PM Research No. 1 Build

[rhitee93]

OK, I am deviating from the plans again. I decided that I would be happier if I built up a crank rather than use the cast one from the kit. I got wrapped up in the work tonight, and forgot to take pics, but here is the connecting rod journal attached to the side plates. (I don't know what the correct name for the parts are ??? )

I wanted the crank to have counterweights because I think it makes the motion more interesting. The journal is pressed into a "D" shaped hole, and then I drilled and pressed in 1/8" pins radially after making some adjustments to get the sides as parallel as possible.

Tomorrow I'll put a 6" piece of drill rod through the center hole, and pin it in place. I plan to spin it on the lathe to see how true it is, and make any cleanup passes that I feel are necessary. Then I'll cut out the center section of the drill rod to finish the crank.

 

[smfr]

That's going to be a great-looking crankshaft. It's fun to see two PM Research builds going on at the moment!

 

[rhitee93]

Thanks! Here are a couple of shots of what it will look like in the end...

 

[rudydubya]

Brian, following with interest. How did you make those "D" shaped holes in the webs? Looks like the journal fits well in them.

Regards,
Rudy

 

[rhitee93]

Rudy, to be honest, I cheated! I have access to an abrasive water jet cutter. The holes were a ligt press for the D-shaped pins.

This evening I put a piece of drill rod through the center hole of the crank, and pinned it in place. Once it was all together, I milled out the piece of shaft in the middle. The idea was that the ends would stay on their original center lines so that everything would run true. It wasn't entirely successful, however. I put one end in a collet in my lathe (Which I know to run true to a couple of tenths) and I get about 6 thou of run out at the opposite end. I suspect it is going to run a bit tight once I bore out the crank bearings, but we will see.

I didn't take as many pics today as I should have. I did remember to snap one when I was setup to cut out the excess shaft in the middle.

 

[Don1966]

Nice work Brian , things are getting closer to completion. Still hanging in watching your progress.

Don

 

[rhitee93]

This was a good day! I got the bearing caps made and fitted to the frame, and then put in the hole for the crank bearing.

I left the two caps attached to each other for most of the machining steps.

Here I am set up to finish the mating surface.

Locating the center:

Finishing up the bottoms:

And finally forming the tennon:

 

[rhitee93]

Next I flipped the part over and clamped on the tennon I just machined so that I could drill the screw holes.

First spot-facing for the bearing cap nuts:

Then spot-drilling:

I know what you are thinking, "He is going to drill into the vise!" Actually, I had set the zero point on the z-axis readout to a place about 0.010" above the vise. That way I could drill most of the hole with the accurate setup in the mill, and finish it up on the drill press.

Here are the mostly drilled holes ready to be finished up at the drill press:

 

[rhitee93]

With all the tools at my disposal, I don't have a vertical metal cutting bandsaw : so here I am separating the two bearing caps with a hacksaw.

Of course, I had to do a quick test fit, but I hadn't tapped the holes in the base yet. I should have done this in the same setup I used to drill the holes, but I didn't have a tap handle that I could hold with the mill spindle yet, and there wasn't enough feel to tap these 3-48 holes when I held the tap in the full sized drill chuck.

To get the holes tapped straight, I drilled a hole in a piece of plastic that was a slip fit for the tap. the plastic was large enough to span both bearing blocks so that I could keep it flat and the tap perpendicular to the holes. (This is an age old tapping trick)

...and the test fit:

 

[rhitee93]

I want to point out another goof. I should have machined these bearing locations first and let them dictate the other surfaces on the base. It has taken some odd setups to make the bearing caps match, but it all worked out in the end.

Here I have the entire base setup in the mill to drill out the bearing holes. I don't have a boring bar that is small enough for a .375" hole yet long enough to reach both bearings so drilling and reaming is my best option.

I also hedged my bet a bit. I have a tendency to make holes too large, so I put a piece of scotch tape between the bearing caps and the stands to act as a shim. This way I can back up a bit if necessary.

I don't care for using successively larger drills, but in this case I spotted the location and started with a smaller drill that was just large enough to allow me to pass a long centerdrill through to spot the second bearing location.

Then I drilled through with a "U" drill and reamed with successive reamers until a test shaft fit the way I wanted. The test shaft was cut from the same piece of drill rod I used to make my crank.

 

[rhitee93]

Here is a test fit of the parts I have to date. It is starting to take shape.

I was worried that my crank may be to misaligned to turn freely, but it seems fine.

I want to get to work on the connecting rod and cross head next...

 

[Don1966]

That is really looking great Brian. You have made look easy, keep the photos coming.

Don

 

[smfr]

Looking good! The reference plate on the base sure makes it easy to get the holes straight. I'm struggling now with a setup on my Stuart No. 4 base, and a reference plate would make it much easier.

 

[rhitee93]

Thanks Simon. I have been watching your #4 build. I would think that your machine base would be suitable as a reference plane to locate your bearings.

The reference plate makes it easy to clamp up the part, but if that is what you need, can you still add the plate?

 

[rhitee93]

OK, I have been a bit tied up the last few days, but I finally got back to working on the engine after work today.

Since I have the crank ready to go, I have been chomping at the bit to get the con rod started. It is a pretty awkward part, however, and I spent some time twiddling the casting around in my hand thinking of ways to fixture it.

The trick is to find a way to saw cut the bearing cap from the rest of the con rod, but put it all back in the mill so that the saw cut surfaces can be machined back to a common straight line. However, first things first. I had to drill the screw holes for the cap.

Drilling the holes for the bearing cap screws isn't the easiest thing either since the part is so long. As you can see below, I though I could clamp it up in the vise and go slow. I would not recommend this approach! I got away with it, but only barely. I should have taken the time to setup the angle plate!

Here I am gingerly spotfacing the hole locations:

And after spot drilling, I drilled the holes:

Then I sanded/files off the gate to get ready for the sawing step. I just made the saw cut, but that post will have to wait for a bit.

Please enjoy the new larger photos

 

[rhitee93]

I don't have a vertical metal cutting bandsaw, so I cut the bearing cap from the connecting rod using a jeweler's saw. This took some time to do!

Next I set the connecting rod up in this fixture for a few operations. The fixture has an 1/8" pin that slips through a temporary hole drilled/reamed at the wrist pin location. This allows me to locate the main bearing location. In this pic, I am milling off the saw cut face.

Here is the cheesy way that I faced of the bearing cap. I'm not proud, but it worked OK. The shim stock was used to position the cap "Level" so the milled surface would be properly aligned to the mating surface on the connecting rod.

Here the cap is screwed to the rod awaiting the drilling operation. The cellophane tape shim worked well for me on the main bearing caps, so I did it again here. Perhaps some day I'll learn to make my holes 0.002" smaller

 

[Don1966]

Great photos Brian, I love your reference plate looks like it work well for you. You have make great progress so far and still following along with you.

Don

 

[rudydubya]

Like Don said, great pictures Brian. I enjoy seeing how others approach a problem and then ask myself how I would do it. I learn a lot like that. Of course, I forget most of it overnight... Still following with interest.

Rudy

 

[rhitee93]

Thanks Don & Rudy, I am having a ball with this so far, and it is amazing how much you can learn hanging around this place.

In the next shot, I am getting ready to drill the initial hole for the big end bearing. Those of you following along will notice that I have reverted back to using a center drill. Whoever finds my new Spot Drill in the worm-hole under their bench, please throw it back in my direction...

Then I used a "U" drill to create the initial hole.

Followed up with the appropriate reamer.

Then it was just a matter of facing off the big end to fit my crank...

And then going back to drill and ream the wrist pin hole to the correct size. I goofed here. You would think that after 20 years of puttering around in a shop I would stop thinking I can hold a part when I drill a hole through it. I got lucky in this case. The part grabbed, and got flung across the shop but I only bloodied my thumb up a bit. Maybe I'll learn this time :-[

This shot is the second take after I retrieved the rod from under the bench across the shop.

Finally, another test fitting:

 

[smfr]

Excellent progress!

I would probably have kept the conrod in the fixture for drilling both ends; it's fairly critical that the two holes are parallel. That would have required changing the setup a bit, but I think it would have been worth it.

Simon