I have a question for you more experienced machinist types.
I have a bicycle hub fitted with sealed cartridge ball bearings -
R8-2rs - so 1.125 nominal OD. This is mounted to a 20 inch rim.
I need to remove one bearing and press in a hub/flange for a disc
brake - and possibly in future a drive pulley. The removed bearing
will be installed in the added hub. I am using CRS for the new part.
What kind of interference fit do I need? How much bigger does my shaft
have to be than the hole? Am I best to do a dry fit or dhould I be
using a permanent shaft locker like a green LocTite?
The stub of the hub/flange going into the hole in the hub is 8 mm
(5/16 inches) - the sise of the R8 outer bearing race - and the wheel
will be run on a threaded axle with a spacer between the bearings,
with the wheel hub and the flange/hubconstrained by the axle.
For anyone interested this is to add bicycle disc brakes to my
reproduction 1919 Briggs and Stratton Flyer. The possible drive pulley application would be a 1925 Auto Red Bug.
I am machining the parts on my Myford Super 7 lathe and will be
putting together a rotary table using my myford chuck on my benchtop
drill press to drill the flange for the 6 on 44 mm bolt pattern for
the disc rotor
I have just completed my front steering axles and am working on the "facsimile" motorwheel using a 6:1 reduction 2.5hp (8 cubic inch)
Briggs engine. Looking for a 9 cubic inch to take it's place and also considering making an adjustable timing gear camshaft to advance the
valve timing for more bottom end torque (since I do NOT need the full 3600RPM!!) This would involve machining the gear off one camshaft, and machining the camshaft out of another gear then fitting the machined
recess in the back of the gear over the machined flange on the
camshaft and securing with 2 bolts through elongated holes. to enable splitting the difference between 2 teeth - 44 teath on the cam gear is
just over 8 camshaft degrees or 16.4 crankshaft degrees per tooth and
I require 3 to 7 crankshaft degrees of advance (I estimate) - so
roughly 1/4 to 1/2 a tooth - - -
On 2/23/2023 11:37 AM, Clare Snyder wrote:
I have a question for you more experienced machinist types.
I have a bicycle hub fitted with sealed cartridge ball bearings -
R8-2rs - so 1.125 nominal OD. This is mounted to a 20 inch rim.
I need to remove one bearing and press in a hub/flange for a disc
brake - and possibly in future a drive pulley. The removed bearing
will be installed in the added hub. I am using CRS for the new part.
What kind of interference fit do I need? How much bigger does my shaft
have to be than the hole? Am I best to do a dry fit or dhould I be
using a permanent shaft locker like a green LocTite?
I'd shoot for about a .001 interference fit on the flange to hub fit
. Depending on the thickness of the original bearing bore wall I might
make it as much as .0015 ... and dry fit . If I was using a sleeve
retaining loctite I'd probably go for about .0015+ clearance . That
stuff needs a little film thickness to work right .
The stub of the hub/flange going into the hole in the hub is 8 mm
(5/16 inches) - the sise of the R8 outer bearing race - and the wheel
will be run on a threaded axle with a spacer between the bearings,
with the wheel hub and the flange/hubconstrained by the axle.
For anyone interested this is to add bicycle disc brakes to my
reproduction 1919 Briggs and Stratton Flyer. The possible drive pulley
application would be a 1925 Auto Red Bug.
I am machining the parts on my Myford Super 7 lathe and will be
putting together a rotary table using my myford chuck on my benchtop
drill press to drill the flange for the 6 on 44 mm bolt pattern for
the disc rotor
Set a compass to 22 mm to draw the circle , then step around the
circle with that setting . The chord of a 44 mm diameter circle with six >flats is ... 44 mm (well , pretty close) .
Shipping the gear would likely cost as much as a second used camshaftI have just completed my front steering axles and am working on the
"facsimile" motorwheel using a 6:1 reduction 2.5hp (8 cubic inch)
Briggs engine. Looking for a 9 cubic inch to take it's place and also
considering making an adjustable timing gear camshaft to advance the
valve timing for more bottom end torque (since I do NOT need the full
3600RPM!!) This would involve machining the gear off one camshaft, and
machining the camshaft out of another gear then fitting the machined
recess in the back of the gear over the machined flange on the
camshaft and securing with 2 bolts through elongated holes. to enable
splitting the difference between 2 teeth - 44 teath on the cam gear is
just over 8 camshaft degrees or 16.4 crankshaft degrees per tooth and
I require 3 to 7 crankshaft degrees of advance (I estimate) - so
roughly 1/4 to 1/2 a tooth - - -
If that cam gear is a straight spur gear of either 16 or 20 dp I may
be able to make you a gear so you don't have to burn a second camshaft ...
On Thu, 23 Feb 2023 20:04:30 -0600, Snag <Snag_one@msn.com> wrote:
Set a compass to 22 mm to draw the circle , then step around the
circle with that setting . The chord of a 44 mm diameter circle with six
flats is ... 44 mm (well , pretty close) .
You mean 22mm? - 6 equalateral triangles
"Snag" wrote in message news:ttc206$2fs6e$1@dont-email.me...
On 2/24/2023 9:47 AM, Clare Snyder wrote:
On Thu, 23 Feb 2023 20:04:30 -0600, Snag <Snag_one@msn.com> wrote:
Set a compass to 22 mm to draw the circle , then step around the
circle with that setting . The chord of a 44 mm diameter circle with six >>> flats is ... 44 mm (well , pretty close) .
You mean 22mm? - 6 equalateral triangles
You're right , I don't know why I thought it was a half-circle sweep
per .
Snag
---------------
Despite being mathematically sophisticated in other ways, the ancient Babylonians took Pi as 3 times the diameter, or 6 times the radius as in stepping out the hexagon of equilateral triangles around a circle with a compass.
The Egyptians were closer with Pi = 256/81, or (4/3)^4, but it's less accurate than 22/7. That kills the notion that advanced space aliens
helped them.
https://www.exploratorium.edu/pi/history-of-pi
Perhaps the ancients weren't skilled (or interested) enough to
accurately lay out the scale on a ruler. Greek geometry specifically prohibits markings on the straightedge. Surviving artifacts show that
they were highly skilled at making other things. https://astronomy.com/news/2022/05/a-new-origin-story-for-king-tuts-meteorite-dagger
On Thu, 23 Feb 2023 20:04:30 -0600, Snag <Snag_one@msn.com> wrote:
Set a compass to 22 mm to draw the circle , then step around the
circle with that setting . The chord of a 44 mm diameter circle with six
flats is ... 44 mm (well , pretty close) .
You mean 22mm? - 6 equalateral triangles
For example I've automated the IRS tax
forms, though I file the result from my sister's H&R Block software. For the >last several years my numbers have matched hers.
For example I've automated the IRS tax
forms, though I file the result from my sister's H&R Block software. For
the
last several years my numbers have matched hers.
"Bob La Londe" wrote in message news:tteb9m$2n84i$1@dont-email.me...
I cheat anymore and use an arc chord calculator app on my cell phone
these days. 22mm radius & 60 degree angle. The chord length is 22mm
out to 6 decimal places anyway. Seems the rule of thumb used is pretty
darn good. I'll try to remember that one.
If you are interested:
ArcCalc V1.4
No permissions requested
No mobile data used
No ads
App data does not show an author.
I also use a triangle calculator, but it has in app ads. They are small enough they never interfere though.
Bob La Londe
------------
My personal preference is for apps that use the larger screen on my
laptop or its 19" external monitor, and if I can't find what I want I
write one for practice as a program or spreadsheet. For example I've automated the IRS tax forms, though I file the result from my sister's
H&R Block software. For the last several years my numbers have matched
hers. I'm not mobile enough to benefit from iPhone apps, the (old, free) phone is merely tethered to the (old, $15) laptop for my cellular Internet.
I wrote a spreadsheet to turn half round ball joints for a hoist base
from a dumbbell. The spreadsheet gave the infeed dial setting for each
step along the length, starting at 0 with the tool touching the OD and
end of the blank. The radius and step sizes were constants that I
changed between the coarse roughing and finer finishing passes. When the steps were small enough I filed it smooth.
I have a rotary table and a BS-0 indexer to mill smaller gears and
splines to acceptable angular accuracy. Since my 1950's Clausing mill
lacks a DRO or good safe places to install the scales I lay out larger mounting hole patterns and bolt circles with dividers or a vernier
height gauge, then center punch and match-drill the hole locations. The
holes align well enough as long as I mark one as an index and don't
rotate the parts relative to each other, because drill bits may not
center exactly on pilot holes, and unhardened custom drill bushings wear quickly. Usually manual layout gets me within 0.005". Rolled threads on commercial bolts aren't parallel or concentric enough to the shank to
benefit from closer tolerance anyway. When I was building custom
industrial machinery the components had to be located and aligned on the welded frame by manual methods. As I learned the hard way, jigging the pre-drilled parts in position doesn't overcome weld shrinkage. For some reason my father, an accountant, had a copy of the Audel Millwrights and Mechanics Guide which helped a lot.
Sometimes I find that the device I'm mounting wasn't drilled accurately
in the factory fixture. I had to re-machine a hydraulic pump end plate
with holes that didn't all align with the ones on the other end. I
didn't identify the problem until I had taken it apart and fussed with
it too much to return it, and it was a tempting precision machining challenge. After the repair it's given me 20+ years of service on the
log splitter. That job taught me the limitations of my old milling
machine, such as the quill free play increasing as it extends. I used
the knee feed to bore straight and parallel.
-jsw
At my desk top the CAD software does most of the heavy lifting for me,
and I can always use the lookup tables in the Machinery's Handbook, but
in the back shop I use my cell phone at the machine like some people
used to use their slide rule.
On 2/25/2023 5:35 PM, Jim Wilkins wrote:
"Snag" wrote in message news:ttc206$2fs6e$1@dont-email.me...
On 2/24/2023 9:47 AM, Clare Snyder wrote:
On Thu, 23 Feb 2023 20:04:30 -0600, Snag <Snag_one@msn.com> wrote:
Set a compass to 22 mm to draw the circle , then step around the
circle with that setting . The chord of a 44 mm diameter circle with
six
flats is ... 44 mm (well , pretty close) .
You mean 22mm? - 6 equalateral triangles
You're right , I don't know why I thought it was a half-circle sweep
per .
Snag
---------------
Despite being mathematically sophisticated in other ways, the ancient
Babylonians took Pi as 3 times the diameter, or 6 times the radius as
in stepping out the hexagon of equilateral triangles around a circle
with a compass.
The Egyptians were closer with Pi = 256/81, or (4/3)^4, but it's less
accurate than 22/7. That kills the notion that advanced space aliens
helped them.
https://www.exploratorium.edu/pi/history-of-pi
Perhaps the ancients weren't skilled (or interested) enough to
accurately lay out the scale on a ruler. Greek geometry specifically
prohibits markings on the straightedge. Surviving artifacts show that
they were highly skilled at making other things.
https://astronomy.com/news/2022/05/a-new-origin-story-for-king-tuts-meteorite-dagger
I cheat anymore and use an arc chord calculator app on my cell phone
these days. 22mm radius & 60 degree angle. The chord length is 22mm
out to 6 decimal places anyway. Seems the rule of thumb used is pretty
darn good.
"Bob La Londe" wrote in message news:ttgh71$30usg$1@dont-email.me...
On 2/26/2023 8:07 AM, Jim Wilkins wrote:
......
---------------------
At my desk top the CAD software does most of the heavy lifting for me,
and I can always use the lookup tables in the Machinery's Handbook, but
in the back shop I use my cell phone at the machine like some people
used to use their slide rule.
Bob La Londe
------------------------
That's the difference. You are everywhere, expertly managing your
enterprise,
Even at work I was stashed out of sight in the lab, like Dan Aykroyd at
his boiler room desk in Spies Like Us. At least I was beside the boiler
room instead of in it, and I had a large window to watch the black helicopters parked outside.
Just kidding about the helicopters. They were unmarked white cargo vans equipped to monitor radio signals.
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