LHR21 Backing Plate Screw, RUPES 9.715

The RUPES 9.715 is the LHR21 backing plate screw: a zinc-plated M8 socket head cap screw with its washer already under the head, driven through the center of the plate into the polisher's drive. One screw holds the whole plate. RUPES lists it on the LHR21ES polisher and the LHR21 Mark III, both of which take the RUPES LHR21 6" backing plate, and on the LHR15ES and LHR15 Mark III with their 5-inch plate. The same part holds the 150 mm and 125 mm pads on RUPES's Skorpio III pneumatic sanders.

Other RUPES machines use different hardware. The LK900E gear-driven polisher holds its plate with six 9.614 Phillips backing plate screws and washers, and the LH19E rotary's plate threads straight onto the spindle. RUPES supplies an Allen wrench with the LHR21ES and LHR15ES for this screw, so a lost or stripped 9.715 is the only part a plate change can't do without.

What Makes it Great:

🔩 Zinc-Plated M8 Socket Head: The plating stands up to the water and compound that collect at the center of the plate, and the hex socket takes the Allen wrench that ships with the polisher.

🧷 Washer Already Fitted: The washer comes on the screw, so the replacement arrives as the complete fastener RUPES specifies, not a loose screw and washer to match up.

🔁 Six Machines, One Spare: The LHR21ES, LHR15ES, both Mark III models, and the Skorpio III sanders share this part, so a shop running several of them keeps one screw in the drawer.

🛠️ Keeps the Polisher Working: Without its center screw a BigFoot polisher has no way to hold a plate, so a spare on hand turns a lost screw into a two-minute fix.

Frequently Asked Questions

How do you change the backing plate on a RUPES LHR21ES?

Unplug the polisher and loosen the center screw with the Allen wrench RUPES supplies with the tool. Lift the old plate off, set the new one on and turn it slightly until it drops into position, then tighten the screw with the same wrench.

Which RUPES backing plate screw do I need?

The LHR21ES, LHR15ES, both Mark III models, and the Skorpio III take this single 9.715. The LK900E takes six 9.614 Phillips screws with washers, and the LH19E's plate threads on with no screw.

What size is the RUPES 9.715 screw?

It is an M8 socket head cap screw with a washer under the head, listed at 8 mm x 16 mm. Use the RUPES part rather than a generic M8, since RUPES's manuals call for original parts on its tools.

Is the Skorpio III plate screw the same as the LHR21 screw?

Yes. RUPES's parts diagrams show the 9.715 holding the pads on the Skorpio III pneumatic sanders (RH353, RH356, RH359, RH323, RH326, and RH329) and the plates on the LHR21 and LHR15 polishers.