spot facing cylinder end of base

[dicine]

Hi all, How can I face the outside end of the base round?
Fly cutter the same size?
model I am building is the pm research 1Bi

 

[dicine]

Here is a picture of what I'm talking about

 

[rhitee93]

Hey there! I am currently building the same engine

It is hard to answer your question without knowing what sort of equipment you have to work with, but here are a couple of options.

I cheated when I spot faced that location and used a the circular pocket function on a CNC mill.

A more traditional way would be to set it up against a right angle plate on a mill and use a boring head. If you don't have a boring head, then just mill it off along a straight line just below where the cylinder bolts up. The circular spot face is nice looking, but not necessary to build the engine. All you need is a section that is milled perpendicular to the crosshead slides. I guess you could even clamp the base to the mill table in the normal position and side cut with the end mill to create the right surface.

The great folks around here will probably hove some other suggestions. In case you haven't found my build log yet, here is a link:

http://www.homemodelenginemachinist.com/index.php?topic=18105.0

Good luck, and feel free to give me a shout if I can be of any help!

(edited for type-os)

 

[mklotz]

Lacking a boring head, bolt it to an angle plate, bolt angle plate to lathe face plate and turn spot face.

 

[dicine]

Hey thanks for the replies fellas.

I've been a home shop machinist for over 9 years and the boring head didn't cross my mind :-[

I'm out to the shop now to get started.

 

[f350ca]

Just grab it in the four jaw .

 

[techonehundred]

Just grab it in the four jaw .

For the PM #1, it better have a big throat. It will have to swallow about 2 1/2" to 3" diameter to clear the back of the casting.

 

[kvom]

The title threw me off. Spot facing usually means facing spots in castings for individual fasteners/washers. The pic above looks like a good solution.

 

[f350ca]

Techonehundred, that is a PM#1 being machined. I had to work with what I had, even if it is a little large.

Greg

 

[dicine]

Hi everybody,
Thanks again for the replies on the cylinder end of the base.

Now what is the easiest jig to make for turning the offset on the crankshaft?

 

[f350ca]

The plans that came with mine showed a neat jig for the crank, maybe they deleted it.
You turned the mains first and milled the throws to size.
The jig was a section of round shaft about 2 inch dia. You milled a slot through the center, across the face the same size as the crank throw. Then bored a hole in the slot down the length of the jig. The hole was offset from center the same as the throw on the crank or 1/2 the stroke. One of the mains went into the hole and the slot held the throw. Two small set screws came in from the side to lock the throw in the slot. The jig was then chucked in the lathe, putting the rod bearing on center.
Hope that makes some sense. Wish I'd taken a photo of it.
Greg

 

[f350ca]

was looking for something else and ran across the jig. Hope this helps make some sense of the previous post.

Greg