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rapid speed / creep speed movements
Posted: Wed Jun 08, 2016 11:05 am
by dampfboot
At my milling machine I am used to program most movements with two different speeds. A rapid motion will bring the tool head NEAR the desired location with full speed. The rest of the travel till the work piece surface will be done in creep speed. The length of the creep speed path will be defined by a safety distance. This method can speed up the process a lot.
I would like to see such a strategy in the Liteplacer software also. Especially with all the parts in their already opened compartments would make quite a mess when hit by the needle under full speed. I know that this is not easy to implement but maybe in the future we will get this feature in the great Liteplacer software. For beginners you could have a simple mode in the software which moves everything in the same speed...
PS:
I do not want to hit the parts with the speed shown in the second part of my little video
https://youtu.be/tGaQKxmDwhw
Re: rapid speed / creep speed movements
Posted: Wed Jun 08, 2016 12:32 pm
by mawa
The TinyG motion control decelerates the stepper down to zero according to the set final position of a move.
There are some impressive videos showing TinyG superior acceleration-decelerations algorithm.
So the speed during movement is only a matter of how fast you can step without any step loss.
When the final Z position is exactly before the nozzle touching the component there will be no force put on the component.
To find this Z position the liteplacer software probes the height using the z-limit switch plus the backoff value needed to compensate the switching distance.
Probing is used the first time when a component is picked up from the tape and when it is put down on the PCB. The tapes Z Values have to be cleared to achieve this behavior.
So if you run into the component either your z probe was inaccurate or your backoff value is too small.
Re: rapid speed / creep speed movements
Posted: Wed Jun 08, 2016 12:44 pm
by dampfboot
Thank you Manfred for the explanation - have to play with the figures given by you...
Re: rapid speed / creep speed movements
Posted: Wed Jun 08, 2016 1:47 pm
by JuKu
Thank you mawa, your wording is better than I would have written. One more detail: The probing speed uses Z homing speed parameters.
Re: rapid speed / creep speed movements
Posted: Wed Jun 08, 2016 2:15 pm
by dampfboot
Thanks again!
I am just at the beginning of using the Liteplacer software and there are so many things to learn
- good to have such a friendly supporting forum!
Re: rapid speed / creep speed movements
Posted: Fri Aug 19, 2016 4:14 pm
by JuKu
For the nozzle change setup, I needed to implement this. I ended up using full speed for the change, as I see no ill effects for that. Still for setup, it was very handy. It is assuring to set the machine to move very slowly and see, that it actually does everything right without crashing at high speed to the holder.
So, this is implemented. Is there any good use for it elsewhere?
Re: rapid speed / creep speed movements
Posted: Sat Oct 15, 2016 6:30 am
by EdwardsKathleen
speed during movement is only a matter of how fast you can step without any step loss.
When the final Z position is exactly before the nozzle touching the component there will be no force put on the component.
To find this Z position the liteplacer software probes the height using the z-limit switch plus the backoff value needed to compensate the switching distance.