Scraping Scratches

I am a new scraper but I have been at a bit. My Biax is developing the scratches in the pictures. They appear on the return stroke as well as the forward stroke of the scrape. Carbide blades sharpened with 3000 grit diamond. This is driving me crazy and didn't occur on previous project. Any ideas as to what is causing this? Thanks.

Without having a description on how you are scraping or a video, I would guess that you are holding the Biax too low or having the work piece too high. That leads to the carbide tool having too low of an angle and you are actually cutting on the bottom of the blade (making a big, blunt, positive rake cutting angle that leads to chatter, the bad 'N" pattern and lack of scraping depth). I normally hold the Biax horizontal to the floor (i.e. in the same plane as the floor) when roughing because the Biax has the proper angle for the blade built into the machine. I'm not talking about the 5 degree negative rake on the carbide insert. I'm meaning the blade that attaches into the biax and holds the carbide insert. Does that make sense?

Do you get the same scratches when you hand scrape? When I look closely, I see the same two-line scratches in your scrapes as well.

*** Disclaimer *** -- I am no expert and others on this forum know a heck of a lot more than me.

pbanderson said:

I am a new scraper but I have been at a bit. My Biax is developing the scratches in the pictures. They appear on the return stroke as well as the forward stroke of the scrape. Carbide blades sharpened with 3000 grit diamond. This is driving me crazy and didn't occur on previous project. Any ideas as to what is causing this? Thanks.

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I don' know nutting, but can you confirm what metal was scraped in the "previous project" and what it is you are working with this time?

It looks as if Bill has been giving you scraping lessons. You must not be sharpening your blade on a power lapper like a Glendo or a Baldor type Grinder with a tilt table. It looks like you hand lapping them on a 3000 grit hand lap. You will never get good results with it. Also it appears you are scraping steel. It is almost impossible to not get scratches. I see your in DC. If you have a free Saturday you should arrange to meet Dee - or Palo 2 of our members who live near DC and volunteer scrape at Tuckahoe Steam & Gas Association - Machine Tool Museum
I am sure either would show you how to sharpen your blade or scrape by hand and a BIAX scraper. I will ask them to come one here as they are both expert scrapers. You have to be careful on here who you listen too as a few people have no clue IMHO. As you can see I am the USA and EUROPEAN BIAX Scraper Instructor. Several members here are my students who know how because they have done it. You can Google my name and put BIAX next to my name and see I TEACH how too in person.

The edge on your blade does not look very good from the pics.

Richard King said:

It looks as if Bill has been giving you scraping lessons.

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Your eyes are getting old, Rich, if you think that looks like Blanchard ground!

Too lazy to bother to scrape that sort of item, Iyam.

pbanderson said:

I am a new scraper but I have been at a bit. My Biax is developing the scratches in the pictures. They appear on the return stroke as well as the forward stroke of the scrape. Carbide blades sharpened with 3000 grit diamond. This is driving me crazy and didn't occur on previous project. Any ideas as to what is causing this? Thanks.

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Guy goes to the urologist with a complaint. So the doc says: "Let's take a look at it, get this gown on, and begin". Guy goes behind the divider, starts changing, looks out from behind the divider, and asks for a hanger, doc finds a hanger hands him the hanger, A few seconds later he asks for comb, doc says he does not have a comb, some time passes he asks for a lint brush, doc is a bit annoyed and tells him does not have one, a few seconds later gay ask the doc if there is a place where he can hang his clothes, doc is a bit irritated now, but keeps his cool, tells him to hang it on the divider....

This point the guy comes out sits down on the examining table and the doc collects his cool.

"So please describe your problem". The guy, "I rather show it and see if you can see it" He opens his gown and stands in from of the doc. Doc is looking at it and says: " I see nothing wrong" The guy insists that he looks again and insists that the problem is right there and very visible. The Doc stars at the guy's privates and says: "Nope it all looks normal to me, but indulge me and describe the "problem"". To which the guy: "Well I am disappointed that you do not see it, but it is most obvious that the left one is quite a bit lower than the right one". At this point, the doc is in disbelief, but being a cool professional, explains that it is normal, everybody is like that, and so on, but just out of curiosity he asks: "Why do you think it is a problem?"

"Well doc you see, I do not know how you can live with such an untidy mess."

Besides the joke, you are being a bit hard on yourself . I think you are pressing down too hard so the Biax does not have time to lift the blade from the surface, and I think you also have the rake on the blade wrong, it looks like chatter on the forward stroke, but it might be just a bad photo. Run your nail over the edge of your blade, if it catches at all you have smal nicks. Please describe why you think the return scratches are a problem?

dee
;-D

Richard King said:

It looks as if Bill has been giving you scraping lessons.

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thermite said:

Your eyes are getting old, Rich, if you think that looks like Blanchard ground!

Too lazy to bother to scrape that sort of item, Iyam.

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Are you two going camping? This place is no place for a fight . I say nuttin', but I saw Rich's scraping, Bill still owes pictures or sumptin' . A friendly banter is cool, but we have all seen these things deteriorate reeeealy quick.

Peace, I am out.


dee
;-D

How Dee, so informative. Thought you were going to pass him some wire too, you know the kind ranchers use...You remember right...lol You must be afraid to say something....lol...

Pic L to R: Here is Dee's Biax Scraping on a surface plate. MIT Professor Power Scraping, Yours Truly Scraping Straight-edge, German students scraping cast iron plate and Steel hold down.

Bill,
Nowhere in Richard’s post I see mentioned Blanchard grinding.
I think that you hit the nail on the head on your first post. Similarly to Dee, I’d plee both you and Richard to leave your personal disagreements away from this thread.


True that the color balance, the light, and the surface finish could play some tricks. However, I did have as well the suspect that it is a surface-ground piece of steel.
The shape of the scraping marks corroborates such impression and, possibly, hint to relatively high surface hardness (or very bad blade sharpening job).
I concur with Richard, Dee and others that the troubleshooting should start from the sharpening of the blade. I remember at the scraping class that Matt, one of the students, had scratching issues with his brand-new Sandvik blade and it turned out that there were a couple of tiny chips on the cutting edge.
The top and bottom faces of the blade are as important, if not more important, than the front face and need to be polished to a mirror finish.
I don’t know if pbanderson has a proper grinder or is sharpening his bladed with a hand lap. In both cases it is of paramount importance to keep the angle constant. Even without a proper grinder/lapper, you can create a fixture consisting of a flat surface held at 95° against the edge of the lap, so that you can rest on it the blade while lapping it.


Paolo

dcsipo said:

Are you two going camping? This place is no place for a fight . I say nuttin', but I saw Rich's scraping, Bill still owes pictures or sumptin' . A friendly banter is cool, but we have all seen these things deteriorate reeeealy quick.

Peace, I am out.


dee
;-D

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Only when he's off his meds. Rich has been doing really well of late.

I don't mean to trifle with him - just share a good natured giggle over his mini-bitch-slap.

But s'truth - I also don't see a lot of point in Biaxing steel plate when Blanchard services go cheaply enough.

Need flaked afterwards? Pass. How would anyone know? We don't yet know the intended end-use.

Oh.. the pictures thing? That's a side deal. Only after I have confirmed obit of Phil F. AKA "machtool". He simply pissed me off to where I decided "not during his LIFETIME". Not as if it had any effect on my paycheck, after all. I'm retired.

And I hope he lives forever, too. BTW. Or at least longer than I do. Phil's a good egg. Just thinks he is harder-headed than I am. It ain't so.

My first look at his picture, made me think he is using a Biax Flaker.

I have a old Biax blue and never had this to happen to me.

What do I know? Is there a AA for scraper fans?

Ken

4GSR said:

What do I know? Is there a AA for scraper fans?

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Nah. It doesn't seem to be at all like a booze addiction.

The way Rich describes loving to scrape it seems more like a slow building orgasm of satisfaction that you want to keep pushing to the next level, lower error, more points, more lovely pattern...

And yet.. the feet hurt, the back hurts, the muscles are stiff, the eyes weary and all that at day's end?

Welll... I do recall some wimmin that would kinda wear yah out, but you didn't ever want to COMPLAIN about that, so maybe he's explained it perfectly, after all?

Richard King said:

It looks as if Bill has been giving you scraping lessons. You must not be sharpening your blade on a power lapper like a Glendo or a Baldor type Grinder with a tilt table. It looks like you hand lapping them on a 3000 grit hand lap. You will never get good results with it. Also it appears you are scraping steel. It is almost impossible to not get scratches. I see your in DC. If you have a free Saturday you should arrange to meet Dee - or Palo 2 of our members who live near DC and volunteer scrape at Tuckahoe Steam & Gas Association - Machine Tool Museum
I am sure either would show you how to sharpen your blade or scrape by hand and a BIAX scraper. I will ask them to come one here as they are both expert scrapers. You have to be careful on here who you listen too as a few people have no clue IMHO. As you can see I am the USA and EUROPEAN BIAX Scraper Instructor. Several members here are my students who know how because they have done it. You can Google my name and put BIAX next to my name and see I TEACH how too in person.

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First thank you guys for taking time to respond.... :-)

My teacher... not Bill, rather bits and pieces from Practical Machinist posts, Connelly and Morgan books, Keith Rucker, Stefan Gotteswinter among others on you tube. At least 8 times through Richard's video and some practice.

Thanks for the referrals but I live in Seattle, WA not DC. I would love to have some experienced scrapers close by I could talk with. Also interested in your (or others) class Richard. Hopefully a bit closer to home.

I tried lapping sides with DMT diamond plates 600 to 1200 but result was unsatisfactory. Ended up using Baldor for sides as well as fronts. Baldor has 3000 grit lapidary plate, reduced in speed to about 300 rpm with VFD. WD-40 as lubricant, 5 degree negative rake on edge. Can't see chips with loop or feel any on edge with fingernail. Steel part of the blade is rough ground but working portion of carbide looks good to me. Although you can see a slight secondary bevel at the edge of the blade, it was made by the 3000 grit and only a small fractional degree steeper.

Material: first piece that seemed to work better, a cast iron Record plane(English). Material I am having the scratches on is new Lie Neilson (premium US manfg) plane that they characterize as Ductile or Nodular iron.

The scratches look like s--t and speak of lack of technique.

Holding scraper, ELM-7 variable speed, like the professor in #9, arms close, scraper level, conscious of moving feet and using body, alternating 90 degrees each pass. What's up with the chatter I am getting? Stroke in the pic is about 5/16 to 3/8 inch. Note I had Ed Dyjak go through the scraper and its in good shape.

Looks like you're trying to scrape a very hard material. What is it exactly?

Paolo_MD said:

Bill,
Nowhere in Richard’s post I see mentioned Blanchard grinding.

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I've no klew why you would have expected there to be?

Blanchard grinding is an affordable and right USEFUL technique when you have rolled steel plate of undeterminate surface condition instead of reasonably predictable Cast Iron. OP did say he HAD been doing just fine WITH Cast Iron.

What changed, then?

The OP has not specified - despite hints that it would be information germane to his issues - what material he is working on, nor its condition prior to beginning his scraping, nor what his goals for it might be.

Those are not "personal" issues in any way, and I'd appreciate it if you would kindly refrain from stirring an empty pot to create such.

They are technical data points, and they have an influence on what he can expect.

If he would be so kind as to share that information, I'll be more than pleased to stand quiet and let Richard explain what he should or should not be doing to get better results with blade, Biax settings, angle - any and all of that he is expert with - even on steel.

Call me lazy, but Blanchard ground and I'm DONE with it. That's all rolled steel plate deserves. It is what it is, and you are seriously optimistic to think it won't move as its surface is further disturbed. Or just out of orneriness.

pbanderson said:

Holding scraper, ELM-7 variable speed, like the professor in #9, arms close, scraper level, conscious of moving feet and using body, alternating 90 degrees each pass. What's up with the chatter I am getting? Stroke in the pic is about 5/16 to 3/8 inch. Note I had Ed Dyjak go through the scraper and its in good shape.

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Without clear answers to a few questions several of us have asked you, I don't see much wrong with scraper and the scraping marks.
The chatter could mean different things depending upon the material.

What kind of metal is it?
Surface hardness (at least in general terms, like very soft/soft-you can file it easily-, medium hard-a file bites to it, but takes off very little material-, or hard-a file tends to skip, without removing (almost) any material)?
How do you sharpen your blades?
How much are you pressing down on the Biax (with the power-scraper off, you could put the piece on a bathroom scale and press down the same as you do while scraping)?

Without details it is practically impossible for us to help you.

Paolo

Chatter often indicates a blunt tool. If you can't scrape a layer off your fingernail with only the weight of the tool pushing it down or if you can see the corner between the bottom and the end of the tool, it's blunt.

I've had "chatter" like what's pictured before too. If I remember right it was mainly the sharpness/angle of the blade that smoothed it out. Speed can help too. If you can slow your scraper down you can support it better and hold it at the correct angle more easily.

It's not to far different from resolving tool path marks when machining. Think about it like your rigidity, feed, speed, and tool geometry.