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Impressive $20 brake rotor for tramming the mill

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  • luthor
    replied
    Originally posted by Bented View Post
    5 10 millionths, impressive to say the least. How did you measure this ?
    I use granite surface plates that will not measure that well.
    My thoughts exactly Bented, I think the OP was dreaming when he posted 10+ years ago.

    Leave a comment:


  • old mart
    replied
    Having the use of 2 mills, a round column drill mill and a lightweight knee mill, they both have the same tramming fault. With a 63mm shell mill, the double set of lines left is perfect in one X axis direction, but if cutting in the other X axis direction, then only one set of lines. The DM isn't ammenable to easy tramming, but the knee mill can be trammed with difficulty, we took an hour to do it and I would need a very good excuse to tilt the head on it in the future.

    Leave a comment:


  • Bented
    replied
    Originally posted by nheng View Post
    .

    Rotor thickness variation measured at 4 quadrants, at 2 diameters:

    +/- 0.00005"
    5 10 millionths, impressive to say the least. How did you measure this ?
    I use granite surface plates that will not measure that well.

    Last edited by Bented; 07-15-2021, 08:43 PM.

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  • reggie_obe
    replied
    Move along guys, nothing new to see here.....
    Ten plus year old necro thread.

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  • Paul Alciatore
    replied
    While the rotor the OP measured is probably very flat, his described measurements did not seem to address flatness, only parallelism.



    Originally posted by lazlo View Post
    Yeah Den, I'm really surprised too at the precision of that rotor. What brand did you ask for at Autozone?

    I never understood why folks don't like to use the mill's table directly: if you bend the DTI needle in the direction you're sweeping, the T-slots don't hurt the gage, but heck, it's nice to know that you can buy a "precision flat" for $20 at your local AutoZone.

    Leave a comment:


  • Fasturn
    replied
    I would always laugh at machinist making a 20 inch sweep on a bridgeport mill. Gee does the quill extend that far? For me I sweep maybe an inch / 25mm past what the quill will extend. Good enough for government work. No money in tramming the head to .000001 ??

    Leave a comment:


  • Rosco-P
    Guest replied
    Originally posted by gnm109
    JB Weld!!! Thumbs up!

    If I ever build my dream home, the kitchen will have several taps.

    1. Hot water.
    2. Cold Water.
    3. Ketchup.
    4. Skippy Peanut Butter.
    5. Heinz Ketchup.
    6. JB Weld
    7. JB Weld Hardener.
    8. Beer.
    9. Hand Cleaner

    Leave a comment:


  • jetski781
    replied
    do, can't say I've ever done it but there were a couple of people at the start of this thread that claimed to do it. There are also quite a few people that think .001 is a really tight tolerance.

    Leave a comment:


  • dp
    replied
    Originally posted by jetski781
    Place your vise on the table and say it is out of parallelism to the table by .010 over 6". Now, tram the head to the vise.
    Do people do that?

    Leave a comment:


  • dalee100
    replied
    Originally posted by lane
    All I know for sure is DONT mention the word Precision on this forum Man people get carried away . If you only worked in a real shop all day every You would then know the truth in the real world. .Precision is nice but we often do not have it just get it done.

    Hi,

    Ain't that the truth. We always need to ask, how good does good enough need to be.

    dalee

    Leave a comment:


  • gnm109
    Guest replied
    Originally posted by A.K. Boomer
    That's what I also wonder, go directly to the horses mouth and eliminate error (dont have to worry about crumbs between the two surfaces or if the second surface is precision enough)
    All mill tables iv ever seen have a hefty chamfer, the only way to get in trouble is to go too deep with the indicator needle so just dont do it, I just skim aprox. .010" --- Lazlo throws in another failsafe with his paying attention to the direction of which way the needle is dragging (not pushing) Set your mill up to its rough alignment degree marks first, if they dont match up then either make them or mark them so you know when its very close, that way you wont lose your indicator ball below its radius --- So you have an old mill with tons of dummy marks in the table?, take a putty knife fill them all with JB weld let harden and stone them in, it should be done anyways to keep chips out so you can install your vise and RT table and other stuff without dredging up swarf between the two surfaces...
    If your mills table has jewling or etching then just stop the needle on a flat

    JB Weld!!! Thumbs up!

    If I ever build my dream home, the kitchen will have several taps.

    1. Hot water.
    2. Cold Water.
    3. Ketchup.
    4. Skippy Peanut Butter.
    5. Heinz Ketchup.
    6. JB Weld
    7. JB Weld Hardener.
    8. Beer.

    Leave a comment:


  • lane
    replied
    sorry double post

    Leave a comment:


  • lane
    replied
    All I know for sure is DONT mention the word Precision on this forum Man people get carried away . If you only worked in a real shop all day every You would then know the truth in the real world. .Precision is nice but we often do not have it just get it done.
    Last edited by lane; 12-04-2010, 09:39 PM.

    Leave a comment:


  • jetski781
    replied
    I see a couple of guys on this thread tram the head to the table, vise, or whatever they working off of.

    Assuming that the table surface is parallel to the ways and perpendicular to the spindle. Place your vise on the table and say it is out of parallelism to the table by .010 over 6". Now, tram the head to the vise. You place a piece of ground flat stock in the vise and we will assume that the bottom is perfectly parallel to the vise. Take a face cut across the flat stock and you will find that it is no longer parallel top to bottom, it will have the same .010 taper that the vice had to the table. You can easily see this if you set your vise up with a shim under one side tram the head to the vise then take a DTI and run it across the surface of the vise using the table hand crank from side to side.

    Food for thought.

    Leave a comment:


  • noah katz
    replied
    "Bridgeports and their related kin are as rigid as wet noodles.It is very much possible for a two flute 3/4" endmill to chatter a BP head out of tram."

    Is that in both axes?

    Would taper pins keep it in place?

    You could drill and thread them for jackscrews to push them out.

    Leave a comment:

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