Author Topic: Stothert and Pitt in 1/6th (and other) scales  (Read 302321 times)

Offline zeeprogrammer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #15 on: October 10, 2012, 12:23:30 PM »
I really like beam engines and this thread is already proving to be highly interesting.
I'm glad too that you intend to stay original.  ;D
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Offline Jo

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #16 on: October 10, 2012, 12:45:24 PM »
There are 8 leaves and I am thinking positively that should make it easier when I fly cut the leaves using a technique such as suggested by Dave. To give an idea of the size of the item this is it for the 1/12th scale engine, so double it for this one:



I have just found a better photo of the capitals :Love: (and that quality paint work):



I think it would be acceptable to leave the capitals with just the leaves for the 1/12th scale engine but the 1/6th scale needs those inserts. I suppose they could be made separately and then soldered into position  :noidea:.

Jo
« Last Edit: July 10, 2017, 09:23:35 AM by Jo »
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Offline Captain Jerry

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #17 on: October 10, 2012, 01:35:12 PM »
Wow!  Lots of people chiming in with thoughts on this.  Here is my 2 pence.


I see 8 leaves in the full sweep.   My approach is a combination of all of the above.   I see a two part assembly, a red internal cone, and a gold external flower.  The problem that I see is that the petals of the flower get very thin and machining them unsupported will probably distort them.


I would start with a piece of brass for the flower and bore the internal trumpet shape with a form tool.  Then I would turn the matching contour of the red part to match.  Using a contrasting material, cast iron or steel.  Then insert the cone into the bored hole and solder (soft).  Then use a flycutter lake making a small pinion,  cutting through brass and steel.   Then I would turn the outside contour on the brass flower,  the color contrast.  The solder should keep the leaves from distorting.  Then de-solder the flower from the cone.  Now make a new cone without the grooves and put it back in the flower.  You could probably work the inner set of leaves with a small three corner file. 

Here is a 3D PDF that you can rotate and see the profile of the flycutter.


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Offline steamer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #18 on: October 10, 2012, 01:45:16 PM »

For the smaller of the two, I doubt you could even see the inside leaves....

Brainstorming is always fun.


Dave
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Offline steamer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #19 on: October 10, 2012, 01:51:54 PM »
Actually Jo....looking at the close up....I bet if you fly cut the part off axis, you could make both leaves in one go.

In my minds eye, The spindle with a flycutter would be perpendicular to the axis of the column and off axis which could cut the side of the outside leaf and the inside leaf in a plunging cut.

That would get you 8 right sides....you would need to set up on the other side of the column and do the same thing to get 8 left sides.

I see lots of experimentation to get the shapes right...but it could work....do the big one first to get your feet wet...then the small ones

Thoughts?

Dave
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Offline steamer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #20 on: October 10, 2012, 01:58:30 PM »
Jo....if you have a 3D CAD package available...you could save yourself a lot of cut and try by modeling the part with revolved cuts to work out the flycutter geometry and spindle axis location....I suspect you could home in on the right shapes and locations pretty quickly doing it that way.

Dave
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Offline Jo

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #21 on: October 10, 2012, 02:05:18 PM »
Sadly neither do I have a 3D drawing package, nor do I know how to use one :ShakeHead:.

But CJ's plot looks impressive, I was worrying about the leaves being a bit thin, the idea of a sacrificial insert sounds like the way to go.
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I had thought about the two cut approach but making sure the second cut started at the right place is going to be touch and go. I cannot just leave them in the dividing head as I need to do 4 ( +4 ) times the 8 cuts.

Jo
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Offline Captain Jerry

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #22 on: October 10, 2012, 02:11:26 PM »
Here are two views.  The end view gives a look at the fly cutter profile.  My thought of using contrasting material for the sacrificial cone was to make it easier to work the external curve of the flower after cutting the profile grooves.

Jerry
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Offline steamer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #23 on: October 10, 2012, 02:18:59 PM »
Looks like we're gaining on a practical solution! :ThumbsUp:
Dave
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Offline steamer

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #24 on: October 10, 2012, 02:55:13 PM »
Jo....if your not in a hurry....when I finally get my work station rebuilt from the hard drive crash...I'll load up Alibre again and I can experiment for you......but it wont be for a couple of weeks anyway....

Dave
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Offline tel

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #25 on: October 10, 2012, 06:08:14 PM »
Just had a quick dekko at the drawings - it would appear that on the smaller version they ignore the problem altogether.

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Offline Jo

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #26 on: October 10, 2012, 06:11:59 PM »
Dave, I am in no rush I still have my DTC engine to complete.

Tel: Yes I know :disappointed: , but it is one of the key features of this engine.
 
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Assuming we have a workable way forward for the capitals .. the next problem ;D: The beam. I have never made a beam from scratch all the engines I have ever made have been based on castings. The set of castings I have for the smaller engine is missing an important part the curved inner trim to the rim of the beam:




My original intention was to make an inner gusset and then cut two Tee sections which had the correct profile with a slot for the gusset plate. However :ShakeHead: This rim is 14.5mm wide and the outer edge is 3.5mm wide. The quarter round  on the inside of this rim would have a 3.5mm external diameter and 2.5mm inner. But I was concerned about bending it.

Can anyone come up with a better method of making this? I also want to do the same for the smaller engine.

Jo
« Last Edit: July 10, 2017, 09:25:56 AM by Jo »
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Offline tel

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #27 on: October 10, 2012, 06:16:48 PM »
Quote
Tel: Yes I know :disappointed: , but it is one of the key features of this engine.

Couldn't agree more, my friend, it's one of the key reasons I've never started the build.

I'm loving your detail shots tho' - they'll probably be enough to tip me over the edge.
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Offline Jasonb

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #28 on: October 10, 2012, 06:18:12 PM »
For the beam I would go with a steel plate cut to profile, drill for and solder in bosses for all the pivots and also solder on two steel strips for the top and bottom flanges, all done with silver solder.

Then run the moulding in brass, bend and soft solder in place. Bit hard to tell is it a convex quadrant moulding or a concave scotia moulding? If its concave then maybe cut a tube into 4 quadrants. The other way is to use a roundover or bull nose cutter depending on sbape to cut the profile on the edge of a flat strip so its easy to hold and then cut it off with a slitting saw.

Offline tel

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Re: Stothert and Pitt in 1/6th (and other) scales
« Reply #29 on: October 10, 2012, 06:21:21 PM »
concave to my eye Jason. You could probably produce strips with an ordinary round nosed end mill.

I think that your method would be the best way but I would mill shallow grooves down the centre of the flange strips to hold the web in place for the silver soldering
« Last Edit: October 10, 2012, 06:24:38 PM by tel »
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