Today I spent quite a bit of time on working out the co-ordinates for drilling then reaming the holes in the cylinder block for the 8 valves and 4 cylinder liners. It’s critical that measurement should take place from a machined surface and I choose the right hand side face when looking at the photo of the cylinder block on the milling table. I had previously set the casting parallel to the X axis by using the two plugs centre drilled previously.
I normally use my electronic edge finder that lights to show contact, and therefore the edge (after allowance for ½ the diameter of the end) of the part being measured. However the overhang on the edge finder would not allow measurement and I do no possess any slip gauges or the like so I made use of the ‘wiggler’ set I used before buying the electronic edge finder. It was quite nice to revisit an old friend as it were and the edge was fed into the digital readout, after allowance for the ½ diameter.
Because the cylinder block is a substantial casting and the critical nature of making sure the valves, cylinders, camshaft etc. line up, I made several movements to see that the end co-ordinates looked correct. It was during this exercise that I found the co-ordinates wouldn’t work in relation to the 4 holes already there for the pistons.
(above is supposed to be the centre of the 4th bore!)
When checking the dimensions against the other recently bought set of castings, I found yet again that my casting was significantly larger. So I decided to center the mill over the nearest cylinder hole to the datum face and confirmed the ‘extra’ distance. So after recording the measured difference in case it is needed later, I reset the DRO to zero and carried out the checks for the co-ordinates again. This time everything worked out fine and I decided to center drill the 8 valve stem holes. Then it was the turn of a 15/64” drill before reaming with a ¼” reamer.
The remainder of the session was spent adjusting the belts of the milling machine to reduce speed for boring and a start made on the first cylinder bore. However at the beginning of the next session I will make a plug of the correct size to use as a set standard for all four bores. Whilst each cylinder liner can be ‘adjusted’ to suit I would like to get them as near as possible to the correct size so I can produce the 8 cylinder liners as a batch. After all I should seek to increase my engineering skills, and accuracy is a measure of progress is it not.
Overall a good session with the many checks proving of worth, even if there was not a great deal of swarf made!
About Mike Freeman
Hello, my name is Mike Freeman and I am a retired Chief Fire Officer from the United Kingdom with a keen interest in model engineering, silver caddy spoons and sea fishing. I live in the pretty fishing port of Brixham, South Devon, in the United Kingdom.
I am a sufferer of degenerative osteoarthritis, which impacts on the amount of time I can spend in the workshop, and is the reason why you will see seats and a stool in some of the photo's. I have only recently added the above sentence after a discussion with one of my Doctor's from the excellent pain clinic, based in Torbay. This does affect concentration one of the reasons why I double then re-double my measurements and set ups.
Before completing nearly 30 years of public service I and my wife Sandy, owned and ran, a small restaurant in Okehampton Devon. Prior to marriage I worked for my father in his various businesses, in the early days these were garages, which he bought in a run down state, then built them up before moving on, to start again.
I took every opportunity in those early days, to work in his workshop's
learning 'on the job' rather than as an apprentice. This, I suspect, is the reason why my building various model's in the early days, turned into model engineering, when funds allowed the required equipment to be bought.
My workshop comprises one half of a detached double garage. It has a
stud wall separating the two halves and unusually perhaps, its own
shower/toilet/washbasin compartment! (the true reason for buying the
bungalow - don't tell the wife!!!)
It is fully insulated with a ceiling and fluorescent lighting supplementing the one window. Several double electrical sockets are dotted around in
relevant positions.
Equipment consists of 2 lathes (1 Myford ML 10 and 1 Chinese variable
speed motor with etched glass DRO's), 1 milling machine (RF25 far East) floor standing pillar drill, Proxxon bandsaw, Warco bandsaw, 6" wire brush and polishing mop motor, 6" coarse and fine grinder, Proxxon mini drill, various benches and an engineers vice. I have just acquired a third lathe, a Myford ML7 which I am at present evaluating so I can decide which of the Myford's I will keep.
I have only just bought the Chinese lathe and had it fitted with DRO's prior to delivery. And what a bonus they are! So good in fact that I decided to buy another set for the Milling machine. Whilst my engineering experience can only be described as limited, I find the use of DRO's has affected my accuracy levels which have improved tremendously (although that's not saying much!) and would recommend their fitting to any model engineer.
Prior to retirement I built for my son's 17th birthday a Locost car. This
was a tremendous project and a great feeling when it passed its test. The book it was based on suggests it can be built for £250. Ours was nothing special in the sense of all new parts but still cost about £900 to build!
