Replacement Start/Spindle Range Switch Source?

[Mr. Technical]

Hi Guys,

I have a Series I Boss 6 BP mill. The spindle will not start after I was poking around in the Manual Starter Assembly box in preparation for a retrofit. All of the connections from the wire to the contactor are good, but continuity tests of each side of the Spindle Range Switch show that they're flaky internally. My BP manual lists the part number as 11-50-7873, and each contactor says "Sylvania 300V Max 100MZAA" on it, but I haven't been able to find a source for either part number yet. Anyone know of a source for an exact replacement, or even an equivalent? Thanks!

Ian

[cncsnw]

You should be able to find a functional equivalent from Automation Direct. I am guessing it is a 3-position selector switch (center off). Probably needs normally-open contacts on each side. You will need to note whether it is a "maintained" selector (stays where you put it) or a momentary "spring return to center" type.

Browse:
http://web1.automationdirect.com/adc...on-Illuminated

Good luck.

[Mr. Technical]

Thanks for the reply. I did a little more digging, and it turns out this is actually a 5 position switch, and Bridgeport/Harginge don't carry it anymore. One tech told me that years ago he'd replaced one of these switches with a 3 position switch and some relays. Does anyone know what that circuit would look like? I'm thinking of starting with this switch from Automation Direct (GCX-138022) http://web1.automationdirect.com/adc...ted/GCX1380-22 Any more help out there?

[cncsnw]

Can you summarize for us what the five positions are, and what happens with the controller/machine in each position?

[Mr. Technical]

I'll do my best!

This is a 5 position switch that is OFF in the center position, has a continuous pole to either side of center, and then has a momentary pole to the far outside on both sides. Each half of the switch has poles that look like this: 1 -I/I- 2 (NC poles) and 3 -I I- 4 (NO poles). So it's 2 NO Poles, and 2 NC poles. It's a panel mount, and is rated to 300 VAC. To start the spindle in Forward/High Speed mode you turn the switch to the far right and release it. It then spring returns to near right. To turn it off, you just return the switch to the center position. Reverse/Low Speed is the same except for the direction that you turn. (Far left, release switch and it returns to near left, until you turn it off). Here's a schematic Darek posted that might help. It's for another model BP, but what's shown looks the same as mine. Hope this helps, and thanks for taking the time!!

[Al_The_Man]

You should be able to do this quite simply one of two ways, the first with a 3 posn. Mom. L/R and center off switch such as Telemecanique/Square D etc, and just stack contacts as needed.
It also would be fairly simple to do with a 3 position single contact switch if you intercept the wiring at 219 221, and have these conductors controlled by two small multi-contact relays, these would be fed from the latter switch and they in turn would feed the Hi/lo contactors.
IMF IMR, strangely they are marked as one would For.Rev rather than two speed?
The interlocking would be done by the small relays instead of the single multi-contact switch.
Looking at the diagram again, the switch appears to be L/R maintained, not momentary?
Al.

[Mr. Technical]

Hi Al,

Thanks for the input. I took a closer look at the schematic in my manual, and see some differences from the schematic I posted earlier. In the interest of full disclosure , here's a scan of my manual's page. I hope it's legible enough for you.

In reference to Forward and Reverse and High and Low: The placard shows High and Low speeds, but the positions are really (also) Forward and Reverse. The reason for that is that you have to throw a mechanical lever to engage the back gear. Once you do that the spindle direction is reversed mechanically and much slowed of course. So if you want the cutter to move CW in back gear, you need to tell the motor to turn in reverse by putting the switch in Low Range (Low=Reverse). The opposite is true of course for regular (no back gear, CW) use (High= Forward).

Can you let me know if you think that the suggestions you made above based on the old schematic would apply to the new one? Thanks again!

Ian

[Al_The_Man]

The fact that both contactors are interlocked means only one can be picked up so with just two 'operators' you should only need a 3 posn. switch, I am not sure why they had that other momentary in there.
The CR7 is a spindle enable relay when the enable PB is operated.
I would have to study it a bit further, but there should be no reason why you would have to have a 5 posn switch just to enable either contactor.
The auxiliary relay idea should be viable, even if the single 3 posn switch will not work.
When I get a chance late I can look it over more closely.
Al.

[Mr. Technical]

Thanks Al, I really appreciate the help!!

[Al_The_Man]

Studying the schematic it appears that with the Spindle switch in the left or right position the circuit is not armed until the Spindle Enable button is pushed as the contact on CR7 supplies power to the 1MF/1MR and latches the enable button in?
This would be unlatched when the switch is at centre.
I have come up with a Switch or Relay circuit which in effect should do the same thing, unless there is something I am missing.
Is this Spindle Enable a safety feature?
Al.

[Mr. Technical]

You got it. Here's the description in the Boss 6 manual:

"Use the following procedure to start the spindle:
1)Turn the spindle selector switch on the spindle control panel to either the high range or low range position.
2)Press the spindle enable button. The green light will turn off.
3)Turn the spindle selector switch to the start position.

This will start the spindle. The green light will remain off as long as the spindle is turning or enabled (if the spindle is in neutral, the light will be off but the spindle will not be turning)."

The spindle enable relay was an add on that was supposed to be done in the field, but I don't see the spindle enable button anywhere on my mill. I don't know if that adds to the confusion or helps. To clarify, my mill should have an enable button and spindle off light in one, but it hasn't been updated yet apparently, and all I have is the spindle off light.

[Al_The_Man]

Maybe just the simple way may be the best?
Looks like the spindle enable is used to prevent going from low to high without using the enable button first.
let me know if you need the 3 posn. switch method?
Al.