Blefuscu Posted March 3 Author Share Posted March 3 1 hour ago, bradfordbuffer said: 1st obstacle is getting it to grow out of build plate.... Actually, one of the problems I've had with V2 is getting it off the plate. One of the rafts shattered when I was scraping it off... so I'm quite surprised at how flexible the final prints are. 1 hour ago, natterjack said: control of distortion and shrinkage Yes, it does feel like witchcraft at times... I've had similar problems working with casting resin and fibreglass but sometimes I just despair with printing! 1 Link to post Share on other sites More sharing options...
bradfordbuffer Posted March 3 Share Posted March 3 (edited) 1 hour ago, Blefuscu said: Actually, one of the problems I've had with V2 is getting it off the plate. One of the rafts shattered when I was scraping it off... so I'm quite surprised at how flexible the final prints are. Yes, it does feel like witchcraft at times... I've had similar problems working with casting resin and fibreglass but sometimes I just despair with printing! Give build plate and model complete a first ipa wash ...(should be good practice anyway to keep wash and cure ipa clear ish) put the plate and model In food bag and whilst the boss if the house not looking pop it in the freezer! Or be a proper man and have a beer fridge in man cave so don't need to sneak around in kitchen freezer! This tip come from my little bro who done some large chess pieces that would not come off plate ...I've never really had a prob just got to be brave and with fine edge spatula give swift splice Personally thought old version of abs type anycubic was better v2 a bit grainy but as you said .....witch craft Just spent 60quid on cults3d on a hole load of files including coach bogies and oca wagon! A late night beckons. G Edited March 3 by bradfordbuffer 1 Link to post Share on other sites More sharing options...
natterjack Posted March 4 Share Posted March 4 11 hours ago, bradfordbuffer said: beer fridge in man cave so don't need to sneak around Reminds me of the Fosters feng shui ads- among my all time favourites. 1 1 Link to post Share on other sites More sharing options...
bradfordbuffer Posted March 4 Share Posted March 4 40 minutes ago, natterjack said: Reminds me of the Fosters feng shui ads- among my all time favourites. Me after a session 3d slicing!😄 1 1 Link to post Share on other sites More sharing options...
andrewshimmin Posted March 4 Share Posted March 4 It looks very nice. Certainly captures the real thing. 2 Link to post Share on other sites More sharing options...
Blefuscu Posted March 16 Author Share Posted March 16 I'm working on the powered DM unit now... this is the first attempt, and has suffered some crude adjustments! Now the bogie is sitting comfortably, I'll reflect these changes on the design and print a real one. 1 1 Link to post Share on other sites More sharing options...
natterjack Posted March 16 Share Posted March 16 1 hour ago, Blefuscu said: I'll reflect these changes Would there be any opportunity to create spaces for ballast (to aid traction)? Link to post Share on other sites More sharing options...
Blefuscu Posted March 16 Author Share Posted March 16 1 hour ago, natterjack said: Would there be any opportunity to create spaces for ballast (to aid traction)? This is a slight issue... It isn't nearly the weight of the die-cast chassis. However... the top half of the metal chassis should still fit. I'm hoping that's enough weight, or ill need to get creative. It will only be pulling the two other units..... 1 Link to post Share on other sites More sharing options...
natterjack Posted March 16 Share Posted March 16 2 hours ago, Blefuscu said: or ill need to get creative FWIW for the 3D (coupled) chassis I'm working on I've been able to provide cradles for steel weight above the drive train (in your case, the bogie). On other projects I've found steel to be nearly twice the useful density of ballast beads such as 'Liquid Metal', and is readily available in handy dimensions as Key Stock. Link to post Share on other sites More sharing options...
Blefuscu Posted March 17 Author Share Posted March 17 I have an offcut of 2mm steel next to that image which I'll be cutting up for reinforceing the trailer chassis, but I also have some 1mm steel shot (it was sold on ebay for weighting teddy bears!) that i use as a metal filler for adhesive or resin and pour into gaps, or into nose cones a la Liquid Metal. Iron fillings would work as a resin filler too I guess. It's just a question of making room for the weight without cutting away too much chassis. Have you found adding the weight above the drive train makes it top heavy? Another option that came up in conversation today at Ally Pally, was having the design 3D printed in sintered steel once I am happy with it. I can't imagine what that's going to cost... but I like really the theory! Link to post Share on other sites More sharing options...
natterjack Posted March 17 Share Posted March 17 38 minutes ago, Blefuscu said: Have you found adding the weight above the drive train makes it top heavy? Whilst I would keep the ballast as low as possible given the sizes, train weights and velocities involved in TT120 I doubt instability would become an issue, there isn't enough room above the rail. That said, in my build (GT3 with slim-ish bonnet profile) I have opted for a tender mounted motor simply to give enough ballast room above the drivers at a reasonably low centre of gravity, just in case! Full trials have not yet been carried out as my preferred 3D print supplier has been rather busy with something he calls 'profitable work'. 1 Link to post Share on other sites More sharing options...
bradfordbuffer Posted March 17 Share Posted March 17 1 hour ago, Blefuscu said: I have an offcut of 2mm steel next to that image which I'll be cutting up for reinforceing the trailer chassis, but I also have some 1mm steel shot (it was sold on ebay for weighting teddy bears!) that i use as a metal filler for adhesive or resin and pour into gaps, or into nose cones a la Liquid Metal. Iron fillings would work as a resin filler too I guess. It's just a question of making room for the weight without cutting away too much chassis. Have you found adding the weight above the drive train makes it top heavy? Another option that came up in conversation today at Ally Pally, was having the design 3D printed in sintered steel once I am happy with it. I can't imagine what that's going to cost... but I like really the theory! How about during slicing the under floor equipment boxes pre slicing hollow out to may be 2mm and add the lattice work corse but thin then large drain hole then after printing fill with buck shot or similar ? Every little bit of artificial gravity helps and can't get any lower than the contactor box! 1 Link to post Share on other sites More sharing options...
Blefuscu Posted March 18 Author Share Posted March 18 20 hours ago, natterjack said: profitable work'. Ha ha, I wish I suffered from that problem! 1 Link to post Share on other sites More sharing options...
Blefuscu Posted March 18 Author Share Posted March 18 20 hours ago, bradfordbuffer said: hollow out to may be 2mm Unfortunately the motor cavity occupies most of the under floor. I even had to add material around some of it where u could see daylight through the floor. I'm trying to keep to at least 2mm thickness, more where possible, for strength (and stability during curing ). That said, metal filled resin is structurally a better bet than the UV resin. I was going to finish cleaning the design up tonight, but I tripped on the way to a hospital appt and now I'm in a&e 😂 When it's finally ready, i will get a quote for sintered metal, if for nothing else than general amusement! 3 Link to post Share on other sites More sharing options...
natterjack Posted March 18 Share Posted March 18 8 minutes ago, Blefuscu said: Unfortunately the motor cavity occupies most of the under floor. I even had to add material around some of it where u could see daylight through the floor. Old school motor bogies such as Tri-Ang , which tended t be cast metal, often had an additional ballast saddle astride the motor which in turn had a top pivot mount for the vehicle; thus any additional ballast in or under said vehicle would bear on the vertical centres of the carrying bogies.While this practice has gone somewhat out of style but may well be worth revisiting for lightweight 3D printing. 2 Link to post Share on other sites More sharing options...
Blefuscu Posted March 21 Author Share Posted March 21 On 18/03/2024 at 16:41, natterjack said: Old school motor bogies such as Tri-Ang , which tended t be cast metal, often had an additional ballast saddle astride the motor which in turn had a top pivot mount for the vehicle; thus any additional ballast in or under said vehicle would bear on the vertical centres of the carrying bogies.While this practice has gone somewhat out of style but may well be worth revisiting for lightweight 3D printing. That might be worth looking at... although I expect the old tt bodies were a little wider? I'm printing chassis V2 now, for a test fit, and once it's running I'll have a look at where I can pile the weight on. Although the quote from JLCPCB for a SLM printing chassis on stainless steel is about £23!!!... that's hard to resist. I need to double check it's the right size, as protolabs' quote was x10 that, and the postage will be awful, but it's stainless steel! Link to post Share on other sites More sharing options...
natterjack Posted March 21 Share Posted March 21 2 hours ago, Blefuscu said: although I expect the old tt bodies were a little wider? Indeed, Tri-Ang TT outline was about the same width as TT20 European/USA; and why such as cheapish, old BTTB chassis are also be too wide for unmodified use in UK outline TT120. I wonder if anyone with the new Hornby HST has stopped their drooling for long enough to look at the conversion potential of the chassis? That may be of considerable wider interest as larger outline bodies will have no problems fitting over the Hornby mechanisms. Link to post Share on other sites More sharing options...
Red Devil Posted March 22 Share Posted March 22 22 hours ago, natterjack said: Indeed, Tri-Ang TT outline was about the same width as TT20 European/USA; and why such as cheapish, old BTTB chassis are also be too wide for unmodified use in UK outline TT120. I wonder if anyone with the new Hornby HST has stopped their drooling for long enough to look at the conversion potential of the chassis? That may be of considerable wider interest as larger outline bodies will have no problems fitting over the Hornby mechanisms. I'd have thought the HST bogies would be perfectly useable in an awful lot of 120 diesels, the (real) bogies being less than 10mm longer than the 8ft 6in used in a lot of the BR BO-BO types, the bogie centres being a bit further apart on them, so they'd need a bit of work on the chassis front. 1 1 Link to post Share on other sites More sharing options...
Blefuscu Posted March 23 Author Share Posted March 23 16 hours ago, Red Devil said: I'd have thought the HST bogies would be perfectly useable in an awful lot of 120 diesels, the (real) bogies being less than 10mm longer than the 8ft 6in used in a lot of the BR BO-BO types, the bogie centres being a bit further apart on them, so they'd need a bit of work on the chassis front. Yes, i think the wheelbase is very useful... I think we will need to wait a while for the drooling to subsist though! I expect I could have used them for the 313, as i don't think the HST bogie is far off the BX1. The halling 21mm bogie was also a candidate, and the ICE3 is also in the same ballpark... Though, with the ICE3 I also get a pantograph (it's not right, but it's useable). I'm fairly happy with version 3 of my ICE3 conversion chassis. Not sure how long the 3D printed drive shafts will last. I have been cutting lumps off the metal top plate... but I have given up getting it to fit, so weight might be even more of a problem. Otherwise I just need to position the couplings, change the bogie sides and fit the bogie pickups. I have also decided to reprint the body in ABS V2, and with a support mesh in the windows, to see if I can improve those wobbly window frames. 5 Link to post Share on other sites More sharing options...
natterjack Posted March 23 Share Posted March 23 1 hour ago, Blefuscu said: to see if I can improve those wobbly window frames. If you have a range of models in mind then photo-etch for detail items may become practicable? In the London area I have found 4DModel Shop to be very cooperative and may well be worth a 'collaborative consultation', https://modelshop.co.uk/ . 1 Link to post Share on other sites More sharing options...
Blefuscu Posted March 23 Author Share Posted March 23 50 minutes ago, natterjack said: If you have a range of models in mind then photo-etch for detail items may become practicable? In the London area I have found 4DModel Shop to be very cooperative and may well be worth a 'collaborative consultation', https://modelshop.co.uk/ . 50 minutes ago, natterjack said: If you have a range of models in mind then photo-etch for detail items may become practicable? In the London area I have found 4DModel Shop to be very cooperative and may well be worth a 'collaborative consultation', https://modelshop.co.uk/ . Etched windows are probably sensible answer. Thanks for the recommendation. I know 4D... but I hadn't thought to look there. The 'new' windows are looking pretty good from what I can see so far... but the rest of it is still printing. Link to post Share on other sites More sharing options...
Blefuscu Posted March 23 Author Share Posted March 23 This is mostly procrastination. I just wanted to put it on some rails... and it looks like I'll be able to make it round corners. I picked up some of the Hunt 009 close couplings from West Hill at Ally Pally. I think they'll do... they appear to have been 3D printed, so I might pick up some magnets on ebay and do my own next time. (The second trailer isn't higher, it's bowing in the middle. That will be fixed with a metal plate.) 2 Link to post Share on other sites More sharing options...
bradfordbuffer Posted March 23 Share Posted March 23 15 minutes ago, Blefuscu said: Etched windows are probably sensible answer. Thanks for the recommendation. I know 4D... but I hadn't thought to look there. The 'new' windows are looking pretty good from what I can see so far... but the rest of it is still printing. Top draw stuff will I'm sure your wobbly frames will stiffen up on putting the windows in? Link to post Share on other sites More sharing options...
Blefuscu Posted March 23 Author Share Posted March 23 1 hour ago, bradfordbuffer said: Top draw stuff will I'm sure your wobbly frames will stiffen up on putting the windows in? That's what I'm hoping... but id prefer to get myself to a better starting point. These ones are also pretty straightforward to fix. However, if I can work out a way to mitigate some of this warping now, it might help with the coaches later. The results looked pretty good out of the printer, but after washing some of the support meshes look pretty wavy! Once it's dried and I've cleaned it up a bit I'll post an image 1 Link to post Share on other sites More sharing options...
Blefuscu Posted March 23 Author Share Posted March 23 Hmm... I don't think window webbing has helped at all. It might even have made it worse. The drivers window is completely straight, but the frame there is only 4mm long. The passenger windows are approx 12mm. I'm a bit puzzled because they looked OK in the printer, (Albiet covered in goo), but also the fact that they have bowed outwards suggests they expanded post printing??... ABS v2 is water based, and i gave them a good wash, but is it also hygroscopic? I did a quick search and the answer looks like it is... https://blog.honzamrazek.cz/2021/05/i-tested-how-much-moisture-sla-printers-resins-absorb-how-it-changes-them/ The improved cross braces seem to have been pretty successful though, so i'll keep these. I don't i'll rerun the window experiment though. 3 Link to post Share on other sites More sharing options...
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