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Post by andyhigham on Jun 10, 2020 14:58:07 GMT
Did anyone think of electrostatic powder coating? It gets into every nook and cranny with an even coat
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Post by Roger on Jun 10, 2020 15:50:37 GMT
Did anyone think of electrostatic powder coating? It gets into every nook and cranny with an even coat Yes, we did discuss that. I was involved with the Honda Spray line at Swindon where it was used with spray turbines that we used to repair. It's not really practical in a home workshop, mainly because of the dangerously high voltages required to charge the paint.
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Post by 92220 on Jun 10, 2020 16:18:34 GMT
Yes. That's a problem I've come across. Nobody makes one with a fan pattern. The main reason is that most airbrushes are used for spraying ink, which is what they were originally designed for, and to make an airbrush spray a fan pattern would make them very much more expensive than they are because extra air jets would have to be added just like on a fullsize spray gun nozzle.
Now that is what I believed up until 2 minutes ago!!!!! I've just been onto the 'net and asked if anyone makes a fan pattern airbrush. They ARE made. An American company called Grex do a Youtube video of using a fan pattern airbrush. Along with that info is the fact that Iwata, manufacturers of top-end industrial spray guns also advertise and show off an Iwata airbrush with a fan pattern spray head. Interestingly, both these companies airbrushes use a trigger mechanism to operate, just like a mini spray gun, but airbrush size. There are others too. I have to admit that until now I was way behind the times with airbrushes. They have definitely been improved upon these last few years!! Both the airbrushes mentioned can spray either cone shapes or fan shaped spray patterns. There do appear to be a number of manufacturers of airbrushes that spray fan patterns. However, they are around double the cost of a normal cone pattern airbrush. The Iwata, for instance, costs $379.00US. That's £297.00 at today's exchange. OUCH!! I was right when earlier I said that the cost of a fan pattern airbrush would be much more expensive.
Bob
Sorry. For some reason I didn't get the quote section included. This post is regarding what nonort posted about fullsize spray guns having the ability to spray fan patterns.
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Post by 92220 on Jun 10, 2020 16:27:37 GMT
Hi Roger. Fixing screws onto an already painted surface, is always tricky. With our loco building there is no way that you won't come across this problem. This is where having the minimum thickness paint coat while having full opacity, is the trick. You should then wait AT LEAST 4 weeks before screwing onto a newly painted surface. The 4 weeks is the MINIMUM time that white-spirit based paint (enamels) take to go through their chemical changes and fully harden off. I can't speak for other brands but Phoenix Paints are vehicle enamels. They will eventually go as hard as the paint on your car, while still being flexible enough to not crack easily. My original test when I was looking at types of paint to make, was to brush a coating onto a piece of gloss art paper and leave to dry, and harden, for a month (actually I think it was a couple of months because I forgot it). I then rolled it around a pencil to see if it would crack, which was asking a lot of it!! It didn't crack, so I was happy to go ahead with the vehicle enamel as the basis for the paint. As far as spraying the fully assembled frames goes, it is a lot easier than you think. The airbrush puts on such a fine coat, and it is inside the frames, which, even as a bare assembly, isn't easily scrutinised, so stopping the spray pass while still over a surface, isn't as much of a problem as it would be painting the boiler or tanks, where the surface can be critically viewed. Obviously, if you can spray something and stop the spray off the surface of the part, that is the best way....but it is not always possible. As far as spraying into a corner goes, You will need to reduce the pressure and reduce the spray cone to get into the corners without putting too much paint on. Build up slowly. Playing around with the pressure and spray cone is an important practice for painting locos. Even on a 5" g loco, there will be times when you have to adjust the spray cone down to as little as 1/2" at around 2" distance. On the odd occasion, even smaller; but you will need practice to make sure you don't spray too much paint on in one area. Bob. Hi Bob, I didn't really appreciate how much you would need to adjust pressure and spray pattern to achieve the results you need. I get it now. There are some places, such as between the gussets on the corner angles where you need to direct a small cone at low pressure between them to have any hope of getting paint into such a small space. At least, that's my understanding of what you're suggesting. I'll have to do a bit of experimentation to see how that adjustment goes. Hi Roger. Yes that is the way you can airbrush into a tight space. That is the advantage of a cone shaped spray pattern. At least the paint all goes where you want it to. However, a fan pattern spray would be best for tanks, tenders and boilers if affordable. Bob.
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Post by 92220 on Jun 10, 2020 16:45:36 GMT
I've been digging to find out more about fan pattern airbrushes. Paache make good airbrushes and they also make a fan pattern nozzle to fit 2 of their units......all at reasonable prices. Amazon sell Paache airbrushes and also the fan pattern nozzle as an 'extra' at £18.00. They fit the Paache TG airbrush (around £67.00) and TS airbrrushes (around £77.00).
Bob.
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Post by simplyloco on Jun 10, 2020 16:51:30 GMT
Hi Bob, I didn't really appreciate how much you would need to adjust pressure and spray pattern to achieve the results you need. I get it now. There are some places, such as between the gussets on the corner angles where you need to direct a small cone at low pressure between them to have any hope of getting paint into such a small space. At least, that's my understanding of what you're suggesting. I'll have to do a bit of experimentation to see how that adjustment goes. Roger. The acknowledged 'nice' finishes on the Brit and now the Stirling were achieved with my Kite mini spray gun which will produce a dead accurate two inch fan. It has a 0.4mm nozzle. I have two high quality airbrushes, but the paint has to be so thin that you will land up making lots of coats to get any opacity. In addition, the waiting time between enamel coats is a real pain, one of the reasons I switched to 2k paint. The 2k boiler wrapper on the Stirling was done in just two coats and is now 'Diamond Hard' after just a week or so! John www.buckandhickman.com/en/shop/products/details/6460734/FIAC-KITE-MINI-GRAVITY-SPRAY-GUN-1.0MM
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Post by Roger on Jun 10, 2020 18:17:38 GMT
Hi Bob, I didn't really appreciate how much you would need to adjust pressure and spray pattern to achieve the results you need. I get it now. There are some places, such as between the gussets on the corner angles where you need to direct a small cone at low pressure between them to have any hope of getting paint into such a small space. At least, that's my understanding of what you're suggesting. I'll have to do a bit of experimentation to see how that adjustment goes. Roger. The acknowledged 'nice' finishes on the Brit and now the Stirling were achieved with my Kite mini spray gun which will produce a dead accurate two inch fan. It has a 0.4mm nozzle. I have two high quality airbrushes, but the paint has to be so thin that you will land up making lots of coats to get any opacity. In addition, the waiting time between enamel coats is a real pain, one of the reasons I switched to 2k paint. The 2k boiler wrapper on the Stirling was done in just two coats and is now 'Diamond Hard' after just a week or so! John www.buckandhickman.com/en/shop/products/details/6460734/FIAC-KITE-MINI-GRAVITY-SPRAY-GUN-1.0MMHi John, Thanks for that, I'd be interested to hear Bob's thoughts on that one for larger surfaces. Bob has mentioned that you don't have to wait between coats though with the Air brush, you can do one side, then to the other and then return to the first side to do it all in one session.
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Post by chris vine on Jun 10, 2020 18:45:08 GMT
Hi Roger,
There is lots of talk about using airbrushes here. I am not sure why.
When painting the frames, you can use lots of thin layers, to mist on the paint. Then you can go at different places from different angles to build up the paint - in one session. This is all fine as long as you are not spraying gloss paint. So for the frames, probably with a satin finish paint, you can mist it on in thin layers, maybe even with more thinnners and build it up slowly and in a controlled manner. Yes, the paint will get into corners behind nuts etc.
However for full gloss paint, and especially with enamel paints, you have got to apply the paint fast and in quite a heavy coat. If you mist them on in thin coats, they will not pull out flat and you will end up with a nasty mess of ripples and orange peel. If you were spraying cellulose I think you could mist it on and, in later coats, use much more thinners as the whole lot will meld together and pull out flat. However enamels are a different kettle of fish altogether.
The only gun I tried with a bottom style cup was a nuisance because so many jobs only require a small quantity of paint which then gets left in the bottom of the cup. Or the gun draws air just when you need paint! So my advice (whatever you choose) is to get something with the cup on top.
As for putting nuts/bolts onto a painted surface: I always chamfered the undersides so that it presented a round face to the paint. Then as you tighten them up gently, they don't "mill" the surface. Incidentally, on our models, I have found that you don't need to tighten things up very tight - especially on painted parts. Firstly they probably don't carry a very high load, and the paint acts as a nutlock!
When putting on transfers (or later coats of anything, eg varnish over transfers), you really want to have allowed the panel to have done much more than just dried. You need the paint to have properly cured, IE polymerised, or whatever it does. Then, if you make a mistake (like I did all the time!), you can wipe it off with a cloth - just dampened with thinner. If the underlying paint has only "dried", you will take that off too.
For modern car paints, they can be made to cure/harden very quickly. Data sheets will tell all. For the enamel paints which we model engineers are most used to, they take a long time. I made a cardboard "oven", with a low power heater inside, so the parts could cure at perhaps 40C for a month or two. There was plenty to get on with on other parts, but by the time I came to line out the tender for example, I knew that the panels were really solid. All (many) mistakes could be gently wiped away. (I also had test pieces which were in with the main parts which I could experiment on!).
But my main point is that if you want to paint gloss paint (without horrible ripples) you have to apply it quickly and not mess about!
If you are worried about getting under some parts (eg steps on the back of a tender) you can get round this if you make up my turnover stand gadget. Yes, you will end up a bit too much paint in some places maybe, but if you keep it turning about a horizontal axis it won't run and you won't see that some parts are a little thicker.
Also, I often see advice to thin the paint with more thinners to make it flow out better. This only works up to an extent. The problem is: if as you add more thinners it will flow but sag/run even more easily. Also, as it dries you will find that any rubbing down marks will start to show through. The paint film gets so much thinner as the solvents (extra thinner) evaporate that the dry film thickness isn't enough to cover previous rubbing down marks. If you were painting with a satin finish you would not be able to see these tiny marks because of the duller surface. But with gloss (which will look wonderful on your precision platework) it shows up all imperfections underneath! My feelings are that this is why so many model engineers think that satin looks better. However, your platework is a new form of artistry and will, I think, look wonderful in perfect gloss.
Hope this helps! chris.
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Post by coniston on Jun 10, 2020 21:04:57 GMT
Hi Roger, I agree whole heartedly with Chris Vines comments and to add to that I use a similar gun to John (Simplyloco) certainly for the boiler, cab and tanks. The last two locos I painted I used a mini spray gun exclusively, I really don't think you'll get enough paint on in a wide enough pattern with an airbrush to achieve an even gloss finish. Possibly an airbrush is ok for the inside of the frames but outside frames I would also use the mini spray gun, also known as a touch up gun. These are used extensively in the auto trade for panel repair touch-ups, the top feed is more convenient and you can at least get enough paint in it to complete a substantial amount of the work without having to keep mixing / thinning more batches. Also as mentioned in other posts the fan pattern will give you a much more even finish. If you use an internal mix airbrush you have the problem of trying to maintain an even paint flow with the trigger, not easy when you're trying to concentrate on what you are painting. Air brushes as someone has mentioned are really an alternative to a brush used for art work, not really designed for one colour coverage.
Most important is to use the correct thinners, for enamel use a proper quick air dry thinners and whatever you don't use white spirit or similar. As Chris says don't over thin thinking it will dry quicker, it wont but will create runs and curtains, quite often sometime after you finish painting so don't notice it until too late. When doing the light 'dusting' coats make sure it hasent dried before hitting the surface, you should be able to smudge it with a finger and not feel it as a gritty surface. A bit of practise on some scrap metal will soon get your settings right. For cleaning I buy cheap 'gun wash thinners' basically a less refined cellulose, ideal for making sure everything is cleaned. Word of warning against 2K paint, it is extremely dangerous and contains Cyanide, you MUST use an air fed aspirator with it.
I'm sure you'll master it in your usual pragmatic way, good luck it is a really rewarding part of the build.
Chris D
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Post by d304 on Jun 10, 2020 21:52:06 GMT
Hi Roger
I have finished spraying my side tanks and running boards for my loco. Where I am in Australia the days are now running from -3 to 14c and I wanted to finish the tanks and let the sit for a few months before lining. Because of the cold I preheated the pre mixed auto paint cans in hot water and had the parts heating in a heated box. Immediately after each part was sprayed, heavily as Chris recommends, I kept the part moving around so the paint wouldn’t run or gather (Chris again) and the finish was glass like. The parts then went back to another heated box. The only problem seems is the over spray at the corners as the next corner was sprayed, leaving a Matt finish.
One problem I came across was dripping water. Initially I thought it was water dropping from the can as it came out the water. When I took the respirator off when finished, there was a lot of condensation inside the mask that would drip through the bottom valve. No water fortunately dropped on the parts!
David
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Post by d304 on Jun 10, 2020 21:58:33 GMT
Also when I sprayed the frames without the buffers. I machined some tapered bushes that went into the holes for the buffers without touching the top surface. The frame was then returned to the rotisserie for spraying.
David
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Post by Roger on Jun 10, 2020 22:55:26 GMT
Thanks to all, and lots to think about. There's an awful lot of fine detail on 1501 that I can't see being painted with a large gun though. Sure, there are a couple of bigger parts that might benefit from that treatment, but I can see using the Airbrush for much of it. We'll see, I'll just have to try things out and see how it goes. Bob doesn't seem to have any difficulty in using an Airbrush for everything, so maybe it's just a matter of technique? Who knows, there's certainly a lot to learn!
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Post by Roger on Jun 10, 2020 23:07:55 GMT
Here's another outstanding job finally being done. This time it's the heat shield for the rear axle which hopefully will dramatically reduce the temperature it's exposed to. This is a piece of 0.5mm thick Stainless Steel shim which will sit 2.2mm below the ashpan. 20200610_225218 by The train Man, on Flickr Here I'm setting it up ready for spotting through the 2mm fixing holes. 20200610_231815 by The train Man, on Flickr This is the position it will end up in. I'm just using some 2mm aluminium offcuts to space it somewhere near where it needs to be. I'll guillotine it to length when I know it's in the right place. 20200610_231828 by The train Man, on Flickr 20200610_234215 by The train Man, on Flickr This wants to tip over, so I'm using threaded rods from the clamping set to prop it up. 20200610_234656 by The train Man, on Flickr These are the Stainless Steel standoffs that will be riveted or tacked with the TIG welder to hold it in place. I'm still undecided as to whether to put Ceramic insulation in-between the two sheets or whether that will result in the inner plate getting too hot. 20200610_235726 by The train Man, on Flickr
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oldnorton
Statesman
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5" gauge LMS enthusiast
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Post by oldnorton on Jun 11, 2020 9:35:35 GMT
Roger
Very interesting comments from others about airbrushes and the need for a larger gun as well, which I totally agree with. Yes, the air brush is ideal for painting smaller things like wheels and inside frames. Also useful for applying etch primer to surfaces with small detail like rivets so that a minimal amount of paint is applied.
But an airbrush cannot 'wet' a surface of more than 3" x 3" when applying gloss. You need one of the smaller guns with a top canister as recommended previously for the sides of tanks, the cleading, the smokebox, etc. There are several available and I have some £30 ones that work fine. They often come with a standard 1.0mm needle and nozzle but you need to buy an extra 0.6 or 0.5 or even the 0.4mm as mentioned. Then it will spray paint at about 'airbrush x 4' rate.
I am just repeating the already said good advice from both Chrises and others. Oh, and practice for several days on all manner of scrap pieces before testing on the engine. After some painting jobs are done I usually think to myself "I've got the hang of it now and could do it better if I started again"!
Norm
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Post by ettingtonliam on Jun 11, 2020 10:38:54 GMT
I wonder what LBSC would have made of all this? The late AJ Reeves, who knew him well, once told me that once he'd built and run an engine, he would wash it down with paraffin(!) and give it a brush applied coat of red/black/green, (probably Valspar or Humbrol) as appropriate. Given that he didn't tend to use boiler lagging, this would be direct on to the copper boiler, no etch primer, just brushed straight on. Apparently he said he'd never noticed any difference in performance after it had been painted, and performance was all he was really interested in.
Were Martin Evans, Ken Swan, Don Young, Keith Wilson etc fussy about paint?
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Post by Roger on Jun 11, 2020 12:10:11 GMT
Roger Very interesting comments from others about airbrushes and the need for a larger gun as well, which I totally agree with. Yes, the air brush is ideal for painting smaller things like wheels and inside frames. Also useful for applying etch primer to surfaces with small detail like rivets so that a minimal amount of paint is applied. But an airbrush cannot 'wet' a surface of more than 3" x 3" when applying gloss. You need one of the smaller guns with a top canister as recommended previously for the sides of tanks, the cleading, the smokebox, etc. There are several available and I have some £30 ones that work fine. They often come with a standard 1.0mm needle and nozzle but you need to buy an extra 0.6 or 0.5 or even the 0.4mm as mentioned. Then it will spray paint at about 'airbrush x 4' rate. I am just repeating the already said good advice from both Chrises and others. Oh, and practice for several days on all manner of scrap pieces before testing on the engine. After some painting jobs are done I usually think to myself "I've got the hang of it now and could do it better if I started again"! Norm Hi Norm, Thanks for that, all useful thoughts. I do have a small gun that I've borrowed, so that's definitely an option. However, I'll be interested ot hear Bob's comments on how big an area he's painted with an Airbrush, because he seems to do everything with it.
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Post by Roger on Jun 11, 2020 12:14:18 GMT
I wonder what LBSC would have made of all this? The late AJ Reeves, who knew him well, once told me that once he'd built and run an engine, he would wash it down with paraffin(!) and give it a brush applied coat of red/black/green, (probably Valspar or Humbrol) as appropriate. Given that he didn't tend to use boiler lagging, this would be direct on to the copper boiler, no etch primer, just brushed straight on. Apparently he said he'd never noticed any difference in performance after it had been painted, and performance was all he was really interested in. Were Martin Evans, Ken Swan, Don Young, Keith Wilson etc fussy about paint? I don't suppose LBSC had any options when it came to painting other than using a brush. I'm sure you can get a perfectly acceptable finish like that, and if there's as little detail as LBSC had, then life is much easier anyway. However, times have changed, and people are adding ever finer detail on their models. There's not much point in going to the next level of detail and then obscuring it with a thick layer of paint. I don't think LSBC cared much what locomotives looked like. He certainly didn't have much interest in reproducing anything but the most basic outline, and even that wasn't even close to scale on SPEEDY. His comment of 'bears more than a passing resemblance...' really say it all. Each to their own, he was more interested in small gauge locomotives which were of necessity very much simplified. I think this is why SPEEDY looks the way it does. Personally, I think he'd embrace these more modern practices if he felt they could be quickly mastered by the amateur though, he was very forward thinking.
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Post by simplyloco on Jun 11, 2020 12:20:47 GMT
Hi Norm, Thanks for that, all useful thoughts. I do have a small gun that I've borrowed, so that's definitely an option. However, I'll be interested ot hear Bob's comments on how big an area he's painted with an Airbrush, because he seems to do everything with it. That may well be the case, but he's been around paint since Noah filled the Ark! John
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kipford
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Building a Don Young 5" Gauge Aspinall Class 27
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Post by kipford on Jun 11, 2020 13:09:19 GMT
Whilst I agree with John et al, a mini-gun is preferable and I intend to go that way for my Aspinall. You can spray large areas with an airbrush, The Hurricane in the picture is 60" wingspan and was sprayed entirely with an airbrush with a smallish gravity feed cup. It takes time and you haver to be accurate with your tracking because of the small cone angle, rather than the fan and it takes a lot of passes. Dave DSCN0355 by Dave Smith, on Flickr
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Post by chris vine on Jun 11, 2020 14:42:38 GMT
Gosh, that Hurricane is beautiful!!
I think you managed fine with an airbrush because you were not painting gloss paint. You can approach the job in a steady and methodical manner and get an excellent result. With gloss, especially the viscous enamel types, you have to be bold and quick. That is when a spray gun with a big enough nozzle seems to be necessary.
Chris.
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