EPIC CNC upgrade - episode 2. part 2 assembly and fine tuning 

Bob Ross: Happy Accident Fox Wysocki: Good Fuck-up

It's difficult bolting things with countersunk screws because the order in which you tighten them affects the alignment. Even the concentricity of the screws may affect the outcome. A small drop super-glue cynoacrylate may keep parts from shifting when clamped : ) It's bond can usually be broken with a mallet. I've used glue-gun glue to hold two parts so they can be drilled to be tapped, but aluminum pulls the heat from it pretty quick, so the bond is light. I am a similar coupler on my CNC (which I finally got moved to were I can use it.) The orange-polyurethane is little strange but it seems to work. I wish it had one more screw on the pinch-bolt. When you pointed out the bend in the ballscrew it reminding me of this extreme setup they used to limit the non-axial effects. If I make a machine as precise as yours, I may use that technique. There's a video on my channel about the "1 micron axis." I won't post a link. This is your channel. I guess, if you wanted to get pedantic, you could put the far end ballscrew mount on linear ways, so as the ballscrew stretches, it won't bow. On my CNC, the parts came with one pair of angular contact bearings on one end--and one radial bearing with a sliding fit on the other. I should grease the other end, now that I think of it. Excessively Neat stuff! Cool project!

Jesteś moim mistrzem i kimś na kim mogę się wzorować budując swoją frezarkę CNC. Dziękuję za pomoc :)

Thanks for going into details in your videos. It's very interesting to follow along with your thinking on tolerances and compounding errors - what matters and what doesn't. :)

Hello Piotr, outstanding work on your machine! I've been inspired to change my design from fixed to moving gantry, using your approach with granite! I'm desiging the machine but I'm not sure how did you setup the control part: I see you're using now AC servos, but how do you drive them? Do you have a servo drive for each motor? does the servo drives communicate with the motion control box? Could you provide more details about your controller box? Thank you very much in advance and keep up the good work!

Nice to see you again. Very useful information for me, because i try to make my own cnc mill, but with epoxy granite. Maybe i will film it, but as you know, filming and making - it's very long ) Thank you!

I use a torque wrench when tightening the locking screws on jaw couplings - most come with a torque spec for this and you really don't want to mess up the threads by overtightening

Look into "Bonderite" or "Alodine" for priming/protecting aluminum, whether or not it's going to be painted.

Hello Poitr, Great machine build. I saw your screw setup and had an idea and question. I see the structure is like a C-channel and is very rigid. I also notice you mount your bearings with 90° angle brackets. If you think it would be a benefit... You could mount your bearings with a flange to the end of your C-channel structure. (no angle brackets, just flat plate for the bearings. This way, you could add tension to the ball screws, and your C-channel structure would be in compression, and take the force perfectly and not bend. Is there an advantage to a tensioned ball screw ? Maybe. I know they do this with very long and high speed ball screws to reduce whip. It just seems if you redesign your brackets into plates, the potential to apply load in pure compression, and not bending could be a benefit. It seems you fancy the concept for modular components that can be had from the catalogue, but plates that I am suggesting are a quite simple machined part. So, no criticism of what you have in any way, just an idea for making a more rigid drive system, from an engineering point of view. You have 90% of what you need right now. Keep up the fine work. --Doozer

Piotr... I highly recommend wrapping the exposed metal with masking tape to prevent sparks (molten metal) sticking to any precision surface.

thanks for sharing Piotr. Question: Are these units going on your Granite CNC mill? If so where?

Dumb question - I am considering building a small desktop CNC and I am curious about using Chinese linear rails because I do not plan on using the machine to make a living. Are the Chinese Linear Rails just not as heavy duty as your new rails or are they worn out or were they crap to begin with? (Are they at all worth it or should I steer clear entirely?)

hey Piotr, me again! i know a detailed video is coming eventually, but could i ask you a few questions about the motors you're using please? did they send you the 400W or 750W kit? i don't think you mentioned it! i'm trying to decide between cheaper integrated DC servo motors and the AC servo kit from motioncontrol you're using. am i correct in saying that the AC servos are powered directly by mains AC, through a breaker board, meaning i don't need any additional power supply or rectifiers? because if so, the additional 4 DC power supplies certainly reduce the difference in price.

Hi Piotr, Good job! Probably anodizing could be a better way to paint it.

When this thing is finished Its going to look soo sleak. But the cut quality and precision might overshadow how good it looks. Have you tried milling stainless on it? I've only seen you mill aluminum.

Piotr, hi. Did u try threadmilling on your cnc?

Hi ! BK support should be used on the motor side. Why are you using BF support ?

Did you flatten that aluminum before bolting it all together - or is it just as flat as it was from the factory?

I’m surprised you cut the ballscrew shaft rather than making an extension plate for putting between the motor and the mount.

epic as always

use oleiс acid while making screw - it'll make it perfect, mirror-smooth and easy.

i believe you could buy an aluminum U channel. that is essentially what you build here.

Cast iron to process, IMHO. Or cut the rails from a single piece of iron. Or propellers for marine vessels. Not?

That style of shaft coupling is bad for precision applications, as it is torsionally flexible. It's made for absorbing shock loads, not positioning accuracy. You want the metal bellows, single piece flexure or disc flexure type. Everything else looks great. EDIT: I did some research and it appears that I was wrong.

Really nice updates to your machine! I just documented the build of my CNC Milling Machine in a video - you might enjoy watching it :)

Cool!

Wo hoo , first , Hi Fox ! =D