| Making up the crank
shaft
1st October 2010
I have decided that I will make up the
crank shaft as the next part. This will be a fabricated crank using Loctite
603 high strength, oil tolerant retainer which can cope with a diametrical
clearance up to 0.1 mm (about 0.003"), has a Service temperature range:
-55°C to +150°C, and a Fixture time on steel of 8 minutes to join
the various parts. To ensure that the Loctite 603 is fresh a new supply has
been ordered.
A 7/8" mild steel bar was machined to
diameters of 20mm at one end and 17mm the other. This was carried out by
machining between centres so that the trueness of the machining was maintained.
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| The crank off set (web) will be drill
and bored to fit the 20mm part of the shaft. |
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| 8th October 2010
Big end of crank
Another simple turing exercise. As the
part will be fixed by Loctite 603 there are two grooves on each of the surfaces
which will be located in the crank webs. The grooves enable a good spread
of the Loctite to occur. |
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| 9th October 2010
The webs of the cranks were cut from
bar that had been reduced from 12.7mm to 11mm as per the plans.
The holes to be a good snug fit on the
big end and the main shaft were then machined. the two parts were locked
together by a 4BA bolt through the centre of the web. |
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| When the boring was complete a test
assembly of the parts to ensure a good fit was tried. Then Loctite 603 was
applied to one end of the big end and one of the mating faces of a web and
allowed to set. Similarly one web was secured with Loctite 603 on the main
shaft at the correct position from the reduced part.
The the two parts were introduced to
each other and more Loctite applied to both parts and they were moved into
place and then finally pinched home in the vice such was the fit.
The parts will be left, in the warmth
of the house, for a minimum of 24 hours before the centre section of the
main shaft is cut away to allow an sufficient time for 100% strength to be
achieved. |
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| 10th October 2010
The centre of the crank was cut away
and then the surplus filed flat. |
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| Here the crank is set in the main
bearings with bearing cap in place and the split bearing is set on the big
end.
You can see that the harshness of the
square corners has been removed and then may eventually be rounded even
more. |
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| 17th October 2010
The splash guard was not included in
the original kit of castings so this was purchased at the Midland Model
Engineering Exhibition. |
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| 20th october 2010
I was able to collect my con rod based
on the drawings but altered slightly so that copyright of the supplied
plans was not breached, from the water jet cutters
in Staplehurst.
The piece was originally 19mm thick so
each side was milled 1.5mm all over and then to reduce the size further each
side up to near the big by a further 2mm each side. |
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| Here the con rod is being held to
drill out the little end to size to take the bush. |
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| Then drilling was carried out to
provide the tapping holes for the studs to hold the big end together.
It was first drilled 5mm for the M6 tap
and then 6.3mm to the half way mark for a clearance.. |
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| The con rod then had id marks centre
popped on two sides and then cut in half. I am pleased to say that the big
end bearing fit very well. |
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| 22nd October 2010
The big end stud holes were tapped to
take the M6.
The oilway to the bearing was drill and
then counter drilled for tapping M4 for the oiler. The bearing was then cross
drilled to meet the oil way.
New studs were made up as the big end
is bigger on the rear side and than in the drawings.
The whole lot was assembled and tightened
up and there is not a sign of binding.
The nuts are temporary as it needs to
eb lock nutted with two nuts so these nuts will be cut down and another pair
made. |
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| 12th November 2010
The crank now has had its keyway milled
out. The way it was held is shown in the photo and is now completed. |
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