I use a standard sized SO3 with a Z plus screw driven z axis. I purchased an hdz axis and I am awaiting a 2.2kw spindle before installing the hdz z axis upgrade. My question concerns belt tension.
Is the upgraded z axis and spindle likely to require any changes in belt tension?
Each belt now requires only about 20 seconds to tension. I use a guitar tuner which senses vibration and I tune each belt to 135hz. They stay tuned for around 9 months so it appears that I have found the sweet spot for the 9mm Gates GT2 belts.
Your comments or thoughts about what impact the z axis and spindle change may have on the belt tension requirements would be much appreciated.
It never occurred to me that the extra weight of a spindle over the weight of a router would need my X or Y belts to be tighter. In other words, I didn’t change my belt tension when I upgraded to the spindle (S3XL) and I have not encountered any problems from my ignorance (in this subject).
Thank you for your response. My thinking was that the load on the stepper motors may be increased by the additional weight of the HDZ and spindle as the Z axis traverses the X rail. I was considering whether some additional torque may be required, as a compensatory measure for the increased weight that has to be moved. I don’t know if the steppers can be adjusted to provide more torque than they do from stock. As it is, I am really happy with my current arrangement but I want to upgrade to the ER 20 collet system and a quiet 2.2kw spindle, which will also be better for my longer work projects.
I do not know enough about the forces involved in maintaining good belt life and tension and what could possibly be done to mitigate additional excessive forces. I would hate to upgrade my machine and then find that I was chewing through GT2 belts much quicker than I do at the moment. The belts I have on my machine have been in use since October 2020 and show no obvious signs of having reached the end of a useful working life.
So, based on the measurements, the developed model and how I understand the machine to be working, no, you should not change the belt tension based on the weight of a moving axis.
The detail behind that is that the target belt tensions given in that post are based on the stepper motor limit torque (which is only achieved when stationary anyway, lower whilst moving) and any belt tension above this is creating unnecessary wear and stresses on belts and motors for no benefit in machine behaviour, increasing belt tension does not reduce backlash or increase precision, if there is a correlation, it is that things get worse when you exceed the design tensions.
As explained in the post, setting the belt tensions repeatably, as you are doing, and evenly between the Y axes is key to going and doing the calibration Will links to.
If you’ve not done so already, I found that switching to the kevlar cored GT2 belts assisted on my machine, at the cost of reduced belt lifetime.
The only change I’d make on the machine for a heavier spindle would be to reduce the accelleration settings in GRBL on the controller, however, I am running higher than stock max speed and accelerations on my SO3 XXL with the kevlar belts, HDZ and 2.2kW water cooled spindle so I don’t think you should bother…
Hi Liam. 10/10 for a perfect answer. Thank you very much. I will look at the change in belt construction. My GT2 belts are currently long lived and I have another new set which are still to be applied. The straight belt path has been an absolute revelation in terms of efficient tuning.
I see… thank you for this answer. Further on, you will see that @LiamN managed to give me more than enough information related to my enquiry. I may yet change my belts for kevlar belts. I will await the arrival of the 2.2kw ER20 spindle and VFD, and then I will install the HDZ and see what results I get with doing nothing further. My current belt tuning method gives predictable, reproducible results.
I will look at the change in belt construction. My GT2 belts are currently long lived and I have another new set which are still to be applied. The straight belt path has been an absolute revelation in terms of efficient tuning.