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Discussion Starter · #1 · (Edited)
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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David - Machinist in wood
4,512 Posts
Looking forward to the build, Albert. Just a tip on writing up your description, though - add some carriage returns to make this easier to read.

Take lots of photos and share with us; we're ready for the build! :)

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David - Machinist in wood
4,512 Posts
Thanks for the feedback! After I posted I noticed it seemed kinda scrunched up.
You can still edit it if you'd like to go back and fix it. We're ready for photos of the build! Mine was about 5 years ago and is here if you'd like to see my build.

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Discussion Starter · #6 ·
Infrastructure Weekend

Before we can get started with this build, I need a sturdy place to mount the router and I need power. That was my focus this weekend. I have an old Sears workbench (anybody remember Sears?) that is made primarily of sheet metal, but has a very heavy top deck. I'm not sure what the deck is made of, but it is heavy and 1-5/8" thick. The deck measures 24" x 72". I have been using it to collect "stuff". Now it will be re-purposed as my router stand.

The top deck is not secured to the frame so I removed it to see how sturdy the frame was. It felt a little wobbly so I added a 2' x 4' piece of plywood to the back which stiffened it up considerably. The plywood will also serve as a place where i can attach power panels, etc.

The router will require 110 VAC power as well as 220 VAC power. The 110 VAC is already available on a 20 amp circuit. We used to have a swimming pool out back when the grandkids were little but it is long since been dismantled. I had a 20 amp 110 VAC circuit dedicated for the pump and filter so I re-routed the wiring back into the shop and installed a 220 VAC outlet next to the existing 110 VAC outlet. Then I removed the 20 amp single pole breaker and installed a double pole breaker to give me 220 volts at the outlet. There will only be 2 cables going to the wall. All the rest of the electrics will be on the stand or machine.

The router itself will be attached to a sheet of 3/4" plywood measuring 48" x 31-1/2". This will all get fastened to the top deck described above. The attached pictures give you an idea of what we accomplished this weekend.

CNC Router Specs

Here are the specs that I am using for the router build:
  • Travel: X-Axis 22.44” (570 mm)
  • Y-Axis 30.5” (775 mm)
  • Z-Axis 4” (100 mm)
  • Linear Guide: V-Groove Bearings
  • Linear Drive: GT-3 Timing Belt
  • Linear Drive Z-Axis: ACME Lead Screw
  • Drive Motors: 345oz-in (2.45 Nm) NEMA 23 Stepper Motors with DM542T drivers
  • Controller: RMH v3.1
  • Construction: V-Slot aluminum extrusions – 2040, 2060, 2080
  • Spindle: Vevor 1.5 kW, VFD, 220 volt, 24,000 RPM
  • Rapid Speed: 200 ipm (inches per minute)
  • Cutting Speed: 1/4" end mill, full width cut, 0.100" depth of cut, 50 ipm, material - hardwood (This is a fairly easy cut and is probably less than half the true cutting capacity)
Previews of coming attractions

My next posts are going to cover spindle selection, stepper driver selection, and most important - controller selection. Then we can start wiring this puppy. Stay tuned.

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Welcome to the forum.

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Discussion Starter · #8 ·
Stepper Motor Driver Selection

As I mentioned at the start of this thread, I wanted to provide some insight as to why I chose the various components to build the CNC router. I am also trying to get caught up to the point where I can report on current activities. So let's get through the background info starting with the stepper motor drivers.

I confined my search to stand alone units only. I saw some packages that incorporated four drivers in the same package. I believe for ease of troubleshooting and repair that stand alone units are best. But, my O' my, what a bewildering array to choose from.

My intent was to evaluate three different drivers from three different price ranges in a side by side comparison. In addition, this would give me a chance to test the NEMA 23 motors that came with the OX mechanical kit.

The three drivers I chose to evaluate were:
  • TB6600 rated @ 4 amps from Amazon for $10.99
  • DM542T rated at 4.2 amps from Amazon for $28.99
  • Gecko rated @ 6.0 amps for $100.46
The pedigree for the Gecko drivers speaks for itself and I was not going to spend a hundred bucks just to run a test. If the lower priced drivers failed to do the job, then I would consider the Geckos.

These drivers work better with linear unregulated power supplies (like a simple transformer/bridge rectifier/filter) than with a switching power supply, because a switching supply will limit the availability of power when it's needed most, at the instant the motor starts to move.

My test setup is a 36V 10A homebrew power supply, an Arduino to provide a step pulse input which ramps up slowly from zero to establish the maximum running speed, the driver, and the 4 NEMA 23 motors supplied with the OX kit. No shielding or filtering was used, because I wanted to see how good the shielding and filtering is inside the driver under adverse conditions. Peak current for my motors is 3.0 amps so I selected 2.84 amps via the DIP switches on the driver. The documentation indicates that this is the peak current setting and that the RMS current value is considerably less, so I may be able to coax more torque out of these motors once everything is set up and running. I also tried various microstep settings from 2 through 128.

Using the Arduino configuration I was able to ramp the speed of the motors up and down and reverse direction with a button push. The Arduino setup is shown in the accompanying diagram. I will post the code if anyone is interested.

Motors connected to the TB6600 driver skipped steps and made alarmingly loud grinding noises, even when standing still. Not one of the motors performed adequately at any RPM. When I dropped the DM542T into the same setup, ALL of my motors worked fine, with no noise or skipped steps, produced boatloads of torque, and ran cool and quiet.

Stepping motors should not be noisy. Listen to a quality 3D printer and decide if it sounds more like a flute, or more like a bunch of gravel pouring out of a dump truck. If it's the latter, it's almost certainly because the driver is poorly designed. All that extra noise is power being converted into heat and noise instead of useful work.

I ordered three more DM542Ts for my CNC setup and tossed the TB6600 right in the recycling bin. You can spend a lot more on something like a geckodrive but you won't see a boost in performance commensurate with the 300%-500% price increase, unless you have very specific torque or voltage requirements.

The next step will be to test the drivers and stepper motors with the master controller. So I mounted everything on a breadboard and am waiting to finish wiring the controller so I can test the operation of everything before it goes on the router.
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Discussion Starter · #9 ·
Infrastructure Redux

Yesterday I received my electrical cabinet which will house the power supplies and stepper motor drivers. So I decided to finish working on the base for the router.

i needed a way to secure the table top to the sheet metal cabinet base. I purchased a pair of 1" aluminum angles and bolted them longitudinally to the cabinet base. Then I laid out the table top and drilled holes through the table top and through the angles. Then the table top was secured to the base with 1/4" x 2" carriage bolts. The holes in the table top were counterbored so that the bolt heads would not protrude above the table surface.

I then bolted the electrical cabinet to one end of the cabinet base.

See attached photos.
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Discussion Starter · #10 ·
CNC Controller - Part 1

I spent a lot of time and research before making a decision regarding the type of machine control I wanted to implement. This is also the riskiest purchase I will be making which I will explain as we go along. Naturally, one of the major factors would be cost. But there are other factors to take into consideration such as ease of implementation, software requirements and environmental considerations. In the end, the decision comes down to whether you want a PC controlled CNC machine or do you want a stand-alone machine with integrated controller.

Let’s discuss PC control first. To begin with, you need a dedicated PC for the CNC machine, preferably a desktop unit. It does not have to be a high power PC, but it is still an additional cost and it has to operate in a dirty, dusty environment. Then you have to buy the software to run the CNC. The standard appears to be Mach3. Why would you go with anything else when there are so many resources to refer to? But the cost is $175 per license. Then things start to get tricky. You need a so-called breakout board to interface between the PC and the stepper drivers and other peripherals. There are lots of cheap Chinese devices out on the market and there are lots of horror stories associated with them.

If you want to avoid the risk of dealing with junk then the Smoothstepper seems to be the unanimous choice. But that is another 200 bucks. Then I am still going to install all of this gear into an enclosure and wire it all up which will cost at least another $200. To top it all off I would want to have an MPG (Manual Pulse Generator) in order to facilitate moving all three axes manually.

So what about stand-alone controllers? Well, the first thing is you don’t need a dedicated PC. You can do all of your design on a remote PC, transfer this to your CAM software (on the same PC), then load the G-code file onto a USB drive and plug it into the CNC machine controller. Seems pretty simple, but do I need to buy any additional software? The short answer is no. What you need to buy is the hardware with integrated firmware. At the present time the best stand-alone solution seems to be (for me at least) the 4 Axis 500KHz Linkage Offline Motion Controller System RMHV3.1/DDCSV3.1. It is available from Amazon for $275 and includes a 100 Pulse Handwheel MPG with Emergency Stop. In summary here are some specifics:
  • 4.3 inches TFT screen, resolution ratio: 480*272;
  • Input power: 24~32VDC;
  • Output power: 0-10V, mainly for spindle speed
  • MPG Resolution: 100PPR;
  • 17 operational keys;
  • Supports the USB flash drive to read the G code,and the size of G code file has no requirement;
  • The highest uniaxial output pulse is 500KHz and the pulse width can be adjusted.
  • It supports most common stepper motor drivers
From a cost and operating standpoint, my decision was the Offline Motion Controller System RMHV3.1/DDCSV3.1. Keeping my fingers crossed that this was not a big mistake! We'll know in the next few days as I get this prepped and wired.

A word of warning! This is definitely NOT plug and play. For one thing, the manual is written in Chinglish which is full of grammatical and syntax errors. Therefor if you are not familiar with concepts such as open collector outputs and optically isolated grounds I would advise staying away from this controller.

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Discussion Starter · #11 ·
CNC Controller - Part 2

I wanted to minimize the number of wires and cables and I wanted a hand held controller similar to the CNC Router we have at work. I also did not want a separate MPG and its associated wiring to deal with. My solution was to disassemble the MPG and mount the individual components along with the controller in a 7” x 7” x 2” plastic enclosure. This way I could wire the MPG components directly to the controller inside the enclosure. The rest of the connections to the main electrical cabinet are made via a DB25 connector.

The RMHV3.1 has input connections for end of travel limit switches on four axes. I chose to go with soft limits and that saves eight wires plus ground that does not have to go to the main electrical panel and then eight separate pairs going to limit switches on the machine. I will install hard limits for home in the X, Y, and Z axes.
Before cutting the openings for the controller and associated components, I covered the enclosure with painters tape to make it easier to mark the cut lines and to protect the enclosure finish. The tape would be removed after all the cutting and fitting was done. I then measured and laid out the openings for the parts I harvested from the hand held MPG and mounted everything in the case.

Next step was to wire up the controller. If I were to utilize all the I/O available on the controller, it would require a 37 pin DB connector to link it with the main electrical cabinet. By selecting only the functions I intend to use (i.e. eliminating end of travel limit switches) I was able to utilize a 25 pin DB connector.
The connections to the RMSV3.1 are divided up into four ports:
  • MGP Port – manually generates pulses to drive stepper motors
  • Stepper Port – Connects to stepper motor drivers
  • Spindle Port – Connects to VFD for spindle control
  • Input Port – For all peripheral devices i.e. limit switches, probe, etc.
I started the wiring by connecting the individual components to the MGP port. This did not involve connections to the DB25. The individual components that were wired into the MGP port are:
  • E-Stop button
  • Rotary Encoder
  • Speed selector switch
  • Axis selector switch
Attached is a chart I developed as an aid to understanding and wiring the MPG components. SW1 and SW2 refer to the selector switches for speed and axis. The colors correspond to wire colors to aid in identification.

Next it was time to wire up the DB25. Once again I developed a chart to keep the connections and pin numbers straight. Colors on the chart matched the wire colors. The DB25 utilized crimp pins that were then inserted into the connector housing. This saved a lot of soldering. I used ferrules on the other end for insertion into the RMSV3.1.

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Discussion Starter · #12 ·
Missing Pieces

I decided to take a break from controls and wiring in order to check out all of the mechanical components in the kit.

After unpacking all of the mechanical parts, I started to layout all of the structural members to see how everything would fit together. It became Immediately apparent that I was missing a 2040 member 750 mm long. This is the center structural member that supports the spoiler board. Also missing were four end plates that join the 2080 longitudinal members to the 2040 horizontal members.

Even more surprising, there were additional structural members included that I have no idea what to do with. These are:

2 pcs. – 2080 x 28” long
2 pcs. – 2040 x 18” long

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If anyone has any idea what these additional pieces are meant for I would love to know.

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Discussion Starter · #13 ·
CNC Controller - Part 3

OK, Great! I’ve got all the MPG wiring finished and also the wiring from the DB25 to the controller finished. However, I did not connect any wires to the Stepper Port. I’m going to connect the wires from my breadboard test setup to the controller.

I already tested the motors and the drivers using the Arduino as a pulse generator, so I know we’re good on that end. Now we get to see how the MPG works and if the controller can run the stepper motors.

Step 1 is to test the MPG unit. I connected the drivers mounted on the breadboard to the RMSV3.1 controller. Then I switched the controller MODE to MPG and selected the X-axis using the rotary switch on my control box. Then by rotating the encoder wheel I was able to get the X-axis stepper motor to turn. I tried all three speed settings using the rotary switch on the hand held controller and that seems to be working correctly. This was then repeated for the Y and Z axes.

There are three speed positions available, 1X, 10X and 100X. The 1X position results in a very clunky motion and in my opinion not very useful. The 10X gives a nice smooth motion and 100X results in a very rapid but smooth motion.

I switched the controller MODE to CONT and used the buttons on the RMSV3.1 to move the stepper motors. I was very pleased to see that all the motors performed very smoothly and quietly at 100% speed setting. I should also mention that I had the microstep setting at 8 and the current limit at 2.84 Amps.

Now that I’m satisfied that the RMSV3.1, MPG, stepper drivers and stepper motors are all playing nice with each other, it’s time to look at the overall electrical arrangement. The first step is to disconnect the drivers on the test bench from the RMSV3.1 and connect the wires from the DB25 in the hand held controller to the corresponding terminals in the stepper port. Then we need to migrate all of the components from the test bench into the main electrical cabinet which will be the subject of my next post.
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Discussion Starter · #16 ·
Hi Tim

Glad you are enjoying the build. I didn't realize how much work is required to keep the thread going so I appreciate the feedback.

You are spot on about the heat sink. The diodes drop 1.4 volts each half cycle so at 9 amps we have to dissipate 12.6 watts continuously since this is a full wave bridge. See attached.

Stay tuned for more fun and games as I figure this puppy out.

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Discussion Starter · #17 ·
Electrical General Arrangement

One of the issues I’ve been struggling with is the overall arrangement of the electrical controls and wiring. After considering all of the relevant factors I came up with the following design criteria:
  • The only thing mounted on the wall will be two Edison receptacles, one for 110 VAC and one for 220 VAC; thus there will be only two cables going out to the wall, everything else will be mounted on the router.
  • The RMHV3.1 will be mounted in a hand held box and this will be our primary control; in addition to the RMFV3.1 we will incorporate an MPG and E-Stop.
  • The VFD for the spindle will be mounted in its own separate cabinet with EMI filter and 12 VDC power supply for cooling fan. (220 VAC supply)
  • Everything else gets mounted in a separate cabinet (110 VAC supply); this includes 36 VDC linear power supply, 24 VDC auxiliary power supply, 24 VDC power supply for RMHV3.1, 12 volt power supply for system cooling, stepper drivers and everything else.
Main Power Panel
Inputs and Outputs
In order to finalize the layout it was necessary to define all of the inputs and outputs into the main power panel. The inputs would be:
  • 110 VAC main power
  • DB25 from the master controller
The outputs were determined to be:
  • 4x cables to the stepper motors
  • 3x cables to the Home limit switches
  • 1x signal cable to the VFD cabinet
  • 1x power cable (24 VDC) for the contactor coil
  • DB25 connection to RMHV3.1 master controller
Main Power Panel Components
  • IDE power entry module including fuse and EMI filter
  • ON-OFF push button switch DPST
  • 36 VDC power supply for stepper drivers consisting of:
  • Toroid transformer
  • Full Wave bridge rectifier
  • 10,000 uF smoothing capacitor
  • 24 VDC power supply for RMHV3.1 master controller. This is a small DIN mounted supply rated at 1 amp.
  • 24 VDC power supply for Contactor coil
  • 12 VDC power supply for cooling fans
  • 4x Stepper Motor Drivers
  • 2x cooling fans and filters
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VFD Cabinet
I wanted to isolate the Variable Frequency Drive (VFD) from the main electrical cabinet for two reasons. The first reason is that it uses 220 volt AC power and I did not want to mix the two high voltages in the same cabinet for safety reasons. The second reason is that all VFDs generate a lot of electrical noise which can be transmitted back through the power lines and also radiated to nearby components.

Being extremely lazy I did not want to turn on two separate switches – one for 110 VAC power and another for 220 VAC power. That is the reason for the contactor. Thus when I turn on the AC power to the main electrical cabinet, it will energize the contactor and power up the VFD.

I had an old metal electrical box that I rescued on a dumpster diving expedition. My original thoughts were to mount the VFD in this enclosure. However as this build is progressing I am having second thoughts. One half of the router base is a set of drawers for storage. The other half is completely open space. At this point I am leaning toward mounting the VFD on the back wall of this open space along with the contactor and EMI filter. There should be enough air circulation so that I would not have to install a cooling fan.

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I found a nice piece of aluminum plate in my garage stash and laid out the VFD components on it and they fit quite nicely. That ices it! The old steel enclosure goes back to the dumpster and the VFD and associated components will go inside the router base.

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So to summarize:
VFD Assembly Inputs:

  • 220 VAC @ 20 amps
  • 24 VDC for contactor coil
  • 0-10 VDC for spindle speed from RMSV3.1
  • Open collector output from RMSV3.1 for spindle ON/OFF
  • Control Ground
VFD Assembly Outputs:
  • 0-220 V variable frequency to spindle
To be determined: Where to locate the 12 volt supply for spindle cooling pump and fan.

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Discussion Starter · #18 ·
Mystery Solved!

Back in Post #12 I reported that I was missing a piece of 2040 that supported the spoiler board as well as end pieces that attach the 2080 longitudinal rails to the 2040 horizontal members.

In that same post I reported that I had 2 pieces of 2080 and two pieces of 2040 that I had no idea what to do with. They were not mentioned in the construction manual. While surfing the CNC net I found a video describing an upgrade to the standard OX build. It consisted of adding an additional 2040 horizontal member on each end to stiffen the frame and a couple of 2080 longitudinal members to support the spoiler board.

It seems as though this upgrade was incorporated into the kit, and that's a good thing! :giggle:

The end plates that I thought were missing have also been included. However they are no longer simple triangle plates. See photos.

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An unexpected surprise!

While taking a closer look at all of the structural members I noticed that the ends were pre-tapped for M5 threads. What a time saver this will be not to mention lubrication mess and chips to clean up. :giggle:

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While taking a break from the electrics I Managed to get all of the wheels assembled. Each assembly consists of two bearings, a spacer and a wheel. The entire assembly is pressed together. I used a 5 mm bolt to ensure concentricity and put the assembly between a pair of washers. I threaded a nut onto the bolt and held the nut in a vice while I tightened the bolt. Worked like a charm!

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Discussion Starter · #20 ·
Today I began working on the gantry end plates by bolting on the stepper motors. Next I attempted to install the rollers on the opposite side of the gantry plate and immediately hit a snag. The drawings call for M5 x 30 mm low profile screws for attaching the roller assemblies to the gantry plate. I searched high and low and could not find these screws. I went on line and ordered 30 of these buggers and now I have to wait on the USPS. Meanwhile I thought I might bore you with how and why I selected the spindle for my CNC router.

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The Router Spindle

Like most everything else involving CNC routers, there are a variety of spindle types out there. Some made for wood, some made for metal, etc. As usual there are many factors involved when choosing a spindle for either your pre-build machine, or your homemade CNC machine.

If you are building a CNC machine, then you also need to make important decisions regarding the router spindle. Again, I realize a lot of hobbyists are bound by budget and that surely applies to me. After all, that’s part of the challenge. However, there are many choices to choose from within the same price bracket.

One of the most important decisions for the hobbyists, I believe, is the noise level. If you are anywhere near neighbors or your own house, then this is a huge consideration. You don’t want to be running an extremely loud machine for hours at a time.

When looking at trim routers that can be adapted for CNC use, I see that they are all in the 1 HP range. This is equivalent to 746 watts of power. So this gave me a good starting point. However when you look at standard routers such as the Bosch 1617es and the DeWalt DW618K, they are both rated at 2.25 HP or 1.68 kw. This is sufficient power to more than handle any woodworking jobs I will attempt. Many spindle motors are listed by their rating in kilowatts instead of horsepower, so I will be searching for a spindle motor in the 0.8 to 1.5 kw range.

A 1.5-KW motor is a good choice for mid-sized to smaller machines, as well as even some large benchtop machines. You can perform the most common operations on wood and plastic workpieces as well as cut out parts from aluminum sheet.

220 volts vs. 110 volts
While it's said that an electric motor doesn't "know" the difference between 110 and 220, your electric service will. A motor running on 220 pulls half the amperage than on 110. Thus, if you want to use a 2 HP motor, it will pull about 18-21 amps on a 110 circuit. If, however, you want a 2 HP (1.5 KW) motor on your CNC machine running on 110, you'll have to furnish a 30 amp circuit which means a new breaker and heavier wire since pulling 20+ amps on a 12ga. wire can be done, but you're asking for trouble, a possible fire, and complaints from family members when the lights blink every time you turn on the machine, not to mention numerous breaker trips. Since the wiring is already in place, I can convert to 220 by simply installing a 220 volt breaker in the panel box. It’s a no brainer!

Air Cooled vs. Water Cooled
While searching through the advantages and disadvantages of hand held routers in the 1 HP range, one of the complaints was that these machines tend to run very hot, often to the point where the operator can no longer hold the router. Looking over the many choices available, it seems to me that 1 HP is the breakeven point for air vs. water cooling. There are other factors impacting how hot the router will get. Some jobs on the CNC may run an hour or more. Another factor is how hard the machine is working, i.e. type of material, depth of cut, etc. So, all things being equal, IMHO a water-cooled spindle is preferable to air cooled once we hit the 1 HP (.746 KW) point. Closed loop cooling systems for computer MPUs are cheap and readily available. In addition, water-cooled spindles are quieter than air-cooled.

Why Choose VFD Spindles
VFD spindles are a great alternative to using hand held routers to power your CNC machine. Hand routers are designed for small jobs in your hand not for running for hours on end. Hand routers often handle this unintended workload surprisingly well however they are in almost every way the wrong tool for the job.

VFD Spindle Pros:
  • Significantly quieter than handheld routers
  • Better speed range and availability of collet sizes.
  • Much higher duty cycle – they are designed to run all day.
  • No brushes to wear out.
  • Higher torque in lower speed range
  • Considerably better tool runout (accuracy) which leads to higher quality output and longer tool life.
  • GCode Control (automatic control from software) – Most often (depending on the CNC controller) you can start/stop and set the speed of the spindle via G-code and also override these speeds from the machine control software in real-time.
VFD Spindle Cons:
  • Price – doing it right with approved products will absolutely cost more than picking up a handheld router and bolting it to a CNC machine.
  • Potentially RF Noisy (electronically not audibly) – Cheap or incorrectly commissioned/programmed VFD’s can send you down a rabbit hole chasing EMF noise-causing all sorts of failures during machining. It’s hard to chase noise without an oscilloscope and training.
At the end of the day the advantages of VFD significantly outweigh the disadvantages. Today we have pre-engineered systems that are truly plug and play.
And the Winner is….
Vevor 1.5kw 220v Water Cooled Spindle Motor Kit: VFD, Clamp, Pump, Pipe, and 14pcs ER-11

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The kit includes the spindle motor itself, the VFD, fourteen collet inserts, a 5-m roll of tubing, a submersible water pump, and a spindle motor mounting bracket. The collet size this motor uses is ER11, which is relatively small and only allows you to use bits with a shank less than 7 mm (.276”). You could upgrade the collet assembly, but you would have to consider the limitations of the motor before attempting to put any really large bits in it. With that having been said, it is highly unlikely that we will be using tools with a shank greater than ¼” (6 mm).
  • Size: 1.5 KW
  • Cooling: Water cooling with pump and hoses included
  • Control style: 220-V AC VFD with computer control
  • Collet size: ER11
  • Rated speed: 0-24,000 RPM
  • Price: ~$270
  • Available from: Vevor
The only concern I have is the quality of the VFD drive at this price point. However I will go with this package to start with. If the drive begins to present a problem I will replace it with a Hitachi WJ200-015SSF. One other note – I plan to ditch the pump supplied with this package in favor of a closed loop CPU cooling system.
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