Engines

Inline Twin Engine Ep. 5

In this episode, I’ll be continuing the work on the crankcase by making the cover for the accessory end of the engine.

First operation, face milling the top:

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Spotting and drilling the hole pattern:

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Roughing the contour:

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Milling the counter bores:

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Finishing pass:

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And an edge break around the contour with the spot drill:

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First side finished:

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I decided to make the gear cover as well, as I can use the same tools and similar set ups.
Again, first step was a face cut:

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Spotting and drilling:

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Roughing:

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Milling the relief for the screw heads:

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Finishing pass:

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Edge break:

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First side of the gear cover done:

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A set of machinable soft jaws were installed in the vise and milled out for the second side operation.

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Second side of the cover finished, still in the vise:

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Another pocket was milled out in the soft jaws to finish the second side of the gear cover.

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The finished parts:

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Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the Projects Page in the top menu.

Yogi

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Inline Twin Engine Ep. 4

The next part I’ll be making for the engine is what I call the cylinder block. The challenge on this part will be the O-Ring groove deep down in the bore and the space for the liquid cooling. The first picture is a sectioned rendering to illustrate how the finished part should look.

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I started with squaring the block on 5 sides on the Bridgeport.

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I then moved the work over to the CNC mill where the top side was faced over and two holes for the bores were pre-drilled. To rough out the two bores I used a long end mill and a helical interpolation. This is by no means the most efficient way when it comes to metal removal rate but it works very well with the long end mill. Another benefit is that it will produce the right size bore so it’s not going to take many passes with the boring head to get it to size.

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And bored out to finish size using a boring head.

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For the O-Ring groove I used a small slitting saw. The saw is 1 x 0.043”
The groove is quite deep down in the bore making it a bit nerve wracking as it’s impossible to see the cut. It’s one of those “let’s hope the code is right” moments…

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To relief the block for the coolant I used a T-slot cutter.

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The next operation was to mill a step to seat the sleeve.

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The last operation on the top of the block was to drill the holes for the cylinder head and coolant passages.

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To top side finished:

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The block is then turned over to drill the mounting holes on the bottom.

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The bottom “flange” is milled.

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And the passage for the coolant inlet is drilled.

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Last, the step on the sides were milled. This is a cosmetic feature as I needed a bit more length on the cylinder head but didn’t want to lengthen the crankcase.

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The finished cylinder block.

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The engine is slowly taking shape:

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Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the Projects Page in the top menu.

Yogi

Inline Twin Engine Ep. 3

In today’s episode, I’ll be making the crankshaft.

This whole engine is built around the crankshaft, and it’s design. It will be a test bed for future use of this idea.

Please refer to Inline Twin Engine Ep. 1 for a CAD rendering of the crankshaft.

The individual parts are turned on the lathe first. This will be the rear, the flywheel end of the engine.

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Second side finished turned.

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The crank discs were turned next:

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What will be the front end of the engine (the accessory end):

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After all the parts are finished turned, it was over to the mill. I machined a set of soft jaws, to be able to hold the part accurately on the bearing seat. It is very important the hole for the crank pin is not only accurate in diameter, but also exactly perpendicular for everything to line up when assembling the crankshaft. Any misalignment would result in binding of the bearing.

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Two of the discs were drilled to be tapped, and two countersunk.

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The front and rear parts being finished as well:

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The different parts, ready for assembly:

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…and the assembled crankshaft:

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The crankshaft installed in the crankcase:

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To demonstrate how well it turned out, a short video:

I’m very pleased how free the crank is running. This part of the build has exceeded my expectations, and I can already envision this type of crankshaft in future engine builds.

Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the projects page in the top menu.

Yogi

Inline Twin Engine Ep. 2

The first part I’ll be making, will be the crankcase. Alongside the crankshaft, the crankcase will be essential on proofing the design of the built up crankshaft.

To better illustrate the steps in machining the parts, I’ll start with the CAD renderings of the finished parts. This will help to visualize the different setups.

The top half of the crankcase:

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…and the bottom half:

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I started with the inside of the two halves, by milling out the pockets that will make room for the connecting rods.

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Next is the outside shape. First, I milled the flange where the two halves will be screwed together. Second operation was to mill the angled relief.

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The same process was used for the top half of the case, except one side is different where it will house the cam shaft.

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The two halves stacked on top of each other, to get the first impression of how this engine will look like.

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The next step is to bore out the case for the crank and cam shafts.

The two halves are screwed together and set up vertical in the vise.

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Using a boring head, I started with the bore that will hold the camshaft.

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… and continued with the bore that will hold the crankshaft bearings.

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At this stage the crankcase was faced over, to ensure the surface is perpendicular to the bore, and the hole pattern for the cover was drilled. The operation was repeated on the other side, machining the case to its final length.

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The last operation was to drill and bore the top to finish the case.

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The finished crankcase (minus a few threads needing to be tapped  ;) )

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Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email me at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the projects page in the top menu.

Yogi

Inline Twin Engine Ep. 1

After the last couple engine builds were single cylinder engines, I felt it’s time to build a multi cylinder engine. I settled on a 2 cylinder engine of my own design.

The unique part of the design is the built up crankshaft. The inspiration for the crankshaft comes from H. Schillings, a german model engine builder. It utilizes large, thin section ball bearings to register the different parts accurately. The idea is to have easy to make parts that will assemble to a strong, true running crankshaft. If this crankshaft design proofs to be successful, I already have plans to utilize this design in future engine projects.

The goal for the engine will be to have a well running, slow idling engine. I set the compression ratio at a modest 5.5 : 1. This figure is a stab in the dark, as the compression ratio is a compromise between performance and idle characteristic of the engine. The slow idle is important to me, and I feel I can achieve what I’m looking for with the mass of the flywheel and crankshaft combined.

The engine is built up from bar stock. Throughout the design, I tried to simplify the parts as much as possible without compromising the look too much.

The engine will be liquid cooled, requiring a full set up with pump, fan and radiator.

A few dimensions to get a feel for the size; Bore 32 mm, Stroke 34 mm, Flywheel diameter 90 mm, Height to top of cylinder head 178 mm

I modeled the engine in CAD. To illustrate what the finished engine should look like, I’ll start with a few renderings:

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The built up crank shaft:

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Thank you for visiting my shop.

If you have any questions about the engine or any of the other projects, please leave a comment below, or email me at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the projects page in the top menu.

Yogi

SAM Hit ‘n Miss Ep. 7

To continue the story of the SAM twins, we have to fast forward to my next visit to Switzerland, which was a little over a year later. The project remained more or less idle, as it was back to reality for the both of us. My brother did finished a few parts, like the crankcase pressure regulator and the fill plug.

I regularly received an update, saying the engines are doing well and running. The engines got some running time for break in and to give them a good shake down…

The wood boards for the engines were made by our dad, as he is the wood worker in the family. The box for the battery, I picked up at the local crafts store.

Another addition to the engines was an oil level sight glass.

Here, the two finished engines running next to each other for one last time, I was taking one of them home with me.

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The engine, as it is today in my shop. I occasionally take the engine out and let it run for a while. Every time I run the engine, it brings back the memories of the great time I had together with my brother in his shop.

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This concludes the SAM project. It was a very special project for both of us. We are  contemplating doing something similar again, as we had so much fun…

 

Thank you for visiting my shop.

If you have any questions about SAM or any of the other projects, please leave a comment below, or email me at yogisworkshop(at)yahoo.com

For other projects from the shop, please check out the projects page in the top menu.

Yogi

 

SAM Hit ‘n Miss Ep. 6

Now we know we have two running engines, and continue the work on the hit and miss governor and some of the finishing touches.

The “trademark” 5 holes were added to the flywheels.

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Here a picture of our test set up on the bench, with the two engine side by side, and the finished flywheels installed.

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The last major part we needed to make, was the hit and miss governor.

This was quite time consuming, as the governor is made up of a number of parts, all rather intricate. Unfortunately we didn’t take pictures while making the parts, so we will jump right ahead to the finished governor.

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…and the hit ‘n miss governor in action:

 

The 10 days where up, and my visit was coming to an end. There were still a few little things left to do, but they will have to wait for another time.

When we started, we really didn’t know how far this project would go, especially in the time frame we set ourselves. Having two complete, running engines was amazing.

My brother, and yours truly posing with SAM for a photo.

 

In the next episode, we’ll finish the story and complete the last few bits and pieces.

 

Thank you for visiting.

If you have any questions, please feel free to leave a comment and I’ll get back to you.

Yogi

 

 

SAM Hit ‘n Miss Ep. 5

We are getting really close to see if there is life in these engines. The last thing needed before a test run, is the valve train. These parts are very time consuming, requiring a number of different set ups.

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No CNC equipment in my brothers shop (at the time of this build. He has since added some new equipment to his shop). To make the radius on the parts, we used a fixture to hold it in the dividing head.

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The (almost) finished parts…

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…as the rocker arms needed the radii added.

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Now we have everything together, and are ready to give it whirl.

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And lo and behold, the engine fired right up on the very fist try!

 

We where prepared to spend some time adjusting and tinkering, as on some of our previous engine builds, a considerable amount of fiddling was required to get them running. No need on this one, it ran beautifully.

This was our first internal combustion engine we built. The excitement was enormous.

This was at the end of day 8 of the project. Now we have two more days to finish the hit and miss governor and put the finishing touches on to the engines.

 

Thank you for visiting.

For other project from my shop, see the projects page in the top menu.

If you have any questions, please feel free to leave a comment and I’ll get back to you.

Yogi

SAM Hit ‘n Miss Ep. 4

We continued to make parts, steadily getting closer to completing the engines. By now, we were on day 5 of our venture, and half way trough my short stay. Things were looking good and we felt confident to finish the engines before I had to leave.

Both of the crank case covers, front and rear, are finished.

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…so are the valves and valve guides.

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The crank case feet are being finished.

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And an other shot of the current state of the project. They are starting to look more and more like engines…

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The cylinder heads are mounted, and the engines are fixed to a temporary board in preparation for the first test run.

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It wasn’t just my brother and I spending all our time in the shop. We had time for the family too. Here I’m getting some help from my nice and god-daughter Karin. Lots of deburring to do…

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Thank you for visiting the shop.

If you have any questions, please feel free to leave a comment and I’ll get back to you.

Yogi

SAM Hit ‘n Miss Ep. 3

The cylinder head is one of the more complex parts of the engine. It required a number of set ups in the milling machine, using a dividing head.

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The crankshaft is next. It is built up from individual parts. To insure a true running crankshaft, we machined the crank webs as pairs. Here, the holes for the crank pin are machined, using a boring head.

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The crankshaft finished assembled:

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The connecting rods being machined:

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Here a shot of the two rods, almost finished. The only thing missing are the chamfers on the big end, which are needed to clear the crank case.

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The bronze split bearings being turned.

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The finished rod, piston and cylinder.

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The pistons are made to a very close fit to the cylinder. The piston is about 0.01 mm under size, which allows it to move free, but is still air tight. The groove in the piston is intended as an oil retention groove. No piston rings on this engine.

In the two short videos below, we are demonstrating the fit of the piston in the cylinder. Holding one end of the cylinder closed against the palm of the hand, the trapped air makes the piston spring back until it is released, allowing the piston to fall free.

We are making good progress, and will continue in the next episode.

 

Thank you for visiting my shop.

If you have any questions, feel free to leave a comment and I’ll get back to you.

Yogi