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rising edge A as count and B as direction has been used for decades, but unless you guarantee to _always_ move more than half a cycle when changing direction it will count wrong

let say you are where A and B is low, move a little forward and A goes high,
now move back and forth so A goes low/high/low/high/low/high/low not moving far enough to make B change

if you only...

yes it is polling, don't think I ever suggested interrupts, you could put it in a pin change interrupt but you'll need to trigger on both pins and both edges, not all MCUs can do that

easier to...

haven't tested it but added below, must be called at least a couple of times faster than the fastest changes on the inputs


volatile int position = 0;

void quadrature_decode()
{
static...

the way described in that article is a bad way of doing it, it gives you alternating short and long steps, will count wrong on glitches and/or if the encoder is going back and forth over and edge
...

yeh something like a cannibalized roller skate or four big ball bearings and
a few lengths of bike chain

the video shows how tensioning is done by pushing the wheels against the pipe

for smaller pipe just use a shorter chain, for bevel cuts angle the cutter illustrated here;

How to cut steel pipe with an oxy-fuel pipe cutting machine. - YouTube

Ideally they should be spaced by 1/4 cycle.

but as long as they spaced by less than 1/4 cycle, (or a whole number of cycles + less than 1/4) it will work

it is maybe 10 line of C to do a proper...

I see what you mean, you want to rotate the pipe. What I had in mind was to have the pipe stationary and just have the cutter "roll" around it

a lot less hassle moving the cutter around than a...

a quadrature encoder could possibly control a stepper directly, the coils of a stepper is also driven in quadrature

you'll need a driven that phase input instead of step/dir input

yeh must be the etching, anodizing converts the surface to oxide that takes up more space the the aluminium it consumed so holes should get smaller

the ones I've seen the wheels aren't driven, instead a chain that goes around
the pipe also go on a driven sprocket so it both holds the cutter on the pipe and drives it, so the wheels could just be...

I think you would always get a problem at that spot,
Maybe if you do the joint at and angle and grid it after it is assembled or use three wheels on each side ?

yes they are for mounting on a circuit board

but that requires that you use a constant current driver, if you have a "dumb"
driver you'll need resistor to limit the current and they will get HOT

something like linistepper will also get HOT...

how much power, for how long and what is the max temperature you can live with?

wheels for roller skates and such sound like a perfect fit

looks a bit like AMP (TE Connectivity: Every Connection Counts - TE) "metrimate"

think I remember someone having a problem that sounds similar, turned out to be the shaft were no longer fixed to the rotor.

so the rotor sorta rotated but the shaft didn't follow

sparkfun have one: Stepper Motor - 29 oz.in (200 steps/rev, Threaded Shaft) - SparkFun Electronics
but it is rather small, the thread is some strange dual start 2mm/turn
and its a bit sloppy
...

if you can flatten it, it should be simple enough just run the rotary axis with the signals/driver for one of axis on a 2D machine.

just need to calibrate rotation angle with circumference

Amazon.com: Coin Op Oversized Pool Table Billiard Cue Ball 2 3/8 ": Sports & Outdoors

only 2 3/8 ", but at $6.61 ...

The second needs dual drive, on for each side of the gantry, the first can probably do with one central drive under the table

and as far as I can tell, how the cutting forces will work on the...

ethanol work great too, but spraying a flammable liquid all over the place isn't so smart, maybe it would still work if you mix in with enough water that cannot burn

somethin like this? Plasti Dip Protective Coating Products | Plasti Dip Protective Coating Products | Rubber Dip Coating

my first thought was to setup the rotating stepper as say the Y axis, and the side to side as X, then you just need to "draw" a zigzag line

set it up so the length of one zig is one turn of the...

a standard microswitch is less than a 1$, hardly expensive for an easy to mount very reliable switch

don't really think the difference is that big, in the brushed dc motor the
brushes and the commutator sequence the current through the coils
In the brushless a feed back system tells a controller...

or use countersunk screws, contact area isn't ideal but it'll align itself.
or use a small piece of 8mm od 6mm id tubing it is a standard size

get a vice with those 90degree notches in the jaws used to clamp round bar, or make two blocks with notches, so that you can clamp it diagonally ?