Electrical question

[Danl]

I'm upgrading my mills x axis power feed, a 30 year old Bridgeport model 6f unit, in accordance with the modification shown here:
http://www.atechfabrication.com/info...Controller.htm. This uses a Minirik MM23001C control module.

I kinda like the rapid movement push button switch the way it works now (original). However, this modification changes the rapid switch to a toggle, his particular preference. I'm wondering if I can either use my existing single pole momentary switch in the existing circuit (upper left corner of the image) or put in its place a double pole momentary push button switch somehow. Not sure I like the toggle idea.

Any ideas on retaining a momentary push button switch in the circuit shown? I know one of you sharp EE's in here will have an answer for this.

Thanks,

Dan L

Sorry for the thumbnail... still figuring out how to post photos the new way in here.

[Boostinjdm]

The difference between a toggle and a push is mechanical, not electric. If both are momentary and have the same number of connections, I don't see a not to go with a style you like.

I did not view the diagram. This is just a general opinion.

[Danl]

The difference between a toggle and a push is mechanical, not electric.

The original momentary push button switch has two terminals. He is showing three. Big difference.

[Boostinjdm]

The original momentary push button switch has two terminals. He is showing three. Big difference.

I didn't get to finish. Due to baby interruption. See edit.

[tom_d]

..................or put in its place a double pole momentary push button switch somehow. Not sure I like the toggle idea.

Any ideas on retaining a momentary push button switch in the circuit shown? I know one of you sharp EE's in here will have an answer for this.

Thanks,

Dan L

Sorry for the thumbnail... still figuring out how to post photos the new way in here.

What you need is not a double pole switch, but rather a single pole, double throw switch with contacts: on&(on) The contact in parenthesis being the momentary one. The pink wire goes to the common on the switch. The normally closed pin connects to the center tap on the speed pot, and the momentary normally open pin connects to the grey wire from the speed pot. As has been said before, it doesn't matter if it's a toggle or a push button switch. The contact form and amp rating are what's important.

[Boostinjdm]

I can't make out the labels on the drawing, but it looks like all the switches have both NO and NC contacts. Not sure a push button is available in the size you need, but they are available in larger sizes referred to as push button operators and contact blocks.

A small relay could probably be rigged up to allow use of a more common two pin button.

[CCWKen]

I'm no EE but it looks to me a NO push button could be used between the wiper and the high side. All it would do is bypass the rheostat resistance between the wiper and high side. Done.

[Paul Alciatore]

From what I can see on that small drawing, it appears that his switch is a single pole, double throw (SPDT). You can easily get a push button switch with that type of contacts and terminals. Or a momentary switch in the same form factor as a toggle. They make almost every imaginable type of switch.

The original momentary push button switch has two terminals. He is showing three. Big difference.

[Danl]

Thanks for your replys, guys. I do have a SPDT switch that I can mount which should work in place of his toggle, Paul. I will give that a try.

Here is a larger photo of the original. (I hope)

Dan L

[Mike Nash]

I'm no EE but it looks to me a NO push button could be used between the wiper and the high side. All it would do is bypass the rheostat resistance between the wiper and high side. Done.

That is not such a good idea for a generic statement. Some drives or controls may be OK with it, others may smoke. As shown, the potentiometer is going to be across the potentiometer supply. If the pot is turned CCW and you short the wiper to the CW end, you have shorted the supply.

A rheostat tends to imply a 2 wire connection where the resistance is probably expected to range zero to maximum and shorting would probably work fine.

[Lee Cordochorea]

What Mike Nash said is correct. Look at page 24: https://www.minarikdrives.com/documents/250-0091.pdf - S3 is clearly a supply.

[J Tiers]

I'd be opposed to using a toggle for a rapid, unless it is a momentary toggle.

The momentary (I assume) pushbutton has the advantage for a rapid that you just take off your finger and you are out of rapid. Any sort of maintained operation such as is usual with toggle switches other than momentary, seems like a bad idea.

Is this a separate rapid? It looks more like the type that is the normal movement with a button to change to rapid so long as the normal feed movement is selected. The chance of leaving a maintained contact in the rapid position seems to make it very important to keep the rapid as a momentary. (There are rapids that are a different push button that does not require the regular movement to be selected.)

[Danl]

I'd be opposed to using a toggle for a rapid, unless it is a momentary toggle.

I agree 100%. Made me nervous, which is why I thought I'd ask in here. In his text, the designer said, "I designed the new wiring schematic (below) to make the change over as easy as possible. The only change needed in the switch assembly is that the momentary rapid travel switch needs to be changed to a double throw switch. I ended up using a toggle switch rather than a button so that it will free up my hands while the table is moving."

When my hands are free to get into action elsewhere, my concentration might just be focused on that, rather than on the unstopping table movement.

This controller has settable acceleration/deceleration and braking, if I wanted to add a resistor. At first glance, I was thinking along the line that CCWKen was suggesting, but it didn't seem like a good idea to screw up what would normally be 'seen' across S1 - S2 and S3.

Dan L

[J Tiers]

I agree 100%. Made me nervous, which is why I thought I'd ask in here. In his text, the designer said, "I designed the new wiring schematic (below) to make the change over as easy as possible. The only change needed in the switch assembly is that the momentary rapid travel switch needs to be changed to a double throw switch. I ended up using a toggle switch rather than a button so that it will free up my hands while the table is moving."

When my hands are free to get into action elsewhere, my concentration might just be focused on that, rather than on the unstopping table movement.

This controller has settable acceleration/deceleration and braking, if I wanted to add a resistor. At first glance, I was thinking along the line that CCWKen was suggesting, but it didn't seem like a good idea to screw up what would normally be 'seen' across S1 - S2 and S3.

Dan L

If you can get the "rapid" action you want with a resistor in series with the switch, there may be a value you can use that will allow the connection without threatening to kill the power supply to the pot if the pot is turned the wrong way.

You'd have to see what the safe load on he supply is, and pick a resistor. It might end up too big to give much of a "rapid".

ANOTHER choice, would be to put together a two resistor divider, using the lowest value resistors you can get away with. Then set up that ratio to give the " rapid" action. Now the "rapid" switch will connect tat divider to the pot wiper. If the divider is a lower resistance than the pot by a fair bit, it will over-ride the pot in most positions. At very low pot settings, you might not get much change.

Or, you could just switch from the pot to the divider (or the high side voltage), instead of parallelling them, which is what you show. That depends on what the input does when open, unless you use a "make before break" switch. If there is an issue, you may be able to tie the input to the low end of the pot with a high value resistor to keep it under control while the switch is connected to neither the pot nor the divider (the time it is moving between positions)..

[Danl]

Is this what you are discussing?


There is also a run/jog connection possibility. This controller also has a current limiting LED that turns red when excessive current is detected.

Dan L