sleeves/hardness of bores

[abently]

Can't you just machine the ends to your exact size and then nitride it ? Yeah you could machine it out and press in a case hardened section. That would work just fine also.

I assume that there is still going to be an oil supply to the big and small ends with the needle bearings ?

I think your actually going to increase the friction levels rather than decrease it as the crank end theoretically never touches the conrod in the standard arrangement.

[oldcorollas]

needle bearing arrangements are not uncommon in small motors..

a for the 0.5mm thing.. perhaps that will not be strong enough to resist getting out of shape when it is loaded up.. if it is not hard enough, it will sort of peel... maybe it will be ok the main problem is that bearign races need to be REALLY round.. or else the bearing will die quickly... thats why the shells are not usually thin.

can't make crankcase bigger, or clearance the bits in the way 8and than tig a plate around it etc?)

[Sam_Q]

Absently: the reason I didnt want to just make it and have it hardened is because I am paranoid it will end up too hard and snapping. Because I am putting a lot of work into this engine I dont think I could get myself to rebuild it if it failed.

The oil supply for the needles will be via the usual slots in either side of the big and small end for the oil mist to go through.

what do you mean the crank never touches the rod in standard form and how would it be different than what I am doing? Idealy I want to have it just like it is now just with a longer rod.

Corollas: interesting points on the shell, to give some exact specs the pin is 12mm, the inside diameter of the big end is 15mm and there is 0.8mm clearence between the outer part of the big end to the crankcase with a 33mm stroke.

I have looked long and hard at the crankcase and without a heap of welding and some delicate milling its pretty much not an option. I can mill out 1mm on the radius which will mean I should be able to get away with a 1mm thick hardened insert. Might that do?

Oh I want to have about a 14,000 max rev limit so nothing crazy.

Also I thought you guys might be interested in some pics of my progress so far:


part 1 of the barell, more work has been done since



the reed block housing part 1:




Part 2:

[abently]

Theoretically, the oil film is never broken therefore the crank never touches the conrod.

33mm stroke @ 14000rpm = piston speed of ~ 15m.s which is uber safe.

Nitriding only goes a mm or 2 deep and is used by many automotive manufacturers..

What Are The Benefits?

Favoured for components that are subjected to heavy loading, nitriding imparts a high surface hardness which promotes high resistance to wear, scuffing, galling and seizure. Fatigue strength is increased mainly by the development of surface compressive stresses. Hot hardness and resistance to tempering are improved and corrosion resistance is moderately enhanced. The low processing temperature and subsequent slow cooling help minimise distortion.

Typical applications include gears, crankshafts, camshafts, cam followers, valve parts, extruder screws, die-casting tools, forging dies, aluminum-extrusion dies, injectors and plastic-mould tools.

In ferritic nitrocarburising, the resultant compound layer, with good lubricant-retention characteristics, is responsible for the major benefit of high resistance to wear, scuffing, galling and seizure. The diffusion zone contributes improved fatigue resistance if components are quenched after nitrocarburising. An increase in corrosion resistance can be improved upon further by post-oxidation treatment which imparts an aesthetically-pleasing black finish; additional polishing and oxidation steps can yield a surface finish rivaling hard chrome plating, in terms of high corrosion resistance combined with low coefficient of friction.

Typical applications of ferritic nitrocarburising encompass pressings, bearing shafts and cages, cams and crankshafts, gears, bushes, liners, pump components,sintered parts, plastic-mould and extrusion dies and tooling.
Whilst it can also increase the hardness of alloy steels, the influence of ferritic nitrocarburising on the bulk surface hardness of low-carbon non-alloy steels is moderate .Austenitic nitrocarburising allows the other benefits to be combined with indentation resistance by strengthening the substrate beneath the compound

But you can probably do without it and using an insert is more convienient to replace once it becomes non-round after some period.

[Sam_Q]

thats really neat, well that gives me two real options now so once again thanks