Sure there is, I had my machine shop make me an adaptor it looks like this:
I had it made becuse the first 3M UK Backing Plate I was able to get my hands on was the M14 size, actually I forgot all about the different threads from the UK and when it arrived it wouldn't fit
I got the idea of the adaptor from the Metabo extension spindle (I think that's what it's called). Basically what it is, it's just an extension for the Metabo. So I took the spindle extension to my machine shop and told them to make me the exact same thing with the appropriate threads.
I still use the adaptor, it's on my Makita:
It works well, any who the reason why I mention this is becuase it can be done. I didn't have my machine shop make me a bunch of them, in fact I probably only have 3 or so for my self...so dont go thinking that I can provide these for you guys...however, if you get your hands on the Metabo's spindle extension (that comes with the Metabo and I'm sure you can order seperately) you can go to any machine shop and they should be able to re-thread it for you.
Anything can be done, it's just a matter how much your willing to invest in it, time and money wise I mean.