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  1. #241
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    Quote Originally Posted by Richard King View Post
    I have thousands of satisfied customers and students who I am dam proud of who used to enjoy coming in here to ask questions. They emailed me asking to return because so much BS was being spread in here. I came back and saw for myself. After the last go around more came back and asked question when you and the "buddies" left and played elsewhere. All was fine until there you were again... I offered a peace treaty, but it appears you want to continue. You scraped years ago? What exactly did you scrape and where did you teach?

    Like I said...I teach facts and Not made up BS. You may see it as ego. I see it as skilled craftsmanship I share. My students on here accept one or 2 guys who have chips on their shoulders. Maybe .02% of all my students have issues. I will be teaching a class in Springfield Vermont in April...how about you Bill come up and teach us something. Also Ewstley I will be teaching another class next month in Rockford IL. at Bourn & Koch...come on over and teach us something. Your both invited and can come no charge...be my guests.
    Do you ever go South to say Texas?

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    Quote Originally Posted by radiocontrolhead View Post
    Finally had the dovetail straight edge delivered and not sure if the quality was as high as it could have been as there are some voids here and there.

    the face that I wanted to start scraping was pretty rough. I don't have access to a mill so I'm doing it manual style. Decided to draw file the lower third of the straight edge and began to rough scrape it to some kind of flatness for now. Next is to continue draw filing the remaining portions of the straight edge and begin spotting.

    To my surprise, this cast iron is significantly harder than the soft Chinese "iron".

    Question, Is it okay to leave very small pin hole voids on the scraped surface? I have very few of them.

    Attachment 221586

    Attachment 221587

    Attachment 221588
    Yeah when pitting occurs people will machine or try to grind them out often. Yet in your case if the pits still allow you to scrape a good percentage of metal that may be the way. I do not know for sure,I am approaching it from a perspective of honing and hand stoning out of wak surfaces which is not as complex as what you are doing. I know it makes a huge difference scapping and I find it very interesting. I would prefer I would not have to be in circumstances which required me to scrape to bring it in. If I had to I would like y’all do it. No prob,gung ho.

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    Quote Originally Posted by Spinit View Post
    Well from what you mention you obviously need your boss to get you some tooling. I suppose you may be able to file them all yet there is the real trick thing can you do it? Also one other thing does your boss wish you to do it or do they want to do something else while he orders tooling. I woul not wish a filing job like that on anyone it is too much sticks and stones machining.
    "Case anyone else has missed it, 'coz he said so, and even shows a corner of the very table in a photo or two, this is LITERALLY a "kitchen table" experimenter at work here, teaching himself from a cold-start, and on "small money", but somewhat larger rations of patience, guts, and won't-quit-willpower.

    The only "boss" being the demands of a spouse and household budget with other, higher priorities, as they most always have to ultimately be for any of us.

    AFAIK "rch" is not even in the metalworking biz as "Day Job? Or at least not as a "machinist", let alone a rebuilder.

    And.. that apples to many others here as well in one degree or another.

    Some truly lovely scraping has become the hard-earned skill of dedicated folks who do - of have - earned their crust in metalworking but have other, more demanding deadlines and priorities than any more scraping than there is time and money to pay for - or who do not work in metalworking AT ALL, but entirely unrelated occupations, rather.

    Good on 'em. Thank you, one and all.

    It is inspirational as can be as to what "HUMAN, Type One Class One, Standard "A", GENERAL PURPOSE" can still-yet accomplish in the ear-bud and instant-gratification age!

    Not a one among those - not ONE - has yet demanded his global stature be glorified, or that any part of his anatomy be stroked, kissed, otherwise anointed, nor be paid repetitive homage to.

    Not ONE!

    THESE contributors, are the ones others can learn the best and most from without all the messy "rationing out", head-games, and psychological OVERHEAD constantly creating barriers to progress faster than it helps one go beyond those barriers.

    Pleased to see it carry on.

    Thanks again, one and all for just treating it as what it is.

    One more challenging skill among many thousands of OTHER challenging skills.

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  5. #244
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    radio control head,

    Go get that straight edge stress relieved and rescrape it straight again. That's the only way you are going to stop it from moving around on you. And have them to heat it high enough to get rid of the chilled iron in it. Furnace cool slowly to near ambient.

    Ken

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    Oh yeah if it is in the state of being chilled cast iron it is hard as heck. I would machine rock crushers that were chilled cast iron way back in the day and the only insert that would hold up was ceramic. I mean super hard.

    I never wanted to machine that stuff again and I have been lucky as I have not seen it since. Sometimes we get a brake

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  8. #246
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    Quote Originally Posted by 4GSR View Post
    radio control head,

    Go get that straight edge stress relieved and rescrape it straight again. That's the only way you are going to stop it from moving around on you. And have them to heat it high enough to get rid of the chilled iron in it. Furnace cool slowly to near ambient.

    Ken


    Would stress relieving remove all residual stresses in the part even those resulting from improper cooling or any hardness effects that may have occurred during the casting/cooling process?


    The reason I ask is because i contacted the supplier of my casting and they are awesome enough to send me another casting. The issue i have though is that if I can fix what i have now by means of stress relieving, i would rather keep it since it's already been machined on all sides and ask for a credit toward one of their other cool castings...

    If there is a point where cast iron gets hardened and CANNOT be reversed to relieve stresses then forget what I said above.

    Thanks

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    Quote Originally Posted by radiocontrolhead View Post
    CANNOT be reversed to relieve stresses then forget what I said above.
    Metals? There isn't a lot of "CANNOT". They get seriously grotty, one simply smelts them, fluxes out any dross, touches up the alloying, and casts all over again.

    Not worth so much per ton. Not worth waste of too much fuel or electricity, let alone TIME to f**k-with.

    Figures are all over the 'net. Commodities trade globally all day, so does scrap:

    Iron ingot price - Trade Metal Portal).

    Too much time wasted - as your supplier just showed you - and you just scrap and start over. Cheaper that way. Not as if it were a child or even a puppy dog.

    Just dead metal left over from death of a star, long, long time ago, and very far off, now.

    Don't "marry it". It's a promiscuous whore anyway.



    PS: You don't want to keep the old one. Supplier did you a good turn. If they'll take it, ship it back so they have sight of it and have a better idea what went awry.

    Even if "what went awry" was YOU, there can be a benefit to all-hands just knowing that.


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  11. #248
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    I'm not a metallurgist. One of the few axioms I know is that stress-relieving cast iron is done around 1200°F because at that temperature it is soft enough to relax most of the internal stresses without influencing (too much) the hardness. I believe that, at around 13-1400°F, you get metallurgical transformations. I know that cast iron could be transformed into ductile iron, with the graphite condensing into small beads (in gray cast iron, I believe it is in tiny sheets). But I'm not sure if you can transform white into gray cast iron without remelting (if I recall correctly, in white cast iron the graphite is mostly precipitated off the mix).
    As I've said, I'm not a metallurgist and my knowledge in the field is rather limited. However, I believe that you would need a non-standard heat treatment and you would have still relatively high chances that your piece would be still hard like a rock after the treatment.
    Those curly chips would lead me to think that the alloy, the melting, etc. was screwed up in the first place.

    Paolo

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  13. #249
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    Thanks Thermite and Paolo,

    I'll sit tight and wait for the new casting to arrive with fingers crossed. In the meantime i'll be scraping the toy castings and get as far as i can with them.

    .at this point I'll do just about anything just to stop the bleeding... which would be to pick up a camelback.. if Richard would even sell one to me anymore,

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    Quote Originally Posted by radiocontrolhead View Post
    Thanks Thermite and Paolo,

    I'll sit tight and wait for the new casting to arrive with fingers crossed. In the meantime i'll be scraping the toy castings and get as far as i can with them.

    .at this point I'll do just about anything just to stop the bleeding... which would be to pick up a camelback.. if Richard would even sell one to me anymore,
    Don't rub salt. All pain, no gain. He was shirty when I called him on the phone after he'd already shipped me his video and a brand-new copy of Connolley's book a while back. Said he'd not have done it if he'd know who I was!

    I later bought a Biax blade from him. With which, obviously, I must be limiting myself to the scraping of PAINT given what a worthless piece of shit anyone who hasn't paid for his courses must be at any sort of human endeavour of any kind.

    Ten thousand competent scraping hands looking for trade, the world around - and we'd have to go and hire a wannabee Walrus with a psychosis as a tenured professor?

    Not on MY damned dime, thanks!



    Meanwhile... what length - and what TYPE of SE - d'yah actually NEED, now that you know more about the bigger picture? Think short-term and "longer term" needs.

    That mini-blivet? Mought make more sense one of us just LEND you one before you overflow the kitchen and git yerself kicked outta the bedroom with more toolign than the MMSO itself takes up, let aloen any intrinsic worth to it.

    Faster to just get that off yer plate before it traps you into long-term idiocy, not temporary.

    DAMHKT carrying a 6" X 18" @las "LSO" as "ballast", new 1968 - scrapped 2017. Last time I recall using it, was for a part on the '72 "Bavaria" I traded on a Suburu 1800 DL nano-wagon .. around 1981? As said "ballast".

    Last edited by thermite; 06-12-2018 at 02:18 PM.

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    Quote Originally Posted by thermite View Post
    Don't rub salt. All pain, no gain.

    What length - and what TYPE - d'yah actually NEED, now that you know more about the bigger picture? Think short-term and "longer term" needs.

    That mini-blivet, mought make more sense one of us just LEND you one before you overflow the kitchen and git yerself kicked outta the bedroom.

    Faster to just get that off yer plate before it traps you into long-term idiocy, not temporary.

    DAMHKT carrying a 6" X 18" @las "LSO" as "ballast", new 1968 - scrapped 2017. Last time I recall using it, was for a part on the '72 "Bavaria" I traded on a Suburu 1800 DL nano-wagon .. around 1981? As said "ballast".

    18" SE is what I have now (rather 18" of hardened Cast iron) and it covers quite a bit of real estate on the mill. It's the largest I can effectively use since i'm limited by my surface plate.

    Suppose I never thought to borrow one. that would get me straight through the guts of this project rather quickly.

    I've taken a strong interest in scraping and learning it could serve quite a bit for when I decide to purchase used machinery or more import crap () and decide to overhaul them in the future. A lathe and a surface grinder are in mind in the future so having a legit SE would be a nice tool to have around. I'm treating the noodle prism SE as a temporary tool.

    Not expecting to be in this small space for very long but for the time being it is short term.

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    white-iron2.jpg
    Quote Originally Posted by radiocontrolhead View Post
    18" SE is what I have now (rather 18" of hardened Cast iron) and it covers quite a bit of real estate on the mill. It's the largest I can effectively use since i'm limited by my surface plate.

    Suppose I never thought to borrow one. that would get me straight through the guts of this project rather quickly.

    I've taken a strong interest in scraping and learning it could serve quite a bit for when I decide to purchase used machinery or more import crap () and decide to overhaul them in the future. A lathe and a surface grinder are in mind in the future so having a legit SE would be a nice tool to have around. I'm treating the noodle prism SE as a temporary tool.

    Not expecting to be in this small space for very long but for the time being it is short term.
    I think you will be frustrated in trying to heat treat your presumably (not so sure about that---more on that later) white iron casting into something resembling grey cast iron in its machining (including scraping) characteristics. As pointed out in a post above the crystal structure of white iron is substantially different than grey iron. Short of remelting what you have, you cannot reverse that cruystal formation and then have it proceed in the grey iron direction.

    Cast irons

    A while back, for fun, I tried converting a white iron sash weight into a machinable state by heating up to something like 1700 degrees and then aloowing it to cool over several hours. Doing so made only a slight difference----prior to heat treating it a 1/4"carbide drill barely would even touch it despite high pressure in BP mill and low RPM. After heat treating I could barely make a hole it it a half inch deep with max pressure and a good sharp carbide drill. The heat treated lump was hardly usable for anything, except a sash weight! ;-)

    I am skeptical of your casting being white iron as I doubt it would be possible to scrape such even to the degree shown. Might be wrong, just sayin. If you could bring yourself to sacrifice a corner of your (otherwise more or less useless) casting and break off a piece, the question could be answered. For instance, using an angle grinder and cutoff blade, score the corner to remove say 3/8 or half inch of the casting by making a cut 1/3 of the way into the casting on top and bottom leaving 1/3 of the casting intact. Then strike the corner with a hammer---won't take much and you will fracture the corner off. A look at the fractured surface will answer the question immediately and definitively. White iron will have a decidedly white color and sparkly crystal structure. The grey will be dull and grey.

    Attached is a photo comparing grey and white iron that I made a few days ago. By the way, those two samples of cast iron were cast from the exact same ALLOYS of iron, only the post-casting treatment was different. The white iron was intentionally cooled very rapidly, the grey was allowed to cool gently. This is a clear demonstration that how a casting is managed immediately after it is cast can have dramatic effects on it machining and scraping properties later on.

    Denis

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    I'd suggest the OP not bother with machining or scraping another Coreprint prism. Instead get one of the following: Richard King's 18" SE, Craig Donges 18" SE (not sure if available new?), Metal Lathe Accesories 18" fitters straight edge (not available as castings anymore- would have to find used). I have a 24" and 48" King dovetail SE scraped by me and in use (the 48" was machined for me by Collector). I would assume Richard's 18" would also be an easy to machine and scrape, stable reference tool. I also machined and scraped the MLA fitters SE. All three are good tools to start with, from my experience, and will work for your current project.

    You've gained valuable experience with your attempted prism. Now make a proper straight edge you can use.

    Lucky7

    Ps- if you can fit Richard's 24" SE with dovetail diagonally on your current surface plate, that's the one I'd get.

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    Quote Originally Posted by radiocontrolhead View Post
    18" SE is what I have now (rather 18" of hardened Cast iron) and it covers quite a bit of real estate on the mill. It's the largest I can effectively use since i'm limited by my surface plate.
    Severe limitation and over long, long years, a plate too small. My 18" x 24" B&S hasn't even seen the light of day since the 48" X 30" Herman was set back on its factory stand. 30" rather than 36" width lets me move it through the 36" doors, shop to layout/metrology/tool crib area. Keep that in mind for "futures", 'coz a 48" is about the shortest practical for any serious SP work.

    Or so sayeth a paint scraping "fake", anyway.



    Prisms cannot help but be "noodles". They need extra care as transfer devices. That's the unavoidable trade-off for having "something" that one can at least get INTO certain places where a camelback with dovetailed edge on its sole just cannot go.

    NONE of your SE's are "reference" devices, BTW. Your SP is that.

    Imperfect, always, but the best we have under-roof, and more than good enough. The SE's are for transfer, full stop.

    Annnd.. NO NEED for you to go a lot further down their road in any case. A fine collection of seldom/never-used SE's does not translate to wealth or skill.

    Not unless scraping is to become your sole and only way to pay the mortgage.

    Perish the very thought!

    On the evidence, that sort of intensity of ever-narrower focus on elevation to divine status can lead to anti-social behaviour, if not multiple personality disorder - even borderline madness.



    You may want to start shifting your focus to the more creative side of the mangling of matter?

    "Scraping" after all, is merely closely controlled destruction.

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    little update:

    Got a refund for my prism SE and went ahead and purchased one of RK's 12" SE. Had it machined and went to scraping. I'll tell you... after scraping that hardened prism SE this is such a joy to scrape. I've been having a great time doing it. Got the rough scraping complete in about 3 hours of hand scraping (was pretty flat) and now i'm moving on to finish scraping.

    Few pictures below of the "set up" and limited work space.
    Attached Thumbnails Attached Thumbnails 20180712_055737a.jpg   20180712_162816a.jpg   20180711_043339a.jpg   20180712_061931a.jpg   20180712_080117a.jpg  


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