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Author Topic: Stuart MTB 1B - questions?  (Read 560 times)

DBS88

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Stuart MTB 1B - questions?
« on: June 27, 2020, 09:48:53 PM »

Here is a photo of my one hundred year old Stuart MTB 1B 180, twin cylinder single acting engine that I am hoping to put back into steam. Before I can do this there are a few things that I need to find out. I believe the engine had a wet sump with splash lubrication to the crank and lower cylinders. The engine and valves move freely. So your help with the following would be appreciated.
1) The type and quantity of oil used in the sump?
2) The settings for the valve timing? under air the engine currently rocks back and forward rather than continuously rotating
3) Each piston has two grooves, are they for piston rings/graphite cord or are they left empty to carry oil to lubricate the upper cylinder?


The engine was designed to be high reving and to use superheated or flash steam, any advice, help will be greatly appreciated, thank you
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rhavrane

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Re: Stuart MTB 1B - questions?
« Reply #1 on: June 28, 2020, 11:12:46 AM »

Bonjour,
1 - have never seen il in a sump, so I wold suggest an oil lubricator in the flow of the steam pipe : https://www.youtube.com/watch?v=ucnvfTI86lg
I have not this specific machine but a friend who has a Sun uses a grade 480 steam oil, I would kindly suggest you to do the same.

I buy it there http://www.anton-vapeur.fr/liste.php?cat=17&mr=Accessoires%20Moteurs%20Graisseurs and I am sure your would find it closer.

2 - Sorry, no experience

3 - The answer depends on the number and the size of the grooves. On one of my D10, I had three thin grooves, less than 0,5 mm and my friend replaced them by one for a 1 mm diameter Viton O'ring : https://www.youtube.com/watch?v=V1nfERma9MI
I have neither no experience with graphite.
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Jerry C

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Re: Stuart MTB 1B - questions?
« Reply #2 on: June 28, 2020, 11:42:24 AM »

I googled this engine. It says the bottom end is splash lubricated by oil in the sump and the pistons and valve gear are lubricated by a displacement lubricator in the steam line. No data on type of oil though. It was commonly use with flash steam and powered generators and water pumps. Very powerful for its size.
Jerry.

KNO3

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Re: Stuart MTB 1B - questions?
« Reply #3 on: June 28, 2020, 01:22:43 PM »

Oil in the sump should be steam oil, because it will get mixed with water while running. Besides the engine is also going to need a steam lubricator to lubricate the valve and cylinders.

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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #4 on: June 29, 2020, 09:23:22 AM »

I too thought steam oil to be the most likely to use in the sump but having done a bit more research and now spoken to Stuart’s it appears that a light engine oil was used in the sump with the sump being filled to a level where the crank splashes into the oil to create a mist. So will try it with some 20/50 .
The slide valves and top of the cylinders were lubricated via the steam line.


The engine is confirmed as being from the early production run so dating from 1910-1914


As for the valve timing, looks like I am going to have to experiment, so any hints and tips would be most welcome.


Will post more photos when the engine is disassembled
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frazer heslop

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Re: Stuart MTB 1B - questions?
« Reply #5 on: June 29, 2020, 10:18:25 AM »

From that era they may have used a castor oil like Castrol R30 or in later times a straight 20 or 30 grade oil .It is still available from Castrol or a 220 bearing oil available from Morris lubricants. This is what I use in my Clayton and used to use in my 6inch Sentinal steam wagon
Although 220 is graded for total loss Iv not had a problem and my engine leaked that much they nearly were total loss
cheers
https://www.morrislubricantsonline.co.uk/bearing-oil-220.html
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #6 on: June 29, 2020, 07:37:35 PM »

Great tip, thank you Frazer, the Morris Lubricants look to be perfect.


As promised here are pictures of the disassembled engine showing the slide valve, the sump, crank and cast iron pistons.


Next job is to take off the cylinder head to check the ports - however as you will see from the photos some of the screws are sheared so this may take a while - more photos to follow - think I have found the reason why the engine is not currently rotating will update when I know for sure


As before any help with the valve timing settings would be most welcome
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ballastanksian

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Re: Stuart MTB 1B - questions?
« Reply #7 on: June 29, 2020, 08:53:37 PM »

Steam oil has lanolin in it and is very viscous, so would probably not be suitable for your Big ends. But squirted into the cylinders, the vitamins and dinosaurs make it a good lubricant where the viscosity is not easily lost where the mechanism is hottest. Live steam enthusiasts like Frazer use ratchet style pumps linked into the drive mechanism of locomotives etc to apply a measured amount of Steam oil on each rotation.


Regarding your timing, it sounds like it is 90 degrees out and so the slide valves are opening in such a way that it is causing the rocking back and forth of the pistons. Is there a lot of air escape during running off the compressor?
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #8 on: June 29, 2020, 11:14:11 PM »

Well couldn't put it off any longer, the cylinder head had to come off, luckily the thought of doing it was worse than actually doing it. The screws with heads undid without too much of a fight, that just left the two that had sheared off! Fortunately the cylinder head was persuaded past one then I was able to rotate the whole head which undid one stud/stump, the second stud gave in fairly easily after that so job done.


Next jobs are to clean it all up, put it back together, set up the timing and get it running properly.


That just leaves the dilemma - to paint it or leave it natural?  and if painted what colour?
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steamboatmodel

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Re: Stuart MTB 1B - questions?
« Reply #9 on: June 30, 2020, 02:03:50 AM »


I have seen two of these painted one in British Racing Green the other in Naval Blue, both with gold pinstripe. Others I have seen were ether plain unpainted or polished.
Gerald.
PS If you are going to run it with super heated steam you have to paint it with high temperature tolerant paint.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #10 on: June 30, 2020, 07:39:45 PM »

Having removed the broken screws I need to replace them and to be honest, most of the screws look a bit scruffy so may as well replace them all - now that poses another question? What type of thread was used in 1910? was it BA or Whitworth or something else? The small screws appear to be 0.086 inches dia and the larger ones 0.126 both appear to have a fairly fine thread - any ideas?
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ballastanksian

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Re: Stuart MTB 1B - questions?
« Reply #11 on: June 30, 2020, 08:34:13 PM »

I think Stuart reside in Bridport Dorset and they might be able to inform you best on the threads etc.


Indeed my memory is pin sharp thisevening  %%


Here: [size=78%]https://www.stuartmodels.com/p/contact[/size]



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Martin [Admin]

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Re: Stuart MTB 1B - questions?
« Reply #12 on: June 30, 2020, 08:56:59 PM »


Topic renamed on request -  :-)
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frazer heslop

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Re: Stuart MTB 1B - questions?
« Reply #13 on: June 30, 2020, 09:27:27 PM »

 You never know with these old engines. The BA system came into use around 1890/1900
1/8 whit is 40 tpi
3/32 whit is 48 tpi
5 BA is 43 tpi and has an OD of 0.126
8BA is 59.1 tpi and has an OD of 0.086
https://www.tracytools.com/thread-gauge
cheers
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SteamboatPhil

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Re: Stuart MTB 1B - questions?
« Reply #14 on: July 01, 2020, 06:14:13 PM »

The one thing I have noticed is you do not appear to have a drain for the sump as you will need to flush the engine after running on steam (on my sun engine I opened up the sump hole and tapped 3/8 BSB) Also I used Hypo 90 gear oil in the sump (if it still exists  {:-{ )
RE the threads, the very early engines were I believe 3/32 then moved to 5 & 7 BA
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #15 on: July 02, 2020, 07:34:35 PM »

Thank you for the help to date -
Re the threads have now tried to use a couple of thread gauges to no avail, so have no resorted to practical means, I tried both a 5BA and an 8BA neither of which fit, so on to the 1/8 and the 3/32 whitworths next, heres hoping.


Re the drain plug you are correct, theres also no way for the crankcase to breath or for filling and topping up with oil either!!! so need to do more research as to whether or not these were usual or whether they were modifications that people added for themselves.

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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #16 on: July 06, 2020, 10:19:14 PM »

Have now confirmed the screws that hold the sump on are 1/8 Whitworth. So assume the rest are also Whitworth so now trying to locate some suitable 3/32 Whitworth screws for the cylinder head and for the valve cover - they appear to be as rare as hens teeth!!! Have spent a few hours searching the internet and talking to suppliers- have found one that will make me 200 at a cost of £130 - so for now will keep looking, if you know someone with 20 x 3/32 whitworth screws then please do let me know thank you
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derekwarner

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Re: Stuart MTB 1B - questions?
« Reply #17 on: July 06, 2020, 11:59:02 PM »

Some may say it would be committing debauchery,  :o  but an alternative to a British course thread would be to consider a fine thread of Continental heritage {-)

1/8" Whit = 3.175mm......an M4 x 0.5 = 3.5mm tapping drill….[the only downside is the 5.5 AF hex......which could simply be accommodated]

One can never understand why so many [including Jaguar] persisted in using slotted head bolts where it is near impossible to gauge or attain any reasonable induced torque
Derek
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SteamboatPhil

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Re: Stuart MTB 1B - questions?
« Reply #18 on: July 07, 2020, 08:07:30 AM »

This might just be your lucky day, I have


9 off 3/32 Whit hex head (1/2 long)
10 off 3/32 R/H Whit head (1/2 long)
3 off 3/32 hex head Whit (3/8 long)


Yours, just PM me your address


Derek...shame on you.....metric..... >:-o
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #19 on: July 07, 2020, 08:38:52 AM »

Thank you that’s both kind and generous, have sent a pm, it’s appreciated
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IanJ

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Re: Stuart MTB 1B - questions?
« Reply #20 on: July 07, 2020, 02:34:01 PM »

Hi,


With regards to 1/8" whit which is 40TPI; 1/8" ME (model engineer) thread is also 40TPI. ME taps & dies are readily available. Try www.tracytools.com and EKP supplies have fixings that could help.


Cheers


Ian
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #21 on: July 07, 2020, 10:17:01 PM »

Thank you for the advice and support on the thread sizes it is appreciated. The 1/8 threads are now taken care of with new 1/8 th Whitworths, it the smaller size in whithworth at 3/32 that was causing difficulties, this has now been resolved with the kind help of a fellow Mayhemer, Steamboatphil, who had some. I am really happy about this because it means the engine stays nearer original. I had been considering drilling out and re threading in a larger size, as suggested, then replacing the screws with studs - thankfully, hopefully that’s not currently going to be necessary.
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DBS88

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Re: Stuart MTB 1B - questions?
« Reply #22 on: July 12, 2020, 07:35:02 PM »

Heres a progress update and a few more photos. Have had a bit of time over the weekend so started to clean and degrease the cylinder head and valve chest. I used some gunk, a tooth brush and then some wire wool. Still deciding whether or not to paint it. Also took the time to clean up the machined faces being careful not to remove all the original machining marks. When I took it apart there were no gaskets, having cleaned the mating faces up, they will now wring together so I know they are flat, smooth and should give a good seal - lets wait and see how leaky it is under steam before we get too carried away!!! Next will be the cylinder block and sump.
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