21 Mark II with 5 inch BP?

[MTCarNut]

Has anyone used a Rupes 5" backing plate on the Bigfoot 21 Mark II? If so, how do you like it? How does the machine behave with the smaller bp? What is Rupes official stance on this mod?

It would be nice to have the option of using 5.5"/6" pads for smaller panels where the 7" pads can be cumbersome. Definitely wouldn't want to risk damaging the buffer if the smaller bp puts too much stress due to higher rpms.

Dylan: Your thoughts on whether you think this is a good or bad idea very much appreciated.

[custmsprty]

Lot's of posts on this subject try the search feature, Dylan has also already commented on this subject. Search Rupes Mark II

[custmsprty]

I just did a quick search Rupes Mk II and found this

5" backing plate on the lhr21 mark 2

There are more, search is your friend

[MTCarNut]

Thanks, didnt see that thread searching Google.

[custmsprty]

Thanks, didnt see that thread searching Google.

AG's search, upper right hand side of this thread page, the white block.

[RPM_BR]

I have a 21 ES, and when I put the 5in BP, it becomes a pad eater.
Obviously increases cut, it is like a turbo mode, but a lot more vibration as well, especially sideways vibration.
In mf pad, it generates such a heat that the pad's foam interface melts inside, like b&s black mf pad without center hole.
The Rupes 6in pads on a 5in BP on a 21 becomes convexed, and the center hole opens up like a cone, if you insist in using it. The Velcro durability shortens as well.
Rupes engineers were right when they decided the relation of offset and BP size, spot on.
I'm considering buying a 15 MKII, so I can use 6in pads.
Or buying a Chinese knock off, unfortunately, because a Rupes 15MKII will cost me 1000 bucks .
Best regards

[MTCarNut]

Thanks, think I'll save and just get 15 mkII down the road.

[rlmccarty2000]

Thanks, think I'll save and just get 15 mkII down the road.

Very good idea!

[custmsprty]

I have a 21 ES, and when I put the 5in BP, it becomes a pad eater.
Obviously increases cut, it is like a turbo mode, but a lot more vibration as well, especially sideways vibration.
In mf pad, it generates such a heat that the pad's foam interface melts inside, like b&s black mf pad without center hole.
The Rupes 6in pads on a 5in BP on a 21 becomes convexed, and the center hole opens up like a cone, if you insist in using it. The Velcro durability shortens as well.
Rupes engineers were right when they decided the relation of offset and BP size, spot on.
I'm considering buying a 15 MKII, so I can use 6in pads.
Or buying a Chinese knock off, unfortunately, because a Rupes 15MKII will cost me 1000 bucks .
Best regards

Great post and feedback.

The moral of the story, use the machine as it's manufacturer designed it to be used. Go outside their parameters and be prepared for the potential issues and don't complain to the manufacturer when the changes create said issues.

[Eldorado2k]

1 the main reasons I'm happy I ended up with a Boss G21.