[binfordw]

Ive been spending a fair amount of time improving my old Grizzly G0463 mill lately, and have been wondering about an improved spindle motor/control setup..

I currently run the stock motor, a claimed 3/4hp brushed DC motor, and replaced the crappy control with a Dorner DC controller (An Industrial conveyor control). This has proven much more reliable than the original control (I had replaced a few), but I do get spindle speed variation when entering "heavier" cuts.

What would be a good option for replacing the stock motor and drive? I've read a bit about a cheap servo motor and controller, I mainly want less (alot less) speed variation in cuts, and the ability to control speed through Mach3.

[Azalin]

Best option would be a slightly faster AC servo I guess. I installed a Schneider 1.13kw servo and ABB drive to my BF20L mill. I control it by velocity mode. I'm happy so far.

I know people also use treadmill motors on mini lathes because their small volume. I used one in my mini lathe as well.

Sent from my MI 5s Plus using Tapatalk

[joeavaerage]

Hi,
AC servos are very power dense and have very generous overload allowances (in brief spells of course) and make excellent spindle motors. They are not cheap though.
Do not buy an el-cheapo one, it will drive you up the wall trying to get it to go.

I use Delta servos, as axis servos, but they would be equally good as spindle motors. Delta is a Taiwanese brand made in China with good quality, performance, support, documentation and
most importantly free setup and tuning software at fair prices. I use these 750W (1hp) servos on my machine and have bought three in the last year alone:

://www.fasttobuy.com/flange-80mm-239nm-ac-motor-driver-kits-with-3m-cable-220v-075kw-cnc-servo-motor-for-cnc-router_p28084.html

There are cheaper Chinese made servos, but if you have not used servos before I'd recommend paying extra for Delta or DMM (Canadian brand made in China), the quality and support and the setup and tuning software
are pretty much essential for your first servo.

Craig

[joeavaerage]

Hi,
I actually made a spindle a few years back using a second hand Allen Bradley servo 1.8kW, 6.1Nm (cont), 18Nm (overload), 3500rpm.
I mated it to an ER25 tool holder running in P4 angular contact bearings.

I've used it a lot for steel and stainless where you need slow(ish) speeds but high torque.

I was very careless and had this in the bottom of my mill enclosure when it was not in use and coolant got into the encoder and wrecked it. I have yet to save up the money to
repair or replace it. Very stupid and very careless of me.

Craig

[binfordw]

So I'm still looking for the best option to improve my spindle motor setup,

It seems like the DMM drive/servo setup is one of the best options for me, but its close to $1,000. The only gains would be better speed control, probably more spindle power, and the ability to control speed through mach.

I found Steppers online sells a cheap servo/drive kit as well, that looks to be well documented. https://www.omc-stepperonline.com/t6...s1000h2b3-m17s

It would be a bit less power at 1kw, compared to the 1.3kw/1.8kw options DMM sells, but I'd imagine a 1kw will be noticeably stronger than my current setup. Anyone have thoughts on these?

[joeavaerage]

Hi,
it is typical of many cheap Chinese servos. I have no reason to doubt that it works, and a quick scan of the manual suggests that its better than average. There is no clear indication to me
that there is setup and tuning software, and you'll need that. Look at the parameter descriptions, there are hundreds upon hundreds of them. Programming the drive by pushing buttons on the
panel like a microwave is too tedious and error prone, not impossible, just nearly impossible.

If its got software then try it, if it has not then I'd recommend finding another brand which does.

Craig

[Azalin]

I had worse. It was a pain but I managed an AASD servo and drive to work as spindle motor on my lathe. Position mode worked well except threading cycle in Mach4. That was because PoKeys does not support Mach4 threading when the motor is in position mode. So I switched to velocity mode.

I believe the DMM is easier than AASD.

Sent from my MI 5s Plus using Tapatalk

[joeavaerage]

Hi,
I use 750W Delta servos and I pay $438 plus shipping for them. I've bought four within the last year which including three day Fedex to New Zealand from Hong Kong,
costs $588USD per unit. Because they are such a common size there is a discount, they would ordinarily be about $550 plus shipping.
Would 750W (1hp) be enough?

Craig

[binfordw]

Hi,
I use 750W Delta servos and I pay $438 plus shipping for them. I've bought four within the last year which including three day Fedex to New Zealand from Hong Kong,
costs $588USD per unit. Because they are such a common size there is a discount, they would ordinarily be about $550 plus shipping.
Would 750W (1hp) be enough?

Craig

I currently have a 3/4hp dc brushed motor, and a controller that doesn’t modulate speed well. So with much load, it will slow, then ramp high, and repeat.

I’d assume a 3/4hp ac servo would still be a welcome improvement in all aspects.

First- I want to remove the high/lo gearset- it’s noisy as can be. With a 3k rpm servo and a direct belt drive to spindle, the noise would be a huge improvement. Plus, rpm would be similar/or possibly better depending on pulleys.

I’d like the option of enough power for rigid tapping at a later date if things went well, but, it’s not a big concern currently.

[joeavaerage]

Hi,
personal experience is that the 750W servos are nominally 1hp, so a small increase on what you have, but because of the very generous overload characteristics often
behave as if they have more power than the nameplate suggests. The overload potential can be exploited but only for brief periods of time. A 750W servo will attempt to deliver
900W say, but will in all probability overheat, so they are good, but not magic.

The stability of rpm relative to load is extremely good. I would expect this of all servos, not just these Delta's. Modern AC servos are going to blow you away with their performance.

My Delta's are rated to 3000 rpm, that is to say they maintain 2.4Nm up to 3000rpm, but can in fact go faster, up to 5000rpm, but at reducing torque.

Torque at 5000 rpm= 2.4 x (3000/5000)
=1.44Nm

This feature, again common to many AC servos, is called 'field weakening', and is a interesting ability of Field Oriented Control on which AC servos rely.

I’d like the option of enough power for rigid tapping at a later date if things went well, but, it’s not a big concern currently.

I have done rigid tapping with my Allen Bradley servo driven spindle (6.1Nm cont, 18Nm overload), but you need a surfeit of torque to do rigid tapping or it will fail.
I've had more cock-ups and failures trying to get rigid tapping to work than anything else. If you measure that 2Nm is required to manually drive a 6mm tap into a particular
piece of material with a given size hole (ie known thread engagement) then you'll want at least double the torque from the spindle or your can expect trouble.
I would not expect that without significant gear reduction and consequent torque multiplication that you could do any useful rigid tapping with a 750W servo.

With low torque spindles thread milling is a better bet.

craig

[metalmayhem]

https://glockcnc.com/store/#!/Spindl...rade/c/8597972

glockcnc has a brushless 750w and 1200w setup

I bought the 1200w for my g0704 . I scrapped the mill shortly after hooking it up so I had it running well but never took cuts with it . I had the spindle setup to run off belt drive at 6000rpm and the speeds were controlled through pathpilot . In comparison the tormach 440 uses a 500w which isn't lacking within reason .
I've been seeing more and more similar setups on aliexpress these days .

[binfordw]

After more looking into the stepper online servo kit, it does have tuning software available for it. I'm going to do some more thinking, but it would get me a 1000W servo for about $450 shipped.