How to Match a Back-Up Pad to Your Silicon Carbide Belts
By Supergrit Abrasives | Published: 2026-10-16
Category: How-to Guides
Match a back-up pad to your sander and discs by checking arbor thread, dust hole pattern, and attachment style before buying. Covers hook-and-loop and PSA pad choices.
Quick answer
Match a back-up pad to your sander and discs by confirming three things: the arbor thread (for example 5/16 - 24), the dust hole pattern (8 holes), and the attachment style (hook-and-loop or PSA). For a 5-inch, 8-hole hook-and-loop setup, the J70595H8 back-up pad is a direct fit; for Makita or Ryobi tools with 4 screw holes, use a PSA pad that matches that pattern. Get one of the three wrong and the pad will wobble, clog, or refuse to mount.
Start with the arbor thread, not the disc
The arbor thread is the single most common reason a new back-up pad will not mount. A pad with a 5/16 - 24 thread will not fit a sander with a different spindle, no matter how well the diameter and holes line up. Before you shop, check your sander's spindle or the old pad's thread and write it down.
If you are replacing a worn pad, the old pad's thread is your reference. If you are setting up a new sander, verify the thread in the tool manual or by test-fitting a known pad. Buying a pad with the wrong thread is the most expensive mistake because it cannot be corrected with adapters in most cases.
Confirm the hole pattern and diameter together
Diameter and hole pattern are a matched set. A 5-inch pad with 8 holes aligns with a 5-inch, 8-hole sander and 5-inch, 8-hole discs. If your tool has 4 screw holes in addition to the 8-hole dust pattern, a standard 8-hole pad may not mount securely.
Check the dust extraction path as well. The holes must line up with the sander's shroud or vacuum port. Misaligned holes reduce dust capture and let debris build up under the disc, which shortens abrasive life and can leave swirl marks.
Choose hook-and-loop or PSA based on how you work
Hook-and-loop (H&L) pads let you swap discs quickly and reuse them if the backing stays clean. PSA pads use pressure-sensitive adhesive and hold the disc flatter, which some users prefer for fine finishing, but the disc is not reusable once removed.
For a 5-inch, 8-hole H&L setup, a pad like the J70595H8 pairs with H&L discs such as the Indasa white discs. For Makita or Ryobi tools with 4 screw holes, a PSA pad designed for that pattern is the correct match. Do not mix H&L discs on a PSA pad or vice versa; the attachment systems are not interchangeable.
Check the pad's condition before blaming the discs
A worn or glazed back-up pad can cause discs to slip, fly off, or cut unevenly. Inspect the pad face for embedded debris, flattened hooks, or adhesive residue. If the pad face is damaged, replace the pad before you change abrasives.
Also check the pad's edge for rounding or cracking. A pad that no longer sits flat will transfer that shape to your work, and no disc will fix it.
Step-by-step: match your back-up pad
- Identify your sander's arbor thread: Check the old pad or tool manual for the thread size, such as 5/16 - 24. Write it down before shopping. Common mistake: assuming all 5-inch pads share the same thread. Thread mismatch is the top reason a pad will not mount.
- Measure the pad diameter and count the dust holes: Confirm your sander and discs are the same diameter and hole count, for example 5 inch with 8 holes. Check that the holes align with the dust port. Checkpoint: if the holes do not line up with the shroud, dust extraction and finish quality will suffer.
- Note any extra mounting holes: Some Makita and Ryobi tools use 4 screw holes in addition to the 8-hole dust pattern. If yours does, choose a pad made for that configuration. Common mistake: buying a standard 8-hole pad for a 4-screw-hole tool, which can leave the pad loose.
- Decide between hook-and-loop and PSA: Pick H&L if you swap discs often and want to reuse them. Pick PSA if you want a flatter hold for finishing and do not need to reuse discs. Checkpoint: your discs and pad must use the same attachment system. H&L discs will not stick to a PSA pad.
- Inspect the new pad's face and edges before installing: Look for flatness, clean hooks or clean adhesive surface, and no cracks or rounding at the edge. Next step: install the pad, mount a disc, and run the sander briefly at low speed to confirm it spins true before you start sanding.
Product facts that affect your match
- 5" 8 HOLE, 5/16 - 24 THREAD BACK UP PAD (J70595H8) USA H&L: 5 inch diameter, 8 hole configuration, 5/16 - 24 thread, USA H&L style back up pad, identified by code J70595H8. This is a direct fit for 5-inch, 8-hole hook-and-loop sanders with a 5/16 - 24 spindle, so you can replace a worn pad without changing your discs or tool.
- 5" 8 HOLE MAKITA/RYOBI (4 SCREW HOLES) PSA: 5-inch PSA disc designed for Makita and Ryobi tools with an 8-hole pattern and 4 screw holes, using pressure-sensitive adhesive backing. If your Makita or Ryobi sander has 4 screw holes, this matches that mounting pattern and attachment style; a standard 8-hole H&L pad would not be the right fit.
- 5" 8 HOLE H&L INDASA WHITE DISCS: 5 inch, 8 hole hook-and-loop abrasive discs in a white appearance, available in grits 36 through 600, sold in packs of 50. These are the H&L discs that pair with a 5-inch, 8-hole H&L back-up pad, and the grit range covers coarse stock removal through fine finishing.
