E-gad, he’s making another one of those crazy pop-up things

[90LX_Notch]

Craig-

I learned something today, thank you.

-Bob

[Kim]

Very interesting process for making the ratchet.
Kim

[Craig DeShong]

Thanks for stopping by.  Bob & Kim, thanks for your comments.

With the ratchet behind me I started on the pawl.  Below is a drawing of the part so you can see what I’m making.



 I found a piece of 3/8th inch cold rolled steel in my inventory that was a good size fit.  Here I’ve drilled the center hole and then followed that with several profile holes that will define a few of the concave curved surfaces.
 


Next I used the rotary milling head to profile a concave and convex surface.


Yet another concave surface.


With the same set-up I’m profiling a few straight sections.



Now I’ve rotated the vice to profile some of the straight edges that aren’t at zero or 90 degrees to the mill table.



Using the rotary milling head again to profile another curved edge.



Finally cutting the part off the stock.



Now a view of the completed pawl; along with the remaining pieces of the mounting hardware.



We all love videos; so here is a video where I review the model to date and explain some of the more interesting aspects of it.
<a href="https://www.youtube.com/watch?v=Wie0GDr8VkY" target="_blank">http://www.youtube.com/watch?v=Wie0GDr8VkY</a>

[Admiral_dk]

A very informative video - thank you     

[Dave Otto]

Lots of progress Craig, everything is looking very nice!

Dave

[Art K]

Craig,
Ditto what he said. Looks good great progress.
Art

[propforward]

That is really great - very impressive approach to make a complex part.

[Craig DeShong]

Per, Dave, Art, Stuart; thanks for your encouragement and comments.  Thanks also for those who just silently stop by to see the current happenings.

I’ve spent the past week carving on a 2 ½ x 2 ½ x 1 5/8th inch piece of cast iron; attempting to make it, at least, somewhat resemble the casting on the full size engine.  Just so you can get an idea of what I’m trying to achieve; below is a rendering of the part from my CAD software.




There were lots of steps in machining this chunk of material and I documented most of them so here we go….

First off was sizing the piece to the above mentioned dimensions; then a bit of drilling, tapping, and slotting as you see below:


Next I used a ¼ inch end mill to form these major recesses in the face of the piece.



A few more recesses in the face of the piece.  This is all just cosmetic work.



Now I employed my rotary milling head for form some of the curved surfaces on these recesses.



Here I give you one of the few photos I took of working the back of the piece.  Pretty much the same procedure as on the front.



Now I’ve turned the piece on its side and am drilling the exhaust port as well as tapping the mounts for the exhaust flange.  This is a rather peculiar setup- a vice mounted on a turntable.  In the next photo you’ll see the purpose.  I’m trying to minimize the setups in working on this part.



The top of this boss has a slight taper.  Here is where the turntable comes into play.



With the boss tapered I need to form the curved surfaces on the top and bottom.  Again I’m using my rotary milling head.


With the exhaust boss finished it was time to do the same on the intake boss- located on the other side of the part.  Here I’ve drilled the gas and air ports, as well as drilled and tapped the flange mounts.



The same procedure as on the exhaust port, I’m adding the taper to the intake boss by rotating the rotary table four and ½ degrees.



The rotary milling head completes the milling of the boss.



Now it was time to cut away the material to fit the slide valve.  I’ve been waiting to do this till now so that the part would have the rigidity needed to perform the above milling steps.



The last steps were to cut the concave surface at the rear of the part.  I was contemplating using a rotary table for this, thinking it might be a bit much for the rotary milling head; but I went slow and took many, MANY passes and all worked out well.


After a bit of clean-up, below is a view of the finished part as well as a mock assembly on the engine frame.

[Vixen]

Craig,

That is one lovely piece of work. It looks just great       

I bet you are pleased with the result

Mike

[crueby]

Very good job on a complex shape!

[RReid]

What a lovely bit of machining!

[Kim]

Wow!  I'll say - that's a very complicated part there. Came out beautifully!
Kim

[Dave Otto]

Nice work Craig!

Dave

[Craig DeShong]

Mike, Chris, Ronald, Kim, Dave; Thanks for the complements.  There is quite a bit of satisfaction in making a difficult part and having it come out respectably.  Mike: yes, I am quite pleased.  Thanks also for those who just stop by to see the progress.

I thought it was time to get a little paint on the model.  Choosing a color is always a major decision point for me.  I could have just decided upon black… that was the original color of all the engines from the factory; but this IS a model and I was thinking that a little distinction was required.  Since I take my models to the shows here in North Carolina (usually tractor shows… but the folks running the shows always appreciate a little variety), I’ve found that “attention attracting colors” helps with crowd interest and:  I do have my 3rd gen Otto Langen painted black.  I was hoping for a deeper color than what I achieved but I think I’ll stick with it:  it’s been growing on me over the last few days.


With the valve body behind me it was time to turn my attention to the valve inner parts.  First was the backplate as seem below.


This part doesn’t occur on the full size; it is integrated into the valve body.  I’ve chosen in all my Otto Langen models to make it a separate part.  The front face of the back plate faces the slide valve and I definitely need an air-tight union between the two.   Making the backplate a separate part, I can use my surfacing machine to achieve a mirror finish on the front face of the backplate.  This part is internally ported and drilled to accommodate the fuel, air, and exhaust passages.

Next to build was the slide valve itself.  Mechanically it would be better if the slide valve weren’t ported all the way through since were I to do this it would not necessitate another air-tight union between the front of the valve and the front plate.  Having the valve cut through takes all the guess-work out of adjusting the position of the valve in the valve body.



Lastly I give you a close-up of the completed valve.

[fumopuc]

Hi Craig, a very nice progress. It is coming together.