My build has finally begun and in this post I will take you on the building journey. Make sure you have read part 1 here , part 2 here , part 3 here

Lifting it up in the shed

It’s been some time since my last update. The machine is complete, but it’s worth noting that I had to construct a shed specifically to accommodate it; the machine proved too large for the existing brick structure.

I bought a garage “engine block” crane to lift the approximately 350kg structure in the shed. You really notice that using the right tools in a situation likes this makes huge amount of difference.

Replication method at work

After moving and leveling the machine I had to make the surface of the aluminium extrusion flat in order to mount the rails to it.

It is a bit of a messy situation but hey! it works.

After making the surface flat I cut out the slot with a hot-knife in order to mount my rails to it.

Adjusting the gantry level

I used the metal epoxy “gap filling” method to level the gantry vs the Y1 and Y2 gantry rails:

I used Mirror glaze wax release on the gantry to make sure it just fills the gap and does not stick to the gantry extrusion itself. Not this works REALLY well!

After making sure it is level, I let it cure.

in a Dan Gilbart video I recently learned to make figure 8 motions when doing this. I tried it out and noticed it worked well. I did not actually check it on the surface plate but you notice that the surface is quite flat. Within >=0.0x mm I would estimate. Good enough for this part.

Mirror Glaze

Mirror Glaze Wax release; 16$

Aliexpress.com

Fixing the electronics

I decided to rewire the electronics from scratch. It worked out quite well I must say!

After I wired most of it on the desk I hung it on the wall and started connecting it to the CNC.

Finishing the mechanics

I kinda dropped and messed up the C5 1605 nuts I had on my spindles. As they were already too short anyway I decided to pick up some new ones from Aliexpress:

I was seriously impressed with how riged the DFU version of the ballscrew feels. There is no play at all. I later on measured it on the CNC itself with load and you dont see it budge at all. I can really recommend these C5 1605 DFU screws from Yixindianqi Store on Aliexpress.

So after completing most of the electronics, I went off to mount the spindle and servo motors. Initially, I had put the MAKITA RT0700 router on there; but that died very quickly after a little accident when I crashed it into the toolsetter.

Because the design of my frame is more of an afterthought … I had to add some way to mount the fixture table/wasteboard on the CNC. While it is not ideal to weld on a relatively precise machine frame, it was still the easiest method to do it.

After completing this stage I mounted 36mm of MDF plate to it and went on to the next step

Many small steps in between

So as it goes in a project. you lose focus on documenting a bit and do all kind of small steps. During this time I got probe basic working well on the CNC, tuned the servos and did some final adjustments on the mechanics.

Tramming and aliging the axis

So as in any precision machine build where your mechanics are to perfect, you are going to have to adjust the tram and yaw of the spindle.

I started first with fixing the “nod” of the spindle by putting in a 10mm endmill upside down and using an indicator to make sure the measured distance stayed the same while moving the Z-axis up and down. This was relatively quick to be fixed.

For the trimming (rotation of Z spindle ) I did the following:

So I 3d printed a spacer so I could mount my indicator on the spindle. Turned it round to make sure the distance of the indicated stayed the same. As my z-axis is quite heavy, I found the use of a strap quite useful to slowly get it in the right spot.

Making chips!

After spending some more time with the machine I made another short video where I did some more drilling and milling

Can it mill hardened steel?

So a question that comes up quite a lot is if the Lusintun BT30 ATC spindle can mill steel? The answer is yes, the spindle itself is not the limit. The stiffness of the machine is.

I did some testing on some hardened steel to make sure it could handle normal steel with ease.

Conclusion – Mightymill build Part #4

Since part #3 quite a lot has happened. The machine is together, is working and performing pretty well. As this is the first full CNC build that I have done there are plenty of areas that need improvement. One of the main things is to make the Z-Axis stiffer and make a better connection from the gantry to the ballscrew.

Other than that I’m happy with how it performs!

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The replication method is a widely used technique in manufacturing and metrology to obtain accurate copies of a surface. The method involves replicating the surface of a reference material onto a workpiece using a medium such as metalized epoxy. This article provides an overview of the replication method, including its advantages, limitations, and applications.

Replication Method:

The replication method involves using a medium such as metalized epoxy to make a copy of the surface of a reference material, such as a granite surface plate to a workpiece. The surface to be replicated is first cleaned and coated with a thin layer of release agent, typically some kind of wax. The release agent is allowed to dry and is buffed to a shiny surface before the epoxy is applied. The epoxy is applied to the setup by pouring or injecting it into the setup and then allowed to cure. Once the epoxy is cured, it is peeled (or hammered) of the reference material, leaving behind an exact replica of the surface.

Advantages of the Replication Method:

One of the main advantages of the replication method is its ability to produce accurate copies of a surface. The method is also relatively easy to perform and requires only basic equipment and materials. Another advantage of the replication method is that it can be used to replicate surfaces of different shapes and sizes, making it suitable for a wide range of applications.

Limitations of the Replication Method:

While the replication method is generally accurate, it is important to note that it is subject to certain limitations. One limitation is that the replication method can only produce a replica of the surface that is in contact with the reference material. If the reference material has any defects or irregularities, these will be replicated onto the workpiece.

Applications of Replication Method:

The replication method is widely used in metrology to produce accurate copies of surfaces for measurement purposes. It is also used in manufacturing to replicate surfaces for quality control and inspection. Additionally, the replication method can be used in the restoration of damaged surfaces, such as those found on antique furniture or architectural features.

Resources:

Academia:

There is a book from the 80’s or 90’s by a professor of a US university who writes about the surfaces replication method, and how they used it to make a giant 5 axis grinder… I just cant find it at this moment…

Ah, here it is!

Principles of Rapid Machine Design – MIT – Eberhard Bamberg:

https://my.mech.utah.edu/~bamberg/research/PrinciplesOfRapidMachineDesign/Principles%20of%20Rapid%20Machine%20Design.pdf

At-scale use of the replication method for big cnc machines – Rampf group:

https://www.rampf-group.com/en/aktuelles/blog/2021/how-to-2-replicating-mineral-casting-components-with-maximum-accuracy/

Replication techniques and portable machining in machine tool rebuilding – Molglice:

http://www.moglice.com/articles/replication_techniques/wrotethebook.html

PRECISION the easy way, making CNC parts too big for a hobby mill – @floweringelbow:

DIY experiment:

With most DIY builds the most difficult part is creating flat mounting surfaces for your carriages and rails. In my Mightymill build, I have the same challenges.

Creating precision surface copies using metalized epoxy

Total Time: 9 hours

Prepare your workpiece

Make sure it is free of oil, and has a decent amount of surface roughness for the epoxy to adhere to.

Prepare the reference surface

I used Miracle wax no.8 as a release agent. Follow the manufacturer’s instructions (I did 3 coats) with buffing in between. I used a 40$ <2um error small granite surface plate.

Prepare the metalized epoxy

I used West epoxy 105 + 206 hardner, although I’d think 209 might even work better. I did a 50/50 mix of epoxy + iron powder (<63um particle size).

Tape off your part

Note: I used a 3-4mm thick parallel to regulate the thickness of my epoxy layer.

Pour the epoxy

Make sure you remove all air and have proper coverage. This is actually the most difficult part

Let the epoxy cure

I think I let mine set for about 12 hours

Remove from the reference surface and inspect

Any overflowing epoxy you can just hit off with a hammer or grind it away with a die grinder. The initial surface is quite rough due to the remaining release agent on there and any defects of your reference material.

Optimize the surface roughness and flatness

You can use either something like a 123 block + abrasive, a “kitchen” flattening stone, or any other relatively flat material. I used some dishwashing soap + the above-mentioned iron powder to basically do a lapping operation to the surface.

After about 3 – 5 minutes of lapping the surface should be smooth with most of the high sports removed.

Inspect and repeat

There are various ways to inspect surface flatness. I used a Mitutoyo indicator, a 123 block, and a high-precision HGW20CC block as my reference.

The initial flatness before the optimization stage was about 8um over the whole surface. After a cycle of 1-3 times of optimizing and inspection, it is <= 2um. Which equals my reference material. Lapping becomes challenging because the materials just want to stick together. The main issue at this point is that this is extremely difficult to measure.

As you are at or nearing the requirement of lab-based CMMS or optical measurement methods.

You could make this perfectly flat by doing this to 3 surfaces and using the Withworth 3 plate method.

Does it pull a vacuum?

yes: https://youtube.com/shorts/egtODwy4WiE

Estimated Cost: 5 USD

Supply:

• Slow cure no shrink epoxy such as West 105 + 206
• Iron powder <63um particle size
• Tape

Tools:

• 123 block

Materials: Workpiece Reference material Mold release wax

Conclusion:

The replication method is a simple yet effective technique for producing accurate copies of surfaces. While it has certain limitations, it is a valuable tool in metrology, manufacturing, and restoration. It allows a hobbyist or a professional to make micron-to-sub-micron accurate copies of reference surfaces. And thereby able to create flat surfaces for DIY CNC machines or metrology equipment at a relatively low cost and low effort.

My build has finally begun and in this post I will take you on the building journey. Make sure you have read part 1 here and part 2 here .

Assembling the machine frame

It took a while, but finally I was able to move the machine frame in my recently cleaned shed and get it assembled. For me, the concrete filled machine frame was one of the most time consuming aspects of this build.

The leg assembly was the most difficult to move. While I had put GD-60S wheels under it, it is till a top heavy assembly which weighs 120kg. With a bit of sweat and hurt, I was able to position it and get the assembly going.

I was able to assemble it without too much hassle. To get it all square I had to use the Farmer’s jack to pull the legs inward as there was a slight misalignment. After that it is square (diagonal measurement) within 1-2 mm over a span of 1.6 meters. Which is fine for this application.

It all seems to fit pretty well. Time to go on to the next step.

Lets “rise” up!

It was time to make the riser plates. I used my old and not so trusted HBM BF25 manual mill for this. It actually had lots of troubles during this process. Wobbliness … (DC) motor brushed dying, and other fun electronics issues… But i got it going again and was able to finish the job.

As you can see in the image, the side finish of my milling does not look very good. As I mentioned before my HBM bf25 is quite wobbly and not in a good state. There is still quite some play in the column and in the gibs even after tuning.

As the side surface is not a critical one for my application it is not too bad.

in a Dan Gilbart video I recently learned to make figure 8 motions when doing this. I tried it out and noticed it worked well. I did not actually check it on the surface plate but you notice that the surface is quite flat. Within >=0.0x mm I would estimate. Good enough for this part.

Whetstone set

This set of whetstones was affordable at 25$ and I was able to get it locally quickly.

Aliexpress.com

It all fit well without too many issues. With such precision applications be sure to torque bolts and screws correctly. It is essential that you do in precision applications to ensure equal load and proper contact between surfaces.

After this I also ran the whetstones over it quickly to remove all the burrs.

In addition to this I had to buy the following items:

I used some 3mm thick ground steel parallels for equal spacing vs the alu block.

I used this method to ensure that the side of the extrusions meet the adapter plate perfectly at the same reference plane.

Finally! it is starting to look like a CNC!

Conclusion – Mightymill build Part #3

Moving and re-assembling the machine frame was one of my biggest hurdles. But once I got going it went relatively smooth. The Farmer Jack’s helped a lot with this.

I ordered some new goodies such as Delta ASDA-M controller, 400W ECMA 20b optical encoder ac servo motors. A 1 meter 000 grade granite parallel (all surfaces) and some nice steel AC servo motor mounts. It is now all on the train from China. Hoping for it to arrive at the beginning of December.

The next step will be making the adapters for the ball screws and motors, mounting the extrusions to the table and making the z-axis adapter so it can all be mounted together.

Stay Tuned!

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CNC controllers require understanding of the exact length of tools in order to compensate for any tool length differences between milling cutters.

In this article, I go over the various style of tool length sensors available. Evaluating aspects such as accuracy, versatility, and cost.

Lower cost mechanical tool setter

The lower-cost mechanical tool setter such as the HLTNC CNC tool length sensor which I reviewed here is the most popular method of tool length measurement for DIY hobby or semi-pro CNC machines.

There are various models available on Aliexpress and at other sources of these lower cost mechanical tool setters. Internally they are all constructed similar. There is a plunger where the end mill presses down and internally there is a switch that gets contacted when the plunger is moved down by a certain distance.

The repeatability of this style of tool setter has been shown and tested to be within +-0.01mm – 10um. For most DIY, hobby, and semi-pro CNC machining applications this is suitable.

However you will face some challenges with irregular shaped milling tools such is index-facemills or bigger tools that exceed the size of the plunger.

In addition this style of mechanical tool setter does not allow you to measure the tool width.

The elecrtical connection of this type of tool length sensor is quite easy. It with either have an NC or NO type switch internally which allows you to connect it to your cnc controller board such as an UCCNC or Mach 3 breakout board.

Non-contact tool setter

Non contact tool setting system often recognizable the U shape is one of the most common methods for automatic tool length measurement for industrial machines.

These non-contact tool setter work by sending a small laser beam from the sending fork to the receiver fork on the other side.

Due to its non-mechanical nature of it, the accuracy and repeatability of it tool length measurement is generally around 1 – 2 um for the more affordable models such as the Sick WF2. On the higher range of the spectrum, the Renishaw NC4+ achieves a repeatability specification of +-0.5um for smaller tools and +-0.75um for larger tools

An additional benefit of this type of non-contact tool length sensor is that it allows irregularly shaped tools such as big insert-based face-mills to be accurately measured. This can often be a challenge when using a contact-based tool setter.

In addition to that you can do width measurement of an milling tool. This is especially beneficial to capture catastrophic damage to a milling tool or to verify that the physical tool matches the tool size as set in the cnc controller such as linuxcnc or UCCNC.

This width measurement is usually less accurate than length measurement. One can generally expect about 20 – 50 um measurement accuracy using a non-contact

Endmills and other milling tools are often not completely flat on the bottom face due to cutting edges etc. To measure the longest point of the endmill accurately this kind of non-contact tool length sensor requires the spindle to turn (~1000 rpm) while measuring the lowest point of the milling tool.

On the second hand market such non-contact tool setters are available from just 10$.

Popular term for this on european ebay is “Gabellichtschranke” which translates to “Fork light barrier” – one example of this is the Balluff BGL000A which you can often find new or used for 20 – 40$

Premium – mechanical tool setter

In comparison to lower-cost mechanical tool setters that are often used in the DIY CNC community, there is also a premium style available that can achieve repeatability numbers comparable to or better than non-contact tool setters.

Renishaw OTS 3D touch trigger tool setter is one of such premium mechanical tool setters.

While listed as a mechanical tool setter in this article, internally it is just like the non-contact tool setter optically based to achieve better stability and accuracy numbers.

Brand new the Renishaw OTS 3D tool setter costs approximately 2000$ but used these can be found for about 500 – 1000 $ on places like ebay.

The Renishaw OTS 3D tool setter lits a repeatability specification of 1.00 um.

There are a few copies of this design on aliexpress but they are still quite pricey at 1000+ $. At that price point, I would advise to look at second-hand options in the west.

Conclusion

In this article, the various kinds of tool length setters are described with each having their pro and cons. For most hobbies and DIY use, a lower cost mechanical tool setter will be sufficient.

Looking for more versatility and better accuracy? have a look at (second hand) non-contact tool setters.

Are you a job-shop that is running VMC all day long, with coolant etc – for you the premium 3D mechanical tool setters for a brand such as Renishaw might be the right option.

In the past few months its little brother the PrintNC Mini which extends the PrintNC capabilities further but in a much more compact and cost effective platform.

Features of the PrintNC Mini

The PrintNC mini is the baby that came out of all the findings and learnings of the (opensource) PrintNC project. The main improvements are as follows:

• Dual HGH15 block bearings on the Y axis – Fixes the main stiffness issue which was often one of the first upgrades done for the PrintNC V3.0

• Triple HGH15 bearing block configuration for the X axis – This setup drastically increases the stiffness of the X axis and Z axis assembly

• Re-design of the Z-axis – Allows for a smaller overall package while retaining simplicity to build and overall stiffness

• In-chassis Nema17 stepper motors allow for a much more compact build

PrintNC mini specifications

The standard build has the following dimensions:

• Wasteboard 395 x 500 mm
• Y axis beams: 75×50 mm steel tube
• X axis beam: 50×50 mm steel tube
• Z travel: 110mm
• Y travel: 300mm
• X travel: 300mm

The PrintNC Mini is designed with parametric modelling. You can scale-up and scale-down the design within reason.

What makes the PrintNC so special vs other DIY CNC router offering?

The PrintNC Mini’s design makes use of rectangular steel beams which are interconnected with bolts to keep it DIY friendly.

It avoided all the shortcomings from entry level desktop CNC-routers that are on the market.

Such as the Indymill and Carbide 3D’s Nomad which are far less capable then the PrintNc

To name a few:

• Ballscrews on all axis
• Dual and triple ” Hiwin ” bearing block design
• rigid steel frame
• Supports watercooled 65mm spindle
• 3D-printed parts on the parts you can get away with less tensile strength
• Designed to mill non-ferrous materials

PrintNC Mini current status

The PrintNC mini is still in beta mode. Meaning it is only available to a select few which have purchased the 3D files and get access to the member zone. At this point approximately 2 or 3 completed builds were spotted on the Discord.

It is too early to know the full extents and capabilities of the PrintNC mini. But looking at how it was designed and the already excellent performance of the PrintNC DIY router, I have full confidence in it.

Looking for something completely different?

Have a look at my build the Mightymill :

Conclusion

The PrintNC mini is currently in Beta status and a few builds have shown up on the discord. The design carries many improvements from the PrintNC V3.0 and seems to have addressed the main issues with that design.

It is too early to know the full extents and capabilities of the PrintNC mini due to small amount of builds out there.

I’ll definitely be watching closely at how it performs over the coming few months.

What makes the PrintNC so special vs other offering?

The printNC’s design makes use of rectangular steel beams which are interconnected with bolts to keep it DIY friendly.

It avoided all the shortcomings from entry level desktop CNC-routers that are on the market.

Such as the Indymill which is far less capable then the PrintNc

To name a few:

• ballscrews on all axes
• powerful and heavy duty spindle (2,2kW water cooled spindle options)
• rigid steel frame
• 3D-printed parts on the parts you can get away with less tensile strength
• able to mill non ferrous metals with ease and steel to some extent

To put it briefly, it was the best entry level machine in the price to performance category i ever came across.
The only downside is the extensive time commitment required. You must build the framework for the project and set up everything yourself.

Resources

If you want to know if this is the right machine for you, check out all the available resources.

To name a few:

• Wiki of the printNC
• Discord (Very active, friendly and noob friendly)
• Fusion360 model
• PrintNC building playlist by Christoph Lehner – youtube
• PrintNC building playlist by Projects by Brian – youtube

What is the machine capable of

Fully flexible design

The machine concept is fully parametric. You can customize the build to your needed dimensions.
I mainly do sheets of wood so i wanted to be able to pass a full sheet through the machine. Therefore i increased my X-axis to a work area of over 1250mm.
Due to the size of my workshop the biggest dimensions i could get away with, was a footprint of 1600mm x 1000mm.
There is a calculator on the printNC website to calculate all your machine dimensions based on your work area. It even shows you which profiles, screws and other hardware you should get.

Essential parts

• Metal cutting G-penny CNC spindle kit 2.2KW 80MM – Tested and verified by PrintNC members
• High quality HGR20 / HGW20CC linear guides – HLTC – Verified and tested hundreds of builds
• High quality clean & debris free 16MM 10 C7 ballscrew – machined to length – verified by PrintNC
• G-Penny – Casted 80mm spindle holder PrintNC verified

Conclusion

While it takes some time investment to build a diy cnc router yourself, I must say personally it was worth it!

All in build cost are ~2000 USD and that offers you the most capable open source cnc router currently out there.