[GrizHFMinimill] Re: Scraping adventure Group please read announcement [3 Attachments]

[Attachment(s) from mark.kimball2@frontier.com [GrizHFMinimill] included below]

Per Barry's suggestion here are some images showing my low-speed scraper-sharpening setup. Photo #1 shows a 6" lapping disk that's been loaded with 14,000 grit diamond (the other side is a 150-grit plated-diamond surface). Also shows a disposable aluminum bread pan with water in it. The plated-diamond disks dip into the pan to lubricate it while I'm grinding/lapping carbide. I ran the 14,000 lapping plate dry. One of my scrapers is shown below the holder & both are sitting on top of the tool support. The support table is tilted at about 8 degrees to produce a cutting edge that has a 98 degree included angle.

The scraper has a pretty short handle so I probably will make an extender to make it less fatiguing to use.

I turned the arbor for the diamond disks on my 7X12 mini lathe. The disks were purchased from a lapidary supply place on the web, for pretty cheap compared to a real diamond grinding wheel. I got 150, 320, 600, 1200 and 3000 grit disks, and some 14,000 grit diamond powder. I made a charging roller out of a 1/2" bearing & that seemed to work OK. BTW, starting with the 600 grit worked OK so I didn't need the coarser ones (for this job anyway).

#2 is a closeup of the tool post and tool holder. The steel pieces on the holder are used to clamp the scraper in place -- one of them has an allen screw on the side to push the scraper against the other steel piece. The left side of the holder has a brass insert attached to it. The insert has a radius (I used a compass to scribe an arc, then filed the insert down to match the arc). The tool support has a little fence on its end and the brass insert is pushed up against it so the scraper describes an arc as I grind it. This approach gave me a very nicely radiused scraper, and I can use inserts with any radius I please (within reason anyway).

#3 is a photo showing my low speed "motor". It is a stepper motor, stepper driver and a hand-wired oscillator circuit made with a 555 timer. I could've replaced the 555 with a microcontroller but that seemed like overkill -- although then I could claim I have the start of a CNC sharpening tool!

Next time I do this kind of description + files deal I'll put them all into a PDF. Seems it would be a lot cleaner that way.

Mark

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