Progress on copper laps

[pmace]

I use Lindsay templates for sharpening by hand. I've been using copper practice plates for laps for a while now with excellent results. I've tried lubricants of all types (silicone oil, WD-40, mineral spirits, alcohol, Windex) and have come to the conclusion that dry is the best. I have one lap with 1200 grit, one with 3000 and the last with 50,000. If the tip is chipped 1200 takes the face down in about a minute and polishing with the other two is 20-30 seconds each. When they get dirty just wipe them off and add more powder by spreading it with your finger. Powder is cheap from Kingsley North.
Using a charging roller to charge a plate with 600 grit I can do some minor re-shaping. Major work still needs the grinder with a diamond disk.

 

[monk]

back in the dark ages, i even used plastic cd disks that were giveaways. they were better than nothing. i used tungsten carbide grit on them.

 

[rweigel]

Initially I was using diamond paste only for polishing. But after some encouraging reading here and at the faceter‘s guild I bought coarser diamond preparations and shape HSS gravers with 40 micrometer grit. Copper laps for shaping and prepolishing grits, hard brass for final polishing with 0.5 micrometer AND heel forming. That works slow enough to get very good control over the heel width. The laps are only 5cm / 2“ in diameter and very affordable (machine shop supply, copper and brass blanks). I‘ve not seen any drawbacks from using those small laps. The most left „lap“ is a diamond separation wheel.

 

[pmace]

I’ve started using denatured alcohol as a carrier. It lets you spread the powder out thinly and evenly and dries in a few seconds. I use much less powder this way. I’m amazed at the mirror finish you can get by hand. I’ve got some 14000 grit coming to help speed the process along. Going from 5000 to 50000 is quite a jump and it takes a little while to get that mirror polish. Seems to work better than electroplated “stones”.

 

[papart1]

sounds interesting..........2" dia., right?

 

[pmace]

How often do you clean your laps? I'm wondering if letting the diamond build up a little bit would improve performance. On the coarser grits there would obviously be more swarf buildup that would require removal but the finer grits should handle it better.

 

[rweigel]

sounds interesting..........2" dia., right?

Yes, 5cm is almost 2“ (5.08cm). The discs are 2mm thick (0.08“), punched out of sheet, roughly 2 $ per disc. As they are punched out, they are slightly domed upon arrival, it tooks some work to flatten them.

This litte machine I made over easter. It works very satisfying for me. I‘ve just grund high speed steel with it, no carbide yet. It takes up very little space compared with the XYZhones marketed.

 

[rweigel]

How often do you clean your laps? I'm wondering if letting the diamond build up a little bit would improve performance. On the coarser grits there would obviously be more swarf buildup that would require removal but the finer grits should handle it better.

With mine, I wipe them clean with degreaser once they are slow down in cuttings speed or leave scratches in the polished face and heel. In case of the polishing wheel with 0.5um diamond paste it might be steel debris buildup that causes the scratches. One day the brass disc should be charged with diamond to such an amount that it still polishes after wiping. As I done not engrave on a daily bases, I could not give you a frequency for cleaning and (very slight) recharging.
Important: if you wipe the graver clean for inspection during sharpening, do NOT USE the same rag for all diamond grits. Cross-contamination could happen fast, causing scratches in otherwise polished faces.

 

[papart1]

Thank you sir for clarification. Rob