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Author: Subject: Talk to me about stepper motors
mark chandler

posted on 28/10/18 at 07:33 AM Reply With Quote
Talk to me about stepper motors

I have a couple of things I want to drive, a small milling machine , just one axis really and a rotary table so I can take smooth passes at varying speeds.

Now I can just buy a 25rpm motor and a speed controller which looks pretty simple or use stepper motors, these look complicated, need drivers and stuff.

Googling is not helping me, so please can someone help me out.

A stepper looks a much nicer option but the array of drivers is confusing me, can you suggest a motor, driver, controller and power supply as a package please.

I could then look at both axis on the mill and play with CNC, fir now and probably forever forward, reverse speed and push button stepping is all I need s a box with a few buttons and a speed control.

Cheers

Mark

[Edited on 28/10/18 by mark chandler]

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rf900rush

posted on 28/10/18 at 09:55 AM Reply With Quote
I have had both Steppers and DC motors on my Lathe and CNC steppers on a Mill.

Steppers are best suited for basic CNC.

DC motors would be easiest for just moving.
You could use an old wiper motor/gearbox or may be a old cordless drill

The steppers would need drivers plus some sort of controller to send step and direction to the driver.
Steppers to run smooth, fast and with decent torque starts to get expensive.

There is lots of info out there for CNC conversions.
Free software for hobbyists, go for either turbo CNC (DOS based) or Mach3 (windows XP)
Almost any throw away PC that has a 25way printer port should work.

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v8kid

posted on 28/10/18 at 11:37 AM Reply With Quote
I'm in the process of fitting steppers to a series 1 Bridgeport that has a knackered x drive gearbox but its taking ages......

TBH the most difficult part is the mechanical setup. Electrically you can buy steppers and drivers complete with power supplies as a kit on eBay very reasonably and the software is free for a limited version (mach4 in my case) which you can extend if you want to do more. I have an old PC doing the control linked to a motion controller just for fun

Steppers are very powerful, quite precise, heavy, and the belt drive needs to be robust. For hints look at the Flashcut videos on youtube. They are fiddly to copy as a one off so I ended up designing my own drive based on a collection of other peoples ideas.

One chap you should check out is Mike Hoffman who publishes a free online manual on rebuilding Bridgeport J head mills and in an appendix details his modifications to enable CNC. I used his motor support idea, Flashcuts table mount method and Bridgeports CNC drive belt system to make my hybrid - dunno how well it works tell you when I finish.

I made my controller plug in so I can control various accessories, mill, lathe, rotary table etc.

Started out as a cheap way of replacing a knackered gearbox but ended up quite pricy as I got interested and carried away with myself

Stick to the plan and you can do it under 100 I reckon - unless someone knows otherwise.

Cheers!





You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a chainsaw

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mark chandler

posted on 29/10/18 at 08:12 PM Reply With Quote
Thanks chaps

This then looks interesting

https://www.ebay.co.uk/itm/German-Ship-EU-Free-Nema-23-Stepper-Motor-270oz-in-3A-3-Axis-3D-CNC-Mill-Kit/182604282092?hash=item2a841038ec:g:7mgAAOSwEK9 Ts841

Albeit far more than I need.

Although a lot more than a simple DC motor and speed controller.

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rf900rush

posted on 29/10/18 at 11:07 PM Reply With Quote
I fairly sure Wantaimotor is where I purchased my most recent stepper motors. and they have run in the hundreds of hours now.
But mine where the next size up nema34.

The controller listed look just like the a previous model I had. I worked well on my Warco mill/drill.
Although I blew one up. but they quite cheap on ebay.LINK
Plus they can easily be replace/upgraded.

I doubt you will regret going CNC.
I even bodged together a temporary setup on a lathe to cut some 50mm by 0.5 mm threads.

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v8kid

posted on 30/10/18 at 05:51 AM Reply With Quote
Those steppers are quite low torque and you don't need 3 just to drive one axis. A lot of guys use steppers for 3d printers or plaasma cutters rather than Mills which require more force iirc I used 1600ozin in the Bridgeport. Nema just refers to the size of the mounting flange. Smaller nema tends to have faster acceleration and larger nema more torque





You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a chainsaw

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mark chandler

posted on 2/11/18 at 10:17 PM Reply With Quote
99 got me this

3 PCS Nema 23 Stepper Motors with 270oz-in holding torque,3.0A
1 PC 350W,24VDC power Supply,
1 PC 3 Axis Control Board & 1 Cable,
1 PC Cable

Hopefully I can do something with this lot

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mark chandler

posted on 18/11/18 at 08:36 AM Reply With Quote
All arrived and looking very nice, first stumbling block my laptop will not run anything as no printer port so having to buy as PC to run it, not that bad really as it will give me something to house the 24v power supply and control boards... Still an extra 50

Then the hard work starts, building the motor mounts, machining the drives etc.

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v8kid

posted on 19/11/18 at 02:27 PM Reply With Quote
What software are you intending to use?

I have now completed most of the mechanical setup , and all of the control panel wiring and am at the stage of trying to get the steppers to step.

Using Mach4 free trial can't get a peep out of them. The software is communicating to the smoothstepper but the Wantai free BOB is giving - zilch.

Contemplating replacing the BOB or trying Mach3 and driving the BOB via the printer port.

And I thought the Mech bit was hardest - I've spent longer on software :0

Cheers!





You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a chainsaw

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Oddified

posted on 19/11/18 at 10:22 PM Reply With Quote
Mach3 via a 'real' printer port is about the easiest there is to get working.

Ian

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v8kid

posted on 19/11/18 at 10:59 PM Reply With Quote
I may yet have to try that I've already installed a printer port on the PC via an express port ( or PCI can't recall). Would prefer to use Ethernet as opposed to parallel port as it is more immune to noise.

However I checked the output from the Ethernet smoothstepper and I'm getting output pulses on the x and y axis step and direction but no output from the breakout board. So assuming it's buggered I've ordered a different one (24v ) off the bay. Apparanty this is common with cheap Bob.

Also the free BOB that came with the steppers only requires a 5v power supply and I need 0 to 10v for spindle control - yes I'm trying to justify it 😁.

Cheers





You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a chainsaw

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mark chandler

posted on 6/1/19 at 07:30 PM Reply With Quote
Update on this

My laptop had no printer port so 40 won me a dell Optiplex, loaded it with an old version of 32bit vista and loaded Mach 3.

A few hours wiring it up and finally the steppers start to roll

The motors I purchased are not hugely powerful so I purchased some gears and toothed belts for a 3:1 step down, made up some brackets up and fitted thrust washers on the spindles - it's an old mill (Dore Westbury) with basic acme threads, hardly any slop in these and fitting the thrust washers has made a huge difference, backlash down to a couple of thou on the now on the X & Y axis.

For the Z I have used the original quill drive, removed the fine feed wheel and direct driven a 25:1 step down smaller nema 17 motor.

Today set up the axis using a micrometer, all very close with maybe 1/2mm on full travel so tried a few cuts in ply / not going to break expensive mill bits and waste steel on my first day!

CNC is amazing! Using the Wizards I have cut some circles and drilled multiple holes... I could watch and listen to this working all day long, break out the tape measure and I would never ever spot drill to this accuracy.

If you are thinking about doing this do it!

[Edited on 6/1/19 by mark chandler]

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v8kid

posted on 21/1/19 at 06:31 PM Reply With Quote
I'm impressed with your quick progress! To get this far took me 12 months (with a box of bits restoration)

If anyone else is trying this beware cheap BOB's I traced my woes to them.

Now operating 2 1/2 axis on original acme threads getting 5 thou backlash and repeatable positioning. High speed is slightly disappointing at 100ipm though I'll have to play more with settings

Cant wait to try Wizards

Cheers!





You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a chainsaw

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mark chandler

posted on 21/1/19 at 10:49 PM Reply With Quote
2 steps forward, one back.

Table works fine, the z axis motor is however a fail and it's nothing to do with me...



The motor has smashed it's gearbox, this should have been designed to exceed the torque of the motor, not smash it's teeth to bits in use, I have ordered a low powered nema 23 with a larger gearbox to be safe.

Anyway here's it working away

[youtube]https://youtu.be/Z5UrJNfXF2w[/youtube]

Quite noisy as its nibbling at the steel, it's much quieter with a heavier cut.

[Edited on 21/1/19 by mark chandler]

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