Biax not cutting smooth

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Lucas E

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I am new to scraping and just got a biax 7 ELM. My scrap marks are not looking as smooth as I feel they should and I need some help diagnosing the problem. I'm running a 6" insert type blade with a sandvik scraping insert ground at 60 mm radius with a 5° negative take. Are the blades not polished to a high enough grit? Too slow a speed? Not enough force? Any help would be appreciated. I'd love to take the Richard king course however not sure when the next one close to Oklahoma will be.

This was just a strip I ran across the table to show what I'm seeing in my cast iron parts
PXL-20210324-180924710.jpg
 
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60 degree? Where? A picture close up of the insert would be helpful, generally, the insert should have a radius on it's cutting face, with the corners rounded off somewhat to avoid digging the corners in and scratching. The surface should be machined off before scraping. The non insert type (brazed on) cutters work more smoothly due to the greater flexibility of the shanks, and the inserts should be finely polished/ground. Speed, indeed does make a difference, also stroke length.
 
Something to give scale to the scrape marks would be helpful.
 
Are you sure that material you are scraping is not steel? Also, you should be scraping with the radiused sides of the insert, not the flat sides.
 
All 4 sides are radiused at 60 mm. The table showing the marks is steel, but I just used that to take a nice picture. I'm seeing the same design in cast iron as well.
 
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The cutters used on steel are HSS and are ground differently. I do not understand about the 60 degrees, Biax cutters are ground to a specific radius, measured on millimeters, the ones that I use for cast iron are 60 mm radius with the 5 deg. negative grind, the cutters for steel that I have in my blade kit are HSS with a 60 degree SINGLE FACETED cut and also 60 mm radius. The old man who bought my scraper and flaker bought all the blade kits with brazed and insert holders, spent a LOT of money, buying new about 15 years ago, when he passed, his sons gave them to me in appreciation of my tolerating his ways --- I have never tried to scrape steel, but obviously, it would seem that the regular carbide blades for iron and not appropriate for steel. The inserts for iron are ground on only two opposite sides when new, if they are ground on all sides, I can't see how they would be stable in the holder and would tend to move around in use.
 
benmychree said:
The cutters used on steel are HSS and are ground differently. I do not understand about the 60 degrees, Biax cutters are ground to a specific radius, measured on millimeters, the ones that I use for cast iron are 60 mm radius with the 5 deg. negative grind, the cutters for steel that I have in my blade kit are HSS with a 60 degree SINGLE FACETED cut and also 60 mm radius. The old man who bought my scraper and flaker bought all the blade kits with brazed and insert holders, spent a LOT of money, buying new about 15 years ago, when he passed, his sons gave them to me in appreciation of my tolerating his ways --- I have never tried to scrape steel, but obviously, it would seem that the regular carbide blades for iron and not appropriate for steel. The inserts for iron are ground on only two opposite sides when new, if they are ground on all sides, I can't see how they would be stable in the holder and would tend to move around in use.
Click to expand...
I appreciate the help, however I don't think you are understanding correctly. I am indeed trying to scrape cast iron with a carbide blade that is ground to a 60 mm radius and has a 5 degree negative rake. I am getting what looks like chatter marks in every cut, like it's not taking a smooth cut. I simply ran it across my steel table to get a picture of the chatter marks to show what I'm seeing in the cast iron.

My mistake. Yes, 60mm radius
 
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Also, the angle that you hold the scraper to the work can effect the scraping action. I have never seen a chatter pattern like that, has the cast iron been machined prior to being scraped? approximately what angle are you holding the scraper?
 
Just wondering if there is excessive slop in the slide mechanism.
 
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