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

[michael mott]

Druxey thanks I did search in a couple of my dictionaries and the two word seem to come closest with the definition of a small key or small wrench for tuning stringed instruments as in the harp or piano by turning the pins to which the strings are fastened.

 

The definition of wrist pin is a pin joining the end of a connecting rod to a piston

 

Cheers Michael

[michael mott]

This was the sequence for the top end shaping.

 

the first shots showing the rotational shaping in the lathe using the chuck as a vice while moving the cutter back and forth.

 

 

 

 

 

Next using a rat tail file to finish off the shape

 

 

after filing but before final clean up.

 

 

ready to assemble

 

 

Michael

[NMBROOK]

I have had a wonderful time reading through your log Michael Your engine build is a wonderful piece of model engineering and totaling enthralling to read about it's construction.I wish I could revisit my college days with the plethora of machine tools available,knowing what I know now,I would have built a steam engine as my course project   .

I look forward following it to it's completion and imagine you will be doing a vid of it's first test run

 

Happy New Year

 

Nigel

Edited December 31, 2014 by NMBROOK

[druxey]

Bravo! That rod looks great. Thanks for clarifying wrist/wrest.

[mtaylor]

Now aren't you glad you're not doing an Allison V-12, Michael?     That is some beyond wonderful metal work.  And, doing the wrist pin end that way might have uses for other things... I'm filing it away.

[Bedford]

I'm with Mark, lots of learning and ideas here!

[michael mott]

Nigel thanks for your kind comments I am happy that you are enjoying the journey.

 

Druxey, thanks.

 

 

Now aren't you glad you're not doing an Allison V-12, Michael?

Mark, in a word Yes. I'm pleased you have found some of these processes useful.

 

I'm with Mark, lots of learning and ideas here!

 

Steve and Mark, that make at least three of us

 

Thanks for all the likes

 

Pressing on with the con rods today the first task was to split and solder the brass for the big end bushing, I decided to make these individually so that I could check that it was going to work.

slitting the rod

 

 

soldered ready for machining

 

 

turning down to the flange diameter

 

 

The final bore was done with a 1/8th end mill after first using a centre drill then a 3/64th drill.

 

 

Turning the central part was very tedious with very light cuts and double checking the diameter after each pass of the tool.The bush was then parted off. 

Tthe bore is .125" and the body diameter is .156" so the thickness of the bearing wall is only .0155" and that made me very cautious.

 

 

I used a soldering iron and a pair of tweezers inside the bore to unsolder the bushing, it popped apart very cleanly.

 

 

I turned and hardened a new button for the bottom of the big end of the con rod.

 

 

when everything was cleaned up the moment of truth,...... it fit Yea...a little stiff but not much

 

 

Then I wanted to check the height inside the cylinder and was very pleased with the outcome, I did notice that I plopped the top part of the crankcase on backwards after uploading the photographs... excitement I guess.

 

 

Now I have to repeat the process all over again tomorrow and I also have to relieve the bottoms of the cylinder liners to clear the con rods. I had drawn this in the details but have not done it yet, once that is done tomorrow the the piston with be able to move up and down in a complete cycle

 

 

Michael

 

 

 

 

Edited January 2, 2015 by michael mott

[jud]

Nice work. Like the way you made your lathe work as a shaper, well worth placing in the memory banks, sometime a mill is not the proper tool. Enjoying as well as learn from your machine work.

jud

[cog]

Michale,

First of all: A healthyh and prosperous New Year.

Superb job on the crankshaft bearings. I remember them from switching crankshaft on my 1972 Mini. I missed you making shell bearings for where the crankshafts is hold to the casing, or did you not?

[SJSoane]

 

Michael,

 

That looks like a full size lathe, making such small parts. I am impressed!

 

When you use a slitting saw in the lathe, which had never occurred to me as a technique--thanks for the insight!--do you shim up the stock to the center line, or it doesn't matter?

 

Best wishes,

 

Mark

[Chasseur]

Nice! 

 

Jeff

[Omega1234]

Hi Michael..the last photo of the engine in Post 309 has left me speechless. Utterly amazing work!

 

All the best for 2015

 

Patrick

[michael mott]

Jud, Carl Mark, Jeff thanks for stopping by and your kind comments.

 

I missed you making shell bearings for where the crankshafts is hold to the casing, or did you not?

Carl I did not make shell bearings for the crankcase (yet) I thought that since the main body of the lower crank case was already brass that i would not bother, I do not think that the engine will get enough run time to cause any problems, I could be way out in my thinking it this case but we shall see. the con rod is however aluminum so I put them in.

 

 

do you shim up the stock to the center line, or it doesn't matter?

Mark the answer is yes and no, the reason being that it depends on what I am cutting. Sometimes i would like to be able to cut just along the one edge of something as in a split collar for gripping a part to turn it.  I generally adjust the height with the tool post to get it to centre, This is one of the great things about quick change tool posts.

 

I have also been making more use of the end hand wheel on the lead screw rather than using the big handle on the carriage, which engages into the rack for moving the carriage when the lead screw is not turning. Originally I only used the lead screw when I was either cutting a thread or making long fine cuts using the power feed. I have been using it more these days because the hand wheel on the end of the lead screw is marked in .001" increments so it allows for more accurate positioning of the carriage, and seem to smooth out the motion of the carriage.

 

This is important when making precise cuts a specific length. The other is getting the cutting tool square and knowing the exact width of the tool, and getting the cutting edge on centre. I also listen to the cut a lot, it always amazes me how much we use our ears when using tools.

 

Thanks to all for the likes

 

Patrick thanks we must have crossed paths in the electronic world.

 

Michael

Edited January 2, 2015 by michael mott

[hexnut]

This is, literally, a privilege to watch.

When you de-soldered the bearings, did you leave some tinning on the surface for babbiting effect, or are you going w/ straight brass?

[pete48]

Incredibly amazing Work Michael, 

 

Best Regards,

Pete

[michael mott]

 

This is, literally, a privilege to watch.

Bob the privilege is mine having the luxury of good health,  time and materials to be able to follow my hobby. There are those much less fortunate because of many factors beyond their control, where life and the environment  intervenes.

 

are you going w/ straight brass?

 

Bob,Yes I will be going with straight brass for this engine. There was very little solder left, it was only the small sections of the wall on either side, the soldering iron was clean and held on the end of the composite until the heat melted that connection then the small bit of spring that was in the tweezers was enough to pop them apart.

 

I did not take a picture when doing the first one I will for the second.

 

Thanks Pete.

 

And to all who added likes.

 

Michael

[michael mott]

Today I finished the bushings for the con rods

 

The first picture is showing the soldered rod ready to be machined

 

 

the next is showing the bushing ready to be de-soldered.

 

 

ready to be installed in the big end of the rod.

 

 

filing to shape with the hardened button

 

 

ready to be assembled

 

 

test fitting

 

 

 

 

and finally here is a video of the engine to date.

 

That is a big milestone out of the way now I can move on to the camshaft and valves.

 

michael

[mtaylor]

That is a big milestone, Michael.   I'm getting curious to see how you'll do the camshaft.  I've seen them do it for the full size engines with a pretty much specialized bit of equipment.  I got a feeling we're about learn another trick or two.

[Bedford]

Congrats Michael. It looks really great in action.

 

Like Mark I think know there are some more good lessons coming up.

[Mirabell61]

beautiful machining Work Michael,

 

those Videos are great, ans also that reversing gear works fantastic, well done!

 

Nils

[EdT]

Congratulations on the dry test.  Fantastic work.

 

Ed

[SJSoane]

 

Michael, astonishing. I would not have believed it possible, and yet we saw it step by step. You are an inspiration!

 

You mentioned hard buttons several times for guiding your filing. How do you make those?

 

Best wishes,

 

Mark

[druxey]

Impressive, Michael, very impressive!

[Sven]

That looks just wonderful Michael. Those big end shells are unbelievable!

Will The valve stems be lubricated or will splashing get to them?

 

Matt

[captainbob]

And I see the reversing gear is working also.  Well done.

 

Bob

[Jack12477]

Nicely done, Michael. Very impressive!  Nice informative video as well.

[Twister]

I'm well aware that it's been said before in various guises but it really is the only appropriate comment I can currently think of:

 

So Michael, Thankyou so much for this incredible ongoing masterclass, you really are 'The Master'. I can say with all honesty that I really don't think I've ever learnt so much in such a relatively short period of time. Just love those big end shell bearing/bushings.

 

I'll finish with a question if I may, do you intend to fit similar shell bearing/bushes to to the crank main journals?

 

Regards & all good wishes for 2015,

 

Row

Edited January 3, 2015 by Twister

[popeye the sailor]

super video Michael........impressive!

[Remcohe]

My hat is off to you Sir, splendid work.

 

Remco

[michael mott]

MarkT, Steve, Nils, Ed, Mark, Druxey, Matt, Bob, Jack, Row , Denis, and Remco. thanks for your kind remarks

 

I'm getting curious to see how you'll do the camshaft.

 

Mark I thought I was on track to make these in pairs  112 degrees rotated from each other. First turning up a trial piece to   the major diameter of the lobes, then using the taper pins I fitted the piece to some 1/8th diameter drill rod rough filed them at 90 degrees like this. My thinking was that I could then use the rotary table and the mill to finish each lobe by following a table of offsets and rotating the piece.

I drew the rotary table to how the process would work.

 

 

 

camshaft template.pdf

 

The part was then set up in the mill

 

 

The first lobe worked well and after removing the pin and flipping it over end for end I was ready to cut the second lobe.

After making the initial cuts to remove the bulk of the material for the second lobe i was getting ready to make the final circular cut around the back side of the lobe when I realized I had cut the wrong side of the rough block of material basically leaving both lobes in the same plane. In order to satisfy myself that this was actually the case I went to rotate the table to get a better look. the cutter was still rotating and I grabbed the wrong handle because I had not pulled it off which I normally do when working the rotary. I gave the lower handle a full turn and instantly uttered a censored word!

 

 

not only dit the cutter eat into the work bending the shaft but also snapped off a bit of the cutter.

 

 

the result

 

 

So now I need to rethink the whole operation.

 

Next I am going to make a long single lobe and then part off the individual cams and pin them separately, I can salvage the rest of the cutter it will need a bit of regrinding on the end but that is not much more trick that sharpening a drill bit.

 

A long winded answer to you question.

 

 

You mentioned hard buttons several times for guiding your filing. How do you make those?

 

Mark  the buttons are some drill rod turned to the diameter that I want the finished curve to be, the smaller diameter slides into the hole and the larger diameter pushes up to the material that will be shaped

 

Once the two diameters are made I part it off and then heat it to cherry red and quench in water the button is then to hard to be affected by the file.

 

Will The valve stems be lubricated or will splashing get to them?

 

Matt I think that the splashing will do the work.

 

do you intend to fit similar shell bearing/bushes to to the crank main journals?

 

Row, Hmm the pressure is on, the original notion was not to add them, But I am thinking it might be better to add some.

 

Off for a swim at the local pool to warm up and console myself it was chilly in the shop this morning -2 degrees Celcius, -30 outside  probably cooled my brain down and that is why I forgot to remove the mill handle.

 

Oh well these test are there for us to learn from, no point in getting too cranked about it.

 

Cheers Michael