[modeleng] Re: sprockets
- From: "Terry Lane" <tel@xxxxxxxxxxx>
- To: <modeleng@xxxxxxxxxxxxx>
- Date: Tue, 31 Aug 2004 19:21:47 +1000
That would be too easy Jeff. Actually I had a look & the biggest 1/4" pitch
sprocket my supplier lists is 125t - fair way short of the 240 odd teeth I
need
> Hi TEL,
>
> If there is a paying customer, I'd order the sprockets from a power
> transmission supplier like Browning. Hell of a lot of work to make them
from
> scratch from stock plate.
>
> Good luck, Jeff Dayman Waterloo Ontario Canada
>
>
>
> ----- Original Message -----
> From: "Terry Lane" <tel@xxxxxxxxxxx>
> To: <modeleng@xxxxxxxxxxxxx>
> Sent: Monday, August 30, 2004 4:07 PM
> Subject: [modeleng] Re: sprockets
>
>
> > Thanks Richard - yes, the diameter is a bit flexible & that would be big
> > enough. To make the problem a little clearer (?) this wheel is wanted
for
> > the drive system under a HO scale canal. One big sprocket at one end
under
> > the turning pool, two smaller ones at the other - ditto, & a couple of
> idler
> > wheels to hold everything in shape (coming down the narrow central canal
> > section) The chain carries a series of rare earth magnets that pull the
> > barges along thru' the water.
> >
> > We did have the whole system operating on cable drive with MDF pulleys
(on
> > spring arms for tensioning) but the customer wants to revert to his
> original
> > concept of chain drive.
> >
> > Once we get all this sorted it's back to getting the working lock to do
> just
> > that (work). And they wonder why men drink????
> >
> >
> > > Hi Terry,
> > >
> > > In imperial figures, 240 holes on 19.105" pcd will be exactly
.250"
> > > apart. This is only a 486.41 mm pcd, but you did say approx 500 and
240
> > > holes at 1.500 degrees sounds a lot easier to me, not that I fancy
> having
> > to
> > > drill them.
> > >
> > > ----- Original Message -----
> > > From: "Terry Lane" <tel@xxxxxxxxxxx>
> > > To: <modeleng@xxxxxxxxxxxxx>
> > > Sent: Monday, August 30, 2004 11:45 AM
> > > Subject: [modeleng] Re: sprockets
> > >
> > >
> > > > Thanks Rich - now where did I put that 247 tooth gear wheel to index
> it
> > > > with?
> > > >
> > > >
> > > > > Hi there Terry,
> > > > >
> > > > > I'd suggest the following (hoping my maths is correct):-
> > > > >
> > > > > Guess the number of holes - a good estimate would be to say that
the
> > > > > circumference of your 500mm sprocket is about pi*500mm, which is
> > 1571mm,
> > > > > and your pitch is 1/4"=6.35mm, which goes into the circumference
> about
> > > 247
> > > > > times.
> > > > >
> > > > > Divide 360 degrees with that number - leaving 1.4575 degrees.
> > > > >
> > > > > Now draw out a right angled triangle in front of you, with one
angle
> > > very
> > > > > small.
> > > > >
> > > > > Assume that this small angle is half of the 1.4575 degrees (0.7287
> > > > > degrees), and that the side opposite this angle is half of your
> pitch
> > > > > (1/8"=3.175mm).
> > > > >
> > > > > The hypotenuse of the triangle should not be the RADIUS that you
> > should
> > > > > form the holes on for your sprocket for 495 teeth:-
> > > > >
> > > > > hole radius= 3.175mm/ sin 0.7287degrees = 249.633mm
> > > > >
> > > > > giving a diameter for your holes to lie on of 499.267mm.
> > > > >
> > > > > This doesn't allow for any clearance between the chain rollers and
> the
> > > > > sprocket though.
> > > > >
> > > > > Hope this is of some use.
> > > > >
> > > > >
> > > > > Yours,
> > > > >
> > > > >
> > > > > Rich.
> > > > > PS 247 HOLES!!! OUCH!
> > > > >
> > > > > On Mon, 30 Aug 2004, Terry Lane wrote:
> > > > >
> > > > > > I'm sure the info is somewhere but - have any of you got a quick
> way
> > > of
> > > > > > calculating sprocket cutting. I got a job here that calls for a
> > > sprocket
> > > > > > aprox 500mm diameter to drive 1/4" pitch chain. Now OK - the
teeth
> > > gotta
> > > > be
> > > > > > one pitch apart, & the holes gotta be pin dia.+?, but how do I
> > arrive
> > > at
> > > > a
> > > > > > pitch circle for the ring of holes?
> > > > > >
> > > > > >
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