Building Val a one cubic inch four stroke single

[Art K]

Hi all,
Here is the beginning of the build article for Val. It is a OHV four stroke single designed by Brian Fairey It has a 1.124 bore and 1.1 stroke, and was featured in issues 15-16 of Model Engine Builder magazine. I will not be building it straight from the print but will modify it as I see appropriate. My Upshur single will run till its out of gas w/o overheating and that's something I'm aiming for with Val.
I started with the crankshaft. This is one of the areas that I veered from the plans. Brian designed this with 4 parts, the shaft with counterweight, the rod pin on one half and on the other side the shaft with the disc that drives the cam silver braised on. If I could have made it in one piece I would have, the next best thing was two. Here is a photo of the setup in the lathe with the crank throw complete.
The clamp bolted to the faceplate made a tremendous difference in the balance. I will admit right now that I am guilty of not having the camera on hand when I am working in the shop and some of my photos will be staged after the fact. I wanted to use an emoticon here but there are so many!
Art

[Don1966]

Nice start Art, but you have me curious as to what your using to hold the crank in the lathe to give the offset for turning. Are you turning between centers here, it's hard to make out?

Don

[Art K]

Don,
Yes I did turn it between centers. Dead center on the headstock, live on the tailstock. I then flipped it and turned the bearing diameters and the threads, which I neglected to take a photo of but I did for the next step machining the counter weights. I might add that I listened to George Britnell answering ?'s about what material to use and did get a length of 1144 for the crank.
Art

[philjoe5]

Looks very good Art.  I'll be checking in on your progress

I have a nice supply of 1144 drops from a local machine shop.  I really like working with it.

Cheers,
Phil

[Art K]

Phil,
I have to agree that 1144 is one of the easiest steels I've ever worked with. As easy as I made the first half of the crank sound the one in the photo is actually the second. In an attempt to leave the finished crank throw unblemished I put a piece of gas line on the finished turned diameter. Not realizing how much that would flex when I tried to chase the threads. Needless to say that all made the second half easy, all that roughing down from 1 1/2" already done. That crank throw made a great driver when I flipped it over. Small parts like this I turn a center in the three jaw and let the pin drive off the jaw. I turned everything to +.0005 and polished the shaft to fit the bearings. I bought a roll of super finishing cloth at NAMES a few years ago worked great for this.Here is the end result of the two halves of the crankshaft project, plus a preview of the finished crank case.
Art

[Don1966]

Did you have the crank case already done or you just didn't take any photos? Very nice work Art. 


 
Don

[b.lindsey]

Nice start on what looks to be a fine project Art. I will be following along also.

Bill

[stevehuckss396]

I'm here too! Waiting for the next post. Looking forward to seeing your progress.

[Art K]

Don,
I am actually a few steps ahead at this point in time. After the crank I started on the crankcase. I had an over sized chunk of aluminum and set it up in the vise cleaned up the top with a fly cutter then with an end mill, cleaned up both sides and set the center from that and machined it to size. To do the 45 degree cuts on the corner I used a 90 degree chamfering tool so I could cut the whole top side in one setup. Flipped it over and did the bottom side using the same offset dimensions. I had decided to turn it in the lathe but didn't want to use the 4 jaw so I indicated it vertical, used the edgefinder to pick up the center and used the boring bar to turn a stub I could use to chuck it up in the 3 jaw.
This photo is the end result of the boring and turning on the first end. I don't have a photo but next I turned it around and bored the ID for the crankcase and the big end bearing. I then set it back up in the mill and drilled and bored the top for the cylinder, and drilled and tapped the cylinder mounting holes.
After that I set it on end and indicated the back cover bore and drilled and tapped those mounting holes.
That completes the crankcase but for the point to make sure you don't have 6-40 taps mixed in with your 6-32's.
Art

[Don1966]

Thanks for those photos Art. Being new to the forum you should know we like photos, that's what makes this forum so great and the people too of coarse. I will be following you on your journey.

 

Don

[Art K]

Don & all,
I shall make an attempt in future work to carry the camera out to the shop with me! I know how folks on the forum love photos.
Art

[philjoe5]

Art,
The finish on your parts is to die for!  Great progress report.

Cheers,
Phil

[Art K]

Next I went about installing bearings, polishing shafts to fit the bearings to a slight press fit. Upon installing the crankshaft I discovered some discrepancies. The large main bearing is .035-.05 of an inch to deep. This made it deep enough to bind up on the back side. As you can see in this photo the bearing is significantly deeper than the outer case.   
I looked for a washer .04 thick and put it together between the crank and the bearing. Then thinking better took an old chunk of free machining turned the OD to just fit inside the bore, and the inside so it shielded the bearings seal but didn't touch the inner bearing race. I then used the height gauge to calculate how much shim I would need to give me .005" preload on the bearings. Then using some smaller stock I turned and bored it and cut off several slices in different thicknesses.  I ended up with about .035 clearance between the crank and case. Then using some smaller stock I turned and bored it and cut off several slices in different thicknesses. Hindsight being what it is I should have bored the bearing depth as deep as the width of the bearing and the large diameter of the shaft longer and cut it shorter to fit. Now I have to load more photos onto photobucket.
Art

[Jo]

 

Art, Special request for those of us that don't know this engine any chance of a GA or picture of one so that we know what you are making 

Jo

[Bearcar1]

To go along with Jo's request, and for those of us that take great pleasure in pouring over plans sets and drawings, (what. who doesn't?) Are the drawings available and from where? Thanks and it looks like it is going to be a beat when you are done. Nice work so far Art. 


BC1
Jim