New mill, which motors?

[Robin Hewitt]

I am a bit out of touch, what is good in stepping motors these days? Have they improved?

Robin

[Voicecoil]

Closed loop types seem to be much more affordable now, and would be my route of choice, less chance of losing steps when going hard.

[pippin88]

Budget? Consider servos: Delta AC servos are excellent.

[Robin Hewitt]

I was thinking more along the lines of £100 per axis.

I saw closed loop on Bang Good for £46 per axis, is that the ones?

I'd like 5um per half step so I'm thinking 2:1 down on to a 4mm screw. I ordered 3 screws and 8 nuts with custom end machining from Wendy Wu. The FedEx costs more than the parts

[Muzzer]

How do you plan to drive the Z axis? On a Bridgeport head you have access to the quill via the feed stop but on your rather nice machine I don't see anything like that. Some sort of collar on the base of the quill?

[Robin Hewitt]

Absolutely right, it has to be the quill for the Z axis but I haven't figured out how to do a quick release for drilling. Needs thinking about.

[Muzzer]

I originally planned that on my Bridgeport conversion but after using my CNC-only Shizuoka for a while (it never had any handwheels), I decided that for me there's no point retaining manual controls when you have a wireless MPG. This achieves the same effect (handwheel controlling quill and table movement) yet can be used almost anywhere. You also get consistent and deadly accurate operation with DRO readout and the moment of inertia of the X&Y handwheels wasn't improving the servo responses on my system. I often do manual operations using the MPG such as squaring up stock, slotting, drilling holes etc.

I'm starting to have similar thoughts about my lathe conversion, having started out planning to retain all manual controls. Instead I think I'll keep the manual parts in case I sell the machine and go fully CNC.

[JAZZCNC]

What Nema Size you wanting Robin 23/24 or 34's.?

I've got some Lichuan Nema 24 5.5Nm 2 phase closed loop with 70V AC or 100Vdc drives with 3Mtr cables which I'm offering to Forum members. £125.00 plus postage.

https://www.aliexpress.com/item/1005...568f4df8dMSFFL


Also got some Closed loop 10Nm 3 phase Nema 34's using Mains voltage drives but those might be a little too large and expensive.
These are great for large machines where high speed isn't required and simplicity is prefered to more complicated servo's. The motors are nice and smooth being 3 phase and with being mains drives they still spin at resonable rate with good torque at higher rpm's. The closed loop makes them nice and reliable in position terms.

If you don't require what Servo's offer then they are good option and pretty much plug n play with no messing around tuning etc.


https://www.aliexpress.com/item/3279...42906f37My63lC

[Robin Hewitt]

Good question, no good answer, I don't know what I want...

High speed may be preferable to high power?
Cool running is nice.
A sexy power against speed graph that doesn't fall of a cliff could get my juices flowing.
Something that doesn't come in sets of 3 is handy because X and Z can be very different.
I do know it will drive a 4mm ball screw using timing pulleys, I have a thing about XL pulleys

[JAZZCNC]

Good question, no good answer, I don't know what I want...

High speed may be preferable to high power?
Cool running is nice.
A sexy power against speed graph that doesn't fall of a cliff could get my juices flowing.
Something that doesn't come in sets of 3 is handy because X and Z can be very different.
I do know it will drive a 4mm ball screw using timing pulleys, I have a thing about XL pulleys

Robin modern Digital drives are completely different animals to old Analog drives, they are light years better and run motors much cooler with much much smoother operation.
The minute the motor spins you'll understand what I mean because they sound very different as well, much quieter. And with the newer closed-loop, esp the 3 phase motors, they have taken another, if slightly smaller leap forward.

You'll find with the new breed of steppers/drives you get higher rpm's and they carry the torque higher up the curve. Also. with most of the drives allowing AC connections, you don't have to mess around building DC PSU, just hook them up to a transformer, and away you go.