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发动机建造 Kiwi Mk2(绝对精华)

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 楼主| 发表于 2014-4-22 04:46:57 | 显示全部楼层
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.

发动机建造

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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.

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 楼主| 发表于 2014-4-22 04:47:44 | 显示全部楼层
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.

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 楼主| 发表于 2014-4-23 04:31:21 | 显示全部楼层
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.

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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.

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 楼主| 发表于 2014-4-23 04:31:46 | 显示全部楼层

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 楼主| 发表于 2014-4-23 04:32:12 | 显示全部楼层
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 thefront and back thickness to the required dimension and most probably this evening I will re-mark it and take the angled cut.

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 楼主| 发表于 2014-4-23 04:33:00 | 显示全部楼层
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.

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Filed the back and bottom contour and sanded the arms. Removed most machining marks. Some still evident in the main body recess. Just could not remove them. Polished with a dremel to a shiny finish. At one time, rocker arm literally flew from my hand whilst polishing. I am not going to repeat what was said at that time. Took me 30 minutes to find it.
8 days to do two rocker arms.

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 楼主| 发表于 2014-4-23 04:33:31 | 显示全部楼层
Today I started work on the rocker arm bushes. E.T. Westbury specifies that these should be made from gunmetal (yellow brass) and not from brass. Now I have never used gunmetal so I do not know how it looks. I have found a piece of hexagonal bar (in the kit) suitable for the bushes but I suspect its brass and not gunmetal. Well, if this engine ever runs, I would be running for short periods so I guess if the bushes are made of brass, it would not make a lot of difference.
I faced of the hexagonal stock and it felt like brass. I then turned it down to 6mm diameter. According to the plans it should be the same thickness as the rocker arm, but I made it a tad longer as I suspect that the rocker arm might bind with the rocker arm pillar. I can always shorten it later on. I parted the part off and faced it.
Hopefully tomorrow, if I manage to find the 3mm reamer, I will drill and ream the bushes. It has to be drilled 1/64" off centre.
Now to continue babysitting the cats and make myself something to eat as I am alone at home (wife and kids went for a 3 day holiday in Rome).

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 楼主| 发表于 2014-4-23 04:34:20 | 显示全部楼层
After a long search this morning for the 3mm reamer I still could not find it. It was made by Master and I love their tooling. Unfortunately the shop that imported them from Italy does not get them anymore because since they have been taken over by Scandvik they could not handle the relatively small orders (very small market locally). So I got myself a Dormier reamer. Hope its OK. We'll find out later on today.


The Dormier reamer worked out fine. Drilled the hole 1/64" off the centre and reamed it. Trial fit in the rocker arms and all seems OK. Most probably will do the 3mm studs for the bushes.

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 楼主| 发表于 2014-4-23 04:35:08 | 显示全部楼层
Did the 3mm studs. Just took 3mm bar stock and cut it to lenght. There where no dimensions on the plans but it was easy to figure them out. Threaded both ends and that's all. The second photo shows my method of keeping the die straight whilst threading. I just use an old collet chuck in the tailstock.
I was thinking I would do the rocker arm pillar next but I would not be able to complete it before the cylinder head. I do not like to start parts that I cannot completly finish so am trying to see what else I can do. I was hoping that by this time I would have received the timing gears, but they still have not arrived. Last week I sent an email to Kirk at Hemingways to check about these gears but have not received any response. Usually he is quick in answering back. I suspect that Hemingways may be closed due to the festivities.
I guess I am stuck.

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 楼主| 发表于 2014-4-23 04:35:53 | 显示全部楼层
Today I found something else I could do on the engine. I started work on the crankcase breather sytem. I started off with a 12 mm brass bar stock and turned it down to 10.5mm. I then knurled the machined part and then continued turning down part of the knurl to 6mm. I threaded it 6mm Fine with a die. I then made a quick 6mm fine nut out of a piece of brass strip. I cut a shallow groove at the top of the thread (between thread and knurl) and inserted the thin nut I just made to clean up the thread. I left it there and reduced the thread lenght to dimension using the nut to clean the edge of the thread.
And that's when the lathe motor started giving my problems (see other thread). This evening managed to fix the motor and finished the cap of the crankcase breather. I will not part it off for now just in case it needs further machining. Next I will work on the breather body.

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