Help please. Dip switches and mach 3 settings

[Radu_Andrei]

Ok. I tried it like this.
From left to right in the photos and video, drivers set at 800/1600/2000 with motor turning acc 50 and velocity 400.
There is a difference, as the 800 one runs smooth without vibration when touched. The noise difference exists even between steppers with exact same settings so not sure if it matters.
https://www.youtube.com/watch?v=dsHN_Botomk

Also, changing the pigtail connection with a terminal one, seemed to improve a lot, but still sometimes it does like in this video https://www.youtube.com/watch?v=4nHuNHK4fLA

What still does not seem ok, is that when I run DriverTest in Mach3 folder, I get the first time ..Pulsing to fast and then pulsing to slow.. messages and then runing it again, I get System Excellent (apx 25000 pulses per second, 25 khz), straight line.

Everything is taken apart like in the photos, so design wise, I got the fact that the vfd has to be somewhere outside the control box, or in it.s own box, but what about the pc? Any issues with the motherboard being close to the Bob?
As I shielded the boxes with sheet metal, it seemed to get warm inside, which did not before ,with just the wood ones. So, the new box will be a cleaner version of what I did, and I have two 12v fans. How would to mount this, in order to avoid dust collection, as much as possible and overheating? Blow in or our, from above, from beneath? I.m asking about the control box.

How do you suggest , I should test the steppers to make sure all iss good, and proceed with building the metal box?

[Radu_Andrei]

Also I found this wiring diagram online, and it.s quite different from what I.ve done.
I go to BoB from Pull- and Dir-and this one goes from +.
Enbl+ is daisy chained and wired to the Vdd, while mine is bridged to Pull+ and Dir+.

Do this small differences matter in any way?

[john swift]

going by your photo in post 35

without circuit details of your breakout board
I expect the opto isolated BOB NPN outputs will be connected
so they can output sinks more current to GND
than it can source current from the +5V supply via a pullup resistor

If I am correct
I would connect the BOB to the stepper drivers like this :-



the + step & +direction going to the +5V supply and
- step & - direction being connected to the BOB outputs



John

[Radu_Andrei]

This is the one. Db25 1205. https://www.ebay.com/itm/CNC-6-Axis-...sid=m570.l1313
I don.t know any more details that it says in the lower side of this webpage.

The multimeter reads 5v at the VDD terminal, without bridging it.
I did it like in the photo you.ve sent, but bridged ENBL+ as well.

Thanks for your reply. :)

[john swift]

going by the photo linked to in post 38

it looks like the BOB is as I expected with pull up resistors on the outputs



unless you connect the - enable to a BOB output
having the + enable connected to +5V will have no effect

what could be a problem is having the BOB's output optoisolator being connected to another optoisolator inside the stepper driver

having the step signal passing through two optoisolators could distort the pulses too much at high step rates

John

PS
in the photo of the BOB you can see two links that connect the +5V in to Vdd and connects the two GND's together so you don't need the external wire link as in post 37

PPS
a while ago I produced this circuit diagram from photos taken from the net



what I need to confirm is the connection of the 10K resistor connected to the 74HC14 input
it was not clear from the photos if the resistor was a pull up to +5v or pull down to GND

[Radu_Andrei]

Hi John,
ˇˇwhat could be a problem is having the BOB's output optoisolator being connected to another optoisolator inside the stepper driver/having the step signal passing through two optoisolators could distort the pulses too much at high step ratesˇˇ - does this mean I should remove the bridge from enbl+?
ˇˇwhat I need to confirm is the connection of the 10K resistor connected to the 74HC14 input/it was not clear from the photos if the resistor was a pull up to +5v or pull down to GNDˇˇ - how exactly can I help in confirming this?

P.S. although I have some general knowledge about diodes, capacitors and resistors, I.m struggling to wrap my head around schematics, so I.m sorry if my replies are quite banal. I very much welcome reading material to avoid pushing the limits of anyone.s patience. :)

[Clive S]

. I very much welcome reading material to avoid pushing the limits of anyone.s patience. :)

Don't worry about this. I believe John is very experienced in electronics. Just go through it with one small step at a time.

Also have you disabled all the crap like screen savers and stuff in the bios that is not needed on the pc.

[john swift]

combining the circuit of one of the BOB outputs with the circuit f the stepper driver inputs :-


when the printer port or motion controller goes high
the output of one of the inverters in the 74HC14 goes low and
about 10.6mA flows through the opto isolators LED
the light turns on the NPN photo transistor that in turn pulls the
stepper driver negative input down to ground
(- step in the circuit example)

about 16mA flows through the stepper drivers input LED

the problem is when the BOB input goes LOW
the BOBs opto isolator LED is turned off but the NPN transistor takes a while to turn off
the square edge of the step pulse gets rounded off
delaying when the stepper driver LED is turned off

while I expect a faster opto-isolator is used inside of the stepper driver
the NPN photo transistor inside the drivers opto-isolator will further degrade the step pulse


John

PS
propagation delay through a high speed opto-isolator



not only is the signal delayed but the edges are rounded - see page 4


PPS

in another thread to use surplus Tormach stepper drivers

https://www.cnczone.com/forums/torma...ml#post2107952
from the above post




you can see the Tormach / Leadshine stepper driver uses a HCPL 2531 dual high speed opto isolator for the step & direction inputs

a slower FL817 opto-isolator being used for the enable input
the "817" being the opto-isolator I expect your BOB to have