The steppers on the 3 axis positioning stage shown here [bodgeitquicktools.blogspot.com] needed a lot more umph to move at a reasonable speed. At the modelenginering exhibition it was empasized running your steppers controllers at maximum voltage provides the best speed on the steppers.

Rumaging in my shed I found an old 24V swich mode PSU to experiment with.
I adjusted the PSU to maximum output V = 29V.

Built a small PC using a Gigabyte atom ITX MB with printer port.
I replaced the stepper PC PSU with the now 29V for the 3 Stepper driver boards v2.3.

Stripped down and cleaned the 3 Axis stage oiled and rebuilt it.

I checked the voltages and the steppers. installed Ubunto V8 EMC2.
Spent a while setting up the EMC2.
Then discoverd that the resolution details on the stage are metric not english details.
Thus X & Y resolution of 0.00125 mm and Z resolutin of 0.0001 mm.

The result of this experiment has given me the ability to run the X/Y and Z stages 3 times faster than it could run using a 12V supply.

The Gen3 Stepper driver board v2.3 are Great little boards thank you Zack.

I will get arround to updating my various Blogs on these projects when Im not so busy trying to finsh decorating to rent my partners house and setting up solar powerd workshops at my house for our new buinesses.
I have loads of bits to photograph for the Blogs but running out of time most days at the moment.

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Bodge It [reprap.org]
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What's the heat disipation in the motors like with the voltage up that high ?

I have provision in my circuit board to run to the L298 maximum, I'm still working on my wave forms at the moment though.

I set the Gen 3 Controllers up to limit the current to 0.4A i.e 0.80V on the Vref pin. The hae been turned on and running for 2-3 hours or more at a time the heat is hand warm i.e not too hot to hold. I am using EMC2 and have not figured out how to make use of the Gen 3 Enable Pi so I have all 3 tied Low Thus Steppers are continusly powerd. You must remember Thou:-

The steppers are a little bit short of a full specification like we have with modern off the shelf steppers. They have on the Label 12V 0.4A 1.8 The make is Time and Precision Ltd. My Inet research showed Time and Precison had a technical review online about their Steppers using ground breaking technology. that was all I found apart from them going bust in the mid 90's.

My current problem is the z Axis home micro switch has too much variation on is switching position for EMC2 to accept the home location. I get a home error message. The Microswitch used is the roller on a spring arm type hidden in the Aluminum block the switch point varies in is trip position by +/- 0.800 that is two complete revolutions as a full step is steps at 0.001 mm

The Z stepper has a 20 tooth pully driving a 50 tooth pully atached to a 1mm pitch stainless steel threaded shaft. I re-milled the Aluminum tab to reduce the lenth of its Chamfer for the roller from 4mm to 2mm this made no diffrence to the microswitch hysterisis though. :-(
I am trying to figure out how to fit an opto switch inside the Z housing.

Once I fix this I will be able to mill my Acrilic blocks for my extruder drives.

On my modern stepers using Gen 2 controlers (297 298) I have had to use the enable pin to prevent over heating as the stepers did hit 70c when left on.

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Bodge It [reprap.org]
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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

Thanks for the info Bodge it.

I have quite a variety of stepper motors I've salvaged from old printers over the years. No idea what the rated current is on most of them !

I have from 0.9 degree per step, up to 7.5 degrees per step.

Have you found the lower step size useful in any of your work ?


Regarding your Z axis hysteresis, I suggest in the mean time, before upgrading to optical interrupter, you could set up the microswitch with a shorter lever length to the fulcrum, and thereby reduce the hysteresis amount by the same ratio as the shortening of the arm. A thick piece of solid rubber on the arm's contact point could prevent damage with overruns.

Thank you for the sugestion on the micro-switch.
Its made me think about removing the micro-switch with the roller on the end of the Arm an putting a non rollerd micro-switch in instead which could then be shortend.

This project is my first one using a higher presision stage movement.

I saw the xyz stage at the Model enginering exhibition in Harogate offerd £40 then bought the Micro Mill to go with it..

I used the Mill with one of axis held in a vice to re-cut the miscro switch tab chamfer.

I'm investigating higher resolution microstepping controllers.
I am designing a 5' x 3' CNC machine for the 5' axis I've bought 2 5ft Sash cramps to use as the X rails for the gantry. This will be driven by belts or chain.
For the Z axis I have bought an 8" wood vice that I have disasembled and reversed the closing jaw to mount the cutting tool on. This will be fixed to the Y axis gantry some how using skate beaings on Alu or steel angle iorn driven by threaded rod or belts.

The X axis drive I will experiment with a bike chain drive at first as its so much cheaper than belt drive. I have 2 x 220NC steppers from Arc Eurotrade and 3 4.2A microstepping controllers that boast of 32k steps per revolution. I will series wire the steppers. I'm currently looking for 3 afordable 50V 10A supplies.

Edited 1 time(s). Last edit at 05/28/2009 03:19PM by BodgeIt.

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Bodge It [reprap.org]
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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

3 x 50V @ 10A = 1.5kW, wow that is some power!

When you use a chopper drive the average current goes down as you increase the voltage. For example, if you drive 5V 3A motors from 50V the PSU current will only be 2 x 3A * 5V / 50V = 0.6A. The peak current will be 6A but the duty cycle will only 1 in 10 so it averages to 0.6A.

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[www.hydraraptor.blogspot.com]

Blushes slightly I may have called my self Bodge It I guess I believe in Belts and braces.. "Theres nothing better than a stiff power source" an ex-boss of mine once said, when we were working on the Dungeness B Coarse group 3 rod control.

I am looking at switch mode supplies so the 10A would be the peak current with the idea of having the higher power ablity in reserve incase I need to have the 4.2A 360Ncm steppers to drive the machine instead of the 220Ncm.

There is also a slight problem with the controllers when in microstepping mode the power enable input is disabled so stopping on a full step I think would require the higher curent.

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Bodge It [reprap.org]
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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]

When micro stepping, the full step position is only 70% on each coil so I suppose the current varies between 100% and 140% depending on where the motor stops. But you still get the reduced duty cycle in the ratio of the motor voltage to supply voltage.

The chopping frequency is relatively high, so you only need a moderate sized capacitor to smooth the PSU current so that it only needs provide the average current, not the peak.

Having said that, if you can afford them then no problem and you could trade up to 500W motors. Plenty of scope for a big bang if things go pear shaped!

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[www.hydraraptor.blogspot.com]

Hmm the Big Bang Theory..

I have just located 50.5V switch mode Power supplies £12 on ebay, the original price £280 so have taken the plunge. Delivery is a bit steep at £28 but dont fancy driving to Slough as if I remember correct its a bit like Milton Keynes with a roundabout or 3 on every road.

If you feel the earth shake up there you will know the Big bang happened.

Just think what could be printed using a 5' by 3' print bed!

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Bodge It [reprap.org]
=======================================

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BIQ Sanguinololu SD LCD board	BIQ Stepcon	BIQ Opto Endstop
BIQ Heater Block PCB	BIQ Extruder Peek clamp replacement	BIQ Huxley Seedling
BIQ Sanguinololu mounting	BIQ standalone Sanguinololu or Ramps mounting	Print It Stick It Cut it

My rep strap: [repstrapbertha.blogspot.com]

Buy the bits from B&Q pipestrap [diyrepstrap.blogspot.com]
How to Build a Darwin without any Rep Rap Parts [repstrapdarwin.blogspot.com]
Web Site [www.takeaway3dtech.com]