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DIY CNC mill from scratch

Posted: Tue Sep 14, 2021 11:27 pm
by WastedFreeTime
Kudos to the Centroid team for making a truly great product! I originally built my C-frame mill from scratch and ran it with LinuxCNC for ~7 years. In the last 6 months I've converted the control system over to use a Centroid Acorn Rev4 with Centroid Mill Pro software and I'm very impressed.
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This is a hobby size machine probably most similar in size to a G0704. It weighs in ~1100lbs with travels X=17.6", Y=7.25", Z=9.8". The structure of the machine is built off a granite surface plate base with linear rails and ballscrews used for all axes. The column is an epoxy granite filled square steel tube. It has both mist and full flood coolant with a washdown hose. It also has a one shot oiler that feeds all 15 oil ports. The spindle is an epoxy granite filled X2 mini mill headstock with R8 taper and sealed angular contact bearings. Current pulley setup makes for a max spindle speed of 5360rpm. I'm currently using the TTS tooling system for fixed length tool holding.

Probing is accomplished with a Renishaw TP2 probe and a Shina SK-66 fixed tool touch off plate mounted to my table. Combined with the handheld MPG and Swissi's fantastic ProbeApp V3, the overall user experience is greatly improved over my previous LinuxCNC setup.

The control system is built around a Centroid Acorn Rev4 which has been very easy to use. Closed loop NEMA 23 steppers from StepperOnline are used on all 3 axes. The Z-axis is off loaded with gas springs and a power off brake is used on the Z ballscrew to make sure it can't backdrive under the weight of the head. The spindle is a repurposed treadmill PMDC motor and associated controller. Its rated for 1.5kW but given that its a treadmill motor I suspect the decimal point is in the wrong place on that power rating. I use a custom brake controller board to short the motor leads across a braking resistor to slow the spindle for faster tool changes. The addition of the PWM spindle control output to Rev4 of the Acorn made it very easy to control this type of spindle.
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Like any good CNC machine, its still making parts of itself to improve the user experience. As of late, its been machining its own Power Draw Bar parts.
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Test fits of the Power Draw bar are going well so it will be up and running soon.
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Re: DIY CNC mill from scratch

Posted: Tue Sep 14, 2021 11:29 pm
by martyscncgarage
Nice work!
Marty

Re: DIY CNC mill from scratch

Posted: Wed Sep 15, 2021 8:03 am
by tblough
Like any good CNC machine, its still making parts of itself to improve the user experience.
Our hobby is a recursive one, isn't it? Making tools to make tools.

Re: DIY CNC mill from scratch

Posted: Thu Sep 16, 2021 10:59 pm
by WastedFreeTime
Fact! Its all about the journey.