#46 Constants of CNC Accuracy Testing - Travel Accuracy Backlash Squareness Deflection Repeatability

[@MarionMakarewicz]

M00T 1 means that there will be a M00T 2! Yes, more CNC building. And your videos are never too long. Thanks for going over all these parameters. It is very helpful. Congrats on such a great build and have a Happy New Year!

[@EducatingSavvas]

I'm just opening myself up for more failed goals. Happy new year! 😁

[@chrisnurse6430]

I learn so much from your content - thank you

[@VHERSACNC]

Thanks for sharing this Savvas. Have a great new year😎

[@EducatingSavvas]

You too! 😁😁

[@JesseSchoch]

measuring diagonals works well but I don't think eyeballing a square is a good way to check the geometry of the machine. I'd strongly recommend you get a set of 2,4,6 blocks and use your dial indicator to measure the geometry vs just getting a notion of it. You will find the blocks generally handy for many many setups and measuring tasks. A indicator holder that mounts in your spindle is also very handy for tramming your spindle. You also may be seeing backlash in the ball screws based on the roller bearings they tend to come with. Tightening can't really take out the ball bearing slop unless you put a spacer in which will likely reduce the life of the ball bearings. 40 degree angular contact bearings in the FK12s will improve the rigidity over what you get from chinese FF,EF,BF supports. It may also be a good idea to validate the squareness of the machined nuts since I've seen firsthand that they are not always actually properly machined.

[@EducatingSavvas]

A lot of what I'm going to make only needs to be validated by my poor judgement and bad eyesight. It was more important for me to get the x and y square, and the z to be passable. But yes you can even make a simple jig with a machine screw held off from the spindle and use paper (old fashion invention) to check the gap between sides. I did that once with a drill press table. If I was building these as a job I'd make jigs to calibrate all the assemblies but instead I just use a kitchen granite work-surface. The backlash on the ball screws is 0.05mm once the locking nut is properly tighten, which I can live with. I'm not well versed with how to use blocks though - I'm not an engineer so really making it up as I go along. I wanted this video to highlight areas to look at for people starting off really. Cheers and happy accurate new years.

[@JesseSchoch]

@@EducatingSavvas The blocks are really handy and easy to use since they are square and parallel to .0006". The setup for this is simply setting the block on edge, attaching your dial indicator to your Z axis and setting it up on the side of the block. The blocks have quite a lot of heft so they stay put. You then just move your Z up and note how much your indicator moves. Since they are perpendicular you get a direct measurement of your z perpendicularity. The blocks also have threaded holes so you can bolt directly to them. This is great for workholding and where they can really shine. Since I have a bunch of 123 blocks and one set of 246 blocks I don't think I could live without them. The metric equivalent are 50-100-150 blocks. Setting this up for your machine would literally take less than 2 minutes. I also point it out because they are a tool every cnc or mill should have. My set was $64USD but the price has gone up a bit. An alternative might be using a set of parallels and setting them up perpendicular. Oxtools has a video on how to do this easily.

[@EducatingSavvas]

​@@JesseSchoch I don't want to over-complicate this but I sort took your advice - I took off the z assembly with the newer mounts and used the granite kitchen work-surface, an engineers straight edge and dial gauge to check the plate against the rails / ball screw. Which I got down from 0.16 to 0.06mm off. I then flipped the assembly and clamped the straight edge to the spindle mount with the spindle in place and made sure those were tightened in line with the plate - the top and bottom of the plate were less than 0.05mm off. I then flipped the assembly again and measured with the engineers square in the first position but this time the shaft of the tool in the collet. This was 0.03mm off over 30mm of the tool shaft length. I can now refit the tool and measure from the side of the assembly and free pretty confident the collet is in line. That's for the X axis - I've not thought about along the Y axis.

[@JesseSchoch]

@@EducatingSavvas I hope measuring it made it a bit easier to make the adjustments (knowing if you improved it and how much)! Now I just hope your square is square! I'm refitting a mill right now and it can be daunting to fiddle with all the small details.

[@EducatingSavvas]

Think I just got a bit lazy at the end. Lol. You can see the details here: instagram.com/p/B606SUDAH6X/?igshid=qb68xslt9rr7 - It's daunting to think about how I'll explain these steps in the manual - there's so many parts. Good luck with your refit.

[@buddhichampika5823]

happy new year savvas

[@EducatingSavvas]

You too! 😁

[@claudekim7876]

Have you seen the one marco reps made? That ones crazzzzzy accurate.. then again the milling head alone probs costed more than your entire setup. Overall i like this more than the other cnc you built.

[@EducatingSavvas]

His one is amazing, but he also came to a lot of conclusions that I had which made me go for a smaller simpler design.

[@UberAlphaSirus]

Good results.

[@EducatingSavvas]

Not good enough! This cheese needs to be perfect!

[@iTheEncounter]

So what’s the final testing results for accuracy ?

[@EducatingSavvas]

On the cut it's about 0.3 of a millimetre backlash. I'm in the middle of rebuilding my controller at the moment, and will make better videos about it's capabilities but I'm really happy with my machine. It's a little heavier than I had liked but got really good results whenever I needed to cut anything.

[@genkidama7385]

guess why professional cnc machines are big

[@Seed-qj6jk]

Hi mate, could I use some of this footage in my kickstarter project?

[@EducatingSavvas]

No, please don't.

[@Seed-qj6jk]

@@EducatingSavvas not even the part between 5:35 and 5:38?

[@EducatingSavvas]

You haven't even told what me you're trying to do a Kickstarter for... so the answer is no.

[@Seed-qj6jk]

@@EducatingSavvas I'm making a CNC machine, how come you don't want me to use it?

[@EducatingSavvas]

Any formal request should be emailed through the contact section - with your name and contact details. It's very unprofessional to do this through the comments on a video. I'm also reluctant to allow my footage to be used, especially on Kickstarter considering I didn't crowed fund my CNC machine. Answer is still no btw.

[@aamaya13]

*Deflection exist* Oh, we built this machine one rollers....