RMweb Gold farren Posted February 16, 2014 RMweb Gold Share Posted February 16, 2014 I am trying to do the rivets along the water tanks and coal bunker on a LMS 2300 class with the limousine cab, and was wondering the best way to do the rivets? I am using AutoCAD 2013 as i am doing a night course but its half term, Link to post Share on other sites More sharing options...
jonhall Posted February 16, 2014 Share Posted February 16, 2014 You might want an 'array' you select the items you want, choose the type of array you want (I can't remember the options and its not on this PC but one does along a line (or grid) and the other in a circle) then choose the number of rows (1) and columns (lots) and the distance between them, and bingo - a line of the same item. Jon Link to post Share on other sites More sharing options...
Neilgue Posted February 17, 2014 Share Posted February 17, 2014 You can also save the rivet head as a block (even if it is only a circle). This block can then be inserted at intervals along a polyline using the MEASURE or DIVIDE commands. Link to post Share on other sites More sharing options...
flexible_coupling Posted February 17, 2014 Share Posted February 17, 2014 Are you talking about how to actually draw up the shape of a rivet in 3D? I recommend drawing up a 'quadrant' shape of the right radius and height, then use the REVOLVE command (360 degrees) while selecting the centreline as your axis. This will create your little mushroom-head shape, and you can grab the centrepoint of the underside with COPYBASE then paste at points along a line (perhaps using the DIVIDE command to break up your line into an even number of segments). That basic revolve command is extremely helpful in a huge number of applications. Apologies if that's at all condescending/already within your level of knowledge... just not quite sure where you're up to in your skillset! Edit: Neilgue had already pointed out the use of 'divide'. I myself avoid using blocks (can't see the benefit), instead keep 'redundant' copies of any models to one side with elements in place but not joined together in union, just in case I need to pinch a bolt or spring somewhere else... Link to post Share on other sites More sharing options...
RMweb Gold farren Posted February 17, 2014 Author RMweb Gold Share Posted February 17, 2014 I am sure I put a post up but it seems to have diapered. hi flexible couplings, by no means are you being condescending over my head my be, this is my first year doing the AutoCAD course and won't be doing 3D until the 3rd year, jonhall that worked for me a bit of messing about with it to fully understand what it dose and how it works thanks hi Neilgue I will give your way a go on my next drawing but for now I'll stick with one method so not to get to confused the drawing I am designing is to convert the Hornby 2300 class to a limousine Cab variant, so only working in 2D to produce a brass etch, all going well. the idea i had was to just do the sides and cut and stick but i am now wondering if i should do the tank fronts, top the cab front and back and the coal bunker? if so the tank sides and front could be as one with a etch line on the back would this need a to be taken to the over all length? here's where i was up to last night the over all size matches the Hornby model and have been doing the coal bunker today the cab top is wrong as its the height of the Hornby one at the moment and will need shorting for the limousine as the roof come down further. any ideas would be welcome pic below Link to post Share on other sites More sharing options...
RMweb Gold farren Posted February 20, 2014 Author RMweb Gold Share Posted February 20, 2014 can I just run a few things past some one to make sure what I am doing things right, colours am I right in thinking blue is the back half etch for things like folding lines, red is front half etch for rivets and window recesses, white is all the way throw for windows, which levees black for ...?. the other thing how thick dose a bend line need to be and what is the normal size for rivets is ,2 mm to big/ small Link to post Share on other sites More sharing options...
Marbelup Posted February 20, 2014 Share Posted February 20, 2014 The minimum width of a bend line depend on the thickness of the material. I believe the rule of thumb for bending metals in general, is that the effective bend radius at is 1/3 of the thickness, i.e. the metal on the outside of the bend stretches more than the metal on the inside compresses. So, if the metal is half etched on the inside of the bend, you should be able to draw the finished cross section of the bend and measure/calculate the radius at the 1/3 point (of the half thickness) and "unfold" the bend to determine the necessary shape before it is folded, and hence the required minimium groove width - sufficient to allow the metal to be folded without the groove closing up completely. I went through this excercise about 10 years ago when I design some etched items, and it worked. I am sure people who do artwork all the time have this all worked out, but this method will work as it is based on basic first principles. Are the rivets going to be proud on the front surface with everything else etched to half depth, or a half-etched hold on the back to allow the rivet to be pressed put? If the latter, I suggest 0.4 - 0.5 might be closer to the mark as the hole needs to be big enough to allow use of a scriber or similar to push the rivets out. Link to post Share on other sites More sharing options...
Gt.Shefford Posted February 20, 2014 Share Posted February 20, 2014 Check out PPD's site (http://www.ppdltd.com/DG_How_2_draw.html) very clear guide on the preperation of artwork for etching. Used them myself for the 08-16 kit. For half etch fold lines I tend to use the thickness of the material, so if the part is etched in say 10 thou. (0.2mm) brass I would make the half etch fold lines 0.2mm Jonathan Link to post Share on other sites More sharing options...
RMweb Gold farren Posted March 12, 2014 Author RMweb Gold Share Posted March 12, 2014 thanks for your all replays have not had much time to do a lot on the drawing of late with course work taking up the time. I did send a email to the PPD before i had any reply's here and they said the same tends to be the thickness of the material for folding lines. i do have two more questions the first what thickness material would be best to use in the etch, and second dose any one know what the radius of the cab roof is as the drawing dose not show it but it dose state midland and caledonien gauge on the follow lines of the roof. don't know if that helps. Link to post Share on other sites More sharing options...
AJ427 Posted March 13, 2014 Share Posted March 13, 2014 I have found this to be very useful and universal advice on etching: http://www.hollywoodfoundry.com/Docs/Metal%20Etching%20Principles%20and%20Rules.pdf Link to post Share on other sites More sharing options...
Gt.Shefford Posted March 14, 2014 Share Posted March 14, 2014 I would go for 10thou (0.2mm) - its what I have usd for the 08-16 roof etch (can't help with the roof radii) If your using PPD don't forget that they require 6 layers on the drawing - half etch front outline, half etch front solid hatch, half etch back outline, half etch back solid hatch, not etched outline, not etched solid hatch. Jonathan Link to post Share on other sites More sharing options...
RMweb Gold farren Posted April 19, 2014 Author RMweb Gold Share Posted April 19, 2014 thank you for all the advice above i have had to put the 2300 class on hold for know as i can't find the rad for the roof may have to just copy the Hornby one in the end. but in the mean time i have some questions on how to get a drawing into a useable etch drawing i under stand the colours but and can swop between layers on AUTOCAD but do i just copy the drawing and then change the line colours how do i infill the lines to one colours. hopefully no back etching will be needed which should cut down some of the steps also the scale needs to be taken down to 84% here a pic the ends should be down in the next day or so, i think what i am saying if how do i move forward from this Link to post Share on other sites More sharing options...
Gt.Shefford Posted April 19, 2014 Share Posted April 19, 2014 The reduce the scale use scale by reference https://www.youtube.com/watch?v=kwyrtrVjEX8 To infill between the lines you need to use the HATCH tool - to the left of the Arc, bottom icon on the draw panel. select solid hatch. Jonathan Link to post Share on other sites More sharing options...
RMweb Gold farren Posted April 20, 2014 Author RMweb Gold Share Posted April 20, 2014 hi jonathan thanks for the pointers that has help have had a play but not saved anything yet as i don't want to mess anything up i question is what colour do i do the door out lines when they go through half and un etched parts of the drawing Link to post Share on other sites More sharing options...
RMweb Gold farren Posted April 22, 2014 Author RMweb Gold Share Posted April 22, 2014 i have been playing around with the in fill and have so far got the to br sides to in fill with out any gaps just the other two to do. but a question is size i ask on my other page about resizing and was told 84% was the figure to resize the drawing to get a 3/16 drawing to 4MM i tried this but when i measured it on screen it was too small so i had a guess and after some playing around for .905 brought the overall size to 266mm which works out as 66'6" which is right. but when i printed it out it came out under size by a lot. would this just be to fit the paper as i am using the student version which put a border round the outside all the time. or should i have stuck with 84% Link to post Share on other sites More sharing options...
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