I'm making a new set of con rods for a 2 cyl steam engine because there was
a slight rod knock on one crank and no way to adjust for it. I visualize
split bearings on the crank pin ends. The rods are made of brass and I'd
like to put in "bearing" bronze inserts on the crank ends. The bronze
insert disks will be "lock-tited" in place before splitting off the caps.
Then, the holes will be opened, reamed and lapped to fit the crank journals
which are 5/16 drill rod. Does anyone see a problem with this approach?

Bob Swinney

Robert Swinney wrote:

I'm making a new set of con rods for a 2 cyl steam engine because there was
a slight rod knock on one crank and no way to adjust for it. I visualize
split bearings on the crank pin ends. The rods are made of brass and I'd
like to put in "bearing" bronze inserts on the crank ends. The bronze
insert disks will be "lock-tited" in place before splitting off the caps.
Then, the holes will be opened, reamed and lapped to fit the crank journals
which are 5/16 drill rod. Does anyone see a problem with this approach?

Bob Swinney


I'd be concerned about a glued joint holding up to the splitting and
post-splitting machining process. I think I'd be more inclined to use
silver (or even plain ol' lead) solder.

I'd also be tempted to make the whole cap out of bearing bronze, and
only insert the rod, or just be happy with the brass-steel mating surface.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim sez:
I'd be concerned about a glued joint holding up to the splitting and
post-splitting machining process. I think I'd be more inclined to use
silver (or even plain ol' lead) solder

Who said anything about a "glued joint"? Split bearing caps are always held
in place by bolts. Perhaps, I wasn't clear. It should be understood the
insert (discs) would be lock-tited in place and the cap bolts installed,
before drilling, reaming and lapping the holes. Silver solder would work as
well, but why bother? The bearing hole is lapped to fit the crank journal -
after splitting.

Bob Swinney


"Tim Wescott" wrote in message
...
Robert Swinney wrote:

I'm making a new set of con rods for a 2 cyl steam engine because there
was a slight rod knock on one crank and no way to adjust for it. I
visualize split bearings on the crank pin ends. The rods are made of
brass and I'd like to put in "bearing" bronze inserts on the crank ends.
The bronze insert disks will be "lock-tited" in place before splitting
off the caps. Then, the holes will be opened, reamed and lapped to fit
the crank journals which are 5/16 drill rod. Does anyone see a problem
with this approach?

Bob Swinney

I'd also be tempted to make the whole cap out of bearing bronze, and only
insert the rod, or just be happy with the brass-steel mating surface.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Robert Swinney wrote:

Tim sez:

I'd be concerned about a glued joint holding up to the splitting and
post-splitting machining process. I think I'd be more inclined to use
silver (or even plain ol' lead) solder


Who said anything about a "glued joint"? Split bearing caps are always held
in place by bolts. Perhaps, I wasn't clear. It should be understood the
insert (discs) would be lock-tited in place and the cap bolts installed,
before drilling, reaming and lapping the holes. Silver solder would work as
well, but why bother? The bearing hole is lapped to fit the crank journal -
after splitting.

Bob Swinney

I was confused about your order of operations, I think.

I think I thought that you were going to drill a hole in the con-rod
blank, glue in your bronze disk, drill your con-rod bolt holes, tap,
split, machine (across the glued half-disk), bolt it together, drill the
glued half-disks, ream, etc. Somewhere in this envisioned process I saw
the inserts coming unglued.

How are you going to hold the inserts in place while you do all your
machining?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Tim sez: "How are you going to hold the inserts in place while you do all
your
machining?"

Sorry about the confusion. Here's how it goes:

1. Bore insert hole in the con rod end at the proposed bearing center line.
Insert diameter maybe 50% greater than bearing hole.
2. Locktite insert disc in hole.
3. Drill and tap 2 holes, lengthwise, for cap bolts.
4. Split at bearing centerline location..
5. Install cap bolts.
6. Drill, ream, lap, the bearing hole.
7. Open bearing by removing cap bolts.
8. Install split bearing on crank pin with cap bolts.

As per usual, anything "intuitive", always has more steps than is foreseen
in the beginning. I think, maybe, in full size practice there would be 1 or
2 shims placed at the split line before opening the bearing hole. As wear
occurred, a shim would be removed to close up the bearing hole. This might
lead to a slightly elliptical hole but it would take up the wear. Some con
rod bearings were adjusted with a wedge shaped key driven against the split.

Bob Swinney


"Tim Wescott" wrote in message
...
Robert Swinney wrote:

Tim sez:

I'd be concerned about a glued joint holding up to the splitting and
post-splitting machining process. I think I'd be more inclined to use
silver (or even plain ol' lead) solder


Who said anything about a "glued joint"? Split bearing caps are always
held in place by bolts. Perhaps, I wasn't clear. It should be
understood the insert (discs) would be lock-tited in place and the cap
bolts installed, before drilling, reaming and lapping the holes. Silver
solder would work as well, but why bother? The bearing hole is lapped to
fit the crank journal - after splitting.

Bob Swinney

I was confused about your order of operations, I think.

I think I thought that you were going to drill a hole in the con-rod
blank, glue in your bronze disk, drill your con-rod bolt holes, tap,
split, machine (across the glued half-disk), bolt it together, drill the
glued half-disks, ream, etc. Somewhere in this envisioned process I saw
the inserts coming unglued.


--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Robert Swinney wrote:

Tim sez: "How are you going to hold the inserts in place while you do all
your

machining?"


Sorry about the confusion. Here's how it goes:

1. Bore insert hole in the con rod end at the proposed bearing center line.
Insert diameter maybe 50% greater than bearing hole.
2. Locktite insert disc in hole.
3. Drill and tap 2 holes, lengthwise, for cap bolts.
4. Split at bearing centerline location..
5. Install cap bolts.
6. Drill, ream, lap, the bearing hole.
7. Open bearing by removing cap bolts.
8. Install split bearing on crank pin with cap bolts.

As per usual, anything "intuitive", always has more steps than is foreseen
in the beginning. I think, maybe, in full size practice there would be 1 or
2 shims placed at the split line before opening the bearing hole. As wear
occurred, a shim would be removed to close up the bearing hole. This might
lead to a slightly elliptical hole but it would take up the wear. Some con
rod bearings were adjusted with a wedge shaped key driven against the split.

Bob Swinney

That is the order of operations that I would contemplate -- do you
really think the glue will hold? I won't say it'll fail -- gluing metal
seems to be a perfected art, it just goes straight across the grain for me.

I think in automotive applications they resize bottom end bearings by
shaving a bit off of the interface between cap & rod, then boring the
hole out round. This is probably not necessary in a old-style
stationary steam application, because the working speeds are so much less.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Robert Swinney wrote:

It should be understood the insert (discs) would be lock-tited in place
and the cap bolts installed, before drilling, reaming and lapping the
holes.

Be aware, that brass/copper-alloys aren't that good to locktite in. I
would soft solder the bushing into the rod, then cut the cap and ream
the hole.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Thanks, Nick. That is worth considering. I've done it successfully before
with locktite, but silver-bearing solder would certainly be stronger.
Regular soft solder would be ok, too. I've never heard anything about Cu
alloys being a loctkite problem.

Bob Swinney
""Nick Müller"" wrote in message
...
Robert Swinney wrote:

It should be understood the insert (discs) would be lock-tited in place
and the cap bolts installed, before drilling, reaming and lapping the
holes.

Be aware, that brass/copper-alloys aren't that good to locktite in. I
would soft solder the bushing into the rod, then cut the cap and ream
the hole.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Robert Swinney wrote:

I've never heard anything about Cu alloys being a loctkite problem.

That's an official answer I got from LockTite when I had problems with
brass.

Nick
--
Motor Modelle // Engine Models
http://www.motor-manufaktur.de
DIY-DRO - YADRO - Eigenbau-Digitalanzeige

Do not know what the load on your bearing will be. In automotive rods
sometimes the cap has a dowel pin pressed in and the bearing is drilled
to fit over it and stop it from spinning.
Stan

Robert Swinney wrote:

I'm making a new set of con rods for a 2 cyl steam engine because there was
a slight rod knock on one crank and no way to adjust for it. I visualize
split bearings on the crank pin ends. The rods are made of brass and I'd
like to put in "bearing" bronze inserts on the crank ends. The bronze
insert disks will be "lock-tited" in place before splitting off the caps.
Then, the holes will be opened, reamed and lapped to fit the crank journals
which are 5/16 drill rod. Does anyone see a problem with this approach?

Bob Swinney

The load on 3/8" crank pins in a 2 cylinder steam engine is what? High
compared to a watch bearing; low compared to an automotive rod. Spare me
the misery of actually calculating the bearing load. Mostly, the engine
will be run, unloaded at demo speed. I figure it would be capable of 1/4
HP of work if pressured up to 56 psi and turning 500 rpm. It would be
impossible for the inserts to "spin" because the bearing cap screws would
partially cut in to the outer edge of the inserts.

Bob Swinney
"Stan Weiss" wrote in message
...
Do not know what the load on your bearing will be. In automotive rods
sometimes the cap has a dowel pin pressed in and the bearing is drilled
to fit over it and stop it from spinning.
Stan

Robert Swinney wrote:

I'm making a new set of con rods for a 2 cyl steam engine because there
was
a slight rod knock on one crank and no way to adjust for it. I visualize
split bearings on the crank pin ends. The rods are made of brass and I'd
like to put in "bearing" bronze inserts on the crank ends. The bronze
insert disks will be "lock-tited" in place before splitting off the caps.
Then, the holes will be opened, reamed and lapped to fit the crank
journals
which are 5/16 drill rod. Does anyone see a problem with this approach?

Bob Swinney

"Robert Swinney" wrote in message
. ..
I'm making a new set of con rods for a 2 cyl steam engine because there
was a slight rod knock on one crank and no way to adjust for it. I
visualize split bearings on the crank pin ends. The rods are made of
brass and I'd like to put in "bearing" bronze inserts on the crank ends.
The bronze insert disks will be "lock-tited" in place before splitting off
the caps. Then, the holes will be opened, reamed and lapped to fit the
crank journals which are 5/16 drill rod. Does anyone see a problem with
this approach?

Bob Swinney

I question the need for bearing inserts too. Just build the rod as you
describe with the removable cap, bore it to size and run it! A drop of oil
for lube will run a long time on a brass rod, hard steel pin. if it gets
loose, split the rod and file the cap to fit and run it some more. It does
not sound like a critical item, no offence, just a toy!
One shop I worked at had an old turret lathe with an idler pulley on the
belt. The ball bearing died in the pulley one day and I machined one out of
a chunk of brass, and used a hard shoulder bolt for the shaft. We would give
it a drop of oil at shut down in the afternoon and run it eight hours a day.
It was still in use five years later, probably still is today!
Greg

Yeah, I could dispense with the inserts I know; but I kind of wanted the
experience of making them. Besides, as you said (bite your tongue, though)
it is only a toy.

Bob Swinney
"Greg O" wrote in message
...

"Robert Swinney" wrote in message
. ..
I'm making a new set of con rods for a 2 cyl steam engine because there
was a slight rod knock on one crank and no way to adjust for it. I
visualize split bearings on the crank pin ends. The rods are made of
brass and I'd like to put in "bearing" bronze inserts on the crank ends.
The bronze insert disks will be "lock-tited" in place before splitting
off the caps. Then, the holes will be opened, reamed and lapped to fit
the crank journals which are 5/16 drill rod. Does anyone see a problem
with this approach?

Bob Swinney

I question the need for bearing inserts too. Just build the rod as you
describe with the removable cap, bore it to size and run it! A drop of oil
for lube will run a long time on a brass rod, hard steel pin. if it gets
loose, split the rod and file the cap to fit and run it some more. It does
not sound like a critical item, no offence, just a toy!
One shop I worked at had an old turret lathe with an idler pulley on the
belt. The ball bearing died in the pulley one day and I machined one out
of a chunk of brass, and used a hard shoulder bolt for the shaft. We would
give it a drop of oil at shut down in the afternoon and run it eight hours
a day. It was still in use five years later, probably still is today!
Greg