Author Topic: 1802 Bell Crank Engine  (Read 79362 times)

Offline Roger B

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Re: 1802 Bell Crank Engine
« Reply #30 on: December 01, 2014, 08:04:11 AM »
This looks to be yet another interesting build to follow along  :ThumbsUp:  :ThumbsUp: I'll be there  :popcorn:  :DrinkPint:
Best regards

Roger

Online Jo

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Re: 1802 Bell Crank Engine
« Reply #31 on: December 01, 2014, 12:51:03 PM »
As its gunmetal why not slice it down the middle and solder back together and add a bit of height where required at the same time.

Not a good idea as Bottom cover which slides within the sides of the Cistern is also over sized and if you reduced the width of the cistern it would fall over the outside. No it is another of those cases of identifying the mating surfaces and making them match each other and hopefully getting equal material where needed.

These are the instructions for the nuts and bolts given in the drawings, they miss out all the other sizes you also need to make :-\

Jo

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Online Jasonb

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Re: 1802 Bell Crank Engine
« Reply #32 on: December 01, 2014, 01:26:53 PM »
Well you could do the same with the condenser & its cover, how wide is the actual casting and whats the wall thickness

Online Jo

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Re: 1802 Bell Crank Engine
« Reply #33 on: December 01, 2014, 02:31:35 PM »
The bottom cover goes on the bottom of the cylinder.

Jo
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Online Jasonb

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Re: 1802 Bell Crank Engine
« Reply #34 on: December 01, 2014, 04:14:46 PM »
my mistake. In that case just cut the two legs off the bottom cylinder cover and resolder. If the legs are too wide then by the time the cover has been turned to dia you may not get the nuts in to the two fixings that are on centre line

Online Jo

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Re: 1802 Bell Crank Engine
« Reply #35 on: December 01, 2014, 04:39:15 PM »
Or as it is a casting, for which no measurements are critical, find a measurement that all the castings will work for  ;).

Jo
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Online Jo

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Re: 1802 Bell Crank Engine
« Reply #36 on: December 01, 2014, 07:55:46 PM »
The first thing we need is a reference, the easiest being the base but because both sides of the casting has a draft angle it is necessary to pack the two sides parallel. Not forgetting that the casting is hollow so longer pieces of steel have been used either side to spread the pressure of the vice:



It was next clamped onto a rather large angle plate and the two ends cut flat and square. Using the reference base and the same end it was now possible to square up the casting, machine the top to height (or below height as the casting allowed :-\) mill the tops of the stands deep inside the cistern for the condenser and to take the outside brackets to height.



At the far end on the top you may just about be able to see that I have also taken out the two corners this is to add some ears as part of the next stage. I also milled the insides of the part just under the cylinder to take the bottom cover.

Nearly half way on this bit  :)

Jo
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Offline philjoe5

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Re: 1802 Bell Crank Engine
« Reply #37 on: December 02, 2014, 12:06:59 AM »
Jo,
Being quite the novice at machining castings I have a question.  Since the base of the base is going to be your reference plane, machining it seems critical to me.  How do you align the casting in the vise to ensure you'll have enough material on the other sides to machine those surfaces true?

Cheers,
Phil
« Last Edit: December 02, 2014, 12:37:26 AM by philjoe5 »
If you pick up a starving dog and make him prosperous, he will not bite you. This is the principal difference between a dog and a man.  - Mark Twain

Offline Maryak

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Re: 1802 Bell Crank Engine
« Reply #38 on: December 02, 2014, 01:38:19 AM »
Hi Phil,

Normally with any casting one fiddles about with it to see if it is suitable to be machined, (i.e. its not too small and the observable surfaces have no blow holes etc.). Next a suitable datum is determined and marked on the casting. The casting is set up for machining using the datum line/points for reference.

In Jo's case where the 1st cut is to mill a base a second line would be offset from the datum and the casting set up to this line then milled to the line. Once the base is machined the casting is returned to the marking off table and everything re-measured from this new datum.

Well that's my way; and my working with castings has only been with 12":1'

HTH

Best Regards
Bob
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Online Jo

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Re: 1802 Bell Crank Engine
« Reply #39 on: December 02, 2014, 07:53:36 AM »
Hi Phil,

Yes as Bob says I had to fiddle around with it balance this bit being over sized and that bit under. My final decision was actually where someone had already had an attempt at squaring up the bottom it was within 0.5mm of where it needed to be as a starting point.

So squared up with a level it was faced down by the 0.5mm. There was still a couple of slumps but they will be underneath so will not be seen. Having removed 2mm on the length to get both ends square it is now 1mm short and the area around the cistern where the beading is supposed to go will be lower than the drawing says  :shrug:

That beading :headscratch: the kit came with what I expected a reel of D shaped beading that is normally put on using soft solder and some G clamps as I did on my Clayton Cab. But the drawing shows something that looks more like a piece of brass that has had its edge rounded

Jo
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Online Jasonb

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Re: 1802 Bell Crank Engine
« Reply #40 on: December 02, 2014, 10:30:38 AM »
Don't think they make the 1/2 round beading down to 1/16" so its out with the file to round off the side of some flat strip then fit that to the top of the casting, thats why I queried if you had allowed for that strip when you said the sides were low as it effectively adds 1/16" to them.

Did not think these castings were supplied with any bar stock, is that something teh previous owner had stockpiled for te project

Online Jo

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Re: 1802 Bell Crank Engine
« Reply #41 on: December 02, 2014, 11:19:53 AM »
Did not think these castings were supplied with any bar stock, is that something the previous owner had stockpiled for the project

You are right these casting sets do not include bar stock but when I picked these up second hand the previous owner had added them  ;D


You will appreciate that as a modified second hand set they were very expensive (90 :disappointed:) but not as bad as another set of castings that have promised to come along to tempt me on Saturday :slap:   

Jo
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Online Jasonb

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Re: 1802 Bell Crank Engine
« Reply #42 on: December 02, 2014, 01:33:58 PM »
Anything that might tempt me ::) though I expect they won't make it past his pickup point :(

Having said that I think I enjoy the fabrication more than working from castings so can see me going more down that route unless its something very desirable.

J

Online Jo

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Re: 1802 Bell Crank Engine
« Reply #43 on: December 02, 2014, 02:42:39 PM »
:hellno:

They are castings, best you avoid them  ;)

It would be nice to get a set of Otto Langen patterns into the Foundary then my retirement casting sets will be ready and waiting for me :embarassed:

Jo
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Online Jasonb

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Re: 1802 Bell Crank Engine
« Reply #44 on: December 02, 2014, 03:44:24 PM »
Don't think I'll get to do any on the Otto until over xmas, thats if I don't work with a client being away for 3 weeks its tempting to get on in the empty house.

Best you get on with those BB1 patterns to go with them :LittleDevil: