CNC Machine Survey using a Ball Bar

[@tracylemme1375]

Working for a major defense contractor, I purchased a Ball Bar system about 15 years ago(no Bluetooth) . In less than 2 months it paid for itself. By using the ball bar once per year we can predict failures and schedule maintenance. Every machine has a history of ball bar runs. It is one of the most valuable tools in the shop.

[@govindarajd3248]

Thanks! I'm a mechanical engineering student and I found this incredibly helpful! Excellent narration and production quality!

[@jbrownson]

incredible series, especially loved this one, thanks

[@Steve_Just_Steve]

Yet another excellent video Tim. Very interesting to get that great breakdown of the ball bar plots and congrats on the excellent results! Under a thou on a 15 -20 year old Fadal is really great and it has to be pretty rewarding to affirm the accuracy that resulted from all the work you put in to dialing that ol girl in. Great job!

[@AtManUnlimitedMachining]

Thanks Steve, yeah, pretty cool when that first plot came up and it was that good. Still could be even better. Might be able to get it down to 5 or 6 tenths if I really work hard and maybe get a new Y screw. But I really don't need to so I'm going to call it good enough! It is fun sharing with everyone and helping people out.

[@christurley391]

Never saw that test done. Informative thanks for the lesson.

[@AtManUnlimitedMachining]

Your Welcome Chris, thanks for watching! Hoping to do a video on the Laser at some point.

[@unionse7en]

The ball bars functioning principals are truly elegant!

[@AtManUnlimitedMachining]

Yes, simple and to the point

[@frankrizzo5583]

Very cool! I've also seen circular coupons cut as a cheaper alternative when you can sneak a part onto a cmm

[@AtManUnlimitedMachining]

Yes, you don't even need CMM sometimes. If you cut a circle and then come up a little and cut it the opposite direction you can see edges show up with different errors.

[@NerdlyCNC]

Awesome video

[@AtManUnlimitedMachining]

Thank you

[@harrisonaero]

Nice job- really like this channel. Keep it up :)

[@cofranariel]

amazing amount of information

[@AtManUnlimitedMachining]

Thanks

[@kiranbhangale6600]

Very good explanation

[@scottcase6708]

I have worked with Brian! He tuned our Mazak HCN500 to less than 0.0002" circularity on the barbell (haha) and laserd all th eaxes as well. He knows his S&*%#

[@jdaz5462]

Cool stuff. That ball bar setup is only $8800 on MSC :)

[@AtManUnlimitedMachining]

Not cheap, but there are a lot of calibration service companies that will come on site and do it for a "reasonable" cost.

[@salvadordiaz3369]

Question which steps should I follow in the sv command to load the data of the card into the ram and how should I placate the current normal or maximum normal gain

[@AtManUnlimitedMachining]

The values will get loaded into ram on first power up, and then any time you change them the machine will do a hard reboot and you will need to cold start it again. I think there is also an option to read them directly from the card in the SV command but I would need to look at it again.

[@salvadordiaz3369]

If there is a way to view and modify the sv command of what I am not very sure is if that command serves me to correct the error when machining a circle

[@AtManUnlimitedMachining]

The SV command will allow you to change the ball screw survey. But you need to measure the machine to know what to change it to. Also, the ball screw pitch comp is just one of many sources of errors that can cause bad circularity.

[@salvadordiaz3369]

In advance many thanks for your help I may send you a video so that I can explain well because I have 2 problems one in the perpanticularity of z with the xy axis and the other in orbit

[@AtManUnlimitedMachining]

If Z is out of square that could be just a level adjustment depending on what machine and how many feet it has.

[@NerdlyCNC]

pretty awesome video

[@AtManUnlimitedMachining]

Thanks Jay, I saw your video on finding the ball bar data on the Haas. Unfortunately that report is just one tiny value of what the ball bar provides as you see in this video. Two things I noticed as well, they only ran an 8" circle on a machine with a Y travel of 16". Seconded, they did not run a full circle on the Z plots, just a 180 like I did. Feel free to drop an email if you have any questions.

[@NerdlyCNC]

will do. i wish my report had all the data like your did....also i'd like to know if the test was done before or after any backlash compensation.

[@AtManUnlimitedMachining]

From what I understand (this is opinion and not fact, it could be wrong) is that they run the ball bar last before it ships. If you can find or get a hold of the .b5r file I can load it up and get the rest of the numbers out of it.

[@NerdlyCNC]

I'll look for it

[@crashwrench]

Hi , Wow Brian Can Speak ! I Would have to liked to Have herd His thoughts on what his Result's Found on your machine . What He Would Recommend to make the necessary Adjustments to Improve The Tolerances . Thank you :)

[@AtManUnlimitedMachining]

He is a private guy. We keep improving on the machine, but it is getting to the point of little return. The next big item is the Y linear rails.

[@voodoovinyl434]

Thanks! Love these Vids!

[@AtManUnlimitedMachining]

Thank you

[@TeslaAtoms]

@@AtManUnlimitedMachining Very cool How much are those ballbar systems, are there any affordable systems out there? Only one i know is renishaw, but they charge like 11k for a system.

[@tedshred9285]

Great explanation. Anyone have this done? Trying to figure a ballpark price for someone coming in to do the test; we are moving later this year, have approx (30) CNC's to move. Thinking the ball bar test would be a good way to prove equivalency before & after the move...trying to avoid all of our customers demanding first piece reports.

[@tedshred9285]

oops, just saw the same question below from ducks2525. How many can a decent tech do in a day?

[@AtManUnlimitedMachining]

Takes me about 2 hours to do XY 360 and ZX YX 180

[@spkrman15]

that was really cool! could some of the error be mechanical? are you using servo motor parameters to compensate?

[@AtManUnlimitedMachining]

Yes, about 50% of the error is mechanical from various sources. The only things you can comp out is backlash and ball screw gain on this machine. Other machines you can comp out way more stuff. High end machines will let you comp out straightness errors by moving the Y some if X is not straight.

[@projectgt3rss]

Excellent video! One question though; how is the bar held on the spindle side? If the pivot point is off axis with the spindle axis, isn't that going to throw everything? I was kind of surprised to see what appears to be a drill chuck holding the cup. Cheers!

[@AtManUnlimitedMachining]

Hello Nico The spindle does not turn during the sweep. That will eliminate the need for any alignment of the spindle axis. The spindle is just acting as a holding point. The bar rides on a ball with 3 brass fingers to keep the mounting point accurate during the sweep. That is why using a drill chuck is ok to do.

[@multiHappyHacker]

I wonder if a centroid retrofit with new servos could do better than that?

[@AtManUnlimitedMachining]

I have a calmotion upgrade and it is a little better. I looked at Centroid but the install required new everything and basically gutting the cabinet. The Calmotion upgrade is a simple plugin that takes less then a hour in most cases.

[@multiHappyHacker]

@@AtManUnlimitedMachining What are the prospects of buying an old Okuma with a low memory control and no DNC ability, then putting a new control on it? Retrofit with new control seems pretty rare on other machines.

[@AtManUnlimitedMachining]

@@multiHappyHacker You can do it, but is it cost effective? That is what it comes down to, can you get the parts and how much will it cost vs buying something newer.

[@sellenger]

Been waiting for this one for a while !! So backlash software comp, is this just a parameter in your controller ? Does the ballbar give you an exact value to enter or is there some playing around with it ?

[@AtManUnlimitedMachining]

Hi Drew, there where a few people waiting for this one. I had to get the Z ball screw done first though. The ball bar will give you the exact amount of backlash it measured. You then add that to the value currently in the machine. It got us within a tenth on the first try, we added one more tenth and ran one more time.

[@motorbreath22]

Loved the intro

[@AtManUnlimitedMachining]

Thanks, try to keep it interesting

[@davestrong6472]

Your best video yet, considering your machine is 25 years old pretty respectable. The take away is best tolerance are at 20 rpm, I wonder how the machine wound handle 50, 60 or 100 rpm. What's a test like this cost?

[@AtManUnlimitedMachining]

Thanks Dave, trying to get them better. The feed rate effects the following error and mismatch of the servo drives. The faster you go the more error you will get. The slower you go the better it will get to a point. With the older analog machines they start to fall apart around 50 IPM. When I rough at 100 IPM I leave about 0.01" of material on the part to account for the errors. Most services will charge out at an hourly rate. It takes a few hours to setup, run, and clean up. So your looking at a couple hundred bucks for a basic check. The laser is a lot more because it takes a lot longer to complete.

[@SmallShopConcepts]

+At-Man Unlimited Machining interesting, is it considered better to run servos in step direction mode rather than analog for better accuracy then?

[@AtManUnlimitedMachining]

Typically your not going to see a step/direction setup in a machine with Servos. It is very machine dependent and where the position loop is closed. Some machines the drives just close the motor velocity loop and the position loop is in the controller (fadal is like this) other machines close the position loop in the servo drive as well. Either way, most drives will use either an analog voltage that represents the velocity or position set point; OR they will use a digital communications bus to send the numeric value. This is better because rather then go through s D/A, long wires, then A/D you keep that number digital so there is no noise or calibration issues of an analog signal.

[@ThomasShue]

The bar ball system I saw was $10,000+. It was not cheap

[@makex_se]

A true machinist uses this to practise maching circles on his manual mill ;D

[@DUCKS2525]

What does it cost to get a ball bar test done?

[@AtManUnlimitedMachining]

The basic survey takes a hour or two, so typically a couple hundred bucks.

[@DUCKS2525]

Not Bad! Thanks and thanks for the video's! Keep up the good work!

[@AtManUnlimitedMachining]

Welcome, it is a good investment to know where your machine stands. Helps when a customer calls and asks, can you hold XXX?

[@edwardhorton7029]

you should be testing at the feedrate you run at.

[@AtManUnlimitedMachining]

Correct, my average finishing feed rate is 40 IPM

[@mythril4]

I am going to have the guys at fadalcnc.com stop by and ballbar mine, they are only 3 miles from me, I learned they are awesome people in person.

[@jtena7902]

aaahhhggg, you grab the spindle with a drill holder¡¡¡ That is very bad

[@AtManUnlimitedMachining]

Why do you think that is very bad?