Home CNC with Arduino II - Mechanics


In this article I will take a brief look at the mechanical side of the Homemade CNC with Arduino Root 3.

Mechanical assembly it's not complicatedalthough it does requires patience to collect the components, as you will probably order most of the parts from China and it will take time for them to arrive.

In this kind of projects it is normal that the time is long because most likely you will have to make several orders, as it is very difficult to know exactly what you need at the first time. There will be things that you will have to wait to order until you have others in your hands to see exactly how everything fits together.

We can divide the mechanical assembly into four parts:

  1.  3D printed parts
  2. Wooden parts
  3. Tubes and bearings
  4. Hardware

I will try to give you some advice on each of them as we go along.

3D printed parts

You can download the STLs for the printed parts in 3D from the Thingiverse project page.

Some of the pieces have been improved by other partnersI will give you some alternatives below that I think are better than the original ones.

You can find more interesting information in the Root CNC website. I recommend that you take a look at it to familiarise yourself with the material and information it contains for that you know, when the time comes, what you can count on.

Of course, if you have any questions You can also leave a message here, in commentsand I will try to answer you.

3D printing leads to a long time y a lot of filament.

I think it took me about five dayswith the printer running almost 24 hours a dayand approximately 2Kg of PETG filamentmaybe something else.

About the type of filament, don't hesitate, prints the parts in PETG (unless your printer is one of those that doesn't do well with PETG). PLA is not rigid enough and ABS will probably give you a lot of warping and adhesion problems.The pieces are quite large, as many of them are quite large.

Every cloud has a silver lining, so while you're printing parts, there's time for things to arrive from China.

The rigidity of the parts is very important. I recommend, in general, a infill of a 50%as a minimum, and four perimetersat least.

When it comes to printing, the positioning of the parts on the printer bed is important to ensure that you have as few problems as possible. At this page you can see the orientation.

Many of the pieces that I printed with less infill and less perimeters didn't last long and it's very annoying to have to change pieces after a short time. Also, many of them didn't have the layers well adhered and this later caused problems.

These are the first pieces I printed; at the beginning, as I said, I changed many of them. You can see them bigger by clicking on each one of them:

Keep in mind that the parts to be printed have a lot of plastic and will take several hours to print.

I recommend using a quality printer. I use a Creality CR-10. Here are a couple of the best selling Creality printers, highly recommended.

Creality 3D printer series (Halot-Mage Pro)
  • 1. REACH 300MM/S: The new 2024 version of the Creality Ender-3 S1 ProX 3D printer is equipped with a print speed of 300mm/s, making it four times faster than conventional 3D printers. This fast printing capability ensures a quick turnaround time for models, providing users with a satisfying printing experience and enabling them to obtain high quality models in a short time.
  • 2. "SPRITE" FULL METAL DOUBLE GEAR DIRECT EXTRUDER: The Creality Ender-3 S1 Pro 3D printer upgrade features the "Sprite" Full Metal Double Gear Direct Extruder, an improved direct extruder with a thrust force of up to 80N. This extruder ensures smooth feeding and discharge of filament without slippage, improving the overall printing experience. It is especially effective in printing flexible filaments such as TPU, providing versatility and reliability in various printing applications.
  • 3. UPGRADED 300℃ HIGH TEMPERATURE NOZZLE: The Creality Ender 3 S1 Pro 3D printer features an upgraded brass nozzle capable of withstanding temperatures up to 300℃. This high-temperature capability expands the range of filaments supported by the printer, including ABS, PETG, PA, PLA, TPU and Wood. The versatility provided by this nozzle upgrade allows for a wider variety of printing materials, offering more possibilities for creative projects. In addition, the improved nozzle contributes to smoother printing, resulting in better print quality and finer details on printed models.
  • 4. CR TOUCH AUTOMATIC LEVELING SENSOR: The CR Touch automatic leveling sensor for Creality Ender 3 s1 prox offers quick adjustment of the nozzle print height on the hotbed, ensuring accurate printing. It features a 16-point auto levelling programme, which collects more samples compared to the BLTouch's 9-point system. This enhanced sampling capability improves bed levelling accuracy, resulting in better print quality and consistency.
  • 5. GREATER PRINTING ACCURACY AND EASE OF USE: The new Creality Ender 3 S1 Pro features a twin-screw, twin-motor Z-axis design, similar to the Ender 3 S1, which improves printing accuracy and ease of use. This design ensures smoother and more synchronous operation, reducing the appearance of lines and ridges on printed objects, thus improving overall print quality. In addition, the printer can be quickly installed in just six steps, further enhancing user convenience.
Official Creality Ender 3 Pro 3D Printer with UL Certified Power Supply and Flexible Magnetic Plate for Resume Printing 220x220x250mm, 3D Printer for Beginners
  • UL-certified power supply: The Ender 3 Pro comes with a UL-certified branded power supply, which protects your printer from unexpected power surges, which can heat the hot bed to 110 ℃ in just 5 minutes. Customer service: if you have any concerns about the printer, please feel free to contact us via Amazon message. We will reply soon.
  • Removable flexible magnetic plate: provide complete protection for the build plate of your 3D printer and ensure a constant temperature across the entire build surface. Easy to remove printing models after cooling.
  • Print resume function: Ender 3 Pro can resume printing from the last registered extruder position after unexpected power outages.
  • Semi-assembled kit: This easy-to-install kit comes partially assembled, allowing you to learn about basic 3D printer construction as you finish assembling it. A fun STEM educational experience in mechanical and electronic engineering.
  • Thermal runaway function: The thermal runaway function is pre-installed on the motherboard. You do not have to load it yourself.

There is nothing worse than having been printing for hours and having spent almost a kilo of plastic, only to suddenly realise that the print has been ruined by the poor quality of the printer and you have to throw the plastic away and start again.

You will see that of some pieces there are variations:

First variation: On the one hand, you have a first big variation depending on whether you use a metric pipe (in millimetres(as we use it in Spain) and another one for imperial measures (inches). These pieces have to match the tube (the important thing is that if the tube you are going to use is 20 mm the pieces you print are the 20 mm metric ones).

Second variation: Depending on the transmission belts you will have to use one or the other. It basically depends on whether they are, for example, GT2 straps, such as those for 3D printers, or other types of straps.

Third variation: Depending on the spindle, motor, Dremel or whatever you use. There are different pieces depending on what you decide on.

In addition, for some of the pieces, you will see that there are versions of the pieces made by other people improving some aspect or providing some variation. I recommend the following:

Root 3 CNC Box Section Linear guide Remix

It has a small elevation on which the bearing sits so that you save putting a washer.

I haven't put these on yet, but I will when I have to change them.

It is in this Thingiverse page.

Alternative Belt Clamp for Root 3 CNC

Makes belt tensioning much easier of the X-axis. With the original part the tensioning is very complicated.

I haven't put this part on yet either, but I will do it when I have to touch this part of the machine.

It is in this Thingiverse page.

A tip: Be careful with the filament you use. There is a lot of difference between filaments.

Lately I've been having a lot of trouble with PETG filament and I'm using it to make parts for the CNC, SUNLU PLA plus filament.

Here are some links to SUNLU PLA plus filament on Amazon:

SUNLU PLA Plus 3D Printer Filament, 1.75mm PLA+ filament, enhanced hardness 3D filament compatible with FDM printers, dimensional accuracy +/- 0.02mm, 1kg(2.2lbs) spool, Grey
  • ①【SUNLU 3D PLA Filament Plus】SUNLU PLA+ has higher hardness than normal PLA. Say goodbye to brittle filament. SUNLU PLA+ filament has high strength, excellent adhesion, lower shrinkage, no bubbles and no clogging.
  • ②【Carefully wound filament】 SUNLU's carefully wound filament technology can prevent filament winding, twisting or disconnection during printing, reduce the risk of 3D printing plugs and make your printing smoother.
  • ③【No clogging, no bubbles】The improved flow of 1.75mm SUNLU PLA+ filament will no longer clog the bed probes of FDM 3D printers. PLA PLUS filament is free of impurities and bubbles and the printing process is smooth, allowing for brilliant 3D prints.
  • ④【High precision +/- 0.02mm】The PLA+ 3D printer filament is 1.75mm diameter, precision +/- 0.02mm; 1kg (2.2lbs) spool. It has a very tight diameter tolerance and perfect roundness, minimal deformation. Increase the finesse of your 3D printing objects.
  • ⑤【High compatibility and vacuum package】. Compatible with 99% FDM 3D printers and 3D pens. SUNLU PLA PLUS filament vacuum packed provides better printing results. PLA+ filament is made from starch raw materials derived from renewable plant resources.
PLA Filament 1.75mm, SUNLU PLA 3D Printer Filament, Dimensional Accuracy +/- 0.02 mm, 1kg Spool, PLA Black
  • 【Hardness-enhanced PLA filaments】 SUNLU premium PLA filaments have the advantages of incredible printability Optimised print quality, high purity with low shrinkage and excellent layer bonding, meeting your demands for functional parts printing projects with higher toughness.
  • 【Dimensional accuracy and consistency】. These tough PLA filaments are strict tolerances. Diameter 1.75 mm, dimensional accuracy +/- 0.02 mm without any exaggeration; 1 kg spool (2.2 lb).
  • Clog-free, bubble-free and easy to use】. Complete drying for 24 hours before packaging and vacuum sealed with desiccants in a nylon bag. Recommended PLA extrusion temperature / filament nozzle 215-220℃, bed 70 ℃.
  • 【Wide compatibility】. Works and harmonises perfectly with all common 1.75 mm FDM 3D printers, thanks to the high quality standards in terms of manufacturing precision and the small diameter tolerance of +/- 0.02 mm.
  • 【No risk】Free trial, 30 days money back if not satisfied. One month free trial, 30 days money back if you are not satisfied. Spool diameter: 8" - Spool width: 2.5" - Spool hub bore diameter: 2.20".
GEEETECH PLA Filament 1.75mm for 3D Printing, 1kg Spool, Black
  • 1. 1 kg of 1.75 mm spool of PLA filament in a vacuum pack.
  • 2. No impurities, no clogging and unbreakable filament
  • 3. Recommended printing temperature: 180-210 ℃.
  • 4. Diameter tolerance +/- 0.02 mm
  • 5. Environmentally friendly, made from starch raw materials derived from renewable plant resources.
SUNLU PLA+ Filament 1.75 mm, PLA+ 3D Printer Filament PLA Plus 1KG,Enhanced Strength,Neatly Wound, PLA+ 3D Printing Filament, Dimensional Accuracy +/- 0.02mm, Black
  • ①【Strong and robust PLA+ filament】The SUNLU PLA+ filament 1.75 mm is an improved version of normal PLA filaments. Its hardness can reach more than 11 times that of PLA filament. The optimized PLA+ filament can meet your demands of high tenacity printing projects.
  • ②【Neatly Wound Filament】SUNLU PLA+ 3D printer filament, perfect roundness and very precise diameter tolerances, good winding, no overlapping or tangling. Smooth and consistent feeding without clogging nozzles or extruders. Improves 3D printing success rate.
  • ③【Dimensional accuracy and consistency】SUNLU has strict production process and diameter control equipment to ensure that PLA+ filament has an accurate diameter tolerance of +/- 0.02mm, 1kg (2.2lb) spool.
  • ④【No clogging and no bubble】Full mechanical winding and strict multiple quality manual inspection (24 hours drying and vacuum sealing), which ensure SUNLU PLA+ filament is easy to feed and with better adhesion layer.
  • ⑤【Professional after-sales team]】SUNLU is a high-tech enterprise specializing in R&D, production and sales of 3D printing filament, 3D printer, 3D pen and 3D resin. We will offer professional after-sale service, choose SUNLU to buy without worry.
Silk PLA Plus Filament, 1.75mm 3D Printer Filament, Shiny Metallic Silk PLA+ 3D Printing 1KG Spool, Dimensional Accuracy +/- 0.02mm, Silver
  • Love 3D Printing: Shiny Silk PLA Plus 3D filament has the advantages of high purity with low shrinkage and superb layer bonding, meeting your demands for different printing projects.
  • 3D Printer Silk PLA Plus Filament Using Tip: Silk PLA Plus 3D Printer Filament Extrusion/Nozzle Temperature 210-220℃, bed 60-70℃. Diameter 1.75mm, dimensional accuracy + / - 0.02 mm without any exaggeration; 1 kg spool (2.2lbs). Spool Width: 2.5", Spool Diameter: 8", Spool Hub Hole Diameter: 2.20".
  • Strong Layer Adhesion and Printing Smooth: With excellent first layer adhesion, improved adhesion between layers, reduced warping, shrinking, curling ,we guarantee a Smooth & Stable Printing Experience.It mades from natural renewable resource, environmental materials and the filament is 100% biodegradable & non-toxic.
  • Compatible with most 3D Pen and FDM 3D Printer: Warhorse 3D SILK PLA+ filament works perfectly with most 1.75mm FDM 3D printers,3D Pen. Come with vacuum packed with desiccant to maintain a low moisture content.
  • Great Brand with Lifetime Warranty: with a promising lifetime warranty, it will be your risk-free choice, please be assured that we'll always stand behind our products.

Wooden parts

There are only four wooden parts. They are the ones that hold the bridge o "gantry (portal), as it is often called in the NCC world.

Just as they say that the Germans are very good industrialists because they make round holes, these parts are the ones that make everything "fit". So that when the CNC has to make a right angle, it is 90º and not 89.9º or 90.1º, which makes a circle come out perfectly round and not like an ellipse. In short, that the precision of these parts is very importantIt is not so much the external cut, but rather that the position of the holes is as precise as possible.

Ideally, these parts should be made for you someone who already has a CNC. If not, as was my case, the best thing to do is to get some paper templatesIf possible, make the cuts and holes by hand as well as possible and, when the CNC is already working, return to make the final ones.

Here are some photos of the construction of the first pieces, in MDF (the definitive ones were made in phenolic plywoodwhich is much tougher and has much less flexion).

Tubes and bearings

The Root CNC is cheap because, among other things, instead of using commercial linear guides (which are very expensive) it uses an ingenious system of "skates with inexpensive skateboard bearings that slide on square tubes.

The tubes in the normal version of the Root 3 are 20x20mm (there are other versions with larger tubes for more rigidity).

These tubes can be made of steel or aluminium. What is important is that they are as rigid as possible.

I first used 20x20mm aluminium tubes bought at Leroy Merlin with a 1mm wall. Although the CNC worked, these tubes were not rigid enough and the finish was not good, the machine sometimes jammed and jerked. After a short time I changed them for 20x20mm steel tubes of 1.5 mm wall, also bought at Leroy Merlin.

My advice: no aluminium tubebuy the stiffest and thickest-walled steel tube you can find. This is something I have pending on mine, to change the tubes for others of at least 3 mm wall. The performance is acceptable with the 1.5 mm ones, but I am sure that with the 3 mm ones it will improve a lot.

As for the bearings, I have little to say. I bought the cheapest I found on AliExpress and it's working fine. I'm sure that with better quality bearings it would work better, but, as I've never used better bearings, I can't tell you.

Of course, CNCs kick up a lot of dust, a lot of shavings, and a lot of dirt, however they are made. closed bearingsDo not even think of using air ball bearings in a CNC.


Nuts, bolts, washers... crazy... You never seem to finish buying screws for the Root 3, you could write a book.

One of the worst things is that there is no shopping list and in conditions with models and quantities of screws. You have to base yourself on the list that comes with the documentation and then go on researching and seeing what is missing (I assure you that you will have to place more than one order for screws, and probably more than two).

Be careful, because not only do you have to buy a lot of measures but many types different.

Don't forget the washersThere are many and of many types...

There is a good budget in hardware stores. I recommend you to buy the screws at RationalstockIt's where I've been buying all my screws for years and it's the cheapest screw place I've found. worldwide (and by far).


Have you already read the introduction to the CNC? If not, do it now: Homemade CNC with Arduino Root 3.

Building the Root 3 CNC has been a very nice and interesting projectand it's amazing what you can achieve learn.

It is not difficult toIt's simply a matter of going step by step and with patience.

I will soon write the other articleswith more detail on the construction of each of the parts. Don't forget to subscribe to receive a message when they are there so you don't miss anything.
If you enjoyed the article, I would be very grateful if you could spend a minute to leave a comment below.

3 thoughts on “CNC Casera con Arduino II – Mecánica”

    • Thank you very much, JuanMa.

      I'm glad you like it and find it useful. I hope that in the future you will continue to find things that you find interesting.

  1. You would have made a guide to guide us through the swarm of screws, by parts ... searching the internet there is none, and the documentation from the creator leaves much to be desired, although it looks like a good machine compared to MPcnc.


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