Me too! Excellent video.

I was going to ask about the counterclockwise rotation thing, as it crops up everywhere. The mathematical explanation makes perfect sense. Thanks.

Hello Huib, that simple trick does work correctly on my DRO.

Make one! Make a project of it, use some 1/2" silver steel , cut a left hand 1/2" BSW thread on it, turn a taper on the end, then mill three slots of the centre line to give the cutting edges roughly on centre. Then harden. Then temper back to darkish straw and Bob's your mothers brother! ( I've made similar LH Acme taps for finishing new nuts for compound, cross slide and lead screw nuts on my lathe)

​@samrodian919 thanks for your help but I don't have the Equipment to make one .

You're not likely to find any manufacture interested in adding speed calculations to their DRO's. There are numerous obstacles, but the biggest is that it requires accurate timing, with interrupts, that would cause havoc with the cheap processors used in DRO's. There is a work-around though. Some DRO's provide a data output connection that can pass information to another device, which in turn could provide travel rate info. I did some research on this subject for a different purpose. I wanted to use a DRO's position information to control stepper motors for setting end points of movement. Unfortunately, the slow processing rate of DRO's can cause a significant delay in transmitting location data. It's been awhile since I've played around with this issue, but one option I've considered is to intercept the signals directly off the linear scales and feed them to a Raspberry Pi.

@@EDesigns_FL Thanks. I find that quite surprising since table movement is very slow compared to computers. Also, why should interrupts be needed? Measure X position, note real time clock value. Next time you have a spare moment repeat. Calculate speed., display.

@@samuelfielderBecause DRO's primary function is just counting pulses and then calculating positions based upon the counts, they have no need for a real time clock. Also, RTC's have a resolution of one second, which is a ridiculously long timing cycle for this type of application. Timing in these situation is typically done by running a loop of a known duration and counting the cycles to determine how long it took for an event to occur. Interrupts are used to avoid losing track of pulse counts for the linear scales while running a timing loop. When I write code to do something like this, if an RTC is available, I include a timing loop that runs upon startup to evaluate how many cycles a baseline loop will run in a given time. This data is used to set a timing variable for later calculations, and allows my code to run on any capable microprocessor irrespective of its speed. If an RTC is not available, then the code will be microprocessor specific.

@@EDesigns_FL An arduino without an RTC can time to milliseconds.

@@samuelfielder I don't know what your point is. There are numerous methods of timing events. You had mentioned using an RTC and apparently didn't appreciate the limitations. Some Arduinos do have RTC's. They are embedded in the WiFi board. I gave you a method that I have used for precision timing and it's the best that I have used for pushing the limits of mediocre processors.