acceleration is a bit pointless without direction (why do you NEED any specific acceleration number)....
first define what you want to cut?
material (ms/as/aluminium)
thickness (whatever)
then define what do you want to cut it with?
Amperage
what consumables? (fine-cut, 30a in a 45a machine) whatever
this should give you a feedrate number, and if you have a range of materials you cut decide what your preferred is (define a bit more than "everything" in the cut charts..... I mean are you really going to cut 0.8mm AND 12mm (1/2")?.... seriously!
let's say like me you are going to do mild steel, 2mm, 4mm and 6mm.... but obviously anything that is within your machines capacity remains an option
now think about the accuracy you expect.... inside corners, arcs and maybe outside corners are your consideration here.... if you cannot loop your outside corners.....
your limiting factor will always be your kerf as you ain't going to get tighter than that but also the trailing arc or cut (15 degrees I think is the norm at the recommended feedrate (it may be 5-7.... I forget....)
the trailing arc you can improve on by slowing down as it will catch up..... half the feedrate.... the trailing arc angle will be half that at the recommended feedrate ..... also on thin material it won't be that evident ... because of the kerf to thickness relationship.
there is also the good side of the cut (outside cut.... clockwise.... inside cut .... anticlockwise cut direction... good side on the left of the cut).... this still has a bevel 3-5 degrees at the recommended feedrate from memory..... worthwhile remembering regarding precision cut parts....
all these considerations regardless how trivial they are to you .... may actually form part of what you consider to be your acceptable precision.... and your acceptable level of acceleration.
the minimum recommended hole diameter tends to be 2xthickness (maybe 3x) for plasma .... anything less than this.... dimple (not pierce!!!) and drill.
if you need to reamer a hole.... dimple + drill (yes I have mounted bearings in an interference fit reamered hole as a hobby user adapter plates for a CNC mill conversion) as the edge of the cut will be hard and not help your drill bits and expensive precision reamers.
so back sort of on topic.... say you decide that the smallest hole will be 6mm dia (3x2mm mild steel plate).... allowing for a 1mm kerf this is actually a 5mm dia gcode path.... kerf may get a bit wider in practice .... say 1.5mm given we are going to slow down to the recommended 60% of linear feedrate so we are now at 4.5mm dia.
hell, for argument's sake say the smallest arc I ever want to cut is 2mm radius at 60% linear federate in mild steel with a 2mm thickness with a 45A plasma cutter with 45A consumables so the federate recommended from the book is 5560mm/min and ~7000mm/sec (hypertherm 45 non xp using duramax torch or original machine torch)
say 7000mm/min worst case..... 60% allowable federate for arcs and corners says it can drop to 4200mm/Min (70mm/sec). .... the minimum arc is 2mm or 2.5 or 3mm.....
ACC = vel^2 / radius.... (physics)
so the minimum acceleration I would need is 2450mm/s/s [0.25G] (for a 2mm arc radius), or 1960mm/s/s [0.2G]for a 2.5mm arc, or 1633mm/s/s [0.17G] for a 3mm arc
anything more than these acceleration figures don't actually help the cut really....
another interesting consideration is to cut a 4mm circle in gcode at a feedrate of 60% of the recommended linear feedrate how much lead-in and over-cut do I really need if I am using a torch with instant off in sync with motion M63 + delayed (overcut) m5...
at 4200mm/min or 70mm/s you will need a minimum acceleration distance of 1mm at 2.5G......
seems like in my case 2.5G would be a nice comfortable number to have as a target .... anything over this is not beneficial.... and may actually be detrimental..... yup detrimental because I would be placing undue stress on my components and system to achieve no benefit....
why you may wonder (or not if you cannot be bothered).....
YMMV.....
say I am running steppers and they have a step resolution of 0.05mm/step .... other than being course what does this mean????
well for acceleration it means that in 1 step it has to accelerate from rest to 0.25G... and at the end of the acceleration profile it has to decelerate from 0.25G to zero acceleration again in 1 step
time is the important criteria here.... how long is the first step.... at 2.5G this would be 0.006388766 seconds.... the jolt / jerk is therefore 383,485.6581mm/s/s/s
at 0.3G this would be 504,876.7751mm/s/s/s
which is ~30% more stress I would be placing on my components than needed
hopefully this is useful to someone as at least a consideration..... I'd go so far as to say that I would like the acceleration to be adjustable..... I clearly don't need 2.5G acceleration if I am cutting 4mm or 6mm or greater materials... so why not make the acceleration adjustable to a degree....
