[SOLVED] servo motor pulse time calculation doubt

i am moving a lathe x and z bed using servo motor. my servo motor drive accepts step and direction pulses

i need a formula to calculate my pulse time according to the feed rate

assume for 1mm bed movement i am giving 300 pulses to servo drive ( square pulses )

case1:


my feed rate is 1 mm per second (that is in 1 second it must cover 1 mm movement) so the pulse time will be 3.33 ms ( (1/300)*100)

case2:

my feed rate is 2 mm per second ( that is 1 second it must cover 2 mm movement) so the pulse time will be decrease to 1.665 ms

case3:

my feed rate is .5mm per second ( that is 1 second it must cover .5mm movement) so the pulse time will increase 6.66ms

and so on the value of feed rate will change according to the job

i need a formula to calculate the pulse time corresponding to my feed rate setting

kindly help


regards
kalyan

From the figures you give:

Pulse time = .00333 / feed rate

(Feed rate is in mm/sec.)

can you tell me how you got .00333 value

Hello!

can you tell me how you got .00333 value

Click to expand...

This is pure elementary school math.

300 pulses move your bed (or anything else) by 1 mm.

I suppose you agree that the feed rate will be proportional to the pulse rate, right?

If you want 1mm/s, then enter a square pulse at 300 Hz.
If you want 2mm/s then double the frequency of the pulses (therefore half the period).

Therefore, if you want a feed rate of F (mm/s), then you should enter a frequency of
300 * F.

I suppose you can finish the calculation.

Dora.

You observed that pulse time goes up, as feed rate goes down.

This means you can't use a simple multiplication factor. Instead you divide something into something.

I had a suspicion it had something to do with your 3.33 mSec being related to 1 unit (namely mm).
I moved values above and below each other. I rearranged them to the left or right of an equals sign.

I checked whether it resulted in the correct answers for case 1, 2, and 3.

Finally the correct equation emerged.

Hello!

You observed that pulse time goes up, as feed rate goes down.

Click to expand...

Yes, that's why I wrote that the feed RATE is proportional to the pulse RATE.

Dora.