Re: Mystery tool

On Dec 27, 6:41 pm, M-gineering <ikmotgeens...@xxxxxxxxxxxxxx> wrote:
unforgive...@xxxxxxxx wrote:
On Dec 27, 9:40 am, dabac <dabac.329...@no-
mx.forums.cyclingforums.com> wrote:
carlfo...@xxxxxxxxxxx Wrote:

No, it's not a trivet:
http://i10.tinypic.com/6x7defb.jpg
It's a tool used in the manufacture of bicycles.
I know what it's called. but only because I stumbled over the picture.
I'm still not sure exactly what the hell it does.
I can't say I'm 100% certain, and I certainly don't know the name in
English. But it has a striking resemblance to a stock item in mechanical
workshops before the CNC-machine became commonplace.
A direct translation from Swedish would be "division bell" and it was
used for getting the spacing right when cutting gears and sprockets

Imagine a soon-to-be chainwheel blank put on the perforated plate, and
the holes then used to show what material to remove, and what to leave.
I imagine that'd leave you with something quite similar to those
"every-2nd-link-engagement" chainwheels often found on the old bike pics
you post links to every now and then.

--
dabac

That make sense, except that there are about 40 slots in the outside
row.  Engaging every other link, that would be a huge chain ring.  It
also doesn't explain the extendable arms.  I'm going to guess that the
perforations are a red herring and that this has something to do with
drilling or profiling rims.  Assuming that the tag off to the left is
about an inch wide, it's about the right size.  The big wing nut in
the center extends the arms out evenly and the ends grip onto the
inside of a rim blank.  The shaft coming in from the right is going
into a bell housing, which means that the entire assembly on the top
probably rotates.  Without seeing it from different angles it's hard
to tell if it turns continuously (holding the tire side of the rim up
to a profile cutter) or has stops (for drilling holes at intervals).
From the small size of the mounting brackets on the bottom I would
lean toward drilling.  I could envision something like this bolted
onto the carriage of a lathe with a spoke hole sized drill bit in the
chuck.

the slotted disk has 5 circles of 40, 36, 32, 28 and 24 holes which you
can presumably engage with the lever on the right. Must be a clue ;)

--
/Marten

info(apestaartje)m-gineering(punt)nl

Does it punch or drill? Is it self-contained/complete?

Joseph
.

Relevant Pages

  • Re: Mystery tool
    ... the holes then used to show what material to remove, ... drilling or profiling rims. ... inside of a rim blank. ... to a profile cutter) or has stops (for drilling holes at intervals). ...
    (rec.bicycles.tech)
  • Re: Mystery tool
    ... On Dec 27, 9:40 am, dabac <dabac.329...@no- ... the holes then used to show what material to remove, ... inside of a rim blank. ... to a profile cutter) or has stops (for drilling holes at intervals). ...
    (rec.bicycles.tech)
  • Re: Scamdium strikes again!
    ... limit describes the stress level to survive an arbitrary number of stress ... believe that holes in rims are a one step process. ... Bicycle rim holes should be finished with a grommet so ... as exfoliation of the Al2O3 in flakes. ...
    (rec.bicycles.tech)
  • Re: Etched rim for TDF braking in rain?
    ... holes drilled in between spoke holes, ... someone tell me about the half-holes between the spoke holes. ... we mean that a standard 135 degree drill bit was used to drill down into the face of the rim on the tire side. ... Dimples could reduce weight a little, ...
    (rec.bicycles.tech)
  • Re: Too many spokes
    ... number of holes weakens the rim. ... Equally, where the spoke count is low, the rim has been designed to ... Common range for that kind of wheel would be 28, ...
    (rec.bicycles.tech)