Why would you use a Drum Switch?

[Wayfastwhitie440]

I understand the purpose of the drum switch, but I cant see using it on anything other then a drill press. I've seen them on both metal and wood lathes, but why? WHY would you want it to rotate in reverse when the cutting tools are meant for the forward. If anyone can clue me in that would be great. Thanks

 

[quietsailor]

Cutting threads - some of my lecturers liked to bring the tool off the metal, then reverse the lathe with the power feed still engaged to bring the tool back to the start point on the x-axis/main feed (I'm Irish, I'm not sure if you use the same terms in the states?)

There is another use for it but I just can't remember right now, I'm on a night shift and too tired

 

[Wayfastwhitie440]

I haven't got into cutting threads yet. I still need to get the gears for it. Plus the knowledge, never even seen how to cut threads. I could kinda see where you would use a drum switch.

 

[gloveman132]

There are too many reasons to run a lathe in reverse to try to explain, but it is critical to many operations.

For example, I recently needed to cut an 8 degree angle on a part that was too large to feed from the front, so I reversed the lathe and cut the angle in reverse using the compound.

 

[Wayfastwhitie440]

I guess this will be something I learn as a I go then. I just got into machining so still a lot to learn

 

[JoeFin]

If you run a carbide insert in reverse even for a tiny fraction of a second - its breaks off the edge - don't do it

 

[justanengineer]

A big chunk of the reason lathe manufacturers got away from threaded spindles almost a hundred years ago is so you can run a lathe in reverse. I run mine in reverse cutting on the backside of the part frequently, among other reasons, I like to single-point thread in this manner so Im working away from the chuck rather than towards it.

 

[Deadhead]

There are too many reasons to run a lathe in reverse to try to explain, but it is critical to many operations.

Gloveman is spot on correct. One of the main reason I run one in reverse is if I am using a file to deburr a spinning part. If something were to catch, (file-chuck interface) it will throw the file out the back of the machine instead of through your head-gut-groin (pick one)

If you ever get to the point where you get to play with a CNC lathe, you learn that there is no true forward or reverse, it really becomes clockwise and counter clockwise and you better have the tool oriented correctly or you can tear up stuff fast. . It was always fun to watch a young programmer standing there trying to picture it in his head what he wants the machine to do. Had that look on their face like a cow looking at a new gate.

Seen one guy destroy a $800 dollar 1" solid carbide drill because he programmed the spindle in the wrong direction. Boss switched to using indexable spade drill inserts after that. You can buy alot of inserts for the cost of one drill.

 

[Guster]

One thing to realise is that the tool or cutter is not limited to be mounted in the fashion usually described in textbooks. Once you realise that you are open to a wealth of options and possibilities that extend your capability or save a lot of fussing.

Just this morning I had to cut an internal o-ring groove in a small diameter part that would have been otherwise demanding if not mounting the tool upside down and cutting on the back of the part with the machine in reverse.

Even on a mill it saves on extensive cost of tooling that would otherwise limit capability ie. right hand boring bars for using a micrometer boring head to do OD machining.

 

[theknurl]

if you buy an Apex 16" disc grinder with a reversible Baldor motor.....

you toss the stock on/off switch and mount a drum switch.....I did and it's VERY handy

 

[steel 35]

if you buy an Apex 16" disc grinder with a reversible Baldor motor.....

you toss the stock on/off switch and mount a drum switch.....I did and it's VERY handy

While I was tracking a noise in my 12" sander today I remembered you saying that before and looked at the motor I have and was afraid; I have wired 3 in the past but not with a motor like this.

 

[Wayfastwhitie440]

Now can a drum switch be mounted to a type of motor or only particular motors. I know there's different switches for different outputs.

 

[Zeke]

The motor has to be reversible. You are just reversing the wiring diagram inside the switch.

 

[OccupantRJ]

For power tapping on a lathe.

 

[hunter1151]

Some older lathes when put in back gear have to be reversed.........

 

[Guster]

Now can a drum switch be mounted to a type of motor or only particular motors. I know there's different switches for different outputs.

Reversible motors basically allow you to change the polarity of the start winding in relation to the run winding changing the direction in runs in. Two position drum switches basically allow you to wire the pole change on the start winding so you can reverse it with a switch.

 

[Kevin54]

There are too many reasons to run a lathe in reverse to try to explain, but it is critical to many operations.

For example, I recently needed to cut an 8 degree angle on a part that was too large to feed from the front, so I reversed the lathe and cut the angle in reverse using the compound.

If you run a carbide insert in reverse even for a tiny fraction of a second - its breaks off the edge - don't do it

For power tapping on a lathe.

Some older lathes when put in back gear have to be reversed.........

^^^^This, this, this, and this^^^^

And yes, JOE FIN.....running in reverse with a carbide toolbit will snap it. It will also dull a HSS Bit. In the case you are thinking, you reverse your feed, and not head rotation.

Just the other day, I had to custom make some rivets. I was using a 5/32" radius tool. With the way the flutes are on the tool, and the way I had the tool set up, I had to run the headstock in reverse with the tool on the backside of the part.

ANd a lot of times, depending on the size of the part, it may dictate that you have to run on the backside in reverse.

One word of caution....if you find that you have to run a part in reverse, with your tooling on the backside. Make a couple of dry runs so you know which way to start out when turning things on. Hang a post-it note by the switch on the mill. In a lathe, when I was training one person, I actually took a piece of string and tied the lever to the compound. Pushing the lever down was forward, pulling the lever up was reverse. He had one chance to make the part, and he was known to screw things up from time to time. A simple piece of string kept him from pushing the lever down.

I can run a mill or lathe practically blind, but I always have Post-it notes for myself, to remind me of a dimension and such. I snagged the wifes labelmaker and had to make a label reminding me to release the brake on my Lagun Mill before starting. I have a toothed handle to lock the brake, and if I kick the mill on with the brake on, it slides the belt in the pulley. Now a simple note fixed that problem. The best machinist or toolmakers out there will always have notes scattered here and there as a reminder.

 

[Kevin54]

Here is one example why I had to run the lathe in reverse. And along with a lathe, if you are rigid tapping using a mill, it is a necessity to be able to reverse it rather quickly.

This is running the lathe in reverse so I could see the cutting edge of the radius tool. I could have turn the tool -90 drgrees, but I did not have clearance between the chuck jaws and the tool, to be able to cut the head of the radius. That left me no choice other than running it in reverse.

 

[Wayfastwhitie440]

The motor has to be reversible. You are just reversing the wiring diagram inside the switch.

How can I tell if a motor can be reversed?

 

[rlitman]

When boring on the lathe, if you run it forwards, you cannot see the cutter. You can see clearly in reverse, because you cut off the back side of the opening.

 

[Zeke]

How can I tell if a motor can be reversed?

It will say on the label or inside the connection cover. Lots of information on the inside of the cover on motors.

 

[Wayfastwhitie440]

It will say on the label or inside the connection cover. Lots of information on the inside of the cover on motors.

Awesome thanks a bunch

 

[Kevin54]

At work, we had one set of gang drills that one of the other guys had the maintenance put a drum switch on so he could rigid tap on the drill press. DO NOT TRY THIS AT HOME!!!

Rigid tapping in a mill is way, way different than rigid tapping in a drill press. For one, in a mill, your piece is clamped in a vise that is bolted to a table.

A drill press...it will **** that drill press vise up off of the table and swing it around, snapping your tap, damaging your part, and if you are lucky you will avoid injury. As soon as the guy retired, I had the drum switch removed.

Some people think that a mill is a dangerous piece of equipment....a drill press will do more damage to you than a mill has ever done.

We actually had to get rid of some drill presses at work because they were gear driven presses and not belt driven. Not sure of the name of them right now. But they were replaced with a belt drives because if something got caught, the belt would slip eventually. Gear driven....it keeps going until something breaks or something comes off. The reason for the replacements were that a person was counterboring a hole, in sheetmetal, with gloves on, and no fixture to hole the part. No.1.....you don't counterbore sheetmetal, No.2.....ABSOLUTELY NO GLOVES and No.3....always have a fixture if possible.

He broke all three rules and using the counterbore in sheetmetal, the sheetmetal caught, which caught his glove, which in turn pulled his thumb completely off. The docs were able to reattach his thumb, but it doesn't work correctly.

Now I do have to admit, when I was working with large dies and had to drill parts in the drill press, I did break the rules a few times and did have gloves on. The gloves were to handle the dies and the sharp pieces on it, but at no time would I let my hand near the chuck until it completely stopped. So I admit, I did press my luck, but was lucky in doing so.