Author Topic: Potty Simpson build - MZT  (Read 10787 times)

Offline mzt

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Potty Simpson build - MZT
« on: July 23, 2012, 02:26:08 PM »
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
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Potty Simpson build - MZT
« Reply #1 on: July 23, 2012, 02:26:43 PM »
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
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Potty Simpson build - MZT
« Reply #2 on: July 23, 2012, 02:43:32 PM »
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
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Potty Simpson build - MZT
« Reply #3 on: July 23, 2012, 02:44:25 PM »
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
This is a fitting job,
not a production job that can be measured in.

Offline smfr

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Re: Potty Simpson build - MZT
« Reply #4 on: July 23, 2012, 04:35:02 PM »
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

Bogstandard

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Re: Potty Simpson build - MZT
« Reply #5 on: July 23, 2012, 05:01:12 PM »
Marcello,

Even though you are making it from some unknownium, you should really class anything like this as barstock.

That sure is some lump you've started off with there, and that is one of our secrets. We can see what we want in that big lump or twisted bit of metal.

John


Offline mzt

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Re: Potty Simpson build - MZT
« Reply #6 on: July 25, 2012, 11:26:16 AM »
Proper tools make a difference
And what a difference they make!

I had started the previous cut using the 24tpi frame: all the teeth were still there, but they had already faced hours of activities.
Not being entirely convinced I?d have brought the job to completion, there was no point into wasting shop time looking for a new blade, nor I wanted to risk one of the precious coarse ones.

By the time I got ?convinced?, I had already grooved the four faces: no place to start a new cut,
had to go on with what I had used before. You don?t want use a new blade into an old cut, You know.

On this occasion, I decided to risk using the 18tpi frame*, knowing it had only faced little use on aluminium.
Even took the risk of cutting closer to the scribed line: You really need to make it all wrong to get a wandering cut into C.I.




Putting the ?difference? into numbers, this job was done in 22 minutes.

Marcello

(*) Yep! Some years ago I bought myself three identical frames, to put an end to the repeated blade changes, to suit the job at hand.
I wish I had purchased quality ones. 
This is a fitting job,
not a production job that can be measured in.

Offline mzt

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Re: Potty Simpson build - MZT
« Reply #7 on: July 25, 2012, 11:53:50 AM »
Simon,

I don't think I will get it anywhere close to a "diamond" however high the carbon contents in it,  :shrug:
Neither sure it will be a runner, and that would be prize enough for me.
Plenty of room for screwups on that cylinder, yet: I really wish I had already cut the next step or two.
Will do, in due time: I really need to tackle them with no distractions, and a couple of engines close to the "final test" are no help.

Marcello
This is a fitting job,
not a production job that can be measured in.

Offline swilliams

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Re: Potty Simpson build - MZT
« Reply #8 on: July 25, 2012, 12:09:00 PM »
Looks like you're doing a fine job there Marcello. The best way to get a runner is to have a go just like you're doing, you'll get there


Cheers
Steve