# Bonza hit and miss engine designed by John Williams



## airbus

Hello all, here is photo of Bonza hit & miss 28.3 cc engine designed by Mr John Williams of Melbourne.

He kindly supplied me a set of drawings to build this during 2010 and has given permission for me to provide the same to this hobby site for personell use.

I think I have today uploaded the drawings etc in 3 parts. Bonza plans, Bonza Notes and Bonza photo.


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## ttrikalin

Airbus, 

this is a beautiful build. Any vids of it running? I'd like to listen to it's sound. 

very impressed, 

Kudos 

tom in MA


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## ttrikalin

But I cannot find the plans and the notes. 

where did you upload them? thanks in advance, 

tom in MA


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## airbus

Bonza plans etc uploaded in the download section, I did not get any error message so I don't know what happened, will try again. Regards.


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## airbus

Hello, I've tried to upload plans etc again (3-parts) each time and again 1-part today, it seems to work without any error messages, I must be doing something wrong so I've given up.


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## JohnS

Tom in MA

You can hear (and see) a Bonza running at http://start-model-engineering.co.uk/category/hit-n-miss/

John-Som


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## JackG

Could the reason you're having problems uploading because of too large a file size?


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## airbus

Hello,
Before I uploaded I checked file index and there are some files there (15mb or bigger) so I thoughtit would be OK.

Kind regards.


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## vasjo

Hi Airbus,

 Just briefly introduce myself.
 I am a teacher at a technical school to teach pupils aged 17 and 18.
 I myself spent several years making small steam engine little, and have also 3 years ago tried this at my school.
 Well it was a great success, the students were asking more than this in the future to continue to do so.
 The first engine was a simple steam engine, one year later, we built a flame eater per pupil and a 2 - stroke 12 cc engine with a class.
 Last year I used my class a 5 cylinder radial engine gebouwt, the colleagues build a 4-stroke, a 2 stroke in January and February Sturlings Knights and another student at a Yes fan.
 So as you can see, both teachers and students fascinated by engines.
 For this school year I started with a V-8 engine and colleagues with the Comber Rotary Engine.
 Since I'm always looking for new ideas have I met you Bonza pretty disappointing.
 But I can not find the drawings and attachments in the download area.
 Would it be possible to email it to me then I projecht prepare and make the future look compline.
 I will make all the plans have yet to convert to mm I suppose.
 Here are some sites where you can admire our work.

http://www.vasjo.be/Luchtmotoren.htm

 [ame]http://www.youtube.com/watch?v=hSUxxFpPnk8[/ame]


http://www.youtube.com/results?search_query=vasjo1&aq=f

 With friendly greetings,

 Joseph Vaesen from Belgium

 Teacher at Wico Campus TIO Overpelt


This entire letter posted here because you can not find your account email.


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## bearcar1

Hello Airbus and welcome, perhaps the difficulty in uploading the plans for this suberb looking and sounding engine is because of the file type being invalid. Where the files in a .zip form or .pdf? Have a look at the accepted file types that are listed when you go to the upload page and it asks you to select a file. I do hope that you are able to get the files up here as this engine is quite an interesting one.

BC1
Jim


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## camm-1

Hi!!
I realy want to build the Bonza Hit & Miss!
Does anyone now how to get the drawings?
Or do the downloads work now? cant find it anyway.

Ove


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## metalmad

Hi Ove
The "Bonza hit and miss" was published in "Australian Model Engineering" over about 6 issues I think
It may have been from issue 146 to 151.
I was going to build this myself (and still might)
I think the designer is a member here somewhere
Pete


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## AussieJimG

Hi Vasjo, I am still working on the drawings of my version of the Bonza to send to you. It used to run perfectly on one of Jan Ridders' vapour carburettors and then it decided not to do so.

For some time, I have been chasing down the problem - new rings to give good compression, messing about with the mixture and so on. For reasons I do not understand, it will only run with a very rich mixture (at least according to an exhaust gas analyser I borrowed)

I have just finished building a carburettor like the one in the magazine (well nearly the same) and the engine once again runs. But still the EGA shows a very rich mixture.

I will continue with the drawings and send them when they are complete. Sorry is it taking so much time.

Jim


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## camm-1

AussieJimG  said:
			
		

> Hi Vasjo, I am still working on the drawings of my version of the Bonza to send to you. It used to run perfectly on one of Jan Ridders' vapour carburettors and then it decided not to do so.
> 
> For some time, I have been chasing down the problem - new rings to give good compression, messing about with the mixture and so on. For reasons I do not understand, it will only run with a very rich mixture (at least according to an exhaust gas analyser I borrowed)
> 
> I have just finished building a carburettor like the one in the magazine (well nearly the same) and the engine once again runs. But still the EGA shows a very rich mixture.
> 
> I will continue with the drawings and send them when they are complete. Sorry is it taking so much time.
> 
> Jim



Hi Jim!
I´m looking forward to your drawings ;D
Ove Larsson 
Sweden


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## AussieJimG

Hi Chaps,

I had some time off the Bonza drawings for a couple of other things including a trip to UK to the Harrogate ME Exhibition. What a treat that was for a bloke from the outer reaches of civilisation. But I am now over the jet lag and back on the job.

In the meantime: Airbus, could you send copies of the drawings to me please and I will have a go at getting them up on this site. There are a couple of other blokes in Oz who are also interested so maybe we can get something going here.

Jim


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## AussieJimG

Hello again,

I have now finished the drawings for  my version of the Bonza engine. I have called it Bonzer to distinguish it from John William's original. But the drawings total about 15MB even in zipped form (they don't compress much) which exceeds the upload limit for this site.

Also, I am a bit concerned about putting my drawings up since the change of ownership and policy.

But if any of you would like to send me a PM with your email address, I will send them to you. Hopefully, everyone interested will reply at once so I can send them all together.

Cheers

Jim


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## AussieJimG

Brian, Tim, Steve, Ron, Greg,

Here you go chaps, the drawings have been emailed to you.

 Please note that I didn&#8217;t have a CAD package when I built the engine so these drawings have been produced from measurements and bits of paper and backs of envelopes that were used at the time.

The head with side plug and the head with side plug and valve guides have not been built &#8211; they are just the way I think I would do it next time to avoid the problems with the original.

There are a few photos taken during construction on John Somers&#8217; website here: http://start-model-engineering.co.uk/category/hit-n-miss/

I think that drawings without errors are like computer programs without bugs: just those in which the errors/bugs have not yet been discovered. So despite my checking, there are bound to be some errors in the drawings and I will be happy to have these pointed out by any of you who use them.

If you use the Alibre CAD package and would like the Alibre files, I am happy to make these available as well.

Please keep in touch and let me know how you get on.

Cheers

Jim
AussieJimG


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## GKNIPP

Those are some beautiful plans my friend!!! The engine is a treat as well!!!!  I am in the process of converting them to imperial dimensions as we speak.

Greg


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## AussieJimG

Greg has spotted a couple of omissions in the drawings so I will update them. There is a cutout missing from Item 80: Governor Mounting Plate and no drawings for Item 175 Magnet Mounting Ring or Item 114 Driving Dog.

If those of you who have the earlier drawings would like the updates, please let me know (I am not sure I have a complete list of those to whom I sent the drawings).

Note that Greg is converting the drawings to imperial so if you need them in inches, Greg might be prevailed upon to make them available.

Jim


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## GKNIPP

Only with your permission Jim!!!!  I don't want to step on your toes as you did all the hard work.

Greg


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## AussieJimG

Press on Greg! The really hard work was done by John Williams, the original designer; all I did was to modify the engine to suit my limited abilities and re-do the drawings in Alibre.

Speaking of Alibre: I have posted a CD with all the Alibre files in it. It really is the easiest way to do the Imperial conversion (I know from doing several the other way). The thing that will get you is the thread conversions but that is simple too - just edit the holes and change the thread specification and it is all done.

I am looking forward to seeing the finished conversion. And, of course, the build log.

Jim


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## AussieJimG

Ian, Lonnie, Jim the drawing files (complete with Greg's amendments) have been sent. I know some of you have received them.

I am now looking forward to seeing some build logs to brighten my day.

Thanks all of you for your interest.

Jim


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## AussieJimG

The lines are running hot. Jim, Bertil, Ken and Leonard should now have the drawings.

This is getting exciting.

Jim


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## GKNIPP

Hey there Jim, I am almost affraid to say this for fear of upsetting you, but, I found a few more dimensions and features omitted on the original plans. Do you want me to just send you an e-mail with the errors as I find them or just wait until I think everything has been addressed?

I hate to bother you, but, I guess I am trying to help work out some of the bugs and make things easier for the other gentleman to work with. I hope you don't mind.

Greg


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## AussieJimG

Far from being upset Greg, I am very grateful to you for going through the drawings in such detail. It is almost impossible to pick up those errors oneself and I feel bad about sending out stuff that is not correct.

I would be happy for you to post the problems here as you find them and that way the other people to whom I have sent plans can see and either correct them or ask for an amendment.

So press on my friend, and let it all hang out.

Regards

Jim


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## Jeff-in-PA

I PM,d about a set of plans too.  Thanks

 Cheers
   Jeff


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## GKNIPP

With your blessings Jim I will begin to post as I find errors, missing features/dimensions etc....

Sheet #4  "Rear Plate",----- Should there be a relief or cut-out to allow for clearance of connecting rod ?

Sheet #5  "Governor Side Plate",----- The upper hole feature located towards bearing block cut-out missing dia./thread size.

Sheet #6  " Ignition Side Plate" , ----- The hole for cam gear shaft is marked as 3X and should be only 1X.  Should the X&Y dimensions for this hole location be given using the crank center as datum by the utilization of the pitch dias. of gears for proper mesh?

Sheet #7   "Crankshaft"------ Missing center distance of crank throw from main shaft dia. and hidden line indicating the crank throw dia.

Sheet #18  "Exhaust Rocker"------Missing "L" shaped finger depth dimension from centerline of part to tip of R4.

Sheet #19   "60T gear & 30T gear"------ Is it possible to list the root diameters, outer diameters and pitch circle diameters of specified gears.

Again Jim, Please do not look at this as me being a pain but rather trying to be helpful.  I am sure I can speak for the rest of the guys that your work is well appreciated.

This is all for now.  My wife suggests we get some supper now.

Regards my friend;

Greg


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## AussieJimG

Thanks Greg, you are doing a great job. I will fix the drawings today. I am sorry I made it so hard for you.

Jim


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## GKNIPP

Not hard at all.  It is easy enough to do, in fact, I can't guarantee I didn't overlook something but I hope not.    It is just greatly appreciated that you took the initiative to share a design with us as you did the hard work.

Sheet #21  "Valve Rod"-----  Thread length dimensions missing at each end of rod.

Sheet  #22  "Flywheel Center"------  Add note suggesting to install bolt hole pattern in cenetr after assembled so as to insure proper orientation of mating part #80, governor plate, to position weight arm BETWEEN spoke of flywheel assembly.

Sheet #24   "Governor Adjuster" -----  I believe the 10mm center hole should be indicated as a 10mmx1.0 thread?


Well, I think that is about all I can detect for now.  Now comes the fun part!!!!  C O N V E R S I O N!!!!!!!!!

Thanks Jim;

Greg


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## GKNIPP

Jim, I do notice that the drawing set does not include the following parts:

-No Carburator Parts---- #110, #111, 

-No Oiler Parts---- #119, #120, #121, #122, #123, #124

-No Grease Cup Parts----#117, #118

-No Muffler Parts----#106, #107, #108, #109

See I told you I would overlook things too.  I realize the oilers and grease cups coulds easily be purchased and the if the modeler chose to do so he would need to adapt the engine parts to suit.

Greg


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## AussieJimG

Hi Greg, I finished amending and adding drawings after a long day yesterday and opened my email this morning in fear and trepidation (not really) but there were no more errors (?).

Just a couple of things: Sheet 4 Rear plate cutout. There was one on the original and I put one on mine to accommodate an oiler on the big end bearing cap. But my engine kept snapping the oiler off and throwing it across the workshop (never did find one of them). Then I found that there is so much oil splashed around from the piston that the big end seems to be adequately lubricated anyway. So I omitted the oiler. The conrod does not touch the end plate so that is not a problem. The cutout could be included for cosmetic purposes if required but I think the blank end might stop some of the oil being thrown so far.

Sheet 19 Gears. I could not find the root diameter for the gears. I think anybody making the gears will be able to obtain the dimensions from the specifications. Outside diameter and Pitch diameter were added as requested.

Sheet 21 Valve rod. The little down arrow is intended to indicate the length of the thread. I tried to add an explicit dimension but it didn't "take". Sorry about that.

I have sent you a set of all the updated drawings. 

Bertil, BC1, Ian, Ken, Lonnie, I have also sent the updated drawings to you. Please let me know if they arrive safely.

Cogsy, drawings have been sent but they have overloaded your inbox. Let me know what did not arrive and I will send it again.

Leonard, CD going in the post today with complete set of updated drawings and other stuff as requested.

Once again Greg, thank you for all your efforts. I am astonished at how much I had left out. And good luck with the conversion.

Anyone else need the updated drawings?

Jim


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## ozzie46

I'd Like a set too please. PM sent.

   Ron


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## bearcar1

Drawing updates arrived this afternoon in good fashion Jim, thank-you for keeping me(us) in mind. I've sent you a private email as well. All the new pages have been accounted for and replaced in my files, along with the addendum sheet for future references. Well done.

BC1
Jim


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## AussieJimG

Jim (BC1) has noticed that Sheet 24 is still Revision 1 and does not show the thread on Item 99. Thanks Jim dunno how I missed that but it is now fixed in the drawings and in the amendment sheet.

Would you and the rest of you to whom I sent the amendment sheet please hand amend Sheet 24 to show Item 99 with an M10x1.0 thread in the central hole and change the revision to 2.

And Cogsy and Leonard (who got the works) please do likewise.

Ron (ozzie46) yours should be ok when they arrive.

And other problems, please let me know. We might as well get it right.

Regards

Jim


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## aarggh

Hi Jim,

I got the updated drawings thanks very much! And thanks to Greg too for his valuable input!

cheers, Ian


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## Cogsy

AussieJimG said:


> Cogsy, drawings have been sent but they have overloaded your inbox. Let me know what did not arrive and I will send it again.


 
Thanks Jim, I got everything except the sheets 21-31. Looks great too Thm:


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## ozzie46

I want to publicly thank Jim for the drawings. I received all of them. 

Thanks Jim.

 Ron


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## AussieJimG

Last file (Sheets 21-31) is on its way Cogsy

Thanks everyone for your interest.

Jim


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## GKNIPP

Once I get these converted, I am going to need to harness someones abilities to transfer the dimensions onto the CAD prints. 

BTW, where do you guys go to purchase gears?  I used to have a suppliers list but cannot locate it at this time.  

Thanks to everyone for your patience;

Greg


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## AussieJimG

Is anybody still waiting for copies of the drawings?

Jim


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## AussieJimG

I feel sure I will regret this Greg, but if you can't find anybody else to transfer your inch dimensions to the CAD, send me the marked up drawings and I will do it.

Jim


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## GKNIPP

Thanks a million Jim!!!!  Your the best.

Greg


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