EMCO Compact 5 cnc Turret with dc motor and no feedback

Hi guys

does someone done a retrofit of the compact 5 cnc with turret with dc motor and NO feedback?

my way would be:

add a pyvcp menu to make move from tool position to tool position.

if i reach tool 1 i set with a button that its now tool1.

every move from tool to tool would lock first back and then drive forward to next position... 

turret can rotate forward free. Backward would lock it.
after locking backward reducing power is needed.

i have here a l298n modul and a mesa 7i92 with bitfile adjusted to have pwm and 2 gpios for setting direction.

i cant find a custom library for it. But is this the correct way to do it or i am complete lost? Its not the issue to set tool 1 manual over buttons.

Forward u would use pwm 100%
Backward pwm 60%
and holding against the pawl about pwm 30%

any ideas or help?

thanks

I got it work with a own component to make 1 move from position to position forwaes with lock backward and reduce pwm.

But the turret can only travel to next position in forward.

If i am on tool 5 and i want tool 1.. i need 2 times the move.
Is it possible to do this in the component with a abs function?

what i mean... i must handle the rollover=

presenttoolslots 6
currenttool is 6
calledtool is 1
Turretmoves = calledtool - currenttool = -5
Commandedmoves= presenttoolslots - (abs) turretmoves

next step is the to count every move.
moved = i++
if moved == commandedmoves
toolchange done

Sounds ok?!

I do the coordination of the forward and backward stuff with 2 time delays. On the end i set the pwm value lower to lock agoinst the pawl with lower current to not blow the dc motor.




Thanks

No because i have no feedback! Its only a dc motor and a disc that rotats in one direction and if you drive backward it looks against a pawl.

Here the mechanism

 


The dc motor drives a planetary gear.. the gear drives a wormgear.. the wormgear rotate the disc where the tools are mounted.


do you have a better solution without any feedback?
its not a issue to drive it to tool one and set it as tool 1.

i had years before mounted a stepper and done it with O Codes.. but the dc motor which was original used is bettee because it hold against the pawl. With stepper there is small small movement on the tool because its not holded against the pawl like the dc motor it does.

 

I start with a pyvcp panel...
Drive fwd 1 station button calls in section in my comp
Set tool 1 button calls m61q1

Then i add buttons tool1 tool2.... tool6 to call m6 t1....t6

If i hit drive fwd 1 station it rotates exact 1 station fwd. goes then backward and reduce pwm to get it locked against the pawl.

Now i check temperature ever 15 minutes of driver and dc motor.

Next step is calculating the distance from actual tool position to taeget tool position.. like from tool 1 to tool 6... or from tool 6 to tool 3... handling the rollover would be interesting... we will see in the next days.

If this done is the last step the movement... with the calculated distance on position to go forward i can multiplie with the forwardtime from position to position.. the locking part is not so sensitive.

So we will see... toolchanger without feedback... very oldschool... complete openloop.

Sam was working on this a few years ago.
Look at this.


It might help.

I got it working.

No feedback needed.
3 pins are used..

Forward
Backward
Pwm pulse

L298n cheap modul.

I clean up the component and then i make a small video und can share the code.

I use a 8 position toolchsnger from my emco 220 where i unmount the lightbarrier pcb.

How it works:

Start linuxcnc..
Then 1 time make movement over a button of the toolchanger.
Then look which tool is in position.
Then set toolnumber over buttons.

After this all is done over timing.
No motor noise!
No overheating!
No issues!

Rollover is handled.
The biggest problem was to find the correct timings and speeds.

The reason for the issue is that the dc motor has a planetary gear and the wormgear has small play.

You can setup:
How many toolslots you have
Time from slot to slot
Backward time
Backward locking time

Pwm for forward
Pwm for backward
Pwm for locking against the pawl

Advantage:
If you hit emergency off the toolchanger stops and resets

You can add reference signal to tool1
You can drive toolchanger from slot 2 slot over buttons.

You have pins where you csn see if you have rollover and the slots it must travel.

Its complete openloop and can setup over a hal or halpkns