don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 961 
|
Post by don9f on Nov 5, 2019 23:35:28 GMT
Hi, whether piano wire or stainless wire, 18swg is pretty stiff and in my opinion is a bit on the big side for the drain cocks. Can you try something a bit smaller and see if that helps? My Jinty uses a similar arrangement....I know it’s smaller etc. but it works a treat with a 3/32” copper tube and I’ll have to check the wire, but it’s much smaller than 18swg (.048”), probably 22swg (.028”).
Cheers Don
|
|
|
|
Post by ettingtonliam on Nov 6, 2019 2:26:13 GMT
When I built 'Juliet' many many years ago, I used bowden cable (bicycle brake cable) in copper tube, and that worked without excessive effort. I imagine that was LBSC's suggested method as in those days, I worked pretty closely to the 'Words and Music'
|
|
|
|
Post by runner42 on Nov 6, 2019 6:35:47 GMT
Thanks for the replies. Is piano wire better than stainless? I rather glossed over the fact that DY specified piano wire, I used stainless because it was readily available. Because there is some doubt that I have used non specified wire I have not finalised the assembly, allowing the easy substitution of piano wire without major disassembly. I may have been premature in decrying Don's design because of the wire issue. At least I am happy that I have redesigned the mounting of the cab operated lever from cab side to chassis. This is the LHS assembly I fabricated from steel sheet and silver soldered together  Lever assembly LHS by Brian Leach, on Flickr and RHS,  Lever assembly RHS by Brian Leach, on Flickr Assembly on the chassis  Lever assembly on chassis1 by Brian Leach, on Flickr  Lever assembly on chassis2 by Brian Leach, on Flickr To address some specifics mentioned in the replies, I agree that a large spring on the drain cock end to assist in the push part of operation is a good suggestion and I shall considered implementing that if needed. The size of the wire may be an issue but unless and until I have obtained piano wire of the specified gauge I don't know if a smaller gauge may improve the situation. An issue that may affect what I have already done is can piano wire be silver soldered? Pete I shall be happy to receive Don's push pull system on Doncaster. Brian |
|
|
|
Post by Deleted on Nov 6, 2019 9:51:33 GMT
Hi Brian yes to piano wire over stainless, piano wire has a memory, ie it will spring back when coiled, also it's very tough, resistant to kinks. My Lassie has followed LBSC words and is a length of piano wire in copper tube, works well, not that I've used it much..  Here's Don drawing for the 'push-pull' Bowden cable system...  Kind regards Pete |
|
|
|
Post by ettingtonliam on Nov 6, 2019 10:02:19 GMT
Thats a bit of a contradiction isn't it? He says bowden cable to start with, then says 22G or 24G piano wire. They are not the same thing.
|
|
don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 961
|
Post by don9f on Nov 6, 2019 10:04:32 GMT
Yes, piano wire can be soft soldered easily.
The wire in my 3/32” tube is actually 0.8mm (.031”)....retrieved from an old defunct model aircraft.
Cheers Don
|
|
|
|
Post by Deleted on Nov 6, 2019 10:31:13 GMT
Thats a bit of a contradiction isn't it? He says bowden cable to start with, then says 22G or 24G piano wire. They are not the same thing. Ah...very true...guess I dismissed that as already decided to do the typical Bowden cable push-pull which I have used many times before being my preferred method. I had forgotten that I was going my own way here, I did post pictures of the tube and cable that I plan to use in my thread... Sorry chaps...my mind goes a bit astray sometimes... Pete |
|
|
|
Post by Roger on Nov 6, 2019 12:04:13 GMT
You might consider looking at some of the offerings to the Model Aircraft hobby. I think they have ones with PTFE or low friction linings which might solve the problem.
|
|
|
|
Post by Deleted on Nov 6, 2019 12:16:36 GMT
You might consider looking at some of the offerings to the Model Aircraft hobby. I think they have ones with PTFE or low friction linings which might solve the problem. Hi Roger I have a fair bit of experience with R/C aircraft flight control systems plus many years on Amnimatronics in film/TV...I had thought of this but decided against due to the close proximity to heat...I think the cable will jam as the PTFE gets hot...my chosen material is copper outer, I bought some small bore refrigerater copper tube. Give me a few years and I'll report back whether it works or not... Pete |
|
|
|
Post by gwr14xx on Nov 6, 2019 13:06:21 GMT
Pete, Another option might be the liner tube from a MIG welder cable (the one that guides the filler wire).
Eddie.
|
|
|
|
Post by Deleted on Nov 6, 2019 13:48:10 GMT
Pete, Another option might be the liner tube from a MIG welder cable (the one that guides the filler wire). Eddie. Now that sounds like a great idea Eddie... worth experimenting with...next time I'm at my son's I'll see if he has any lying around..... cheers Pete |
|
|
|
Post by runner42 on Nov 8, 2019 7:33:25 GMT
I looked at the three WIP builds for a master class on constructing the petticoat pipe. Roger opted for spinning a copper tube, but because it was thin walled tube to enabled spinning to occur he had to make jigs and fixtures to hold the copper tube in the 3 jaw chuck. I don't know what the speed of the lathe must reach to enable spinning to occur I feel mine is too slow. Roger's Speedy petticoat pipe appears a rather short bell mouth compared to mine. Pete uses a casting which greatly simplifies the task although machining the curve has its challenges. An aside Photobucket has added a watermark, but worst still has de-focused the photo to be worse than my poorest photo. Steve is yet to post his. So I don't think I can copy any of the aforementioned. I have decided to follow my normal procedure and fabricate the petticoat pipe. Firstly a drawing of what's required.  petticoat pipe by Brian Leach, on Flickr The solution is a two gunmetal annulus construction shown in black, silver soldered together and then machined to provide the curves shown in red. This will be mated non permanently with the chimney and the two degree taper machined.  petticoat pipe construction by Brian Leach, on Flickr But I am open to suggestions if another method is proposed. Brian |
|
mbrown
Elder Statesman
Posts: 1,796
|
Post by mbrown on Nov 8, 2019 8:09:13 GMT
I used the same approach you propose. But I took the lower part up to the level of the flange which attaches to the smoke box and profiled it to the inside radius of the smoke box before soldering the two bits together. I didn't bother profiling the outside, just the bell mouth and taper. There's no great merit in what I did but it does save having to solder on a separate flange made of sheet, and I found it easier to profile the bigger lump of brass than trying to bend a flange from sheet.
Just a thought.
Malcolm
|
|
|
|
Post by gwr14xx on Nov 8, 2019 8:12:03 GMT
Brian,
I normally form this type of bellmouth from copper tube. Firstly, turn up a couple of plugs from offcuts of mild steel - one with the 2 degree taper, and another with the flare of the petticoat pipe - then polish the surfaces. Acquire a suitable piece of copper tube and square up the ends to the required length, and anneal it. When it has cooled, smear a light coating of thick grease on the bore (I use water pump grease) and on the outside of the 2 plugs. Enter the 2 plugs in the ends of the tube and squeeze the assembly in the vice (with a plate to prevent the taper plug from going too far into the tube - as this end will form more easily). It is surprising how much flare you can achieve with just the one pressing - if need be, re-anneal and repeat the operation.
Regards,
Eddie
|
|
|
|
Post by Roger on Nov 8, 2019 14:51:00 GMT
I looked at the three WIP builds for a master class on constructing the petticoat pipe. Roger opted for spinning a copper tube, but because it was thin walled tube to enabled spinning to occur he had to make jigs and fixtures to hold the copper tube in the 3 jaw chuck. I don't know what the speed of the lathe must reach to enable spinning to occur I feel mine is too slow. Roger's Speedy petticoat pipe appears a rather short bell mouth compared to mine. Pete uses a casting which greatly simplifies the task although machining the curve has its challenges. An aside Photobucket has added a watermark, but worst still has de-focused the photo to be worse than my poorest photo. Steve is yet to post his. So I don't think I can copy any of the aforementioned. I have decided to follow my normal procedure and fabricate the petticoat pipe. Firstly a drawing of what's required. petticoat pipe by Brian Leach, on Flickr The solution is a two gunmetal annulus construction shown in black, silver soldered together and then machined to provide the curves shown in red. This will be mated non permanently with the chimney and the two degree taper machined. petticoat pipe construction by Brian Leach, on Flickr But I am open to suggestions if another method is proposed. Brian Hi Brian, Although I did spin a tube, that's not what I ended up using. I 3D machined one from a solid piece of Mild Steel Bar in the end. Spinning can be done at any speed you like, it only affects the rate at which it can be done. You'd easily be able to spin something that's only flared slightly like yours is. The key is in trapping the tube between an inside support and an outside split ring. A smooth surface on the tool you're working the metal will is a big help as is some sort of lubricant. You can anneal it as many times as you like if it's Copper or Brass to get the desired shape. It's a lot easier than you might imagine. |
|
|
|
Post by runner42 on Nov 8, 2019 22:05:17 GMT
Hi Roger,
using mild steel, how did you prevent rusting given the environment in which it resides?
Brian
|
|
|
|
Post by Roger on Nov 9, 2019 9:02:07 GMT
Hi Roger, using mild steel, how did you prevent rusting given the environment in which it resides? Brian Hi Brian, I intend to paint it with the same paint used on the smokebox, but another alternative would be to Nickel plate it. I don't know how serious a problem rust is inside the smokebox to be honest, I thought it would very soon end up covered in black sooty deposits. Perhaps someone has some experience as to whether that helps or makes rusting worse. |
|
|
|
Post by doubletop on Nov 10, 2019 9:20:19 GMT
|
|
|
|
Post by doubletop on Nov 10, 2019 9:41:56 GMT
I looked at the three WIP builds for a master class on constructing the petticoat pipe. Roger opted for spinning a copper tube, but because it was thin walled tube to enabled spinning to occur he had to make jigs and fixtures to hold the copper tube in the 3 jaw chuck. I don't know what the speed of the lathe must reach to enable spinning to occur I feel mine is too slow. Roger's Speedy petticoat pipe appears a rather short bell mouth compared to mine. Pete uses a casting which greatly simplifies the task although machining the curve has its challenges. An aside Photobucket has added a watermark, but worst still has de-focused the photo to be worse than my poorest photo. Steve is yet to post his. So I don't think I can copy any of the aforementioned. I have decided to follow my normal procedure and fabricate the petticoat pipe. Firstly a drawing of what's required. petticoat pipe by Brian Leach, on Flickr The solution is a two gunmetal annulus construction shown in black, silver soldered together and then machined to provide the curves shown in red. This will be mated non permanently with the chimney and the two degree taper machined. petticoat pipe construction by Brian Leach, on Flickr But I am open to suggestions if another method is proposed. Brian Hi Brian, Although I did spin a tube, that's not what I ended up using. I 3D machined one from a solid piece of Mild Steel Bar in the end. Spinning can be done at any speed you like, it only affects the rate at which it can be done. You'd easily be able to spin something that's only flared slightly like yours is. The key is in trapping the tube between an inside support and an outside split ring. A smooth surface on the tool you're working the metal will is a big help as is some sort of lubricant. You can anneal it as many times as you like if it's Copper or Brass to get the desired shape. It's a lot easier than you might imagine. I tried spinning a bit of copper tube and gave up. I did these for my Rob Roy by turning up the blank to the outer dimensions. Then holding in the chuck with the end petticoat outwards. Bore to the smallest diameter. Set the tool post to 2deg and bore the taper. Then set the tool post to 2 deg the other direction and bore a taper to the petticoat, then 4 deg, 6 deg, 8deg 10 deg etc. So you get a rough petticoat shape with can then be finished by hand with emery paper. The one on the left is the one I was replacing as it was just a bit of flared brass tube. The one on the right was my first attempt. The second one I did ended uo with a better flare than the one in the photo. I don't have a picture of that I'm afraid   It was pretty easy really and quick Pete |
|
|
|
Post by runner42 on Nov 15, 2019 7:23:03 GMT
Received the two gunmetal blanks that will be used to fabricate the petticoat pipe. This is a costly method of fabricating the petticoat pipe, the larger one costs $32 and the smaller one cost $15. The quoted length of each is 25 mm, which combined is a smidgen too short, but as expected the delivered length was 26 mm, so I had enough metal to meet the length measurement.  two GM blanks by Brian Leach, on Flickr I bored a 1" hole in each and silver soldered them together. In retrospect I should have taken more metal off before silver soldering because it took a while to heat the pieces to enable the silver solder to flow.  two GM blanks silver soldered by Brian Leach, on Flickr I used a number of methods to to get the shape required the outside profile was not as important, so I gave little attention to it. However I made a gauge for the inner profile and spent some time getting it right. I mated the petticoat pipe to the chimney using loctite for the purposes of boring the 2 deg reverse taper.  petticoat pipe mated to chimney by Brian Leach, on Flickr I used the compound slide to achieve the 2 deg reverse taper, however the compound slide travel is a bit under 2 1/2" and I needed a good 3". I frigged it, so I won't go into detail just in case I get some brickbats. However I don't think the steam will have too many problems in transitioning through.  boring 2 deg taper by Brian Leach, on Flickr Brian |
|
