Author Topic: Hick Crank Overhead engine  (Read 1028 times)

Offline AVTUR

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Re: Hick Crank Overhead engine
« Reply #15 on: September 10, 2019, 07:07:41 PM »
The decorative feature on the top of the standards is a poor example of the casters' skills. It was one reason why I put the castings aside a few years ago.

I am not sure how, or even if, I am going to correct them. They have already been sharpened up with a file during fettling.

AVTUR
There is no such thing as a stupid question.

Online Jasonb

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Re: Hick Crank Overhead engine
« Reply #16 on: September 10, 2019, 07:45:32 PM »
I think I would mill off the raised vertical details and then go a bit deeper over the whole area. Then machine up a couple of flat strip to fit that can have a series of grooves cut into them and stick them in place with JBWeld. This gives nice square ends unlike the ball nosed cutter option.

Offline Johnmcc69

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Re: Hick Crank Overhead engine
« Reply #17 on: September 10, 2019, 07:48:46 PM »
That's a shame. Cool little feature.
 I like Jason's idea about using a ball end mill there.

 Good progress though!  :ThumbsUp:

 John

Offline AVTUR

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Re: Hick Crank Overhead engine
« Reply #18 on: September 16, 2019, 12:40:05 PM »
After getting them shot blasted I have been giving the standards much thought. So much so that I put pen to paper (fingers to keyboard) so that I do not confuse myself. In the manner of a student to puts the longest, most complex equations into his/her presentation of work to hide the fact that he has done nothing, my ramblings are as follows:

The front standard has two bosses for the piston rod guide.

Function
1.   To hold the crankshaft assembly
2.   To locate the piston rod by means of a guide block
3.   To hold the governor spindle bracket
4.   To hold the rocker shaft

Fit: Datum 1 - Horizontal plane provided by base of standard, Datum 2 - Vertical plane provided by face of rear edging on standard, Datum 3 - Vertical plane of symmetry. These planes are orthogonal.
1.   The height from base to plummer block face must be 5.125” ± ?”. The faces must be flat and parallel.
2.   The shelf on the inner face of the standards must be flat for the governor spindle bracket mounting collars.
3.   The face of the piston rod guide bosses must be flat and square to the standard base.
4.   The face of the rocker shaft bearing pads must be flat and square to the standard base.
5.   Holes in bases and for plummer blocks must square or parallel to the datums.

Form is all important, looks count for everything. As far as possible both standards should be identical. I would like to have kept the finish as cast but the casting was so poor. Therefore I think they will be machined all over except for the large recessed surfaces which will remain as cast. I want to keep the height of the edging from the outside recessed surface constant if possible. The finished results may be shot blast again. The frieze at the top of the standards must be prominent. I do not intend to think about them for the moment but I like Jason’s suggestion.

Inspection showed that some dimensions are tight, importantly the height of the standards, while others allow quite a lot of room for machining. There are no critical undersize dimensions. However the rear standard is twisted with the bottom of the right leg forward of the left by about 0.030”.

Machining sequence will probably be as follows:
1.   Mount standard outer face downwards on milling table, using shims to account for the twist in necessary, and skim inside edging to provide Datum 2.
2.   Skim rear of base pads and top platform
3.   Face top and bottom of shelf for governor spindle bracket, rocker shaft bearing pads and top of base pads.
4.   Turn over and mount Datum 2 face against table (again using a suitable block of metal) and skim front of base pads and top platform.
5.   On front standard face piston rod bracket bosses.
6.   Clamp both standards together back to back using spacers and super glue if necessary.
7.   Mount vertically with feet upwards on an angle plate. [Think about Datum 3].

This is as far as I have got recording my thoughts. However it has given me the clarity to start work on the standards.


I have made some progress with the pump parts. The pump should be finished next week and I will give details.

I have also made the all important build stand.

AVTUR
There is no such thing as a stupid question.