mickoo
Western Thunderer
There will only be one
, well two actually, the test build and one production unit.
7mm Mickoo's Commercial Workbench
- Thread starter mickoo
- Start date
, well two actually, the test build and one production unit.
mickoo
Western Thunderer
End of week update on the full metal jacket BLP. Test prints of the 3D top have gone rather well, this one is for fit around the gutter and cab front, a quick scoosh of red oxide reveals how proud the surface details are, currently they're 0.2 mm to match the side skin, I may drop them down to 0.15 on the next rendition. The current test print is 0.2 mm wider to give a gutter overlap but that may be too much and I might revert to 0.1 mm over width or retain this width.
The side view shows the important whale hump on BLP casings as it rises up 3" to go over the safety valves, it also shows I need to move the rivets on the roof to line up with the side sheet which is just held on with double sided tape. These side sheets have a few small errors at the front which new etches on order will resolve.
The safety valve recess is the wrong shape and size, since corrected on the current print, I've also added a few more details in there to sparkle it up a bit.
The next print is extended even further up past the whistle recess, each prints adds new features, all of which can have an impact on the upper surface quality so it's slowly slowly catchy monkey.
The side view shows the important whale hump on BLP casings as it rises up 3" to go over the safety valves, it also shows I need to move the rivets on the roof to line up with the side sheet which is just held on with double sided tape. These side sheets have a few small errors at the front which new etches on order will resolve.
The safety valve recess is the wrong shape and size, since corrected on the current print, I've also added a few more details in there to sparkle it up a bit.
The next print is extended even further up past the whistle recess, each prints adds new features, all of which can have an impact on the upper surface quality so it's slowly slowly catchy monkey.
mickoo
Western Thunderer
End of week update on the Bulleid Pacific, very little obvious progress, mostly pipework and fittings and a little sheet work, just waiting on some cab interior ribbing etches to finish that area off.
Most of the week was spent in 3D sorting out the front end of the roof, optimizing orientation and shape to fit the metal casing with the minimal of visible joints/filling. That's all done now so just need to fill the gap between front and rear test sections, add details and set up for the mega 14hr print.
I'm still waiting for the new casing etches to arrive at the end of the month, they have the new front plate with the smoke box door opening raised to the correct height. It's a simple shape so I may well get bored and whip this one off and hand cut a new one in the mean time, that'll leave one casing complete for another model. Some one asked if there was a chance of a Giesl option, it was churlish not to try, it still needs tweaking until I'm happy with the shape, but yes, a Giesl option is viable which will also need a new smoke box interior module.
The two front ends here were not at optimum quality for detail, they're just to test for fit. You'll see really bad layering on the front cowl, that gets minimized at the optimum angle and even more so if I lowered the layer depth to say 30 or 10 microns. Frankly it's on a smooth surface with no surface detail (planned that way, I call it pushing the error to an area easiest to clean up ) that it's easier to just sand smooth with wet n dry.
Most of the week was spent in 3D sorting out the front end of the roof, optimizing orientation and shape to fit the metal casing with the minimal of visible joints/filling. That's all done now so just need to fill the gap between front and rear test sections, add details and set up for the mega 14hr print.
I'm still waiting for the new casing etches to arrive at the end of the month, they have the new front plate with the smoke box door opening raised to the correct height. It's a simple shape so I may well get bored and whip this one off and hand cut a new one in the mean time, that'll leave one casing complete for another model. Some one asked if there was a chance of a Giesl option, it was churlish not to try, it still needs tweaking until I'm happy with the shape, but yes, a Giesl option is viable which will also need a new smoke box interior module.
The two front ends here were not at optimum quality for detail, they're just to test for fit. You'll see really bad layering on the front cowl, that gets minimized at the optimum angle and even more so if I lowered the layer depth to say 30 or 10 microns. Frankly it's on a smooth surface with no surface detail (planned that way, I call it pushing the error to an area easiest to clean up ) that it's easier to just sand smooth with wet n dry.
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Big Train James
Western Thunderer
Two questions from this ignorant foreigner. What differentiates a Giesl equipped loco from a non-Giesl equipped variant? And is that overhang above the smokebox door intended to improve draft or function as a smoke lifter? I never realized it was open front to back.
mickoo
Western Thunderer
Giesl is a specific type of exhaust ejector that improves draft and draw on the fire, it's an arrangement of thin slots in one long row, as opposed to the traditional round type of ejector. The shroud inside came down very low to the ejector and created a venturi effect. It's very efficient and the designer (Austrian) knew this and patented it globally, therefore other railroads had to pay handsomely to use it. Sadly it came too late in the day to have a global impact on steam, though it's use was wide spread in countries that retained steam longer than most, East German had quite a few as did Rhodesia and South Africa.
Standard (not quite) draughting with big gap between petticoat and ejector. Bulleid used the lemaitre 5 port type which was also efficient but gave a very soft exhaust, hence the gap in the front cowling to help lift smoke.
Giesl with long petticoat.
A more standard set up is seen on the B1 with a single port opening.
That's the usual arrangement of daughting, though engines with double chimneys have two corresponding ports and I've seen drawings and photos of some Union Pacific FEF3's with three ports and triple chimneys.
The cowl has a thin slot at the front and the sheet plate work is sloped in an aid to generate an up draft, in the early days the engines suffered very badly with smoke clinging to the roof line and drifting down over the cab windows, there were lots of trials and tests to try and improve the situation, they sort of worked but I don't think it was ever resolved 100%. To be fair the issue of smoke being pulled down afflicted other types of engine, some worse than others.
Standard (not quite) draughting with big gap between petticoat and ejector. Bulleid used the lemaitre 5 port type which was also efficient but gave a very soft exhaust, hence the gap in the front cowling to help lift smoke.
Giesl with long petticoat.
A more standard set up is seen on the B1 with a single port opening.
That's the usual arrangement of daughting, though engines with double chimneys have two corresponding ports and I've seen drawings and photos of some Union Pacific FEF3's with three ports and triple chimneys.
The cowl has a thin slot at the front and the sheet plate work is sloped in an aid to generate an up draft, in the early days the engines suffered very badly with smoke clinging to the roof line and drifting down over the cab windows, there were lots of trials and tests to try and improve the situation, they sort of worked but I don't think it was ever resolved 100%. To be fair the issue of smoke being pulled down afflicted other types of engine, some worse than others.
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Big Train James
Western Thunderer
Thank you for the explanation Mick. 
Lancastrian
Western Thunderer
James,
The Giesl ejector was designed to overcome problems with multijet blastpipes, like Kylchap. There were 7 nozzles arranged in line, which fanned out and were directed into the oblong body of the chimney. Supposed advantages were an 8% increase in efficiency and a 20% increase in power. Tests carried out on 9F's, and also one of the Tallylyn locomotives were inconclusive. One side effect of the Giesl ejector, apart frim the increase in suction and drafting was the suppression of sparks being thrown, so a spark arrestor was not required.
Ian
The Giesl ejector was designed to overcome problems with multijet blastpipes, like Kylchap. There were 7 nozzles arranged in line, which fanned out and were directed into the oblong body of the chimney. Supposed advantages were an 8% increase in efficiency and a 20% increase in power. Tests carried out on 9F's, and also one of the Tallylyn locomotives were inconclusive. One side effect of the Giesl ejector, apart frim the increase in suction and drafting was the suppression of sparks being thrown, so a spark arrestor was not required.
Ian
Pencarrow
Western Thunderer
I strongly suspect this is heading towards the definitive rendition of a BLP (until you better yourself on the next one
). The Giesl option really makes it stand out as something special IMO. Absolutely cracking work, I hope you're pleased with what you're achieving Mick.
mickoo
Western Thunderer
No quite sure there, I'm sure there are many other good renditions out there, I'm just doing things a little different.I strongly suspect this is heading towards the definitive rendition of a BLP (until you better yourself on the next one
I'm happy with the 3D, but then I'm a vociferous advocate
The Geisl was just for giggles really, someone on FB asked if it was possible and it was. It had been discussed within F7 to try and convert the existing resin shell but it's hard work blending in new parts, ideally you need to start afresh.
mickoo
Western Thunderer
Folks, this is why you spend weeks feeding the bin monster with test shots. The real McCoy, 23 + hour print perfectly straight with imperceptible surface defects or artifacts <smug mode ON>.
It did highlight two problems I've not encountered before, a tub big enough to wash it in and it barely fits in the curing cabinet.
The slight banding you can see is colour and not tactile, Fast Navy Grey (FNG) needs to be well stirred before use and starts to separate after about 6-8 hours. With long (time duration) prints the build plate is clear of the vat so you're relying on the actual printed part moving to agitate the resin, it's not very effective so you get a marbling in colour which varies from white to the main dark grey colour.
Tomorrow it'll get all the sacrificial surfaces cleaned up and a blow over in filler primer.
It did highlight two problems I've not encountered before, a tub big enough to wash it in and it barely fits in the curing cabinet.
The slight banding you can see is colour and not tactile, Fast Navy Grey (FNG) needs to be well stirred before use and starts to separate after about 6-8 hours. With long (time duration) prints the build plate is clear of the vat so you're relying on the actual printed part moving to agitate the resin, it's not very effective so you get a marbling in colour which varies from white to the main dark grey colour.
Tomorrow it'll get all the sacrificial surfaces cleaned up and a blow over in filler primer.
Big Train James
Western Thunderer
Indeed, I got a bit of a surprise when I tried to clean my first print that used the whole build volume. My usual method at the time of spraying alcohol on the part rather than dunking it wasn't practical. I eventually settled on dunking in the tub that comes with the wash'n'cure, which I don't use for cleaning in any other situation. Fortunately, the wash'n'cure tub was full of cleaned and reclaimed alcohol, so I dropped the part in and let it soak. I would hate to have to use that much fresh alcohol to clean something.
Pencarrow
Western Thunderer
There can't be too many (steam loco) parts that are so distinctive as a Bulleid roof for a WC / BoB. You've definitely captured the look of it. <smug mode> highly deserved.
simond
Western Thunderer
I use my wash’n’cure every time. I’m going to filter the alcohol (which is FNG coloured) at some point. I must have washed 10 or 15 prints in it so far. I did top it up, a little, over Christmas, and I do use the long tongs to retrieve stuff that falls off the build plate.
mickoo
Western Thunderer
Appreciated
It'll be at Kettering, well at least one of them will, highly unlikely I'll get both finished in time.
It is a good advert but I think the VL80 cab is a better one, I need to revisit that with these new settings and support set up, it may well cure the two small niggles I had on those prints.
mickoo
Western Thunderer
I have two tubs, the primary one for straight off the plate, thick dark grey by now, 20-30 prints no problem. Second tub is clean fresh stuff, same again 20-30 prints and just tuning a darker shade now.
Primary gets dumped outside in a open air tray to dry off and let resin cure in the sunlight, secondary goes into primary and fresh IPA tops up secondary.
I never reuse IPA, clean or strain it, over time it leaves a thin slimy residue. IPA is so cheap, why risk spoiling your prints with it.
OzzyO
Western Thunderer
Simond,
what do you use to filter your alcohol? (I use my liver and kidneys) I did try a water filter for the cleaning fluid in my ultrasonic cleaner but after one or two uses it was time for a new filter.
ATB
OzzyO.
mickoo
Western Thunderer
You don't need the sun, decant into a smaller container, stick that in your cure station, assuming you have one, 30 mins later should be nice and clean.
Mind, I still would not use cleaned IPA twice, many do, but my experience was not conducive to good clean prints second time around, YMMV.
simond
Western Thunderer
Cheers Mick, I looked at the prints I did last night (and washed very hurriedly this morning before leaving for work) and despite the IPA being very grey, they seem to be pretty clean. Have a look at the solebar number plate on my thread, though to be fair it has had a thin wash of grey.
I don’t have a suitable pot to put in the curing station. Might have to go to Wilco or somewhere similar, but probably not before the weekend. Definitely safer than raiding ‘er ladyship’s cupboards…
I guess if I were printing 23 hour specials, I might be a bit more cautious.
Ozzy, I haven’t yet, but I’ll use some cheap coffee filters, or, failing that, I’ll fold some kitchen roll into quarters, and then use that.
I don’t have a suitable pot to put in the curing station. Might have to go to Wilco or somewhere similar, but probably not before the weekend. Definitely safer than raiding ‘er ladyship’s cupboards…
I guess if I were printing 23 hour specials, I might be a bit more cautious.
Ozzy, I haven’t yet, but I’ll use some cheap coffee filters, or, failing that, I’ll fold some kitchen roll into quarters, and then use that.