner we built: two MCVC NEMA34s for the feed and takeup of 70mm film, and a NEMA23 SDSK for a capstan drive. The three NEMA23 extras I have are from when we had to send a mini version of the machine out to a firmware developer for debugging the controller. These aren't cheap motors which is why I'm hoping I can find a home for one in the lathe.

[cnckeith]

the encoder in my list above is for the spindle not the axis motors

Yeah. I'm referring to the spindle. Right now it's the motor that Sherline ships with the 4000 model lathe. I have no idea if Denford added an encoder to this lathe but I don't believe it comes with the Sherline if you were to buy that directly. I would be replacing the stock spindle with the Teknic if I can, or possibly with a hybrid closed loop stepper/servo.

< hybrid closed loop with Acorn on a Lathe is the recommended way to go. open loop sucks for threading and is limited in speed and accell control>

clearpath motors have their own encoders built into the motor in which they use to close the loop to their own drive. Acorn just send signal to the clearpath drive on where to be when and they close the loop on that.

I'm thinking ahead - if I want to do threading, I need the spindle to have an encoder correct? <yes 1:1 with the spindle itself! >, Are you saying that if I use the Teknic motor for my spindle I no longer need the encoder because the Acorn just sends the signal to the motor and that's that? < No>

as far as toque goes, contact teknic for their recommendations on that. they are great at helping users with matching up the right motors for the machine.

Yeah they're great. We use three of their motors in a film scanner we built: two MCVC NEMA34s for the feed and takeup of 70mm film, and a NEMA23 SDSK for a capstan drive. The three NEMA23 extras I have are from when we had to send a mini version of the machine out to a firmware developer for debugging the controller. These aren't cheap motors which is why I'm hoping I can find a home for one in the lathe.

[friolator]

Ok thanks. Last question (for now at least)...

How does the Acorn control the spindle speed? does it send step and direction pulses to the spindle motor, or some other mechanism?

[cnckeith]

Ok thanks. Last question (for now at least)...

How does the Acorn control the spindle speed? does it send step and direction pulses to the spindle motor, or some other mechanism?

No

0-10 vdc analog out is the spindle speed command. see the Acorn installation manual "spindle speed bench test" section.

step and direction for spindle speed output may be a feature in a future CNC12 release.