New Machine Build- Early 80s CHNC 4 lathe build

[Kevin77]

Hello all,

As you can see from the title, I'm starting a machine build. This will be my first. I'm well versed in computers, electronics, and CNC machinery, but have no experience yet with Mach.

The machine is in good shape mechanically, but the General Numeric 6T control is on its way out, and the turret quit indexing properly.

So, getting the X and Z axes moving doesn't look like a big challenge. However, I want to ditch the air turret setup and replace it with a servo or stepper system for reliability. I assume I would want to do this via an external PLC? I know some people have done this- can anyone point me to specific threads that cover this topic? I don't know much about PLCs either.

Second, this machine has an air-driven vertical slide (Or it might be air over hydraulic- do these machines use hydraulics for anything else?). Does anyone have experience with these? It's setup for cutting-off now, but I wonder if it could also be used for forming and other ops.

Does anyone have a source for manuals for this machine?

Any help is appreciated, as well as suggesting favorite hardware options. I really like the Granite Devices drives and Pport interface (though obviously I haven't had any experience with them.)

I'm not trying to do this on the cheap. This needs to be a reliable machine when done.

Thanks,
Kevin

[Karl_T]

I rebuilt one of these over to a Camsoft control. There was another fella here on the zone that did a build thread going to a Mach control. IMHO, Mach isn't a great choice for a brush servo machine needing PLC function. I'd take a look at EMC if you don't want to spend the big bucks for a Camsoft control. OTOH, I would not suggest Camsoft to a first time refitter either.

Machine manuals.net has the manual for your machine. The slide is air driven but I don't use it. The air turret can be a weak point. If you design a way to do it with a servo or stepper I'd sure be interested. I've had it apart more than once, not sure how this could be done.

[najnielkp]

i have done a chnc 4. gutted the turret air motor and used the shaft coupled to a size 23 stepper driven by a gecko 201. the cover over the x axis motor needed to be extended.installed a solenoid air valve to raise and lower the turret.it works very well.used gecko 320 drives for the x and z axis motors.

installed us digital e5d 250 line encoders on the x and z axis.removed the dc kolmorgan spindle motor and used a 10hp 600v 3 phase with ab 1336 impact vfd drive. made an adapter plate for the spindle and mounted a 3 jaw chuck.i removed the hydraulic slide . part off from the turret. any questions just ask.

[Kevin77]

[QUOTE=Karl_T;916069] IMHO, Mach isn't a great choice for a brush servo machine needing PLC function.

What's your reasoning for that?

And has anyone else controlled a turret using Mach? How does Mach output tool change info?

Kevin

[Kevin77]

Originally Posted by najnielkp i have done a chnc 4. gutted the turret air motor and used the shaft coupled to a size 23 stepper driven by a gecko 201. the cover over the x axis motor needed to be extended.installed a solenoid air valve to raise and lower the turret.it works very well.used gecko 320 drives for the x and z axis motors.

How did you handle the toolchange logic?

Thanks,
Kevin

[Karl_T]

[quote=Kevin77;916231]

Originally Posted by Karl_T IMHO, Mach isn't a great choice for a brush servo machine needing PLC function. What's your reasoning for that? And has anyone else controlled a turret using Mach? How does Mach output tool change info? Kevin

I'm not going to dis Mach. But EMC handles 10 volt analog to servos and takes feedback from encoders. Mach outputs steps, no feedback. It can be made to work with a step servo driver.

I've only watched threads on PLC function with these two controls. The guy that I mentioned using Mach on his CHNC had an awful time with PLC and it was his fourth machine. You should search out this build thread.

Again, I've only watched threads. EMC is made to easily add additional IO. From what I've read, the logic can be done right inside EMC, but check it out. A fella named Jon Elson sells and supports the stuff you'd need for this route.

For myself, I'm plumb spoilt. Camsoft is a nuclear weopon compared to either control.

Just my 2 cents. Take some time to check it out.

Karl

[Karl_T]

Originally Posted by najnielkp i have done a chnc 4. gutted the turret air motor and used the shaft coupled to a size 23 stepper driven by a gecko 201. the cover over the x axis motor needed to be extended.installed a solenoid air valve to raise and lower the turret.it works very well.used gecko 320 drives for the x and z axis motors....

Man, I'd like to see pictures of this.

The air turret never gives trouble for me. But the stop pawl does. Were you able to eliminate this?

Karl

[najnielkp]

i a using mach 3. the solenoid on/off and the rotation is controlled by a macro.
i will post the macro and pics later today.
the toolchanger is not as fast as the air motor drive , but does not require the encoders, or the stop pawl.i found that you do need to rotate in 1 direction only
as there is some backlash in the worm drive. the only time it has not indexed properly was when the spinning tool hit an obstruction.

[najnielkp]

here are some pics of the x axis with the cover removed. the stepper motor is a size 23 400 oz-in double stack. the airmotor was gutted and the shaft extended. i reused the airmotor body as it screws into the carriage and also locates the worm gear on the end to the turret gear. used a lovejoy coupling as i had to slide it all together after the stepper was mounted onto the endplate. encoders are easy to install using the existing resolver mounts. you can see the solenoid air valve and lines that raise and lower the turret. there are 2 1/8 npt ports under the access cover from the top. the solenoid valve is activated and deactivated from a 5v ttl relay board by mach.used a relay board from futurelec. the z limit switches are hall effect. the x axis limits are optical snap action. i found that you need to keep the voltages over 12volt dc work properly. used a opto input to 5 v ttl input board from futurelec also. index pulse is from a hamlin hall effect sensor . on the rear of the spindle housing , there is a cover that contains a belt driven shaft and encoder. i drilled a small hole into the timing pulley rim and epoxied a neodynium magnet.

here is the toolchange macro that worked for me.

Sub Main()

NumSlots=8
OldTurretPos=(GetOEMDRO(803))
OldToolSlot=Abs(GetOEMDRO(803)/45)
NextTool = GetSelectedTool()
NextToolSlot = (NextTool-1)*360/NumSlots


If OldToolSlot = NextToolSlot Then
SetCurrentTool(NextTool)
Exit Sub
End If

If NextTool>8 Or NextTool<1 Then
Message("Next Tool out of range")
Exit Sub
End If

MoveDis = (NextToolSlot-OldTurretPos)

If Abs(MoveDis) >180 Then
If MoveDis < 0 Then
MoveDis = 360 + MoveDis
Else
MoveDis = MoveDis - 360
End If
End If

ActivateSignal(output5) " raised the turret "
sleep (1000)


Code "G00 G91 A" & MoveDis
While IsMoving ()
Wend

DeActivateSignal(OUTPUT5) " turn off port for raise turret"
sleep (1000)
ActivateSignal(output6)" turn on port for retract turret"

While Ismoving()
Wend


DeActivateSignal(output6) " turn off port for retract turret"

sleep (1000)

SetCurrentTool(NextTool)
Code "G90"
End Sub

[Kevin77]

Thanks for the pics and code. Can you explain how Mach handles the stepper drive for the turret? Is it treated as an axis? Is Mach outputting step & dir. for the turret rotation?

Thats the only part I'm hung up on. Raising and lowering the turret seems like simple IO stuff. How precisely does the turret position itself? Is there any misalignment before the turret drops back onto its locating pins?

How does the turret encoder interface with Mach? Does Mach read 8 distinct turret positions, or does it just count from one to the next? I.E. "I was at #5, so I need to move CW 3 pulses to get to #8"

Sorry for all the questions, just never worked with this before and am trying to wrap my head around it all.

Thanks again,
Kevin

[phomann]

Hi Kevin,

You may want to consider using a ModIO as a controller for your toolchanger.
MC-01 ModIO Controller [MC-01] - US$98.00 : Homann Designs, The Preferred CNC Component supplier

The ModIO communicates with Mach3 via Modbus. It includes a number of Toolchanger modules in it, and I have added more as users need them.
The modIO has 8 open outputs and 8 inputs, enough for most toolchagers.

The Toolchanger module in the ModIO is controlled via the M6 toolchange macro that I provide.

Below is a video of a Hercus lathe that uses the ModIO.





Cheers,

Peter

[najnielkp]

the turret is setup as the a axis. so once you calculate the steps per 360 degrees of the turret , it will always index to the commanded rotation.