I am in the process of rebuilding (not enough to restore) an old
Harley . I'm quite sure the steel races in the crankcase halves will
need a touch-up . My manuals and books tell me this is best done with a
piloted lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like
known 4140)steel , which I would like to use for this project . I'm not
planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

On Jan 23, 8:12 pm, Terry Coombs wrote:
I am in the process of rebuilding (not enough to restore) an old
Harley . I'm quite sure the steel races in the crankcase halves will
need a touch-up . My manuals and books tell me this is best done with a
piloted lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like
known 4140)steel , which I would like to use for this project . I'm not
planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

Snag,
Depending on the lapping compound, the lap should always be softer
than the material being finished to size. Some lapping compounds
break down, but don't expect it. I would use brass, it machines much
better than 4140, so you should get a better final bore.
Dave

"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not planning
on hardening anything but the lap itself , and that's my question - Should
the lap itself be hardened ? Should it be made of a softer metal , such as
brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

Laps should be soft enough to hold the grit, and softer than the metal
you're lapping. What they don't often tell you is that the lap also should
be gummy, which goes hand-in-hand with holding the grit firmly. In general,
you want the lap to be somewhat softer than the material being lapped but
not greatly softer. In other words, don't use a lead lap on hardened steel.

Gummy laps are lead, aluminum, annealed copper, annealed brass, and
dead-soft annealed steel. Not 4140. But you could make a fancy expanding lap
"core" out of whatever decent steel you have on hand, and cover it with a
tube or sheet of softer lap material. In fact, some commercial laps have
been made this way in the past. You have to key the lap material somehow to
keep it from slipping on the core.

You may also want to consider using plastic-backed (usually polyester)
lapping film. It's very efficient and it cuts very consistently. If you do
that, make a hard lap and clamp the edge of the film in place in a split on
the lap.

--
Ed Huntress

Why not change from the old needle bearings to new tapered roller
bearings? This is a conversion that most builders do to old harley cases.

cheers
T.Alan


Terry Coombs wrote:
I am in the process of rebuilding (not enough to restore) an old
Harley . I'm quite sure the steel races in the crankcase halves will
need a touch-up . My manuals and books tell me this is best done with a
piloted lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like
known 4140)steel , which I would like to use for this project . I'm not
planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

Ed Huntress wrote:
"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not planning
on hardening anything but the lap itself , and that's my question - Should
the lap itself be hardened ? Should it be made of a softer metal , such as
brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

Laps should be soft enough to hold the grit, and softer than the metal
you're lapping. What they don't often tell you is that the lap also should
be gummy, which goes hand-in-hand with holding the grit firmly. In general,
you want the lap to be somewhat softer than the material being lapped but
not greatly softer. In other words, don't use a lead lap on hardened steel.

Gummy laps are lead, aluminum, annealed copper, annealed brass, and
dead-soft annealed steel. Not 4140. But you could make a fancy expanding lap
"core" out of whatever decent steel you have on hand, and cover it with a
tube or sheet of softer lap material. In fact, some commercial laps have
been made this way in the past. You have to key the lap material somehow to
keep it from slipping on the core.

You may also want to consider using plastic-backed (usually polyester)
lapping film. It's very efficient and it cuts very consistently. If you do
that, make a hard lap and clamp the edge of the film in place in a split on
the lap.

--
Ed Huntress


Ooohhh , I like that idea ! I was considering using some wet/dry
sanding paper , 600 grit or finer as a cutting medium , but a machinist
friend thought that it would "thread" the race . FWIW I did use
sandpaper wrapped on a socket to final size a cluster gear race and it
worked all right .
I'm not even certain yet they need to be lapped , just trying to be
ready if they do ...
Thanks Ed !
Snag

T.Alan Kraus wrote:
Why not change from the old needle bearings to new tapered roller
bearings? This is a conversion that most builders do to old harley cases.

cheers
T.Alan


Terry Coombs wrote:
I am in the process of rebuilding (not enough to restore) an old
Harley . I'm quite sure the steel races in the crankcase halves will
need a touch-up . My manuals and books tell me this is best done with
a piloted lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a
matching taper on a one piece mandrel/pilot . Adjustment will be via a
nut that forces the sleeve (lap) up the taper . The pictures in the
book have angled slots , criss-crossing around the diameter , which I
assume carry the lapping compound . The lap will be kept from rotating
on the mandrel by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like
known 4140)steel , which I would like to use for this project . I'm
not planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

I'm not sure that's possible on a 45 ci flathead ...
Snag

"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not planning
on hardening anything but the lap itself , and that's my question - Should
the lap itself be hardened ? Should it be made of a softer metal , such as
brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

The lap is best made with brass, or bronze. I seem to remember that's what
the factory laps were made from. The ones we had in a motorcycle shop were
expandable, and multifaceted. Shop around, you may be able to buy the
factory tools, or an aftermarket version.

Steve R.



--
Reply address munged to bugger up spammers

Steve R. wrote:
"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not planning
on hardening anything but the lap itself , and that's my question - Should
the lap itself be hardened ? Should it be made of a softer metal , such as
brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

The lap is best made with brass, or bronze. I seem to remember that's what
the factory laps were made from. The ones we had in a motorcycle shop were
expandable, and multifaceted. Shop around, you may be able to buy the
factory tools, or an aftermarket version.

Steve R.



I knew that sooner or later someone that had worked with the factory
stuff would speak up . Thanks for the info on original construction . I
haven't looked too hard for this stuff , the few pieces I priced were ,
umm , outrageous (just looked again , I could spend over 1500 bucks on
just motor tools) . I have the tooling to make this stuff , and there's
no hurry . It's not like I'm depending on a 1939 Harley to get to work .
Heh , just came in from the shed . I finished machining a
transmission mainshaft spacer . Got enough parts and tools out there to
fill more than a few evenings !
But I still need a mill , it would make things so much easier ...
--
Snag

"Steve R." wrote in message
news:nzbmj.3477$4w.1952@pd7urf2no...

"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not
planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag

The lap is best made with brass, or bronze. I seem to remember that's what
the factory laps were made from. The ones we had in a motorcycle shop were
expandable, and multifaceted. Shop around, you may be able to buy the
factory tools, or an aftermarket version.

Steve R.



--
Reply address munged to bugger up spammers

I seem to remember thet original Harley and Indian bearing laps were of cast
iron, at least in the 1940-1950 era. Be sure you have access to suitable
rollers. The original ones were available in 0.0002" step sizes and were
selectively fit after the races were lapped.

Don Young

Don Young wrote:
"Steve R." wrote in message
news:nzbmj.3477$4w.1952@pd7urf2no...
"Terry Coombs" wrote in message
news
I am in the process of rebuilding (not enough to restore) an old Harley
. I'm quite sure the steel races in the crankcase halves will need a
touch-up . My manuals and books tell me this is best done with a piloted
lap , guided by the race in the other half .
I'm thinking a split sleeve , tapered inside and riding on a matching
taper on a one piece mandrel/pilot . Adjustment will be via a nut that
forces the sleeve (lap) up the taper . The pictures in the book have
angled slots , criss-crossing around the diameter , which I assume carry
the lapping compound . The lap will be kept from rotating on the mandrel
by a pin in a slot - opposite the split
I have a big 'ol chunk of 4140 type (sparks and hardens just like known
4140)steel , which I would like to use for this project . I'm not
planning on hardening anything but the lap itself , and that's my
question - Should the lap itself be hardened ? Should it be made of a
softer metal , such as brass or aluminum ?
Feel free to poke holes in my idea ...

Snag
The lap is best made with brass, or bronze. I seem to remember that's what
the factory laps were made from. The ones we had in a motorcycle shop were
expandable, and multifaceted. Shop around, you may be able to buy the
factory tools, or an aftermarket version.

Steve R.



--
Reply address munged to bugger up spammers

I seem to remember that original Harley and Indian bearing laps were of cast
iron, at least in the 1940-1950 era. Be sure you have access to suitable
rollers. The original ones were available in 0.0002" step sizes and were
selectively fit after the races were lapped.

Don Young


And that's what I've just gone thru with the tranny . The rollers for
it are in .0004 steps ... and I had to enlarge the main race a couple of
tenths to get the fit I wanted after a clean-up grind on the lathe .
After the motor is cleaned up and the races checked and lapped if
necessary , I will order the correct size . Already got all new shafts
for the crank assembly , but the motor is waiting for me to finish the
transmission . Motor parts are plentiful and reasonably priced . Not so
for parts that fit a two stud three speed tranny . I've been collecting
stuff for several years . Finally found the money to get that last
couple of bits I needed .
And I'm havin' a blast putting it all back together ! Might take a
couple more years , but I'll eventually get it finished .
--
Snag