How to estimate/measure the size of stepper I need
the background:
i have macro focusing rail system slr use take "stacked" macros, take picture, move camera tiny bit closer, take picture, move tiny bit more, take picture, etc.
there device called stopshot want, costs on $500 us, , have precision set of macro rails. plus, excuse build arduino, , use stepper motors well!
to results need dozens of images, , best if adjust rails using motor instead of turning knobs hand. there @ least 2 reasons:
1. it's best not touch camera rig, since tend cause small movements throw off alignment between images
2. rail system has fine control of focus, , tight adjustment knobs, there no markings or detents. can't measure or control amount turn knob between shots, aside putting paint mark on knob , mentally dividing full turn 1/4 turns, , each 1/4 turn 4, total of 16 rough steps.
i need turn knobs , precisely, small increments (64 steps per rotation good, maybe more.) in normal use system turn knob tiny fraction, wait few seconds vibration settle down , trigger camera, repeat. 3-5 seconds between adjustments right.
for moving rails 1 or other limit of travel, 1 or 2 rpms fine max speed. getting accurate rotation without missed steps more important fast rotation.
the control knobs stiff, keep rig slipping. motion smooth, there quite bit of resistance. takes firm turn rotation. feels viscus fluid damping.
how can measure/estimate amount of torque need, , size of stepper should get? have torque wrench working on camera measures torque down 2 nm, no lower. don't have sense estimating torque, , don't have tools measure torque less 2 nm. i've read, heavy duty steppers seem have torque in range of single-digit newton/cm.
since speed needs low away geared stepper. give me more steps/rotation plus higher torque, don't know how figure out need.
suggestions?
i have macro focusing rail system slr use take "stacked" macros, take picture, move camera tiny bit closer, take picture, move tiny bit more, take picture, etc.
there device called stopshot want, costs on $500 us, , have precision set of macro rails. plus, excuse build arduino, , use stepper motors well!
to results need dozens of images, , best if adjust rails using motor instead of turning knobs hand. there @ least 2 reasons:
1. it's best not touch camera rig, since tend cause small movements throw off alignment between images
2. rail system has fine control of focus, , tight adjustment knobs, there no markings or detents. can't measure or control amount turn knob between shots, aside putting paint mark on knob , mentally dividing full turn 1/4 turns, , each 1/4 turn 4, total of 16 rough steps.
i need turn knobs , precisely, small increments (64 steps per rotation good, maybe more.) in normal use system turn knob tiny fraction, wait few seconds vibration settle down , trigger camera, repeat. 3-5 seconds between adjustments right.
for moving rails 1 or other limit of travel, 1 or 2 rpms fine max speed. getting accurate rotation without missed steps more important fast rotation.
the control knobs stiff, keep rig slipping. motion smooth, there quite bit of resistance. takes firm turn rotation. feels viscus fluid damping.
how can measure/estimate amount of torque need, , size of stepper should get? have torque wrench working on camera measures torque down 2 nm, no lower. don't have sense estimating torque, , don't have tools measure torque less 2 nm. i've read, heavy duty steppers seem have torque in range of single-digit newton/cm.
since speed needs low away geared stepper. give me more steps/rotation plus higher torque, don't know how figure out need.
suggestions?
i think first decision drive mechanism - leadscrew or toothed-belt.
this affects steps/revolution, torque requirements.
you need estimate of load mass , friction in the
guide rails - instance camera moving on level or
does gravity have overcome too?
what resolution need camera movement? - affects the
belt v. leadscrew decision. most hybrid steppers 200 steps / revolution
these days, that's assumption can make. remember
microstepping gives little more resolution, not dramatically more
(microstepping reducing noise , resonance).
[ , should add once have drive system can estimate or measure
the friction (which may dominant). nema17 size enough
as go upto 0.4nm pull-out torque. smaller steppers nema11 are
actually harder find anyway. ]
this affects steps/revolution, torque requirements.
you need estimate of load mass , friction in the
guide rails - instance camera moving on level or
does gravity have overcome too?
what resolution need camera movement? - affects the
belt v. leadscrew decision. most hybrid steppers 200 steps / revolution
these days, that's assumption can make. remember
microstepping gives little more resolution, not dramatically more
(microstepping reducing noise , resonance).
[ , should add once have drive system can estimate or measure
the friction (which may dominant). nema17 size enough
as go upto 0.4nm pull-out torque. smaller steppers nema11 are
actually harder find anyway. ]
Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > How to estimate/measure the size of stepper I need
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