Backing for lapping film

[Tony Wilkins]

On a recent Lee Valley order, I tossed a set of the PSA Diamond lapping film 3x6 sheets to try. What is a good backing to attach them to? I’ve read float glass, granite tile, mdf are good choices. Any pros and cons? I’m hesitant to use float glass as I’m likely to drop it lol. So what do y’all think would be the best option for me?

[Andrew Hughes]

Get a small granite plate. They are pretty indestructible and much more likely to be flat. You might even check CL for a used one they are out there in some areas.

[Tom M King]

Mine are on a 9 x 12 granite surface plate, but it doesn't get moved around. It stays on the drainboard of my sharpening sink, and the faucet spout is a double swivel that covers a large area on the drainboard.

Woodcraft has granite surface plates on sale several times a year. I only drag an edge backwards on it. It is fairly fragile, and a sharp edge will go right down through it, even with a guide. Going backwards, it lasts a very long time. I use them under running water.

[Rob Luter]

I mount mine on 3" x 11" pieces of 1/4" glass, in turn mounted on MDF blocks with oak veneer. It makes for a dead flat and stable base.

https://c2.staticflickr.com/2/1488/26712452175_7e480b7af1_b.jpg

[Derek Cohen]

I wrote about these sheets several years ago, having been sent a bunch by Lee Valley for evaluation: http://www.inthewoodshop.com/WoodworkTechniques/DiamondFilm.html

I made up a travel sharpening kit with 15-, 3- and 0.5 micron grits (and optional 0.1 micron) ...

http://www.inthewoodshop.com/WoodworkTechniques/DiamondFilm_html_m397af68d.jpg

The plates were planed hardwood (Jarrah) covered with perspex, and the film on the perspex.

http://www.inthewoodshop.com/WoodworkTechniques/DiamondFilm_html_m1436c049.jpg

With a perspex cover, they travel well.

Regards from Perth

Derek

[glenn bradley]

The finer the grit, the more critical the backing material. I use tile for coarse grits and switch to glass around 15 micron. I also have granite reference plates but, use those generally for truing things. As for dropping glass, mount it to something.

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[Bill McDermott]

I use the 12" square tiles from the borg. Black "granite" is really smooth and flat and so inexpensive you ought to at least try it. I have many grits on tiles that slide in and out of a box. The one in use is on top of the box. I tried using just water, but a light misting of 3M spray glue made life a lot easier. I suspect the glue creates enough variation to offset any precision in the plate anyway. A spray bottle of water and a rag makes this system work well for me. My box has a hinged top with stop blocks on the underside for referencing my honing jig and I protect the topmost tile, which has a ready to go strop.
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First time I smoothed the films to the tiles I would up removing my fingerprints. You can't even feel the sub micron grit. Weird when your finger pads get shiny. :)

[Barney Markunas]

Check the dumpster behind any stone counter fabrication shop. It will likely be full of scrap that is of no use to the shop but might work very well for you. You can probably color code them to help keep your grits straight. I'd ask first but they will likely say "take all you want".

[Rob Luter]

Check the dumpster behind any stone counter fabrication shop. It will likely be full of scrap that is of no use to the shop but might work very well for you. You can probably color code them to help keep your grits straight. I'd ask first but they will likely say "take all you want".

Good call! We were looking at counters last year and the sales gal clued us in to that. The dumpster is full of usable scrap and it’s fair game.