Winner Pm Research Engine #7

[tomw]

Dataporter, Thank you for following along. I am glad the log has been interesting to date.

Ogler and Brian, thank you both for following along. I actually used my tap to reposition the nuts in the three jaw. Worked slick. Threading (or tapping for making little bolts) a chunk of round stock is a handy idea for re-chucking tiny fasteners.

Oldntired, I hope you enjoy that build. The PMR #3 was my first model after I got my machines. I couldn't make it run until after a did a few more! I think it is a nice model. I ended up naming the Minor Mishap Steam Engine, in honor of the band my wife belongs to, the Minor Mishap Marching Band.

Hawkeye, I hope I don't lead you astray! Have fun with it, and anything I can do to help along the way let me know. Given I have been machining stuff for only 10 months, it is unlikely I can help you more than you can help yourself!

Thank you to all who have been following along. Your wisdom, encouragement, and gentle constructive criticism have been great. Coming from the world of academic science, I have been pleasantly surprised by the gentleness of the constructive criticism.

Again, thanks tons.

Cheers,

Tom

p.s. The whole small nuts and big hands thing...You know what they say about guys with small nuts..Big gloves. Oh, no, it's big hands and small...Ah, whatever; not to be taken too literally, figuratively, or metaphorically.

 

[Sandia]

Tom this is a little off topic, but I like the Packard in your avatar. I am kind of an old car guy as well.

 

[Hawkeye]

What I mean, Tom, is that there are many ways to do any given machining task. Having someone doing the same, or similar, project ahead of you suggests ways of doing things. The individual may choose to do it the same way, or it my cause you to think of a slightly different method. In any case, the write-up will be very helpful.

Besides, I've been out of my shop for a year. Any reminders I can get are worth reading.

 

[tomw]

Bob,

I am not very familiar with trucks. What is that in your avatar.

My avatar is my wife's 38 Packard coupe. She and I bought it for her birthday. Much of the restoration was done at a local shop. They were very open to my being there and participating, which was great (really great since they know cars but I know Packards). My wife and I, and the shop, restored the car to as close to original as we could. As far as I can tell, the interior was already original.

It was a fun project and got me thinking about expanding my skills to machining.

Here is a better view of the entire car:

And the first award she won:

My wife drives the car all over the place, and really loves it.

Cheers,

Tom

 

[tomw]

What I mean, Tom, is that there are many ways to do any given machining task. Having someone doing the same, or similar, project ahead of you suggests ways of doing things. The individual may choose to do it the same way, or it my cause you to think of a slightly different method. In any case, the write-up will be very helpful.

Besides, I've been out of my shop for a year. Any reminders I can get are worth reading.

Hawkeye,

Of course. I really do hope this log is helpful, to you and to others. Thank you again for following along.

Tom

 

[T Bredehoft]

Are these posts too detailed and thus a bit boring?

We live for details like you supply. Keep it up.

I must add: I really enjoy the random non-shop-specific text. Also, your sense of humor.

 

[tomw]

Time for another update. This should be one of a few or less on the cylinder castings.

The drawings for the right cylinder. The left is a mirror image of this.​

I call these the cylinder castings, but really they are the cylinders and steam chest/valve housings combined. They are cast bronze.

The cylinder castings along with my first cylinder sizing gauge. I ended up having to make one a wee bit bigger.​

The first step was to file off the excess flash. I then clamped the casting in a three jaw chuck. These castings seem to have been intentionally designed to make it possible to use a three jaw chuck and have the bore core-hole relatively closely centered on the spindle. I checked to make sure nothing was completely cockeyed by running the lathe and looking down the core hole. If the hole didn't describe the orbit of pluto, and the piece remained firmly gripped, I was happy to proceed.

The cylinder casting mounted in the 3-jaw chuck and ready for some facing excitement. ​

I faced one side until I had a completely flat surface (essentially removing the casting draft plus a bit). I then flipped the casting in the chuck and faced the other side the same amount as on the first side. I then removed the casting, measured it's length, and calculated how much I need to take off from each end to bring things to tolerance. I then re-chucked the casting, removed said amount, flipped it around, and removed said amount again. Thus the length of the casting has been established with the intake boss nicely centered between the two end. This is way more work than necessary.

Both ends of the cylinder casting have been faced and the cylinder is approaching final length.​

This next bit is important: The side that you last faced before the boring operation is the side that will be mounted on the base. This is because the mounting surface and the bore need to be as close to perpendicular as possible. Thus, the cylinder casting operations described above need to be done such that the intake boss will be up when mounted to the base. In other words, the cylinder castings are mirror images of each other.

Anyway, I next bored the cylinder to size-ish. I don't have a 1/2" gauge pin, so I made one. And then I ended up over-boring by .010 on the first cylinder because I'm easily oooh, squirrel. So I made a gauge pin slash future jig bit for the second cylinder and bored to that size. That one came out with the same degree of wrongness as the first.

Boring

Boring

Bored​

Next post will be on getting the valve stuff drilled.

Cheers,

Tom

 

[tomw]

The next step taken was drilling the valve chamber. I took a really complicated route to doing this, which I am going to skip over, and give you the simplified version.

Because of the operation I did in the last post, I have specified which casting is my left versus right cylinders. When mounted to the base, the right casting will have the inlet port towards the left and facing up. For the other cylinder, it is just the opposite. So, I marked the face of the castings that would be against the base. It is from these faces that I will drill the valve bores. Basically the orientation of the cylinder casting needs to match the drawings when drilling these holes. Otherwise one cylinder will be great, but the other will have the inlet ports either on the wrong side of the assembly, or facing down.

If you are stuck in quicksand, digging deeper won't help.

The hole for the valve needs to be 3/4" from the center of the cylinder bore, and in the middle of the conical casting. The first thing I did was put a scribe line on the casting that bisected the conical portion. I did this in the same way I bisected the crank throw, by scale, eye and several punch marks. I then had a casting with a scribed line upon which the valve bore would be drilled.

Still digging...

For some reason, I felt I need to mount the cylinder on a square piece of aluminum stock, and then securing that in my machine vise jaws. I am certain this is unnecessary. The basic operation required is indicating the center of the cylinder bore to the spindle, and then indicating the 3/4" distance along the scribed line to the center of the valve bore. Regardless, the point for the valve bore center was found, center drilled, and then drilled through 5/32". As in previous episodes, this sorta long but small diameter hole was drilled carefully so the drill wouldn't go all wonky. Then the hole was drilled and then reamed 1/4" to a depth of 1", leaving the remaining 1/8" of material with a 5/32" drilled hole. This will later be tapped for the exhaust pipe.

Just a little deeper...

This process was then repeated for the other cylinder, but with the inlet port boss oriented in the opposite direction.

The next step was drilling the inlet ports/passages. I will describe those in the next post. I'm tired after writing all those words. Words that convey stuff, but perhaps no more. Ugh.

I delayed doing the machining of these cylinders because I felt they would be difficult. Then I delayed posting about them because it was going to be hard to explain. The machining was easier.

Have a great weekend.

Cheers,

Tom

 

[tomw]

OK, after thinking for many hours about the cylinders, and the previous post, I realized there is an easier way to do this. If you have a small chuck machine (Sherline, Taig, small Grizzly, etc) you can do the boring, then immediately go to the mill with the part still in the chuck. Mount the chuck with the part in on the mill, find the center of the bore, and off you go. The one important change would be to mount the cylinder casting in the chuck with a small spacer so you don't end up drilling into your chuck.

Again, I apologize for my confused narrative in the post above. If anyone needs clearer information, please let me know.

Cheers,

Tom

 

[Sandia]

Bob,

I am not very familiar with trucks. What is that in your avatar.

My avatar is my wife's 38 Packard coupe. She and I bought it for her birthday. Much of the restoration was done at a local shop. They were very open to my being there and participating, which was great (really great since they know cars but I know Packards). My wife and I, and the shop, restored the car to as close to original as we could. As far as I can tell, the interior was already original.

It was a fun project and got me thinking about expanding my skills to machining.

Here is a better view of the entire car:

View attachment 112032

And the first award she won:

View attachment 112033


My wife drives the car all over the place, and really loves it.

Cheers,

Tom

Nice looking car Tom, I'm sure your wife enjoys driving it. It caught my eye as a friend of mine from San Antonio has one just like it. The picture in my avatar is a 1940 Ford Deluxe Coupe. Picture attached.
PS: I am building the PM Research Red Wing hit and miss engine. Started last winter, but got side tracked during the summer but I plan to get back to it in the next couple of weeks.