Kiwi Mk2 Engine

[vcutajar]

I then cleaned up the tappets and hand fitted the tappets in the tappet guide.

 

[vcutajar]

This evening decided to start work on the rocker arms. Using a lenght of 10mm x 10mm BMS to cater for both rocker arms. Started milling the bar to dimension. Finished three sides only. Tommorrow will continue on the fourth side and hacksaw it in the middle.

 

[vcutajar]

I see now that I am an advanced member. Must be something to do with the number of posts. I also see that somebody gave me a karma point. For what I don't know. Whoever it was thanks.

Today I continued milling the fourth side. I then marked the lenghts of the rockers and hacksawed the excess. Filled the parts a little closer to the line and then milled off the sides. Ended with two pieces of BMS for the rockers ready for further machining.

 

[vcutajar]

Shucks guys, another two karmas. Thanks to the karma givers but I haven't done anything special up till now. Guess I am doing something right.

This evening continued on the rocker arms. First I drilled the oil hole for the shaft by using a 1.6mm centre drill. That means I drilled the holes and coutersunk them in one operation. Next I drilled the 3mm holes for the pushrods using a 3mm ball nosed mill. As these holes are off the centreline it will help me keep track of which is the front and back of the rocker arm.

Spent nearly 2 hours on these 4 holes. Good thing I am not on a production line!

 

[vcutajar]

This morning continued work on the rocker arms. At first I was thinking of drilling the 6mm hole for the shaft that goes through the rockers but then I thought that when clamping the rockers for further work I might bend or squash the hole. So no holes for now and decidedm to start reducing the side faces as per plans. The plans also show the cuts to end with a radius but no radius dimensions a given. Using a radius gauge I estimated that 1.5mm radius should be close enough. I could have opted to do with without a radius but decided that as this part was visible, a radius cut would be nicer.

At first I thought I would use the faceplate and use a profile tool that I have but when I checked the tool it had a diameter of 6mm. Too large. Faceplate method went out of the window. My other option was the rotary table and use a 3mm ball nose mill. Out came the rotary table and it was located on the table. New problem. How am I going to clamp that small piece of steel to the rotary table. After a bit of head scratching I remembered I have a small 25mm pin vice. Would this work? There only one way of knowing and that is by trying it out.

Marked the centre of where the hole should be and clamped it in the pin vice. Put the vice on the table, located the crosshair (a bit fiddly) and clamped the vice on the rotary table. Reset the DRO x and y to zero so that I do not need to locate the rotary table again and with a scriber in the collet marked the sides of the cuts by displacing the y axis the required amount.

 

[vcutajar]

Started the outer cut and brought it down to required depth using light cuts (0.1mm). The plan was that then I would do the inner cut and then clean up the middle with an end mill. But as usual this plan changed. When I finished the outer cut I started going inwards slowly in 0.1mm increments using the same 3mm ball nose cutter. Don't ask because I can't remember how many times I turned that hand wheel. Eventually I finished. Three sides still to go. Maybe this evening I will do the opposite side. The cut has to be twice as deep as the centreline is offset.

 

[vcutajar]

This evening I did the other side and now I can't feel my arm. Maybe tommorrow I will start on the other rocker arm but I doubt that I will do both sides.

 

[vcutajar]

Today finished profiling the other rocker arm. Good thing its not a V12! Now I think its safe to drill the 6mm hole for the shaft before I continue machining the top and bottom of the arms.

 

[vcutajar]

Today I could not resist the urge so, I drilled and reamed the 6mm hole for the rocker arm shaft. Now to figure out how to continue profiling the top and bottom of the rocker arms.

 

[ShedBoy]

Nice work, the Kiwi is a classic and yours is shaping up the same. Great thread.

Brock

 

[vcutajar]

Thanks Brock.

Wish me luck as this is my first ever model i.c. engine and I am keeping my fingers crossed all the time. I am trying to keep this thread similar to a diary. I jot down whatever I do or think of doing on this model.

 

[vcutajar]

This morning I worked on the front part of the rocker arms. That part which pushes the valves down. Does it have a technical name? Well, it calls for a radius. So I marked the edge of the radius, put both rocker arms in the vice and milled off the excess material keeping just shy off the mark. Removed the vice, installed the rotary table and using my trusty 25mm vice located the origin of the radius under the spindle. Then using a 3mm endmill I cut the radius to the desired dimension (4.76mm). Easier that I thought it would be. Maybe this evening I'll continue working on the front part of the rockers.

 

[Mainer]

You're doing well.

When I made Kiwi, I ended up making 7 rocker arms before I got two good ones. (The extra five were "learning experiences." ;D )

 

[vcutajar]

Hi Mainer

Well my two rocker arms are not finished yet. Things can still go horibly wrong. I am using your drawing you sent me of the rocker arms and also the photos you sent.

 

[vcutajar]

This evening continued working on the front part of the rocker arms. The angled cuts were just eyeballed. Tomorrow will start work on the back part of the rockers.

 

[vcutajar]

Started off today by drilling a 3mm hole with a slot drill. I then milled the excess material. I then cleaned it up by milling.

 

[vcutajar]

And the first photo is the result of the previous operation.

I then decided to mill off the angle on the top part of the rockers. Marked it off and put them in the vice then realised that if I take the cut it would be difficult to do the next operation. So instead I reduced the front and back thickness to the required dimension and most probably this evening I will re-mark it and take the angled cut.

 

[John S]

This morning I worked on the front part of the rocker arms. That part which pushes the valves down. Does it have a technical name?

Don't know how accurate the description is but I have heard of heel and toe.

John S.

 

[vcutajar]

Thanks John

Heel or Toe. If you think about it, it makes sense. Good, learned something new today.

 

[vcutajar]

This evening re-marked the angle at the top of the rockers and milled it.

Tommorrow it's going to be an armstrong session (filling, sanding and polishing) and not looking forward to it, but if I don't do it immediately after I finish a part, then it never gets done.