I am new to CNC and I am learning as I go. I have finished the mechanical build of my Ox CNC and I have used 1500mm extrusions for the y axis and 1000mm extrusions for the x axis/gantry.
The bed however sits slightly off square. The side lengths are all the same but there is about a 4mm difference in the diagonals. So its more of a parallelogram. The difference is quite small but the gantry ends up siting slighting off square on only one end of the bed as well (when one side is at its limit the other is about 3mm off). Is the difference small enough to ignore? Should I continue to try adjust it until I get rid of the slight angle? (I have tried and found that this is the closest I could get it.)
Hi Thomas welcome to the OX group. I am also new to CNC and have just about finished my OX. It can be difficult to get the frame perfectly square as I am dealing with a similar issue but with less error. I have about less than 1<mm off set in my Yaxis that I am not sure I can fix. I need to double check my X Axis but I would think 3mm is way to much to accept, that’s about 0.118". I work with measurements allot at work and visually know what 0.118" looks like. To me this would not be acceptable. With that said what are you planning to use your CNC for? This could help determine how much error you are willing to accept. For precision parts you should be within 5-10 thousandth of an inch accuracy. That’s about 0.2 - 0.3mm. Also remember that of you are off in one place you are off in another this can add up to be a big difference in accuracy of your final cut.
Thanks for getting back to me so quickly and for the great advice. I really appreciate the support from the community. I had the feeling that I will need to spend the time to make it much more accurate. I have started designing a couple jigs which I can use to square up the OX and then I will be adding in a thick plywood base (which is easier to make precisely square) to secure it once as it is square.
I will be using the CNC machine mainly for woodworking and different wood and metal inlays along with some experimenting to learn what I can do with it and how far I can push the machine. I am also a multirotor/FPV enthusiast and I hope to make my own frames with different mediums.
Cool! Sounds like you need a reasonable amount of accuracy than. One thought I had was that if you use a surfacing bit and surface your spoiler board it should essentially create any slope in the X axis to match the spoiler board. So your part sitting flush on the spoiler board should be at an even 90 degree angle to the X axis. I wouldn’t say it’s ideal but it could reduce or eliminate the problem.
First post so hello yall, I’m a FOSS/OSHW advocate, brand newbian CNC/Making enthousiast from south of France planning to build an OX before the end of the year and learning from all the knowledge and experiences you, pionners, share with the rest of the world… lifetime gratitude for that !
About the squaring issue, couldn’t it be resolved with two cables along the diagonals with micro-metric adjustment tension screws ?
There are really 2 things that you’re trying to square here. There is the frame. The 2 Y rails should be parallel and square to the front, altough this part isn’t really essential. Then you want your X axis to be square to the Y axis. If your X axis is not square, I’d release the belt tension (on the 2 Y belts) and see if it has a natural tendency to sit square or sit at a slight angle. I’d try to fix this first. If the stepper on one side skips and the stepper on the other side doesn’t then that can cause your X to be out of square with your Y, but when the system is powered off it will tend to try and go back to it’s “natural” position when there was no tension on the belts.
If you find that the side plates are not square with the X axis, then this probably means that the beams weren’t quite square when they were cut. You may be able to shim them using something like aluminum foil
Awesome! Thanks for the advice! Once as I get some time I will start looking into approaching the issue with this information and decide on the best plan of action.
I used L brackets on side of gantry plates and screwed them into sides of x-axis, replacing those single corner brackets, they were too flimsy for my liking. Only when those L brackets were secured did I screw in the screws between plates and!-axis extrusion.
That done fixed my x-axis square issues to <1mm