Thread: Boxford TCL 160
I've decided to drop the Arduino method and just use gcode to change the tools. Much simpler wiring and seems quite straightforward.
However, this lead onto some problems with the turret. Sometimes it would turn and others it wouldn't, either backwards or forwards.
I've stripped it down tonight and found a number of things.
First is that you have to remove the X axis stepper to gain access to the hole through which you release the shaft of the turret stepper.
Having removed the turret and gained access to the cam and pawl, the seemed to be an excessive amount of force required for the cam to push back the pawl.
The pawl tension is adjusted by the screw which passes through a stack of disc springs. Backing that off just a little eased the pressure to the point where the turret rotated freely.
With it all apart, I've taken the opportunity to lubricate all the sliding surfaces.
Whilst putting it all back together again, I found that there should be two alignment dowels between the turret itself and the shaft which powers it. These are missing, so the only thing holding it in place are the four fixing screws. As there is some clearance in their holes, the slop I could feel when manually handling the turret were caused by it slipping on the shaft. Two 5x15 dowels are required to keep the turret true.
Two steps forward, one step back:
After backing off the pawl screw, there wasn't enough tension to hold it in place, so the clack of the turret cam moving round unscrewed it.
Removing some of the springs and tightening it up fully solved the unscrewing problem, but then I found the hole for the screw breaks into the operating area of the cam, so when the screw was fully tightened, the cam caught on the end of the screw.
By adding a brass washer, and adjusting the layout of the disc springs, I was able to get the tension right, and the screw can't unscrew any more as it's now flush with the back face of the turret block, so held in position by the X axis block.
Next, I found that, even after adjusting the tension of the spring, the turret was still stalling at various points. Having tried all sorts of cures, I've had to back off the pre-load on the main cam shaft bearings. Originally, I was too tight to turn by hand. Having removed the shaft, I can't feel any roughness in the bearings themselves, which are BR-7005-2RS angular contact bearings, so I reassembled it with just a smidgen less pre-load than before. It's still tight to turn, and there's no appreicable play or end float, but it now turns on command without stalling.
A little work on the gcode and it looks like an 8.75 CCW turn followed by a 1.75 CW turn is all that is needed to rotate the turret one tool position and lock it back into place.
Hopefully, the 5mm dowels should arrive tomorrow, so I can get the turret aligned and re-installed.
I've already written some simple gcode scripts to make various brass axles. Now the auto-changer is working, I should be able to combine some of them.
There's no homing facility on the turret, so I'll need to make sure that lathe is set to tool 1 at the start of each program.
5mm dowels arrived and have been inserted into the turret. Definitely no play now when trying to rotate the turret by hand, which was noticeable before.
I've written some Gcode scripts to perform tool changes, and am still struggling with getting the turret to a known safe position before initiating a tool change. As the parting / grooving tool stands so proud of the turret, it will hit the Z axis slides if the turret is rotated with the X axis at anything other than near the +ve limit. Still waiting to hear back from Planet-CNC as to why G53 moves are apparently affected by tool offsets, which is why no progress recently.
The TNMC inserts arrived today, so I'll be able to repopulate the original Boxford threading tool, as that is left handed and is easier to accommodate in the gcode I'm writing, and requires less material to be removed to make space for the tool head.
The details are all laid out here:
This is the test program:
% G18 ( Force XZ Plane ) G21 ( Force Metric Dimensioning ) G40 ( Force Tool Nose Compensation To OFF ) G80 ( Cancel Any Modal Motion ) G90 ( Force Absolute Coordinate Positioning ) G53 G00 X60 Z100 ( Move Turret To Safe Position For Tool Change ) G04 P10 ( Pause For 10 Seconds To Allow Notation Of Axis Locations ) G91 ( Force Relative Coordinate Positioning To Stop Turret Reversing To Location ) G00 A16 ( Rotate To Tool Position 3 ) G01 A-2 F100 ( Rotate Back Against Pawl At Feed 100 ) G90 ( Force Absolute Coordinate Positioning For Machining Passes ) T3 ( Force Tool Change For Tool 3 ) M6 ( Force Use Of New Tool ) G43 H3 ( Force Use Of Tool 3 Offsets ) G00 X30 Z60 ( Simulate Program Moves ) G04 P10 ( Pause For 10 Seconds To Allow Notation Of Axis Locations ) G53 G00 X60 Z100 ( Move Turret To Safe Position For Tool Change ) G04 P10 ( Pause For 10 Seconds To Allow Notation Of Axis Locations ) G91 ( Force Relative Coordinate Positioning To Stop Turret Reversing To Location ) G00 A46 ( Rotate To Tool Position 1 ) G01 A-2 F100 ( Rotate Back Against Pawl At Feed 100 ) G90 ( Force Absolute Coordinate Positioning For Future Machining Passes ) T1 ( Force Tool Change For Tool 1 ) M6 ( Force Use Of New Tool ) G43 H1 ( Force Use Of Tool 1 Offsets ) M2 ( End Program ) %
What I'm seeing is that the final absolute position at the end of the program is the "G53 G00 X60 Z100" commanded position, but minus the Tool 3 X offset value. That in itself is odd, but it's also affecting both the X and Z axes, by the same amount. In other words, the final Z position is minus the T3 X offset, not the T3 Z offset:
To get a safe automated tool change, I need to be able to get the carriage to a known safe location, and at the moment I can't do that. Changing from G90 to G91 also seems to have the side effect that the next movement control, on any axis, caused motion on all axes. This usually results in the machine going out of limits, but has also caused a couple of turret/chuck interfaces.
I have just received my Boxford TCL160. I switched it on and from the panel can move both axis, rotate the turret and spin the chuck both fwd and reverse so that's a good sign. The jaws don't open and close even although there are buttons on the panel.
I have purchased the manuals which should arrive tomorrow. These have all the wiring diagrams I believe so if you are in need of any let me know.
I plan also to convert to Mach3 operation so I sure could use some help, any schematics or drawings that you might have and would like to share I would be grateful for.
I would be really grateful for any help you can give.
The jaws require a pneumatic system to operate, so if your lathe has that system fitted, you would need to attach a compressor. Mine has a manual chuck, so I've not looked into that.
The only drawings I have came from a copy of one of the manuals, so you should have that now.
I'm using a Planet-CNC Mk2/4 board to control the original stepper drivers etc, wired up to the original homing and limit switches. It has very limited inputs, so this does mean you lose the use of a lot of the front panel buttons, but I have managed to get the jogging ones connected again.
I'm having problems with the Planet-CNC software, as I think it's designed mainly for routers rather than lathes, so I'm also looking at the Eding controller, in case the Planet-CNC one falls through. Both of these use their own software, so I've not investigated Mach3 for this machine.
Many thanks for the reply Adrian,
No air on my TCL160(1994) so manual only for the chuck.
I have a limit switch on the body of the cabinet which is activated by a rod on the Z Axis. Clearly this serves to prevent the tool post clouting the chuck. (Good idea)
I read somewhere that depressing both Left & Right feed together that the machine should execute a 'Homing' action.
This didn't work for me unless I misunderstood the methodology. Any Ideas ?
Should there also be a Limit /Homing switch for the X axis ?
I purchased a spare set of boards which were removed from a non turret machine together with a Small format Motherboard SBC-GX1 complete with compact flash with Software 4.3.1 installed.
I wonder whether this software can be upgraded to V5 or even 6. Any ideas on this ?
The PC motherboard I'm told was fitted inside a TCL160 ? There is no such board in mine. Did earlier machines have a PC inside ???
For the moment, I will try and get the native software running and see exactly what the machine is capable of doing.
I will then convert it as you have done so if you have any schematics of your arrangement or any pictures that you'd care to share I would be very grateful.
George (Oldham Lancs)
Does your TCL have three or four flexible conduits running from the back of the cabinet ?
If it only has three then it is probably not fitted with homing switches.
I don't believe the PC motherboard fits inside the case. There is a CPU board in there but that's just to read the various switches, take the control input from the serial port and generate pulses for the stpper drivers.
I believe Boxford will sell you a copy of the current software if you let them know the serial number of your lathe. From memory it was about £500 to purchase. I'm doing my own thing now so am not pursuing that route.
Only 3 flexi's so you're probably correct, no homing.
That may impact on the new software.
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