Centering a hub and bolt circle - Page 2
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  1. #21
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    Part of the problem is....there is no definition of tolerances. If the bolt pattern needs to be accurate enough to hold a wheel/tire at 150MPH, it had best not be done with the dials. But since the OP is re-purposing the hub, it could well be to hold something that doesn't care about runout.

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    Having an existing wheel you might make a center punch that fits the holes out of drill-rod so you can harden it, clamp the assembly so parts can not move, and punch around.

    You might punch and finish one hole and put a nut on it so the rest will be locked on location.

    You might cross-finish two holes and bolt those, then do the rest.

    Drills can drill off location so indexing the part even accurately, then depending on the drill to locate may be a mistake. A center drill or spot drill can be better.

    Take care if made of cast iron or cast steel because a hard hammer whack can beak those,

    A hack method would be to measure a diameter and multiply by Pi,(3.14159) divide that by the number of holes, then make a flexible shim, set and scribe to the shim on the part diameter, This for about +- .005 to .010 if you are careful. Yes turning the part to an eyeball finger locator.

    If getting back to the first scribe line and hitting on the mark then you did an Ok job of ot.

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    And DON'T forget about BACKLASH on the hand cranks. :-)
    ...lewie...

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    Quote Originally Posted by plastikdreams View Post
    That's pretty cool, we make parts for p&w engines.

    New Jersey was the home of Wright Aeronautical - P&WA's main competition 80 years ago

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    Quote Originally Posted by Marc1122 View Post
    I am working on an antique car hub I had to weld the stud holes closed and turn it down for a new application. I need to drill a new bolt circle but am not sure how to do it since it is not a flat piece. I have a milk but no DRO. Thanks for any input
    THIS is when you outsource it to someone who has the right tools, not every tool is a hammer, and not every screwdriver is a hammer either.

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    Re; I have a milk but no DRO.

    You can make homemade plastic out of Milk..but the is a whole another subject so would need a different thread title.

    I know you meant Mill, just kidding.

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    Quote Originally Posted by BT Fabrication View Post
    THIS is when you outsource it to someone who has the right tools, not every tool is a hammer, and not every screwdriver is a hammer either.
    The old millwright joke.

    Millwright guy goes to the tool crib and asks "I need a really big wrench.
    'What size?
    just big.
    how can you use a wrench if you don't know the size?
    Because I'm not going to use it for a wrench, I'm going to use it for a hammer.

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    Quote Originally Posted by Dan from Oakland View Post
    If you don't have a rotary table, calculate each hole center, find the center of your hub and use those dial things on the machine to move to each hole center and drill/bore the new holes. Millions of parts have been made on machines with no DRO. If you struggle with finding the hole centers, I'm sure there is a bolt circle calculator out on the web somewhere.
    Bolt circle calculator

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    Quote Originally Posted by GregSY View Post
    ... since the OP is re-purposing the hub, it could well be to hold something that doesn't care about runout.
    Bolts shouldn't determine the location. Not saying they don't 'cuz we haven't seen the part but not supposed to.

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    wheel bolts very often do.

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    In the way back days no mills had DROs.
    You also learned to eliminate lash and approach all numbers on the dials from the same direction.
    Even a old mill with .050 lash should get you within .003 true position which is probably better than the tolerances on the bolts themselves.
    Bob

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    Quote Originally Posted by EmanuelGoldstein View Post
    Bolts shouldn't determine the location. Not saying they don't 'cuz we haven't seen the part but not supposed to.
    Confused here. I thought centering off the hub and wheel hole went away a fair bit back.
    Bob

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    Quote Originally Posted by CarbideBob View Post
    Confused here. I thought centering off the hub and wheel hole went away a fair bit back. Bob
    Just depends on what you've got. There are still a lot of applications with flanged bolts/nuts where the centering is all on the center hole. With tapered bolts/nuts it can go either way, or a combination of the two. I HATE it when some dimpledick puts on a wheel with too big a hole and I have to hoist the thing up to get the lug bolts in, especially on heavier truck tires. Not quite so bad with fixed studs and nuts.

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    All the vehicles in my family still have a piloted hub. That's two BMWs, 2007 and 2015; 2013 and 2017 Fords; a 90's Honda... I didn't know there were any passenger vehicles that didn't center on a piloted hub.

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    Quote Originally Posted by eKretz View Post
    . . .I didn't know there were any passenger vehicles that didn't center on a piloted hub.
    I don't know of any either. The weirdness I see is mostly on small trailers and smaller utility tractors.

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    Quote Originally Posted by Gordon Heaton View Post
    I don't know of any either. The weirdness I see is mostly on small trailers and smaller utility tractors.
    In the aftermarket wheels I deal with (drag racing), we see most of them being lug centric but the original OEM are mostly hub centric. You do have to be a little careful if you are changing things around and don't understand what you got.

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    [QUOTE=GregSY;3789481]No idea what a milk is.







    Now surely you've seen the commercial "got milk?"

    I couldn't resist.

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    Really?

    You must have a very old and worn mill. Even the inexpensive, import mills that we are not supposed to talk about here have screws and therefore dials that are consistent to better than a thousandth.

    Now, don't get me wrong. I am not saying that the screws on these machines are dead accurate. What I am saying is that their errors are consistent enough along their length so that your bolt circle will still be a good circle and if you reference the dial readings to a point at the center of that bolt circle then the resulting bolt circle will be well centered.

    Of course, it goes without saying that backlash must always be taken into account. Every hole location must be approached from the same directions to arrive at the calculated coordinates with the dials. But then, indexing heads and rotary tables also have those same backlash considerations.

    Yes, DROs are wonderful to have but the OP does not have one.

    And then, there is the fact that mounted tires, even ones intended for normal highway speeds, are routinely balanced when they are mounted. I certainly would not use one at 150 MPH without it being balanced first. And I suspect that no driver that goes that fast would.



    Quote Originally Posted by GregSY View Post
    Part of the problem is....there is no definition of tolerances. If the bolt pattern needs to be accurate enough to hold a wheel/tire at 150MPH, it had best not be done with the dials. But since the OP is re-purposing the hub, it could well be to hold something that doesn't care about runout.

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    I have run mills that had considerable slop in the long and cross travel, enough to make a poor job of a bolt circle and incremental spacing. A set of point dividers and by careful hand layout would/could get closer than .010.

    Just .005 or .010 lead screw long and cross slop would make a close hole pattern off the dials near impossible.

    Likely any good condition wheel with just the same number of holes could be centered and use for a template for index, not diameter. still, the holes might be good enough / but not to the manufacturer's specifications.

    I agree that most wheels have a center hub that locates the wheel center and that .010 hole spacing might not be a big deal..except that it would stress the wheel perhaps to the point of cracking the wheel.

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    Most OEM wheel are hub-centric, but most aftermarket wheels are not. The simple fact is that with an accurate hole pattern (usually attributed to 'CNC machining'), the bolt pattern will hold a wheel on center quite well.

    Then....I've owned a few hub-centric Ford vehicles where they install the wheel over a raw steel hub on the assembly line. The fit is tight, and rust occurs, and after a couple years you have to beat the wheel off the hub. This also happens with the brake drum/rotor quite a bit. There are plenty of YOutube videos showing tricks to pry rotors off hubs.

    I've made a few welding rotary tables using trailer wheel hubs....bolt the spindle to the bug welding table, and make a flat platform that spins (by hand). The ROM is 1 or 2. The point being, the wheel hub might not have any need for concentricity within 1/4" or so.


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