Lapping films
- This topic has 35 replies, 8 voices, and was last updated 11/19/2018 at 2:32 pm by
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In my experience for the PSA lapping films, (pressure sensitive adhesive) are one time, apply them and use/leave them till they’re used out. If you remove them they tend to stretch out and can’t be reapplied. The non PSA may be different. Depending on how you attach them to your platen they may well be removable and used again. Just like Cliff Curry’s You Tube Video portrays.
Here’s another You tube video showing how he uses the non-PSA lapping films.
So if you want to be able to use various grit films on one set of blank platens and change them out as you progress down the grits, you’ll need to use plain lapping films without the pressure sensitive adhesive backing. That is don’t use the peel and stick films. Use a film with no adhesive backing that you have to attach with an adhesive tape or a similar method.
There are many sources to procure lapping films and also several different kinds of lapping films using different abrasive particles. I believe, based on my experience, the diamond lapping films work best. You can purchase sheets you’ll need to cut, yourself, into strips or you can purchase lapping films in pre-cut strips.
Marc
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Jacob, IMO the aluminum oxide and silicon carbide or silicon dioxide lapping films don’t cut or work as easily and efficiently as more expensive diamond lapping films. Also, I don’t think you need to employ a film more coarse grit than 6µ or 9µ. Anything more coarse you should have covered with your WE diamond stones. Also be careful what you’re buying. Many of the films don’t specify what the abrasive medium is in the lapping film sheets. The price may be the give away. DLF sheets are not cheap.
That being said, I do believe those film sheets could be cut into appropriate sized strips and affixed to blank platens with double stick scotch tape, the thin cellophane type. Scotch 3M makes one labeled for posters that you have to peel the backing to expose the second sticky side. They also have one with a yellow plaid label that both sides are sticky and exposed right off the roll , (no backing to be peeled). I prefer this yellow one. This tape is thin and holds well though it can be difficult to handle.
Marc
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I haven’t used non-diamond lapping film, so can’t comment intelligently on its value versus the same film in diamond. There are a number of suppliers out there, but their main market in large quantity industrial polishing of things like fiber-optic lines, so they’re not particularly interested in catering to such a small market as us. Usually, they’ll offer to sell you what you need, but the prices are a bit high. I just bought some 15, 30 and 45 micron PSA film and they charged me $25 per sheet.
This makes the decision a bit harder in comparing diamond to non-diamond abrasive film. Try to work it out in terms of cost per knife. I get at least 20 to 30 knife sharpenings from a pair of diamond films. Cleaning them frequently helps a lot. I use alcohol and a battery-powered scrubber to wash away the metallic schmutz, usually every other knife.
Lee Valley offers 3″ by 6″ sheets of PSA diamond film for $7.10 per sheet. If you’re careful, you can cut four strips from one sheet, or two changes of film. If we assume 20 knives, then one pair will cost you about $0.18 per pair.
Wicked Edge offers their diamond film on 10-strip sheets for $30.00 – five pairs. Assuming twenty knives per pair, the cost will be $0.30 per knife.
The 8.5″ by 11″ film I bought at $25/sheet would produce 22 strips, or 11 pairs. Assuming twenty knives per pair, the cost is $0.11 per knife.
I found a supplier (via Google) that sells 6″ X 6″ sheets of 6-micron film (no PSA) for $5.95 per sheet. You can get eight strips (four pairs) from one sheet, for a cost of about $0.07 per knife. Add to this the cost of double-faced tape and the hassle attached. I don’t know what other grits they offer.
From an overview perspective, whether the cost is 11-cents or 30 cents per knife isn’t enough to fret over. About two sips of coffee at the local diner. That said, keep in mind that the real cost will be $0.30 for each grade of film. If you use 9, 6 and 3.0 micron film on a knife, the cost will be 3 times $0.30, or $0.90 per knife. Less if you get more sharpenings out of each pair of strips.
I cut my film strips with a paper-cutter you can pick up at Walmart or OfficeMax. Works great.
I am not a fanatic about producing an astounding level of mirror finish. As such, I don’t see much need to polish beyond the 3-micron level. Since I have diamond stones to 1500 grit, I don’t need film with grit larger than 6 or 9 micron. If I had the set of handles with 1500 grit on one side and glass on the other side, I’d put 9 micron film on the glass opposite the 1500 grit stone. Then I’d add a set of handles with 6 and 3 micron film. I have an extra set equipped with 1.5 and 1.0 micron film, but hardly ever use them.
All of that having been said, I’d like to make a plug for WE as a source for your film. While the cost may be a bit higher, the films are already pre-cut and you’d be supporting the people who brought us all here.
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