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

[michael mott]

Remco, Steve, Joe, and Row thanks for your very kind remarks. Thanks to all who pressed the like button as well.

 

I finished up the clamp ring today and made the actuating lever to open and close the ring, it is quite tiny but was manageable. in order to get the widths that I wanted quickly I spun up a disc on the lathe, bored out the centre hole on the lathe then stood up the rod with the disc still attached in the vice on the mill and offset the other hole .156" then took it back to the lathe and parted it off then used the jewelers saw to cut out the crank.

 

 

Then cleaned it up with some files, then polished it up to a rouge finish and beveled the hub to create the cam.

 

 

Here it is set in position with the spring loaded bolt in the open position the width of the flanges at the bolt are .290"

 

 

And here with the lever in the closed position the width of the flange at the bolt is .250" locking the gearbox casing.

 

 

This is how it works

 

next the rear cam locking collar.

 

Michael

 

[Bedford]

This is a beautiful mechanism, simplicity and elegance. I get how all of it works except the "spline" made from the socket head screw, what's that about?

[michael mott]

Steve the spline is for actuating the clamp so that the prop shaft is fixed to the casing or free to revolve have a look at this page

the image shows the keys on the prop shaft because I cannot make these keys i used a slpine instead and with use the spine collar to clamp in the same way as the plates in the clutch.

 

Michael

[Bedford]

Right, it is a dog clutch. It all makes perfect sense now. 

 

Can you tell I love old mechanisms?

[EdT]

I can't add any knew words, Micheal, but the like button just seems completely inadequate.  Beatiful design.  Beautiful workmanship.  Can't wait to see it running.

 

Ed

[Jack12477]

I have to echo EdT's words.  Michael, superb !  And the video is very informative, thanks for including it.

[michael mott]

Ed, and Jack, thank you for your kind comments. and for all who added likes.

 

I had to make a new band clamp because the tabs were not wide enough to bolt it to the pan. the new one was machined from a solid ring and then a lot of fiddling and filing to get it to spring just right.

 

 

 

I also whipped up a flywheel because it is tough on my fingertips turning the 1/8th shaft all the time to test stuff.

 

 

 

Today I worked on the clutch, it was a bit of a design build affair following the general principles, the gearbox and clutch will be underneath the cover so only the top of the linkage and the lever will need to be as accurate as possible to keep the appearance of the engine looking as the full size engine.

 

I abandoned the cap screw hex and made a hex broach from a 3/16 allen key. first I heated it up and let it cool slowly to take the hardness out of it, then cut a taper on one end of the hex. Next I added the beveled slots to create the cutting faces. I ended up making a second one because I forgot to temper the first one after re hardening it, it cut the first hex through about a half inch length of brass stock, and then I tried a longer piece of brass and it shattered into three.

 

 

Pushing the second one with the vice rather than using the hammer which is how I managed to wreck the first one.

 

 

At the back end of the broach I reduced the diameter before it was hardened so that I could part off the disks one at a time, as the broach was forced through, each time the broach reached the end I put it back in the lathe parted off another disc

 

 

Next I turned a few discs of mild steel off a blank that had been pre drilled for the keeper rods. the steel discs are 5/8 diameter and .020 thick the brass plates are 5/16 diameter and .040 thick. the steel discs will be fixed to the gearbox and rotate about the hex the hex will be pinned to the prop shaft and the brass plated will spin with the hex

 

.

 

Here they are test fitted for size, the wide brass collar is also keyed to the prop shaft and will be the pushing element to squeeze the plates together.

 

 

Time for bed

 

Michael

 

 

[captainbob]

It's beginning to really look like an engine, Michael you're doing things I can only dream of. And it's beautiful.

 

Bob

[druxey]

Very, very nice, Michael. Great little video as well!

[Mirabell61]

Wow !

Michael I am highly impressed of your skills, your manyfold wisdom and knowledgement for both boatbuilding and combustion engine building. Somehow and with much regret I missed to look into this build log of yours, it is worth every post, most interesting and a delight to study. Do you have a machinery Workshop career ?

 

I presume that you will be operating this Buffalo 2Hp engine per RC control, with the Launch and can hardly wait to see it in action

 

Nils

[Twister]

Michael,

 

As has been said before, simply hitting the 'like' button just doesn't do justice to your phenomenal skills. But then neither do the words I can think of to pass on my admiration for your work so I'll keep it simple:

 

WOW!!

 

Once again, many congratulations for achieving what many of us would consider to be impossible.

 

Regards,

 

Row

[michael mott]

Bob, Druxey and Nils thank you all for your kind comments, they are very encouraging, makes all the re do's worth while.

And not forgetting all the people who added a like.

 

 

Do you have a machinery Workshop career

Nils, Not exactly, I have been making stuff though for a long time, and as a commercial model-builder and designer I had a lot of projects that gave me the opportunity to learn new skills. I have learned from my mistakes what works and what has not. I had good teachers at school, who encouraged a genuine curiosity for learning how to do things for myself.

My woodwork teacher taught me how to sharpen tools.

The first machine that I purchased was a Myford lathe back in 1971, I learn new things about how it works every day it seems.

 

Michael

[michael mott]

Row, thanks, we must have been posting at the same time, your comment is greatly appreciated. 

 

Michael

[dvm27]

So you do sleep! I was beginning to wonder. Your output, both quantity and quality, is inspiring.

[mtaylor]

I was wondering the same thing that Greg mentioned.  Your output and quality is amazing.   This goes way beyond a "like" button.  It's a masterpiece.

 

Edit.. I needed to find out what the broaching was about.. now I know:  http://en.wikipedia.org/wiki/Broaching_(metalworking)

 

Your builds are an education unto themselves.  Thanks for that also.

Edited December 18, 2014 by mtaylor

[cog]

I have to join in/agree with the two former posts. I'd like to add that it is fun to watch the progress and every time I'm looking forward to your next 'surprise posting'. It's wonderful to see it/them grow

[SJSoane]

 

Michael, this is becoming a master class in metal work. I don't even understand some of the things you are doing, but watching how you make the parts is fascinating.

 

Mark

[michael mott]

Greg, Mark, Carl and Mark thanks for your encouraging comments about my work, and again to all who have appreciated it quietly.

 

Moving forward to the control of the clutch I have started to make the forward reverse lever. This lever will need to have some ability to be adjusted.To give just the right amount of pressure to the clutch spring. The geometry of the fulcrum points is critical.

 

The strength of the coil spring is also one of the items that might need a few reworks to get right as well. The whole physics of springs and their construction is no doubt a science, but from my practical point of reference, a trial and error method will have to suffice. So I will see if it works.

 

I rummaged through the scrap box until I found the right bit of brass to cut the lever out of. I used the vernier height gauge to lay out the shape, then pre-drilled all the holes while it was rectangular this makes it much easier to get them square to each other.

 

 

the cutting was done with a fine blade in the jewelers saw. I have already started to file the surfaces to the final shape.

 

 

The keeper rods are now set into the gearbox these were turned up from some free machining 1/8th inch hex stock, at first I left the heads as a hex bolt but they were too big and interfered with the pressure collar. so turned them into cheesehead screws. the spring was wound from some .020 music wire, I used the number drill series of drills as the arbor to find the correct size to finish up with a 3/16th internal bore the third attempt produced the correct diameter, it was a number 21 drill.

 

 

The lower pivot point to which the lever connect to will be mounted on the back wall of the oil pan below the prop shaft, and will be able to be threaded forwards and backwards to give the adjustment.

 

 

There will be a connecting link from the lever to the clamp on top of the clamp ring.

 

Michael

 

 

[michael mott]

Thanks for the likes.

 

I used a trick I employed when filing up connecting rods on my model steam locomotive, and that is to use a hardened button as a filing guide.

 

 

 

 

The top of the handle ended up being hand filed I had originally intended to turn it in the lathe by holding the lever in the four jaw chuck, it caught and bent so after straightening it I used needle files sandpaper and steel wool to clean it up.

 

 

Michael

[SJSoane]

 

michael,

 

Wow....it looks as detailed as full size. Amazing.

 

Mark

[Bedford]

Absolutely beautiful design and workmanship there Michael. It all makes perfect sense and is such a simple elegant concept typical of the age.

 

On a side note, just looking at that heavy flywheel supported by quite a thin crankshaft, are you concerned about the weight of the flywheel forcing the crank out of true over extended periods of non use? I have no experience with such small machines so I realise it may never be an issue but I know the diesel engines my brother works on must be kept rotating by way of an electric motor even when not in use otherwise the cranks will sag and they then have to run them with the motor for a week or so to get the crank true again before they can start it.

[cog]

Michael,

 

That is some fine metalwork. I cannot even see the handle has been bent. Amazing job

[Mirabell61]

Looks great Michael,

 

I`m not sure if you mentioned it before, but is the engine foreseen for running on fuel ?

 

Nils

[captainbob]

beautiful work as always.

 

Bob

[michael mott]

Mark, thanks, once I get this gearbox working smoothly I can move on to the pistons and con rods.

 

Steve, yes the simplicity of the early machinery does have some advantages in the smaller scales, thanks for you compliments. Regarding the bending of the shaft I had not considered it, and am not going to worry about it.

 

Carl, thanks it took a while to get it looking well.

 

Nils, I am thinking that it will run on the fuel used for glow plug engines or Colman camp fuel.

 

Bob thanks.

 

Thanks for all the folk who added likes.

 

I will be doing some more tinkering with the link and lever today.

 

Michael

[michael mott]

I have got the gearbox to the point where I can now move on to the driving portion of this engine namely the pistons and associated gubbins.

 

 

 

 

First I needed to machine up some blank pistons these are .311" (7.89mm) in diameter and .372" (9.52mm) high

 

these were then set into a fixture to drill the wrist pin holes and to machine the squarish hole inside.

 

 

 

they are fiddly little things to work with, popping the O ring on is easy getting the ring off is another story.

 

 

 

they slide up and down nicely in the cylinder head.

 

 

 

Merry Christmas everyone

 

michael

[SJSoane]

 

This is so inspiring to see, Michael. I didn't know such a thing was possible.

 

Merry Christmas!

 

Mark

[cog]

Michael,

 

What material did you make them from. It looks like aluminium, but I can hardly imagine that will stand the tooth of time considering the job it is expected to do.

 

You and you family, have a marvelous Xmas and a healthy and happy new year

[michael mott]

Mark thanks.

 

Carl most of the model engines use aluminum pistons including the ones that I saw in the ship engines thread that I linked to.

 

Merry Christmas everyone

[popeye the sailor]

awesome progress Michael.......very well done!