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Mightymill – Build log #2 -professional diy CNC router

The Mightymill is the name I gave my professional DIY cnc router build that I’m working on. It features IHSV57 servo motors, BT30 ATC CNC spindle, Durfill polymer concrete filling and more.

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.

The heavy duty z-axis

Due to wanting to use a BT30 ATC spindle I had to upgrade to a heavy duty Z-axis. The design I opted for was originally designed by Crabs Shed. I optimized some small aspects of it and added it to my design.

heavy duty z-axis cnc machine design
Fusion360 image of the heavy duty z-axis

Milling the z-axis plates

Crabs Shed was so kind to help me with milling the z-axis plates for my diy cnc build.

He even made a video of him milling it:

Crab shed – milling z-axis

Initial measurements

heavy duty z-axis diy cnc router image
Measuring rail deviation vs eachother

One of the first things I did after receiving the plates was mounting my Sorotec Blue line HGR20 rails to it and measuring the (relative) flatness of the base plate versus it.

I quickly noticed that the leftover milling marks had a significant impact on the relative flatness of the mounting surface.

As the rails I uses are P – grade and my carriages have p1 preload it adds additional requirements on the rail mounting surfaces and alignment versus each other.

linear rail hgr20 mounting surface diy cnc router uhpc 8020 t-slot
Excerpt from Hiwin linear rails assembly document

The image above gives you an indication regarding the accuracy of various parts of the rail and the various grades available. Regular Aliexpress “china” rails will be grade C or worse undefined.

I measured too much deviation of the z-axis mounting plate for my liking. I really wanted to keep this under 0.01mm or better hence I had to take it one step further.

Surface correction step #1

I got myself a set of whetstones from aliexpress in order to get rid of the milling marks and achier an overall surface which is more uniform.

In terms of improving the surface finish and flatness this did the most. It removed all the high spots and made the surface much more even.

Whetstone set

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

harpening Stone Professional Grinding Stone Set for Knives, Double Sided Grain 400/1000 and 3000/8000, with Bamboo Base, Angle Guide
diy cnc z-axis flat whetstone
Surface quality after initial step of making the surface more ven.

Surface correction step #2

I got myself a small and affordable granite surface plate. It came with a full test certificate and all.

Surface plate cheap eu 000 grade A 1.2um
Test certificate of surface plate

I got this since i wanted to scrape the high spots of the mounting surfaces flat.

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

Gedore 133 F-200mm HSS scraper [USA] [DE]
Diamant bluing paste – Tuschierpaste [DE]
Rubber brayer roller [USA] [DE]
Items I used for surface scraping the alu z-axis plate

In total I spent about 2 hours of scraping. Can significantly speed it up if your initial plate is flatter or if you use power tools such as a dremel to do the difficult work for you.

surface scraping aluminium z-axis diy cnc
After scraping bottom mounting plate
surface scraping aluminium z-axis diy cnc
After scraping top mounting plate

I was not completely happy about the Diamant bluing paste. When indents get smaller than 0.01mm you will have a very hard time seeing it. There are better alternatives out there albeit those are difficult to get as an European.

When fully assembled, I measured the parallelity of the top plate vs the mounting surface of the Z-axis and it is well below 0.01mm. Good enough for me!

Mounting the Lusintun ATC spindle

Time to start drilling holes in the 100mm spindle mount.

100mm spindle holder drill hole BF25
Drilling holes in the 100mm spindle mount

The spindle mount was too tall so I could not fit a bigger size drill in my BF25L. So i had to put it on the side and ream it to the final size of 8.5mm.

100mm spindle holder drill hole BF25
Manually drill to final size of 8.5mm
100mm spindle mount lusintun BT30 atc cnc spindle diy z-axis heavy duty z-axis
Semi-assembled heavy duty z-axis

How heavy is the Z-axis?

100mm spindle mount lusintun BT30 atc cnc spindle diy z-axis heavy duty z-axis weight 25kg
Z-axis weight measurement 25.4kg

I would have guessed that it would have been heavier but 25.4kg it is!

New goodies

As I’m still waiting on quite a few milled parts for my cnc build I put my focus a bit on other aspects of the build.

HGR20 linear rails covers

To protect my nice precision and preloaded linear rails I know that I needed to get myself some linear rail protection. After looking on Aliexpress I found myself some.

HGR 20 rail cover aliexpress
HGR 20 rail cover aliexpress
20221005 124321

I got 6 of the 600mm length ones. This is probably a bit too long for my build but I was afraid to get ones which were too short. It has many “internal supports”. This enables you to cut it to size when needed. You can find them here on Aliexpress.

Tool length measurement

In addition to that my tool length measurement sensor just came in. It seems like quite a solid and professional item. I also made a separate review of it. For those interested you can find it here.

Finishing up the machine frame

As I had too little concret last time, I went to Hornbach, got some more and finished up the second leg of the machine frame.

20221008 154653

I cut some extra holes in the legs as I wanted to make sure it was completely filled.

After grinding it open I observed that it was completely filled. So there is no need for doing this. the total weight of a single concrete filled leg is 120kg now.

Mounting for the machine feet

I started cutting some 120x120mm squares out of 10mm thick steel plate to have a surface to mount my GD-60 levelling feet to.

angle grinder cut 10mm steel diy cnc
cutting out steel plates with angle grinder

After cutting and tapping it was time to grind off some paint from the legs and weld them to the frame. It made a little mess of my previously beautifully painted kern red paint.

weld steel plate machine leg table diy cnc
router concrete
Steel feet after welding mounting plate to it

I will have to clean up the spatter a bit and re-paint the damaged parts.

painted machine frame kern red concrete uhpc
Re-painted the machine leg

Conclusion – Mightymill build Part #2

Getting the z-axis mounting surfaces flat and dialed in was initially one of my bigger concerns. But after wet sanding it and scraping I was quite happy with the result.

Additionally I was able to make some progress regarding the machine frame.

Now it is finally ready to go to the next step and that is mounting and aligning the alu extrusions and rails to each other. And start making my design into reality.

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Feel free to reach out to me on discord

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Hi, My name Is spikee and I'm the Author of this post.
I have been active on various cnc communities over the past few years.

On this website I share tips&tricks, reviews and intresting resources relating to diy cnc and cnc router topics.

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