Author Topic: 3 1/2" Rob Roy (Read 4012 times)

Dalboy · « **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.

Dalboy · « **Reply #1 on:** January 24, 2023, 04:00:34 PM »

Part two

Dalboy · « **Reply #2 on:** January 24, 2023, 04:02:03 PM »

Part three

Dalboy · « **Reply #3 on:** January 24, 2023, 04:03:41 PM »

Part four

Dalboy · « **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

vtsteam · « **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!

Kim · « **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

rick41 · « **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

Dalboy · « **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>

Quote from: rick41 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

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

Dalboy · « **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

Dalboy · « **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

)

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

springcrocus · « **Reply #11 on:** January 28, 2023, 10:33:19 PM »

Regards, Steve

TimB · « **Reply #12 on:** January 29, 2023, 11:05:55 PM »

Every little bit is a step forward!!
Keep up the good work.

Tim

Dalboy · « **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.

Dalboy · « **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.

Kim · « **Reply #15 on:** February 02, 2023, 05:25:22 PM »

That's a lot of work for those little guys! But they are important pieces, so good that you've got them done!

Kim

Dalboy · « **Reply #16 on:** February 22, 2023, 06:26:50 PM »

Back on the Rob Roy even if it is only making a pair of slide valve gland nuts, as I have been busy starting the vegetable garden off ready for the growing season. No pictures but it does feel great being back in the workshop hopefully more time in there

Dalboy · « **Reply #17 on:** February 27, 2023, 06:47:30 PM »

Started to machine the ports on one of the cylinders today. Just need to drill the exhaust and 5 mounting holes which I will do while it is still set up in this orientation. Other jobes keep getting in the way so work is a little slow.
I have a white board whi9ch I draw the part onto with all the measurements in imperial decimal as the plans are in imperial fractional. Not only that but it means the plans stay clean.

Dalboy · « **Reply #18 on:** February 28, 2023, 03:16:34 PM »

Well that is one step forward and two steps back so I have now ordered a pair of new cylinder blocks as I am not happy with the out come of the ones I have done so far rather than mess about trying to save them I decided to start again.
Not a total waste of time as I have learnt things from making them.
While waiting I will make some other parts or even do some work on the Farm Boy engine

Kim · « **Reply #19 on:** February 28, 2023, 05:23:54 PM »

Sorry for the mishap. That's never any fun

So, what happened? The last picture of the machined ports looked good to me. $:-\$

Kim

Dalboy · « **Reply #20 on:** February 28, 2023, 06:11:56 PM »

Quote from: Kim on February 28, 2023, 05:23:54 PM

Sorry for the mishap. That's never any fun
So, what happened? The last picture of the machined ports looked good to me. $:-\$

Kim

I had already machined the surface too low before but was doing a work around, then this time for some silly reason I used the wrong size mill to do the outer ports they should have been 3/32" but I managed to do them 1/8" which means they are 1/32" over wide. New ones now ordered as well as a long series 3/32" bit.
At least it will solve two problems at the same time.

Kim · « **Reply #21 on:** February 28, 2023, 08:16:43 PM »

Yeah, that's a tough one to recover from. You could do a valve plate to cover the face and make that have the correct size openings. I've seen that done before. It might also help address the issue with the surface being too low. But then again, sometimes it's just best to try again.

It's your engine, so you get to decide what the best path is. And I'm with you either way! We've all been there, done that.

Looking forward to seeing your progress when you get the new casting and the new end mill!

Kim

Dalboy · « **Reply #22 on:** February 28, 2023, 11:33:40 PM »

I did plan to do that with the face that I machined too low and yes I could do that but I would not be happy I would rather start from scratch and have it right

Kim · « **Reply #23 on:** March 01, 2023, 04:48:46 AM »

Sounds like the right call to me!

Kim

springcrocus · « **Reply #24 on:** March 01, 2023, 07:59:31 AM »

Sometimes it can be down to cost. That looks like a very expensive lump of yellow metal in the vice.

Commiserations, Steve

Dalboy · « **Reply #25 on:** March 01, 2023, 03:40:56 PM »

Quote from: springcrocus on March 01, 2023, 07:59:31 AM

Sometimes it can be down to cost. That looks like a very expensive lump of yellow metal in the vice.

Commiserations, Steve

Total £67 for the two including postage. At least (touch wood) I know they will be right

How is the triple coming on

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Author Topic: 3 1/2" Rob Roy (Read 4012 times)