I am going to continue this build but using smaller pictures otherwise it could get very boring scrolling thru it all. I will be bouncing from one machining operation to another, if you don't understand anything then just ask, and I will give you as much info as I am able.
I will be showing how I get things done with tips on how I do it, and sometimes the reasons behind why I do it that way. Your way may be different, but if we get to the same conclusion, who cares, we are here to make little engines.
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I showed you last time that I had marked out the large vertical uprights, this next pic shows that I have cut them out using my little B&D upright bandsaw.
Now what I have done with these is to stick them together with double sided tape. This will allow me to machine them all to the same size. This technique works as long as there are no free blocks outside the grip of the vice jaws. This will be self explanatory over the next couple of pics.
This and the next pic are not very good, but they do show that the blocks are held together by the vice jaws, the tape stops them moving about when they are released from the jaws. This shot shows the second side being fly cut after the first side was faced and is now tapped down onto a parallel (in this case a 1-2-3 block). These faces are machined down until the correct width is reached. By having them stuck together allows you to take them out as a solid block for measurement.
On this shot I am squaring up the end of the uprights (If this was a solid block rather than laminations I would just pop it into my four jaw and face up using that, it gives a much better finish). But I only do this on one end. It is then deburred and put down in the vice onto paras, and the top face is cleaned up with a flycutter. The job is then turned over so the just flycut face is now down onto the para and the upper face is then flycut to give the correct height. There is a reason for doing this, a couple of extra minutes spent flycutting will save hours on cleaning up the edges by hand, as when faced up with an endmill the finish is never really as good as a flycut face.
Here are the six required plates, machined to size with nice mirror finished edges. It is a shame that they will have to be removed, except for the bottom, when the plate is profiled, but doing it this way will ensure all the holes are in the right places.
What I have done is marked a corner on each plate, this is the datum corner, so when the machine is set up to drill, the plates are placed into the vice in the same position. This will ensure the side and end holes are all in the same position to each other. Here is showing using the edge finder to get the edge of the plate so I can then position the drill to put the bearing hole thru. The table is then locked up solid. You will also notice I am using a backstop. This allows me to drill a hole, replace the plate and drill a hole in the same position on the new plate. It is the only way to go if you are making multiple parts.
The bearing holes have been drilled and deburred and are now down in the chuck jaws and I am edge finding again to find the location of the tapped and dowel holes. Again everything is locked up and the backstop used for locating the new part.
Here are the three finished pairs of uprights before profiling. I have decided to use roller bearings in them, but just plain holes will do as long as they are a nice sliding fit and not too loose, and a bit of lube is used, the choice is your own.
Now you ask, what is the dowelled hole for? I am a cheapskate, so if I can get away without using something I will. Normally you would use two screws to hold the upright to the baseplate, but in this case, even a small screw would be plenty strong enough to hold it, so what I have done is just put another hole in the bottom of the upright, and a matching one in the baseplate will have a little bit of rod put in there and this will be a location point to stop the upright moving, and the screw secures it to the baseplate.
Thats it for this post. If you are finding it boring or uninformative just let me know and I will stop.
If not, I expect to have these engines to a running state by early next week.
The medicos got at me this morning so I just might be going a little slow for a day or two.
John
Finger engine
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