# Biax not cutting smooth



## Lucas E (Mar 24, 2021)

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


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## benmychree (Mar 24, 2021)

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.


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## benmychree (Mar 24, 2021)

Something to give scale to the scrape marks would be helpful.


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## Lucas E (Mar 24, 2021)

benmychree said:


> Something to give scale to the scrape marks would be helpful.



Here are some more pics. Seems like the blade is chattering across the surface instead of taking a smooth cut.


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## benmychree (Mar 24, 2021)

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.


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## Lucas E (Mar 24, 2021)

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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## benmychree (Mar 24, 2021)

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.


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## Lucas E (Mar 24, 2021)

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.


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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## benmychree (Mar 24, 2021)

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?


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## benmychree (Mar 24, 2021)

Just wondering if there is excessive slop in the slide mechanism.


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## Lucas E (Mar 24, 2021)

It doesn't seem like there is excessive slop. How tight should the guides be set against the wear bars? 

I've tried all angles and can't seem to get it to go away so I don't think that's the problem.


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## benmychree (Mar 24, 2021)

I will look at mine and get back to you on the clearance, I wrote a PM to Rich King and asked him for input.


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## Lucas E (Mar 24, 2021)

benmychree said:


> I will look at mine and get back to you on the clearance, I wrote a PM to Rich King and asked him for input.


There does sleep to be some clearance on mine. If there's supposed to be absolutely no clearance, or ability to rock them side to side then maybe mine are worn past their life. I tried to adjust the screws down tighter however none of the clearance was taken up and I was at the point of stripping out the little slot head set screw.


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## benmychree (Mar 24, 2021)

I can get a .0025 feeler under one side of the slide, and there is no discernable side play, this scraper has not seen a whole lot of use, so the info is pretty much baseline.


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## Lucas E (Mar 24, 2021)

benmychree said:


> I can get a .0025 feeler under one side of the slide, and there is no discernable side play, this scraper has not seen a whole lot of use, so the info is pretty much baseline.


I pulled out the feeler gauges and it looks like I can tighten them down to where I can't fit the .0016 feeler gauge. So i'm guessing my clearances are ok. The machine looks to be in great shape, and my first thought was not that I have a problem with the machine. Possibly the blade/cutter setup...


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## benmychree (Mar 24, 2021)

That may be why Rich reccomends using the thin shanked brazed carbide tools.


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## benmychree (Mar 24, 2021)

I am not sure as to what direction the scraping is being done in, as the rows of scrape marks do not continue from left to right in long rows as would normally be done, all across a surface, and then crossed at 90 degrees, the individual scrape marks should be perhaps 3/16 wide and 1/2 - 3/4" long and have a small width of unscraped surface between each scrape mark.  Are the chatter marks 90 degrees to the length of the scrape mark?


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## Lucas E (Mar 24, 2021)

This is the direction they are occuring. As if I were moving the blade left to right.



post images


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## benmychree (Mar 24, 2021)

That is an awfully short stroke, try lengthening it to about 1/2 - 3/4" and see what happens and play around with the stroke speed.


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## extropic (Mar 24, 2021)

Compared to the blade, the "scrapes" are quite small. Along with lengthening the stroke (for roughing), try adding down pressure. My guess is that the cutter is "skipping" along the stroke and not digging in. I think that is what RK calls chicken scratching.


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## Lucas E (Mar 24, 2021)

Half inch stroke on the bottom. 3/4 on top. Honestly at 3/4" stroke it feels super unwieldy. Like a jackhammer pushing the tip all over the place. I mostly do smaller work, and it seems hard to imagine that would be useful for precise work. But I'm new to this so I dunno.



post images


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## Lucas E (Mar 24, 2021)

Its the machine, or the blade holder cause I can take the carbide blade out and put it in my hand scraper and do this. Do I need to thin the blade holder? This blade holder is 3/16 mild steel 3/4" wide and a little under 6" long. Are dapra blades spring steel or mild steel?



post images


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## eeler1 (Mar 24, 2021)

it’s called chatter.  First thing, sharpen your tool.


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## eeler1 (Mar 25, 2021)

And 2nd thing, sometimes your tool gets magnetized and attracts little pieces of cast iron that cause marks like that.  So, de-magnetize your tool from time to time.  

Sharpen, demagnetize, that's all I got.


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