3M Grinder backing discs

[Slowcoach]

Hi all, recently acquainted two 3m grinder backing discs 178mm and 115mm, and these two pronged flanges (?) have me stumped. The four pronged one is with the 178mm pad and what’s even stranger is the 115mm one only has 3 prongs. Any ideas please?
I thought they might be to align the discs but never found that to be a problem and looking at the fit through the sectors I don’t think they’ll stay in place when removed.
I’ve tried searching online for an answer but failed miserably

 

[Agroshield]

Can you identify any date information on the items? Then you could look in the 3M catalogue for that year.

As 3M are a huge company, they will have technical support resources. If you contact them, you may get lucky. At worst they will be unable to help.

 

[MetalMonkey]

I have the 115 and 125 versions and the nuts that came with mine are just plain flat threaded one each with the two different threads, no flanged washers with pins. Bought about 4 or 5 years ago.
I guess they must suit some sort of pad/disc but I have no idea what.

I would suggest you can probably go ahead and put them somewhere safe, where you can rediscover them in 20 years time.

 

[Slowcoach]

Thankyou for the replies, much appreciated.
I emailed a supplier to ask what they were for and they had to ask 3M and here is the reply.



So after a bit of thinking (not too much) and poking about I measured the holes in the two pronged washers and there is one for the m14 and one for the 5/8 spindles. You just have to swap them over.

Thanks again, not too important in the grand scheme of things but a conclusion.

 

[Agroshield]

Thanks for your research.

Out of curioiusity, which one is the pad fitted with out of the bag?

My guess, because the item is Swiss made, is the Euro-spec M14 one.

That might be why no-one around here knows what the part is for because no-one has ever needed to use that part.

In practice then, the only people who would need the 5/8" one would be 3M's North American customers. And they would know the first time they came to fit the pad to the machine because the 14mm hole would not go over their spindle.