Boxford TCL 160

[Saracen]

It turns out I was over-thinking this, as usual.

The inverter direction is controlled by two relays on the old Boxford driver board, one for each direction.
One end of the coil is connected to +12V. Shorting the other end to Ground activates the relay.

Using the Planet-CNC Output Board, I have connected the NC connection of Relay2 to the Boxford CW direction relay, and the NO connection to the Boxford CCW direction relay.

The common connection on Relay2 is connected to the NO connection on Relay1.

The common connection of Relay1 is connected to Ground.

When the Spindle enable signal is active on Output1, Relay1 connects Relay2 to Ground, activating the spindle.

The Spindle direction signal on Output2 determines whether the NC or NO connection on Relay2 is connected to Ground through Relay1, and hence which way the spindle turns.

No other wiring required :D

Adrian.

[Saracen]

Not much movement on the conversion front due to other, more pressing projects, though I do now have the old control panel jogging buttons wired up, so I can move things from the panel, rather than the PC.

Next task is to wire the turret motor control to an Arduino, so that I can use the old control panel "Turret Index" button to rotate and lock the turret once for each press.

Adrian.

[Saracen]

Arduino connected to the turret driver tonight and a quick hack of a program put together.

Three buttons have been programmed; the first moves the turret CW whilst pressed, the second moves the turret CCW whilst pressed and the third moves the turret round 45 degrees and backs it into the pawl.

Seems to work, but a few stutters in the rotation and the locking isn't even amongst the different tool positions.

Adrian.

[Saracen]

Wired up the index opto slot sensor on the spindle shaft to the Mk2/4 board. 12V power comes from the opto isolation board I'm using on the homing switches.

Spindle speed is now displayed, alongside the demanded speed, and they seem to be reasonably close over most of the range.

Adrian.

[Saracen]

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.

Adrian.

[Saracen]

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.

Adrian.

[Saracen]

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.

Adrian.

[keith wainwright]

Hello .I have just purchased to very same machine exactly like yours and it work very well.I have a Planet-CNC Mk3 board and hope to use this to connect to a pc with the planet software Could you help with wiring diagrams , plans or any info at all as i am an engineer and not very experienced at all with electronics. I don't mind purchasing whats needed but don't see the sense in scraping things that work so well. Please help thanks

[DrBrodie]

Hello Saracen,

I work in a school and we have a Boxford 160 like this one. We are having turret indexing issues. I don't suppose you have a diagram of the turret assembly so our technician can strip it down? Only manual I can find is online for £60! Zero chance of school buying that for us.

Thanks in advance,

Neil Brodie

(DrNBrodie at gmail.com)

[keith wainwright]

Hello please let me know the precise problem as I have striped a few of these and I may be able to assist. They are not very complex and parts and diagrams are on the Boxford website.