Ralph 12 Nm is a beast if you run it at its rated current. I have one on my mill and managed to shear a drive key using the stepper at full rated current. Fortunately the stepper drive has lower current settings.....its on about half rated current now.
Don’t (how do I know ? ) use it at full current with out a trip switch to prevent end stop crashes.

By the way with Lindo’s corollary.....tools are not the only things cats make off with ! interesting curls of steel and aluminium also walk too. And they end up in funny and not so funny places....a freshly made bed ?
And of course O’flanagan held that Murphy was an optimist.

Regards ?Bob

Why worry about the spindle stopping, I thought that the problem was the use of high torque? motor driving the leadscrew. A limit switch will stop that. Be aware that it is not good policy the have a high deceleration rate on a spindle with a screw on chuck!
I need to say that I have had an ELS for quite a few years and have never crashed it yet!
Richard

On 24/09/2020 14:05, Ralph Hulslander wrote:

Interesting thanks, I only bought the motor because of the sale.

I "plan" on having travel stops, but do not know how to get my spindle to fast stop.

I use the and there is very little known about the controller.

I am currently?using a 10 k pot in place of the Hall Effect foot pedal and when I turn the pot down there appears that there might be braking

involved. If I just turn the power off the motor continues to? rotate.

Ralph

On Thu, Sep 24, 2020 at 7:26 AM Bob T <zs6bxi@...> wrote:

Ralph 12 Nm is a beast if you run it at its rated current. I have one on my mill and managed to shear a drive key using the stepper at full rated current. Fortunately the stepper drive has lower current settings.....its on about half rated current now.
Don’t (how do I know ? ) use it at full current with out a trip switch to prevent end stop crashes.

By the way with Lindo’s corollary.....tools are not the only things cats make off with ! interesting curls of steel and aluminium also walk too. And they end up in funny and not so funny places....a freshly made bed ?
And of course O’flanagan held that Murphy was an optimist.

Regards ?Bob

--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer

On Thu, Sep 24, 2020 at 07:42 AM, Ralph Hulslander wrote:

As I have said I flunked out of Machine shop II 55 years ago and have never touched a machine since.

For someone who hadn't touch a machine since, you have quite a few machines in your workshop! Were you just collecting them for a while, and now starting to touch them? :)

Immediate stop could be useful when you hit the emergency stop button. Like mentioned already, might be not a good idea if you have a screw-on chuck, as it can unscrew during a sudden stop. If you had a 3-phase motor and a VFD, most VFDs have a fast stop option (some faster than others, using an external brake resistor). No idea if that's possible with a motor like yours. I've heard that bigger lathes can have mechanical brakes as there is a lot of energy to dissipate quickly.

"I need to say that I have had an ELS for quite a few years and have never crashed it yet!
Richard"

Unlike Richard, who is an outstanding machinist and whose level of expertise I shall never come close to achieving, I have crashed my RELS system once. It was 100% my fault, not the system's. The point I want to make is that I use a NEMA 23 stepper with 3.0 Nm holding torque on both the Z and X axes. When I incorrectly drove the cutting tool straight into the part with the cross-slide at relatively high speed, my X-axis stepper never stalled. I managed to hit the Emergency Stop button, which on my mini-lathe disables the mains power, before any? damage was done. The stepper motor torque was sufficient that it spun my QCTP about 30 degrees around its M12 (or is it M10? I can't remember) mounting bolt. I can't imagine what kind of damage a 12 Nm stepper could cause!

I view the stepper motor partly as a kind of mechanical fuse, and prefer that it stall rather than cause more permanent damage.
--
Regards,

Charlie
New Jersey, USA

?

ANTHONY’S LAW OF THE WORKSHOP: Any tool, when dropped, will roll into the least accessible corner of the workshop.

THE LINDO COROLLARY: If you have cats, they will promptly hide the tool.

I’ve been playing with various stepper motor sizes and torques.?
I do have a 12 Nm stepper on my mill and have just upped the the sizing on my Hobbymat MD 65 Z drive from a 1 Nm to a 3 Nm drive nema 23 and from a 0.4Nm to a 0.65 Nm nema 17 on the X axis. My take on sizing (for what its worth) is that the larger the torque rating you have on a stepper the larger the “cogging” effect you feel when you turn it without the power connected. The 3Nm nema 23 on my Z axis has gotten just a little too big to be comfortable turning it when I’m not using the stepper drive (the hand wheel is 60 mm dia). On the other hand my 12 Nm beast works well with a 100mm dia. hand wheel without power on. I suspect that the “clogging or detent” effect varies with with the supplier and the length/diameter ?ratio of the stepper motor rotor. Of course any gearing will amplify the effect. For interests sake when I was “commissioning” my new ?X axis drive I put a digital dial gauge on the cross slide and measured what actual movement hat I was actually getting as I put steps on the motor. I was surprised to find that although a complete revolution of the stepper motor was a constant the angle change for a given number of steps did vary a bit.....probably in line with the spec sheet on the motor that said 5% linearity, not a problem for most folks but I will be looking at doing a 2 or 3 reduction in drive ratio to improve that.If I do that then I will have to look at a neat way of dis-engaging the drive when I don’t want it connected. It never ends !
The stepper in line folk also have a depot or agent in Australia so I get good response (and prices ) from them. But when you get to the larger sizes of stepper and drive things are no longer “cheap”.

Regards Bob

Ralph, it would help if you "Replied" to the original mail!
As Peter has said OTT is "UK English" for Over the Top, meaning, a lot more than necessary.
In your case OTT referred to your suggestion of using a 3Nm motor with a 6:1 drive on your 1/2" 10tpi X leadscrew.
There are a number of problems with such a setup. First is adding the complication of a belt 6:1 ratio drive.
Secondly that amount of torque is just not needed. Thirdly as Bob indicates below the detent torque becomes a pain when working manually.
My X screw is 12mm x 2.5mm pitch so very close to yours and I have a 1.85Nm direct driving it. The detent torque is acceptable though there are times when I just unplug the motor to get rid of any loading. I have never had any cutting problems with my X feed though I do not take 5mm facing cuts in steel! I would suggest that you use your 3Nm motor but with an inline 1:1 drive.
Richard

On 26/09/2020 00:29, Ralph Hulslander wrote:

The X leadscrew is 1/2-10.

What is OTT?

Ralph

On Fri, Sep 25, 2020 at 6:33 PM Bob T <zs6bxi@...> wrote:

I’ve been playing with various stepper motor sizes and torques.?
I do have a 12 Nm stepper on my mill and have just upped the the sizing on my Hobbymat MD 65 Z drive from a 1 Nm to a 3 Nm drive nema 23 and from a 0.4Nm to a 0.65 Nm nema 17 on the X axis. My take on sizing (for what its worth) is that the larger the torque rating you have on a stepper the larger the “cogging” effect you feel when you turn it without the power connected. The 3Nm nema 23 on my Z axis has gotten just a little too big to be comfortable turning it when I’m not using the stepper drive (the hand wheel is 60 mm dia). On the other hand my 12 Nm beast works well with a 100mm dia. hand wheel without power on. I suspect that the “clogging or detent” effect varies with with the supplier and the length/diameter ?ratio of the stepper motor rotor. Of course any gearing will amplify the effect. For interests sake when I was “commissioning” my new ?X axis drive I put a digital dial gauge on the cross slide and measured what actual movement hat I was actually getting as I put steps on the motor. I was surprised to find that although a complete revolution of the stepper motor was a constant the angle change for a given number of steps did vary a bit.....probably in line with the spec sheet on the motor that said 5% linearity, not a problem for most folks but I will be looking at doing a 2 or 3 reduction in drive ratio to improve that.If I do that then I will have to look at a neat way of dis-engaging the drive when I don’t want it connected. It never ends !
The stepper in line folk also have a depot or agent in Australia so I get good response (and prices ) from them. But when you get to the larger sizes of stepper and drive things are no longer “cheap”.

Regards Bob

--
Clausing 8520, Craftsman 12x36 Lathe, 4x12 mini lathe, 14" Delta drill press, 40 watt laser, Consew brushless DC motors and a non working 3D printer