Building a CNC Lathe

[m_c]

Those photos are closed loop steppers, which technically are still servos.
Essentially any electric motor that runs under closed loop control is a servo, although servo is usually taken to mean a non-stepper motor based system.

I've never went as far as using closed loop steppers, for the reason every machine I've considered using them for, I've never bothered upgrading from the original steppers, and all the bigger machines would be crippled by steppers.

However, those are 3 phase steppers, which although they do still cog, run far smoother than more common 2 phase stepper motors, and can be pushed that bit harder than an equivalent 2 phase. They do still suffer from torque drop-off, but for this size of machine, I'd say they're an ideal fit. They won't be the fastest, but when you've only got 9" of travel, low speed torque for acceleration is far more important than outright speed.
Only thing is, going for a 2:1 reduction for the Z axis may give better acceleration, given the inertia involved with spinning two ballscrews, however I'd try it direct drive first.

 

[Hood]

Those photos are closed loop steppers, which technically are still servos.
Essentially any electric motor that runs under closed loop control is a servo, although servo is usually taken to mean a non-stepper motor based system.

I've never went as far as using closed loop steppers, for the reason every machine I've considered using them for, I've never bothered upgrading from the original steppers, and all the bigger machines would be crippled by steppers.

However, those are 3 phase steppers, which although they do still cog, run far smoother than more common 2 phase stepper motors, and can be pushed that bit harder than an equivalent 2 phase. They do still suffer from torque drop-off, but for this size of machine, I'd say they're an ideal fit. They won't be the fastest, but when you've only got 9" of travel, low speed torque for acceleration is far more important than outright speed.
Only thing is, going for a 2:1 reduction for the Z axis may give better acceleration, given the inertia involved with spinning two ballscrews, however I'd try it direct drive first.

Aye but @northwest is intending to use it, for a spindle I think.

 

[m_c]

Aye but @northwest is intending to use it, for a spindle I think.

He's not using a Nema 23 for the spindle.
Spec for the steppers is here - http://servo.xlichuan.com/prod_view.aspx?TypeId=74&Id=187&FId=t3:74:3

IIRC he was going for something around 1KW for the spindle.

 

[Hood]

Read that way to me but...

 

[northwest]

Seems it is, not sure how suited to a spindle it will be, would imagine the max rpm would be limited to about 1000rpm.
Then again I know nothing about closed loop steppers, I think @m_c has used them before.

i hve a 1.2kw 3000rpm monster of a servo for the spindle, pics later.
these ikkle dits Nema23 servo's are they that wot I was on about, going to probably retrofit them to the Mill which has nema23 sterppers on it at the moment. Will order up a servo closer to your dimensions for the Z axis and try to work out(need a ballscrew remember?) what I need for the X axis and buy accordingly, or not as the case may be.

 

[Hood]

Ok, just when you said your servo arrived for the spindle and then posted a pic of the stepper

 

[Onoff]

totally missed the keyboard layout, a recipe for disaster, WHY can't we have just ONE standard?

Those keyboard keys should just unclip, then arrange them how you want.....

 

[Hood]

Those keyboard keys should just unclip, then arrange them how you want.....

It will be a single membrane over a pcb with switches on it so no way to swap around as far as I can see but the layout makes perfect sense for a CNC anyway. If you were typing forum posts on it then it could be problematic but ....

 

[Onoff]

It will be a single membrane over a pcb with switches on it so no way to swap around as far as I can see but the layout makes perfect sense for a CNC anyway. If you were typing forum posts on it then it could be problematic but ....

Sorry, I said it in jest!

 

[Hood]

Sorry, I said it in jest!

LOL well you missed out the "in jest" emoticon

 

[northwest]

That's not a Servo, This is a Servo:

 

[Hood]

Actually this is a servo, for a size reference compare it to the 5 gallon drum in the background

 

[northwest]

Actually this is a servo, for a size reference compare it to the 5 gallon drum in the background

I will give you that one!

 

[Hood]

I will give you that one!

Sadly the 22kw servo drives weren't very reliable, had 4 of them die so ended up taking it off and going back to the 12kw induction motor and gearbox. Still have it in the hope that one day I can find a cheap servo drive that will run it but...

 

[northwest]

IT'S ALIVE, well it powered up, the Control panel that is, in order for IT to actually work I would need it all to be connected together and THAT'S not happening this week, but the controller is all working and I can now start to learn the functions, I won't of course but I could if I wasn't so busy trying to bolt the rest of it together!

 

[northwest]

The chuck is stuck, I mean really stuck. Realising that if this happens when the machine is all built up I will be screwed I have decided to dismantle the sindle and from what I know the spindle wil come out with the Chuck attached I am going to stick it in the Mill and machine two flats on it for a spanner:

I am starting to get on with this so this setback has put a spanner in the works, literally.

 

[Hood]

There should already be two flats on the spindle.

 

[Munkul]

I am starting to get on with this so this setback has put a spanner in the works, literally.

It seems to me the problem is actually a lack of spanner in the works

 

[Hood]

One easy way to get the chuck off is full speed on the servo then rapid stop. Be ready to catch the chuck

 

[Seadog]

Isn't there at least one flat at the rear end visible in the picture?