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Sketchup STL/DXF import dimension problems

Posted by CraigRK 
Sketchup STL/DXF import dimension problems
June 21, 2010 02:42AM
Hi all,

I want to print out dimensioned drawings of some of the 3-d parts in the Mendel set. I thought a simple way of doing this would be to import the .stl into Sketchup and then add dimensions.

I have no problems importing either the STL or the DXF (the example is the Mendel Vertex). The problem is however that it comes up as around 24500 mm long. This is obviously wrong. The same happens whether I import the STL or the DXF.

Does anyone know what I am doing wrong?

Thanks,
Craig
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 03:16AM
The STL file format doesn't know the concept of measurement units. You have to tell the receiving application the STL is meant to be in millimeters. If you can't, simply shrink the parts by a factor of 25.4 .


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 03:22AM
Markus,

Thanks for the quick reply. I didn't know about STL being measurement unit agnostic. I guess I need to find a part for which I accurately know one of the measurements and then work out the factor. As even dividing by 25.4 as you suggest, the vertex piece still comes out at c. 1000mm long (I took the longest dimension). I would that this part is no more than 100mm at the most.

Do you know why the DXF import does the same? Is it also agnostic to the measurement units?

Thanks,
Craig
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 03:37AM
Craig,

If you're planning on machining or woodworking a Mendel, I'd suggest making a WolfStrap instead:
[reprap.org]

Smaller fastener count, less material processing, etc. And drop-dead sexy. grinning smiley

Regarding files, did you try these:
[reprap.org]


-Sebastien, RepRap.org library gnome.

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything! grinning smiley
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 03:45AM
DXF knows what a unit is, so it's a question of what the STL -> DXF converter does. Another option is to use the STEP files found at [reprap.svn.sourceforge.net] , i.e. [reprap.svn.sourceforge.net] ?


Edit fixed the link.

Edited 1 time(s). Last edit at 06/21/2010 03:46AM by Traumflug.


Generation 7 Electronics Teacup Firmware RepRap DIY
     
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 10:58AM
Sebastien,

Going off topic for this list (3d software), but I guess I probably will end up going this way as it is much simpler.

One of my other plans is a CNC mill anyway so the experience will stand me in good stead (although I don't expect to re-use any of the parts).

I have a fantastic pre-made z-axis from a computer monitor stand. It uses 2 'drawer slides' and has a gravity/weight conpensating mechanism, but only gives about 90mm travel as opposed to the Mendel spec of 140mm. Do you think this will be a problem? It will save me a little effort. I also happen to have two sets of larger slides from an scrapped flatpack filing cabinet.

Looks like the way to go.....


----------------------------------------------------------------------------------------------------
ABS, PLA Pellets and Masterbatch available for UK and Europe:
Suitable for use with Filastruder and similar filament extruders

[www.emakershop.com]
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 10:59AM
Markus,

Thanks I will experiment further and also look into STEP. Regardless of where I go with my RepStrap I want to resolve this issue.

Thanks,
Craig


----------------------------------------------------------------------------------------------------
ABS, PLA Pellets and Masterbatch available for UK and Europe:
Suitable for use with Filastruder and similar filament extruders

[www.emakershop.com]
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 01:06PM
but only gives about 90mm travel as opposed to the Mendel spec of 140mm. Do you think this will be a problem?

Welllll, depends on the size of the stuff you're printing. smiling smiley
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 01:09PM
SebastienBailard Wrote:
-------------------------------------------------------
> but only gives about 90mm travel as opposed to the
> Mendel spec of 140mm. Do you think this will be a
> problem?
>
> Welllll, depends on the size of the stuff you're
> printing. smiling smiley

Duh, I should have made myself clearer :-). Do you think it will be a problem for a RepStrap, i.e for printing any of the Mendel parts?

As indicated by the reason for this post in the first place, I don't have a good handle on how large the Mendel parts are, so don't know the size of RepStrap needed.
Re: Sketchup STL/DXF import dimension problems
June 21, 2010 01:39PM
The tallest Mendel part is only about 35mm high (x-carriage-lower).


[www.hydraraptor.blogspot.com]
Re: Sketchup STL/DXF import dimension problems
June 22, 2010 02:42AM
nophead Wrote:
-------------------------------------------------------
> The tallest Mendel part is only about 35mm high
> (x-carriage-lower).

Thanks Nophead. I guessed it would be enough, so I have gone ahead with my RepStrap last night. I'll be blogging about it and will post in the appropriate forum later.


----------------------------------------------------------------------------------------------------
ABS, PLA Pellets and Masterbatch available for UK and Europe:
Suitable for use with Filastruder and similar filament extruders

[www.emakershop.com]
Re: Sketchup STL/DXF import dimension problems
June 22, 2010 03:20AM
Duh, I should have made myself clearer :-). Do you think it will be a problem for a RepStrap, i.e for printing any of the Mendel parts?

Sorry, I was being a twit. eye rolling smiley

If you're up for a research project, once you're up and printing, you can always have your machine self-bootstrap by printing its own upgrades; go from a screw-drive to a belt drive, etc. etc. This may be more fun/work than printing a Mendel.

Edited 1 time(s). Last edit at 06/22/2010 03:20AM by SebastienBailard.


-Sebastien, RepRap.org library gnome.

Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything! grinning smiley
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