All of this discussion is really good to read.
The question I have is how do you determine the torque?
I do not have another machine available for reference just a manual mill and lathe.
I was doing some side milling (@ 1" with 1/2" end mill on mild steel) the other day and I was surprised how much torque, I was really having to crank it.
Doing end cuts I really have not noticed the torque but side milling really made a difference.
So if I wanted a powered X or Y on my mill how would I determine the required torque and then all of the other info
from this thread.
Ralph
was required
On Thu, Mar 22, 2018 at 6:50 PM, Chris Albertson albertson.chris@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
Yes, I know the original reason for the extra wires but I was trying to explain them in today's context. No noe trying to gain efficient use of a motor is going to give up on using a modern driver and so back to simple switches. So given that you will be using a modern-style driver, the only use of all those extra wires is to adjust the impedance for your use case. But of course if you are buying a new motor why adjust it? Just buy what you really need. I agree, anything with more then four wires is obsolete. But lots of old salvaged motors on my arts does are 6 and 8 wire motors.I have built low power switched drivers. They are easy, four 2N2222 transistors and not much else but it no longer makes sense to do this when you can get low power drivers for $4. or high powered ones for $50.While we are beating this subject to death there is one important motor specification not yet discussed: Coil inductance. Inductance is a coil's resistance to change in current. It is analogous to resistance in DC circuits.. Choosing a coil inductance is to complex for amateurs. Don't bother. Look at the torque curve. It is that curve you care about anyways.Today if you are a normal user (not an electrical engineer) you will be interfacing to the driver. It has just wo pins "step" and "direction" All this other stuff don't matter. Motor inductance, number of wires, resistance. Yu don't deal with it. Just place a toggle switch on the "direction" pin and and some kind of pulse maker not h"step" pin.On Thu, Mar 22, 2018 at 12:11 PM, 'Tony Smith' ajsmith1968@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups..com > wrote:It's not really about choice; 6 & 8 wire steppers (unipolar) are easier to control, but are basically obsolete due to 4 wire (bipolar) drivers becoming cheap.
To spin a 6 or 8 wire unipolar motor you just need to turn each coil (4 of them) on one after the other, very easy to do. Even by hand!
For 4-wire bipolar you only have two coils, but you need to reverse the voltages as well switch them on & off, a bit trickier (aka expensive) to do.
The thing we usually care about is a bipolar motor will have more torque than the equivalent unipolar one. Unipolar still has some applications, but it's stuff where high speed (in stepper terms) matters, or for really low-end cheap stuff (and even a lot of that is going away).
Tony
From: 7x12minilathe@yahoogroups.com [mailto:7x12minilathe@yahoogroups.com ]
Sent: Friday, 23 March 2018 4:53 AM
To: 7x12minilathe
Subject: Re: [7x12minilathe] Re: Mini-Mill CNC, First Test of X-Axis.
Those 6 and 8 wire motors have 6 or 8 wires for a reason. If gives the user a choice.
All motor have two coils. If they run the ends of the coils out of the motor there are four leads (as each coil has two ends) this is the normal case.
But what if you place a center tap in each coil? Now you have six leads. Why one Earth make a center tap? It gives the user a choice
(a) he can ignore the center tap and even cut the wire off and have a four lead motor or
(b) he can use only 1/2 of the coil feeding power from the center to one end. Of course this makes the motor half as powerful but it can also rotate faster with coils that have much less inductance
(c) there are other options but they don't apply unless you are designing your own motor driver which is a specialist engineering job.
With 8 lead motor they go one step farther. Rather then center tapping each coil they cut it in half now you have three options.
(a) connect the cut coils back together and make a normal four lead motor
(b) use just one of the half coils (not a great option because as in "b" above the motor is only 1/2 as powerful.
(c) use both half coils in PARALLEL. This is a very attractive option as it greatly reduces the coil inductance as in "b" but lets you use all of the motor's designed power.
If yu download the PDF manual for the driver it explains this.
But in ALL of the above cases the driver sees only four leads because you have connected them, cut them off or whatever before connecting to the driver. So in effect all motors have only four leads
Most motors have 4 leads but if you have an 8 lead more
On Thu, Mar 22, 2018 at 4:53 AM, Tim Iafolla iafollatim@yahoo.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
I'll just add one thing to Chris's excellent explanation: modern stepper drivers have 4 motor output pins (usually labeled A+, A-, B+, and B-), but stepper motors will have 4, 6, or 8 input wires.
If your motor has >4 wires you'll need a multimeter to figure out which of the 4 wires to connect. There are YouTube videos showing how to do this, but basically you're trying to find the 2 pairs of wires with the lowest impedance between them—those are your A and B pairs. The other wires can just be twisted together in impedance-matched pairs.
Tim
Sent from my iPhone
On Mar 21, 2018, at 10:32 PM, Chris Albertson albertson.chris@gmail.com [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
When you work with stepper motors you don't actually interface to the motor. You interface to the driver. The driver connects to both your power supply and to the motor. The driver is so simple you don't need a drawing as there are just two interface pins
1) "step" the leading edge of a pulse will cause the motor to move one "step". typically a about 0.9 degrees or less. These are switches on the drive that set the step size.
2) "direction" this pin is either high (5 volts) or low (grounded) and determines in which way the motor steps CW or CCW.
That's it. two pins. If you want the motor to rotate at 60 RPM then you send step pulses at (say) 400 pulses per second. The motor stops when you send no pulses.
Given that you are using a modern driver, the above is all you need to know.
On Wed, Mar 21, 2018 at 6:26 PM, 'Johannes' johannes@lavoll.no [7x12minilathe] <7x12minilathe@yahoogroups.com> wrote:
Hi Mark
I have worked with 555, but not with stepper motor, can you give us a drawing ?
/johannes
Fra: 7x12minilathe@yahoogroups.com [mailto:7x12minilathe@yahoogroups.com ]
Sendt: 21. mars 2018 10:52
Til: 7x12minilathe@yahoogroups.com
Emne: Re: [7x12minilathe] Re: Mini-Mill CNC, First Test of X-Axis.
RE: pulser for simple stepper control. I made one for zero dollars -- I already had a 555 timer chip, and my electronics scrap box had the perf board, resistors and capacitors I needed to make a simple clock generator. A slide switch allows me to select the direction, and I can adjust the clock rate with a pot.
I used the thing to run a stepper as a low-speed diamond grinder for shaping and sharpening carbide scrapers. I bought a set of 6" diamond lapping disks from a lapidary supply outfit, 150 grit up to 3,000. The low speed keeps everything cool (particularly since I run the bottom portion of the disk through a pool of water). It does a good job for me. I made a simple arbor to mount the disks using my lathe.
The ebay pulse generator looks like a good value if you're not able or willing to DIY one.
Mark
[Non-text portions of this message have been removed]
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Chris Albertson
Redondo Beach, California
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Chris Albertson
Redondo Beach, California
[Non-text portions of this message have been removed]
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Chris Albertson
Redondo Beach, California
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