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Author Topic: Stuart MTB 1B - questions?  (Read 7145 times)

tghsmith

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Re: Stuart MTB 1B - questions?
« Reply #25 on: July 17, 2020, 12:18:54 am »

the timing would be correct 1 out 5 revolutions,, most look like a matched set of gears in both material and tooth count,, have you seen this  https://modelengineeringwebsite.com/Stuart_Turner_1.html
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #26 on: July 17, 2020, 07:56:21 am »

Hi Jerry the bevel gears take the rotation of the crank through 90 degrees up the side of the engine to a scotch crank that converts rotary movement to linear movement to operate the slide valve. Since These are the only two gears I believe they need to be 1:1 ratio to maintain the timing, so hoping to see photos and or get measurements and tooth count. It would be nice to keep this as close as possible to what was intended
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malcolmbeak

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Re: Stuart MTB 1B - questions?
« Reply #27 on: July 17, 2020, 10:09:55 am »

I have an MTB 1, but it has a piston valve. I was told many years ago that there were a few produced like this. Having Googled Stuart MTB 1B I found an excellent article about the Stuart single acting engines. It would seem that yours is an early version (there was an earlier still version that used a face cam, lever and spring return but they were not too reliable) I have shown photos of the early, later and mine.
Mine has brass bevel gears with 15 teeth. It is well worn and I haven't tried it on steam, but it is so free that I can easily blow it over.


Malcolm
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ooyah/2

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Re: Stuart MTB 1B - questions?
« Reply #28 on: July 17, 2020, 06:07:37 pm »

Dave ,
Here is the timing diagram for the current Sun engine model, I don't suppose that Sturt Turner could tell you what the bevel gear dimensions are.


I don't have the actual DRG for this engine but the pics I have show that the bevel gears look the same size.


Try setting the timing as per the picture . if it works I would not put the engine together again without gaskets which can be made from brown paper well oiled.




George.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #29 on: July 20, 2020, 08:33:11 pm »

Malcolm and George, thank you for your helpful replies, they are appreciated. I have now located (found) a couple of suitable gears (16 teeth) and slid them roughly into place to check they work and how they look. The screws for securing the cylinder head and valve chest are on the way so will be able to assemble the engine and use the timing settings later this week, so good progress is being made.
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tghsmith

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Re: Stuart MTB 1B - questions?
« Reply #30 on: July 21, 2020, 12:22:11 am »

keith appleton has several you tube vids on this type of engine,, talks about oil filled sumps....
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #31 on: July 29, 2020, 10:12:41 am »

Here is a delayed update. Have been busy on other projects whilst waiting for a few bits to complete this engine, oh and a new arrival to the fleet has also been a distraction. Have now degreased and cleaned the rest of the parts. I obtained a 3/32 whit worth tap and have now cleaned up the threads, the screws have arrived, thank you to Steamboat Phil. I am just waiting for two new gears to arrive, the gears I showed you last time were from a mechano set!!! they may have done a job, but I want to do this restoration sympathetically and as well as I am able to. Still trying to decide whether to leave the engine with its natural finish or to paint it?
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KNO3

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Re: Stuart MTB 1B - questions?
« Reply #32 on: July 30, 2020, 12:53:18 pm »

Nice work. I guess you'll need to paint the steel parts, or they will go rusty.
You could probably use any bevel gears that fit, provided they have the sarme number of teeth.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #33 on: August 24, 2020, 11:06:37 am »

Its been a while since I worked on this engine, because I have been waiting for parts, in the meantime I have been learning a lot from two new arrivals to the fleet, a tug and a torpedo destroyer . To progress this engine I decided to go for some new gears rather than the meccano ones, they have now arrived. They have 4mm holes, however the crankshaft has been ground/turned to an odd size of 0.163 inches, so had to order a drill to enlarge the hole in one of the gears so that it would fit, so another delay. Have now placed the gears on the shafts and checked there operation. So now need to put the new toys to one side and get on with completing this engine. Interestingly one of the new toys has the last development of this MTB 180 engine in it, a Stuart Sun engine.
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KNO3

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Re: Stuart MTB 1B - questions?
« Reply #34 on: August 24, 2020, 09:22:55 pm »

They fit perfectly!
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grendel

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Re: Stuart MTB 1B - questions?
« Reply #35 on: August 25, 2020, 01:58:04 pm »

I was about to say those gears mesh properly, the meccano ones have a 30 degree face, so wouldnt mesh properly together.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #36 on: September 22, 2020, 05:35:32 pm »

Firstly, thank you for all the help received, without your support it would have been a lot more difficult to have saved this lovely engine. Also thank you for your patience in waiting for updates, as some of you know I have been distracted by new arrivals to the fleet, but today got on with assembling the engine and setting the timing. I am happy to report that the engine started immediately and continued to run smoothly at a decent rhythmic pace from a meagre air supply of approx 5 -7 psi- the best that my airbrush compressor could manage with this engine. Whilst my aim is to have it in steam that will have to wait til I have a boiler on the bench that I can connect it to. The engine is currently assembled with out gaskets, which appears to be how it was originally made, and appeared to be air tight, but as we know steam and higher pressures are likely to show up any weakness in the joints.
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KBIO

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Re: Stuart MTB 1B - questions?
« Reply #37 on: September 22, 2020, 06:43:25 pm »

Hello!
This is a lovely piece of collection! :-))
I do not see no segment ring on the pistons. Is-it normal ?
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #38 on: September 22, 2020, 07:55:13 pm »

Re the grooves in the pistons, for this engine, the grooves are there to cary oil from the wet sump to lubricate the cylinder bores, they are not there for piston rings - I did wonder about this myself and research led me to this conclusion. Having run the engine today with a sump full of oil the splash lubrication system seems to be effective
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derekwarner

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Re: Stuart MTB 1B - questions?
« Reply #39 on: September 22, 2020, 10:32:19 pm »

The fact of the grooves in a single acting single acting engine or a double acting engine in the exhaust phase of the stoke/cycle relates to a combination of both Boyles and Charles Laws........[The Combined Gas Equation]


https://www.thoughtco.com/definition-of-combined-gas-law-604936#:~:text=The%20combined%20gas%20law%20combines,is%20equal%20to%20a%20constant.&text=where%20P%20%3D%20pressure%2C%20V%20%3D,)%2C%20and%20k%20%3D%20constant.\


Just a little light bed time reading  {-) ........the fact that the labyrinth rings trap and distribute lubrication oil is absolutely a secondary bonus :-))

Alternate steam applications also benefit in a similar manner ....


https://www.sciencedirect.com/topics/engineering/labyrinth-packing#:~:text=The%20seal%20steam%20system%20enables,between%20the%20inside%20and%20outside.


Derek
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Derek Warner

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ooyah/2

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Re: Stuart MTB 1B - questions?
« Reply #40 on: September 28, 2020, 04:54:12 pm »

Dave,
Continuing your thread on the old Stuart twin cylinder engine.
I did some research and found that I had posted a Thread (. https://www.modelboatmayhem.co.uk/forum/index.php/topic,31619.0.html ) on a similar engine that I had done some refurb on, I can't remember where my engine came from but when refurbed it was sold to a collector on e-bay.
The pics that I have posted may give you some idea as to whether you paint it or not, click on to the pics for a larger image.


I am surprised that there is no Crank case vent so lubrication to the cylinder is by splash pressure in the Crank Case and pumps oil from the sump to the underside of the pistons and also lubricates the small end in the piston.
The ring grooves are there to collect oil and steam from above to help in the sealing of the pistons to the bore. You will find that all of Stuart engines that don't have piston rings rely on this method, the sump oil is normal Auto engine oil, as I can't see any method to replenish the oil in the sump, I have a feeling that one of the central Crank case fixing bolts when taken out allowed oil in and it was total loss system when running,

I personally when building Stuart Models withought rings use Silicone "O" rings and never have had any failures.


If you go to the end on the posts on the 2nd page  you will find a History of this engine and how it developed into the "Sun"


George.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #41 on: September 28, 2020, 05:32:23 pm »

George, thank you for the link, its an interesting read, and confirms your engine as a No1 MTB. As you point out in your thread the design of the cam with the steel ball follower was not the greatest, so gave way to the MTB 180 and MTB 1B. From my research I believe the MTB 180 to be made between 1910 and 1914, so yours was probably earlier. As you say these engines went on be further developed. Sitting on my bench waiting its turn for some attention is one of those developments its the No1a MTB engine which as you can see needs a good clean and some TLC but hopefully will look stunning when its done. The final stage was the Sun engine which has holes drill in the top of the casing for filling the oil and relieving the pressure, I am currently working on getting these Sun Engines running. So all in all this MTB 180 refurbishment has been a good learning experience for these next engines.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #42 on: October 28, 2020, 01:47:50 pm »

As you know I have been wondering whether or not to paint my MTB 180 engine and if so which colour, I have seen one in black and gold and now this one in green, both look really good. NB the green one sold recently for £549.

I am leaning towards leaving the engine as bare metal, clean oiled cast iron has a certain authentic appeal. In the mean time I am hoping to run it on steam soon.
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rhavrane

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Re: Stuart MTB 1B - questions?
« Reply #43 on: October 28, 2020, 08:01:18 pm »

Bonjour,
Green is the official color of Stuart engines : https://www.stuartmodels.com/
I can imagine that black and gold is nice, but it is note the right color  ok2
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Raphaël
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KNO3

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Re: Stuart MTB 1B - questions?
« Reply #44 on: October 29, 2020, 11:55:04 pm »

Paint it the colour you like. Cast iron looks good painted and it will be much better protected from rust.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #45 on: November 01, 2020, 09:41:02 am »


I have now re found the video of the black MTB 180 so or completeness here is a picture of a MTB 180 that has been painted black and gold and a link to the video of its refurbishment and then running


https://youtu.be/9Pd8EkOtRXE
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KNO3

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Re: Stuart MTB 1B - questions?
« Reply #46 on: November 01, 2020, 10:30:17 am »

Looks very good!
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rhavrane

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Re: Stuart MTB 1B - questions?
« Reply #47 on: November 01, 2020, 12:43:29 pm »

Bonjour,
Beautiful, black and gold instead of gree,, it does not matter whand you see its power on the video  :-))
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Raphaël
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #48 on: December 03, 2020, 06:15:12 pm »

While tidying up today I found the video I took of the of this engine running on air, I thought it was lost. The pressure was about 7 psi, thats about as much as my airbrush compressor will do. The engine ran pretty fast and very smoothly, its not screwed down to the bench, it just sat there purring away, quite mesmerising to watch. Any way enough chit chat heres the link
  https://youtu.be/p5didhgcjZI


Hopefully I will be running it on steam before Christmas so hope to post another video then.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #49 on: January 10, 2021, 03:18:11 pm »

Well today was the long awaited day, I have a boiler on my bench that I am getting ready for another project, it seemed a shame to waste the steam so I rigged up some pipe and an oiler an ran my MTB 1B 180 for the first time on steam - this day has been a long time coming. Next time I run it it I will screw it down so that the full rev range can be enjoyed. Anyway here is the link to the video, thank you for your help, support and patience waiting for today. https://youtu.be/euHzoMmPScA
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