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

[WackoWolf]

Beautiful metal work. Keep the updates and pictures coming. A pictures says it all. Thanks

[EdT]

Looking wonderful, Micheal.  Really superb work.

 

Ed

[Jack12477]

Mike, I have to echo the sentiments of all the others. Truely impressive machining.

[Sven]

I'm speechless. This is amazing!

 

It looks like half of the engine of my 1929 Austin Seven!

[druxey]

Beautifully executed, Michael. Your metalworking skills are truly impressive.

[michael mott]

Thank you all for the very encouraging comments they are really appreciated., I have been doing a lot of calculating this morning because it looks like the gears for the timing are 64 teeth and 32 teeth respectively. I do not have dividing plates for my rotary table and so it makes sense to use divisions of 360 for making the gears. all the standard gears that are in the ball park for the diameters that I am locked into are not the correct ratio of 2:1. 64DP comes the closest,.

 

I have decided to bite the bullet and make them to a DP of 75 which gives me 60 teeth and 30 teeth for the diameters that I need so now I also need to make the gear cutters for both sizes which means a number 3 cutter and a number 2 cutter. My 48 DP cutters which I made a few years ago are just too big.

 

There is a great article in the Model Engineer October 1 1971 issue by D J Unwin on how to make gear cutters with all the formulas for making them. 

each cutter require a separate tool to make the cutter, They are simple tools but it is an extra step in the chain.

 

Thanks also for all the likes 

[michael mott]

Set up the table of offsets to machine the curved inner surface of the oil pan, and after two hours of cranking the block back and forth the shape slowly emerged. I lowered the cutter .010" for each pass.  Next I will cut away the negative areas where the cranks will rotate and either side of the bottom of the crankcase then flip it over to finish off the bearing recesses. then a brass shell will get soldered onto the cross members, creating the hollow shape.

 

 

I made it this way because I was stumped as to how to get the inside shapes of the oil pan, I suppose I could have set up a boring bar and scooped out the recesses the only issue with doing it that way was being able to have an opening underneath the central bearing beam to allow the oil to move about in the bottom and equalize rather than being isolated to each recess. the other advantage to making it this way is is that I will be confident that the wall thickness will be consistent.

 

Thanks for the likes.

 

Michael

 

 

[EdT]

A complex bit of work.  I'm still not sure I understand this last piece, but will patiently await the next steps.  Amazing.

 

Ed

[mtaylor]

Now that's incredible.. machining the oil pan.  Anyone else would have bent and silver-soldered some brass.  Michael, your machining skills just amaze me.

[michael mott]

Ed hopefully the next set of pictures will clarify my description. Mark well it is not a complete machine job there is some soldering however I did not want to anneal the brass that has the bearings braces so opted for soft solder which will be more than adequate for the oil pan.

 

The first picture shows the material being removes that will become the hollow areas'some parts were machined by the numbers and the bulk was just milled away by eyeballing it.

 

 

Next the 1/32 thick sheet was annealed and curved over a steel bar.

 

 

It took a while to get it fitted cleanly, the flat area on the middle bearing wall is to allow the oil to pass through to equalize both chambers.

 

 

The next picture shows the assembled parts cleaned up a bit getting ready to do the soldering.

 

 

Resting the upper part of the crankcase to see the overall scope of the whole engine.

 

 

In the next picture you can see the central cross member.

 

 

 

There is still a fair bit of cleaning up to do but I am generally pleased with the progress.

 

Again thanks to all who have looked in and pressed the like button.

 

Michael

 

 

[Bedford]

Clever design Michael, as one would expect.

Why the extra sump area outside the crank case?

[michael mott]

Hi Steve

the extra length serves as a housing for the reversing clutch for the prop. like this one on the old marine site

 

 

 

Thanks for all the likes

 

Michael

[Twister]

Michael,

 

As always, incredible workmanship.  For me the idea of machining something at such a small scale would be a non-starter! At least if one were to make a mistake the material costs would be negligible - thank goodness we never think of our own time!

 

Regards,

 

Row

[popeye the sailor]

very interesting process so far Michael.   having worked around cars and engines most of my life.......it's really something to see one being made from scratch     super job so far!

[Bedford]

Ah yes! that makes sense.

 

Are you going to do the whole reversing mechanism?

[michael mott]

Thanks to all the builders who pushed the like button.

 

Denis, I am learning a lot about engines myself at the moment.

 

Steve yes I am going to make the reverse mechanism as well.

 

Today this morning I was drawing up the feed-water pump, I ended up finding a good internal design in one of my old Model Engineer mags page 1265 October 1981 for a 3 1`/2 inch gauge Stanier 8F. I will need to make it smaller but the design will fit into the pipes that are on the prototype buffalo which pumps off the camshaft like this one on the Old Marine engine site

 

I worked on the pan today and roughed out the half round bottoms for the crankshaft and drilled and tapped all the 0x80 holes for the studs.

 

 

I looked at all my stashes of steel wire and rods looking for some .060 to make the steel 0x80 studs from. I could not find any that was exactly .060"

I then came across a most unlikely source, the re-bar ties left over from building the house just happened to be .060 the stuff threaded up a treat. had to make a small open ended wrench to get to the valve side because of the overhang.

 

 

Did a test fit of the crankcase and pan and water-jacket, it all slipped together nicely. It has really helped with the accuracy of cutting and drilling to set up the dial calipers on the mill, and working from  a 0 centre 

 

Michael

 

 

 

[Bedford]

I've been doing some machining today too but NOTHING compared to what you are doing !!

[michael mott]

Thanks for all the likes today.

 

I reached a milestone today and got the main bearings roughed in.

 

First I machined up the keeper blocks. and some studs.

 

 

 

Assembled them in order to ream them for the 1/8th shaft.

 

 

I thought it best to use the hand reamer rather than setting it up in the mill for the machine reamer.

 

 

After thinning down the area on the upper crankcase it all went together quite nicely. and the shaft rotates easily.

 

 

I am still deciding whether to fabricate the crankshaft or machine it from solid bar, either way it will be tricky.

 

Michael

 

 

[mtaylor]

Michael,

 

From my hot rodding days, it might... maybe... hope... be easier to fabricate it.  As I recall, on the machined ones the billet had to be ground on a special crankshaft lathe.  No matter what you decide, I can't wait to see what you do and how you do it.  This is some beautiful mill work.

[SJSoane]

Michael, we are all spellbound. This hardly seems possible by human hands and tools at this scale.

[WackoWolf]

Excellent machine work. Love it. Keep the updates and pictures coming, I now we are all watching. Thank you for sharing this.

[Twister]

Superlative machining Michael, but then we wouldn't expect anything less!!

 

To machine or fabricate the crank shaft? I've never attempted either (and am a very long way from trying!) but I would have thought that at the scale your working at fabricating would probably be quicker - from what I've seen of the processes the machining option looks to be long and tedious without cnc lathe control.

Decisions, decisions... I'm sure whichever option you go for the results will be phenomenal. It's at times like this that I wish a university engineering degree actually furnished me with practical, proper engineering skills instead of lots of theory, the majority of which has been long forgotten...

 

Looking forward to seeing which way you decide to go with this,

 

Regards,

 

Row

[EdT]

I continue to be enthralled, Micheal.  I had almost forgotten the size of this until you mentioned the 1/8 shaft.  Will you need oil seals?

 

Ed

[captainbob]

Machining like that is something I only dream about.

 

Bob

[druxey]

Beautifully executed so far, Michael. Left-over rebar ties? Never throw any stuff out, "It might come in useful..."

[Mark Pearse]

lovely work Michael, it's a pleasure to watch;

 

will you have to adjust the compression ratio for scale?

 

MP

[michael mott]

"From my hot rodding days, it might... maybe... hope... be easier to fabricate it."

 

Mark this is the option that I have decided upon, When I have more experience I would like to have a go at machining one from solid.

 

"we are all spellbound. This hardly seems possible by human hands and tools at this scale"

 

Mark As I am working I often muse to myself how would a watchmaker tackle this fabrication, and then look at some of the amazing work they do and am humbled by their skill.

 

Joe, and all Thank you for following along and your kind comments.

 

"but I would have thought that at the scale your working at fabricating would probably be quicker - from what I've seen of the processes the machining option looks to be long and tedious without cnc lathe control."

 

Row, I have read a couple of tutorials on the model engine forum about machining the crankshaft and there is a fair bit of preparatory jig making to set up for the offsets and keeping it all inline, You are correct in suggesting that fabrication is faster, not that speed is a concern.

 

"I had almost forgotten the size of this until you mentioned the 1/8 shaft."

 

Ed, this is something that continually trips me when working on the drawings because it all looks so large on the screen

 

"Machining like that is something I only dream about"

Bob, funny you should mention this, because I have been waking up with immediate thoughts about how to do the next task, sort of solving it in my sleep.

 

"Never throw any stuff out, "It might come in useful...""

 

Druxey the only concern with having this mindset is one almost needs a warehouse to store all this stuff I have to argue with myself all the time "really do you need to keep this?"..... Yes because I might need it one day!"

 

"will you have to adjust the compression ratio for scale?"

 

Mark, I honestly have no Idea, I am basically flying by the seat of my pants on this one. I suppose that the only way I will know is when I give it a spin and she fires up. I would be able to make some adjustment with the length of the valve caps in the top of the cylinder head.

 

Thanks to all those who added a like the previous posts.

 

Suppers ready so I will add some pics of the crankshaft after supper.

 

Michael

 

[michael mott]

This afternoon after getting the shop warmed up a bit from 3 degrees to 13 degrees C I worked on the parts for the crankshaft.

 

First I thinned down a piece of 1/8th gauge-plate to .094 then drilled and reamed 8 holes to 1/8th diameter.

 

 

Next I cut the piece into the four plates for the sides of the con rod bearings part of the crankshaft, I used a new blade in the jewelers saw.

 

 

A 1/8th set of dowels were slipped through the holes and the group were clamped in the vice and filed to shape.

 

 

Then polished up with 400, 600, and 1200 wet and dry sandpaper., I like it when I can get a reflective surface, then I know it is pretty smooth.

 

 

 

The sides of the plates will get polished Tuesday or Wednesday. Tomorrow is errand day in the big city.

 

I turned up the .344" long 1/8 inch diameter shafts for the big ends of the con rods and did a dry assemble to see how the whole lot looks.

 

 

 

I will silver solder the lot together then cut off the parts of the main shaft that are not needed. "The proof will be in the pudding" as they say, so crossing my fingers for a clean soldering job.

 

Michael

 

 

 

 

[Bedford]

Michael, you will have heard the expression "to sleep on it" it works and a good sleep has helped solve some of the trickier issues with my schooner.

 

A note on polishing the internal metalwork, I'm reminded of the story of a car maker in the UK that prides itself on quality, they needed to start making auto gearboxes and bought one with a good reputation and reverse engineered it but being the fastidious types they are they machined the entire inside of the cast housing which the original maker omitted doing. Gearbox after gearbox failed until they sought the help of the original manufacturer who told them simply, "don't machine the inside of the case. The rough casting stops oil running quickly down and causes it to drip onto the mechanisms which helps lubricate it all".

 

Now the truth of this story, I can't be sure of, but I would imagine you might be better off not polishing surfaces that don't need to be.

[cog]

Michael,

 

How much problems will ballancing the crankshaft give you. Like this I would expect a lot of vibrations on it