Mount Trapezium

[uuu]

The 1/8 x 3/16 bush is a standard size: https://simplybearings.co.uk/shop/p2102001/AI0203-02-Imperial-Oil-Filled-Bronze-Plain-Bearing-Bush-1/8x3/16x1/8-inch/product_info.html

Not that a quick search brought up your width.

No harm in making it thicker.

Wilf

[Jasonb]

Make the hole in the steel part, larger if you want but not really needed. Loctite a solid "bush" into the hole and then once set proceed to form the hole in the bush. It will effectively give it a much thicker wall so no risk of the OD growing as you ream the hole.

[redhouseluv]

Thank you both

I ended up making the hole and bearing bigger and everything was looking fine up until I tried to fit the pivot into the yoke; I think the heat from the soldering must have closed the gap between bottom edges as I can't think why else the slot would not be pararllel top to bottom?

I had to make the pivot a little thinner and after a little fettling of the yoke, I have a nice fit ......phew....I didn't fancy making the yoke again!!

One more bearing to go for the bottom yoke .......job for tomorrow!

[redhouseluv]

Also I'm confused by the grub screw, what is it doing, holding the bush into the bearing or should it go all the way through to the shaft - atm I have it holding the bush, easy to correct if needed?

[Jasonb]

It is doing nothing, you are meant to screw the piston rod into the hole

You probably got a bit heavy handed when you screwed the yoke to the jig. Even if not excessively tight when the metal gets hot it can be deformed by screw or clamp pressure. So always be careful to just do enough to hold parts in place particularly if vbrass or bronze as anymore can see them bend.

[redhouseluv]

It is doing nothing, you are meant to screw the piston rod into the hole

I clearly left my brain behind on my travels 

[PaulR]

It is doing nothing, you are meant to screw the piston rod into the hole

I clearly left my brain behind on my travels 

World's shortest piston rod!

[redhouseluv]

I clearly left my brain behind on my travels 

World's shortest piston rod!
[/quote]

I know, it's embarrasing, I blame the jetlag! 

I'm approaching the last few bits of the build, looks like there's the bottom yoke bearing and cover plate, flywheel which needs to a keyway broached and keyway made, then gaskets and assembly. Hence asking on your thread Paul about cutting bolts to length as this has a lot of them which I'll have to do quite soon

[Jasonb]

Unusual that you have a lot of bolts. In general most of Anthony's engines use studs and nuts as that is what the ful size ones used. I hardly ever use bolts particularly on a scale engine.
 

[redhouseluv]

Apologies, you are correct, lots of studs - I have bought lengths of threaded bar which need cutting to length 

[redhouseluv]

Very little progress today, made the bearing cover plate and attempted the bearing brass when I discovered a mystery. The drawing top right shows a overall width of the brass to be 0.312" which is the same width as the yoke.  There is no way the bearing brass can fit into the yoke with that measurement.

I think the drawing should have shown the outer width to be 0.375", the inner to be 0.312" therefore leaving 0.031" for each of the 'slidy bits' (technical term  )

Ho hum, start again tomorrow..............

[Jasonb]

I think that might be down to me I drew them both at 0.312" but looking at the plate that goes at the bottom the lower yoke should be 1/4.

Should be possible to mill 1/32" off each side as leaving it wider will have a knock on effect with the crankshaft

[redhouseluv]

Hi Jason

Do you mean mill 1/32" of each side of the lower yoke for the whole length (blue lines) or should I just reduce the section which holds the bearing (red lines)? I don't think it'll make much difference visually as the edges of the bearing will mean the edges of the yoke?

If the you think the leaving the width at 0.312" will impact the crankshaft rotation I guess the blue option is the only way

I'm just concerned about damaging the yoke at such a late stage given all the work we have all put into it!

[Jasonb]

A lot will depend on how all the bits come together. The protruding bearing does ensure that the crank will not hit the yoke but it only needs a couple of though clearance. So you could mill the red area and just take a very small amount off the crank side of the yoke which could be done by filing.

Maybe do the red and have  a trial fit and see how things go before doing anything else.

Green shows the clearance the 1/32" of bearing gives and the pink is what could git when the crank is horizontal. Another option would be to skim a bit off the crank which can be done by holding the shaft in the lathe.

[redhouseluv]

Thanks Jason  - I'll go step by step starting with the Red option and and see how it goes