Building a Bonzer Bonzer

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Philjoe5

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[FONT=&quot]Hi folks,[/FONT]

[FONT=&quot]I was tempted to title this post “A yanks Bonzer” but settled on what you see.:p[/FONT]

[FONT=&quot]I’m going to build my first IC engine. After much deliberation I decided on building the Bonzer IC engine featured by our very own AussieJim. The Bonzer is his version of the Bonza IC engine. The bonza is an engine designed by John Williams which appeared in several issues of Australian Model Engineering magazine starting in September 2009.[/FONT]

[FONT=&quot]AussieJim kindly provided myself and others with a set of nicely done plans at no cost.[/FONT]

[FONT=&quot]I’ll post my progress of this build in the Works in Progress section but I warn you if you are not entertained by watching paint dry you should not tune in because this is going to be a long build. I decided to post my progress here (with a nudge from AussieJim) in the interest that it may benefit others who have begun or plan to begin building this fine engine.[/FONT]

[FONT=&quot]This project has machining techniques that are new to me. These are:[/FONT]
[FONT=&quot]Making Gears[/FONT]
[FONT=&quot]Making piston rings[/FONT]
[FONT=&quot]Making valves with seats [/FONT]
[FONT=&quot]So in no particular order and subject to my geriatric whim I decided to tackle the gear thing first. [/FONT]

[FONT=&quot]Several posters on HMEM have given great advice as to where to buy reasonably priced cutter sets for module 1 or Diammetrical Pitch 25.4 gears and how to proceed and I thank you all for your help. I won’t go into a lot of detail but I spent 5 weeks to learn how to make a decent set of gears. I made lots of gears that are serviceable but only the last 5 or 6 came out with good, consistent tooth profiles. Note, I’m planning other small projects using gears so while I had my machines set up I made gears for those projects.[/FONT]

[FONT=&quot]A photo of a steel and bronze set of 30T and 60T gears is shown here:[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]The most consistent gears were made using a friends dividing head and I would recommend, if you can borrow one, to use it. Results using a 4” rotary table with a 3” chuck were OK but it was difficult to get consistent gear teeth on my equipment.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]OK, now for some less mentally taxing work I’m going to work on the frame parts and will report back when they’re completed.[/FONT]

[FONT=&quot]Cheers,[/FONT]
[FONT=&quot]Phil[/FONT]
 
G'Day Phil,
Good choice for your engine.
I found the Bonza a nice engine to build & it runs very well.
If you are intending to make your own piston rings & have not attempted this previously, might I suggest that you obtain a copy of Issue 27 of Model Engine Builder Magazine, as there is an extremely good article by Mr. Tom Schwartz on the subject. I made my rings as per the article & was very pleased with the compression produced. Send me a PM if you would like some images of my build.
Good luck with the engine.
Don.
 
Hi Don,
Thanks for the reference on making rings. I did make a ring for a "steam/air" engine I built, more for practice than anything else. I followed the advice of some of my friends in the model engineering group I belong to. It turns out that they suggested doing exactly as Mr. Schwartz did. Of course, the real test of my ability to make a good ring will come with this IC engine.

Cheers,
Phil
 
Luc,
The bore x stroke is 1.18" x 1.18" (30 mm x 30 mm). Yes, it's a bign' - just right for a hamfisted guy like myself.

Cheers,
Phil
 
[FONT=&quot]Bonza Post No 2[/FONT]

[FONT=&quot]I started making the frames from aluminum stock. The side plates and end plates are 12 mm on the plans or 0.472”. Stock material in the USA is in US Customary Units so ½” stock was milled to that dimension. This suits me because typical bar stock can vary by as much as 0.010” (or more) in its flatness and milling the pieces to dimension eliminates most of that variation.[/FONT]

[FONT=&quot](A correction on sheet 5, governor side plate, the 6 mm hole at 44 x 90 is a through hole)[/FONT]

[FONT=&quot]The side plates are not particularly difficult to make and the main bearing housings are also pretty straightforward to machine. Once I bored the housings to 0.750” to accept a main bearing of that size, I made an arbor to hold the work while cutting the bosses on both ends.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]I made the main bearings ¾” OD and 5/8” ID which is close to the 19 mm OD and 16 mm ID on the plans.[/FONT]

[FONT=&quot]The back plate called for a piece of stock 120 x 150 mm or 4.724” x 5.906” and I had a piece of stock just under that on the long dimension so I used it and made a slight cosmetic adjustment to that part which thereby personalizes this Bonzer.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]The end plate has sides at 15 degree angles and the bandsaw was used to remove most of the excess, with an end mill to finish the job.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]I’ve finished the side plates, rear plate, main bearings and their housings the gears, the 60T gear bushing and eccentric. I didn’t want to press in the main bearings yet so using a piece of ¾” round stock I checked alignment with everything assembled and snugged up. I can rotate the shaft easily so things are looking good so far. This picture shows all the parts made for the engine so far is here:[/FONT]



[FONT=&quot]The plans are very detailed showing perspective drawings and many thanks to AussieJim for drawing them up and providing them at no cost to our board.[/FONT]

[FONT=&quot]The cylinder end of the frame structure is a bit more complicated than the side frames so I’ll come back here when that’s completed.[/FONT]

[FONT=&quot]Cheers,[/FONT]
[FONT=&quot]Phil[/FONT]
 
Well done Phil, it's looking better than mine.

I just cut the cylinder end plate with a carbide saw in an arbor in the mill (you can see the saw on John's website cutting the side plates).
I rounded the top with the disk sander and filed out the sanding marks.
The cutout on the side was an afterthought; I needed some clearance so I just ran a slot mill down the side.

I can't wait to see it next year.

Jim
 
[FONT=&quot]Jim,[/FONT]
[FONT=&quot]Thanks for the kind words but your engine runs, mine? Not so much, yet. ;)

My eye perspective is very poor. If I were an artist I'd specialize in anamorphic illusions, but not on purpose:p so I tend to use machines more often.
[/FONT]
[FONT=&quot]I spent last week making the cylinder end plate. Not any tricky machining to it but lots of steps. I wanted to do all the critical drilling on the face in one setup. Unfortunately I was so focused on this goal I countersunk the side plate and cylinder mounting holes on the same side! Although I believe I had a journeyman’s fix to this problem, I elected to start over.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]On round #2, the cylinder and end plate mounting holes and the ¾” radius hole were all drilled in one setup. Then I flipped the workpiece over to only countersink the cylinder mounting holes. [/FONT]

[FONT=&quot]The end plate mounting holes were tapped 10-32 and the oil port hole on the top was [/FONT]
[FONT=&quot]tapped ¼” – 28 NF. All the other machining is largely cosmetic.[/FONT]

[FONT=&quot]I cut most of the excess off the sides with the bandsaw and made the edges true with an end mill.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]The angle on the sides of the plate was measured at 15o on the plans but that seemed a bit low when I made the cut, so I made a small adjustment and touched up the edge with an end mill. [/FONT]

[FONT=&quot]Now I needed to round off the top. I’ve done this using filing buttons or a rotary table. I seem to get most consistent results with the rotary table. So for a part with this much work into it, rotab it is. [/FONT]

[FONT=&quot]This workpiece has a convenient way to attach it to my fixture plate on the rotab. I centered the spindle over the table center, and then moved the mill table for the 47 mm (1.918”) bolt circle of the cylinder. I drilled and tapped every other one of the eight holes 8-32 to hold the workpiece. With the work fastened I used a 3/16” end mill to round off the top.[/FONT]



[FONT=&quot]Now I had one seemingly simple machining step to finish the part. The plans call for a plate thickness of 12 mm (0.472”) and my workpiece was nominally ½”. I’m sure I could deal with this difference down the line. But milling the cylinder side of the endplate true seemed like a good thing and I’m anticipating enough of fiddling at the final assembly without adding to it.[/FONT]

[FONT=&quot]I made a fixture to hold the end plate so I could mill it to its thickness of 0.472”. With the fixture held in the vise, I milled the surface true, then drilled and tapped four of the six holes that attached the end plate to the side plate. Then I milled the work to 12 mm thickness. I wanted to do this in one step but couldn’t reach the very edges (not a critical surface) so I flipped the part around to reach them.[/FONT]


[FONT=&quot]I assembled the four frame pieces and there you have it:[/FONT]



[FONT=&quot]In the spirit of the John Williams build, now that I’ve got the frame, I’ll start making parts to attach to it. I’m thinking the crankshaft is next. [/FONT]


[FONT=&quot]Cheers,[/FONT]
[FONT=&quot]Phil[/FONT]
 
It's looking good Phil, a real masterpiece. And you are not the first person to drill and counterbore all the holes on one side. If you want another one like that, sing out and I will send it to you.

Jim
 
Thanks for the offer Jim but my reject parts bin is already full. That means from this day forward I will never make another bad part;)

Work on the crankshaft has begun. I've not made a fabricated one before but I've seen a lot of them made here. So far I've made the webs and tested them for fit



I'm going to key both ends of the shaft. Then I'll pin all the pieces together after an application of loctite.

Cheers,
Phil
 
I have not had any success with Loctite (but others have). I think the pins do all the work.

Jim
 
Jim,
I think you're right about the pins. I like to use loctite so nothing moves around before I clamp the work in the vise to drill the holes. I read an article some time ago about using loctite. IIRC the major failure mode of the stuff is by having too little clearance in the mating parts. Sort of like silver soldering...the stuff needs to get into the mating spaces.

Tomorrow I'll be pinning the whole thing together. I was experimenting today and I think for a 0.188" pin I want to ream my holes 0.001" over with the loctite just holding the pin in place.

Has it warmed up any down your way?

Cheers,
Phil
 
We have had about 10 days of absolutely perfect weather; cool nights and days around 24-26 degrees (Celsius).

Last Sunday was the best yet: clear blue skies, no wind, 26 degrees and the Club had a run to Dalton, about 66 km from my place. I had the Triumph serviced and polished and was all set for a lovely ride.

And then it blew a fuse 2km from home and I had to abort. So I said naughty words and went back to the workshop. I still don't know why the fuse blew (and that's a worry).

Jim
 
Jim,
Triumph as in motorcycle or car?

[FONT=&quot]I made the two webs for the crankshaft from some ½” CRS. Milled them to 0.394” x 0.984” x 2.598”. [/FONT]

[FONT=&quot]I drilled/reamed the journal hole to 0.500” and the shaft hole was drilled to 0.562”, bored to about 0.6” then reamed to 0.625”.[/FONT]

[FONT=&quot]I’m using 5/8” drill rod for the shaft and journal[/FONT]

[FONT=&quot]I cut another piece of 5/8” drill rod and faced both ends for an OAL of 0.394” x 2 + 0.630” = 1.418” which will be for the journal. With the webs on 5/8” and ½” shafts everything is nicely lined up.[/FONT]

[FONT=&quot]Using the 5C collet block to hold the crankshaft I cut a keyway about 2 1/8” long on each end.[/FONT]

[FONT=&quot]I turned the crank journal to 0.501” on each end for the a length of 0.394”, the web thickness.[/FONT]

[FONT=&quot]I degreased everything, then applied red Loctite to the assembly and clamped it together.[/FONT]

[FONT=&quot] [/FONT]

[FONT=&quot]To pin everything together I drilled/reamed (0.1885”) the shaft holes 0.80” deep and the journal holes 0.60” deep, degreased the holes, used red Loctite and put the 3/16” (mic’d at 0.1875”) drill rod pins in place.[/FONT]




[FONT=&quot]After a few hours I cut the bloody stumps off of the pins with a thin slitting saw and sanded the pins flush. [/FONT]

[FONT=&quot]Now I have to remove anything that doesn’t look like a crankshaft. Note to self: Don’t cut the wrong shaft…. I didn’t, but someone posted here some years back of cutting the journal shaft out after all their hard work and I’ve had nightmares about doing that ever since.[/FONT]

[FONT=&quot]I put the crankshaft in a 5C collet block and cut the main shaft to clear the journal. I used a 4 ½” diameter blade to do that cut. And I had just enough clearance to make the full cut.[/FONT]

[FONT=&quot] [/FONT]


[FONT=&quot]Cleaned up the crankshaft and measured TIR on the end at around 0.008”, not bad at the end of a 9” shaft.[/FONT]



[FONT=&quot]I drilled the oil ports in both main bearings and installed them into their housings. With all screws snug, I can turn the crankshaft by hand with no problem! The ¼” – 28 NF hex bolts are holding the bushings in place for now. Eventually I’ll Loctite them in their housings.[/FONT]



[FONT=&quot]OK, so far I’ve made gears and a fabricated crankshaft, two new skills. More to come before I’m done.[/FONT]

[FONT=&quot]The cylinder is next and will be made from cast iron (Durabar).[/FONT]

[FONT=&quot]Thanks for looking in[/FONT]

[FONT=&quot]Cheers,[/FONT]
[FONT=&quot]Phil[/FONT]
 

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