Building a Portal CNC Milling Machine from Scratch - 1

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DIY/ “Homemade“ Portal Milling Machine with automatic tool changer spindle SK30 (BT30). The overall working area of the machine will be about 550 x 650 x 450 mm (X x Y x Z). The total weight will be about 950 kg. The structure of the machine is a welded metal frame that will be filled with UHP concrete to improve the dampening. All the components of the machine (ball srews, linear rails, ...) are industrial grade (Bosch Rexroth, THK, SKF, GMT, ...). The machine will be power by NEMA 34 stepper motors for testing. Until everything is working as expected, those will be substituted by a servo drive system complemented by SICK absolute encoders on all axes.
The build and component purchasing started in 2016, since then we were able to get basically everything together that‘s needed to finalize the build.
The milling spindle is a spare part from an old (1990) Steinel BT20 5-axis milling machine
Some Specs of the Machine:
- X Travel: 550 mm
- Y Travel: 650 mm
- Z Travel: 450 mm
- max. G0 (X,Y) : 15 m/min
- max. G0 (Z) : 10 m/min
- Servo Power (later) : 400 W (max.)
- Spindle Power : 4,5 kW (i = 2.5)
- Tool Holders: SK30
- total weight: about 950 kg
- outer dimensions: 1000x1200x1200 mm (without housing and table)

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Опубликовано:

6 мар 2021

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Комментарии : 31

@keezo1234 3 года назад

This is so sick

@TrPrecisionMachining 3 года назад

very good proyect..thanks for your time

@EngineeringSpareTime 3 года назад

Thank you :)

@nickp4793 3 года назад

Wow! Great work!!!

@RUNCNC 3 года назад

I like your design! Very similar to mine. Don't forget to heat treat the weldet parts.

@EngineeringSpareTime 3 года назад

Thanks! Nice machine you got there :) That’s a good point. Unfortunately we didn’t had the chance to do this. We heated the whole structure up before welding, to reduce the deformation a bit. The time in the workshop - we were allowed to use back then - was limited to two days, so we had to hurry a bit..

@xyzspec82 Год назад

I need to see this beauty cutting, please 🙌🏻🙌🏻

@EngineeringSpareTime Год назад

I’m currently working one this!

@soncnc Год назад

tuyệt vời 10 điểm

@jonassantos4763 3 года назад

their machines are definitely not homemade! Amazing!!

@EngineeringSpareTime 3 года назад

This one machine is “partly-homemade“ that’s right :)

@Saya1418. 3 месяца назад

Make it open source ❤

@vnuendru1 2 года назад

Hi, awesome projects! Why you decide to build new cnc, something wrong with previous one? Or you decided to build just a bigger one? If so why portal design instead of vertical ?

@EngineeringSpareTime 2 года назад

Hi, thank you! Yes, the main reason is the effective working area. In addition to this, this machine is more powerful what allows bigger cuts on bigger parts. It’s a portal design because of the better ratio of working area to machine footprint and this setup allows it to extend the Y-axis (through the portal) for long parts if needed.

@vnuendru1 2 года назад

@@EngineeringSpareTime is portal design more rigid in your opinion? Also why not just fully cast with uhpc? And don't you think z axis is less rigid in portal design than in vertical?

@icadcamedu 3 года назад

bro can you share the manufacturing details of the iso 20 spindle that you made before? (cad files o blue drawings)

@EngineeringSpareTime 3 года назад

I plan to make a video about it, this will take some time though :)

@icodirtjumper 3 года назад

Really impressive!! Are you really a student? I studied in Germany as well(University of Stuttgart) and none of us were so advanced even by the end of our studies!Major congrats and good luck!

@EngineeringSpareTime 3 года назад

Thank you, I appreciate it! Yep, I‘m doing my masters right now :) I‘m interested in engineering and building stuff for more then half of my life, my university studying complements what I‘ve experienced before and allows me to understand and thus further enhance it. The theoretical study can not stand alone, the more one is experimenting, trying and failing the better gets the understanding where to put this theoretical knowledge and how to combine it. This is at least what I think is the fascinating thing about engineering or learning in general :) Universities alone can unfortunately only offer this to a limited extent..

@pmsilvei Год назад

More please? 🙂

@user-zy2qn1nc9y 3 года назад

Since UHPC isn’t increasing thermal stability neither rigidly to you welded frame why not filling with lose sand? It will increase the damper many times more than concrete because sand as discontinued material will convert movement into heat.

@EngineeringSpareTime 3 года назад

I planed to use UHPC due to my good experiences with it in earlier builds. I played with the idea of filling it with sand (hear about it been used in casted frames), I just don‘t now how it is going to perform - never did it before. Do you have experience with this or maybe a paper about the effect of sand as damper in a machine frame? This would be appreciated. Thanks for your comment!

@joansparky4439 3 года назад

-Did you heat treat the welded assemblies before having them milled to relief welding stresses and thus distortions?- What are your theoretical deflections in N/um at the tip of the tool compared to what you get in real life? What size are your ball screws (dia, pitch) and linear rails? Are you going to compensate the Z-axis with counter weights or pneumatic cylinders? What controller are you going to use? Thx

@EngineeringSpareTime 3 года назад

Thanks for your questions - I have not measured the actual deflection since the spindle housing is not finished jet. The theoretical deflections are difficult to determine especially the dynamic deflection, because modeling the UHPC core in the steel profiles is not really accurate. I will put it in the next video about this machine. - Dia of the ball screws is 48mm and 10mm pitch in Z, 40 P10 in X and Y 25 P8 (for now). Grounded and with the highest preload from Bosch rexroth -> from an industry sale.. - Yes, exactly. There will be a Pneumatic weight compensation. - It will be controlled by Linux CNC and mesa cards

@user-zy2qn1nc9y 3 года назад

Counterweight makes sense if the mass of the slide is above 1000kg, if less let the weight play in your favor to reduce inversion inaccuracies

@EngineeringSpareTime 3 года назад

I didn‘t want to go with counter weights since the Z-slide isn’t too heavy and this would increase the inertia. Yes, counter weights just in case the gravitational force due to the slide mass exceeds the expected cutting forces in z by far, in this case you‘d have to lift unnecessary weight most of the time that can‘t be used “potentially“ for cutting. The motivation of the pneumatic system was to avoid the slide to fall down in case of power out. For now I don’t have a break on the z-axis motor. And its not to difficult to integrate

@KamalSingh-ny9vw 3 года назад

Show some more photos and videos of the working machine.

@EngineeringSpareTime 3 года назад

I’m still working on it. It’s not finished yet :)

@Wheel333 3 года назад

🙏❤️🙏

@melansonjm 3 года назад

I don't understand why you chose such flimsy material. Aren't you afraid a small breeze might blow it down? Just joking! I have never seen anyone make anything look so rock solid! Well done!

@EngineeringSpareTime 3 года назад

Not recommended for outdoor use anyway :D Thanks, it should hold up quite a bit. We could get our hands on those components (linear rails, ball screws..) and as you might have noticed they are more on the heavy side for such a comparable “small“ machine, so the machine had to be designed accordingly :) The spindle cartridge is capable too, just imagine: this is just the spindle bearing arrangement, 12 kN of draw bar pulling force :)