Author Topic: Murdoch-Aitken "Steeple" engine  (Read 5845 times)

Offline derekwarner

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Re: Murdoch-Aitken "Steeple" engine
« Reply #30 on: October 14, 2021, 02:58:23 AM »
There you go....open the image & it is a vertical engine  :wine1: ...I do not understand why the thumbnail persists to be on it's side  :killcomputer:

Is this a twin cylinder steam engine driving a DC generator?
« Last Edit: October 14, 2021, 03:07:07 AM by derekwarner »
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Offline Jasonb

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Re: Murdoch-Aitken "Steeple" engine
« Reply #31 on: October 14, 2021, 07:03:32 AM »
Bit more than a twin, I suppose you might call it a twin triple tandem compound as it has two sets of triple compound cylinders in a tandem (axial) alinement so six cylinders in total

Offline scc

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Re: Murdoch-Aitken "Steeple" engine
« Reply #32 on: October 23, 2021, 06:54:08 PM »
Made a start on the columns, set up in the 4jaw on the  little Clarke, machined all the round bits and finished the ends to length. I had already marked out and centre drilled the small ends. There was a chucking spigot on the large end.......took a load of photos and tried to upload last night :headscratch:     Earlier I had removed the camera battery to recharge forgetting that when battery is replaced everything reverts to original settings which are not pc friendly :cussing:      so no pics.   I milled the ends to size today as seen in these new pics. Simply set the cutter to centre level then drop the table half the dimension required. Both ends now done.  I was surprised by the amount of metal that needed removal, but the castings machined very well. I shall leave the flutes as they are...maybe a little smoothing.          Terry

Offline Admiral_dk

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Re: Murdoch-Aitken "Steeple" engine
« Reply #33 on: October 23, 2021, 07:53:34 PM »
Shame about the camera - but at least you got shoptime  :ThumbsUp:

Offline Kim

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Re: Murdoch-Aitken "Steeple" engine
« Reply #34 on: October 23, 2021, 11:29:07 PM »
Well, the columns as you show them now look great!  I'm sorry we didn't get to see the other work on this though.

There is often tools you can use on a PC to convert the raw images from a camera to JPG.  What format does your camera store pics in by default?  If it's just a size thing then there are definitely many tools available to re-size (that is, if you're interested anyway :)).

Kim


Offline scc

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Re: Murdoch-Aitken "Steeple" engine
« Reply #35 on: October 24, 2021, 09:17:35 PM »
Cheers Folk!    Found the  flatest surface and cleaned up with a light milling. I then turned it over to mill the base. This and the top flange both need a lot of thinning to get the piece to final size. The top will need a small end mill to navigate round all the "lumps", not looking forward to that stage.          Terry

Offline Jo

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Re: Murdoch-Aitken "Steeple" engine
« Reply #36 on: October 25, 2021, 07:44:42 AM »
Morning Terry, you are making good progress on your "Steeple"  :).

I don't normally use a milling cutter to clean up castings. Just hand files, a Dremel and sometimes my old hand engraver to encourage bits out of the corners ;)

Jo
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Offline Jasonb

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Re: Murdoch-Aitken "Steeple" engine
« Reply #37 on: October 25, 2021, 08:13:15 AM »
I was about to say similar. Unless the casting is very over size I would have expected the machining to be minimal only needing to flatten the bottom so it sits well on the columns and then on the top just the central pad for the cylinder and the two for the crosshead guides (steeples) and probably a spot face for the 4 nuts

Or are you just thinking of taking a pass around the outside of the flanges to straighten them out as shown in green in which case you can just file the internal corners square rather than use small cutters
« Last Edit: October 25, 2021, 08:17:37 AM by Jason S Ballamy »

Offline scc

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Re: Murdoch-Aitken "Steeple" engine
« Reply #38 on: October 25, 2021, 08:25:03 PM »
I would agree   but....... The dimension from the bottom face (top of columns) to the mounting face for the crosshead guides is shown as 0.75"
I have already machined the bottom face as much as I dare.....0.072"thick on the flange. When I measure from this face to the top I get 0.855".
If I then remove the 0.105" reqd the top flange will be too thin. :shrug:  It may be possible to further reduce the bottom flange AND modify the bottom of the crosshed guides :thinking:  otherwise some adjustment of upper dimensions will be required.           Terry

Offline Jasonb

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Re: Murdoch-Aitken "Steeple" engine
« Reply #39 on: October 25, 2021, 08:38:23 PM »
I see what you are dealing with now. Another option would be to clean up the cross head mounting pads and then turn it over and machine the bottom flange right off to give a thickness of 0.688" and then add a new flange from 1/16" thick material. This may well be quicker and easier than trying to mill all round the top features and still end up with a thin top flange.

Interesting to look at the general arrangement drawing which seems to shows a narrower portion below the bottom flange. But then again that also shows the usual 24 flutes to the columns so don't know how well that relates to what you actually get.

What does your casting look like it will machine to Jo? assuming you are allowed to touch it.
« Last Edit: October 25, 2021, 08:42:52 PM by Jasonb »

Offline Jo

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Re: Murdoch-Aitken "Steeple" engine
« Reply #40 on: October 25, 2021, 09:05:06 PM »
I'd leave it where it is Terry.

If you recall there are some known "features" on this engine one of which is the crank hits the bottom of that plate and it is suggested we grind a bit underneath so it clears so a bit more space is worth keeping for now   :)

Write yourself a note and keep it with it (or on it) to remind you that it is over thick and by how much ;)

Jo
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Offline scc

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Re: Murdoch-Aitken "Steeple" engine
« Reply #41 on: October 25, 2021, 09:52:34 PM »
I  think I will go with that Jo :ThumbsUp:   Terry

Offline Jo

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Re: Murdoch-Aitken "Steeple" engine
« Reply #42 on: October 25, 2021, 09:56:49 PM »
I was just allowed another look at the casting  ::)

The key distance is from where the cylinder sits to the bottom of the cross head guide. It looks like you just need to make the top flat where the cross head guide goes so it is at the same height as the outer surface of the layer you were measuring to and then take the top surface down so it is the required 7.14mm up. There looks to be a couple of mm spare  :)

Jo
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Offline Jasonb

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Re: Murdoch-Aitken "Steeple" engine
« Reply #43 on: October 26, 2021, 07:11:52 AM »
You would probably want to check that the cross head does not bottom out in the slot if making the distance from crankshaft to guides plus 0.105", or at the very least does run equally to each end.  This would also affect eccentric rod length, overall height of governor assembly, etc as you are changing the height above the base for the shaft and bracket mounting. Also if cylinder is sitting higher up you will want to look at piston rod length so you don't hit a cylinder cover.

Would be worth drawing out the basic overall heights of the parts and checking for clearances etc at TDC and BDC so it does not come back to bit you at a later stage. If you only have pencil and paper then make the conrod assembly from a separate bit of card so you can try it at different positions over the main drawing, ditto eccentric rod.
« Last Edit: October 26, 2021, 07:19:40 AM by Jasonb »

Offline scc

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Re: Murdoch-Aitken "Steeple" engine
« Reply #44 on: October 26, 2021, 01:27:07 PM »
Thanks people :cheers:   Terry