PM Research #7 It Begins

[ErichKeane]

Huh... thats interesting! I'm surprised it held! Though, Clickspring has shown some pretty incredible projects with super glue holding stuff!

I just used a bolt through the casting in the area between the slides, then used a machinist-jack to hold it off the table/in place. You might be able to do 2 bolts to the angle-plate, since you have two sets of slides.

 

[Janderso]

You might be able to do 2 bolts to the angle-plate, since you have two sets of slides.

Tom W, did a build thread on this model back in 2015. he hasn't posted since 2018. I sent him a PM.
He clamped his base to an angle plate and used a long center drill to cut the mains.
My concern is getting the base perfectly lined up using irregular surfaces.
Like you said, shims/jack where needed. It's a bit of a puzzle.
I have the angle plates and Kant-Twists. I'm going to work on the base this weekend.
Looking at the base and checking on the surface plate/surface gauge this morning, opposing corners are ground exposing less material that can be seen if looking.
I may try to set it up and mill the bottom of the base. That's the only way I can be certain of a parallel cut with the table (if that makes any sense)
My trick is to get the base equally jacked up and parallel.
Cheers

 

[ErichKeane]

Tom W, did a build thread on this model back in 2015. he hasn't posted since 2018. I sent him a PM.
He clamped his base to an angle plate and used a long center drill to cut the mains.
My concern is getting the base perfectly lined up using irregular surfaces.
Like you said, shims/jack where needed. It's a bit of a puzzle.
I have the angle plates and Kant-Twists. I'm going to work on the base this weekend.
Looking at the base and checking on the surface plate/surface gauge this morning, opposing corners are ground exposing less material that can be seen if looking.
I may try to set it up and mill the bottom of the base. That's the only way I can be certain of a parallel cut with the table (if that makes any sense)
My trick is to get the base equally jacked up and parallel.
Cheers

You might consider your order-of-operations then, see if you can find a way to define your 'reference surfaces' for squareness FIRST, and setup based on that.

Blondihacks is working on a #1 I think, and she used her slide-rails as her reference surfaces. They end up getting 2 axes covered. Then, you can use the base/angle plate face for the 3rd.

 

[Janderso]

Good point.
I like it.
The datum point of the crankshaft is the same as the slide rails. If I can square those......

 

[ErichKeane]

Good point.
I like it.
The datum point of the crankshaft is the same as the slide rails. If I can square those......

That's handy! If it wasn't, you could always use a DRO or gauge blocks to offset too.

The silly part of these engines (or perhaps machining non rectangular things in general!) Is that 95% of the work is indicating in a setup. You spend 20 minutes getting it all lined up just to spend 30 seconds running the machine!

 

[EricB]

Jeff,

I'm looking forward to seeing your progress on this one. It looks like they used the same flywheel casting as their #5. They didn't provide any of the piping to connect the cylinders did they?

I've used super glue to hold a few parts for machining with no problems. It's a very common practice in clock making too. Remember this old commercial?

Eric

 

[Janderso]

They didn't provide any of the piping to connect the cylinders did they?

I believe they did yes.

 

[Janderso]

I'm struggling, the machining of the crank journal sets up the datum for the build. .094" below that is the crosshead sliding surface.
I was ready to mill the base before I had established a datum point.
The instructions/plans are designed for a more experienced model maker.
I'm going to go back through Erich's build and check out some other Youtube reference. Measure, measure , measure before cutting.
Here is a start this morning. I had to get the two high opposed corners flat to the base before I could go on.
Set ups and a bit of machining.
I'm comfortable with the base now.
I'll add some pics.
Fortunately I’ve broken cast iron castings in the past so I know to be extremely careful

 

[Janderso]

You might consider your order-of-operations then, see if you can find a way to define your 'reference surfaces' for squareness FIRST, and setup based on that.

I hear you brother. I'll get it.

 

[Manual Mac]

There is an Xlnt thread on building this engine.
On this forum, from Sep 14 2015.
PM Research Engine #7
By tomw
Forgive me if you already have seen it.