another Snow engine

[Roger B]

Bad time, but no real damage just frustration 

As I was discussing with Stan Shire mistakes are almost always big, its not 0.01 mm too small its 10mm (or 1") too short.

[gbritnell]

Hi Achim,
When I made the drawings for my current project, the flathead V-8 engine, I had the block drawn so when doing the oil pan I took the bottom view of the engine and used that as the starting template for the oil pan. I finished drawing the oil pan and everything looked fine. I had to buy a large rectangular piece of aluminum for the pan, around $24.00 plus shipping as I recall. I started the machining by progressively drilling larger hole to remove the heavy stock. I then started cutting away with ball nosed mills to hollow out the cavity. At this point I had about 8 hours of machining. It wasn't until I started cutting the cavity for the oil pump that things just didn't look right. I double checked the drawing and said "it matches the drawing" so I kept machining. I was now up to about 12 hours. The more I looked at it the more something just didn't seem right so I stopped. I went back to my Autocad drawing of the oil pan just to check. It still seemed ok. I then opened the drawing for the bottom of the block and as soon as I did I realize the mistake. I used the pan rail of the block as the template but never inverted it to it's true position. (symmetrical opposite) Now I had an expensive piece of aluminum that I couldn't use for anything else, a whole floor full of chips and curls, and a lot of wasted hours. Back in my formative years I would have taken a hammer to something to vent my frustration but over the years I learned that it never accomplished anything so I threw the now worthless chunk of aluminum in the scrap box, ordered another one and started over.
I feel your pain but it's part of machining.  I defy anyone to say that they've never made a mistake machining! Some are small and then others are large, and sometimes expensive.
gbritnell

[fumopuc]

Simon, Dave, Bill, Don, Kim, Roger and George first of all, thanks for your always encouraging comments. I have had been sure, that I am not alone with some mishaps, but now I got the confirmation about that. Anyway my story is a small thing, if I read what George has done with his twice made oil pan. George, thanks for telling the whole story.


In the meantime the yellow truck of DHL was her last week and the cross head is nearly finished.
First picture showing right side  the bad one and left side  the new good one up to the same state.
Now the 18,5 mm long cylindrical bore for the later made bronze bush could be clearly recognized.


Next to do is the disassembly of everything and a final machining at all cylinder heads must be made, there is some overstock in the width.
This must be shorten in accordance with my European metric lip seals I will use and the later pressed in bronze bush.




PS: Kim, there was a pure friendly and positive discussion with the guy at the lathe.

[Dave Otto]

Great progress Achim!

The second cross head turned out very nice; its all starting to come together and looking great.

Dave

[fumopuc]

Hi Dave, thanks for checking in.


The aluminium cylinder parts are still at the anodising company, so it was time to make the pistons and piston rods.
My purchased piston rings are 27 mm, so all  is very close to the original design of Doug Kelley.
I have made the pistons 0,05 mm smaller than the dimension of the liner.
The piston rods in the chuck always protected by some can aluminium sheet.
A sample assembly was fine, so I have made finally the rod coupling and the movement can be seen in the 20 sec video.
Waiting for my cylinder parts now.
<a href="https://www.youtube.com/watch?v=3REVuJN7zJI" target="_blank">http://www.youtube.com/watch?v=3REVuJN7zJI</a>

[Don1966]

Awesome Achim. Your getting closer and I.......Like................... 


 

Don

[Kim]

It looks beautiful, as always Achim! Excellent work.

The movement seems really tight.  Is it supposed to be that tight?  I know nothing about this, I'm just trying to follow along and understand.  Just seems like a lot of friction there.  But maybe that's what you have to have for it to work properly?

Kim

[fumopuc]

...
The movement seems really tight.  Is it supposed to be that tight?  I know nothing about this, I'm just trying to follow along and understand.  Just seems like a lot of friction there.  But maybe that's what you have to have for it to work properly?

Kim

Thanks  Kim. At the moment I am quite happy with the friction. There are 4 brand new piston rings running in these two liners and a bit friction must be there. I still have the little electric motor, connected with the crankshaft by a belt and pulley. After a further assembly some " running in program" is scheduled.

[Kim]

OK thanks. I've never done an IC before, and definitely never used CI rings.
Thanks for the explanation,
Kim

[b.lindsey]

More nice progress Achim. Where will you be getting your seals from?

Bill

[fumopuc]

Hi Bill, thanks for watching.
My piston rods are made from 8 mm grinded (ground ?) silver steel. It was a bit difficult to find the right lip seal from FKM (FPM) for it, NBR was easy, but not a good choise. Finally it was found in the Seat/Volkswagen spare parts cataloge. A lip seal from FKM (Viton) 8x14x4mm made by company Elring in Germany. This dimenson is very close to the design of Doug.

[Ian S C]

Ground Silver Steel.
Ian S C

[fumopuc]

Ground Silver Steel.
Ian S C

Thanks Ian, I am struggling sometimes.

[fumopuc]

Some good and some bad news.
On Friday morning I have picked up my black anodised cylinder parts.
Next to do was to make the bronze bushes for the piston rods and to get them into the cylinder heads.
My plan is to heat the aluminium part in the toaster oven to nearly 200°C and to knock the bush in, using a simple arbor and a hammer.
The extension of the hole in the cylinder should be nearly 0,057 mm in diameter at 200°C in theory.
So my first bronze bush was made 0,05 mm bigger in diameter than the hole in my uncoated sample/set up part.
The cylinder head was heated in the oven to 220°C, I have put it on the bench, I took the bush with the arbor, some oil on the bush, some knocking with the hammer and "et viola" job was done.
A sample assembly at the engine with the piston rod was fine.
So I have I started the next one, the first one with black coating at it, my first real cylinder head.
During hammering the second bush into the real black part there was some locking already and I had to increase the force with the hammer already.
A sample assembly with the piston rod at the cylinder has shown the first mess.
The bush is not 100% straight in its bore and during the tightening of the bolts the piston rod will be clamped.
It is only, may be 1° out, but it is enough in this configuration between working and looking.
It took me some time to recognize, but at the end this is the failure.
Because I have been a lazy boy, I have tried to give it another push, cold with a bigger hammer and a more solid underground, an this was the next failure.
Now, the part is slightly bend and I would say this part is nearly dead.
The right option should be to put it on the lathe, remove the oblique set bush, polish or increase the bore, make a new bush and try it again.
This is what I will try first now, to learn and train the rescue of such a part.
May be there is a chance to do an entire rescue, I will report later.
Also a simple fixture will be made to get a better alignment for the first set of the bush over the cylinder head and I will increase the chamfers at the bush and the cylinder head.
A reduction of overlap to 0,03 mm is also in my mind and the bushes will get a 5 or 6 hours stay the deep freezer.

[Kim]

Achim,
So sorry to hear about your troubles getting the bush set properly.    That's got to hurt.  I'll be pulling for you and hope you can salvage the part!  They all look so beautiful!

Kim