Fully supported linear bearings - Radial squareness

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Originally Posted by Slixxor

The bed size is 1300x1000. I am happy to run whatever I need in order to be able to mill aluminium comfortably. I opted for the 34's due their torque at low rpm. Can anyone suggest a nema23 suitable for the application, they certainly are cheaper :)

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nema 34 is overkill and won't work as expected try these https://www.cnc4you.co.uk/Stepper-Mo...YGH301B-Nema23 more than capable for that size of machine

Thanks Clive S,

you've saved me $420 AU. Does anyone else agree with Nema23 23HS45-3504S being the best choice for a steel gantry and Z axis?
that will likely weigh over 30kg?

I'm using these in a slightly larger machine, steel gantry probably weighs around 50kg, and I'm not expecting any problems. It's a very common setup. You do need to drive them with a suitable voltage - 60V or more.

Agree with 23's .. ball screws = 10 mm is ok (5mm better axial load deflection needs looking at )
I assume you are in Aust, so these links might be of assistance. Both are in Melb.
http://www.homanndesigns.com/
http://stores.ebay.com.au/CNC-AND-CU...=p4634.c0.m322
CHECK THE SCREW LENGTH This guy normally lists travel length ..

Paul

Thanks @Paul3112, saved in favourites. :)

This is the kit I ordered but had modified for my lengths: http://www.ebay.com.au/itm/331320314...%3AMEBIDX%3AIT

This is the motor kit I wanted to buy: http://www.ebay.com.au/itm/171994192...84.m1436.l2649
This is the motor kit I am considering now: http://www.ebay.com.au/itm/171937212...84.m1436.l2649

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Originally Posted by Slixxor

This is the motor kit I am considering now: http://www.ebay.com.au/itm/171937212...84.m1436.l2649

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Kits are hardly ever a good idea as they are never matched. You need motors with very low inductance and drives that can handle 68V volts to get the best out of them. Go for a toroidal type power supply rather than a switch mode type.

Before you start spending hard earned cash it might be better to do some research as these parts can make all the difference between a good machine and a duff.

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Originally Posted by Clive S

Kits are hardly ever a good idea as they are never matched. You need motors with very low inductance and drives that can handle 68V volts to get the best out of them. Go for a toroidal type power supply rather than a switch mode type.

Before you start spending hard earned cash it might be better to do some research as these parts can make all the difference between a good machine and a duff.

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Thanks Clive, I dont have an issue with switchmode PSU's. As a worst case i'll make a quick back EMF circuit and put some filtering caps across the bridge.

You are dead right about the affect of inductance on supply voltage, especially at higher RPMs. So I have found a reasonably priced torquey Nema23 model

http://www.ebay.com.au/itm/3PCS-3Nm-...EAAOSw37tV85jU

inductance is 3.8mH - The lowest i've seen on ebay in that size.

What is everyones thought on this motor?

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Originally Posted by Slixxor

Thanks Clive, I dont have an issue with switchmode PSU's. As a worst case i'll make a quick back EMF circuit and put some filtering caps across the bridge.

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Not quite sure whether you mean you'll use a switch-mode supply or not. However, the linear supply is often better to drive steppers; the duty cycle of the load is relatively low, even though the peak demand can be high. With a SMPS, you need to rate it for max peak load to avoid it going into current-limiting where a linear supply can handle the peaks even if rated for average load. But then, you can buy cheap SMPS from China...

My 1000x700 build uses Mema 23 425oz 3amp at around £20 each, and they plenty of torque and speed, forgot to change DOC other day set to 3mm 6mm 2 flute for MDF (cuts MDF 6mm 2 flute at 15mm DOC Regularly), so ended up slot cutting 5083 aluminium at 3mm DOC 6mm 2 flute 1000mmpm FR, stepper torque was not a problem and it cut without incident but was working harder than it would normally.