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View Full Version : small carbide tipped scraper (video)



Tony
07-02-2014, 01:21 PM
Greets all. Am ramping back up to finish the surface grinder but needed to make
a small scraper for the small dovetails. Decided to take the camera along for the ride.

No rocket science, but I thought you guys might like to see forming the ferrule out of
thin walled tube. I posted about this some time back, but here it is in action.. happens
around the 7:50 mark.

ps before anyone busts my chops for turning wood on a metal lathe -- It hurt me more
than it hurt you -- but sometimes a man's gotta do what a man's gotta do. :p


http://youtu.be/6ZKhqn7TozI

daryl bane
07-02-2014, 05:35 PM
Love it. I was just evaluating my dovetail scraper situation , so this was timely. Also the ferule tutorial was enlightening. Thanks

Forrest Addy
07-03-2014, 08:43 AM
I could fuss over picky details (How many ... to screw in a lightbulb) but basically Tony's video shows how quick and dirty DIY carbide scrapers are made. In the past I've made dozens of scrapers specialised for different things and maybe 300 of a single pattern for my scraping classes. The general procedure is the same shown on the video: a shank with carbide brazed on one end and a handle on the other. Tony shows and explains each step well.

Small dovetails can be pickier to scrape than large. You have to be as careful about scraping into the xcorner, sweating scraping out the relief, being careful about either rolling off the edge or leaving it raised. preserving geometry (squareness and parallelism with other axes); a PITA but it has to be done right and the smaller the scale the pickier the task.

I liked Tony's remarks on cleanliness. Scraping involves very dirty operations (the actual scraping) immediately followed by very clean operations (printing the surface from your blued references). Swarf carry-over is always a hazard. Here is where a shop vac is your best friend - not compressed air which blows the swarf everywhere but a vac with a crevice nozzle which, assisted with a small paint brush, sucks it up all accessible loose swarf and keeps it safe in the cannister. I keep a shop vac for this very purpose but most any shop vac with a fresh filter will do (fresh filer maxes CFM's) will do.

Another point is to clean up and lap the rough carbide to a mirror finish on both faces before you braze it on the shank. Once brazed, it's hard to address the face because of the shank's interferance. The mirror finish is necessary because a scraping edge is the intersection of two planes. If one plane is rough the edge is rough and you need a dead keen cutting edge for efficient scraping.

I generally use a butt joint to join carbide to the shank. Silver brazing alloy is stronger than mild steel and holds remarkably well. The scraper in the video has carbide with a long overhang. It needs a slot for bedding.

YMMV depending on the work you have to do.

Scrape wisely