ABC crankshaft

Hi one and all

This is the first time that I have used this new format so here goes.
You may have read about me making new bevel gears , in the current newsletter, well whilst checking the motor I found one of the big end journals had been hard chromed and some of it has come off. I now know you cannot hard chrome a roller bearing face. So here is the questions
Does anybody know an alternative way to repair a damaged big end journal ?
Does anybody have a spare crankshaft ?

If I cannot find a replacement or repair this one I shall have to make a new crankshaft as well !

Kind regards Andrew Cox

Hi.
Thought that I would keep you up to date.
I have now rebuilt the worn crank shaft by grinding the damaged journal undersize and making oversize rollers. I ended up with 10 rollers 8.6 mm diameter in place of the original 11 rollers 7.95 mm diameter. The motor is all assembled but not started as I am now rebuilding the gearbox with the new bevel gear set

I do now have a spare crankshaft which is also ground undersize, but not as much as mine, which is available if anybody needs one ?

Thank you for the update and good to hear you have found a solution.
this is something many of us are having problems with.
If you like, feel free to publish the crankshaft in the "Parts" page. Maybe I should rename it but that's supposed to be the real place where all members can advertise and request parts

Hi
Following on from the crankshaft story I now have a spare crankshaft which has had the journals ground to the same size as each other but are undersize. So all you need to do to use this crank is to make oversize rollers, which is not hard to achieve.
I have attached a picture so that you can see the condition of the crank, it is coroded but is still very usable.
So if some body needs a crank shaft let me know.

Kind regards Andrew Cox

Andrew,
As a more general question, how would you go about making oversized rollers or who would you use?
regards
Ian

Hi Ian

Making rollers is quite easy.
Simply use a good quality tool steel ie. D2.
Turn a "stick" of 5 or 6 long roller blanks leaving about 0.1mm for grinding and only part off to half depth and put a extended center in each end. So you end up with a length of 5 or 6 blanks held together by a smaller diameter , if I knew how to do a sketch I would give you one.
Then send them to a professional heat treatment company to harden and temper to 60 - 62 RC.
Next get a cylindrical grinder to grind them to the required diameter.
Next cut them to oversize length with a slitting grinder wheel, so that you now have the rollers with rough ends.
Make a simple fixture to hold on the diameter and surface grind the ends to the required finished length.
Then grind the corner radius to suit, you can either do this by hand or by a cylindrical grinder.
BINGO you have all the rollers you need, and spares.
I hope this helps, have fun.
Kind regards Andrew