Larrys PM Research #4

[larryg]

So I'm sorta new at this engine building stuff. This is my second engine from a kit. The first, a Tiny Power 104, took 15 years to get running. I hope this one will go a bit faster. I have learned a lot from this thread; https://www.homemodelenginemachinist.com/threads/pm-research-4-build-log.24978/ by member
vederstein. I also used RCDon's build for a lot of information; http://www.rcdon.com/html/6ci_steam_engine_project.html I don't know if he is a member here. So thanks to both these guys for documenting their builds.

The tools starred in the build are a Sheldon 10 and 13" lathe. An Index #40 mill and a Dufour #62 mill. More of the shop is documented on another forum, https://www.garagejournal.com/forum/showthread.php?t=76641

I will be editing this post and will follow up with pictures as soon as I get that figured out. Right now I have a bunch uploaded into an album here if you must jump ahead. Hopefully over the next few weeks I will get pictures pulled into this thread. Life is busy here on the farm this time of the year, but I wanted to get this started. My thoughts are a bit scattered and the pictures may also not follow a strict timeline and some pictures are obviously staged as I forgot to take some of them when I should. Get focused on the machining and not the documentation.

lg
no neat sig line

 

[larryg]

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Boring the crosshead guide on the Dufour.

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I had used a belt sander to get the feet in near alignment to the casting and then indicated so the cored hole for the crosshead was as near as possible centered and in line with the spindle center line. That is the reason for the feeler gauges between the casting and the angle plate. Once bored I used a facemill to square up the face to the bore.

lg
no neat sig line

 

[larryg]

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So after reading Ved's adventures with machining his frame and breaking a leg off of it I wanted to try a different approach. Reading about mini pallets about the web I decided to make a solid base for the working on the crosshead frame. I located 4 holes for the leg to frame holes and also made a spud in the middle located on center of the leg holes so that I could machine either end of the frame as necessary. I plan on turning this into a mini pallet with grid holes when done with this job.

The first two pictures are of making the pallet. The third is the frame mounted feet up so that bottom of the feet could be milled flat and parallel to the cylinder mounting surface. I also drilled the clearance holes to mount legs to the base. Being the legs were so spindly I put a spacer between them to damp out resonance while milling. Still a fear of catching and breaking one so light cuts were in order.

Picture 4 is locating the bore center to the spindle so the holes could be drilled for the cylinder mounting. I really like the bolt hole circle function of the DRO on this mill.

 

[larryg]

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So after locating the center of the bore I set up the bolt circle in the DRO and drilled the holes. In this setup I was so close on height that I had to grind a bit off the end of a screw machine drill to get the clearance between the parts. In the prints it suggests that these holes be located by the cylinder head and use a transfer punch. I have had poor results in trying to locate precision holes in this way and better results by using the dro.

 

[larryg]

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Boring the cylinder was perty much basic lathe boring. Bored to 1.5" per the print

View media item 1504
Set the cylinder on the mill to bore and ream to 5/8". Reaming gave a good straight bore and I will fit the valve to the bore.

lg
no neat sig line

 

[larryg]

View media item 1508This set-up was to get the inlet port drilled and tapped. I used a 3/4" and a 5/16" rod in the bores so the centerline of the two bores would be in line with the top of the vise jaws.

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So with the previous setup I now faced the steam inlet port, somewhat confident that it is parallel to the bore centerline plane.


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Now drilling and tapping the inlet perpendicular to the port face.

 

[michael-au]

No pictures are visible

 

[larryg]

So no one can see any pictures? I was wondering why this thread was getting no traction. Anyone help me out on getting a picture from an album on here on this forum into a post?

Can you see this one;

thanks

lg
no neat sig line

 

[johnmcc69]

I can see the pictures fine on my Fire tablet.

Nice work on the engine Larry, I like your set-ups.

John

 

[michael-au]

pictures are showing up now

 

[karlw144]

I can see all your pictures on an iPad. Nice work.

 

[vederstein]

Ved's adventures with machining his frame and breaking a leg off

Larry,

I'm glad that my misadventures are helping you avoid my mistakes...

...Ved.

 

[larryg]

Larry,

I'm glad that my misadventures are helping you avoid my mistakes...

...Ved.

I learned a lot from your thread on your build, not just the mistakes to avoid. So again thank you for blazing the trail and I welcome any additional input you have if you see me headed down the wrong path. I refer back to your thread a lot when starting a new piece.

lg
no neat sig line

 

[larryg]

So the bearing block and cap come as one casting. I milled the bottom of the casting flat which also mills the bottom of the cap.

After milling the base flat I used a slitting saw to seperate the the base from the cap.

I then squared up and finished the the base. Once that was done I used a strap clamp to hold the cap to the base and drilled through both with the tap drill. Threaded the base and opened up the cap for the clearance hole size. Sorry no picture.

 

[larryg]

Once the cap and bearing base were screwed together it was time to bore the bearing hole. I was concerned that clamping in the vise with just the riser for the oil hole bearing on the vise jaw that it might deform the cap a bit and leave me with a oval hold. So I made a spacer that cleared the oil port boss and put the force on the two SHCS's. It seems to have worked.

I dialed in the height of the base on the DRO so that I would be centered on the split and spotted the point.

I pre drilled the hole and then used a 19/32 drill bit to finish drilling.

The print calls for a 5/8 hole. So I set up the boring head and along comes the 6 yo grandson. "Whatcha doing gpa?" So I explained the process and then proceeded to bore the hole to .652" Hit it spot on too. Checked with the fit with the crank shaft rod and it just flopped around in the hole, Ah Chit.

In RCDons build linked in the first post he built his with bronze bushings from the start. So I ordered up a couple of bushings

lg
no neat sig line

 

[larryg]

I drilled and tapped the crosshead for 5/16-18 amd spotfaced the hole. This I put in a headless screw and used that the chuck up in the lathe. I put a center hole in the other end and turned the od to 1.499" to a good fit in the guide hole in the frame.

I then checked that the rod was in the center of the casting. I milled the ends of the arcs till this measurement was the same either way I i flipped it. I deemed this important because I wanted the connecting rod to be centered in the piston rod. Having this centered then I could use the milled ends of the arcs to reference how far down to mill the flats for the connecting rod.

This was the setup to center the connecting rod and mill the flats for the connecting rod. This little procedure drove me a bit nuts. I'd measure the height of the rod as in the above picture and then mark the high side. Then move to the mill and cut the high side the few thou as needed, and the remeasure only to find the low side was now high by the few thou... It took two tries to figure out the proper way to measure and cut this. I started by using the granite side as the reference but that proved wrong. I had to measure from the top of the cross slide down, and then cut the top side.

Last was to put in the oil passages. This thing has a cross hole from each side, one through the rod hole and then an angled one that intersects the other two so that one oil port gets the connecting rod and the faces of the cross slide. Always fun drilling intersecting holes from 3 directions.

 

[larryg]

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A couple of pictures of marking out the crank pin location. I did not grab pictures of turning the crank disc's but started out with a .500" hole in the center instead of a .625". My thinking here was it would give me some room if I had to recover from a future mistake, or or I had problems with the supplied 5/8" material supplied for the crank. So this setup allowed me the find the height of the crank center and then offset to mark out for the crank pin. I also used this setup to align the casting detail for the crank pin while both crank disc's were on the rod and clamped them together as seen in the next photo.

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So with the discs clamped I put them in the mill vise. I measured from the side of the vise to locate the crankpin so that it was centered on the center hole and the center-line through both were parallel to the Y axis travel. I then bored the center hole to .600" and offset the table 1.25" and drilled and reamed the crankpin hole .375". The hole came out closer to .3752"

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So I turned the crank pin and gave it ~.0007" over for the pressfit. Also not pictured are the crank shafts that I turned to .6005". I was not happy with the material included in the kit for crank shafts so I purchased some ground shaft and used it. The material in the kit was .002" to .003" under and not round.

I pondered how I was going the fixture all this for pressing together and get it straight. I came up with this;

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I had checked both half's of the crank and indicated both crank discs while held in the collet and both were right on. So with one held in the collet and the other in the tailstock loosely I used a clamp to pull them together.

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Once together I indicated on the crank disc and had to tap just a bit to bring the two disc's concentric and the free end of the crank had ~.004" tir. I was happy with that for the moment.

I went to install the crank in the base and discovered that I had made the the crank pin ~.080" to wide and it would not fit down into the crankcase. Memory is foggy, but I think that some bad words were spoken about this time. I walked away and mowed the yard or something. Finally decided to take it apart and turn the crank pin shorter as I material to do that, so I did. Upon reassembly per the sequence above it raised a burr that prevented the crankpin cheek to sit flush against the crank disc. dam, dam,dam. Apart it comes again, dressed the crank pin again, undercut at the cheek, and put a bit more champher in the crank disc and third time is a charm. I'm hoping that my press fits are still tight enough. If not I will make another crankpin if this proves to be a problem. There are also a couple of additional pictures in the album that do not show up in the post but do not show anything new, just different composure.

 

[johnmcc69]

Still making progress Larry, hope you get the crankshaft worked out.

Looking good!

John

 

[larryg]

Still making progress Larry, hope you get the crankshaft worked out.

Looking good!

John

Not so much lately. Spring time here is busy. In the last 2 months I've married off a daughter, filled the hay barn, got the garden in, lots of mowing. Got my old TD6 crawler out of 3 years sitting and did some road work with it. Just finished the county fair which for this household is a few weeks work. Usually after fair things calm a bit and I can have some play time.

So no not much work getting done on the engine. The crank is in the bearings and mounted to the base. It spins but needs a bit of run in or maybe a bit of additional clearance in the bearings. They are a real close fit now but I want them tight to start and then adjust if needed.

lg
no neat sig line

 

[larryg]

So I finally eked out some time to work on this project again. I'm also finding that documenting this is like trying to write a term paper in college. Seems like a lot of work. I sure hope that someone is able to gain from this.

So the next piece I chose to work on was the rod. Checking out the casting I found the rod mostly straight and not tapered so I could hold it in the V block and face off the the two ends. In the picture below I was getting the casting as near as parallel ti the mill as I could, averaging the top and bottom faces. I cut the face flat and near to height. I also went to the small end and cut it flat. I then rotated the rod 180* and indicated the bottom where I just cut and got it parallel to the machine and repeated cutting the big and small end. Now with two flats on each side I could measure on the granite how much to take off to get the flats to size and centered on the rod itself.

Once I had the milling on the faces done and all to size I drilled and tapped the smallend 1/4-20. I decided to use a commercial shoulder bolt with a low head on in it, https://www.mcmaster.com/90969A140. This gives a cleaner look but it also puts all the bearing surface on the crosshead and is subject to forces that will want to unscrew it. I see what happens.

Again there are more pictures in my album, https://www.homemodelenginemachinist.com/media/albums/pm-research-4-build.257/

lg
no neat sig line