I have a 1515 running a blackbox. I am building drawers that are 22 x various widths. I have used the calibration wizard in openbuilds and on 22 inches I am gaining a quarter inch. The width is very critical as too wide will cause the full extension slides to bind. What could I or the machine be doing to cause this. Thanks in advance.
Then either your calibration is still off (redo, make sure to use longest possible move for the measurement you can enter your own move length in the wizard, make sure to measure perfectly) or something is mechanically loose (slipping shaft coupler due to loose setscrews, loose stop collar, etc?)
Thanks Peter. I ran the calibration wizard multiple times and I only got it close. Too short and then too long, then too short, back and forth. I clamped a steel ruler to the rail, backed the plate into the rule to make sure it was square, moved it the 100 mm and used digital calipers to measure between the plate and the ruler. I will try running a longer test. Everything is tight and the mistake is repeatable. I am thinking if it was something loose, I would be coming up short not long? Thank you for your suggestions. I will try them. Any other thoughts?
Just a thought regarding your machining op settings and diameter of the cutting tool. For example, when a shape is cut - I am using a profile cutting settings and the default setting is to cut to the inside of my shapes line - using a 1/4" diameter endmill - my final result is approximately 1/4" short on all dimensions. I must remember to set to cut to the outside of the shapes line. If these settings are not an option with your CAM program - try adjusting the size of the shape to account for the diameter of the cutting tool.
Thanks for the input. My cut is set to outside shape and my bit is very close to .125. The most I would be out is a couple of thousandths of an inch.
Indicating mechanical (go over everything again) Typically when calibrating (if done right) it just keeps getting better and better. too short too long over and over is either operator error when measuring or entering actual move (doubtful here) or, the machine has slippage somewhere. Go over all the setscrews, shaft couplers, stop collars, tension nuts, make sure leadnuts aren't sliding around against the plates because they weren't tightened to the plate correctly, etc It may be "slipping short" during calibration messing up the numbers - thus showing up as overshoot during jobs. Quick mental check for that is your steps per mm should be around 199-200. Calibration should take it between 197-202 at most - usually more a correction in decimals. 199.1 is our profile number (they are usually just a minute little under the theoretical number of 200 steps per mm)
Also, use the entire length of your axis as your measurement if possible. In other words, put a tape measure (or meter stick) down and measure out 40 inches and use that as your length. The longer your length, the more accurate your calibration. Here is a video of how I did mine. You can see I am off by 0.3 mm in 1000 mm in my Y axis. I would have never noticed that error in 100 or perhaps even 500mm. Ignore the painfully slow acceleration rates. I have the optimized now.
I truly do appreciate your suggestions Peter. I will check the mechanical fasteners. I am 100 % confident my process for measuring is accurate(said with gentle effect) but will do it again with a longer test. I am very fussy when it comes to things being correct(to a fault actually) so I am thinking of going to a machine shop and getting them to cut me a flat bar at exactly 1400 mm. I cannot think of any other way to measure with precision as most tape measures have a +/- margin of error. I am open to any suggestions.
Thanks for the video. That is what I have been doing, just on a much shorter length. I am going to try it on a longer run.
I ran the wizard again at 46 inches and I was out .25 inch. adjusted the steps and I am less than an 1/8 inch out. I have done lots of projects (signs, 2.5 carves, rocking horses) but accuracy has never been an issue until now.
don't forget to reset the blackbox after changing the steps/mm numbers. my process is to go back to 0, then hard reset, then run the calibration again. I found that weird things happen without the reset (-:
