Backplate runout - Page 2
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  1. #21
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    Quote Originally Posted by iwananew10K View Post
    how are you checking it?
    (with what, how are you turning the spindle, ect)

    is it always in the same place no matter what?

    sometimes even a hard spot can cause the tool to not quite cut the same as the rest and look like runout.
    second that, cheap cast iron (any cast iron really, but WAY more likely in cheap stuff) can have some very hard spots in it. in fact once got some cheap pre-threaded backplate blanks (a while ago, don't have threaded spindles in use now) that were basically un-machinable even with carbide. had to send them through a 10 hr furnace cycle to get them into a reasonable state to work them.

    you can usually tell by the sound of the cut, and the presence of really bright shiny spots if thats what is going on.
    what are you cutting them with, HHS or carbide? .0015 is a lot if you are facing them off on the spindle, should be able to get better that that.

  2. #22
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    for almost all my turning I've been usin the HSS inserts from AR Warner. I did use some braised Carbide I had , (no idea what type it was)
    for cutting register after facing the back of the backplate . not sure what that part is called the small part on a backplate , I was thinkin spigot , but not sure . I don't think I can get any better that the .0015 due to the finish , I think if the finish was better that # would be lower
    animal

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    Quote Originally Posted by animal12 View Post
    for almost all my turning I've been usin the HSS inserts from AR Warner. I did use some braised Carbide I had , (no idea what type it was)
    for cutting register after facing the back of the backplate . not sure what that part is called the small part on a backplate , I was thinkin spigot , but not sure . I don't think I can get any better that the .0015 due to the finish , I think if the finish was better that # would be lower
    animal
    if your as turned surface roughness on a finish pass is .0015 you have issues. try a sharp carbide tool, (inspect with a 10X loupe), look for the shiny "high islands", review all basics for turning like rake angles, hight of tool, backlash on cross slide and compound, runout of spindle etc,etc, but thats not good.

  4. #24
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    I'll hit it tomorrow with some fresh eyes & a magnifier , I know the surface is rough . I nrever bought any carbide cause all the readin i did said these lathes don't run fast enough for carbide
    thanks

    animal

  5. #25
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    so my insert holders take TPMT inserts , any input on what type carbide I should get is appreciated
    animal

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    what size inserts? 222?

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    Quote Originally Posted by animal12 View Post
    so my insert holders take TPMT inserts , any input on what type carbide I should get is appreciated
    animal
    Sandvic, Iscar , kennametal , Walter or another name brand likely fine/OK. I would blue what ever is mating your spindle register to be sure a good and square to mate thread and face. Mating harder on one side/blue and likely you will still/may have a problem. If I had to hand hone one side to make a good mate I would do so. Guess I would want the lathe spindle register to run very good also, near zero.

  8. #28
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    sorry bout that , their 222 . I gonna head out to the shop in a few & blue up the backplate & see what I have . & also look & see if I still have any races in my tool box
    thanks
    animal

  9. #29
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    for a little job like this anything with a positive rake would work. they make grades specifically for cast iron, but unless you cut a lot of that, get one for steel and cast iron

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