AAAAH, wenn ich die kleinen nadelartigen Stahlsplitter schon seh *pieks* Toll erklärt, war mir garnicht so klar, dass die Kaltverfestigung bei Stahl ein Problem ist. Sieht immernoch nicht aus wie Spaß, scheint aber sehr gut zu funktionieren. Finish sieht sehr gut aus - Manchmal hilfts auch wenn man nich exakt 90° zwischen den Durchgängen versetzt, damit sich einmal eingeschlichene Scharten oder Ratterer nicht aufschaukeln. (Randnotiz, diese Freiflächenfase machen auch die Leute die von Hand mit einem Stichel gravieren, damit sich der Stichel nicht eingräbt.) Übrigens: Probier mal Bronze flachzuschaben, das geht traumhaft (5° Negativ) ;)
Wie immer vielen Dank für deine netten und aufmunternden Kommentare, Stefan. Ist mir auch erst beim Schneiden vom Video aufgefallen, dass ich 90° versetzt habe, was ich normalerweise versuche zu vermeiden. Man verstärkt ja sonst wie du sagst nur die langen Wellen der vorherigen Schabestriche. Sehr spannend, was du von den Gravierern schreibst, davon wusste ich bisher nicht.
@@anengineersfindings Alex, I've seen some wood carving chisels sharpened pretty much like this to avoid digging in too. Thank you for this video -- I had never considered that steel & cast iron would scrape differently, but your explanation makes it very clear!
This is the same kind of geometry used on engraving cutters. The ones used for hand engraving, not machine engraving. Thanks for sharing, I really like the content you have posted so far.
Hi again Alex, I find it somewhat strange, and humbling, that you thank your viewers for their time (as do Stefan & many others I subscribe to). It should be we, the viewers, who thank you. I sincerely thank YOU for your time, effort and the sharing of your expertise on this forum. You teach well and I am grateful. Being in the latter stages of life my passion now runs to classic engineering machinery and the restoration of the same. I am soon to be applying myself to the reincarnation of my new/old "baby" , a G.DuFour 624b Universal Toolroom Mill. It requires quite some degree of refurbishment, and although I will never be able to achieve your level of excellence, I will still enjoy my " love affair" with her. The same passion that you obviously share. Cheers, David (Australia)
Hi David, very nice of you to say that, but I figure no person can achieve a real level of excellence - there are always flaws in man-made things, you just have to look closely enough. Sorry, but I will continue thanking my viewers, :) because life taught me that among the many people I meet face to face, there are only very few who are sensitized or interested enough to appreciate the work or solutions I come up with. Consequently I appreciate it very much, if I can reach out to people with a similar background, interest or passion if you will. All the best for your upcoming reconditioning-job. ;)
Cool info. I scraped both mild steel and stainless steel 304 and didn't really see any of those problems but I was not trying to be so aggressive with the cuts. This is good info to know. It reminds me of the "heel" used on engraving gravers to control depth.
VERY interesting. Scraping mild steel to satisfactory finish and flatness has been a recurring mystery to me since I was an apprentice in 1962. My co-workers and I tried many combinations of edge angle, end radius, topical treatments (olive oil, steric acid, hand cleaner, goops made by the dark of the moon) but nothing worked very well. We got our turbine cases and steam chest covers etc steam tight but every job was a squeaker. That - I'd call it a "heel angle" - reduced clearance angle seems to work slick on steel. I'm on fire to try it. What's frustrating is I use the same trick on my woodworking chisels to control the tool's aggressiveness in cut cut. Engravers closely control the heel angles of their burins and watch maker on the tiny lathe tools they use for clockwork axles. Shoulda seen it but I didn't. Nice piece of problem solving. If I had a medal, I'd pin it on you and feed you a beer and a pizza, if I had beer and pizza. I'm linking this video to Stefan.
Thank you for your very interesting comment, Sir. Very interesting to hear about the techniques you tried to scrape mild steel. Was it the steam turbine housing's parting surfaces that you had to scrape? WOW...! Please let me know about your results with the technique of this video. Thanks for the pizza and the beer - I'll try to get some today to comply with your nice comment :D
This is a great video. Well thought out and very informative. My formal training is as a Carpenter and Cabinetmaker. The geometry you have described is used on hand planes for wood. And the methods are very applicable. Control of how the cutting edge digs into the work piece. Thanks for taking the time to make such a well thought out method of scrapping a material that is common to so many projects. I work as an amateur machinist on projects and I will remember this and apply it in the future for precision work.
I had been looking for this kind of information for days! Great video and great content in your channel, which I have just discovered. Thank you and look forward to watching more of your videos!
Every once in a while, there's one of those "of course" moments. I've been struggling with scraper geometry on steel for ages, lousy surface finish with negative rake, horrible gouging with positive rake, and as you started with your little cardboard diagrams I could suddenly see why, and what was needed. Brilliant. Thank you. I'm out to the workshop, I have a straight edge to refinish.
Thank you very much for your videos! They are very useful. I was able to work cleanly only with a negative angle. The positive angle dug into the metal making steps.
A magnificent video. Detailed, explanatory, demonstrative. Thanks! Surprising, that the end geometry reminds the wooden chisel - worked with sharpened surface down. In the same way, you can control the depth of cut by adjusting the angle with the help of that small "heel" down there. Another idea, again from woodworking. Chip carving knives have to make delicate, curved cuts and are sharpen with convex grinds therefore. Ideally, nowhere they have a flat surface, even near the very edge. Which gives the carver a capability to control the angle and allow the knife to exit material in a very precise and controllable way. May be slightly convex "heel" would help your carbide insert as well?
Excellent work ! I have power scraped steel and , as you mentioned, it works well with the classic 5 degree negative angle. I scraped in a 1100 mm long steel straight edge and then I used it to scrape my 1067 mm Bridgeport X axis. At either end of the table I messed up a little bit, around 3 x 1/100 of a mm, but in between I got a decent 1/100 of a mm over an entire 600 mm length. Thank you for taking time to share your work. Cheers !
Thank You for a very interesting video! Noticed exactly the problems You described. Will try Your geometry. Also liked the little table for the D-bit grinder, I am off to make one of those....
I like that very much. It's shows me the cutting theory with an opened mindset for different materials, and how to adapt to different behaviors. It's creative and down to earth, and it's because of the way you show it. I'm an engineer as well, in electrical power transmission, but i'm passionate about all engineering aspects. Please continue to produce the excellent content, the way you do, with the scientific method, and a distorted guitar riff at the beginning... Cheers from Baie-Comeau Qc.
Thank you very much, Mr. Maltais. Glad if you don't find my videos too "schoolish". And the way I see it, the topic is metal related, so why not a metal audio-intro. ;)
Hi Alex. I just wanted to say that I just found your channel. I like it. Good job on the milling machine rebuild. Thanks for sharing. I'll probably use the info on this video in the future. Keep up the good work. I'll subscribe.
Very interesting. I just found your videos, and like the content and quality very much. I will subscribe and hope for more. I know it is hard work, so I will appreciate and thumbs-up every video. This is GTWR quality!!
Man I've been trying to scrape in a 2m mild steel straight edge using just the positive geometry and what a mess it makes! Thanks for sharing this insight, I'll be regrinding that insert tomorrow!
I thought I had watched all your videos Alex, then found this one. I used to make scrapers from old files when I was a sea going engineer, the grind I eventually settled on was very similar to yours, I had a flat at about 5-10 degrees on the bottom then the top had a shallow 30ish degree angle with the cutting edge at around 45-50 degrees but only about 0.75-1mm high. They did a good job of cleaning up flange surfaces on various materials, but needed frequent re-sharpening. Carbide scraper blades were not a thing back then.
Thoroughly enjoyed that presentation. Thank you for sharing your findings. The second 'rubbing bevel' is similar to geometry on certain cabinet making edge work (wood work) and wood turning tooling. I have found the 'curling' cut which produces a broad curved scraping mark, helps enormously to reduce chatter on steel scraping. It does take some effort to take deep cuts, but 0.01mm depth is not so hard similar to that required for straight scraping. Thanks again for the video - Ive subscribed to see what else you get up to :-) All the best Mat
Excellent and very informative video... I've been considering build my own CNC mill, using granite/resin base and other parts. Part of this would be to use steel inlays for mounting the linear guides. Your technique for scraping carbon steel will come in very handy for making the steel inserts as flat as humanly possible prior to installation of the rails.Thanks for sharing... Very helpful content!
dankeshön ich hab seit tagen gewundert warum solche kratzer auftreten, ich dachte das ein grad beim karbid war weil ich kein feines schleifrad besitze. hat mich zur verzweifelung getrieben. also danke danke für dieses video
Dauert noch, ich habe keine Quelle für so flache Carbid Rohlinge und benutze deshalb alte Drehbank-einsetzplättchen die sehr dick sind, braucht ewig für so eine Geometrie.
My scraping was always bringing two(2) unequal surfaced ,on the same plane .profiled on any geometric surfaces. 😅.usually reserved as oil retention. Work hardened chemically or heat treatment. I was a witness of a true metalworking on a lathe with supper hard surface. He used a electric power scraper..the size of a gas hedge trimmer. 😮😊
When sharpening with diamond wheels, I always put the cut on the inside of the wheel, and cut from inner to outer. This way the front edge of the wheel does not wear out. Allowing for the ability to grind flat geometries, like making a D bit. I find that a very slight positive angle works very well, stops it from wanting to dig or bite into the steel. Having the heal to control works very well. I did not make as long a heel as you did, so will try your method on the next tool I make.
Very good observation, Sir. When I made this particular video, I wasn't aware yet that it's more smart to use diamond cup wheels radially from inside to outside. Robin Renzetti mentioned this recently in his video about making boring bars. Good point.
Interesting video. I am not an expert on this subject. My personal experience is that pull scraping works better on carbon steel rather the push scraping. I use same carbide blade as I use for cast iron
As the grain of the steel is softer and more ductile, your scraping blade should also be of a softer material. Therefore, my theoretical choice would be high speed steel. This would be my starting point. As you progress in tool geometry you could then start to compare and experiment with different high speed steels for your application. Do to the much higher graphite content of the cast iron, the harder blade will have a much better tendency to slide over the base material, compared to low carbon steel. Hence, not gouging the surface as your video clearly demonstrates.
Just found your videos and this will be extremely helpful for me right now. One question: does this also apply to mild steel? Because when I tried to scrape it with a regular insert (about 5° negative) it behaved pretty miserable.
Hey mate thought I'd share ONE WEIRD TRICK for carbon steel; I'm finding you can use the normal 5 deg angle on the carbide for cast iron and get a nice cut if (after blueing) you douse the surface in CRC or WD40 then take light cuts, keeping the tool on the surface to stop the chips getting underneath, you can still get some marring if your not careful but generally you can hear it when its not cutting properly, also keep cleaning the chips of the blade.
Thank you for your effort her Alex. I notice the sub count is going up every vidio of yours I watch. I kick myself for not cross referencing from other disciplines. In wood turning, when using the slicing technique, as opposed to the scraping technique, you balance the cutting action of a knife edge sharp cutting tool by rubbing the heal of the bevel on the rotating wood. This takes a bit of practice I can assure you and dig ins are.. Disasters.. I'll leave it at that. But the technique is the same principle.. Well done, thank you. Now where did I hide that scraper....
Sehr interessant und gut dargestellt, besonders das Papp-CAD, auch wenn ich wahrscheinlich nie Stahl schaben müssen werde. Was benutzt du denn für HM-Platten, die schauen ja wie Hobelmesser aus, aber von holzverarbeitendem Hartmetall wird meines Wissens immer abgeraten, was würdest du da empfehlen?
Die HM-Rohlinge, die ich hier zeige, hat mir ein Freund geschenkt. Deren Cobalt-Anteil oder ursprünglichen Verwendungszweck kenne ich leider nicht. Aber sie arbeiten bestens sowohl auf Stahl als auch auf Grauguss oder Aluminium, und das zählt für mich.
Hi Mads, very interesting idea, however, I think this would sooner or later become troublesome, since on the multi tools I know the lift is very little and not adjustable. This would slow down the scraping process notably, I think.
I teach people to scrape steel by hand and with power. You scrape steel by hand the same way as scraping cast iron. With a neg. 5 degree blade. Positive blade with a power scraper. This info was inside Stefan work booklet he received during the class. I will try your tip grinding method next time I scrape steel. You can teach old dogs new tricks .Rich King
Hello Mr. King! Many thanks for your comment, I'm very honored to find you were watching my video. Stefan already told me about the technique that you teach for scraping steel. Unfortunately I didn't have a chance so far to try it because I have no power scraper. Please let me know if the tip grind shown in the video works out for your steel scraping work. Best regards, Alex
An Engineer's Findings I seldom scrape steel anymore and have never had problems using the 5 degrees. If you have discovered the new way, congratulations. I scrape cast iron machine tool ways and would never make a steel straightedge. I make cast iron straightedges. As all other famous companies like Brown & Sharp never made steel straightedges. I've seem a steel rule made by Starrett but there not made for scraping.
Thanks for your nice comment, Mr. Bruun. The straightege is made up from two rods of carbon steel with a lasercut fillet welded in between. The fillet is designed to be most rigid in shear, which gives high bending rigidity of the assembly. The welds are critical in terms of the edge's precision over time. What matters most is to induce the least residual stresses with welding as possible.
@@madsbruun8423 Of course it is scraped, the technique for this is shown in this video (scraping of carbon steel!). I have no access to such a large surface grinding machine. Thanks, Alex
Vielen Dank für das sehr informative Video! Ich möchte mir um meine Fräse einzuschaben ein Tuschierlineal herstellen, das muss aber 700mm lang sein. Gekauft sind mir allerdings zu teuer und selbst wenn man rohes, Strang gegossenes Roheisen verwenden möchte kostet das immernoch 4 Euro pro Kilo :( meinst du man könnte auf dieser Art und Weise ein Tuschierlineal herstellen, ich habe vor allem Bedenken, ob sich das Lineal nach bestimmter Zeit durch Eigensspannungen wieder verzieht. Hast du Erfahrungen mit sowas?
I appreciate your effort but i dont see the problem you are trying to fix from the first place specially that your positive rake appear to dig into that steel which seems to me is cold rolled, i am assuming hot rolled will be even more challenging, I dont understand the initial problem that you faced since surface finish is not the goal in scraping AFAIK, hope you can explain more about this point, thanks
Excellent and thorough demonstration. I'll soon be making the fixtures to adapt my S0E to grind scraper inserts as you have shown. Very resourceful, thank you for showing those. Is that a steel straightedge (parallel?) that you fabricated yourself, shown at 0:50?
Yes, Donald, the straightedge shown is custom made for the purpose shown in the picture. It is a welded design (with carefully thought out weld design and strategy), made from carbon steel and scraped to my grade 00 surface plate (with a scraper blade as shown in the video). This straightedge cost me in total about €50 (mostly for the laser cut fillet-sheet) and I could fabricate and scrape it to finish in about 5-6 hours.
Outstanding, Alex! Sometime I'd love to hear more about your straightedge design and fabrication strategies. I assume that you went straight into scraping just after fabrication, with no need to surface grind?
That's right, Donald. I have no access to such a large surface grinding machine, so I rough it in with the angle grinder and then scrape it to precision finish from there.
all good, but every time I see you swipe those shavings I remember the "fun" of digging out steel splinters when I was cleaning my new to me mikron mill... use a brush, or even better - vacuum them up right away, I suggest researching iron rich foods if you want to absorb iron into your body :D p.s. are those press brake ram blades you're making there?
Thanks for the advice, but I haven't had problems with chips in my hands yet. More common to me is burnt skin from hot chips on the lathe or mill. Yes, the parts in the background are the jaws of my newly designed press brake.
yes, hot chips are a problem... I use pieces of plexiglass stuck in T slots to mitigate this, but regarding the "needles", in my case they were dirty with remnants of the coolant previous owners used, and it probably had some bacteria living in it still, because after digging them out, it wouldn't heal right away, worse then these was only carbon fiber epoxy strands stuck in the skin after part trimming, thick leather gloves solve the CF splinter issues, but with the steel ones, I tried thin rubber gloves, thick rubber gloves, leather gloves etc, and those splinters just kept moving through the glove into the skin, I'm no safety nazi, but that experience for me was in the same category as stringy stainless steel chips on the lathe - 99,99% chance of a cut if touched with bare hands Good luck on the press brake build, I'm in a quite dire need of a ~1m aprox 25t press brake myself, but I think I'll get something from the used tools market and do refurbishing if needed.
Bin absoluter Laie aber trotzdem schwer beeindruckt, dass mit der Schabetechnik derart ebene Flächen erreicht werden. Schaben erscheint mir wie Feilen, nur mit einer einzigen scharfen Kante. Könnte man Ratterer und Scharten eventuell einfach vermeiden, indem man z.B. ein 1x1 cm großes Feilenstück an der Spitze der Schaberstange benutzt, sodass man flächig abträgt?
Wenn man nur Schruppen würde, könnte das sein. Allerdings trägt man beim Schlicht-Schaben ja nur in Mikrometer-Größenordnung ab. Ich denke das funktioniert nur deshalb so kontrollierbar, weil man mit einer definiert im Eingriff befindlichen Schneide arbeitet.
I'm perplexed, all the scraping videos I've seen use a much different technique, like Robin Renzetti or even Stephan Gotteswinter, the cut is always in a singular direction, and a singular motion
@@anengineersfindings I'm perplexed as to why you are not using a similar technique, despite your results, which seem sufficient. . .they all seem to favor a "monodirectional" singular cut rather than the continuous motion that you were using.
