Skipjack by michael mott - 1/8th scale - SMALL - 19 foot open launch

[Omega1234]

Mistakes, or not...still absolutely amazing that you're building your own motor!!!!

[captainbob]

Three part before it’s right? I’d hate to tell you how many parts I threw away.  But, Michael, it’s not how many parts you make but the way you make them.  It is the rounding of the top surface on the head instead of leaving the edges sharp and looking at the mounting holes on that last block and the way you shape around them.  Many would have cut straight across like the edge touching the paper.  It is that sort of shaping and detailing that make you a master modeler in metal and in wood.

 

Bob

[michael mott]

 

TAKE... ME... TO... YOUR... LEADER

 

Sorry I couldn't resist, I just showed this to Jude and she said hey it looks like a face then in a robotic voice said "take me to your leader" I laughed out loud.

 

Just a bit more fetling and then I can move on to the next piece. I need to add a couple of relive grooves so that the jacket clears the valve springs, I will use an .093" end mill. lay the block on the top face and centre the end mill over the valve guide holes and just take a whisker off down to the holes.

 

Bob thanks for your very kind comment.

 

Thanks also for all the likes.

 

Michael

[Twister]

TAKE... ME... TO.... YOUR... LEADER...

 

That gave me a chuckle - your wife is quite correct although for me my instant reaction was that you were creating the 'Cybermen' from Doctor Who!

 

Fabulous work,

 

Regards,

 

Row

[mtaylor]

Impeccable machining, Michael.  I'm always amazed at what you do in miniature.  

[druxey]

What more to say? It's already been said, Michael!

[realworkingsailor]

I need to stop by here more often... Yikes... That's some scary impressive machining. Can't wait to hear it turn over for the first time! (When you get that far, of course)

 

Andy

[michael mott]

Thanks for all the likes, and to Row ,Mark, Druxey, and Andy thank you for your kind remarks they are very encouraging.

 

Began working on the new head part today but first I needed to make a couple of tools to help with some of the tasks.

 

first one was an end mill that was .155 in diameter and with a .015 radius at the cutting edge this was to ensure that the combustion cavity had a bit of a cove rather than a sharp corner.

 

 

a test cut

 

 

 

The second one was to make a collar for the 6 x .05mm tap so that I could tap in line accurately without taking the drill chuck out. It is just a disk of 1/2 inch aluminum with a couple of grub screws at right angles I ground a couple of 1/16th flats at the threaded end of the tap then I could use the drill chuck as the guide by releasing the tap from finger tight this way the drilled hole and the tapping are able to be accomplished without moving the work.

 

 

Then a lot of fiddly settings to shape the cavities.

 

 

 

 

 

 

next comes a lot of filing to finalize the shape.

 

Michael

[Jack12477]

Very Impressive machining Michael

[cog]

Lovely details, not to say sublime!!! (Starts to look like a BLMC Mini engine )

[hexnut]

 (Starts to look like a BLMC Mini engine )

About the right size, probably the brass one will have a bit more power and low-end torque... :P

[popeye the sailor]

I'm just sitting back.........just amazing metal work.    you know........with all the metal filings your kicking up,  have you given any though towards getting into smelting?

[michael mott]

Thanks everyone for stopping by and for all the likes, it is very motivating.

 

I have been out of the shop since Thursday evening I went to Calgary to visit my grandsons and play "electric trains"

 

Today I did a little more work on the water jacket, I finished shaping the insert for the bottom of the jacket sweated it in place and bored the holes for the sleeves.

 

Also did some shaping of the top part of the cylinders. after making a second milling cutter for the curves on the top.

 

 

 

 

 

 

 

The stainless sleeves are reamed and fitted, they are a press fit.

 

 

Michael

[Bedford]

Clearly you have some years of experience in machining Michael, so interesting to follow.

[cog]

Stunning Michael. You mentioned 'press fit' ... how much pressure do you use to push them in?

[michael mott]

Carl that is an interesting question? and I am unable to give you a definitive number, I used the milling machine vice to push them in and in order to ensure that they stay in I am adding a couple of flats on the outside of both so that they will lock against the surface of the crankcase. I will post a pic later which will make it more clear. as far as the diameters go it was a case of "go"  "no go" The no go was the diameter that was the push fit probably .00075" difference.

 

Steve, thanks yes I have been shaping metal for a long time. Got my "O" level metalwork two years early, thanks to a couple of very special teachers at my school. Our drafting teacher was from Napier Aero Engines. His Uncle was a model ship builder, And my woodwork teacher taught my own father. My metalwork teacher was very encouraging, and tough as nails, he did volunteer work at Wormwood Scrubbs (penitentiary)

 

Thanks to all who added likes.

 

Michael

[mrjimmy]

 

Hey, Michael.......

 

I have always been impressed with your ship building skills, but now I am overly impressed with your machining skills.  I can't decide which one is better.  It's kind of like which came first....... the chicken or the egg?  Well done; I am enjoying your log immensely.

 

Si

[popeye the sailor]

you wear the hat well Michael 

[michael mott]

Si, thanks for the kind words, Denis I like your new avatar, The song "Imagine" is my favourite song of the last century.

 

I started working on the crankcase it is cut from a block of brass that a friend gave me, it was given to him by somebody who melted down a bunch of odd bits of brass. it is hard and fine grained. The block was about 5 inches long and 3 wide and about 1 3/8 thick looked like it was cast in a mini bread pan. The brass cut nicely in the cut off saw.

 

 

This is the progress on the flats that will slot unto the crankcase hole. this will ensure that the sleeves remain seated, this is because I am not familiar with the differential expansion of the brass and stainless when the engine warms up. I doubt that there will be any problems so this is just to keep my mind at ease.

 

 

Michael

Edited November 19, 2014 by michael mott

[EdT]

Fascinating work, Micheal.  Will you be making piston rings?  Is it 4-cycle?  I can't wait to see the valve train.

 

Ed

[michael mott]

Good afternoon Ed, The idea of making the piston rings is appealing. There are a number of threads on the model engine site that have basic tutorials on making them. some folk seem to have no trouble and others find it difficult. Fine grained cast iron is the key from what I can gather and annealing the rings is the tricky bit. I shall have to look into the sources of the iron locally.

 

The engine is four cycle so the valve train will be an important element to get correct. I am going to use a Hall effect transistor ignition system.

 

Thank to all for the likes

 

Michael

[Bedford]

This is going to get quite intricate, at this size the cam and valve gear will be very small.

I don't want to miss any of it!

[michael mott]

Steve the valve stems are .046" it is the springs that I will be concentrating on first.

 

Michael

[michael mott]

After doing a few experiments with the valve stem springs and keeper, I have increased the diameter of the valve-stem to .060" inches leaving the narrow section for the keeper at .046"

 

This was one of the early tests using the .046 stem the spring is .078 in diameter and the wire is .011. the keeper was a bit fiddly. I can safely increase the stem diameter and still maintain the .078 diameter springs the length of the springs are ..259" presently I am learning how to wind them so that there is a double coil at each end with the wider spaced turns in between. I have found that it is better to make them this way rather than winding a length then stretching it out to form the compression spring.

 

 

The crank case is progressing well at this time also. there is a fair bit of hand filing to finish up the corners because I do not have the requisite end mills to do all this work on the milling machine.

 

 

this next picture shows the flats on the sides of the liners slipped through the top of the upper part of the crankcase.

 

 

that's it for now.

 

Michael

[Omega1234]

Hi Michael. Being a total ignoramus about these things, the sad thing is that I have absolutely no idea what you or anyone else has been talking about. Heck, I'm so gullible about engines that I even believe the car mechanic! On the otherhand, I do know excellent craftsmanship, err, mechanic'manship when I see it.

 

Damn good stuff!

[captainbob]

Springs are tricky, yours look great.

 

Bob

[michael mott]

Omega, here is a drawing showing the cross section of the engine and the camshaft with the valve in the open and closed positions.

 

valve train.pdf

 

Bob thanks for the compliment, one of the difficulties of working with the small sizes is that when drawing they are as big as the screen and it is a constant effort to remember the real size as I am drawing.  when an area looks about right and then I realize that the dimension might be only 1/64th I have to do some rethinking.

 

Michael 

[captainbob]

I know what you mean. One of the jobs I had was designing connecters.    A contact .25 long and .04 dia. looked huge, scaled up on the screen, until I would watch it being made.

 

Bob

[michael mott]

Thanks for all the likes and encouraging comments.

 

I had to make another cutter to make the recesses in the main flanges

 

 

I have already drilled the holes to accept the camshaft bearings they are larger because I need to be able to clear the raised cams.

 

 

An overall shot of the progress to date.

 

 

A close up of the new cutter, I needed a long reach with a small diameter cutting edge to fit next to the body of the case. it is hardened drill rod the diameter at the cutting face is .086" The bolt holes are .060 and the case it tapped ready for the 0x80 bolts.

 

 

Michael

[SJSoane]

 

Michael,

 

I am at a loss for words to describe how incredible this engine building is looking. Your metal skills are beyond my comprehension. It sounds like you had some great teachers, but I have no doubt you were an exceptional pupil!

 

Mark