Mike's P.M. Research No. 6 Steam Engine

[macardoso]

I like to only have 2 projects going at a time and I really want to scrape in my mill so I have a push to finish this up!

 

[Janderso]

Can you braze filler in place and distress the surface to look like a casting?

You beat me to it Bruce.
Great job on the PM #6.

 

[Janderso]

macardso,
You are very gifted.
I am convinced building these models will make a better machinist out of you.
I made a mistake of ordering the #7. I found I don't like working with such small parts.
My equipment is massive,(this is a family forum) better suited for the #6.
These can eat time as you have so carefully recorded. Maybe when I'm caught up on my to do list I'll try again.
Please keep posting your progress. Very well done sir.

 

[macardoso]

Can you braze filler in place and distress the surface to look like a casting?

You beat me to it Bruce.
Great job on the PM #6.

Would have been a great option, but I have no hot work tools other than a soldering iron for fine electronics. I'm well tooled for precision machining, but zero welding stuff, sheet metal equipment, presses, etc.

macardso,
You are very gifted.
I am convinced building these models will make a better machinist out of you.
I made a mistake of ordering the #7. I found I don't like working with such small parts.
My equipment is massive,(this is a family forum) better suited for the #6.
These can eat time as you have so carefully recorded. Maybe when I'm caught up on my to do list I'll try again.
Please keep posting your progress. Very well done sir.

Thanks very much. This is a lot of work and has definitely pushed me to learn a lot. The #5 and #6 are a good size and none of the parts are all that small. Only downside is they need a big compressor or boiler to run them.

My equipment is massive,(this is a family forum)

 

[macardoso]

So I started on the new connecting rod but only got as far as facing the two sides. The next step is to drill and tap the bolt holes, then split the cap with a slitting saw. Since this requires flipping my mill head 90 degrees to the side, I opted to work on some other parts first.

The eccentric ring is the next big part needing to be done. I started with some hand filing to clean up the exterior flash then milled the two faces to size. I had the part sitting firmly on the parallels in the vise but still ended up with 0.003" of non-parallelism in the opposing faces so I think I need to inspect my parallels and vise to see if something is up. Thankfully this shouldn't affect function and I can always scrape flat if needed.



I didn't get pictures, but in a second setup, I faced the top of the bridge, drilled the connecting hole and oil hole, and drilled, tapped, clearance drilled, and spot faced the holes for the bolts which will hold the two halves together after slitting.

Next I tried out my new Tormach Slitting saw arbor for the first time on scrap aluminum and steel. The blade is 1/16" thick, 3" diameter, 30 tooth and is dish ground.



I got a full 3/4" depth into mild steel using a 1/2" pass followed by a 1/4" pass. The blade has some radial runout but nearly zero axial. The tormach holder is very nice and I suspect the blade itself has runout.



The part was indicated flat using a 0.0005" DTI on the spot faces and then the indicator was zeroed on one spotface.



The blade height was adjusted to zero on the indicator such that the top face of the blade was level with the spotface. The DRO was then set at 1/2 of the blade thickness below zero.



The slitting saw had no issue with the cast iron.



Here is the clearance I was working with.



And split.



A quick file stroke removed the bung of material left by the saw on the top piece.



And the 2 halves lined up perfectly.



Next operation is to bore the precision hole for the eccentric.

I read so many horror stories about slitting saws, but found this to go extremely well.

More to come - Mike

 

[Janderso]

So I started on the new connecting rod but only got as far as facing the two sides. The next step is to drill and tap the bolt holes, then split the cap with a slitting saw. Since this requires flipping my mill head 90 degrees to the side, I opted to work on some other parts first.

The eccentric ring is the next big part needing to be done. I started with some hand filing to clean up the exterior flash then milled the two faces to size. I had the part sitting firmly on the parallels in the vise but still ended up with 0.003" of non-parallelism in the opposing faces so I think I need to inspect my parallels and vise to see if something is up. Thankfully this shouldn't affect function and I can always scrape flat if needed.

View attachment 359515

I didn't get pictures, but in a second setup, I faced the top of the bridge, drilled the connecting hole and oil hole, and drilled, tapped, clearance drilled, and spot faced the holes for the bolts which will hold the two halves together after slitting.

Next I tried out my new Tormach Slitting saw arbor for the first time on scrap aluminum and steel. The blade is 1/16" thick, 3" diameter, 30 tooth and is dish ground.

View attachment 359517

I got a full 3/4" depth into mild steel using a 1/2" pass followed by a 1/4" pass. The blade has some radial runout but nearly zero axial. The tormach holder is very nice and I suspect the blade itself has runout.

View attachment 359518

The part was indicated flat using a 0.0005" DTI on the spot faces and then the indicator was zeroed on one spotface.

View attachment 359519

The blade height was adjusted to zero on the indicator such that the top face of the blade was level with the spotface. The DRO was then set at 1/2 of the blade thickness below zero.

View attachment 359520

The slitting saw had no issue with the cast iron.

View attachment 359521

Here is the clearance I was working with.

View attachment 359522

And split.

View attachment 359523

A quick file stroke removed the bung of material left by the saw on the top piece.

View attachment 359524

And the 2 halves lined up perfectly.

View attachment 359525

Next operation is to bore the precision hole for the eccentric.

I read so many horror stories about slitting saws, but found this to go extremely well.

More to come - Mike

You made this task look easy.

 

[macardoso]

Here is the rest of the Eccentric Ring:

The part was stood up on parallels and very gently clamped in the vise.


I wrote a simple boring routine. This way I could just adjust the boring head and hit cycle start over and over.


Unsurprisingly the setup is not very rigid and I really had issues with my boring bars wanting to chatter. Ended up going with a brazed carbide bar that I ground to an aggressive rake.


Here is the bore finished. Tolerance is pretty generous so it was not hard to hit it.


And here it is with the eccentric.

Looks great, but something was not right... The fit was very tight even though I left 1.5 thou clearance.

Turns out my boring setup was very poor and even though the vise was clamped lightly, the part was deformed. The bore was cut a perfect circle, but when removed from the vise the sides sprung out into an egg shape.

I figured my only chance at fixing it was to try to bend it back straight. This was done over several hours of very gingerly clamping each half of part in the milling vise and squishing it. Move a few degrees on the handle and remove and test the fit.


I was standing at the finish line and POP!

My heart sunk. The cap cracked at the midline right as I was dialing in the last few tenths. Maybe if I had gone slower I wouldn't have broken it, or maybe the part was incapable of bending as much as required. Either way it didn't matter. I don't remember ever wishing life had an UNDO button quite so much.



Anyways, I got 2 new castings from PMR at $4 each. Started facing them and realized I was having accuracy issues due to my vise. Took a 40 hour hiatus from the steam engine to correct the inaccuracies in the vise so hopefully I can make better parts.

Scraping my Shars 4" Milling Vise

Been working on a steam engine and really been having a hard time holding parallelism on parts where one side is machined and then flipped onto parallels in my milling vise. I finally stuck an indicator in the spindle and tested the vise and found it to be almost 4 thou out of flat with the...

www.hobby-machinist.com

I still need to repeat the drilled holes, slitting, and boring, but this time I will be using a different setup, hopefully with better results.

Stay tuned - Mike

 

[Peyton Price 17]

my neighbor used to bore out airplane engines on a jig bore. one cylinder a day and a 150k an engine. he also used to run a CNC to machine caps for oil rigs and the part was the size of a car and cost the same as a house. I'm pretty sure both places were bought up and taken down.

 

[macardoso]

my neighbor used to bore out airplane engines on a jig bore. one cylinder a day and a 150k an engine. he also used to run a CNC to machine caps for oil rigs and the part was the size of a car and cost the same as a house. I'm pretty sure both places were bought up and taken down.

Well if my successes in this project tell you anything, I'd be out of business. Thankfully this is all for fun and learning.

 

[ErichKeane]

Ouch.... is it bad I predicted that ending? I would suggest putting it on a pallet of some sort.