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Sketchup- reducing size to 10%


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A couple of years ago I first used Sketchup to design a few 3d printed parts, and had some degree of success until I got stuck whilst designing a loco cab and left it alone for a good while. But earlier this year I decided to have another go and am quite pleased with a small HO scale loco body.

 

One problem I found with it is there are issues where two curved surfaces meet which I think is caused with how Sketchup interprets shapes at this scale, plus of course a problem with not being able to draw radiuses of less than 0.5mm.

 

One way round this I thought was to draw at a 10x scale (ie cm for mm), I tried this with some bogie sideframes but I couldn't reduce to 0.1 of the size without the program crashing, this included two steps of 0.5 then 0.2, etc. and I ended up rescaling them once uploaded to Shapeways.

 

Any suggestions of how to get round this would be appreciated, and whether it is just me doing something wrong...

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when I played round with Sketchup a few years ago i did not think it could do what i wanted so took the plunge buying what was then Alibre, now called Geomagic Design., and although i did not plan resizing initially, i found that with its engineering feel and ability to resize very useful. I do recommend anyone to try packages which are not free for 3D CAD. There was a 15 day free trial for me, and a tutorial package. I am on my second version(new computer), but I am stillonly using the simpler tools. One day i might be more adventurous.

 

Computers crashing, something I get, but when  you are using powerful software then either go for top end range computer or work round it. Even my new computer with windows 10 occasionally throws a wobbly. Mind you I do have other runtime problems so it is as much the operating system. Like motorways when they add new lanes, bigger more powerful computers soon find that extra soon gets used up.

 

When it comes to resizing it normally involves a lot of checking of wall thickness, not too thin to get rejected, not too thick to waste money.

Unless you are only planning to print off items for yourself, then resizing is an essential tool. Someone will always ask if you can resize something, so bettter to be prepared for it. Once I worked out where the changes would be needed, I found it a very quick process.

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Thanks Simon, I really ought to ditch Sketchup but oddly enough I'm still strangely attracted to it. I have asked various knowledgeable designers at shows what they use, I don't think I've had the same answer twice but agree it's worth trialling demo versions and then investing in a full program, as it'll pay for itself in useability and time savings.

 

Something that I think could be better from a beginners point of view is having software that is purposefully designed with a 3d printed product as the end result, instead of an animated cartoon or a kitchen extension. Having something that says "You can't do that" or "Stop including detail that won't be durable enough" would save time and money, and offer a better route into 3d printing.

 

FTR, this is the loco I've done, the red patches are shown as <0.3mm, but printed OK on the prototype:

 

 

post-6819-0-26735600-1476209972.jpg

 

post-6819-0-64611000-1476210063_thumb.jpg

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A couple of years ago I first used Sketchup to design a few 3d printed parts, and had some degree of success until I got stuck whilst designing a loco cab and left it alone for a good while. But earlier this year I decided to have another go and am quite pleased with a small HO scale loco body.

 

One problem I found with it is there are issues where two curved surfaces meet which I think is caused with how Sketchup interprets shapes at this scale, plus of course a problem with not being able to draw radiuses of less than 0.5mm.

 

One way round this I thought was to draw at a 10x scale (ie cm for mm), I tried this with some bogie sideframes but I couldn't reduce to 0.1 of the size without the program crashing, this included two steps of 0.5 then 0.2, etc. and I ended up rescaling them once uploaded to Shapeways.

 

Any suggestions of how to get round this would be appreciated, and whether it is just me doing something wrong...

 

You don't need to reduce size in sketchup at all - just export STLs in centimetres as I do.

 

The problem with complex curves is that the program is storing a co ordinate of start and end points of each segment that makes up a curve accurate to something like 10 decimal places. If you're working at sub millimetre sizes, that gives you only 9 decimal places of accuracy, factoring the drawing up by 10 or 100x gives you more leeway with complex geometry. It only takes something to be rounded up by 0.0000001mm and it throws a drawing into chaos. 

 

I work at 10x model size and use components. If a curve isn't behaving at normal size, I copy it and resize it 20x and repeat the action in the large component, leaving the original size one in place. USually does the trick, for really complicated stuff I've had to resize to 1000x. 

 

Another trick if a drawing starts misbehaving is to copy it all to a new drawing, it shouldn't work but it often does (in sketchup and TurboCAD!).

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When I was starting out, Tom Bell recommended Alibre as a good middle price package. You are talking about £400 for latest version of Geomagic Design , but test version can be tried out for 15 days for free,and apart from time restriction everything is there. Beware though as it can become very addictive. My large catalogue of items is proof of that, and also shows how much can be done. I have versions of some of my designs in over 10 different scales.

Edited by rue_d_etropal
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I'm working in meters (I think, will have to check) on Sketchup then in Netfab I basically rescale it by moving the decimal place a bit so 0.80 on the CAD would become 8.0 thus 8CMs

 

Basically I got it set up so things 'snap' at 0.1mms. If I want to go more accurate which I often do then I just find the centre points so the first one then would give a line that is 1/20th of a mill' and the next centre point would divide the line to 1/40th which is usually as far as I need to take things.

 

I do want to tweak the settings so it will naturally snap at 0.05 of a mill' but currently fear touching them in cass I things up...seeing as what I am doing currently is working.

 

I too have had issues with the odd drawing being a nob and throwing it in a fresh file seems go work. no idea why.

 

The ghing I do not like about sketchup is all the faffing about trying to puncture holes without deleting half the model, then drawing loads of anoying lines to remesh everything, then trying to delete them without things messing up and then the punctured holes having faces reappear again.

 

This aspect of Sketchup truly is shite and a complete time waste that reauires a lot of effort and patience.

Other than that I get on with it great.

Edited by Knuckles
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You don't need to reduce size in sketchup at all - just export STLs in centimetres as I do.

 

 

I do something similar, drawing at 1000 times size in millimetres, then exporting in metres. It quickly becomes apparent if you are a factor out if your 3D printer software is able to preview your exported design on its print bed.

Sketchup doesn't like working with curves less than 0.5mm radius, so iterative scaling down of small items by small factors could cause real problems.

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Using these basic packages is ok for your own limited use, but to really take advantage of what 3D printing can do for the hobby, you do need a package that can resize/rescale your designs. Everyone who has uploaded to Shapeways or similar will have had requests to do the model in another scale. I see models mentioned and think, yes, nice model wrong scale.

 

One possibilityof the proposed group I have mentioned elsewhere, might be ability to get siftware at group rates. Not something I have checked, but it is someting that might be worth while.

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I disagree. Look at what I and others are producing using Sketchup and others. I rescale things in Netfab, another freebee and it takes about 2 seconds to do. No need for one program to do all.

Edited by Knuckles
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Lots of excellect comments so far, and would certainly agree that it becomes addictive. But one of the reasons for creating my own designs is because I haven't had much success in asking other designers to change or resize their own models, and although changing from some scales to others might be fine, changing the loco above from HO to O would use six times the material, and you'd have to adjust wall thicknesses, etc on it.

 

I've downloaded my first plug in for Sketchup so far to round edges and have had a quick play this evening with some good results.

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Using these basic packages is ok for your own limited use, but to really take advantage of what 3D printing can do for the hobby, you do need a package that can resize/rescale your designs. Everyone who has uploaded to Shapeways or similar will have had requests to do the model in another scale. I see models mentioned and think, yes, nice model wrong scale.

 

One possibilityof the proposed group I have mentioned elsewhere, might be ability to get siftware at group rates. Not something I have checked, but it is someting that might be worth while.

 

You don't need anything fancy to change scale, whatever you use you're going to need to spend time making adjustments for wall thickness. If you think about multiple scales from the outset, you can make it reasonably simple to accomodate. 

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Hello 298,

 

Are you still having issues with re-scaling? I faced a similar issue but I've found a solution to it (that's if I've understood your issue correctly). Let me know. I'll PM you with a nice a comprehensive solution. If it works we can put it up here on RMweb for any possible future issues.

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I did start by drawing at 10x, but had resizing issues too. I now draw at full (model) size and any elements that I have issues with I draw larger and resize before importing into the main model. It seems that resizing simpler models works better.

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There are loads of bits of free software out there, some good some bad. For those who want to search themout, install them, tweek their computers etc then fine, but there are a ot of people who just want to install one piece of software and start using it.

when it comes to resizing/rescaling I don't see that much on Shapeways, certainly not as much as Tom and myself. I would suggest a minimum of scales to be looking at would be N scale, TT, HO,1/76, 1/64(S), 1/43, 1/32 and 1/30. That covers the main scales for standard gauge. There are also slight variations of each scale, which is why I included both 1/30 and 1/32 for Gauge One. I start with different scales depending on the model. For my narrow gauge i used 1/35 as I was modelling military theme. For my HO locos and stock I start with 1/43.5 then half it . For buildings Istarted with 1/76 as it was easer for brick size, but for some I have started with 1/10th scale because I measured a real building in cm and easier to use those same numbers as mm.  I prefer to be able to finetune my designs myself rather than leaving it to software. On testing out what the Shapeaways software would suggest for some potential thin walls I was not impressed with the result. It can only do what it thinks is necessary where as I know what I a wanting, but am prepared to compromise in some areas, not others.

 

The software you use is your own choice, but as an ex programmer/analyst I prefer the way software I use works and can be amended easily. It is more like writing, testing and debugging a program. Although I work to 3 decimal places i am not sure if that makes much difference. I always recommend people try something first, and most packages you have to pay for have trial free periods.Just because something suits one person it does not suit everyone. I remember playing round with CAD programs many years ago and just did not find them easy to use, and when I looked ar Sketchup and Blender I saw that same problem, for me anyway.

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I think that is why I tend to coming from a different direction to many on the forum. I have come across so many people over the years in the hobby wh are doing something one way just because that is only way they hae seen demonstrated. Ok when things go OK, but I have come across too many who give up, thinking about taking up another hobby. This is one reason why Ihave(unsuccessfully) tried to get magazines to do something about 3D printing(apart from brief bits and reviews of items incuding my items). 3D printing is magic to most people, but all it is is a lateral modification of conventional printing drawings on paper.

Edited by rue_d_etropal
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  • 2 months later...

 

Someone will always ask if you can resize something, so better to be prepared for it. Once I worked out where the changes would be needed, I found it a very quick process.

 

You're certainly right about that, a different EP loco body arrived yesterday and I hurriedly put together a chassis to check coupling heights, etc. Since it was Christmas I decided to post a photo on a Facebook group, and it took all of 20 minutes to someone to tell me I ought to do it in O (my original is HO), and about another 20 for someone else to tell me exactly how to do it and the part they would be playing in it. 

 

Oddly enough, the same loco already exists as a kit in O and it is still cheaper secondhand at $400+ to use it instead of scaling up my design, when I informed the masses of this the answers were that someone didn't have that kind of money and therefore I should only make select bits available expecially for him, or I should print one and use it as a pattern to replicate in resin. Professional manufacturers must be really thick skinned or deaf- I can't remember any of them having this problem, even when Hornby had a separate can from their new 87 in a larger scale there was no question that it was just for show and not going to be a future release....

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I have had sort of reply when asked to up scale. It is easier on the pocket  to down scale. My contention is number of people who design some lovely models for OO, but I want them in HO for my project. I also model in OO , but rarely do anything 3D printed apart from buildings. I do offer OO versions though.

I tend to design at a larger scale, then down size the model. That usually takes care of any small dimensional errors. O scale is an aukward scale to market for,because like OO it has plenty of traditional suppliers, and prices are very competitive. It does not cost me anything to resize a model, just my time and money I spent on software which can do the job .

Basically the very least I xpect from anyone designing for 3D printing is to try to do versions in different scales when asked. It should not take long, and the hobby will thank you. If you don't, and it is a model I want, and I can find scale drawings, I will do it myself.

It is not uncommon to find someone scratchbuilding a model because it is not availabe r2r, then the following year a r2r model is announced. This is the other main reason I have switched to British HO. Chances of any r2r are very slim, and I can offer model in OO as well, no problem. HO works out at about 25% cheaper than OO  for 3D printing, but finding mtoorized chassis can be tricky. I am not looking to dofinescale, but at least I know the ready made track I use is actually to HO , in particular gauge, and I have that satisfaction when somepeople  query my choice of scale. Some are not even aware that the gauge for OO is wrong.

 

When comparing prices, some will point out that a kit is cheaper. My answer is that if they cost in time to build kit, then what is the price. Some designers are tempted to try and add every bit of detail(most people won't notice) and produce parts for loco  chassis , and again it is probably easier for the average modeller to convert a r2r chassis which will work OK. If you are serious about getting people to buy your models, targetting a very small specialist market is not very clever. They will pick over every little detail, and then grumble at the price. If they are skilled enough to scratchbuild the samemodel then they should do that, and if they are not, then they should be prepared to pay the price.

Edited by rue_d_etropal
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  • 10 months later...

It's over a year on from starting this topic, so I thought I'd better post an update. 

 

The prototype loco in Black HDA from Shapeways has been an excellent project, and between other more pressing modelling projects I have updated certain details to the specific locos I'm modelling. I have had to change a few details and now have another print in FUD. Unfortunately the design spec for HDA has changed to a minimum wall thickness of 0.6mm, which has presented a few clearance issues as I was designing for 0.5mm, hence the change of material.

 

post-6819-0-07182500-1510840655_thumb.jpg

 

I've also learnt that I can upload the 10x drawing straight to Shapeways, who then say it's too big and rescale it down, but it is then possible to change the dimensions back to the intended length. I understand the theory and the calculation works (approx 394%), but unfortunately the FUD print is 1mm too short, causing issues with fitting it over the intended chassis block. I'm pretty certain this is a printing error as the resized dimension for the model is spot on what it should be, if so is this to be expected and in your experiences would Shapeways offer a free reprint..?

 

 

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