Chris's Diesbar Engine Build

[steam guy willy]

Hi "C"   will you be using locknuts on the bearings for future adjustments and as the original is quite ancient did they have them on the original ??or did they incorporate shims ?? looking really good...
cheers
Willy

[crueby]

Hi "C"   will you be using locknuts on the bearings for future adjustments and as the original is quite ancient did they have them on the original ??or did they incorporate shims ?? looking really good...
cheers
Willy

Hi Willy,
From what I can see in the pictures of the real engine, they used shims, which was very common. I have mine lapped so that the caps are down tight, no shims at this point. Given just running my engines at shows and for fun at home, and without a work load, I've never needed to change the spacing, if I do I can always just file a tiny bit off the bottom of the cap to let it sit down farther.
Chris
 

[crueby]

Yesterday I got some paint on the lower frame and the end X frames. This morning they were assembled onto the base with the vertical columns screwed in place and the top frame set over them. Quite a difference with the color on the frame! It changes the appearance of the cylinders too.

After some sitting and staring at it, and some thinking about next parts, I decided to go for the crankshaft. Got out a nice piece of 1/2" round stainless steel, and cut the blank for the main shaft, and test fit it in the bearings. As expected, slightly tight fit so it will need lapping in, but the bearings were left a hair under size in the bore to allow for lapping, which will adjust for any tiny misalignments in the parts.

Got the pieces for the webs and crank pins rough cut out as well. Here is the 'kit' of parts for the crankshaft:

I'm going for a built up crankshaft, with a 2-1/4" throw, it would have been a massive piece to carve out of one (really) big bar. The webs will be loctited and taper-pinned together, with the crank pins having shoulders turned on the ends to set the web spacing. The center set is for the pump. The crank pins on the cylinder webs on the original engine have a huge nut and shoulder to hold the outer paddle shaft in place - I will make that but will pin those webs in place too for the model - no need to keep it able to disassemble.

Next step was to true up the ends of the webs and take each set to the same length. A work stop made it easy to get them to consistent lengths. They are all slightly long and wide, the thickness is correct for the shaft end of each one. The webs will all get rounded at the ends, with the outer ends tapered down, and the sides shaped in too. And with Michaels help and pictures, I also know that the web over on one end is a replacement, and its shape is slightly different that the other one. Should be fun!

Then over to the lathe to drill/bore the holes to take the main shaft. Could have drilled/reamed on the mill, but this is easier for me, and may be more accurate a fit on the shaft, which may not be the same exact size as the reamers I have. I production-lined this process, spot drilling all 6  webs, then drilling all 6 starter holes, and then boring them out to size one at a time. The exact placement in the chuck is not that critical for making these holes since there is extra on the bar and they will be shaped down around the holes later. The placement of the second hole in each is more critical.

I'm done boring out the first two webs to final hole size, here I'm working on the first one:

test fitting with one of the crank pins (that has had the ends deburred! )

With the first one done, the handwheel on the cross slide was zeroed so I can get the others done quicker - will stop just short of zero on each and test anyway. The final cuts are done with several spring passes, not moving the cross slide but still going back and forth in the cut a couple times slowly, which smooths the cut and takes off that last bit of metal.

One set bored out. These holes will be on the main shaft, not the crank pin, but its the same stock.

Four more holes to bore out, then on to the next stage. The webs are thinner at the outer ends, and I want to thin them down for that before drilling the crank pin holes, just in case the metal moves a touch from taking off on one side only. Unlike the brass/bronze, I can't stress relieve the 303 stainless, and it can move just a little, even on short sections, when milling off one side. Better to do that before boring the second holes, so I can keep the holes parallel. I'll need an alignment jig of some sort, or at least use a pin in the first holes and drill them together.

[cnr6400]

  Great start on the crank Chris! I guess you're throwing all your tooling at the throws....   (that was a bad pun even by my standards...) 

[Michael S.]

Chris,
the initial assembly looks fantastic.
Yes, the crankshaft was repaired once over the years.
Are you offering a 10-year warranty on the crankshaft, too? 😁

Michael   

( Cast steel 10-year guarantee,

Krupp near Essen 1853 )

[crueby]

Chris,
the initial assembly looks fantastic.
Yes, the crankshaft was repaired once over the years.
Are you offering a 10-year warranty on the crankshaft, too? 😁

Michael   

( Cast steel 10-year guarantee,

Krupp near Essen 1853 )

Um, yes!  I guarantee  to myself that it is a crankshaft...   




I'd  like to put in the guarantee  lettering like on the real one, but at this scale the letters are so tiny. Maybe print on a toner type printer and heat transfer them with an iron?      my shop elves are that small, but thier handwriting is terrible!   

[Sanjay F]

Looking at the crankshaft it exudes quality even after all these years, I wonder when the crankshaft was repaired and if its the repair which had the 10 year guarantee or the original - either way its done well, clearly not bought from Amazon 

[crueby]

Looking at the crankshaft it exudes quality even after all these years, I wonder when the crankshaft was repaired and if its the repair which had the 10 year guarantee or the original - either way its done well, clearly not bought from Amazon 

As the engraved letters say, repair done in 1853, originally  made in 1841. Would have been amazing to watch them make it.

[Michael S.]

Only the central section of the entire crankshaft was replaced with a new part—specifically, the section featuring the pump crank. The ends of the crankshaft are fitted with cranks and connected to the counter-crank of the cylinder connecting-rod assembly via a bolt and screw, forming a floating connection. This is the point where the crankshaft can be disconnected from the paddle-wheel shaft. This flexible connection is also necessary to compensate for minor misalignments.
In short, the central section was not repaired; instead, a new one was supplied by Krupp and installed in 1853.

Michael

[crueby]

Thanks for the clarification Michael!  I was thinking it was the end section, but it makes sense that its the center, since the guarantee lettering is there. Do you know why the two end crank webs are different? On one, the webs have straight sections between the hub and crank pin ends:

And on the other, the outer web has a slightly different shape with the straight section recessed in:

Do you know why they are different?
Thanks!Chris

[crueby]

More done on the crank webs. The webs outsides were notched back in the center to begin the shaping.

As suspected, this did let the bars relax just a bit, causing the ends to arc over. Not much, but I want the holes to stay parallel to the web sides so the finished crank does not have any bend to it. So, I did a little trimming to flatten the outer edges square to the holes again - just a light facing cut was all it took.

Then set up with the face around the first holes on the base of the vise and the pair of blocks aligned with one of the crank pin blanks, and drilled/reamed for the crank pin holes. The pump webs do not get narrowed, so they did not need the trimming step.

Over to the lathe, turned up the crank pins. One end of the pins is longer, where the big nut will go:

Test fit of the webs/pins on the crankshaft main rod:

 and made up the stop rings that will go on the outer ends to keep the crankshaft in position. I'll attach these last.

Next will go back to doing more of the shaping on the crank webs. I'll need to make up a holding jig for the rotary table for that.

[Michael S.]

The thing about that one crank looking different is a bit of a curiosity. No one knows exactly why that is. It likely dates back to some repair job from the past. Or maybe the workshop elf tasked with filing a new crank said to himself: "I’m not crazy enough to spend all day filing this thing just to make it look nice and round; the way it is now is good enough, and the pub is closing soon anyway."
Or something like that.

Michael

[crueby]

The thing about that one crank looking different is a bit of a curiosity. No one knows exactly why that is. It likely dates back to some repair job from the past. Or maybe the workshop elf tasked with filing a new crank said to himself: "I’m not crazy enough to spend all day filing this thing just to make it look nice and round; the way it is now is good enough, and the pub is closing soon anyway."
Or something like that.

Michael

    

[cnr6400]

  I'm pretty sure I worked in Plant 2 in Canada of that workshop you described Michael.... the story sounded like a lot of things that happened there!     

[paul gough]

Hi Michael S, you mentioned a few posts back there is a flexible connection between the crankshaft proper and the paddle shafts. Do you know if this flexible coupling was an Oldham coupling, or a more modern one. Mr Oldham an Irish engineer came up with it to align paddle wheeler shafting around 1820s I believe. Regards, Paul Gough.