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Resusitating Some Chinese Iron

Discussion in 'MACHINE RESTORATION & WAY SCRAPING' started by Baithog, Dec 31, 2015.

  1. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    Quite a few years ago I finally managed to save up enough to buy a little HF mill. I had no illusions about the quality I was getting. Getting was way better than not getting at all. The ways were warped so that several inches of travel wouldn't travel. I lived with it for years, being creative about work piece sizes. A year or so ago I hung stepper motors on the little mill to do CNC. That made made the problem unworkable. Years of using nothing but the center of the table had aggravated the original problem with wear. CNC meant that I couldn't selectively lock one axis or the other, or do gib adjustments on the fly. So the machine saw little use. The sale of some of my other toys and a deal with my wife got me a larger mill/drill. I considered converting it to CNC, but I like the feel of manual control. It did occur to me that the mill/drill was just large enough to re-machine the X2's ways.

    Two weeks ago I got up the nerve to mill the X-axis table and saddle. Not being very patient, I assembled the table and saddle with the old gib. It slide smoothly from end to end with no wobble. I was very pleased with myself, but all was not well. Wear marks from the first slides showed that I had very little bearing surface. If I don't do something to smooth the ways, I will quickly be back to where I started. I have spent hours reading rancorous discussions on the net about the merits of lapping versus scraping.

    Enough of boring you with background. I think I want to scrape the ways, and I think that I have a plan. Assuming that I can teach myself to scrape, this is it.

    • Machine a cast iron dovetail master.
    • Scrape in the master.
    • Use the master to scrape in the bearing flats
    • Use the master to scrape in the table dovetail ( or should it be the saddle first?).
    • Scrape the saddle to the table.
    I plan to scrape in a block plane and a angle iron for practice. Does the above plan sound way too ambitious for a novice scrapist?

    Saddle
     
  2. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    Saddle
    Saddle.jpg
    Table
    X-Axis.jpg
     
  3. Ulma Doctor

    Ulma Doctor Infinitely Curious H-M Supporter-Premium

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    ambition is the key to success my friend.
    practice will assure your outcome.

    do this any way you wish, but i might suggest...

    if you have, or can get a surface plate of desired accuracy,
    you can scrape each flat surface from the surface plate's reference.
    then use the dovetail master you scraped from the surface plate to master the dovetails.
    it may save you some time.
     
    Last edited: Dec 31, 2015
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  4. timvercoe

    timvercoe United States Active Member Active Member

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    Gotta start somewhere...........Sounds like you have a good grasp on you plan and results..... a china man mill sounds like a worthy place to start.

    Tim
     
  5. gi_984

    gi_984 Active User Active Member

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    Second a surface plate. You are dealing with small mill parts and it is easy to roll out some bluing on the surface plate and spot the parts. Still have a tube each of the yellow and blue that "he who shall not be named here" gave me at the scraping class. I should of taken some pictures of my last scraping job to illustrate here. But you should find some videos on You Tube.
     
  6. astjp2

    astjp2 United States Active User Active Member

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    Gawd scraping is tedius, I have about 18 hours in both hand and powered scraping on my lathe saddle and cross feed. I am only about 1/4 of the way done. I was getting frustrated so I started to do 2 different pieces just so I could feel like I was making progress between the two. I have someone locally who has given me some pointers on scraping but I am still learning. I now have to make a new gib for the cross feed and eventually the compound rest. Here is some of what I have so far....Tim

    1227151505.jpg 1227151537.jpg 1229151347.jpg 1227151120.jpg 1230151332.jpg
     
  7. Uglydog

    Uglydog United States Active User H-M Supporter-Premium

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    Yes, scraping can be tedious.
    However, it fun for me to watch and understand that observing a real machine tool rebuilder scrape is efficient and quick. Seems job that takes me several hours takes them 20minutes.
    And their results are better!!
    Practice....

    Daryl
    MN
     
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  8. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    I am working my way through "Machine Tool Reconditioning". The description of how to sharpen the scraper has me confused as to what I'm trying to achieve. I sacrificed a very worn Nicholson
    file and was not able to get it to cut cast iron. It would help to have a properly sharpened scraper to examine and try out, So I guess I have to get off the pot and order a real scraper. I am tempted to get an 18" tubular handle with a HSS blade. I can hone HSS as I have hard arkansas stones and razor hones for my plane irons. That way I can start experimenting with the angle plate. On the other hand I will probably have to get a carbide blade eventually and build a lapper.

    I found some descriptions of home built lapping setups. They are based on available motors. Most of the descriptions use a cast iron face wheel. There was at least one mention of using aluminum or brass for the wheel. I have 5" aluminum stock. Would embedding diamond past into aluminum really work?

    Is 9micron the right paste, or should I go down to 7micron?
     
  9. Ulma Doctor

    Ulma Doctor Infinitely Curious H-M Supporter-Premium

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    to make a scraper from a file, you'll want the edge to be at about 3*negative rake
    or you can make a sharpener like i made...
     
  10. Uglydog

    Uglydog United States Active User H-M Supporter-Premium

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  11. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    I am back to the project now that the Christmas decorations are back in storage. I have a 9X12, B-grade granite plate. I would gotten a bigger one with a ledge if I had known I was going to go this route. I ordered an Anderson Tubular, 18" scraper with a HSS blade, tubes of Canode red and blue spotting ink, a 2" brayer, and a better indicator holder. I am bidding on a Tesa Tast indicator with a resolution of 0.00005" and a +/-.004 range to compliment my 5 tents resolution indicator. I probably won't win it, but I'll keep looking a a 1 tenth indicator. I know that I will be converting to carbide eventually, so I'm also looking for a used motor to spin a diamond wheel. I should have enough toys to start butchering and angle plate later next week.

    I decided to take some rough measurements of the X slide bearing surface, just to see how nasty my machining was. The X dovetails and bearing surface were machined with the table top as the reference surface. I used both my 5 tenth test indicator and my depth micrometer to measure the left, center, right height of both bearing surfaces. Both instruments agreed, which was satisfying in itself. The measurements are in the photo attached. The bearing surfaces are slightly concave, which I suspect are easier for a novice to deal with.
    IMG_1185.JPG
    .2155, .2150, .2165 top
    .2160, .2145, .2165 bottom
     
  12. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    You are going to need a longer surface plate for scraping the slide to, unless you you have a camel back type of straight edge to use. Those numbers are not too bad, I usually find the numbers to vary as much as .030" and more on slides I've worked on in my past. If I got a worn out slide back to within .0015-.002" at any place measured, I called it good as long as the way members were flat to a surface plate or straight edge.

    Start out heavy scraping the ends to about 3" in on each end. Take impressions, and probably add on another 2"-3" to scrape. By then, you should start getting marks from end to end, not many, but a few. That will at least let you know where you stand on scraping.
    Ken
     
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  13. chevydyl

    chevydyl United States Active User Active Member

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    Before I got my connelly book, I was able to sharpen my file to cut iron, ground the breast on the bench grinder, and ground the teeth off the back side, laid it on the surface grinder to make the ground off teeth area flat, then honed that to a slight reflection on my fine diamond knife sharpener, then began working the breast on the same sharpener, here's a tip, use a sharpie to color the breast so you can see that your actually honing the cutting edge, also drag the cutting edge on your thumbnail, if it will flake your nail, it should push cut iron, at least mine did, it even cut steel for a couple strokes before needing refreshed lol. I'll take some pictures here after a bit to help you out
     
  14. chevydyl

    chevydyl United States Active User Active Member

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    Ulma, Richard king suggests spinning that motor to like 1500rpm, and also tilt the table down towards the wheel to avoid chipping the blade. Those were tips I read about from the master
     
  15. chevydyl

    chevydyl United States Active User Active Member

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    here are the pictures and how my blade is sharpened, when honing the blade I would rotate it on the breast parallel with the radius, rather than how it says in the connely book, but also in the book it says to have a flat edge in the part I read, maybe I skipped a part because I listened to what RK said about radius size pertinent to what type of scrape your after, large radius for roughing and small radius for pin pointing. this radius is in the middle of the road I believe. first time ive made one, I just wanted to try it out before my sandvik scraper and blades arrive.

    scraper1.jpg scraper2.jpg scraper3.jpg
     
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  16. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Richard King said that 1500 RPM is too fast. You need to get the RPM down around 250-350 RPM. You're lapping the edge of the carbide with a diamond lap of about 600 grit. 1500 RPM will burn the edge to where it will not cut properly. Don't get me wrong here, you can make it work, but I've been in Richard's present and heard him say you need a diamond disk running at a lower RPM than standard motor RPM. The Glendo he carries around to his classes only turns around 250-350 RPM. I have an older model of one that looks like the Glendo and it turns around 250 RPM. Originally used to put an honed edge on carbide turning tools. Worked quite well on my scraping tools, too.
     
    Last edited: Jan 17, 2016
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  17. chevydyl

    chevydyl United States Active User Active Member

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    Maybe it was a typo then, cause it said 1500
     
  18. Ulma Doctor

    Ulma Doctor Infinitely Curious H-M Supporter-Premium

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    I took RK's class too, here in CA

    i patterned my sharpener off a glendo sharpener.
    Glendo sharpeners operate at slow speeds
     
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  19. chevydyl

    chevydyl United States Active User Active Member

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    The speed thing must have been a typo then, but for sure it's recommended to tilt the table down towards the wheel to avoid micro chipping the carbide cutting edge
     
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  20. Ulma Doctor

    Ulma Doctor Infinitely Curious H-M Supporter-Premium

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    my motor is tipped to 3*, the table is flat.
    the effect is the same, regardless of whether the table or the grinding stone is pitched.
    the glendo sharpener had a perpendicular wheel and a tilting table
    i have a perpendicular table and a tilting wheel, the effect is the very same 3* rake.
    there are many ways of accomplishing the same thing regardless of professional opinion.;)
     
    Last edited: Jan 17, 2016
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  21. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    I'm not going to argue over 3 deg. I've always set mine for 5 deg tilt in to the grinding wheel. Of course, back in the day, the only thing I available was some worn out 6" OD diamond grinding wheels that were worn down to the aluminum in places. And I hand ground the radius tilting the hand scraper as needed to get the negative angle needed on the face of the carbide. Scraped a tone of cast iron that way. When I got a T & C grinder, used the same wheel, but had the all angle vise set up to the angle needed.

    Boy, we are getting off topic here... IT's all good!!!
     
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  22. chevydyl

    chevydyl United States Active User Active Member

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    How far out of whack is my relief angle, I just off hand ground the thing to what a picture looked like, what I have found is all the masters talk about how to do it but never actually show good pictures of the blades up close, in a way that's easy for the super noob to understand what is going on. My blade cuts but I ruined the temper grinding the radius
     
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  23. chevydyl

    chevydyl United States Active User Active Member

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    Really hard to tell that the wheel is tipped, thanks for pointing that out
     
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  24. Ulma Doctor

    Ulma Doctor Infinitely Curious H-M Supporter-Premium

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    something i tried when i was using a file for a scraper, i'd make the file radius on the end and no relief to the cutting edge.
    it cut much better than a relieved blade, but it does need to be resharpened frequently.
    it was a little harder to push, but it could remove a lot of metal in a single pass.
     
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  25. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    I'm really enjoying the conversation on sharpening. I have been replacing carpet with a new hard surface floor in one of the bedrooms. I received a brayer, red and blue canode ink, and an Anderson hollow scraper handle with a HSS blade while I was otherwise occupied. I will eventually get a carbide blade, but I need to build my diamond hone first. Is 150rpm too slow?

    I need to get the HSS blade profiled and sharpened so I can scrape something. I've seen that 600 grit diamond is fine for carbide, but what grit do I need for final pass on HSS?
     
  26. 4gsr

    4gsr Global Moderator Staff Member H-M Supporter-Premium

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    Don't use diamond on HSS, that is meant to sharpen carbide. They sell CBN wheels for HSS that are specifically for HSS. And 150 RPM is about where you want to be, 350 RPM max. The Glendo units run at about 250 RPM, about a 7:1 ratio with a 1725 RPM motor. My old Lenard Grind O Lap runs at about 200 RPM.
     
    Last edited: Jan 18, 2016
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  27. Joe in Oz

    Joe in Oz Australia Active User Active Member

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    Using diamond on HSS (or any steel) is OK if the process has a low surface speed. Diamond dissolves in HOT steel but cuts COLD steel perfectly well. WHen I say 'hot' I mean as in 'sparks'. If there are no sparks its not going to disolve the diamond.

    By the way, scraping with HSS or a file is VERY tedius. You spend 1/4 of your time sharpening or fighting with a blunt edge. Go straight to a fine grained carbide and sharpen every 2-4 hours scraping....
     
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  28. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    I am well aware of the reputation of HSS for being tedious, but then scraping is tedious. I'm not sure that I have the personality of patience to scrape. I could get by lapping off the machining peaks, or even putting the mill back together 'as machined' and have it work. That is essentially what Seig did when they manufactured it. So, if after some practice pieces, it turns out I'm just way too bored to deal with a scraping project, then I won't have wasted my money setting up to scrape with carbide. I am cheap enough that I would kick myself for not getting that co-ax gauge I've been wanting instead. On the other hand, if scraping is cool, I can set up for carbide and relegate my HSS blade to softer metals. Aluminum bronze gibs come to mind.

    My suspicions about diamond wheels was that there would be little migration of carbon at low speed, especially with some coolant. Iron has some interesting phase changes as temperature goes up, so figuring solid solubility and doping levels for carbon into iron is way more than I want to deal with. We had books of diffusion graphs back when I still worked in a silicon foundry, so we didn't even go through the pain of calculation then.

    I started sharpening my scraper last night. Connelly talks about polishing off the pits on the side of the blade. I didn't understand where the pits came from until I looked at the commercial HSS blade. It looks like it was sand cast. My previous experience with HSS tools were with ground ones. I would have been happy to pay another dollar or two to have gotten a ground blade. I don't have a course bench stone, so I had to order one. Polishing the flats on my Arkansas stones is painful. I am still wondering how fine a grit I need for honing the HSS cutting edge.
     
  29. Baithog

    Baithog United States Florida Machinist Group Moderator H-M Supporter-Premium

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    I got my course/fine india stone yesterday and spent an hour or so working on the flats of the blade. They aren't as nice as I would like, but the pitting is off the cutting edge. A surface grinder would be nice for times like this, so I'll add it to the 'some day' list. I put a 3" radius on the blade and honed a secondary bevel at about 5 degrees. It cuts fingernails. It even cuts cast iron.

    So I couldn't resist trying it out. I cleaned up everything on the bench and sqeezed a drop out of the blue canode. Except that the nozzle was clogged. After cleaning a quarter oz of ink off the plate, I was able to spread a thin layer and ink up the block plane. I forgot to take a picture of the first impression, so this is the second.
    Plane1.jpg
    I'm having trouble controlling the blade, and it is hard to tell just where it is going to cut. I think that a smaller radius would work better, but maybe I just need way more practice. I forgot to stone between impressions for the first few goes. Things started improving when I remembered. This is where I stopped for the night. Contact is growing.
    Plane2.jpg
     
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  30. chevydyl

    chevydyl United States Active User Active Member

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    I'm hooked on scraping now, it does appear that your cutting edge is not good, looks like it is scratching in a few spots, over in the potd I posted a pic of an initial rough scrape, insane how much better the sandvik carbide blanks are over the file I sharpened, although the radius is huge on them, they need to be shaped. I'll be following you progress.
    I seen someone put a mark on the cutting edge so they could have better sight of where it's going to cut.
    Maybe you said already but what kind of scraper handle are you using? My sandvik is pretty stiff, I may thin it out so it has a little flex to it.
     

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