Monitor Steam Engine

[zeeprogrammer]

Before our regular programming gets interrupted... 

Here's facing/turning a cover down. This is the outside. The hub is 1/4" long, 1" diameter...



Using the cylinder to find that diameter...



Four covers. What appears to be a fifth, is in fact a learning. You can see the chatter.



What I was doing/did...

I set the carriage stop and cut towards that. Move in Y and repeated.
Every time I hit the stop, I backed out to keep the face smooth.

The first time though I didn't have my tool post rotated enough. The cutter was rubbing against the face.
After I rotated the tool post so that only the point of the tool was turning and facing...things went pretty good.

This is great! Normally nearly every part would have been remade twice, if not thrice.

(This is the definition of a jinx.)

[Don1966]

That's cool buddy but I have a question. Why didn't you drill the holes for the cylinder shaft while you had them true in the Chuck?

[b.lindsey]

Ah some progress! Great Zee. I was beginning to wonder 

Bill

[zeeprogrammer]

Thanks Bill...I think. 

Don, there was an earlier post about that. There's also a gland through which the piston rod goes through. My thinking is to do the gland, mount it in the cover, true everything and then drill through both. (The gland is smaller than the outer hub, so I can still hold onto the outer hub.) Not sure if that's a good idea or if it matters.

The other thing was, I was thinking having just an edge against the live center may not be enough. So carve a dimple to get more contact on the live center, and then deal with the piston rod hole.

By the way everyone...the hub you see on the cover is not what goes into the cylinder. That's the outside. It's the other side that will have the 'hub' that goes into the cylinder. That's the one that has to be true...and would be the time to drill the piston rod hole.

But then...how does one get the piston rod gland true?

Caught some flak for being in the shop all day.
You all aren't worth her (not even Cletus)...but I have hopes for some shop time tomorrow.

[zeeprogrammer]

Current plan...does this make sense?

Once I have the inner hubs done (fitting snugly in the cylinder)...

1) go to mill and make the holes/taps to attach the cover to the cylinder
2) drill/thread the outer hub for the piston rod gland
3) make the piston rod gland
4) mount the cylinder in the 4-jaw and center using test indicator on the bore.
4) mount the cover onto the cylinder along with the gland
5) now drill/ream the piston rod hole through the gland and cover.

Should be true, no?

One question I would have is whether the gland hole will remain true as I remove/replace the gland.

Am I way off base here?

I mean here. I know I'm usually off base elsewhere. 

[crueby]

On most of my engines, I try to !make the covers/glands true to themselves (is that Zen machining?), and not too snug a fit in the cylinders. Since the bolt holes allow a tiny bit of play, I wait till the piston is done and installed, using the final fit of the piston/rod to align the cover/gland and tighten the bolts. No matter how true you make the parts, there are tolerances and tiny errors that stack up. Even bolting up everything, truing it as best you can, and then drilling, there will be small errors - alignment on lathe, how true the drill cuts, how well you can take it apart and reassemble later with piston, etc etc. Engineering is a lot about managing tolerances and being able to adjust for them. No matter how you do it, mark everything so it can go back in same place it came from!

Hope that long line of thought helps....?

[crueby]

Oh, and dont forget temperature changes effecting fit, how well the piston rings fit (and what they are made of),  lubrication, wear, all the other things...

[zeeprogrammer]

All good points and helpful.

I have noticed how things change due to temperature. When I did the main bearings...snugness/tightness depended on whether I fit things right after machining or waited until things cooled.

I did plan on using witness marks.

I admit I'm beginning to worry. I didn't think I was doing things in a 'weird' way but many of the comments I'm getting is raising the question.

One thing I noticed...when I trial fit the covers on the cylinders...there's a big difference in how they mate depending on the rotation of the cover to the cylinder. Not sure where that's coming from. I have to believe the hub is good...so maybe the raw rod isn't that round. Certainly, I expect when I turn the assembly it will be (should be) good...but I suspect the diameter will be smaller than I had thought it would. Not a biggie, I'm thinking, but I have to be careful when I mill the flats on the cylinder assembly.

Oh well, if I screw it up, I've learned some things and I can redo.
A whole lot different than letting a programming bug out in the field. 

[zeeprogrammer]

Bored the 2nd cylinder. Only 1/2 a day instead of 4! 
Overall it went pretty good. The finish looks great.
But...at the far reach of the boring bar there was chatter.
Some of that will be taken up by the cover. So for now I'm moving ahead.

Going back to 'how the covers and cylinders will be held by the chuck' and the idea of a spacer.
As it turns out, this won't be needed.
The chuck jaws are within the diameter of the cover.
Had I drawn a real chuck, this would have been seen.

My concern and worry however is increasing.
This business of not having drilled the piston rod when I had the cover mounted 

Wait a second. I haven't even gotten to that part yet.
All I did was the outer hub. It doesn't have to be 'perfect'.

It's now when I need to know. I've started making the inner hub that goes into the cylinder.

 

So do I drill/ream it now?
Is that enough for the live center to hold?
Does it matter if the gland is made later?

[EDIT EDIT EDIT] PAY ATTENTION HERE...

The above is going by the imperial plans. The metric plans show a brass bearing in addition to the gland.
I believe the brass bearing is pressed in.
I don't know if I'll do the brass bearing...but it raises the question for me...
How?
Am I right in thinking the brass bearing would have been pressed,
THEN the cover mounted on the chuck, turned down for the inner hub (thus making it true) and then drilled/reamed?

Still leaves the question of the gland. It has the same reamed hole for the piston rod.

Sorry...this is a lousy post.

[10KPete]

Zee, I've been reading, with great interest, this thread of yours. And I must admit I have received a great deal of entertainment
from your postings and the replies/banter they garner. It must be one of the best threads around!!

With regards to your questions/doubts about turning your cylinders, covers, glands, etc., I want to repeat what someone else
has said some time ago. And it must start in the planning/sequencing stages of the project: When a part is placed in the lathe,
do so in a manner that allows all the features that relate to each other to be turned/bored in the same set-up. This is the best
way, and sometimes the only way, to assure concentricity and squareness of the features.

Your cylinder heads, for example, should be done so the features that must be concentric are done without removing the part
from the machine. The inside face, the registration diameter and the bore for the rod must be done at the same set-up. The OD
also if possible. Remember though that the OD and the gland can be dialed in later and be close enough. But that face, registration
and rod bore must be right dead on to achieve the best alignment at assembly.

Same with cylinders. The bore and one face, the rod end face, must be done in one set-up. The other end of the cylinder can
be less that perfect but will not affect the alignment of the operating parts!

So, in your mind at least, sort out what parts interact with others, how they must align, then plan the sequence so those features
are machined so as to get the best possible relationship between them. If it references to air it wants less attention than if it
references to a mating part.

I'm rootin' for 'ya and enjoying the build!

Pete

[zeeprogrammer]

Thanks very much Pete.

I believe I am on the page of drilling/reaming the piston rod hole when I face the cover to fit the cylinder.
It's not too late either since all I've done are the outer hubs.

But I wonder if the edge of that hole is enough for the live center...keeping in mind that part of the hole gets removed later when I drill and thread for the gland.
I don't see any way of doing that without removing the part.

Assuming the hole is fine for the live center...I think the crux of my problem is how to get the gland hole true to the cover's piston rod hole.
I would imagine I would drill/thread the outer hub for the gland, make the gland (without it's piston rod hole) and then what?
That is, how do I get the cover's piston rod hole aligned with the one in the gland?

Thanks again for the kind words.

I hope you don't mind if I slightly edit your compliment 

It must be one of the best longest threads with the fewest made parts and most silly banter around!!

[vcutajar]

Can't you use the same method that Chris used?

If you are really worried to get the hole in the gland nut concentric how about using the following method:

Make the gland nut first but do not drill for the piston rod.
Machine the cylinder head and tap the hub for the gland nut whilst still in the lathe chuck.
Screw in the gland nut.
Drill the gland nut for the piston rod whilst it is screwed in the cylinder head.

This is just an idea.

Vince

[zeeprogrammer]

Thanks Vince.

That's along the lines I'm thinking.

If I don't do the piston rod in the cover (head) then I would drill through both the gland and cover.
But there's some question how true that would be to the bore of the cylinder.

If I do the piston rod in the cover first...it will be true to the bore of the cylinder. (Should be).
But then how do I drill the gland to be true to the piston rod hole in the cover?

Am I overthinking this?

[Don1966]

Drill the gland nut for the piston rod whilst it is screwed in the cylinder head.
Vince

I have a problem with that. If the Setup is not exactly true when you screw the gland nut back in it could end up giving a offset to the cylinder cover. This could double the offset by the cover amount and gland amount of error depending where the nut sits in the cover.

Don

[zeeprogrammer]

How about this...

If this is true then 

I had mentioned this earlier but forgot...

The gland's outer dimension is smaller than the cover's hub. So it can be on the cover and still be able to hold the cover in the lathe by the outer hub.

So:
1) Make the gland
2) Drill/thread the cover for the gland.
3) Thread gland onto cover.
4) Mount cover in lathe.
5) Face and make the inner hub to fit.
6) Drill/ream the piston rod through both. Should be true.

I'll have to hold onto the outer diameter of the cover to drill/thread for the gland.
Would be close enough anyway.
Maybe clean the outside first.
Later when I assemble for final turning...should be okay.

And it's still not too late.

I'm liking this. Thanks everyone for the help.

Don't hesitate to jump in and say 'Uh...what a minute you fool.' if I've completely missed something.

Pretty soon Marv is going to jump in and talk (yell) to me about planning and thinking things through. 
Ah well. Sorry. 

All of this depends on how well the bore is perpendicular to the cylinder face. What Pete pointed out.