[duitmighselph]

Hey.
Old post, but I have similar problem.
Did you find out what was wrong with your CNC?

I would like to bump this thread too. Very curious. I have a similar situation.

[Goose80]

I did not find any problems with electronics.
But i think i had to much flex in my Z-Axis build, so when you mill a round hole the Z-axis gave up.
But this is just a theory.

I am building a new CNC now, with 100% Aluminium and Hiwin rails so i will see how accurate I will get it.

[duitmighselph]

Thanks for completing this thread. I am pleased to see the outcome. Good luck with your new build!

[FandZ]

Do people cut 2inch squares with .25 and smaller bits and get 2inch squares in wood? I've always seen a .005 variance with it getting larger as you get closer to the bottom due to tool flex. Climb vs conventional milling will either give you a smaller part or a bigger part. I've only seen near perfect measurements when cutting plastic or using bigger bits. Whenever I design interlocking wood parts I always give it a little extra space so things fit together.

[louieatienza]

Do people cut 2inch squares with .25 and smaller bits and get 2inch squares in wood? I've always seen a .005 variance with it getting larger as you get closer to the bottom due to tool flex. Climb vs conventional milling will either give you a smaller part or a bigger part. I've only seen near perfect measurements when cutting plastic or using bigger bits. Whenever I design interlocking wood parts I always give it a little extra space so things fit together.

I've mnot seen a .25" bit with a 2" flute! That said you should use the largest diameter and shortest tool possible that gets the job done. Period. I can't say how many times I've seen a video where someone is using a .125" end mill and it's stick out is over 1", and they're cutting 1/8" thick parts. The closer the collet to the workpiece the more rigid the tool.

[duitmighselph]

Do people cut 2inch squares with .25 and smaller bits and get 2inch squares in wood? I've always seen a .005 variance with it getting larger as you get closer to the bottom due to tool flex. Climb vs conventional milling will either give you a smaller part or a bigger part. I've only seen near perfect measurements when cutting plastic or using bigger bits. Whenever I design interlocking wood parts I always give it a little extra space so things fit together.

I have not been to my shop in a while. Sorry this test is so late, but here is my results of a 3 inch square. It makes me so sad.

[duitmighselph]

I have not been to my shop in a while. Sorry this test is so late, but here is my results of a 3 inch square. It makes me so sad.

It was cut with an 1/8 endmill. Two flute straight. 1/4 shank. Conventional tool path. 2 DOC's. 40 IPM.

[ger21]

Looks like you Y and X are not perpendicular by a few thousandths of an inch. So you'd need to make a small adjustment, if you can actually adjust something and move it .002".

Other than that, adjust your steps per inch to fine tune the distances.

[duitmighselph]

That's great insight, Ger. I was wondering about that. I saw a video a while back on youtube.com about a guy that was squaring his Y axis. I believe his name was "cuttingtooldesigner". I will go back and watch that video again and see if I can make the very fine adjustment. Ill try, at least. I will create another square after I have done this and re-post. I sure hope this thread will help some other newbies that may be reading it.

[duitmighselph]

Here is a link to the video...

https://www.youtube.com/watch?v=CVoU4zVPKZo

One caveat though, I will not be shimming to correct the error. I have limit switches at the end of my X rails. The limit switches are threaded barrels and have nuts on them. I can move them in and out as needed. I'm just not quite sure how he calculated that angle though. I should probably just do the procedure and get into a CAD program and then worry about that. The CAD program will likely have a measuring tool for that, anyway.

[duitmighselph]

Ok. I have now squared my gantry. It was off on the left rail by 0.016". I made the correction and tested it twice. The first test was "perfect", so I had to cut and test it again, because I did not believe it. lol. But, sure enough, the second test was "perfect" too :banana: I am so happy about that. I will cut another 3" square to see if there are any improvements in dimensions and accuracy.

[stripedtreads]

Hey.
Old post, but I have similar problem.
Did you find out what was wrong with your CNC?

We have found in the past when cutting up towards the top of the machine (left hand tools) that the gibs are loose or the turkite is worn out and the whole turret is lifting up when cutting make the part bigger and a bad finish. to check we put a long bar in a empty pocket and lifted on the turret and was able to move it 110 thou. replace the turkite and had it scraped in and is holding dimensions.