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Posted by R. Zimmerman on May 3, 2006, 8:31 pm
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I would try something like an extra one eighth rib on the outside rim. It
is only four inches in diameter so that should do it. It will locate your
weld closer to the neutral axis of the disc.
I agree with one comment about overwelding. Can you shrink the assembly
on and just put a couple of locating tacks in???
I worked for a company that build wheels for ore trucks. Their original
design called for simply shrinking the rim onto the steel centerpiece. No
weld was required at all. Later designs had just a little bead to locate
the rim on the centerpiece. These were big wheels handling hundreds of tons
payload.
Your solution will end up being the combination of all the contributions
here.
Yes you are right about letting your assembly cool after welding. Warm to
the touch is OK.
Randy
>snip<
I could add some ribs to the flange, but I would have to start out with
a thicker piece and take off a lot of material. How tall and how many
ribs would you recommend for an 1/8" thick flange. It is about 4"
diameter with a 1 1/8 center bore.
I don't have the option to weld first and then machine. My mill does
not have the Z travel to accomodate my hub.
Before I begin machining a new hub I will try the old hammer and dial
indicator trick to see if I can true up my flanges. Maybe I'll get
lucky this time! Thanks.
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Posted by Terry on May 5, 2006, 2:43 pm
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I like the idea of shrinking the flange onto the tube. I can easily
machine the flange I.D. to be a couple of thousands smaller than the
tube O.D. Then I could use a hotplate to heat up the flange then slip
it into place and let cool. I could then put some very small tack
welds in place.
How much undersized would you recommend making the flange I.D. compared
to the tube O.D. for a permanent fit with no chance of slippage?
If I can't true up my existing assembly, I will go this route on the
next one. Thanks.
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Posted by RoyJ on May 5, 2006, 10:51 pm
Please log in for more thread options For steel the coefficient of linear expansion is about 12 x 10e-6 per
degree C. Figure the max temp difference you can achieve while
assembling the worst case fit (oversized shaft tolerance with undersized
hub tolerance. If you put a 1" shaft in some liquid nitogen at -196C and
heat the hub to the max your home oven will go (say 270C) you will get
.0055" of total expansion/shrinkage. The max interferance fit you can
get in practice has a lot to do with how accurate your machining is plus
how well you can assemble the parts before they start normalizing their
temps.
We did one aluminum prototype in two pieces that was supposed to have
.002" clearance with the temps we were using. We wound up using a press
to assemble since the aluminum conducted the heat so fast. But the parts
were bonded together1
Cheers.
Terry wrote:
> I like the idea of shrinking the flange onto the tube. I can easily
> machine the flange I.D. to be a couple of thousands smaller than the
> tube O.D. Then I could use a hotplate to heat up the flange then slip
> it into place and let cool. I could then put some very small tack
> welds in place.
>
> How much undersized would you recommend making the flange I.D. compared
> to the tube O.D. for a permanent fit with no chance of slippage?
>
> If I can't true up my existing assembly, I will go this route on the
> next one. Thanks.
>
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Posted by dave on May 6, 2006, 9:57 am
Please log in for more thread options idea:
cut slight taper on part to be inserted (less than a morse taper, like a
degree, or maybe even half a degree), with matching taper in the axle
end. freeze spindles, heat outer tube, slam together "pronto-like" (wood
block, vice, huge hammer). bonded forever, no welding, no add'l fasteners.
reamers -might- be available in sizes correct for the outer tube, to
simplify things...
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Posted by RoyJ on May 6, 2006, 10:52 am
Please log in for more thread options Using a taper will work but makes it very tough to get the longitudinal
position correct.
dave wrote:
> idea:
>
> cut slight taper on part to be inserted (less than a morse taper, like a
> degree, or maybe even half a degree), with matching taper in the axle
> end. freeze spindles, heat outer tube, slam together "pronto-like" (wood
> block, vice, huge hammer). bonded forever, no welding, no add'l fasteners.
>
> reamers -might- be available in sizes correct for the outer tube, to
> simplify things...
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