[narrobb]

I designed couple of mods for my machine last week and sent out the circuit boards to be fabricated. Courier just dropped them off.

Power Drawbar mod: Two reasons for this one; first, I did not like how it operates by keeping the button pressed. I know there is a foot pedal and I am not sure if you can press for release then relax or go away then press again to engage. If it wasn’t for the 2nd reason, I would have probably investigated the foot pedal.

The mod allows pressing once to release, then pressing again to engage. With a neat feature that it goes back automatically up if nothing happened for 10 seconds (or 20, 30 sec options). This is just so if I got distracted with a phone call or took too long to put the other tool, then the controller pulls back the bar so not to keep tension on the bar. I can change the time for auto-return by using the top button on the pendant to cycle between the auto-return time options.

The 2nd reason is Safety; when I was installing the PDB, I really thought the two blue wires (105/106) that goes from the PDB to the main control board is for the machine to tell the PDB circuit that the spindle is running, so the PDB does not operate. I was mistaken, I discovered that the two blue wires are really for the PDB to tell the machine that it is going down! So if the spindle is running, then the machine stops it ( similar to opening the door)

As an engineer that been designing control systems for the past 20 years, this did not make sense! So the drawbar will be pushed down even if its rotating 1000’s of RPM! Well, I had to try it (Doh!!) I put the spindle at the lowest RPM, no tool inserted. Pushed the button, guess what?! Spindle started to stop (it winds down) drawbar got pushed down, locking the R8 adapter and while the bar still winding down, it unscrewed the R8 adapter, it got dropped on top of my surface and I got a small ‘visible’ dent to remind me of that.

I realize that probably no one would want to push the button while the machine is cutting but its not really hard for this to be done correctly in the first place. If the spindle is running, PDB should not be allowed to operate. In design world; we can’t assume the operator is professional enough to understand and not do certain things; design should be for the village idiot (no pun intended) and goes up from there. Only in the issues that can’t be resolved in design, then we rely on education/training and increase awareness.

This is a microcontroller board with straight forward installation, the RJ11 from the pendant goes into the right port, a small straight RJ11 goes to the left port and that's all, the microcontroller now took over the pendant and tells the PDB when to release or pull up.

I optimized the firmware so the whole board only consumes 0.5 milliamps. And added full optical isolation circuit to accept external control from another board which tells it if the spindle is running or not. The isolation keeps the entire PDB isolated from the machine power supply as PDB has its own power. Of course, the standard PDB operation is still the same, if power got lost, then it returns (if it was released) also if air-pressure lost. The same limitations as before.

Digital Load Meter: The 2nd Mod which now required to tell PDB not to operate. I checked if the Tormach control board provide output when the spindle is running, but no such output found, so the only way to know the spindle is running is to use the provided signal from the VFD standard load meter output.

The VFD provides a perfect load indication output for external use. I could have just connected it directly to the above PDB microcontroller; but I figured as long as I am connecting to the load output, might as well display it. I am just waiting for the 2.2” TFT LCD display to arrive so I can finish the firmware and board for the load meter. This board uses the PDB optical isolated connection when there is a load on the spindle. Hopefully the LCD will be arriving in couple of days and will make a video about it once installed.

Now that this is tested on the machine, I need to make the machine cut the plastic cover to fit the two RJ11's as they stick out of the cover. No difference than my 3D printer which makes part for itself, the 770 is also cutting parts for itself. When I have more time on Fusion 360 I may make a full aluminum enclosure with a magnetic base so it sticks to the back of the column, but then I should keep it outside to be seen, no point of cutting something shiny then hide it

And by the way guys, the single hand operation in the video was not a showoff, its just I was taking a video, I do really use both hands to change

Here is the video…let me know what you guys think, ideas for improvement, flames, all the norm


<span style="font-family: Arial">https://youtu.be/XTAzURYqd9M

[tmarks11]

[FONT=Arial]The mod allows pressing once to release, then pressing again to engage. With a neat feature that it goes back automatically up if nothing happened for 10 seconds (or 20, 30 sec options). This is just so if I got distracted with a phone call or took too long to put the other tool, then the controller pulls back the bar so not to keep tension on the bar

Except you are not supposed to engage the drawbar without a tool in the collet, because it will damage the collet.

I replaced that stupid two button remote with a latching pushbutton. Push it to release, push it again to engage.

Leaving the PDB in the release position does not keep tension on the drawbar (actually the drawbar is tensioned when it is engaged). Leaving the PDB in the release position does keep the bellevue springs compressed, which I suppose can lead to early end-of-life, although probably not significantly.

[narrobb]

Except you are not supposed to engage the drawbar without a tool in the collet, because it will damage the collet.

Yes, that's what they recommend, though the max spacing quoted between the bottom of the cylinder and the top of the drawbar means it won't be a lot more pushed in without a tool, though it is a good practice.

I replaced that stupid two button remote with a latching pushbutton. Push it to release, push it again to engage.

Good call.

Leaving the PDB in the release position does not keep tension on the drawbar (actually the drawbar is tensioned when it is engaged). Leaving the PDB in the release position does keep the bellevue springs compressed, which I suppose can lead to early end-of-life, although probably not significantly.

Ah, yes. The collect is slightly out and the springs are loaded when released.

[TurboStep]

It appears to me there's a growing tendency for engineers to use microcontrollers for everything. Yes, I use them myself, but often there are more elegant solutions. As Tim has pointed out you've implemented a latching pushbutton with a micro-controller, and the PDB lockout can be implemented using an old telephone cable.

In design world; we can’t assume the operator is professional enough to understand and not do certain things; design should be for the village idiot (no pun intended) and goes up from there. Only in the issues that can’t be resolved in design, then we rely on education/training and increase awareness.

You wrote:

So the drawbar will be pushed down even if its rotating 1000’s of RPM! Well, I had to try it ...

and

I got a small ‘visible’ dent to remind me of that

Oh dear. I guess Tormach didn't recon with:

an engineer that been designing control systems for the past 20 years

Next time, just remove the belt

I optimized the firmware so the whole board only consumes 0.5 milliamps.

Why did you need to optimize the power consumption? Did you have any power limitations?

You also wrote:

the only way to know the spindle is running is to use the provided signal from the VFD standard load meter output.

but if you read the ATC manual you'll realize that an output from the VFD is programmed to provide the correct signal, and the PDB board already has the corresponding (isolated) input connection. All you need is the telephone cable. A couple of threads on the zone covered this some time back. Check out :
http://www.cnczone.com/forums/tormac...ml#post1248034
and
http://www.cnczone.com/forums/tormac...ml#post1459808.
These were all based on 1100's but I just checked the 770 ATC documentation and it appears to be the same.

I'm looking forward to seeing your TFT display
Step

[narrobb]

Next time, just remove the belt

Yeah, that should be easier

Why did you need to optimize the power consumption? Did you have any power limitations?

So I don't have to power the board separately. I wasn't sure what pull-up used on their board and I did not want to go take it off to check, so now it is powered by the other button +5V. Seems even if I did not make it lower, we can still get 20mA from that button input.

but if you read the ATC manual you'll realize that an output from the VFD is programmed to provide the correct signal, and the PDB board already has the corresponding (isolated) input connection. All you need is the telephone cable. A couple of threads on the zone covered this some time back. Check out :

No I did not read it. I just got my machine and I started to get involved. Sweet. So I get it the RJ11 would connect from the Analog output of the VFD to the PDB! Will check these out.

I'm looking forward to seeing your TFT display
Step

Finished firmware today, will be done in couple of days and will post here.

[kstrauss]

I was going to post the link to the PDB fix but TurboStep beat me to it! I got an industrial foot switch for my PDB from the local junque yard and love it since it frees both hands: one to remove the current tool and the other to hold the next tool ready for insertion.


I added an analogue load meter (about like the Tormach accessory) to my 770 years ago. Mine sits in a small diecast box on top of the control cabinet. I planned to make a colour LED bar display but haven't gotten around to it. I suspect that an analogue or bar type display is easier to interpret at a glance than a digital display. Also, note that the load may vary dramatically over short intervals. Perhaps display both current and peak load? Please post more details of your load meter when you get it working.

[narrobb]

Current firmware does have a colored bar. These photos on the bench; pending actual installation but so far I have the yellow range starts at 90 and Red to start @ 94 till I see actual data or someone recommends a color band range from their experience.

Thanks for the tip about peak load display. I am going to drop the fractions and add a peak reached value for that run.

I am planning to install mine similar to yours, as there is already a hole for it on top the cabinet and it's the closest place to the VFD.

I was going to post the link to the PDB fix but TurboStep beat me to it! I got an industrial foot switch for my PDB from the local junque yard and love it since it frees both hands: one to remove the current tool and the other to hold the next tool ready for insertion.


I added an analogue load meter (about like the Tormach accessory) to my 770 years ago. Mine sits in a small diecast box on top of the control cabinet. I planned to make a colour LED bar display but haven't gotten around to it. I suspect that an analogue or bar type display is easier to interpret at a glance than a digital display. Also, note that the load may vary dramatically over short intervals. Perhaps display both current and peak load? Please post more details of your load meter when you get it working.

[kstrauss]

Just a thought:
Have you considered displaying the load as a series of vertical bars with time along the horizontal axis and the height of each vertical bar showing the peak during that interval. Each bar would be coloured green/yellow/red to the extent that the load reached that level. The rightmost bar could show the current load.

[narrobb]

but often there are more elegant solutions. As Tim has pointed out you've implemented a latching pushbutton with a micro-controller,

There is better trick; if someone doesn't have ATC, no need to change Tormach button to latching one, pull the RJ11 from the Pendant port (first port) and put it into the 2nd port (ATC). This way the release button can be used to drop, lock button to pull up (This is tested on my 770, as it seems they may have different ATC boards compared to 1100, so for 1100, give it a try)

I knew about this before I did the tiny controller but I wanted time control and spindle load control. Just saw the other two posts, great. This controller and the opto-isolator will come in handy later on when I start a custom ATC board project soon.

Controller boards are more elegant anyway, but that's just me

[narrobb]

Just a thought:
Have you considered displaying the load as a series of vertical bars with time along the horizontal axis and the height of each vertical bar showing the peak during that interval. Each bar would be coloured green/yellow/red to the extent that the load reached that level. The rightmost bar could show the current load.

This screen is 2.2" one, I can use a bigger one if needed but I am also aiming to limit power consumption to 40mA, as it seems the VFD have a 100mA limit (for everything). If it makes a huge difference I can always go dedicated power supply and isolate the board, though the feature would be something that makes a big advantage to the cutting operation.

What sort of time-frame (from left to right) you are suggesting? I've yet to cut anything with a load meter so i am looking forward installing this one as it is and call it MKI and see if MKII needed. I did account for a USB port (but was not planning to install the component at this stage), but the USB port can be used to download data to be displayed or graphed. My intention for it is to upload firmware later on.

[kstrauss]

I haven't considered all of the implications but...
It is probably only relevant to know the load for the current tool so how about resetting things when the VFD starts? Always show the max/min since startup as a fixed width bar at the left. Divide the remainder of the screen into perhaps 60 buckets that show the peak and minimum for the current second and each of the last 60 seconds. To show max/min in a single bar colour in green/yellow/red the area between min and max. The time required for a full screen update every second may be an issue. If necessary you could update the rightmost bar often and perhaps update the other bars every 5 seconds or whatever your update speed permits. Is your LCD connected via i2c, spi or...?

[narrobb]

I haven't considered all of the implications but...
It is probably only relevant to know the load for the current tool so how about resetting things when the VFD starts?

That's what i had in mind, everything reset on every VFD power up. But then again, I maybe cutting more than one job without resetting the VFD after each job.

This LCD uses SPI. It's actually fast, but full screen refresh is little slower. Will be much faster updating numbers (%) and not bars. Keeping one bar (the main one).

I like the idea of showing peak of each tool. Going to look into having few dedicated areas at the bottom of the screen, (for few different tools) and just store there the peak of current run, once the spindle goes to zero then the controller can assume a tool is being changed, and if it's running again then consider that as the next tool and store the peak reached into the 2nd position. And so on as a FIFO buffer.

But if you mean to reset the current peak of each spindle start, then that is a simpler approach; display one current peak time. And when physically changing the tool, then it can be looked at and written down. The controller reset this value when the 2nd tool is changed and the spindle started running again. This way we know the new peak is always for the current tool and we get a chance to write it down before the 2nd/3rd/... ops start. This does not limit the number of tools we can display peak for on the display and still satisfy the objective to take down the peak reached of each tool. So the peak value is going to reset after every spindle start from zero.

I think PP also stops the spindle when changing ops without changing tool? Like if you are using the same tool for Profile op and Pocket op, then spindle stops and starts within a second right? If so, I can fix this issue by using a timing profile within the controller to detect a tool change. .
Thank you for your ideas and input.:cheers:

[mountaindew]

I never purchased the Tormach load meter because it was an analog display type unit. This looks fun, I like bright lights and dig it al displays.

[kstrauss]

I think PP also stops the spindle when changing ops without changing tool? Like if you are using the same tool for Profile op and Pocket op, then spindle stops and starts within a second right? If so, I can fix this issue by using a timing profile within the controller to detect a tool change. .
Thank you for your ideas and input.
[/FONT]

Insofar as I know PP NEVER stops the spindle other than when the operator hits Reset or eStop; the spindle is completely controlled by your gcode. Some postprocessors stop between operations and others do not. I often use Vectric Cut2D for simple jobs and the spindle only stops for tool changes when using normal cutting tools.

There is a problem with assuming that stopping the spindle implies a tool change. For example, I stop and then reverse the spindle for each hole when tapping. Since actuating the PDB removes power from the VFD that rather than zero speed would be a good indication that the tool has changed. It would be great if you could get tool number information from PP but that would be far more difficult and, presumably, requires changes to the Python scripts after each updated version of PP.

Most of the cheap colour TFT boards include a SD card slot so you could archive data there for later analysis. The micro could have a mode in which it reads data from the card and returns it to via USB for analysis.

[narrobb]

Insofar as I know PP NEVER stops the spindle other than when the operator hits Reset or eStop; the spindle is completely controlled by your gcode. Some postprocessors stop between operations and others do not. I often use Vectric Cut2D for simple jobs and the spindle only stops for tool changes when using normal cutting tools.

I see, I've been using Aspire tell I cover some grounds with Fusion 360.

There is a problem with assuming that stopping the spindle implies a tool change. For example, I stop and then reverse the spindle for each hole when tapping. Since actuating the PDB removes power from the VFD that rather than zero speed would be a good indication that the tool has changed.

I think VFD still powered but can't run. I have to admit that I never checked that specifically, but I don't see a reason to remove all power to the VFD itself, it would be power to the spindle. I think the automatic oiler is connected to the same contractor that powers the VFD and that is running all the time unless a reset or eStop is pressed, or the switch is set to Manual. Hopefully I will install it today and test.

[kstrauss]

I think VFD still powered but can't run. I have to admit that I never checked that specifically, but I don't see a reason to remove all power to the VFD itself, it would be power to the spindle. I think the automatic oiler is connected to the same contractor that powers the VFD and that is running all the time unless a reset or eStop is pressed, or the switch is set to Manual. Hopefully I will install it today and test.

I routinely activate my PDB on my 770 just to stop the automatic oiler when taking a break; the contactor (C2?) makes a loud thunk when the PDB is activated. I assume that it is a safety thing to ensure that a momentary glitch doesn't start the spindle during a tool change. It is strange that Tormach would worry about that and not be concerned with a PDB activation when the spindle is spinning!

[narrobb]

I routinely activate my PDB on my 770 just to stop the automatic oiler when taking a break; the contactor (C2?) makes a loud thunk when the PDB is activated. I assume that it is a safety thing to ensure that a momentary glitch doesn't start the spindle during a tool change. It is strange that Tormach would worry about that and not be concerned with a PDB activation when the spindle is spinning!

Interesting. I wanna say I am 99.99% positive it is not the case in my machine, but considering I am new to the machine so I will wait till I check it later in the afternoon.

I don't hear the usual loud thunk when I change tools, I only hear it when first thing I bring the machine out of eStop and press the start green key. If they are really using the Contactor every time using the PDB then that's not really a good thing on the Contactor!

Maybe you can check this with the cabinet door open. I am also fully sure I also did change tools & run the spindle when the cabinet door is opened while I am observing things, and measuring voltages and checking stuff (just part of me checking it out and learning about it so I can add-on my own circuits). I am assuming you only added the RJ11 to VFD Interconnect?

The problem with these Contactors, you never know if its intended to switch off, or its actually tripping/fault. Though actual contactor design would be to use it first thing when you power on and when tripped/eStop used.

You may have a ground loop back and whenever you activate the PDB, it trips the Contactor; are you by any chance have the 12V power supply connected to Monitor/Computer outlet to the bottom of the control cabinet? Or you have it connected directly to its own wall socket? To me it looks your PDB is not isolated from your machine power.

[narrobb]

Got curious so I checked my videos again and I can't hear any loud noise similar to the contactor going off. So how do you put it back on after changing tool for a job? Just Cycle restart will put it back on?

[narrobb]

Actually scratch the above, I got to check it out really. I suppose if opening the motor door would also trip the contactor!. Not sure why the approach is that way. The VFD should have a digital input to hold it from running even if Fwd/Rev are pressed and I think that should be used to prevent the VFD from running the motor, but it should be kept powered. Using the contactor meaning the VFD itself lost power and needs to be restarted and settings loaded again.

If that's the case, then it means my Load meter will be switching off and then back on when tool change! hmmm... This is as it is designed right now to use 24V from the VFD itself. I suppose I can run it from 12V supply of the main board rather, it shouldn't make a difference as the VFD is not isolated from the main board so no need to isolate the load meter if it is also using the main board supply.

[kstrauss]

I need to progress on a project so I don't want to spend much time on this but I did a few quick tests:

Actuating the PDB or opening the spindle door causes the LED display on the VFD to turn off

Perhaps I'm mistaking the PDB piston noise for the contactor releasing.

The PDB is powered from the same outlet as the computer. That said, I assume that the wallwart includes a transformer that would provide isolation. Certainly using a different receptacle should not change things.

If by "RJ11 to VFD" you mean the suggested interlock between spindle active and PDB I haven't bothered to install it.