Bob J's No.21 Steam Engine (drawings and STP files by Pat J)

[salmonr]

That seems like an awful lot of clearance. .007 is a huge amount. Is that what the drawing says? I would try for a mere .001 and if that is not enough, then enlarge it with a toothpick but start small and add titbits at a time. what is the conrod made from? steel or something else?

Thanks Richard, I think steamchick has explained it superbly.

 

[Steamchick]

Thanks for the info, just one question, when you say steam oil , do steam engines have an oil mixed to steam ?, or does the steam just pick up oil that is lubricating.

Commercially Steam Oil
https://www.hallettoil.co.uk/steam-oils/
is a grade of oil traditionally used for steam engines. VERY viscous (50W??) when at room temperature, and with a vaporisation temperature compatible with steam temperatures to become oil vapour in the steam - as far as I can GUESS? So when steam expands in the cylinder (or valve chest or anywhere else!) the oil becomes condensed and lubricates all those internal surfaces of the engine. In fact when steam condenses too, the incredibly fine droplets of steam condensate (water) and oil mix to become a milk-like emulsion. I know modellers who do not use steam oil in case the thick viscous oil gums-up the engine when cold. But I use it in displacement lubricators as it seems to work fine, and the oilers do a good job of providing a little oil constantly when running. (Measured by the oil consumption when draining condensate after a run before re-filling!).
It smells of - OIL. Walk past any preservation steam loco (full sized or scale) and you can smell the distinctive "steam oil" smell mixed with coal smoke. - Or just the oil if the fire is out.
I heard of drivers using Castor Oil on their track model locos, but, like early (pre-1970s?) racing car and motorcycle racers, suffered diarrhoea afterwards! Who knows what the regular Steam oil does, as it is a mineral oil I think?
BUT if running on AIR from a compressor, use regular air-tool oil from the air-tool shop. It contains additives for resisting corrosion from condensate from AIR. Even though expanded air has a lower dew point than room air. In that case, invert the Displacement Lubricator - using a light machine oil such as 7W "lathe oil", or compressed-air-tool oil. The pulsations of the inlet will draw -in adequate lubrication to resist wear, in place of steam condensate displacing the oil into the steam stream entering the engine.
I make displacement lubricators sometimes, but they can be bought quite cheaply at times - for less than the cost of the brass I have to buy! (See attachment).
https://www.ebay.co.uk/itm/19650483...7779&msclkid=3a4e8886baca1e389d32effcf048c620

N.B. If you wash-out engines after use by using a water displacement like WD40, or silicon spray, or even Paraffin oil, then you MUST lubricate with something that both lubricates and resists corrosion - like car engine oil of a low viscosity (7.5W30 is good - but only really good for preventing corrosion for a month or 2, depending upon your climate? - like in your car engine.) or rust preventative (may be good for 3 to 60 months overwintering in the cold garage?) to avoid "stuck piston rings" or piston, etc. when you next come to run the engine. Unless you have brass or bronze valve chests, valves, rods, cylinders and pistons, etc.
After a good session of steaming engines (e.g. a show day) I seem to spend as much time de-watering engines and re-lubricating after use as I do actually steaming! (Running/idling on a low-supply air compressor).
And I have a couple of small engines that will happily tick-over while I am in the workshop, running on my ex-'fridge compressor. They make good conversation in the background ("toosh, toosh, toosh, toosh, toosh...") - Makes a change from eternal repeats of music + adverts on the radio, especially when I need thinking time for a special set-up or operation.
Happy days!
K2

 

[GreenTwin]

That seems like an awful lot of clearance. .007 is a huge amount. Is that what the drawing says? I would try for a mere .001 and if that is not enough, then enlarge it with a toothpick but start small and add titbits at a time. what is the conrod made from? steel or something else?

If the hole for the connecting rod in the lower cylinder head is not perfectly concentric with the bore, then you can get binding between the lower head and the connecting rod.
If your machining is good, and everything is exact, you can use less clearance.

.

 

[GreenTwin]

As others mention, de-watering a steam engine with WD40 is critical if you run an engine on steam.
If you don't de-water, then the piston and ring will rust solid with the cylinder (don't ask me how I know this).

If I run a steam engine on air, I use a bit of WD40 to get rid of any condensate, but not nearly as much as if I had run the engine on steam.

.

 

[salmonr]

Commercially Steam Oil
https://www.hallettoil.co.uk/steam-oils/
is a grade of oil traditionally used for steam engines. VERY viscous (50W??) when at room temperature, and with a vaporisation temperature compatible with steam temperatures to become oil vapour in the steam - as far as I can GUESS? So when steam expands in the cylinder (or valve chest or anywhere else!) the oil becomes condensed and lubricates all those internal surfaces of the engine. In fact when steam condenses too, the incredibly fine droplets of steam condensate (water) and oil mix to become a milk-like emulsion. I know modellers who do not use steam oil in case the thick viscous oil gums-up the engine when cold. But I use it in displacement lubricators as it seems to work fine, and the oilers do a good job of providing a little oil constantly when running. (Measured by the oil consumption when draining condensate after a run before re-filling!).
It smells of - OIL. Walk past any preservation steam loco (full sized or scale) and you can smell the distinctive "steam oil" smell mixed with coal smoke. - Or just the oil if the fire is out.
I heard of drivers using Castor Oil on their track model locos, but, like early (pre-1970s?) racing car and motorcycle racers, suffered diarrhoea afterwards! Who knows what the regular Steam oil does, as it is a mineral oil I think?
BUT if running on AIR from a compressor, use regular air-tool oil from the air-tool shop. It contains additives for resisting corrosion from condensate from AIR. Even though expanded air has a lower dew point than room air. In that case, invert the Displacement Lubricator - using a light machine oil such as 7W "lathe oil", or compressed-air-tool oil. The pulsations of the inlet will draw -in adequate lubrication to resist wear, in place of steam condensate displacing the oil into the steam stream entering the engine.
I make displacement lubricators sometimes, but they can be bought quite cheaply at times - for less than the cost of the brass I have to buy! (See attachment).
https://www.ebay.co.uk/itm/19650483...7779&msclkid=3a4e8886baca1e389d32effcf048c620

N.B. If you wash-out engines after use by using a water displacement like WD40, or silicon spray, or even Paraffin oil, then you MUST lubricate with something that both lubricates and resists corrosion - like car engine oil of a low viscosity (7.5W30 is good - but only really good for preventing corrosion for a month or 2, depending upon your climate? - like in your car engine.) or rust preventative (may be good for 3 to 60 months overwintering in the cold garage?) to avoid "stuck piston rings" or piston, etc. when you next come to run the engine. Unless you have brass or bronze valve chests, valves, rods, cylinders and pistons, etc.
After a good session of steaming engines (e.g. a show day) I seem to spend as much time de-watering engines and re-lubricating after use as I do actually steaming! (Running/idling on a low-supply air compressor).
And I have a couple of small engines that will happily tick-over while I am in the workshop, running on my ex-'fridge compressor. They make good conversation in the background ("toosh, toosh, toosh, toosh, toosh...") - Makes a change from eternal repeats of music + adverts on the radio, especially when I need thinking time for a special set-up or operation.
Happy days!
K2

Thank you , every day I learn something new.

 

[TrollForge]

If you go to the "Building Them - Plans" section, go to "filter" on upper right, type in "greentwin", under "started by", hit the "filter" button, and you will seen the plans I have posted on this site, which are for the Dake, Bernay, Greentwin, and BobJ's No.21.

I don't do anything commercial; all of the drawings I have uploaded are open-source for non-commercial use only.

I stopped uploading drawing sets because some folks were abusing that and using the drawings for their commercial use.

Pat J.

Thanks a bunch Pat!
If I can ever find a place to set my shop back up, and get the last few repairs & upgrades done to my 130 year old Lathe, I think I want to try the Dake... (not having a mill) it looks like a good place to start.
You didn't answer my last question (at least to my old nerve damaged brain's contentment.) Would it be alright to film the build and post it on YouTube, or would you see that as a breech of the "Not for Commercial Use" clause?
I don't want to run afoul of you or the site.
T.

 

[GreenTwin]

No problem filming and posting on youtube, even if youtube pays something.
We will call that "falling into the gray area" and say that is ok.
.