Here's a list of things I want to get from my mill. They all seem individually doable. I can already use my mill for basic 3D machining.
So, here's what I want.
1) All panel buttons and jog buttons work properly
2) Spindle Speed control from G code using solenoids that actuate the vari-drive (and not VFD), so that I get full power output at all speeds, all the while operating at 60 Hz
3) Flood and mist coolant working, including from G code
4) Jog mode, VFD at 5 Hz
5) 4th (rotary) axis based onthe Troyke CNC rotary table
6) Rigid tapping, based on synchronization to spindle speed (G33)
Once I do all of the above, I think that it wil be a Mercedes Benz level mill, loaded with useful features, with everything accomplished without modifying the hardware of this machine, and without incurring expensive costs.
Iggy, I know this is fun. You have really done well and I am envious. I know this is a hobby and part of the hobby is increasing your skill set, but those six goals cost your time and some money. Yeah, I know, spend to save, but those changes are impractical. I suggest you step back, look at the bigger picture, establish a closure point and do another machine. My two cents. Steve
Hey, I'm with Iggy on this one - 1,3 and 4 are just parts of a proper VFD and CNC installation?
2 and 6 sort of come together once you have a spindle encoder (maybe a fine-resolution slotted opto?) and a few solenoids to work the vari-drive, the rest is just programming and Iggy seems to have that cracked :)
No. 5, the rotary axis will take the machine's capabilities into a whole new ballpark - need a custom gear wheel? program it. Need a custom splined shaft? program it, etc. etc.
Noting but some wiring and EMC2 configuration here.
You need to get your spindle encoder installed for this one since EMC2 will need to be able to measure the spindle RPM if it's going to control the vari-drive. As long as someone has already written the modules to control a vari-drive, the rest is just more wiring so EMC2 can control the up/down solenoid valves (and VFD if you haven't already done that).
More wiring and EMC2 configuration. Nothing more than wiring up a couple outputs to relays to control the coolant pump, and a solenoid valve for mist.
Wire up yet another output from EMC2 to your VFDs speed select input, and program the VFD to select between 5 Hz and 60 Hz based on that. I presume you'll also need to wire an output or outputs to control the gear range shift mechanism.
Install your 4th axis drive, resolver converter, and a home switch on the RT, and configure EMC2.
This should come along with the spindle encoder you need for #2.
More like a nice pickup with all the options. You'll see the "luxury" mills and whatnot at IMTS.
Iggy, you ripped all the original controls out of the machine, that *is* modifying the hardware of the machine.
That's the important bit.
Just the need to spend some time working with CAD and CAM software and milling some wax to get familiar with them.
Our older cnc lathes with gear boxes require a M41 or M42 command to switch gear ranges. Perhaps you could implemnet something similar where the command emits an output you use to shift the sheave. IRRC M41-44 are typical gear change M codes.
Wes, yes, I would like to find some good G code number and then implement it. I got some suggestions on emc-users on how to do it, with comparator elements of EMC. But speed change should only happen during speed change, and not at any other moment, like reversal or whatnot. If I get it to work, it will be much better than VFD, and will let me tap with relatively larger taps.
I have a question, does your lathe have a back gear much like a manual Bridgeport? I've never seen a mill like yours.
To some degree automating the sheave displacement should be lower on your list unless you implement a tool changer. After all, you got to change a tool manually now, not much effort to adjust the sheaves.
Are you planing a tool changer?
As far as keeping the varidrive, I went through a lot of effort to repair the varidrive on my Clausing 6903 so I know where you are coming from. How hard my lathe can work is limited by how hard I'm willing to push the thing.
My Bridgeport Interact CNC mill does have a back gear, lowest it goes is 60 RPM.
Yes, but I could forget to change speed.
Definitely not, too complicated.
My own opinion, after the fact that I did it like you, is that it was too much work and cost for not as much benefit. I did it too. Varidrive on this mill, though, is workin well.
Which model of Clausing is this one? Mine has a back gear, as does every other Clausing that I have seen. On most of the 12" swing ones, it is a knurled knob which comes out of the front of the headstock which you pull out, swing down (or up) and swing back in. But you also have to open the cover over the belts and gears and pull out (until it clicks) a pin coupling the bull gear (big one at the right of the headstock) to the pulley sheaves. With the pin pressed in, the bull gear is coupled to the pulley sheaves for "direct drive". With it pulled out, the pulley sheaves rotate independently of the bull gear (which rotates with the spindle nose). Then operating the lever engages the back gear which is below the spindle instead of behind it as is common for back gears. The small end of the back gear engages the bull gear, and the large end of the back gear engages a gear on the other end of the pulley sheaves. I think (without looking it up) that the ratio is somewhere near 5:1.
If there is a back gear (my Bridgeport Series-I BOSS-3 has one) Add a switch to sense the position of the back gear lever and have the CNC sense that switch to see whether back gear is engaged. The computer needs to know this anyway because the spindle reverses in back gear, and you need to have the computer command the VFD for the opposite direction in back gear.
And even without a back gear -- have the computer sense the spindle speed to advise you to change the speed until you get it all automated.
I would *like* to have one, but I agree. You would also have to change the spindle to one which accepted the CAT/BT styles of tool holders instead of the NTMB/NMTB (one of those is right. :-)
And as long as it is kept in good condition (replace the Delrin bushings in the movable pulley halves, and the Delrin-covered steel key which rides in a keyway in the motor spindle -- and I believe also in the mill's spindle every so often.)
Ummm, he's already done the hard stuff, most of this is REALLY easy, just a few lines of HAL code to hook up most of this stuff! REALLY!
The only thing that requires some work is adding an encoder to the spindle. What the heck is impractical? Jog on the VFD is just one more SSR connected to a terminal on the VFD. Most of the mist vs flood is just a couple of SSRs that drive a solenoid valve for mist and turn on the pump for flood. VERY easy, everything except the actual SSR is already present in EMC. G33.1 rigid tapping is already supported, too, and I have it on my Bridgeport as well. Works like a charm! The spindle speed scheme to seek the right speed with the air valves has already been done, I think, and just needs a little bit of adapting to make it work. Iggy's a software guy, so this shouldn't tax his abilities at all. Spindle braking by VFD is easy, it is just setting some parameters in the VFD. Actuating the brake in the head is just another air valve, and either rig it to a delay, so it engages the brake a couple seconds after a spindle stop, or add a button to the PyVCP (virtual control panel) to add a manual brake. Or, for the sole purpose of locking the spindle for tool change, it could be a manual-only button.
You need to remember that there is a standard G-code, really S code to set the speed of the spindle, and you implementation should properly handle it. If the code says S1500, followed by M03, that should be all that is required to start the spindle turning at 1,500 RPM. All the code/script to start the spindle and adjust the vari-drive to the correct speed needs to be hidden, so that there is nothing more than a delay on the M03 while the spindle is brought to the correct speed, before G-code execution continues.
The same can also apply to the high/low gear change, where the background script can handle the high/low gear change transparently as needed, i.e. set a threshold for the commanded RPM at which point the high/low gear change occurs. There is no reason to have to add gear changes to your G-code, when you already need special background routines to handle the speed setting of the vari-drive.
PeteC, all I read about speed changes, makes it seem that it is difficult to change speed by means of varidrive, within the regular HAL logic.
However, I realized that it is a very easy way to do by means of miscellaneous codes M100-199. Those codes are implemented in EMC by means of scripts with ame names, living in a certain directory. Those scripts. in turn, can get access to workings of EMC by means of command "halcmd".
So, I wrote a speed change perl script. It is UNTESTED, because I am away from home. But here it is.
It may be summarized as follows:
- if spindle is not running, start it and wait 1 second.
- calculate acceptable boundaries for actual speed.
- If speed is below acceptable boundary, turn on SPEED INCREASE solenoid.
- If speed is above acceptable boundary, turn on SPEED DECREASE solenoid.
- Assuming speed needed changing, wait up to 20 seconds until speed is "in range".
- If after 20 seconds speed is in range, good, otherwise bad.
- if spindle was not running prior to this code, stop spindle and wait until VFD stops is.
The advantage of this approach is that it is done in a totally self evident script that can be debugged. The disadvantage is that S300 reads better than M141 P300. But I can live with it and leave S command control VFD speed, which I do not really need to do with varidrive that much, but just to look cleaner.
#!/usr/bin/perl
print STDERR "$0: " . join( ',', @ARGV ) . ".\n";
sub Kaput { my ($msg) = @_; die $msg; }
sub get_hal { my ($signal) = @_; my $out = `halcmd getp $signal`; chomp $out; return $out; }
sub set_hal { my ($pin, $value) = @_; system( "halcmd setp $pin $value" ) && Kaput( "Could not halcmd $pin $value" ); }
my $P = $ARGV[0]; my $Q = $ARGV[1];
my $min_speed = 60; my $max_speed = 4200;
my $min_delta = 5; my $pct_delta = 0.05; my $time_limit = 20; # seconds
I suspect your code will need some tweaking to account for lag time in vari-drive response so it doesn't overshoot the target speed, i.e. only turn on the up/down solenoid for 1 second, then turn it off and wait a second for the drive to stabilize before checking the speed and determining if it needs more adjustment.
There must be a way to hang this code off of the normal M03/M04 commands so that the machine will operate more or less normally relative to other CNC mills other than a bit slow spindle start when changing speeds. I can't imagine that EMC2 has a limitation that would prevent this.
Pete, I am not speaking from any kind of knowledge. I think that I found way to change spindle speed that I understand. There may be a cuter aproach that I do not yet know. But I found something that I personally find workable.
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