Help with 'Speedy' valve gear and other issues...

[andyhigham]

I suppose some tank capacity could be sacrificed and make the inner wall double skinned, say a 6mm gap?. Double skinned mugs will keep tea hot enough to drink for well over an hour

[Roger]

Nov 30, 2018 19:52:05 GMT andyhigham said:

I suppose some tank capacity could be sacrificed and make the inner wall double skinned, say a 6mm gap?. Double skinned mugs will keep tea hot enough to drink for well over an hour

This is true, and the same can be said of those awful Polystyrene tea mugs you get from some Service areas. From Doug's tests, the Polystyrene looks viable, and Pete points out that there is a more expensive version of the backing paper that's an even better insulator. Maybe a combination of a small air gap with enough ventilation to let the air escape and then a layer or two of Polystyrene on the back of the tank would be a good compromise. I don't think you need much thickness of insulation if it's Polystyrene.

[Roger]

I've shown these micro sockets before, all of which have a 5mm AF hex on the outside. I've been using them with a 5mm socket for some time, but that's a bit on the big side and the sockets keep falling out which is annoying.

So today I decided to make the little driver on the right which is just a piece of Silver Steel with a 5mm AF pocket in the end. That was drilled and then machined with a 2mm then 1mm slot drill, 6mm deep.

The bottom of the hex pocket has a 3.2mm diameter hole into which a Neodymium magnet is bonded with Loctite.

The top end also has a 3.2mm hole which also has a magnet at the bottom of it. The piece on the right goes into the same hole and the magnet stops it falling out when it's inverted.

20181130_205849 by Roger Froud, on Flickr

It goes together like this so that the top spins round like those watchmaker's screwdrivers do. Simple but effective.

20181130_205912 by Roger Froud, on Flickr

[David]

Very nice. 1 & 2mm cutters in silver steel? What spindle speed and feed rate was that?

[steamer5]

Hi Rodger,
Spent many happy hours driving a Speedy that used to visit my home track. Never had a issue with the water getting to warm, water on at the beginning of the day, top up tanks as required, water dribbling out the injector when not running, worked great!
As an aside, this Speedy had quite a few mods to the LBSC drawings......too long ago to remember what, but the one that does stick is sight glasses on the side tanks visible in the cab! Totally NOT prototypical.
Maybe a push pull 3 way valve that allows both side tanks & trolley to feed the injectors depending on whether it’s pushed or pulled?

Cheers Kerrin

[Roger]

Dec 1, 2018 1:27:41 GMT David said:

Very nice. 1 & 2mm cutters in silver steel? What spindle speed and feed rate was that?

Hi David,
The 2mm cutter was using 10mm/min and about 2000RPM with a 0.5mm deep cut. The 1mm was 5mm/min and only 0.25mm and a bit faster RPM. The 3D entry was set to 2 degrees. If the cutter breaks, go less deep and go slower. There's no magic to cutting anything, just be more gentle if cutters start to suffer or they break. There are no fixed feeds and speeds for anything, it all depends on the particular job. In this case, it gives the cutters an easier time if you drill the corners first so the 1mm cutter doesn't have to dive into them when you switch from 2mm to 1mm diameter.

[Roger]

Dec 1, 2018 6:31:50 GMT steamer5 said:

Hi Rodger,
Spent many happy hours driving a Speedy that used to visit my home track. Never had a issue with the water getting to warm, water on at the beginning of the day, top up tanks as required, water dribbling out the injector when not running, worked great!
As an aside, this Speedy had quite a few mods to the LBSC drawings......too long ago to remember what, but the one that does stick is sight glasses on the side tanks visible in the cab! Totally NOT prototypical.
Maybe a push pull 3 way valve that allows both side tanks & trolley to feed the injectors depending on whether it’s pushed or pulled?

Cheers Kerrin

Hi Kerrin,
That's good to know. The SPEEDY plans show a flat back to the side tanks, so that must give a generous amount of insulation. I presume that's why you didn't have any problems, as well as letting the injectors dribble.
I'm certainly interested in making some kind of arrangement for showing the water level.
Yes, a 3 way valve operated from the cab looks like the favourite, but I plan to fill the side tanks using that water so there's a constant supply of cool water to them.

[terrier060]

Also useful to make sure the end of the bypass pipe is close to the tank filler so that you can check that the axle pumps are working OK. Two pumps are better than one in my opinion as they give smoother action.

[Roger]

Dec 1, 2018 11:55:56 GMT terrier060 said:

Also useful to make sure the end of the bypass pipe is close to the tank filler so that you can check that the axle pumps are working OK. Two pumps are better than one in my opinion as they give smoother action.

Hi Ed,
I've seen this mentioned but I've never driven a locomotive laid out like that. I guess it's useful, but you can hear it creaking if it's delivering water to the boiler. The more pronounced the creaking, the more is being delivered. I guess you would open the tank cover to see the return?

I'm not sure returning the water into one tank is a good idea since the levels will only be restored by the balance pipe.

Another consideration is where to put the bypass valve. Running pipes back and forth past the firebox seems less desirable than running a rod to operate a valve remotely where it's needed. I'm inclined to put the bypass valve near the pump and feed the bypass straight back into the balance tube. The shorter the pipe, the easier it is to plumb, the less the losses and the less heat it can absorb.

Agreed that two pumps are probably better than one, although I've not really noticed pumps causing uneven running. I've reduced the size on mine to 10mm diameter so it's not that big really. Most of the time I won't use it, the intention is to use the injectors and use the pump to draw water from the riding truck tank if there is one.

[Deleted]

Dec 1, 2018 11:55:56 GMT terrier060 said:

Also useful to make sure the end of the bypass pipe is close to the tank filler so that you can check that the axle pumps are working OK. Two pumps are better than one in my opinion as they give smoother action.

I was told this when building 4470, I can't remember if it was from this forum or in LBSC's notes? 4470 being a tender loco, the return pipe ends just under the filler lid so you just need to open the lid to see if the pump is working or not.

Pete

[chris vine]

Yes, certainly you should run the bypass pipe back into one of the tanks. It doesn't matter if it gets balanced back to the other one.

If you put the pipe so you can see it when you open a filler then you can see what is happening...

Chris.

[stevep]

The bypass of the crosshead pump on my ROB ROY discharges just under one of the filler caps, and I always remove the cap when running so I can see the flow. Not to make sure that the pump is working, but so I can gauge how much water I am putting into the boiler.

I remember that LBSC said that if you adjusted the bypass correctly, you could carry on running without having to touch the bypass. It's not just for a 'top up', but correctly adjusted, maintains the level of water in the boiler whilst running.

I turn mine down a bit (i.e. open the bypass) when notched up, and increase the supply to the boiler when I move towards full gear.

[Roger]

I'm not convinced of the value of being able to see the water returning into the side tank. You can hear when it's working, so why do you need to check that visually? You've got the water gauge to see how much water there is in the boiler so you can see what effect it's having. Maybe on small locomotives it's more useful? I've run locomotives with just an axle pump and haven't had any difficulty in knowing what's going on.

To my way of thinking, it just complicates the plumbing unnecessarily. If the bypass valve is operated remotely by rod that goes along the side of the firebox, you can have a really neat circuit that comes out of the balance pipe, through the pump and then back into the balance pipe after the bypass valve.


I've decided to bite the bullet and add all of the missing holes to the frames and paint it properly.

This is my monster parallel being used to set up some back stops which will make setting the frames parallel to the top easier. I'm clocking the back of the parallel and holding the stops against it, lightly nipped up until it's true.


20181201_114739 by Roger Froud, on Flickr

The original paint wasn't heat resistant enough and too easily scratched. Interestingly, the grey primer is really on there, that's going to take a lot of getting off.

20181201_214633 by Roger Froud, on Flickr

[delaplume]

Dec 1, 2018 23:36:18 GMT Roger said:

I'm not convinced of the value of being able to see the water returning into the side tank. You can hear when it's working, so why do you need to check that visually? You've got the water gauge to see how much water there is in the boiler so you can see what effect it's having. Maybe on small locomotives it's more useful? I've run locomotives with just an axle pump and haven't had any difficulty in knowing what's going on.

To my way of thinking, it just complicates the plumbing unnecessarily. If the bypass valve is operated remotely by rod that goes along the side of the firebox, you can have a really neat circuit that comes out of the balance pipe, through the pump and then back into the balance pipe after the bypass valve.


I've decided to bite the bullet and add all of the missing holes to the frames and paint it properly.

This is my monster parallel being used to set up some back stops which will make setting the frames parallel to the top easier. I'm clocking the back of the parallel and holding the stops against it, lightly nipped up until it's true.


20181201_114739 by Roger Froud, on Flickr

The original paint wasn't heat resistant enough and too easily scratched. Interestingly, the grey primer is really on there, that's going to take a lot of getting off.

20181201_214633 by Roger Froud, on Flickr

Hi Roger,

Personally I use a dropping pressure gauge to tell me in the first instance......Feedwater entering a boiler will always condense and reduce the pressure, even when working hard and in full gear........You shouldn't really be driving with the safety blowing off ( Poor firing technique  ) so you can't rely on hearing the safety shut off.........and the gauge glass level never stays still long enough to get a comparative reading eg}----going up or down gradients etc..

Also long or big capacity boilers will be slow to react to changes in level and that's also assuming that you have done your gauge glass blowdown procedure prior to taking a reading and that the gaugeglass is reading correctly anyway.....

Here is a 57xx pannier tank --- they have a short rod going from the cab to the water valve which is bolted directly to the underside of each water tank.....An 8x injector is plumbed directly into that to form a neat but a sodoffa job to work on...........Just a thought re}---- a bypass system in general..It only requires a partial blockage in the return line to the water tank for the system to be permanently inserting water that's beyond your control.....

[steamer5]

Hi Rodger,
For what’s its worth, my Dad has returns visible thru the hatches on his side tanks, he has an NZR WW in 5”, he wouldn’t be without them. It shows that the axel pumps are running well & what’s going thru the bypass. Oh on the balance line go as big as you can..... 1/2” would be a minimum....... Dad had rubber tubing between them.....don’t use it! It gets oil on it & goes hard & fails use silicon problem solved! It’s inevitable that filling of the tanks will be from one side so big is better!
Even if you go the route of not wanting pipeing for I would suggest that you put them in when building your tanks, way easier now than trying to fit them latter!

Cheers Kerrin

[Roger]

Dec 2, 2018 5:07:44 GMT delaplume said:

Dec 1, 2018 23:36:18 GMT Roger said:

Hi Roger,

Personally I use a dropping pressure gauge to tell me in the first instance......Feedwater entering a boiler will always condense and reduce the pressure, even when working hard and in full gear........You shouldn't really be driving with the safety blowing off ( Poor firing technique  ) so you can't rely on hearing the safety shut off.........and the gauge glass level never stays still long enough to get a comparative reading eg}----going up or down gradients etc..

Also long or big capacity boilers will be slow to react to changes in level and that's also assuming that you have done your gauge glass blowdown procedure prior to taking a reading and that the gaugeglass is reading correctly anyway.....

Here is a 57xx pannier tank --- they have a short rod going from the cab to the water valve which is bolted directly to the underside of each water tank.....An 8x injector is plumbed directly into that to form a neat but a sodoffa job to work on...........Just a thought re}---- a bypass system in general..It only requires a partial blockage in the return line to the water tank for the system to be permanently inserting water that's beyond your control.....

Hi Alan,
The arrangement on 3650 looks the same as mine. I can use a similar rod on the other side for the bypass valve control, although it will require a little ingenuity to connect it to the valve itself.
I don't think there will be any issues with blockages causing problems, the pipe will be big enough to allow small particles to pass. The aim is to keep those out with filters in the tanks.

[Roger]

Dec 2, 2018 5:26:22 GMT steamer5 said:

Hi Rodger,
For what’s its worth, my Dad has returns visible thru the hatches on his side tanks, he has an NZR WW in 5”, he wouldn’t be without them. It shows that the axel pumps are running well & what’s going thru the bypass. Oh on the balance line go as big as you can..... 1/2” would be a minimum....... Dad had rubber tubing between them.....don’t use it! It gets oil on it & goes hard & fails use silicon problem solved! It’s inevitable that filling of the tanks will be from one side so big is better!
Even if you go the route of not wanting pipeing for I would suggest that you put them in when building your tanks, way easier now than trying to fit them latter!

Cheers Kerrin

Hi Kerrin,
I'll show the balance pipe shortly. I've gone for a semi-prototypical rectangular one which is over size to get enough cross section. It will be of the same order of size as what you suggest.

I just can't see me opening the fillers to view the bypass return on the run. It's obvious when it's pumping, you can hear it, and the water level goes up. I wonder if it's done for reassurance because a sticking inlet valve is a common problem and you can check it's pumping when the bypass valve is open? Mine can't stick, so that's not going to be an issue.

[chris vine]

Hi Roger,

On my small tank loco, with axle pump, I only check that the pump is working (including that the pipe feeding it with strainer gauze) while raising steam. Then if it were not to work (it never hasn't), I can sort it out before being in steam.

I cannot hear my pump working by the way.

You don't need to run the pipe up the outside of the tank of course. it can go up the inside.

However, you seem to not want to do that and it is very unlikely that you will have a problem. Don't forget that if you ever did run short of water, you can put a rag in the chimney and turn on the blower so that steam goes back through the boiler and into the firebox. It will cool the fire and exclude air so it will go out pretty quickly. Maybe you can drop the grate in your design, I cannot remember.

I like the comment about setting the bypass so that it always feeds correctly for the loco. This only works if you tend to drive at the same speed. Imagine you set the bypass valve only open slightly: At slow speed, most of the water pumped will be able to squeeze through the opening in the valve, while at high speeds, the water cannot get through fast enough. The pump (give or take a bit) will pump at a rate proportional to speed.

I had this proved when I took the little loco to a very long circular track which invited fast running!

Chris.

[Roger]

Dec 2, 2018 10:32:03 GMT chris vine said:

Hi Roger,

On my small tank loco, with axle pump, I only check that the pump is working (including that the pipe feeding it with strainer gauze) while raising steam. Then if it were not to work (it never hasn't), I can sort it out before being in steam.

I cannot hear my pump working by the way.

You don't need to run the pipe up the outside of the tank of course. it can go up the inside.

However, you seem to not want to do that and it is very unlikely that you will have a problem. Don't forget that if you ever did run short of water, you can put a rag in the chimney and turn on the blower so that steam goes back through the boiler and into the firebox. It will cool the fire and exclude air so it will go out pretty quickly. Maybe you can drop the grate in your design, I cannot remember.

I like the comment about setting the bypass so that it always feeds correctly for the loco. This only works if you tend to drive at the same speed. Imagine you set the bypass valve only open slightly: At slow speed, most of the water pumped will be able to squeeze through the opening in the valve, while at high speeds, the water cannot get through fast enough. The pump (give or take a bit) will pump at a rate proportional to speed.

I had this proved when I took the little loco to a very long circular track which invited fast running!

Chris.

Hi Chris,
I can certainly see why you might want to check the pump is working if that's the primary source of boiler feed water. Designing the inlet valve so it can't get stuck on the seat ought to remove any doubts about whether it will work or not. It's so simple that it's hard to imagine that it won't.

The tip for putting out the fire is a good one, I've never tried it, but it's handy to have in the back of your mind in case of emergency. I can drop the grate too, but I like the idea of extinguishing it in situ.

I've used a partially closed bypass quite a few times and adjusted it slightly over time. It's lazy, but it works. I dread to think how poor the efficiency of doing this is, especially if the pump delivery is a lot more than required for the running you're doing. Still, it's fun to have all the options and to play with these things.

[pault]

Personally I dislike pumps for a number of reasons. Two injectors is all that is fitted to the vast majority of the Cockcrow loco, and a significant number of locos there have had their pumps removed. Something that may not be obvious is that should the clack, that the pump feeds through, be leaking or stick up you will get an intermittent steam/hot water feed into the tank which can quite quickly heat up the water in the tank. This is not always immediately obvious that this is happening.

On a 7 ¼” tender loco it can be quite nice to have a warm tender to sit on, during a winters day run. The down side is your injectors will not be so happy at the hot water.