Todays Project - What did you do today?

[Highpower]

Today was "build a lapping machine day".

A couple of chunks of wood, a cheap 1/4 hp eBay motor, a slug of cast iron round stock, a few electrical bits, a leftover piece of DIN slotted rail and a bit of drill rod. Wallah!



The top of the wood block "tool rest" is cut at a -5° angle to provide a 85° cutting edge for a carbide hand scraper blade. The slotted rail "tool guide" is used to provide the arc needed for the radius on the front of the cutting blade. The short piece of drill rod serves as the pivot point on the guide. I just put a couple of fusion tack welds on them to hold them together.

With the pin in the farthest hole from the lapping disc on the tool rest, it is used with the "long" end of the guide facing the lap surface. This gives a 90mm radius for "rough" scraping. Turning the guide around and using the "short" end of the rail facing the lap, putting the pin in the closest hole on the tool rest gives a 60mm radius for "finish" scraping.

At least that is what I have learned so far...

Now I need to make a similar guide to fit on my pedestal carbide grinder in order to do the initial shaping of the scraper tip before I can lap it. The new blades are supplied with flat 90° surfaces. And I suck at hand grinding radius's......