Why was reverse disabled on Burke horizontal no. 4 mill?

I’m reactivating a Burke No. 4 and everything works except the reverse-running things. Yes the only reason for reversing the motor is to run the table back to the start of a cut. I think it can be pushed back by hand so the reverse isn’t essential but I’d like to have it anyway. Two things show it was intentionally disabled, the center contacts of the reversing switch are not connected (green circle) and a steel stop was added to keep the switch handle from going down to the reverse direction (red circle.) Why would an owner (presumably) or operator disable the reverse function? Mill details if interested: http://www.vintagemachinery.org/pubs/132/5821.pdf

Keeps an unobservant operator from ruining cutters.

The Burke number 4 mill, if equipped with the factory-built power feed to the table ( X axis) had no means of reversing the direction of table feed. Possibly, a previous owner of that milling machine did not want people using it to reverse the motor to run the table back while turning the spindle against the cutting direction of the cutters.

Another reason might be the fact the Burke number 4 milling machines are a very light duty machine tool. There are two (2) ways to run work into a milling cutter, one way tends to push the work back against the table feed, and the other tends to pull it into the cutter. I call that latter direction "Working on the hungry side of the cutter". If a lightly built machine tool has a weak setup for holding the work or excessive backlash in the table feed screw's nut, running a cutter in the climbing direction can do a lot of damage in a hurry. Work is pulled into the cutter, possibly pulled right out of a light-duty milling vise, and a damaged cutter or sprung arbor can result just that quick. If the mill were used in a shop where people operating it were not particularly experienced or knowledgable, and if the table feed nut were worn (no backlash adjustment on the Burke mill, solid nuts used), they might try climb milling or at least run the spindle against the cutting direction of the cutters. In a school or manufacturing application, disabling the reverse position on the switch would insure that people could only run the cutters in the correct direction once the machine were setup. If the mill has the handlever table feed (rack and pinion table feed), then this Burke mill was sold for production machining operations.

I had one Burke number 4 mill without power table feed. I built a drive for that mill with a countershaft and 1 HP motor. I did use a reversing switch on that mill, and truth be known, really only ran it in one direction for reasons listed above. I sold that mill and got a Number 4 Burke mill which came out of a school machine shop. It is a nice tight machine. It has the power table feed. Interestingly, the drive on it is a "Master" single phase motor with integral reduction gearing. The motor is repulsion-induction type, so is not reversible with a switch. That mill's motor can be reversed if the brushes are shifted, but there is no need of it. The mill does just fine running in the one direction, and that direction has the cutter teeth pushing towards the table feed crank when running in power feed.

I use my number 4 Burke for odd little jobs such as running slitting saws or deep/narrow slotted cuts. It's a handy little milling machine, but a person has to respect its limitations. As I wrote, I never found need of being able to reverse motor rotation.

When you say the center contacts are not connected, do you mean there are no wires on any of the two center contacts? In other words, just two wires to the motor? If that's the case, it's not a reversible motor. I hate to state the obvious, but I can't tell from the picture.

Irby

For the motor to be reversible, it has to be 3 phase, and has to have 3 wires running to it. If it has only 2 wires running to it, it's 2 phase and isn't reversible. It's that simple. Count the wires running to the motor. You can't run a 3 phase motor by disconnecting one of the wires.

That's over simplified, but essentially true for the switch on this Burke.

If you see the motor plate says it's 3 phase, then the switch must be passing 3 wires to the motor, and the reason for locking out the reverse is what Joe has said. I have a #4 also and use the reverse once in a while. Usually when I have a reverse hand cutter in it, or when I want to switch to climb milling for a better finish. My mill has the screw feed so it can handle climb milling OK if I take a very fine cut.

Irby

IrbyJones said:

When you say the center contacts are not connected, do you mean there are no wires on any of the two center contacts? In other words, just two wires to the motor? If that's the case, it's not a reversible motor. I hate to state the obvious, but I can't tell from the picture.

Irby

Click to expand...

Two center contacts, which if connected would enable reversing, aren’t wired, and in fact look as if they were never wired. Interestingly, there’s a third wire from the on-machine on-off switch box, that goes directly to the motor and not through this reversing switch. That’s how the two remaining wires allow reversing, the reversing switch reverses the line phases to which they are connected between the lever-up and lever-down positions, with the middle horizontal lever position being “off.”

Single phase motors DO reverse, they just don't do it "on the fly", you have to stop the motor first. Then you flip a switch that reverses the start winding, and it will start in reverse. You do need 4 wires to the switch, but they may just be not all used.

Two wires TO the motor are not the problem, it is what wires are available IN the motor, meaning inside the connection box of the motor. The motor must be at least a 4 wire (single voltage) or 6 wire (dual voltage) motor in order to be reversible. You must have separate connections to the run winding and start winding.

If you have a reversible motor, then you can add reversing if you want it. But most single phase motors will NOT do instant reverse. (The ones that will, have a special relay system in them and are not very common.)

Cannonmn said:

View attachment 292262I’m reactivating a Burke No. 4 and everything works except the reverse-running things. Yes the only reason for reversing the motor is to run the table back to the start of a cut. I think it can be pushed back by hand so the reverse isn’t essential but I’d like to have it anyway. Two things show it was intentionally disabled, the center contacts of the reversing switch are not connected (green circle) and a steel stop was added to keep the switch handle from going down to the reverse direction (red circle.) Why would an owner (presumably) or operator disable the reverse function? Mill details if interested: http://www.vintagemachinery.org/pubs/132/5821.pdf View attachment 292261

Click to expand...

What Reggie said about cutters, what Joe said about NOT "climb" milling.

A DC motor for the spindle makes reversing as easy as variable speed, but that's just me and my K-B's



More useful, perhaps?

A reversible - also variable-speed - Dee Cee hollow-shaft Bison (or Bodine) gearmotor mounted back where it replaces the light-duty step-pulleys for driving the universally-jointed traverse-feed shaft.

If you chase that option, you'll still need that rig - shaft and worm. Those motors are too heavy and bulky to mount on the nano-table.

You'd also still need the slotted cover with cam/latch arrangement to be able to engage or drop-out the worm - or have the limit stop in the Tee slot in the front edge of the table kick it out with the pushrod.

ELSE the table cannot be adjusted nor traversed by hand for lack of a dog clutch or the like on the DC Gearmotor.

Previous owner of my one said all he - or his Uncle before him - had done with it for 30 years.. was cut straight or Woodruff keyways.

Nothing else. Didn't even have the power feed shaft or worm.

In fact, he had been powering it through the TAKE-OFF step pulleys MEANT to be FOR the traverse feed - from a salvaged 1/2 HP Rockwell table-saw motor mounted backwards on the swing plate to line its pulley up with the step-pulley on the arse-end of the spindle.

The main Vee belt sheave had gone "empty" of any belting for ages!

It had been all the power they needed, given they repaired motorized lawn and garden goods with relatively small shafts and keyways!

In its "normal" configuration, a #4 with #9 B&S tooling can do what it does at a higher metal removal rate than a Bridgeport with Are Ate.

It may be small, but it is still a horizontal.

Cannonmn said:

Two center contacts, which if connected would enable reversing, aren’t wired, and in fact look as if they were never wired. Interestingly, there’s a third wire from the on-machine on-off switch box, that goes directly to the motor and not through this reversing switch. That’s how the two remaining wires allow reversing, the reversing switch reverses the line phases to which they are connected between the lever-up and lever-down positions, with the middle horizontal lever position being “off.”

Click to expand...

Is your motor the Lima 3 phase with the 4 speed gearbox? In that case I'd just wire the switch for a standard reversible setup. It's handy when needed. The manual you linked to just shows the single phase gearhead motor and it's switch connections. The switch connections for the Lima motor are different. Someone here may have them, and I may be able to get them off my mill for you if needed.

Irby

IrbyJones said:

Is your motor the Lima 3 phase with the 4 speed gearbox? In that case I'd just wire the switch for a standard reversible setup. It's handy when needed. The manual you linked to just shows the single phase gearhead motor and it's switch connections. The switch connections for the Lima motor are different. Someone here may have them, and I may be able to get them off my mill for you if needed.

Irby

Click to expand...

Thx, my motor is definitely 3 phase but based on the possible bad things that can happen in reverse as opposed to the slight benefits, I’m going to leave the reverse disabled for now.

If my memory is correct since I haven't owned a Burke mill for quite a while. You can't climb mill with one. From what I remember spindle rotation and feed direction is always in the Conventional direction as long as the cutter is placed on the arbor properly. Mounting the cutter backwards will not climb nor will it cut eventually the feed pressure will break the mill. So running the motor in reverse is not a problem as long and the mill is mounted properly in respect to direction of rotation. Reverse may have been disabled so that Mill were always mounted one way.

Cannonmn said:

Thx, my motor is definitely 3 phase but based on the possible bad things that can happen in reverse as opposed to the slight benefits, I’m going to leave the reverse disabled for now.

Click to expand...

At the time I "re-engineered" my one to DC drive - not having the geared-head motor- I had no larger mill. So reverse was added mostly for tapping and use as a horizontal drillpress. Into the end of long wooden goods as much as anything metal. Vertical structural columns, mostly.

You don't clamp these to the tiny Burke. You support them independenty, then wheel the Burke over, adjust tilt, clamp the Burke to the Work!

Wasn't long, I got a bigger mill. AND a much taller drillpress!

OTOH, mine has the "universal" swivel table, so there are still a few things it can do more easily. If/as/when...meanwhile, on wheels, it don't eat much space.

DC Motors and K-B controller are optionable 90/180, so I can as easily run it off either of a decent 120 VAC 1-P outlet, shop, carport, even the driveway, as off 240 1-P.

Hello Hulon here ,
I have a Burke no4 milling machine.with a reversing switch.it has four wires.single phase. The wiring diagram is available. For Burke no4.
Motor shops are also a good place to go .they have a professional inside scope on the way things are. Different from the consumer.
Also take out the guesswork.