Kiwi Mk2 Engine

[vcutajar]

I then located the 10mm crankshaft hole I had in the timing cover and opened it up to 11mm using an 11mm slot drill.

 

[vcutajar]

I have been working on the camshaft bushes. I used a piece of bronze that came with the kit and turned both bushes. I then drilled and reamed a 5mm hole in each bush and then pressed both bushes in their respective places. The long bush in the timing cover and the short one in the crankcase. I don't have a press so used the mill to press the bushes.

 

[vcutajar]

And both bushes pressed in place. I fitted the timing cover to the crankcase to check if a piece of 5mm silver steel passes through both bushes. No problems.

 

[vcutajar]

I made the shaft which holds the cams and gear as per plan except I used a 6mm rod and turned the ends 5mm (photo 1). Well, it has to be remade . The central 6mm part is about 1.2mm short and the 5mm end which will hold the ignition cam is about 2 or 3mm short. Could it be a mistake in the dimensions? I'm not really sure and I did not bother to investigate. Good thing I noticed it now.

Instead of remaking the shaft I made the hole which takes the tappet guide. Hand fitted the tappet guide to be a tight fit and drilled and tapped the 3mm holes which hold the tappet guide to the cylinder platform.

Tomorrow I'm off to Munich but whilst there I will study George's tutorial on making crankshafts. Most probably that will be my next item. I will also need to figure out how to make a 2mm keyway in a 6mm hole ???. Any suggestions? scratch.gif

 

[vcutajar]

Finally back home from freezing Munich. Whilst there, I decided that the next part to be made (actually attempted) will be the crankshaft. I had a good look at George's tutorial about making crankshafts and got a couple ideas from the tutorial (http://www.homemodelenginemachinist.com/index.php?topic=5673.0). I will be making the first attempt from flat barstock that came with the kit. If that fails, then I will try and fabricate it. Both methods are described in Westbury's article.

First order of the day is to make the tool to turn the crankshaft. It has to have a reach of at least 1.25". I have an HSS parting tool that I have never used (see photos) and was wondering if it's a suitable candidate to transform into a bifurcated tool. The tip of the parting tool is 5mm wide and the lenght of the crankpin is 12.7mm. What do you think? ???

 

[vcutajar]

Started attempt No.1 on the crankshaft. Used the flat bar which came with the kit and scribed some lines on it. The lines are not very visible in the photo. Also started grinding the crankshaft turning tool from the parting tool.

 

[Mainer]

I think I actually did make the Kiwi crank from the solid. The next crank I did for another engine -- still in progress -- was built up using Loctite and pins in the joints. All in all, I think a built-up crank is easier, but I guess one ought to make a solid crank at least once just for the experience.

 

[vcutajar]

Hi Steve

Hope you are well.

I am doing the first attempt of the crankshaft from solid because I have the material. If this does not work out then it will be fabricated.

Vince

 

[vcutajar]

Continued grinding the parting tool and finally finished it. Did some test cuts with it and had to set it below centreline to avoid chatter and to give a decent cut. Not really happy with it but I guess it will have to do for now.

 

[vcutajar]

Centre-drilled the sides of the bar for the live and dead centres then chain drilled the inside of the webs. Used a hacksaw and coping saw to remove the material. Most probably later on I will mill the inside of the webs to clean it up.

 

[metalmad]

HI Vince
just take it slow mate and u will have a winner for sure
Pete

 

[steamer]

Hey Vince,

Just take your time...Pete's comments apply!

Dave

 

[vcutajar]

Hi Pete and Dave

I didn't realise I was that fast. Actually I had the impression that I was slow. I need to heed what an old (now retired) work collegue used to say AUSE.

Vince

 

[vcutajar]

Cleaned up the insides of the webs on the milling machine. Set it up in the lathe between centres. Used a live centre in the tailstock and a dead centre in the headstock spindle. Bolted an 8mm threaded bar in the chuck backplate and fixed the part to be machined between centres with a nylon tie-wrap. Started machining the crankpin but stopped at 10.1mm. Next time I will continue machining the crankpin to 9.95mm.

 

[vcutajar]

Finished the crankpin to dimension. Started work on one of the main journals. Chain drilled and hacksawed the excess material. Inserted a brass packing piece inside the webs and just to make sure it does not fly off I secured it with a nylon tie-wrap. Drilled and tapped 6mm a hole on the side and screwed in a 6mm bolt. Put the piece between centres and secured the bolt with nylon tie-wrap (third photo). Turned down to 10mm and then the end was turned down to 8mm. To turn the 8mm section I had to change the live centre to a half dead centre as the tool was fouling with the live centre.

One side finished but the sides of the web turned out a bit rough. Most probably when doing the other side I will mill the sides of the web first before putting it between centres.

 

[vcutajar]

Chain drilled and hacksawed the other side for the other journal (photo 1). This time milled the outside of the webs (photo 2). Put it in the lathe but instead of between centres, I held the part in a collet and the other side with a live centre (photo 3). Same as the other side I had to change the live centre to a half dead centre for the final 8mm cut. And this is how it looks after lathe work was finished (photo 4).

 

[vcutajar]

Crankshaft is not finished yet. I threaded the ends of the shaft 8mm fine (1mm pitch) with a die. The plans do not specify the lenght of the threads so I made them short and will increase as required at a later stage. The top and bottom of the webs need to be rounded off but I intend to do that when the bronze counterweights are in place. Also I need to drill the oil passageways. I will be drilling them 2.5mm and then tapping 3mm. Yesterday I went shopping for a long series 2.5mm drill which I could not find so I settled for an extra long version. Hope I do not break it in the hole.

 

[Blogwitch]

Vince,

That is indeed a very nice crank you have made there, perfectly to the book.

I have one to make, maybe a bit later this year, but about four times the mass of yours, and it will be made by exactly the same method.

Well done for showing us all how.


John

 

[vcutajar]

Thanks John for the compliment. My first attempt at crankshaft turning seems to have been a success. We still have to see if it actually does its intended job properly.

Vince

 

[vcutajar]

This evening I fitted the crankshaft in the crankcase and tried to turn it by hand. It was binding at a particular angle. Took the crankshaft out, put it in the collet which was still fitted to the lathe and started the lathe. There was a slight wobble at the end which was confirmed with a DTI. I suspect that the brass packing I put between the webs was too tight. Lesson learnt.

Using the DTI and a plastic hammer the crankshaft was trued. Tested again in the crankcase and it was much better. Gave it some running in on the lathe (photo).