Sanding Discs
Aluminum oxide sanding discs in PSA and hook-and-loop backing, for random orbital and rotary sanders on weld finishing and surface preparation.
PSA or hook-and-loop - decide by how often you change discs
- PSA - pressure-sensitive adhesive, a peel-and-stick disc that bonds directly to a smooth pad. It sits flatter and thinner against the work, which gives better feel on flat panel finishing, and it costs less per disc. It is single-use: once peeled, it does not go back on.
- Hook-and-loop - the Velcro-style backing. More expensive per disc, and worth it the moment you change grits frequently, because a part-worn disc comes off and goes back on. On multi-grit finishing work it pays for itself in discs you did not throw away.
Both need the matching pad. A PSA disc will not hold on a hook-and-loop pad, and the adhesive residue ruins the pad's hooks.
Work the grit sequence, do not skip it
Every skipped grit leaves scratches the next grit cannot remove, and they surface at the end when the part is polished and it is too late. Step through the sequence, and change direction slightly with each grit so you can see when the previous grit's marks are gone.
Finishing a weld on a visible part is mostly patience and sequence, not pressure.
Aluminum oxide and where it stops
Aluminum oxide is the general-purpose grain and it is the correct economics on mild steel, on wood and on paint removal. It is a friable grain - it fractures to expose fresh edges, which is why it cuts consistently as it wears.
On stainless and hard alloys it dulls quickly and then generates heat rather than removing metal, and that heat is what discolours and distorts the part. For sustained stainless work, ceramic grain in a fiber disc or belt is the better buy despite the higher price.
Loading, and how to avoid it
Discs clog with soft material - aluminum, paint, filler - and a loaded disc burnishes instead of cutting. Lower the speed, lighten the pressure and clean the disc rather than pressing harder. On aluminum, expect to change discs more often than the grit rating suggests.
Let the tool find its speed
Excess pressure on a random orbital stops the orbit and turns it into a rotary, which leaves swirl marks you then have to sand out. Guide it and let it move.
Brand range: VSM.
Counter pickup in North York.
