Author Topic: 3 1/2" Rob Roy  (Read 489 times)

Offline Dalboy

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3 1/2" Rob Roy
« on: January 24, 2023, 03:58:54 PM »
I started this loco last year I will not describe all that has gone on in the past as it will take some time but as and when I progress from now on I will explain what I have been up to.
So the next few posts will have just pictures, by all means ask any questions and I will try to answer them. This is also the first time I have done any model engineering and the first time ever using a milling machine. I have in the past when I was at school used a metal working lathe but that was so long ago and I am now retired.
This will be made at the same time as the Farm Boy engine which I am also making. I know glutton for punishment but I do normally have at least two projects on the go at any one time so that if one comes to a standstill I can work on the second(I have done this even when making wooden models which I explained in my introduction.


Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #1 on: January 24, 2023, 04:00:34 PM »
Part two

Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #2 on: January 24, 2023, 04:02:03 PM »
Part three

Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #3 on: January 24, 2023, 04:03:41 PM »
Part four


Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #4 on: January 24, 2023, 04:04:42 PM »
Part five and this brings it up to date so everything from now is as I make it


Offline vtsteam

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Re: 3 1/2" Rob Roy
« Reply #5 on: January 24, 2023, 04:40:30 PM »
Nice to see all those photo stages together. It gives me a feel for the whole process. Looking forward to your continuation!  :ThumbsUp: :popcorn: :cheers:
Steve

Online Kim

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Re: 3 1/2" Rob Roy
« Reply #6 on: January 24, 2023, 06:01:13 PM »
Wow! That's a lot of work summed up in very few photos there!  It's looking great!

Kim

Offline rick41

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Re: 3 1/2" Rob Roy
« Reply #7 on: January 24, 2023, 08:11:43 PM »
Impressive!  I took me nearly 20 years to finish mine.  If you have not already done so, I highly recommend you do some research on what problems others have encountered when building this engine.  A place to start is "Building a Rob Roy, Model Engineer". One thing I would do is to relocate the exhaust piping from between the valve covers to the front of the valve chest.  It is difficult to install the piping as shown as there is very little room.  The valve linkage cannot be installed per plan as there is a dimensioning error in the plans.  You will either have to move the valve chest or use an offset coupling on the valve linkage.  I would also use different pitch threads on the ends of the valve rods to facilitate timing later on.  There are more, but I cannot remember them all as I am away from my workshop and do not have access to my notes.  When it came to firing my locomotive, I had no success in firing with coal.  My fault as others fired theirs with success.  I converted mine to propane and it runs like a scalded dog!  If you want to see it, just Google "UTube Rick's Rob Roy".  Good Luck! Rick

Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #8 on: January 24, 2023, 11:11:37 PM »
Thank you guys. I will post as soon as I get more done, as many know it will be a long build>


Impressive!  I took me nearly 20 years to finish mine.  If you have not already done so, I highly recommend you do some research on what problems others have encountered when building this engine.  A place to start is "Building a Rob Roy, Model Engineer". One thing I would do is to relocate the exhaust piping from between the valve covers to the front of the valve chest.  It is difficult to install the piping as shown as there is very little room.  The valve linkage cannot be installed per plan as there is a dimensioning error in the plans.  You will either have to move the valve chest or use an offset coupling on the valve linkage.  I would also use different pitch threads on the ends of the valve rods to facilitate timing later on.  There are more, but I cannot remember them all as I am away from my workshop and do not have access to my notes.  When it came to firing my locomotive, I had no success in firing with coal.  My fault as others fired theirs with success.  I converted mine to propane and it runs like a scalded dog!  If you want to see it, just Google "UTube Rick's Rob Roy".  Good Luck! Rick

Thank you Rick yes I know some of the problems people have encountered the exhaust pipe was one of them and also the linkage


Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #9 on: January 26, 2023, 04:23:40 PM »
I needed to make a spacer up for the steam chest as I managed to take a little too much off when machining the cylinder assembly. It is only a case of 1/16" thick piece which can be seen marked out the centre of each of these will need to be cut out so the hole that is drilled in there will be removed. They both also need cutting to length. that is a job for tomorrow
While the mill was set up I set to on the round piece which will become the slide valves as this also need to be 1/16" taller so easier to remake that part completely As can be seen milling one side off the round just need to do the other side the lines are slightly over size as I am rough machining this to size before the final cuts to the correct size all I had was a 2" diameter bar of phosphor bronze bar.
I know it appears like I am jumping around a bit but I will get there in the end


Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #10 on: January 28, 2023, 06:00:14 PM »
Managed a little shop time today as Saturdays I spend the afternoon preparing and cooking a meal for the wife{great for some good point scoring to buy more tools :lolb:)

Anyway as my last post having to make a spacer and remake the slide valves finished sizing the bronze for these today and slotting them out easier to do them in a single block then cut and final machine to length. I made a simple stop to simplify the process, I should get them finished tomorrow.

The black mark is only where I rough marked them and is left over from a sharpie pen


Online springcrocus

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Re: 3 1/2" Rob Roy
« Reply #11 on: January 28, 2023, 10:33:19 PM »
 :ThumbsUp: :ThumbsUp: :popcorn: :popcorn:
  Regards, Steve

Offline TimB

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Re: 3 1/2" Rob Roy
« Reply #12 on: January 29, 2023, 11:05:55 PM »
Every little bit is a step forward!!
Keep up the good work. :)
Tim

Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #13 on: January 30, 2023, 05:49:38 PM »
Thank you guys.

No progress more like a step backwards the slide valves had a little mishap so having to start again also broke the milling bit all my fault but I am sure it will not be the last time something happens like this during this build.

Offline Dalboy

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Re: 3 1/2" Rob Roy
« Reply #14 on: February 02, 2023, 04:45:08 PM »
At last got the slide valves complete after three attempts they just did not want to work out but got there in the end lets hope I have better luck as I go on.


 

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