Lapping tips

Just before I packed up my workshop back in mid-2022 I’d been using my laps a lot and made some notes on several things I’d noticed at that time:

• if the laps were rotated at 1000 rpm instead of my more usual 1500, the Wet & Dry (W&D) paper lasted twice as long as usual and I could get a lot more work completed with each sheet, which at about $2.50 a pop made good sense to me.  See Figure 1 below
• I pressed very lightly on the W&D paper

​Figure 1 - I know it looks like a jellyfish, but it is actually a sheet of very well worn 600 grit W&D paper!

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• be very, very careful when approaching the lap with your work piece and apply it squarely to avoid that annoying rounded bevel to one corner or edge
• I came across a beautiful piece of Marsden (Flower jade) which had an interesting texture of coarse crystals of nephrite (one was over a cm long by 0.5 mm wide and I only saw its size once it dropped out!) in a very fine, soft matrix. The polished texture was “orange peel” and try as I might, I could not get a good finish using anything finer than 400 grit paper as the softer matrix undercut so badly. So I left it at 400 and enjoyed the semi-matt finish! Think to yourself – do you need to polish every piece?
• I’d finally worked out, after all these years, how to avoid losing fingernails when grinding thin pieces on the lap – attach a “T” of duct tape to the back and hold that instead. It’s so obvious I wonder why I didn’t think of it 15 years ago? No more ground off fingers – whoopee!!  See Figure 2 below

​Figure 2 - a small piece of duct tape attached to the back of a thin piece of Marsden.  Normally I'd be grinding away my fingernails  on the flats

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• and finally, for a perfectly flat surface you can’t go past a sintered diamond lap. Mine is 500 grit, but it’s not fast.  Just a thought ...!
  
  

It's good to be back!  Happy carving!