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Another Build Thread

7301 Views 73 Replies 6 Participants Last post by  TimPa
I guess I should start this thread by going through my thought process for selecting the type of CNC router I wanted to build. I have a very limited work area in my basement so that was going to be a limiting factor right out of the gate. This is going to be a woodworking tool and later a laser etching & engraver. I love lasers.

The other major factor was budget. CNC routing can get very expensive, very fast! My target budget for this project was 2000 USD.

I have an existing sturdy worktable where I plan to locate the router. Next, what am I going to do with it; basically, small woodworking projects and laser engraving. Therefor I chose to build a machine with 750 x 750 mm footprint which will give me about 22.44” x 20.66” of travel.

The next consideration is what materials will this router be constructed from. Most DIY CNC routers are built using either MDF, aluminum extrusion, or steel. MDF can be easy to work with and cheap to buy and many first time builders use this material. Slotted aluminum extrusion, commonly from a company called 80/20, is used on many DIY CNC router design plans available on the internet. It offers many design options due to the large amount on mounting brackets and configurations the slotted design allows. Aluminum extrusion would also be the most expensive of the three methods I listed. Steel is also used to construct many DIY routers. Square tubing, angle, and flat stock are common and can usually be locally sourced. In most cases steel machines are welded together so a welder and the ability to weld are necessary. Steel is generally going to be less expensive per foot than aluminum extrusion. Unfortunately I don’t have access to a welder and power hacksaw so I am forced to go with the aluminum extrusions even though the cost is higher. :(The OX kits available from Bulkman 3D all use aluminum extrusions and this is the mechanical system we will utilize for the construction of our CNC router.

The OX kit utilizes V-groove bearings. The chamfered slot along the aluminum extrusion is designed to fit standard V-Groove Bearings that are part of a carriage assembly built with a simple Dual Bearing Plate. Bearing pressure is easily adjustable using a wrench and Eccentric Bushing. This seems to me to be a good compromise as opposed to the much more expensive linear rail systems.

One of the keys in making my decision to go with the OX kit was the type of linear drive that it utilizes. The most common on DIY CNC routers are ribbed belts, ACME screws, and ball screws. It seems to me that the main consideration when choosing which system to use is not about how “good” each system is, but what materials you are intending to cut, and what tolerances you will require.

Belts are the cheapest of all solutions, and look increasingly cheaper on longer runs where you would otherwise have to deviate away from standard 8mm leadscrews. All in all, belts are the simplest and cheapest to implement. Belts have the additional advantage that when the motors are powered down, you can move the gantry around by hand. The OX kit utilizes belts for the X and Y axes and a lead screw for the Z-axis since this machine will primarily be a woodworking tool as well as a laser engraver.

All of the OX kits include an option for stepper motors. I chose to include the stepper motor option when I purchased my mechanical kit of parts. The motors are NEMA 23 rated at 345 oz-in torque (2.45 Nm).

Cost: I estimated my cost for the complete machine and electronics around $2000. Here is the breakdown:
Mechanical kit including NEMA 23, 345 oz-in (2.45 Nm) stepper motors: $535.00
Router spindle assembly including VFD, mounting bracket, and W.C.: $265.00
Motor drivers: $100.00
Controllers & Misc. Electronics: $400.00
Miscellaneous tooling: $200.00
Software: $275.00
Total Project: $2000.00

I suspect that I will end up going over budget given the cost of tooling and software, but that is down the road. I will try to post to this thread on a weekly basis as we go through the selection process for the stepper drivers, controller and spindle, as well as getting into the wiring of this machine tool.


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Hope everyone had an enjoyable Christmas holiday! Time to get back to the build.

Spindle Mounting Issues

As you may remember from one of my earlier posts (#20 & #23), the spindle I purchased came with a mounting bracket, and quite a mounting bracket it is! Weighing in at over 2 pounds this is an impressive hunk of metal. However, try as I might, and in consultation with some other knowledgeable folks it was determined that this mount would not work out for my build. So, I searched the net and found what I considered a suitable replacement and ordered it. Here is a pic of the bracket that came with the spindle:

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The new bracket arrived this past week. Unfortunately, using this new bracket is not going to be as straightforward as I anticipated. The biggest obstacle is the interference with the roller mounting screws. These screws protrude past the rollers and lock nuts 3.7 mm and interfere with anything bolted to the Z-axis 2060 that extends past the 60 mm footprint.

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If I shortened the roller attachments crews from 65 mm to 60 mm there would not be sufficient penetration into the lock nut.

I had purchased a 12” square of 3/16” (4.7 mm) Type 6061 aluminum plate which I was going to use in order to fabricate an adapter to use with the original spindle mounting bracket. As I mentioned previously, the screws protrude 3.7 mm past the lock nut. By attaching the new mounting bracket to a spacer plate fabricated from the 3/16” stock we can achieve 1 mm clearance between the new spindle mounting bracket and the protruding roller mounting screws.

Now 1 mm is not very much, so I plan to place a 1mm washer under the head of each roller mounting screw. There is plenty of clearance in back of the mounting plate to facilitate this. The result will be to reduce the protrusion to 2.7 mm, and provide clearance of 2 mm between the screws and the spindle mounting bracket. Or…………

I can simply take out my Dremel, attach a cutoff wheel, and cut the bolt protrusion flush with the nut. Always a very good possibility.

Here is a drawing of the spacer I intend to use sandwiched between the Z-axis 2060 rail and the spindle mounting bracket. Notice that the spindle mounting bracket and spacer are attached to the Z-axis rail with the 5 mm dia. screws.

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Finally, there is one other issue that needs to be addressed. The Z-axis rail in my router is 60 mm wide. The new spindle mounting bracket that I just purchased can be used for both 60 mm wide and 80 mm wide rails, but……….

When you bolt on the right angle corner brackets using the 60 mm mounting holes, the corner brackets protrude into the spindle opening. I will have to grind or mill off a portion of the corner bracket in order to fit the spindle into the bracket opening.

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As it turned out, I spent about 15 minutes with a half-round bastard file and the spindle slipped right into the hole.

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Re-engineering at its finest. Good job.
Woo! Yoo!

I have my DB25 cable from the controller to the main electrical cabinet checked out and no problems.

Next, I made up a 4-conductor cable to go from the main electrical panel to each individual stepper motor. Now for the moment of truth.:rolleyes:

I connected the X-axis cable to the X-axis motor using a 4-position terminal strip. I powered up the main electrical cabinet, reset the hand held controller, set the mode to MPG and rotated the MPG wheel. Yeah! The X-axis motor moves. I then changed modes to step and the X-axis motor moved one step each time I pressed the controller button. Finally I switched the mode to CONT and pressed the X- axis button and the motor ran as long as I kept the button pressed. Worked in the opposite direction as well.

I repeated the process with the Z-axis. Here I had to be a bit careful because I only had about 1/2" of travel due to the bloody screws sticking out. (See my previous post). Yet again I experienced great results in all three modes.

Moving on to the Y-axis, I repeated the same procedure, only this time there was no movement of the Y-axis motors. Time for some troubleshooting, but not tonight. I am dead tired after fighting with lasers all day. Should not be a difficult problem to solve.

By the way, is it possible to post videos?

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By the way, is it possible to post videos?
If they're hosted on a site like YouTube. Widescreen videos preferred over portrait video, btw.
that is great progress, you gotta love it when things move, correctly!
remember to terminate and ground the shields at the controller box end, and not at the other end. if you already knew that, sorry.
thanks for posting your build.
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remember to terminate and ground the shields at the controller box end, and not at the other end. if you already knew that, sorry.
Not a thing wrong with some sage advice! Better to remind everyone, whether you know or not to prevent future mishaps. Should it happen eventually... well you'll learn a lesson.

Looking forward to the video AlbertZ

When you going to take orders :geek:
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Hope everyone had an enjoyable, healthy and safe New Year Holiday.

With that being said, let's get back to the business of building a CNC router. Recall from my previous post that I had the X-axis and Z-axis working in all three modes.
  • Continuous
  • Pulse
  • MPG
However, the Y-axis motors would not operate in either of the three modes.

I have a handy little DMM that has the capability to display waveforms (what wont they think of next?). I checked the pulse output for the X and Z axes and sure enough I got a pulse waveform. I was lokking for something resembling a square wave or trapezoidal pulse, but hey, as the paramedic said, "I got a pulse".

Ah, but there is no pulse signal on the Y-axis when measured at the terminal board. I checked the Y-axis pulse terminal in the RMHV3.1 controller, and the controller was doing its thing generating a pulse. I checked the continuity all the way back to the terminal board in the main electrical cabinet. That is where I was losing my signal!

I pulled the wire out of the terminal block and checked for pulse. Yes! It's there!

All of the signal wires going into the terminal distribution blocks are 22 AWG. 22 AWG is the threshold for reliable contact.

My solution was to put ferrules on all of the signal leads going into the terminal distribution blocks. I now have control of all three axes through the RMHV3.1 controller. :giggle:

Meanwhile other things are happening with spindle mount modifications which I will detail in a subsequent post.

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Been under the weather the past few days – just wanted to stay in bed, stay warm and sleep. Finally got back to the shop last night and got some mechanical work done and a bit of wiring in the electrical cabinet.

Recall back in Post #41 I discussed some of the spindle mounting issues that I was experiencing. Basically, the new spindle mounting bracket that I had purchased was hitting the roller mounting screws. What I needed was an adapter plate in order to mount the spindle mounting bracket to the Z-axis rail.

I procured a piece of 3/16: aluminum plate and cut out an adapter on an Axiom Auto Route Pro+ B18 using Vectric 2D software. I got the part home and found out I had a problem. The spacing of the gaps in the Z-axis rail are 40 mm center-to-center. I assumed the spacing of the holes on the right-angle mounting brackets would also be 40 mm center-to-center. Wrong! The holes were 42 mm center-to-center and resulted in the screws hitting the sides of the mounting holes.

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Rather than bastardize the mounting bracket, I trudged back to our maker space and cut a new adapter plate with the correct hole spacing and I made the plate a bit shorter and narrower. The holes for mounting the spindle bracket were drilled and tapped for M5 screws. The three holes at the top and bottom of the plate were drilled to 5.5 mm. Then I got sick.

After regaining my strength, I went down to the shop and attached the spindle mounting bracket to the adapter plate using four M5 x 10 mm screws. Then this sub-assembly was attached to the Z-axis rail using six M5 x 10 mm screws. Finally, I inserted the spindle into the mounting bracket and tightened it down. I didn’t take time to get everything perfectly plumb because I was anxious to see how the NEMA 23 stepper motor would handle the load. I energized the electrical cabinet and ran the spindle up and down using the controller and the MGP. The motor handled the load without breaking a sweat. Everything looks good except those screws are only 1 mm away from the mounting plate as you can see in the photos.

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I was on a roll so I decided to install the pulleys on the Y-axis and X-axis motors and proceed with the GT3 belt installation. It was here that I ran into another problem. The GT3 belt is secured at each end of the rail sliding the belt under a T-nut and clamping down with a 5 mm screw. This assumes that you have room under the T-nut to slide in the belt. This only works if you have flat T-nuts. I prefer to use machined T-nuts which have more thread and provide more secure attachment when mounting to the rails. However, they don’t work so well when you want to use them to clamp down the ends of the timing belt. I ordered some flat T-nuts from McMaster Carr which will be delivered on Tuesday. That will finish up the mechanical assembly.
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I mis-spoke! I ordered the flat T-nuts from Amazon and they were delivered today!

I installed and secured the timing belt on the X-axis and gave it a quick test. The motor missed steps and stalled if I kept pressing the button. Not good. I went into the controller and found that the pulses per unit was set at 1260. I kept backing that down until the speed was roughly where I wanted it and the motor was running smooth. I set it at 80 pulses per unit and did the same for the Y-axis. I set the Z-axis to 320 pulses per unit and that gives just about the right speed. Later when everything is assembled, I will calibrate the axes and set these parameters so that they are spot on.

Tomorrow I will enlist the aid of my grandson and try to shoot some video of everything in motion.

Below is a shot of the waveform on the X-axis with the pulses per unit set at 1260. Note that each increment on the horizontal (time) axis is 5 microseconds.
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The next picture shows the waveform with the pulse per unit set at 80. We have a nice clean square wave with just a bit of noise superimposed. That should clean up when I finish wiring up all the grounds.

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I am a very happy camper! :giggle:

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Just a quick update this evening............

I had used 4-pin aircraft connectors to run cable to the stepper motors. What I completely overlooked was how to tie the shields to ground back at the electrical panel. I could have run an external wire tied to the shield back into the panel, but that would have looked like crap, although electrically feasible. Instead, I ordered some 5-pin connectors, and I am in the process of converting from 4-pin to 5-pin and bringing the grounds inside the cabinet in this manner.

Meanwhile I ordered some limit switches with integral switch bounce elimination circuitry. Trying to figure out how to mount them.

Finally, it occurred to me that in my last post I kept referencing a specific page in my controller that most of you would have no idea what I was talking about. So here is a pic of the specific page where you can set up the motor parameters.

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Meanwhile, I am trying to figure out what post-processor this controller uses that is compatible with Vectric V-carve.
I would like to shoot a video with the machine actually executing a profile without the spindle and bit.

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Meanwhile I ordered some limit switches with integral switch bounce elimination circuitry. Trying to figure out how to mount them.
not sure which type you ordered, but you want to mount them such that if the switch/circuitry were to fail, the switch does not get smashed. seen it happen too many times, bad design.

its great to see the use of an oscope. had one tied to my hip for 19 years. looking for a used 2 channel, have to recap an old stereo receiver. that 1052 looks nice...
Finished installing the timing belts and exchanged the 4-pin motor connectors for 5-pin motor connectors. Time to see if we can start moving things using the RMHV3.3 controller.

You can see the results here:

CNC Router Stepper Motor Test - YouTube
I feel like Jethro Bodine after he finished repairing a car. He was left wondering why he had all these extra parts left over. It turns out that I had two X-shaped pieces left over and couldn't seem to figure out what they were for. I'm not sure if I mentioned this, but the kit did NOT come with instructions nor was there one available online. However, I did find a set of instructions online for the OX router and that is what I used. Unfortunately, nowhere was the installation of the X-pieces mentioned.

I went back to the vendor from whom I purchased the kit and perused photos of the finished builds. That is how I figured out the purpose for these parts. They are to reinforce the gantry assembly and take the cantilever load off of the rollers. This allows the load on the rollers to be distributed evenly.

Starting with one side I removed the nuts securing the rollers. Then, keeping pressure on the bearing assembly, I removed the shorter screw and inserted a longer 45 mm screw. Then I slipped a 6 mm spacer over the longer screw. I did this for all seven rollers. Then I slipped the X-piece over the screws and replaced the locking nuts. I repeated the process for the other side. The result is that it stiffened up the gantry considerably. The only slop remaining in the entire assembly is in the Z-axis. I'll discuss this in a subsequent post.

The attached photos will give you a pretty good idea of what I am talking about here.

Does anyone remember "The Beverly Hillbillies"

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It's about time I checked out the spindle operation. But before I get into that, let's review the power distribution on my build. First, we look at the 110 VAC power distribution. The wiring schema is shown below:
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You will see that power supply PS3 energizes a contactor coil located on the VFD panel. So, when the 110 VAC is switched on the contactor energizes and the 220 VAC to the VFD is also switched on.

Next, here is the wiring schema for the 220 VAC panel. Without wiring the interface to the RMHV3.1 controller, we should be able to manually operate the spindle.
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Here is a photo of the 220 VAC panel:
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The connection to the spindle motor is at the far right side of the panel (nothing plugged in yet).

After carefully checking all the wiring connections, I hooked up everything except the signal wires to the RMHV3.1 controller. I wanted to see if I could manually control the speed of the spindle motor.

You can see the results on this U-tube video.

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Looking for Some Input from Those Following This Thread

After making the adapter plate for the spindle mount, I am still not satisfied with the robustness of the entire assembly. Clearly the spindle mounting arrangement was intended for a much smaller spindle than the one I have chosen. I am concerned with the overall machine height. Without doing a FEA, it is clear that the possibility of induced harmonic vibration exists. I would like to relocate the Z-axis stepper motor to reduce the overall height of the assembly..

I am not happy with the design wherein the Z-axis rail moves up and down with the spindle. Also, the 2060 aluminum extrusion rail is relatively puny. I would prefer to see a more robust support for the spindle mount.

I have been puzzling over where to mount the home and end of travel limit switches. Since the rail moves with the spindle, I would have to fabricate a pair of brackets that attach to the X-axis rails. They would be prone to damage and would further restrict the X-axis travel.

I have been considering a possible upgrade for the OX CNC Router using C-Beam aluminum extrusion. The C-Beam (4080) would form the Z-axis rail and the length would be increased to 330 mm instead of the existing 200 mm. This would permit approximately six inches of travel instead of the current three inches. The C-Beam would be fixed and would bolt to the X-axis carriage assembly. The Z-axis motor would be mounted behind the C-Beam and power transmitted to the lead screw via a timing belt.


  • Lower overall machine height
  • Lower center of gravity - less vibrations
  • Easier to reach Z axis to manually turn (versus reaching in between motor and C-Beam in the conventional setup) for manually adjusting Z Zero
  • Increase the travel distance to six inches
  • Future: Reduction Drive (Pulley ratios) for even more torque
  • Provide a place for mounting the limit switches since the rail is fixed and does not move up and down.

  • More parts
  • Cost: At least another $100
  • Probably be required to disassemble the entire X-axis assembly
  • Time: Lost time when I could be getting ready to make things.
I will need to order some additional parts:

  • 1 x 500 mm long C-Beam (to be cut down to 330 mm)
  • 1 x Double Wide Gantry Plate
  • 1 x 500 mm long 8 mm Acme lead screw (to be cut down to ~330 mm)
  • 1 x C-Beam End Mount
  • 1 x NEMA 23 Reduction / Stand Off Plate
  • 1 x 3GT (GT2-3M) Timing Pulley - 20 Tooth - 9mm Belt - .25" Bore
  • 1 x 3GT (GT2-3M) Timing Pulley - 20 Tooth - 9mm Belt - 8mm Clamp Bore
  • 1 x 3GT (GT2-3M) 9mm Timing Belt - Closed Loop
Since I have not carved my first piece of wood, it is quite possible that the existing Z-axis assembly will work quite well. Or I may be rather disappointed which would lead to discouragement. Should I bite the bullet now? Or should I take a chance and see how things work out. I am interested in your opinion. What would you do if you were in my shoes?

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Cannot help you with that one, Albert.

Not a CNC user, just following the thread to see how it works out for you....

IMO, since you have invested so much time, effort and money, I would continue to, at least, a testing stage.....
@Albert Z you got this far... please continue. Once done post another video w/ first cut. ditto @jw2170

Nice that you're detailed w/ description as baffling as it is to me that I wished I would have taken the time to learn
the electronics stuff. Oh well.

Being discouraged doesn't happen here and there are no bullets for biting, so you'll have to continue.

Take the chance, we're in your shoes now. ;)
Z-Axis Upgrade

After careful consideration, I decided to go ahead and order parts for the Z-axis upgrade. Here is the way I see it: I want more Z-axis travel and I need a method for mounting the home as well as the end-of-travel limit switches. If the upgrade would have cost several hundred dollars, I might have settled for the existing configuration, but the total cost for upgrade parts will be around $100. A considerable sum to be sure on my limited budget, but doable.

Limit Switch Configuration

Speaking of limit switches, I finally decided that I would use Hall effect sensors. For those not familiar with Hall Effect sensors, they are a type of proximity switch, but they are triggered by a magnet. A major downside to using Hall Effect switches if you are machining ferrous materials is that the magnets tend to accumulate metal filings.

The biggest advantage is that there are no mechanical parts to wear out. They are extremely reliable and completely electronic.

Here is the switch I will be purchasing:
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And here are the specifications:
  • Type: NJK - 5002C
  • Mounting: M12 cylinder
  • Output: NPN open collector, three wire, normally open
  • The detection distance: 10 mm
  • Supply voltage: 5-30VDC
  • Output current: 150 mA
  • Detected objects: permanent magnets
  • Switching frequency: 320 KHZ
  • Wiring: brown-positive, blue-negative, black-signal
My RMHV3.1 controller has an internal 12-volt bus used specifically for external limit switches and Z-axis probe. So, the controller will integrate very nicely with the Hall Effect limit switches.

Two 4-conductor cables will connect the RMHV3.1 with the limit switches. One cable will have the signals for the Home limit switches and the +12 VDC. The other cable will have the signals for the End-of-Travel limit switches and the corresponding ground. These cables will terminate to a 12-position terminal strip located close to the router base. A 3-conductor cable will connect each limit switch to the terminal strip as depicted in the wiring schema shown below:

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An Update on Progress

Z-axis Rebuild

All the parts are on order. My grandson and I are doing the 3D CAD drawings using Onshape cloud-based software. I expect the parts to be here in about two weeks. China Express.


The supporting table is not level and is not supported on all four legs. I've got it stabilized with wedges but looking for a better solution.


Got the VFD panel installed inside the supporting table. Need to make a couple of changes to the wiring in the main electrical cabinet but gave away my wire to the robotics club I am mentoring. After making the changes, I will mount the electrical cabinet in its permanent spot on the supporting table.

Limit Switches

I am super excited about using the Hall Effect limit switches. I tested them on the work bench, and they work flawlessly. Depending on the size of the magnet I use, the trigger range is either 5mm or 10mm. The sensors I am using are NJK-5002C. Attached are photos of one of the sensors installed on the Y-axis.

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TimPa suggested that it may be safer for the limit switch to be mounted on the side of the plate rather than in front of it. In case of a crash the limit switch would not be damaged. Another advantage is that I can epoxy a magnet to the side of the plate instead of fabricating and mounting a separate magnet holder.

After dinner this evening I quickly cobbled together a mount for the limit switch which faces the side of the plate. I love it!

Thanks Tim

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