CNC Router Accuracy & Backlash
HTML-код
- Опубликовано: 25 авг 2020
- The Y-Axis of my router showed a small amount of backlash from the standard deep grove ball bearing. I decided to change the bearing out for a double row angular contact ball bearing. It is still a compromise but it will fit without doing any modifications to the bearing block.
Наука
Very creative “sled” backlash illustration! Fast-forward with music works great. Such talent!
Thank you for your feedback !!
Do you use double ball nut bearing ? Am not sure that this backlasch test show correct. think that you should move the smallest movement possible forward and the the same backward and look at you DRO, and the slowly increase the movement. Also i think that your bracket for the steppermotor and bearing look a little flimsy i would have at profile going all the way to the other stepper motor and profile could be a 60x60mm
Lars, thanks dir your comment. Yes, a plate from side to side is an idea that I am thinking about since a while. It could also have the feet of the machine integrated. The “flimsy” bracket is 22mm think however so I think adequate. Measuring backlash the distance you travel will not be relevant it is the reversal of the movement that is of interest and where the “play” in the mechanics will how up. Also adding some speed / acceleration to the movement will really show what is going on. Give it a try the way I explained it and see. And then use your method in comparison. Compare the values the larger backlash measurement is the better method.
Hi I love You video , im looking to buy first CNC i think about 3040 can you recommend any?? did You build your from scratch or you bought and then upgrade. Best regards
I bought a kit that I had to assemble myself. However the vendor does not exist anymore. Also I have changed a lot on my machine. If you buy a machine think of the maximum size of your Projekts and purchase that size. Once you have it you can machine your own pets from aluminum to further upgrade it. I very much recommend linear rails and ball screws for your machine.
I really like the way your machine is built!! Can you recommend a place where I can purchase motion control parts such as ball screws or bearing blocks, etc.. There are plenty on the web but I want to shop a site that will assist and help me and have good quality products. On your router, as you've shown, its relatively easy to replace bearings or even the entire screw assembly and on my machine you have to lift the entire machine and or remove the bed surface to be able to work accurately. Any help much appreciated. Helpful video!!
Thanks, Peter
Hi Peter, thank you for your comment. There are a few places that I buy frequently from. High on my list is Misumi, for profiles and linear motion components. Also on Aliexpress use the seller BST Automation you can be sure to receive original HIWIN components. For motors I use lately 180W Nema 23 servo motors from OMC-Stepperonline. I will have a video about tuning them. For cutting tools I am a bit spoiled as I am past the point of breaking them by accident (… frequently). So Amana Tools, Datron, AluPower and YG1 are my go to cutting tool brands. Yes, picking up the whole machine to do some work would be a problem.
@@JBWorx Thank you, always appreciate your time and getting back to me.
Is backlash make big problem with servo motor planetary gearbox in cnc router wood machine? (because all planetary gearbox has backlash)
There are planetary gears that have no backlash but they are really expensive. Yes it can make for some Oszillation however you can set a filter to lower that vibration. Or make the tuning a little softer and it will work just fine.
@@JBWorx thanks for sharing your knowledge
Super! Wann kommt das nächste?👍
Kommt bestimmt ...
Nice video. I wonder how much of that backlash was from that sprung coupling you swapped out.
Kind regards,
Reuben
Thanks for your comment, I was able to remove also the software backlash compensation, in combination the bearing and coupler got me to zero backlash with no load on the axis. How this would look like with actual cutting forces applied is an interesting thought
@@JBWorx glad to hear it!
@@ReubenSchoots so today I machined a pocket 60x60 into the side piece of the new gantry. I was shocked the measured dimension was 60.00 x 60.01mm I am very pleased with that result.
I'm totally lost on why a bearing is causing backlash. I thought it was all in the nut.
Most bearings have axial play so the entire ball screw will slightly move forward and backward in the direction of the axis. Changing the type of bearing and eliminating that play will reduce or completely eliminate the backlash.
Did that last measurement really show backlash? It seemed to me that it only gave repeatability because you only approached the zero point from one direction.
I think it did because the original move of the axis was onto the dial indicator and I then set it to zero. Also that move was now focus on bringing the mass of the gantry into play so that the bearing really has to hold the position with a load like we would see in regular production.
@@JBWorx I always distrust unloaded movement measurements. They don't represent real life where the tool will be forcing onto s piece of metal.
I am with you on that. So I calculated the cutting forces on the largest bit I use being half way dull in Aluminium. It comes out to a load of under 160N not all that much … but now I started cutting steel 😀
The backlash is the free play between both negative and positive movement. You just check one direction. Backlash example; set the indicator to zero position then move -5 and stop. Then move +5 and stop. Finally move 0 again. Check the indicator to see your exact backlash.
I think we are saying the same thing what I did not show is that I made a move toward the dial indicator before then move again and set it to zero. Backlash is the total play that is evident during a directional change in movement. I think we are saying the same thing. I will come back to this one more time as I am in the process of changing out the ball nut on my x-axis. I like to measure its backlash to then be able to enter a value in the controller for compensation.
Einfach cool!
Danke !