Ridgeback published a new build:

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Very accurate! I measured repeat accuracy down to .01mm. I have a video moving it out 10mm then back again, and then doing to same in .1mm, then .01mm. Works like a charm! I will upload it and post here in a little bit.

 

Here's a video of the accuracy and precision.

 

I posted earlier, I went to .01mm, it appears, and I just double checked on the machine, .001mm movements were made!

 

Thanks guys!

 

Hi w1987,
What portion is failing? Can you get the GRBL prompt on your Adruino? Type $$ to see the config parameters. You don't need the Protoneer board installed to get the prompt. If GRBL is working, pop on the Protoneer board. Make sure the motor drivers are installed correctly. If you are using Pololu's make sure they are rotated as my picture shows. The driver potentiometer should be facing toward the external power connector. Also are you supplying the board with 12VDC? Next up the motor cabling, you need to make sure they are wired into your connector correctly. There are two coils on most Nema17-like steppers. Also make sure the jumpers under the motor drivers are installed correctly. I had this problem. With Pololou 4988's you need all three jumpers installed. The jumpers are installed vertical parallel the long length of the Pololu driver. Protoneer's website has a good picture of this setup for the microstepping jumper. Next up, if all of that is good, then you need to set your step rate in the GRBL $$ command. $110, $111, and $112 are the ones you tweak until your motors move your assembly the correct distance. I moved my x, y and z in 10mm increments until I tweaked the values until it moved exactly 10mm.

Hope this help.
Mark

 

Hmm, reading the above, my gut instinct is motor wiring, but without seeing the setup, I'm unsure. Also are you adjusting the potentiometer until the correct voltage for your motors?

 

Good deal, you lots of spares! Ok so to make sure things are wired correctly. Use an Ohm meter to find your motor pairs. Basically two of the wires will be connected together through a motor coil, and the same for the other pair. Once your find these two pairs, make sure they are wired to the 4 pin connected toward the Protoneer board correctly. According to the schematic, on the right side, the pairs should be wired 1A, 2A, 1B, 2B. So that means, one pair are in the first two holes of the connector, the next pair are in the next two holes. This is my stepper: https://ultimachine.com/content/kysan-1124090-nema-17-stepper-motor
My connector is wired RED, GREEN, YELLOW, BLUE in that order. Then plugged into the Protoneer, with the RED end toward the non-powersupply end of the board. It doesn't really matter as you can simply rotate the connector 180 in case the motor turns the wrong way
But the wiring order should matter I think. Use this as a guide to match up your motor's coil pattern. If one coil is backwards, it may fight the other coil!

PSU wattage is more than adequate. Is it 12VDC?

 

Hey no worries. Hope you get your machine online!
I have one major change. My Z system was reversed so that the motor, motor drive screw, spindle mount and spindle move relative to a stationary screw block. I had to do this because my old system lost vertical clearance with the fatter headed spindles such as the Dewalt. It would hit my motor as it overhung too much. Here is the new X drive assembly. I like it a lot!

 

Thanks. The Z holds very well and is quite stiff. Once I get good and practiced at milling aluminum I'll custom cut new plates to recover my Openbuilds for other projects

I think the 24V 10A psu is more than enough. Since the Z drive barely runs, and the instantaneous current usage will rarely be at full current during a X/Y movement. Typically the highest current will only occur during high stress movements, such as cutting aluminum with a very heavy spindle, and dull cutter. So at 2.5 AMPS and you have three motors going full blast, it's still only 7.5A. Which I doubt is going to happen in most circumstances.

 

Hi Dave,

For the motor controller I use an Arduino NANO loaded with the GRBL firmware and a Protoneer motor shield. The NANO's are literally $3 on Ebay, and the Protoneer is from New Zealand, cost's $20. You have to buy some Pololu A4988 servo controller modules for the Protoneer. This blog posts details everything for it: Arduino CNC Shield – 100% GRBL Compatable | Protoneer.co.nz

Then all of the metal parts, screws, motors, linear rails etc.. were purchased right here from Openpartsbuildstore. Final cost? On the original post here I break it all down: Apple Crate CNC | OpenBuilds
But, I will tell you, if you've never done one of these before, I HIGHLY recommend buying something half built such as the kit they sell here: C-Beam Machine Mechanical Bundle
This version of my Apple Crate has gone though a few revisions and is no longer the same as before. It's now much stiffer, and the Z portion is completely re-engineered and is MUCH more stable. I still have stress induced shearing and bending on tougher materials. Foam is a blast to cut, but messy!
For software, it's all freeware online. CAD I use a community version of Fusion 360. CAM I use jscut.org and finally for driving the CNC with the output from JSCUT I use ChiliPeppr - Hardware Fiddle

Hope this helps and Merry Christmas,
Mark

 

For sure!
The biggest feature change is that my base board no longer drives the Y axis. In other words I now have it firmly bolted to the bottom of the Apple Crate. All of the mechanical movement is now an H frame on top of the Apple Crate. If I wanted to, it would be easy enough to simply unbolt four L brackets then move the entire assembly to another build structure!
Protip: Those nylon wheels are MUCH better than the all steel wheels. Much smoother, and I can squeeze them onto the rails tighter without slop.
Protip #2: I'm not too sold on the springy motor to acme screw couplers, they stretch/compress under stress. I can reduce one direction of compression by crushing the 8mm lock collar on the acme screw up as close to the motor mount as possible. I'm considering putting a lock collar on both sides of the mouting plates for all motors with couplers. Something I will play with

The whole enchilada by Ridgeback posted Dec 25, 2015 at 11:05 AM

Y Axis right side by Ridgeback posted Dec 25, 2015 at 11:05 AM

Z Axis Back by Ridgeback posted Dec 25, 2015 at 11:05 AM

Z Axis front by Ridgeback posted Dec 25, 2015 at 11:05 AM

Z axis up close by Ridgeback posted Dec 25, 2015 at 11:05 AM

Z Axis Front LEft by Ridgeback posted Dec 25, 2015 at 11:05 AM

Left side Y Rail by Ridgeback posted Dec 25, 2015 at 11:05 AM

 

Your very welcome, happy to help!

 

Haha thank you.
The lead screw move so slowly they don't really wobble much at all. But now that I think about it, putting the lead screw mount on the free end with a tight lock collar would trap the lead screw from parallel motion. Duh...I should have thought of that earlier! I guess I now know what I'll be doing the rest of the week lol

 

Ok... So I had just enough parts to rebuild the Z- drive lead screw connection. I added a lock collar and 8mm bearing, on top of the motor mount plate. This lifted the motor coupler up about 3mm, which means my spacers were too short. I simply hacked off of 3mm of the motor arm and everything fit together nicely. Results: TOTALLY AWESOME! Wow what a difference in overall Z lash! I'm going to do this to all of my axis(axii?). I just need four lock collars, and four more 8mm bearings.
As I remove little bits of slop here and there, I find new ones. The next major slop point is the plastic acme nut block. I can slop the Z-drove about 1 full mm up and down in it. Looks like I need a vertical, rotated version of one of these: Anti-Backlash Nut Block for 8mm Metric Acme Lead Screw
I may be able to take a second acme nut block and mount it upside down on top of the existing nut block, then put a solid spacer between one of the nut block screw holes and then run a longer mounting screw through the holes with the spacer in it. The old mounting screw would stay where it is, in the bottom nut block. Then the top nut block, I would mount a bolt and two nuts in it's mounting screw hole and drive it downward as a set screw. Whew.... I'm not sure it would provide anti-backlash in the Z-up direction. Then again, it doesn't hurt to try!

 

For sure, I have to dig into this some more and see what I can do.

Yes, yes it is

 

Here ya go! Lock collar and bearing on both sides of the plate.