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Replacement blades for Biax scraper

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skipd1

Cast Iron
Joined
Jan 6, 2010
Location
Bismarck, ND
I have acquired a Biax power scraper and after finding out the prices of replacement blades I have decided to make some for myself. I want the 150mm length blades and I will braze on carbide blanks and radius them. However I do not know what type of steel they are made of and the thickness and width they should be. Can they be made out of mild steel or does it need to be tool steel. Also I have noted that the 150mm blades are thinner than the short ones I have and thinner than the blades with the indexable insert heads.
Any advise or dimensions would be greatly appreciated.
Thanks

Skipd1
 
It looks like they are just under 20mm wide. I made mine out of mild steel, 1/8" thick.
 
I am a hobby scraper on occasion scraping my own machines, and much favor the clamp type holder. With it I can sharpen both sides, or potentially 4 sides (8 edges, top and bottom of 4 edges), and the only time lost while scraping is when I unclamp and move to the next edge. Alternatively one could have different radii on different edges and change as needed.

They say a hand push type scraper should be springy, at least slightly, though I've never noticed any spring in my Anderson scrapers, or maybe I just don't apply enough pressure so as to cause it.
 
I got two hand scrapers that Forrest Addy made from 1018 CRS shanks and brazed-on carbide blanks. Richard King saw them a couple of years later, and suggested I thin the shanks so they would be springier. I did one overnight (CRS bowed like a banana, but simple matter to bend back straight) and was able to compare stiff and flexible of otherwise identical scrapers the next day of the workshop.

Result: flexible is good. You can overdo it, and there may be heavy removal cuts where you want a stiffer blade. But generally, flexible blade shanks are good.
 
I guess where I was going with the flexible blade thing is that all else being equal a quenched 35-80 point carbon bearing alloy with 40-45 RC temper will be a true spring which will not take a set, even if it were made too thin, a mild steel one will take a set as soon as it reaches past it's elastic limit.
HT to spring temper and it can't get past it's elastic limit in normal use.
 
I didn't realize that I posted this in the South Bend Form as well, There are some great comments there as well. As I stated there, I plan to try making some with mild steel and some tool steel as well. Yes I found the Dapra prices for the replacement blades a little scary as well.
Thanks everyone for the comments and advice.

Skipd1
 
I am also somewhat confused to the different radius of the blades and their widths. What radius is best for roughing and what size for finishing and scraping out to higher point/inch? Is the 30mm radius for finishing and the larger radius for roughing?
 
sfriedberg's last link has what you want. 3/32 x 5/16 x 2, cut length as desired. The 1/16 would work, but I'd like them longer than 1/4".

The bigger radius is better for roughing, but it still must match your job. South Bend makes me think of relatively small surfaces. Large radius cutters are more difficult to predict the exact point of contact and tend to dig corners more easily, especially when you try scraping out of position, such as positive lathe ways and dovetails.
 
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