Can anyone help me identify a replacement switch.

SShep71 · Feb 10, 2020

I know this is a momentary rotary switch with 3 positions fwd/off/rev for a motor on my Grindingmaster wide belt sander. It controls the table motor that raises/lowers the table. I am trying to find a suitable replacement that I can receive and install in the next few days, not wait for something from Germany. Can anyone out there identify anything, I am really hoping to not have to redesign everything to accept a replacement.

awander · Feb 10, 2020

How many terminals does it have? And how are they marked?

Does it fit though a hole in a panel or something, and get held on by a nut?

What size is the shaft for the knob?

What are the specs on the motor that it controls?

How many wires were attached to the switch?

Is it a momentary or a maintained switch?

How large is the switch body?

awander · Feb 10, 2020

SShep71 · Feb 10, 2020

Here are some better quality photos, I can't zoom in or the text becomes blurry. The motor can't be anymore than a 2 HP motor, it is a right angle motor that drives the 4 acme screws that lift the table on the four corners. I have seen the motor in the past but never took down the specs. I run the machine at 230V, but it can be run at 480V if tapped properly.

How many terminals does it have? And how are they marked? 10 total terminals / Marked:SRUV 6 unmarked(however there is a missing sticker)

Does it fit though a hole in a panel or something, and get held on by a nut? Mounts to the back of a panel, held in with 4 bolts

What size is the shaft for the knob? 6mm hex shaft (the control knob had to be destroyed to remove the switch, a new one will be made)

What are the specs on the motor that it controls? I do not have the specs, I can't even get to the motor as I can't raise the table for access

How many wires were attached to the switch? 6 wire connection, at SRUV and two unidentified poles

Is it a momentary or a maintained switch? Momentary

How large is the switch body? 56mm body

awander · Feb 10, 2020

Well, again, based on the limited info, it looks like it is a 3-phase switch, so you could probably use one of the ones I linked, the smaller momentary one.

The terminals to use are probably the UVW for the line terminals, and the RST for the motor. T and W appear to be unmarked.

You could identify the Line terminals by powering up the machine and carefully measuring for a voltage on the wires-you should get voltage between any 2 of the U, V and W wires, and nothing on the R, S and T wires.

Rollerman · Feb 22, 2020

Replacement Switch

American Solenoid, Brunswick, NJ Could probably build you a new switch.
They make special switches for me. Talk to Chris Meminger

WizardOfBoz · Feb 22, 2020

I'd be leery of buying a replacement on the basis of the pictures provided. Do you have a wiring diagram? If this is a switch that is momentary both ways, you could find push buttons with the same terminal arrangment and have one "raise" and one "lower". That's what later versions of Grindingmasters had. If you can't get an exact replacement, or the exact replacement is insanely expensive, a two-button arrangement might be even better than the dial-type switch.

jim rozen · Feb 22, 2020

It's *always* the germans who put stuff like this in their equipment. Complete unobtainium. Probably
even from the manufacturer. Oh, those were only used for one or two years.....

steve45 · Feb 22, 2020

It looks like you can probably take the switch apart and clean the contacts. It may work until you can find a replacement, it might even last for years.

Just take pictures as you go, and don't let any springs go flying out!

trevj · Feb 24, 2020

Yep. Open it up and have at!

A silver dime and some solder will go a long ways to making some really durable contacts!

gustafson · Feb 24, 2020

trevj said:
Yep. Open it up and have at!

A silver dime and some solder will go a long ways to making some really durable contacts!

Silver Dime!

what is this 1964?

seriously, most are worth more than their weight in silver

WizardOfBoz · Feb 24, 2020

A silver (~90% silver, ~10% copper) dime can be had for a couple of bucks (and up, depending upon year, mint, condition, etc) on ebay.

trevj · Feb 25, 2020

gustafson said:
Silver Dime!

what is this 1964?

seriously, most are worth more than their weight in silver

Today, a Roosevelt dime, at 90 percent silver content, is worth a buck thirty two. A dollar and thirty two cents, US, in silver content.

So, you were saying...???

Seriously. Whats an unobtainable switch worth? I know that the crappy plastic reversing switch on one of my lathes, IF you can find one, is several hundred Euros!

U.S. Silver Coin Melt Values | Silver Dollar Melt Value | NGC Shows the melt values of silver US Coins. Just in case you were losing sleep over the potential losses! LOL!

Junk silver coins (worn ones, not otherwise collectible) buy and sell for very little over spot, and almost everyone I know that has two brain cells to rub together has at least a few old coins around. You sure won't buy any silver sheet anywhere near as cheap.

It makes good contacts, it's cheap enough raw materials, and it solves the OP's problem, if he is willing to go down that rabbit hole.

pops2004 · Feb 25, 2020

I had a switch similar to this that came off a metal lathe made in Taiwan years ago. It finally gave up. It just wore out so bad it was to far gone to fix. I used a barrel switch to take the place of what I had. It is 220 volts, three phase. Worked fine for me.

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SShep71 · Feb 28, 2020

Well while I don't have much input about the silver dime, I can say that the original switch wasn't a contact issue. There was clearly a "something is broken off inside" mechanical feeling and I had to practically deconstruct the universe to remove the handle from the switch and the switch from the machine. I got the replacement already, I just haven't installed it yet, it is on my things to do today list.

steve45 · Feb 28, 2020

Good! Did you get an OEM switch, or something else that you'll have to 'make work'?

bigwave · Mar 20, 2020

steve45 said:
It looks like you can probably take the switch apart and clean the contacts. It may work until you can find a replacement, it might even last for years.

Just take pictures as you go, and don't let any springs go flying out!

If you can find a switch from the same manufacturer on ebay, you can get a NOS switch and cannibalize the guts for fresh contacts.
I'm doing that with at Kraus & Naimer (bizarro 16-pole reversing switch with 5 positions) for my lathe right now [eventually it'll get a vfd but for now I'm reworking the stock nightmare]. It's a royal pain but possible. Use white electrical tape to hold the stack together as you work on it and get a sharpie to mark/register the relative positions of everything and take a picture every step of the way. They will spring apart (at least the K&N ones do). I imagine these were built by an engineer sorta like the character Gru from Despicable Me -- designed to inflict maximum frustration..

Good luck,
Dave

pops2004 · May 13, 2020

Dave,
years ago I had a milling machine with a strange switch on it that was giving me problems. Smart old me was going to just take it apart and clean the contacts, put it back together and done. How hard could that be ?? Right! Well when I opened it up little tiny springs and pieces flew everywhere. I just very “calmly” threw the remains in the trash and had to fabricate something that would work. The way that switch was made it controlled three different functions I found out. The machine now has three separate switches!!

Oh well. May not look good but it does work.
Barry

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Can anyone help me identify a replacement switch.

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