Kiwi Mk II

[Jo]

Thanks Tjark, that's the sort of jig we needed, we tried measuring it lots of ways each time concerned that the pressure on either end might be deforming the crank 

Jason the two webs are still in line it is the two shafts where they come out of the webs where it all goes 

A new piece of steel has had a couple of 1mm deep surface cuts and is now "normalising". I wonder if I need to hack out the sides as well this time and then let it settle

Jo

[Roger B]

Still following along through your ups and downs     

Have you tried holding one end of the crankshaft in a collet and checking the runout of the other end close to the flange and at the end. If you turn the crank round and repeat it should be possible to determine where the distortion is and maybe correct it. Rather than a plastic hammer I would recommend using the crossslide to apply some pressure.

[Jo]

Hi Roger, yes I know where the distorsion is: the two external shafts are not concentric to each other 

My current plan is to make another, in the meantime I am sticking to simple bits that should not go wrong 

Was the food good/interesting in China 

Jo

[Roger B]

Was the food good/interesting in China 

Jo

This time there were two reasonable European style restaurants near to the Hotel so I stuck to these and avoided the excitement 

Are the two external shafts parallel but not concentric or at an angle? I was able to straighten the first crankshaft for my vertical engine as I described after the engine fell onto the floor    

[Jasonb]

Can't quite see how they would not be concentric as they were turned between ctrs, unless its as I said the two webs habe twisted which would have them parallel but out of line. See sketch

As roger says its more likely to be some form of bend or warp.

If you put one end in a collet  and put a dti on the other if they are eccentric then you should get the same reading all along the shaft, but I expect the reading will increase as you get towards the end. A bit of "cold setting" would be worth a try.

[Jo]

The measurement implies it look like this 

Maybe I should go back to embroidery 

Jo

[Allen Smithee]

Ouch! Is the solid line the measured position and the broken line the intended position? If so please disregard my previous suggestions about bending it back - it won't!

AS

[Jasonb]

Jo if we assume the dotted circle is the one in the collet is the solid one at the end of the crank or where the bearing fits close to the web?

The only way you could have got that if its near the web would have been to space the ctr holes differently

[Jo]

There was plenty of speculation as to what could have possibly caused it on sunday 

The agreement was to make a new one.

Jo

[Jasonb]

But would be nice to know what did cause it so the same does not happen again

[Allen Smithee]

It was obviously caused by local magnetic anomalies, the local magnetic field being distorted by the vast quantities of castings in the vicinity. To avoid a recurrance you must move the castings about 7 road miles from your machine shop. By a happy coincidence my machine shop is just that distance away, so as a favour I'm prepared to take custody of them.

No, don't thank me. I'm just naturally that generous.

AS

[Jo]

That is very generous of you Pete but I was going to try an alternative and add another 1700lbs of American tool steel to the vicinity. Hopefully it is only me that will have a magnetic attraction to it

Of course that will mean I will have to find new homes for C1 and the Prazimat   

Jo

[Allen Smithee]

You certainly pick the most difficult option, but if it works it would be a hard-ingenious solution.

AS

[Jo]

You certainly pick the most difficult option,

I think the term is more expensive 


As more and more of my castings are aluminium I think that there is a greater risk of them exhibiting the Lenz effect and discouraging  any of my (magnetised)  iron castings from leaving me   

Jo

[Stuart]

Jo

The term expensive is a term that is open to conjecture ,I bet the total cost of you casting stash could equal that machine that has a 5c nose and can cut 11 TPI but I think they do need a proper three phase supply to keep them happy or so I have read


All I will say is you canna Tay it with you to the bone yard so enjoy exchanging those shekels for some good iron

Stuart