Meddings MF4 reverse switch

[vwmark]

Hi - can anyone help? Bought a 3 phase Meddings MF4 pillar drill off a friend very cheap. Was told that reverse had stopped working but thought it would be a simple repair!

I have removed the switch but cannot see anyway how the switch could reverse the phase. Switch is original so must have worked once.

Help!

 

[brightspark]

why would u want reverse anyhow on a pillar drill ??

 

[Tigman]

to get it onto the drive !

 

[rtbcomp]

This is the sort of circuit you are trying to achieve

 

[Spark plug]

If it's like my meddings the reverse if for tapping, the switch is actuated by the depth stop, there is also another switch at the top of the stroke automatically reset the direction to normal when the quill is returned to the top of the stroke.

The switches control some reversing contractors / relays in the control box.

 

[vwmark]

Aatached a picture. Mines doesn't have any wiring to the depth stop. The wiring was from an ancient oil dash pot overload switch to the forward reverse switch and then to the motor.

Measuring across the contact there is no difference between forward and reverse.

 

[brightspark]

i wouldnt bother how often do u use the drill for tapping ?? just buy a tapmatic if your doing production work

 

[vwmark]

I agree but just want to know how it works and because it will drive me mad everytime I look at it.

 

[rtbcomp]

Get a meter and trace the connections on the switch with reference to the diagram I posted above.

If they don't match draw up a table of how they do work and we'll see what we can work out.

 

[vwmark]

I have traced the circuit and the switch cannot change phases, just wondered if something was missing off the switch. Definetly nothing on mine electrically on the depth stop and looks like nothing is missing.

 

[rtbcomp]

Can you tell us which contacts are closed and which are open for each position of the switch?

 

[vwmark]

Hi - finally got into the workshop to take a better picture. The switch is a straight rotary switch. Measuring across the contact its either on or off yet the switch states reverse and this model has reverse. Confussed.

 

[Paul99]

I'm no electrician but that would be right. It's not a simple case of reversing the polarity of the motor to make it run in reverse - you need a motor that can be wired for both directions AFAIK. One set of contacts send power to one wiring on the motor the other set of contacts send the power to a different wiring. As such you'll only ever see that the contacts are on or off. My M4 has the same switch but doesn't have a reversible motor so the reverse side of the switch is not wired up.

 

[rtbcomp]

As asked previously, can you draw a table of which contacts are open or closed in each position. Does it have the original motor? Have a look under the terminal cover, it may give the wiring configuration.

 

[the artfull-codger]

It never fails to amaze me how many people who buy pillar drills & want/need them to reverse,& as for tapping well anything over 5/16" & the ordinary jacobs type chuck just hasn't got the gripping power on the hard shank of the tap & an allbrecht does not like reverse [it slackens off]. as B S says above why would you want reverse?

 

[Sidewinder]

To reverse a "standard 3ph squirrel cage motor" all you need to is swap over two of the incoming phases.
It will not cause damage to the "motor".
You need to be sure about the attached mechanics though.

 

[Sidewinder]

It never fails to amaze me how many people who buy pillar drills & want/need them to reverse,& as for tapping well anything over 5/16" & the ordinary jacobs type chuck just hasn't got the gripping power on the hard shank of the tap & an allbrecht does not like reverse [it slackens off]. as B S says above why would you want reverse?

L/H drill bits for removing broken bolts!

 

[vwmark]

I want reverse because the drill has reverse. I doubt I will ever need reverse but its just annoying that I cannot work out why!

The motor is original and switch is original. Wiring is as cut in the picture.

L1 connects to n1
L2 connects to n2
L3 connects to n3

No difference in the connections between forward or reverse.

anyone have a picture of a "working" switch just to confirm they are the sam?

 

[rtbcomp]

The manufacturers must have thought it worthwhile to fit reverse.

Those connections suggest a 3 pole single throw switch. For 3 phase I would have expected something like

Forward
L1-n1
L2-n2
L3-n3

Reverse
L1-n1
L2-n3
L3-n2

I wonder if someone has changed the switch mechanism but kept the original knob & escutcheon.

 

[Spark plug]

Dose the switch have 3 positions? Are there any other terminals around the switch that army used?