Mount Trapezium

[redhouseluv]

Okay  - steady as she goes, we're making progress

The bearing brass area is reduced to 1/4" and the brass fits nicely. I can't tell from the drawing, but I'm guess I should remove 0.031" (may be 0.029") from the red edge (photo 1) so the bearing drops down, then do the same to the blue edge (photo 2) to allow the bearing cover plate to traverse and fit?

[Jasonb]

The drawing only shows the bottom and sides being cut away not the top, so just the blue

[redhouseluv]

More progress......

The bearing brass and cover plate are now fitted to the yoke after the mods, thanks for the assistance

Whether luck or judgement I never loctited either the crankshaft or the crank pin to the web which should in theory make 2 operations easier:

1. The crank pin needs opening up to fit the bearing - I think its going be a delicate operation with very light cuts otherwise bent pin will result.

2. The crankshaft needs a keyway slot cutting into it to accept the key for attaching the flywheel

[redhouseluv]

Crankpin question

I managed to get the crankpin to fit by thinning the sides of the bearing, not by increasing the gap in the pin and it now rotates nicely.

I made a quick video and was wondering if I need to loctite the crankpin at all? The reason being is that without loctiting it I get a degree of movement which will allow me to adjust the gap between the yoke and the web and provide clearance, but will everything work ok? I appreciate that I will need to loctite the shaft to the web at some point soon.

https://youtube.com/shorts/t2ghaJoddEo?feature=share

[Jasonb]

You really want it fixed so that the pin rotates in the bearing rather than rotating in the yoke.

Try it on the assembled engine to set the position.

[redhouseluv]

Broached the keyway in flywheel and cut the slot on the crankshaft

I have no drawings left aside from 1 which is for the key itself, so I think unless I've missed something, all pieces will have been made. I guess I'll find out during 1st assembly.

Before that I need to construct a temporary base, so that'll need some thought......getting there!

[redhouseluv]

The final piece of the jigsaw has been machined; its the first time I've used an accurate method for cutting a key (a previous Jason thread) and the result is good.

I'm wonderering whether to call it a day or fettle more to eliminate the gap indicated by the red line and risk going too far? If the answer is fettle more, where should I remove the material, from the bottom straight edge or the inclined top edge?

[Jasonb]

I usually remove material from the sloping top. Blue the surfac ewith a sharpie and then when you tap it lightly in the marks on teh surface will show where it is touching.

Before you do that make sure the key is sitting right fown in th eshaft keyway. From the photo it does not look like it is right down, possibly tight on the width of the keyway

[redhouseluv]

Good spot, I'm glad I uploaded the pictures, otherwise that would have been missed, will check for that now!

To my great relief (yes, I was anxious  ), the trapezium rotates and clears all potential contact points, with the piston and guides connected (see video)........phew!!!

https://youtube.com/shorts/70hns8nnSHk?feature=share

Also I think the yoke to crankweb clearance is ok, its small but is there; I think its time to commit and loctite the crankshaft and crankpin to the crankweb as I have to be certain. Also this will allow me to position the outer bearing block and cutout for the flywheel in their correct location

[redhouseluv]

Much better thanks, I'll wait until the end before tapping the last bit in........onto making the base

[redhouseluv]

Started on the base today - I take it there's no other way to cut metal sheet other than drilling and milling? Took a while but nothing compared to the immense effort by Kim on his scroll clock!!

[Michael S.]

It's a lot of work, but it looks great.

Michael   

[PaulR]

Started on the base today - I take it there's no other way to cut metal sheet other than drilling and milling? Took a while but nothing compared to the immense effort by Kim on his scroll clock!!

Piercing saw or handy hacksaw followed by files? 

[crueby]

Or drill corner holes then run the mill down the sides.

[Kim]

As Michael said, it's an effort, but your results look great!
Kim