Enlarged Rocking Engine Build

[Ross]

Looks nice Ross. What's the large diameter on it? Just trying to get an idea of the scale of the thing

Steve

Thnks Steve

The o/d of the cylinder is 1 inch.

And the ID is .511 inches.

I'll try and remember to take a photo of the parts next to a coin or something, but there's not many of them about!

[Ross]

Hi everyone.

Today I put the radius onto the piston and made it fit the bore.

It was VERY easy to go undersize, the piston  fits and turns in the bore nicely its not as snug as it probably could be but I think it should be good enough I can always adjust when it is all together.

[zeeprogrammer]

Looks really good Ross.

[swilliams]

Yes - coming along nicely Ross

I'll try and remember to take a photo of the parts next to a coin or something, but there's not many of them about!

   hopefully that improves in the not too distant future!

Steve

[NickG]

Or use an M&M - it's an international standard of scale!

[Ross]

Hi everyone,

Today I made two crank wheels.  They just need the off set hole drilled through the for the crank pin.





I also shortened the bolts for the cylinder plate.

[NickG]

Nice 1 Ross, getting there. 

[Ross]

Hi everyone,

Finally got back onto this today.

First I made a mandrel for clamping the crank wheels while drilling the offset holes.






I drilled the first hole with no problems. But on the second I over tightened the nut and stripped the thread, I had to put the 3 jaw back on and skim the face.



Clocked and drilled.





Then I drilled the holes for the grubsrews to fix onto the crank. And. Threaded M3.

[NickG]

Good work there Ross, glad to see you back on it 

[arnoldb]

Good to see you back on the build Ross 

If I may offer a couple of suggestions...
When possible, have the flange section of the workpiece press against the headstock end of the mandrel - that adds additional friction, and will also leave a hole with less burrs to remove after drilling.  It also means you don't have to clamp down that tightly on the nut and strip out the threads, and with a piece of ordinary photocopy paper squashed in between at the chuck end, you'll get an even better friction fit with even less torque needed on the nut.  It will also eliminate flex on the screwed section, and you will end up doing a more accurate job.  And lastly, rather than threading the entire section on the mandrell, turn most of it to a good fit for the hole in the workpiece, and thread it to leave only a couple of thread turns inside the workpiece to allow you to tighten it down.  Threaded sections are usually smaller in diameter than the actual hole, and having an entire threaded section adds a lot of unnecessary slop.  Just a couple of very cheap cents from my part of the world 

Kind regards, Arnold

[Ross]

Good to see you back on the build Ross 

If I may offer a couple of suggestions...
When possible, have the flange section of the workpiece press against the headstock end of the mandrel - that adds additional friction, and will also leave a hole with less burrs to remove after drilling.  It also means you don't have to clamp down that tightly on the nut and strip out the threads, and with a piece of ordinary photocopy paper squashed in between at the chuck end, you'll get an even better friction fit with even less torque needed on the nut.  It will also eliminate flex on the screwed section, and you will end up doing a more accurate job.  And lastly, rather than threading the entire section on the mandrell, turn most of it to a good fit for the hole in the workpiece, and thread it to leave only a couple of thread turns inside the workpiece to allow you to tighten it down.  Threaded sections are usually smaller in diameter than the actual hole, and having an entire threaded section adds a lot of unnecessary slop.  Just a couple of very cheap cents from my part of the world 

Kind regards, Arnold

All good points Arnold, and I'll use them next time around!

[Ross]

Hi everyone,
 
I ordered some aluminium for the engine frame a while ago, and it arrived today

I had a go at filing the edges of the engine frame square. And being probably the worst filer in the world even using a square and taking off the high spots, I was tearing my hair out! I don't think I can get any straighter than what I've ended up with!





The only problem being is that the rectangles are now 2x1.5 inches they need to be 2x1.25 I don't particularly fancy trying to file the longer edge square but I'm worried that the extra .250" height will dwarf everything else! Ideas?

Ross

[Bezalel]

Hay Ross
 
There is probably more experienced guys who could improve on my suggestion but you could stack the two plates together side by side in the 4 jaw, two jaws on each side off the stack, then face off ( use HSS as its an interupted cut) reduce to about 1.3" then flip them over ensuring they are flat against the chuck face then take off another 50 thou - hay hay! flat, parallel, square and correct size.
 
Bez

[dalee]

Hi,

I can also vouch for that method. I've done things like that a few times and it's fast and accurate.

dalee

[steamer]

Wot Bez and Dalee said!

Let the lathe do the filing!....

Dave