Thank you all
I feel somewhat embarrassed by some of the accolades given...
If it were not for many others who have selflessly shared their build logs, I would not be in a position to do the same either. The Grasshopper build Stan mentions was never intended to be a tutorial. In fact, it was very much shared to get input and ideas from more experienced members. Eric mentioned "trying to raise the bar a notch with each" I fully agree with that, and it's helped me a lot along the way. Since my first runner built over a weekend with only my lathe and extremely limited tooling, I've taken the advice from more experienced builders to not aim too high. After the thrill of finishing each engine, I'd sit down and evaluate it very critically, identify one or two areas that needed improvement, select a new project that would emphasize those areas and start on the new build. So engines were built with a focus on improving accuracy or surface finishes or detailing or painting or setups or purely to get to grips with new tools as my collection grew. There were also some engines that were purely taken on as "bee in the bonnet" ones. Those were taken on as a personal machining challenge purely to see if I could build them (The Lamina Flow, Little Blazer and to some extent the Elbow and Kimble engines).
Carl (Zee) once mentioned sitting back and looking at one's progress once in a while. All I can say is DO IT! You'll get a very nice surprise.
Even though sharing build logs are public, building engines is very much a personal thing to do. Other peoples build logs and skill levels can be both fascinating and awe inspiring to look at, while at the same time also being truly intimidating. I still get that "I'll never be able to do that!" feeling when looking at some of the great engines shown here. It's times like this that I'll take a "Carl" moment, get up, and go and look at my humble collection. There's few things as satisfying as looking over the collection and actually seeing that I've made progress. Five years ago, should I have happened to see some of my own engines, I would definitely have felt a bit of awe and intimidation... Now they are tangible results of a lot of hard work - with loads of memories built into them. Make no mistake, there's still a LOT of room for improvement though!
The best thing about this is looking at my earliest work that next to some later ones looks a bit shoddy and crude, and KNOWING that when I made them I gave them my best go. There's a lot of members here that's seen me build them, and I cannot recall anybody ever giving bad remarks about them - just support and constructive criticism - often from those very people whose work intimidated and overawed me.
That's the crux of the matter. MEM is for sharing our hobby of building model engines and related items - in an environment that is non-judgmental and supportive. That is also why the forum owners decided not to implement any form of rating system, project of the month or any other form of highlighting.
Every member's contribution is equally valuable.
For those that feel their own efforts are not worth posting up - You need not worry; they are! You're almost certain to get valuable advice along the way, just like I did and still do, and in the process indirectly help someone else as well. Don't worry about going into each and every detail, or long write-ups or anything - just post up your progress as you see fit.
As to Eric's idea of a "follow the leader" build...
I agree that it will be great to see members doing versions of the same engine build, but each in their own build logs. It's pretty much guaranteed that people will have different sets of tooling at their disposal, and would have to resort to different ways of building the same parts. There's no "build leader" required - just start up your own build log of an engine even if it has been shown before. It's always great to see the different ways in which the same parts can be made by different people. Your own version of a build will not be judged against someone else's. We're here to share our passion for a hobby and have fun along the way - not to crack people down and get into flaming wars.
I'll get off the soap box now and get on with the build.
The cylinder block needed it's four mounting holes drilled and tapped. These are fairly shallow holes, and one needs to be careful not to break into the cylinder itself. The depth gauge on my mill's quill is downright crude, so rather than checking the depth while drilling from that, I opted to use the quill fine feed. There's two idiosyncrasies with that though. My mill is metric, but the quill feed is imperial - at 2.54mm per turn. The other is that it's dial is not zero-able like the other hand wheels on the mill. I just have to live with the first (for now). For the second, I use a crude way to zero the dial. I feed the drill bit down to lightly touch the workpiece, then lock the quill in place with the fine feed handwheel still disengaged. Then I turn the still-disengaged handwheel at least one full turn in the direction needed to feed the quill down and to zero on the dial:
Then I lock the fine-feed to the quill. The full rotation before locking takes out the backlash in the fine-feed worm and wheel, which is fairly big on my mill. Then I simply loosen the quill, and lift it using the fine-feed wheel. From there, it's easy to drill slightly more accurate holes - I did this lot of 1.6mm holes to about 2.94mm depth by feeding a full turn on the handwheel and up to 0.4 on the dial:
The port hole was also drilled as you can see.
Remember that I'd forgotten something on the base ? - I forgot the port hole in that, so I picked up a reference point to drill it from one of the mounting holes:
Next it was on to some tapping... It would have been better to tap the mounting holes in the cylinder block as I drilled them. Well, I forgot... So I brought out the set of M2 taps. The normal starter tap shown here mounted in the aluminium holder has too sharp a taper for shallow holes, so it was replaced with the normal final tap in the middle. The tap in the steel holder is an old final tap with the tip ground flat to make a nice bottoming tap:
The holes were tapped into the cylinder - for some reason I forgot to take a photo of that, but I just held the cylinder block in my small Myford vice and used methylated spirits as the tapping fluid.
On to making the 45 degree bevels on the cylinder. I don't have a tilting vise, and while I could have used a protractor to set them up, I went for the pair of home-made "parallels" I mentioned earlier in the thread. When I made them they were done as a pair - but the V sections I made into them only lines up one way - so I checked that with a drill bit:
Those were installed in the mill with the cylinder block mounted in the V, and the ends protected from damage with bits of old business card:
I didn't do a lot of mark-out for this; just eyeballed the first cut to depth, then flipped the cylinder in the V and made the other one identical:
Another spot of rubbing on the 320 emery - once again keeping track of the "grain" direction to match the column:
The finished cylinder block:
And mounted on the column. You'll notice that the top of the cylinder block lies slightly below the top of the frame
. When I made the column I forgot that I'd be using 12mm stock for the cylinder - it was made for a 12.7mm thick cylinder block, so it now stands about 0.3mm proud. I'll sort that out later (could have kept quiet about it and fixed but mistakes must be shown too):
Well, that last photo finally caught up to where I stopped two weekends ago. Last weekend I did "work" work installing some nifty servers and storage systems at a client. A light wrist sprain (not shop related) didn't help productivity much this weekend either, but I did manage some more...
The lathe is fairly light to operate, so in deference to the wrist, I went with a start on the bearing. I could have used phosphor bronze for it, but intentionally started making it from a bit of 10mm hex brass. The outer diameter of the "thick" section of the bearing isn't all that critical - it must just be thick enough to allow one to solder in the air connection later, so I just barely turned the hex bits off to round over the needed length of stock and faced the end:
That was coloured in with a permanent marker. The length of the turned down section of the bearing is slightly important - and if built per plans should be 8.33mm (21/64"). However, as I'd used 6mm stock for the column instead of 6.35mm (1/4"), that needed compensating for - otherwise the bering will be too long and push the crank disk out of the cylinder center line. So I marked it out at a round 8mm from the end:
It was turned down a bit - not quite to the marked line yet, and then the very end was slowly turned down a bit closer to size and the end given a generous chamfer with a small file:
The bearing must be a press fit in the frame - but that ~3mm long bit will stick out on the other end of the frame, so I used a dirty rotten trick. I turned it down further, carefully taking readings off the cross-slide handwheel, just by 0.0005" (0.01mm) infeeds at a time when approaching size - testing with the column till it _just_ slipped onto it:
The Myford's dials are graduated in 0.001" intervals, but it's quite easy to "read between the lines" and get down to 0.0005" feeds. Also, on the Myford, the infeed read from the dial is actual infeed, so the diameter of the workpiece got reduced by 0.001" ( 0.02mm) at a time.
Then, to finish the turning, I took the current reading on the cross-slide, backed it out and fed it in 0.0005" (0.01mm) short of that last reading and finish-turned the entire section up to the marked line:
Ok, so that wasn't very precise was it? - Well, it actually works quite well (I've done that on Elmer's Simple Wobbler and Scotty engines in the past). It gives an adequate press fit for the bearing in the column, and the section at the front that just slips into the column means later when mounting the bearing one does not have to press the bearing all the way, but rather just on the section that needs it. Like I said, a dirty rotten trick, but it works for me
You might have noticed that there's quite a "generous" rounding left in the corner from the radius on the tool tip. That I'll address later
.
With my imperial -> metric conversion, the crankshaft will end up at 5mm, so I drilled the workpiece through at 4.8mm (to ream to 5mm later) - to just deep enough to part it off later:
If I'd drilled it deep enough to use my 5mm hand reamer on it, I'd have wasted an unnecessary amount of parent stock. I'm stingy with my brass...
Next I marked the flat at the number 1 chuck jaw position:
With the workpiece removed from the chuck, I marked the distance to where the air connector hole must be made:
Then it was off to the mill. The main reason I'd used the hex stock was to make the next step easier - I simply clamped up the workpiece level in the vise and across flats. No DRO allowed here, so I used the "bit of plate" method to find the center. Here it's not centered yet; it's centered under the chuck when the plate lies flat when lightly pressed down with the drill bit:
Don't adjust things with the plate nipped up... just lift off, adjust a bit, nip the plate down lightly again, till it's lying flat:
And once again, check with the spindle rotated 180 degrees:
With the center located, I could spot the hole location on the line:
That was then drilled 2mm through into the bore, followed by a 3.2mm hole a short depth into the stock:
Well, that's where I had to leave off. I'll see how things go this week during the evenings, but there's a strong possibility I might not get around to doing any more till next weekend.
Kind regards, Arnold
