Kiwi Mk2 Engine

[ShedBoy]

I thought you would keep the chucking spiggot until the back crankcase half was bored to keep it concentric? Is a mandrel used to do this?

Brock

 

[vcutajar]

Now that's an idea I did not think about. Oh well, too late, the chucking piece is gone now. Actually, that's what Westbury does in his article. He removes the chucking piece and starts work on the other part of the crankcase and that's where I get lost because I can't understand how he gets both crankshaft holes aligned. Maybe I need to read between the lines.

So when I start work on the other half that's where I will deviate from the magazine article. I have a couple of ideas ..... Let's see when I get there. Wish me luck.

 

[Mainer]

I don't remember how I did it. I do remember I flattened off the back face by rubbing the casting over a piece of aluminum oxide paper lying on my surface plate. It then got chucked in the 4-jaw, and I "centered" (if you can call it that) the casting by getting the bosses for the bolts that hold the crankcase together to be as much as possible on the same pitch circle when I rotated the casting, leaving the center of the casting to take care of itself (though I must have checked it, a least a little). Then I must have turned the chucking piece...and from there on it gets foggy.... ;D I have no recollection of how I got the other half of the crankcase to line up. I may have turned the mating flange on the 2nd half of the casting so the two would be aligned, then drilled the bolt holes in one half and spotted the locations of the holes in the 2nd half. Or something....

Personally, I enjoyed the challenge of finding the parts inside the castings. The thing I didn't like was the ever-present fear of screwing it up and having to buy another casting for a not-insignificant amount of money.
Several times I would do a setup, then walk away for a while before I came back and re-checked the setup for errors before cutting anything.

 

[vcutajar]

The thing I didn't like was the ever-present fear of screwing it up and having to buy another casting for a not-insignificant amount of money.

Mainer, I know the feeling and by the way those photos you had sent me are a godsend. I very often look at them to see how a part looks. There is not much info or images of the Kiwi on the internet

Vince

 

[vcutajar]

This morning I went to the garage and as the chuck was already off the spindle I decided to check the alignment of the tailstock to the headstock. So, out came the parallel test bar. Took readings and everything was OK. It must be the 3 jaw chuck that is the problem because if I ream a 10mm hole it always ends up 10.2mm. Oh well have to work around it.

Started work on the crankshaft bush for the front crankcase. Used a piece of bronze from the kit. Turned it 12.7mm and gave it a 1.6mm lip of 15.8mm diameter. Parted it off and cleaned it up. Put back in the chuck and drilled 9.8mm. Now I am not going to ream it because it would end up oversize so the solution was to bore it. only problem was that I do not have such a small boring bar. After rumaging trough the tools I found an small imperial internal threading tool which I do not use, ground it out further to make it even smaller and now I had a small boring tool. Worked like a charm. The hole was bored 10.05 mm.

 

[vcutajar]

I then pushed the bush in the cranckcase body and tried it with a 10mm silver steel rod. Good fit. I haven't pressed the ball bearing in yet as I still have some work to do and I do not want to contaminate it with aluminium dust, but seems to work also with the bush.

Last photo is my improvised boring bar.

 

[vcutajar]

Did not do much today. Not that I usually do a lot. Morning was spent at the annual get-together at the radio amateurs club.

This evening drilled and tapped (5mm) the hole for the oil drain plug and inserted the bearing. Trial fit with a 10mm silver steel rod was ok. Then I started work on the timing cover. Machined on the lathe the outside face and reversed it to machine the other side, but the tool bit was getting too close to the chuck jaws, so I stopped for today.

Next time I have to figure out how to continue work on the timing cover.

 

[vcutajar]

This morning spent most of the time figuring out how to continue work on the timing cover. At first I was thinking of putting a spacer under the cover in the chuck to take it out some more but at the end discarded this idea as I thought it would would be dangerous if the part flew out of the chuck.

So at the end I ended up using the same method I used for the tappet guides; i.e. fixing the cover to another piece of aluminium and using the rotary table. I figured out that in just one setting I could first reduce the diameter of the cover, then reduce the thickness of the cover and at the end machine the edge recess.

I only managed to get it fixed to aluminium using two 4mm brass screws. Will continue next time.

 

[vcutajar]

Continued work on the timing cover. Centred it in the rotary table and marked out the desired diameter. Then started milling out the edge with an 8mm endmill. After finishing the diameter I wrote down the DRO X axis reading (2nd photo) which will come in handy when machining the edge recess. I then milled the part to the required thickness.

Next time I will work on the edge recess. Before switching off the DRO I brought back the X axis to zero (Y axis already at zero) and reset the Z axis to zero.

Tomorrow back to work (real work).

 

[vcutajar]

Good news. The missing parts from the kit, namely, the timing gears, piston casting and a piece of spring steel arrived today. Had a look at the timing gears and I see that they still need further machining which should not be a problem. The good thing was the the bore was small so I can enlarge it as much as I want to go metric. Stored them away in the box with the rest of the parts. Hopefully I will come to the stage where I can work on them.

Continued work on the timing cover and machined the recess. I made the recess a little deeper (smaller diameter) as with the original dimensions I was afraid that the wall of the matching recess on the crank case was going to be too thin. Also I noticed that the depths of both recesses (according to plans) were not the same. If I leave them like that the cover would only be supported on the thin wall of the crankcase. Most probably I'll make them both the same size for better support.

Tommorrow I'll plan to finish work on the cover by replacing the 4mm threaded holes with 4mm clearance holes and machine for countersunk screws.

 

[willburrrr2003]

Looks like your having fun with this project! I have enjoyed reading your progress up to this point and look forward to seeing more and the finished Engine :bow:

Regards,

Will R.

 

[vcutajar]

Thanks Will.

and the finished Engine

That is still debatable. I have made models before (not engines) but always from bar stock. This is my first engine and also my first casting kit. It is still a learning experience for me and hopefully if I manage to get past the crankcase (which I feel is the most difficult part in this kit) the rest is all downhill.

Vince

 

[vcutajar]

Today finished work on the timing cover by drilling the 4mm holes and coutersinking. I first screwed in the tap in the threaded hole, chucked the tap and brought down the chuck until the cover just touched the table. Clamped the cover, replaced the tap with a 4mm drill and drilled the hole. Then I countersunk the hole with a 8.3mm countersink tool.

Timing cover finished for now.

Time to vacuum and clean the mill table and rotary table.

 

[vcutajar]

The next operations on the rear part of the crankcase is where I am going to deviate from the instructions in the article. This is either going to make or break the project. Wish me luck.

I skimmed the side where the timing cover sits. And then I stopped to meditate on the next steps. Need to sleep on it before I continue.

 

[vcutajar]

This morning, after sleeping on it, it was decided to continue work on the rear part of the crankcase (sorry no pictures today as forgot the camera in the garage).

I first put both halves of the crankcase together in my bench vise (with soft jaws). I lined up the outside of both halves as much as I could by eye. Used a couple of toolmaker clamps to hold it together and took it out of the benchvise to have a better look at the line up. I had to do it a couple of times before I was satisfied.

I then took a piece of 10mm silver steel and turned one end 45 deg to make a temporary punch. Put the punch through the front half which was a nice fit, and marked the rear side on the bearing housing. The the plan was to put it on the rotary table for facing and creating the recess for the front half spigot, but could not find a suitable way of clamping it properly. So after much fussing about it was time to try the 4 jaw chuck on the lathe.

Unfortunately, the piece of the casting I wanted to chuck has a slight taper, so pieces of marine three-ply wood were inserted between the jaws and casting so that it could grip the casting better and also avoid scoring the casting with the jaws. Eventually the casting was lined up with the punch mark I had done earlier and the face was trimmed off to dimension. Then the recess was machined and a trial fit was attempted with success. Nice fit without any slop. Hopefully tommorrow I will face off the bearing housing.

 

[vcutajar]

Here are the photos of yesterdays work:

Photo 1: Temporary Punch
Photo 2: Crankcase clamped in bench vise and toolmaker clamps
Photo 3: Crankcase with toolmaker clamps and temporary punch inserted (ready to be whacked with a hammer )
Photo 4: Casting in 4 jaw chuck with marine ply.

 

[vcutajar]

Today I faced off the bearing housing in the casting but left it 1mm higher for further machining when machining the bearing hole. Took it out of the chuck and made a trial fit with the mating casting. Not bad.

Next operation was supposed to drill and tap for the 6 bolts which will hold the crankcase together but am having second thoughts. On the plan it specifies 4BA which I was going to replace with 4mm ( which I already have ) but I suspect that would be cutting it too tight for the bosses (especially one of them). So I was thinking of using 3mm bolts instead. What do you think? Which is the best replacement for 4BA, 4mm or 3mm? As it is, I don't have all the 3mm bolts available and I am working this weekend so I doubt there will be any progress in that area which will give me time to ponder this dilemma.

I might instead cut the recess for the timing cover and get that out of the way.

 

[vcutajar]

Well the weekend has nearly passed and only today had time to work on the Kiwi. I only managed to cut the recess for the timing cover and mill the bottom to the correct depth. I did not have time to drill and tap for the two 4mm countersunk screws of the timing cover. I spent a lot of time trying to line up the casting on the rotary table trying various methods but never being happy with the end result. Finally, after nearly giving up, I had one of those moments.

I am a bit hesitant (ashamed really) in describing it here, but it did work, so here goes. I chucked the timing cover in the 3 jaw chuck and using a pointed tool in the tailstock, lightly marked the center. I put the cover on the casting, centering it by eye, and taped it up with masking tape. Put the casting (with taped up cover) on the rotary table and centered it using the center mark I had on the cover. Clamped it tight, removed the tape and the cover and machined it. I must have been lucky because it worked well.

I think I have also decided that I am going to use 4mm bolts with allen heads for the crankcase bolts.

 

[vcutajar]

Today I drilled and tapped the two holes for fixing the timing cover to the crankcase. I usually insert the tap in the chuck and start the first few threads by turning the chuck by hand and then continue with the tap wrench.

Timing cover is now attached to the casting. I also faced off the bosses on the front crankcase casting in preparation to drilling.

 

[vcutajar]

Drilled the front crankcase casting for the six 4mm bolts. Attached both parts of the crankcase castings and secured it with a clamp and using a transfer punch marked where one hole needs to be drilled and tapped 4mm.

Now, I do not have a transfer punch set, so what I did, I ground the back of a 4mm drill and used that with a plastic hammer to mark the casting.

Once I drilled and tapped the first hole, I mated the castings together again, this time using a 4mm bolt to hold them together, and using the same homemade transfer punch, I marked where the other holes need to be drilled. Two holes drilled and tapped and four to go.