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Post by andyhigham on Nov 4, 2018 21:00:09 GMT
I once welded an ashpan together from 1.5mm steel sheet using a stick welder... needless to say the job was not as neat as yours Roger, looking good! I gas welded the stainless steel ashpan for my Sweet Pea, what a ba$t4rd of a job that was |
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Post by Roger on Nov 4, 2018 22:41:28 GMT
It all seems to fit ok, so it's time to weld it up properly...  20181104_083941 by Roger Froud, on Flickr ... which pulled the sides in a bit. Here I'm using a piece from the mill clamping set and an M12 bolt to stretch it.  20181104_210700 by Roger Froud, on Flickr Doing the welding in short sections and moving from place to place helps to stop it distorting too much...  20181104_211219 by Roger Froud, on Flickr ... but I should have put a piece of metal on the back to take the heat away here because it's got too hot on the back of the weld.  20181104_211441 by Roger Froud, on Flickr It's cleaned up ok, but really it wants an abrasive pad on the angle grinder or a very fine wheel to take off the lumpy bits.  20181104_222947 by Roger Froud, on Flickr It certainly won't win any prizes in a welding competition, but it's mighty strong!  20181104_223006 by Roger Froud, on Flickr |
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Post by Jim Scott on Nov 5, 2018 21:51:40 GMT
Hi Roger
If anyone doubts the usefulness of the TIG welding process let them consider how they would make up this ashpan otherwise. Maybe it is possible to do an Origami job, or simple folds silver-soldered, or even flanged and riveted, but none would be as elegant a solution as that you have chosen. Excellent work...
I think there is a general perception that TIG welding is a bit esoteric, but in fact it is considerably easier than oxy-acetylene, manual metal arc (MMA - 'stick' welding) or metal-inert gas (MIG) welding for delicate parts. You do need a steady hand and the ability to hand feed a filler wire (same as gas welding), but given this it is in a class of its own.
You mentioned melting through the joint in places and possible use of metal heatsinks. Copper is often used as a backing material, principally because it conducts the heat away rapidly and it won't easily melt into your weld pool. Close fitting backings also control any burn through as well as hindering free atmospheric access to the back of the weld, leaving a cleaner appearance.
Welding short sections is very useful method of controlling distortion. Also, if your inverter has the facility for pulse welding do try it. A series of overlapping spots can allow a continuous weld at a lower total heat input which means less distortion. Same idea as the 'jewelry' spot welders mentioned some months ago but with the arc swapping continuously between a high and very low power setting.
Good to see your continuing progress with Speedy, wish I could manage half as much..!
Jim S
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Post by Roger on Nov 5, 2018 22:30:00 GMT
Hi Roger If anyone doubts the usefulness of the TIG welding process let them consider how they would make up this ashpan otherwise. Maybe it is possible to do an Origami job, or simple folds silver-soldered, or even flanged and riveted, but none would be as elegant a solution as that you have chosen. Excellent work... I think there is a general perception that TIG welding is a bit esoteric, but in fact it is considerably easier than oxy-acetylene, manual metal arc (MMA - 'stick' welding) or metal-inert gas (MIG) welding for delicate parts. You do need a steady hand and the ability to hand feed a filler wire (same as gas welding), but given this it is in a class of its own. You mentioned melting through the joint in places and possible use of metal heatsinks. Copper is often used as a backing material, principally because it conducts the heat away rapidly and it won't easily melt into your weld pool. Close fitting backings also control any burn through as well as hindering free atmospheric access to the back of the weld, leaving a cleaner appearance. Welding short sections is very useful method of controlling distortion. Also, if your inverter has the facility for pulse welding do try it. A series of overlapping spots can allow a continuous weld at a lower total heat input which means less distortion. Same idea as the 'jewelry' spot welders mentioned some months ago but with the arc swapping continuously between a high and very low power setting. Good to see your continuing progress with Speedy, wish I could manage half as much..! Jim S Hi Jim, You've highlighted just about everything anyone needs to know about TIG welding, and I agree that it's not very difficult to learn. My welder was bought specifically to have the capability for welding 0.7mm thick Superheater tubes, and it has a completely programmable set of presets. I've been using Steel bar on the back of the last weld and that worked very well. |
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Post by Roger on Nov 5, 2018 22:36:31 GMT
I found some carborundum discs in the loft while clearing some space, and I've put those to good use in tidying up the welds on the outside.  20181105_170218 by Roger Froud, on Flickr I was a bit concerned that those open slots in the front and back might let ash escape over the working parts of the chassis. I've added a sloping extension to the bottom of the slot and this is one of the sides being filled in.  20181105_203011 by Roger Froud, on Flickr  20181105_203423 by Roger Froud, on Flickr I like this much better, there's plenty of area for air to get in, but any ash ought to have a better chance of being caught.  20181105_210608 by Roger Froud, on Flickr  20181105_210638 by Roger Froud, on Flickr This is the start of the same arrangement at the back. I'll put sides on this too.  20181105_222216 by Roger Froud, on Flickr |
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Post by Roger on Nov 6, 2018 22:33:48 GMT
I've added the triangular infills on the front opening this evening. It all looks a bit rough in this shot, the light is being a bit unkind.  20181106_210300 by Roger Froud, on Flickr Yesterday I ran the program again that ended up damaging the vice. This time I ran it in fresh air and without backlash compensation since I'm only making a grate and it doesn't need that last bit of accuracy. The counts came back to the micron, so today I've started on the second attempt at making the Rosebud grate. It's really tough Stainless Steel plate, and the drill needed sharpening 5 times to get all of these holes done. I used the quill fed by hand on this, I wouldn't trust it on CNC without flood coolant, and even then I would probably stand over it.  20181106_105111 by Roger Froud, on Flickr The idea of drilling the holes first was to give the milling cutter an easier time on the entry for each cut. The finish is terrible, but this is just the first coarse roughing cut to remove the bulk of the unwanted material.  20181106_160438 by Roger Froud, on Flickr I took this pretty gently, with a feedrate of 40mm/min and it took a total of 10-1/2 hours to complete. I hoovered up a couple of times and covered it generously with cutting oil each time, but other than that I let it do its own thing.  20181106_211123 by Roger Froud, on Flickr You may be wondering why I didn't just use a centre drill for these, it's exactly the right size and angle. If you've ever tried going really deep with a centre drill, you'll know that the very long cutting edge can cause problems. On a very rigid industrial machine, with flood coolant and a Carbide centre drill, you could probably get away with it, but I could forsee this just generating huge amounts of heat and wrecking the tool. Add to that the fact I'd have had to stand here and do them all and I thought it was just easier to 3D machine them and accept the fact that it's going to take twenty or more hours to complete. |
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Post by Roger on Nov 7, 2018 21:49:25 GMT
This is how it looked after a 4 hour finishing pass with 0.25mm stepover. It's not bad, but I decided to do a second pass at 90 degrees to tidy up the slopes in the other direction that were more like steps.  20181107_204516 by Roger Froud, on Flickr  20181107_222050 by Roger Froud, on Flickr The result is this.... not amazing, but good enough. I could have gone with a finer pass in both directions but it will do.  20181107_204527 by Roger Froud, on Flickr Looking at the space where the grate fits, I can see a big problem with tipping the grate up. I don't want to drop the grate, I want it to stay hinged on the ashpan. The narrow ashpan section above the axle means that it has to hinge roughly in the middle, and that means the back end of the grate needs to swing up into the firebox, at least enough to rake the contents of the fire out at the front. That's not going to happen with the grate shown below, because it's going to hit the stays, even though I've trimmed them back a bit.  Rosebud grate by Roger Froud, on Flickr The solution I've settled on is to make the grate as narrow as that part on the above model where it fits inside of the flanged end plates. Obviously that would leave a big gap around the edge of the grate, so I'll fill that gap with a couple of strips of Copper sheet. That way I can swing the back of the grate up and it can use the longer stays as a stop so it doesn't tip up too far. Ok, I'm losing a little bit of grate area, but I'm sure I've got more than enough with that small bit missing.  Revised narrow grate by Roger Froud, on Flickr |
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Post by chris vine on Nov 7, 2018 22:42:12 GMT
Roger,
On emptying ash out of fireboxes:
On my little tank engine, which has a tipping grate and hopper door in the ashpan, I always use that and drop the ash etc onto the track. However, it makes a terrible mess of all the motionwork between the frames as the ash is very fine and blows (rises with hot air) and gets everywhere.
With Bongo, which I also made with a proper tipping grate and mechanism, I never use it. I don't want to get everything filthy as I took a lot of time to make it nicely. So with Bongo, I always hoover out the firebox with the workshop vacuum and a bit of flexible/shaped hose which fits in through the firehole door. Any ash which gets disturbed goes straight up the pipe anyway.
To empty the ashpan, I suck that out too as it doesn't have a trap door at the bottom, only the air inlet at the front (as per full size). However, even if the ashpan did have a drop door at the bottom, I would still have the vacuum pipe beside it so that all the dust which floats about would go up the pipe.
Your loco is so detailed that you will be very upset when all your work gets coated in ash, stuck to oil!!
What is amazing is that the LNER B1 was designed during WW2, but they still didn't (at least on the first batch) bother with making an ashpan (hopper type) with a drop door at the bottom. The shed men had to rake out the ash, while standing in the ash pit. What an awful job and one which could so simply have been fixed with a little thought at the design stage.
For the later batches of B1s they did fit hopper ashpans. I guess that after the war, there simply wasn't enough manpower (or wages had gone up) to waste on raking out ashpans.
Chris.
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Post by Roger on Nov 7, 2018 23:17:37 GMT
Roger, On emptying ash out of fireboxes: On my little tank engine, which has a tipping grate and hopper door in the ashpan, I always use that and drop the ash etc onto the track. However, it makes a terrible mess of all the motionwork between the frames as the ash is very fine and blows (rises with hot air) and gets everywhere. With Bongo, which I also made with a proper tipping grate and mechanism, I never use it. I don't want to get everything filthy as I took a lot of time to make it nicely. So with Bongo, I always hoover out the firebox with the workshop vacuum and a bit of flexible/shaped hose which fits in through the firehole door. Any ash which gets disturbed goes straight up the pipe anyway. To empty the ashpan, I suck that out too as it doesn't have a trap door at the bottom, only the air inlet at the front (as per full size). However, even if the ashpan did have a drop door at the bottom, I would still have the vacuum pipe beside it so that all the dust which floats about would go up the pipe. Your loco is so detailed that you will be very upset when all your work gets coated in ash, stuck to oil!! What is amazing is that the LNER B1 was designed during WW2, but they still didn't (at least on the first batch) bother with making an ashpan (hopper type) with a drop door at the bottom. The shed men had to rake out the ash, while standing in the ash pit. What an awful job and one which could so simply have been fixed with a little thought at the design stage. For the later batches of B1s they did fit hopper ashpans. I guess that after the war, there simply wasn't enough manpower (or wages had gone up) to waste on raking out ashpans. Chris. Hi Chris, That's very interesting and useful, as always! I do like the idea of being able to easily take out the grate, and the way I have it arranged, it's just a matter of releasing the front pin with the lever in the cab. The back of the grate can then be raised to release it from the inverted 'U' shaped pivot and then slide it out. It does need to be at quite a steep angle to do that, so I think the method of letting the grate go up inside the firebox inside of the stays makes sense. I hear what you say about the mess though, I can see why you hoover it out. The downside is that the fire has to go completely out, so a quick exit from the track isn't as easy. I'm fortunate in not having motion inside, but there are the eccentrics for the pump and lubricator, and I'd like to keep them free from ash if possible. So it looks like the best strategy is to leave it to go cold and deal with the ash later. When we run at the fetes, we just drop the grate, but then we don't have bottoms to the ash pan, and there isn't much ash to get rid of. |
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Post by 92220 on Nov 8, 2018 9:06:34 GMT
Hi Roger.
The hot ash may not be such a problem if you get hold of a vacuum that will handle hot ash. Available from Groupon:- Pifco Electric 18-Litre Hot Ash Vacuum Cleaner 1200W
£28.73 plus £1.99 shipping.
Bob.
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Post by Roger on Nov 8, 2018 9:31:49 GMT
Hi Roger. The hot ash may not be such a problem if you get hold of a vacuum that will handle hot ash. Available from Groupon:- Pifco Electric 18-Litre Hot Ash Vacuum Cleaner 1200W £28.73 plus £1.99 shipping. Bob. Hi Bob, Well, I had no idea that such a thing existed. A quick search of eBay shows many different ones. I'll certainly consider getting one of those. |
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Post by 92220 on Nov 8, 2018 16:58:03 GMT
Hi Roger.
I think they work a bit like the vacuums that will suck up water. They don't have a filter but separate the dust and solids by a high speed spin and centrifugal action.
Bob.
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,990
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Post by JonL on Nov 8, 2018 18:05:38 GMT
I really love the idea of a Rosebud grate. Whether I love the idea enough to risk it on my first locomotive I don't yet know... I wonder if its been done on a Britannia. To Google!
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Post by Roger on Nov 8, 2018 18:17:41 GMT
I really love the idea of a Rosebud grate. Whether I love the idea enough to risk it on my first locomotive I don't yet know... I wonder if its been done on a Britannia. To Google! I'm not sure what you mean by 'risk', what's the worst that can happen? Following the crowd is boring, I'd much rather experiment and learn something new. You see a mixed bag of responses when you talk about Rosebud Grates, with some people throwing in the towel when the first experiment isn't successful. This is where the joy of experimentation begins in my opinion. Maybe the gap around the grate is too large, maybe the holes are too small, who knows! The fact that some people get great results from them just shows that you have to get the proportions right, that's all. My guess is that experiments start with holes that are too small and will never provide enough air for the idea to work. I also suspect that the grates often don't fit well enough and air round the outside prevents it being drawn through the holes. From my viewpoint, I really like the idea of the holes being smaller than the bars on a grate where far too much unburnt coal and dust just goes to waste by falling through. Keeping the fuel on the grate until it's completely burnt to ash makes great sense to me, and that's the reason I'm interested in experimenting with it. |
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Post by andyhigham on Nov 8, 2018 18:41:38 GMT
"Manny Gardner" my sweet pea burns really hot and almost no residue gets to the smokebox or down into the ashpan. I put this down to the baffle which acts as a "brick arch" preventing the fire from being sucked down the tubes.
"Chattox", (Martin Evans conway) on the other hand fills the smokebox in next to no time with fine grit like unburnt coal.
When I get half a minute I will experiment with a baffle in Chattox firebox
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Post by Deleted on Nov 8, 2018 19:18:39 GMT
I really love the idea of a Rosebud grate. Whether I love the idea enough to risk it on my first locomotive I don't yet know... I wonder if its been done on a Britannia. To Google! I believe that Jim has tried a rosebud grate on his 5" Brit..not sure on the results though, best ask him... Pete |
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Post by Roger on Nov 8, 2018 21:38:38 GMT
Time to add two 3mm thick pieces of copper sheet to the inside of the firebox edge. The metal block is there so I can centre punch the copper without it bending...  20181108_185327 by Roger Froud, on Flickr ... then the copper strip was held inside nice and flat for drilling right through both pieces at once.  20181108_190551 by Roger Froud, on Flickr Then the rivets were machined to length...  20181108_193433 by Roger Froud, on Flickr ... and squeezed into the small countersink on the inside...  20181108_200654 by Roger Froud, on Flickr ... so it looks like this.  20181108_201433 by Roger Froud, on Flickr  20181108_201441 by Roger Froud, on Flickr The grate is miles too wide, so it needs trimming.  20181108_205116 by Roger Froud, on Flickr Quite a few of the stays were miles too long, preventing the grate from tipping up so they've been filed down so they're no more than 2.5mm above the surface. The ought to be enough to allow the grate to swing up. The ones near the front don't matter, they can stay long unless there's a reason to shorten those too? Maybe it's not good for an exposed end to be too long because it might get too hot and cause thermal degradation of the joint?  20181108_212802 by Roger Froud, on Flickr |
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JonL
Elder Statesman
WWSME (Wiltshire)
Posts: 2,990
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Post by JonL on Nov 8, 2018 22:44:00 GMT
Experimentation is fun if you know what you are doing, I don't, hence I probably better stick to the "Words and music" to start with. For me the fun comes from refining something, so its certainly something I would consider adding in the future, especially once I have a benchmark. At the moment all I have is some frames with some wobbly wheels!
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Post by Roger on Nov 8, 2018 22:54:36 GMT
Experimentation is fun if you know what you are doing, I don't, hence I probably better stick to the "Words and music" to start with. For me the fun comes from refining something, so its certainly something I would consider adding in the future, especially once I have a benchmark. At the moment all I have is some frames with some wobbly wheels! Fair enough, but please don't assume that I know what I'm doing either! I just try to use what experience I have from other projects and a healthy dose of common sense to guide me. Although I do listen to everything other people say, in the end it's my judgement call to make the final decisions. I don't expect to get it right all the time, but most of the fun is in figuring out what are the consequences of the decisions and then seeing how close it was to what I expected. The more often you're right, the more confidence you get in your own judgement. I just have to accept that sometimes I'll fall flat on my face. That's life! |
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Post by David on Nov 8, 2018 23:19:34 GMT
Hopefully some others from down under will chip in here. Our fuel situation went south a few years ago and there has been much experimentation with rosebud grates. Unfortunately I am no help as I have a stainless one but still end up with lots of clinker after a few hours of running, but have no clue why.
There was an article in a recent issue of the local magazine where someone was playing with steam jets to keep the fire bed just off the grate, so plenty of room for you to experiment Roger!
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