Engines > From Plans
Potty Simpson build - MZT
mzt:
not sure the "barstock" label would fit on this build. Neither the "commercial or own castings" would, sure.
Will definitely put some barstock parts in it, not to see this thread being moved to a purposely created "scraps" board. ;)
Design and proper build thread as Stew posted them can be seen here: http://madmodder.net/index.php?topic=6485.0
Marcello
mzt:
The Cylinder Block
That?s the only piece I have in suitable sizes, I?m not even 100% sure there will be enough meat beyond the crust to get the job done.
What I will find inside of it, I plainly do not know.
First problem I had to face was about holding it into the vice: the jaws were not deep enough to hold it above its centreline, no parallel lines (let alone surfaces) to ease the job, and one only small almost flat area where it was sawn off from whatever it was attached
to.
Put it lenghtvise into the vice, enclosed between a couple of clamps used as additional jaws, then machined a starting flat on top of it, using the oldest, dullest, roughing mill I have, 20mm dia. IIRC.
Did not want to risk the precious carbide inserts of some other mill more suitable for the job.
The HSS mill didn?t last long, the glazed crust having quickly had reason of what was still in its cutting edges.
But the setup was firm, and that was what I wanted to know for sure. Time for a change.
Now on the opposite surface, as parallel to the first as I can get it. Parallelism is not an issue, at the moment:
I will choose later wih one of the two will be used as reference surface to machine the others.
Made my choice. From now on, all machining will be done between fixed jaw and dovel, with parallels (if HSS blanks can be so called) on the final cuts.
No climb cuts were taken while using that 2 inserts 30mm mill, unused axis locked, max depth I could gain was 1.1mm
(above that, the quill raised by itself during the cut, however tight I locked it), speed around 1300rpm, cuts maximum 12mm wide (if not for some operator?s errors),
feed.. eh.., feed was just cranking like hell: the faster the better (the less the machine was complaining, the better the finish).
Several hours of that, rather tiresome in the end.
I wished I had a suitable arbour to put this 63mm monster to the test.
End of the day, if not of the job: the piece is to size within the limits of my measuring tools, a few voids are starting to show - that?s not good news, we?ll see.. ?
As for what I?m planning for next, recent experiences taught me to begin with drilling a hole somewhere in the material I?m gonna discard and test-thread it:
don?t want to risk ending with a finished cylinder I cannot tap (though I would probably find press- fit or loctite the studs, if that were the case).
The eventual behaviour of my boring head on C.I. in general, if not on that workpiece in particular, is a mystery, too.
We?ll see.
Marcello
mzt:
Yesterday night I had a little shop time I wanted use for a quick drilling and tap-testing of a hole somewhere into that block.
On second thought, I decided to take the longer, but safer, way of scribing FIRST and drilling NEXT. I seem to recall that random
placed holes have the bad habit of getting in the way on later stages of the build.
Being in haste, I hurried with rulers, squares and dividers for a while: had a glance at the finished mess and went looking for
solvent and rag. Either I do it or do it not, doing it bad makes no sense.
Decide to treat the thing as it were a casting (well, it IS a casting! Is it not?) and clamped it to an angle plate to set it vertical
with all the faces square to the reference plate. Then brought into play my digital scriber and presto, got it done as precisely as I needed it.
It took less than on the previous attempt, but I will never learn that.
Here it is, scribed in one piece together with the base (for the moment, will decide what in due time). The blackened parts needing a complete
removal however I will tackle the job, the encircled area showing the largest void I can see at the moment.
No time for a second check of the dimensions, to say nothing about drilling. Maybe tonight.
Marcello
mzt:
Got curious about using an hacksaw.
Started with a groove about 1mm deep, little more than 1mm outside the end line, turned the piece into the vice 90deg,
grooved again and so on till I made all four. Then, I deepened each of them to about half of the blade height,
and finally the two on the 35mm faces down to full blade.
Made the cut on both the large sides, reversing the wp. into the vice two or three times. Wasn?t sure about the pros and
cons of mixing cast iron dust with the thick oil I had at hand, so I made it dry. It took less than an hour of hand powered
machining, slow motion, caring to make use of the full blade length. Job ended before I was sweating.
The cut was straight, close to perfection, and the ?opening? of the wp. revealed to me some nice fine grained cast iron.
Made my day!
The offcut went back to the metals shelf, You bet it.
Marcello
smfr:
Wow, that is quite the lump of metal. You should save one of the ends to display next to the finished engine ("a diamond in the rough" and all that) :D
Simon
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