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Measuring up components to CAD
rcx718 - 13/3/15 at 01:57 PM

Hello!

I've read so much useful info on this forum, it's invaluable. This is my first post though. I've started my first custom car build. I've done lots of mods and fabrication in the past but never a complete vehicle.

My main question for now is if anyone has any tricks or tips for measuring up my components for my CAD drawings, ie getting the measurement of my axles, engine, transmission etc so I can model it all off CAD. Tape measure only goes so far when angles and shapes get more complicated.

I have access to a FARO arm at work which is an electronic arm that gives 3D co-ordinate read out of the position of it's tip, but the arm is on a granite table so I can't put big heavy items on there. And it's at work so I can't over use it either.

Mostly my engine, transmission, transfer box I want to get into CAD.


HowardB - 13/3/15 at 02:53 PM

look into the online libraries, many have specific models that have taken hundreds of hours to compile, these can be downloaded and used.

I use grabcad for solidworks models,...

hth


dhutch - 13/3/15 at 04:11 PM

I was going to say, its a fair slice of work, and i two would start of by googling things like '3d model, ford english axle' in the hope of finding at a parasolid of step file of the dam thing.

You only want the outlines and mounting points, but even that would take a while!



Daniel


rcx718 - 13/3/15 at 05:18 PM

Yep it's the position of the mounting points that are most important. The rest can be drawn up as a box for all I care.


bi22le - 13/3/15 at 08:03 PM

List ypur exact components on here. If they are common some one on here may of already collated them.


rcx718 - 15/3/15 at 07:05 AM

The drivetrain will be based on the Suzuki SJ because it's very light. To be honest I can probably manage to take measurements from the drivetrain and axles. The main issue might be the engine, and at the moment I'm just going round in circles trying to figure out an engine to put in.

[Edited on 15/3/15 by rcx718]


Sam_68 - 15/3/15 at 09:32 AM

If you're determined to have an accurate model of the components, these days you can 3D scan components, and there are companies who will do this for you for a reasonable cost. You can buy hand-held scanners, and even get Apps for the iPhone that will do it (though the output results I've seen are pretty coarse and low-resolution).

The basic output is a 'point cloud' though (as the name suggests, a 3-dimensional 'cloud' of data points defining the scanned surfaces). The computer processing needed to turn the point cloud into a surface mesh or virtual solid can be more costly/time consuming.

HOWEVER:

Personally I'd suggest that you need to avoid falling into the 'virtual car' trap of modelling your design in too much detail. People these days seem to think that just because it's possible to photo-realistically model every last nut, bolt and washer, that it's actually necessary to do so.

Drawings are a means to an end, not an end in themselves.

You need to establish enough detail to make sure that everything fits and that your suspension geometry is accurate. A simple rectangular box is usually adequate for the engine (measure and fabricate the mounts afterwards, in situ), and 'stick models' of the uprights with ball-joint centres.

A quick mock-up of the engine bay or transmission tunnel/engine bay in MDF or Celotex insulation board will allow a trial fit, much quicker than CAD modelling every last detail on an engine/gearbox. It will also will tell you things that CAD will never tell you about how easy it is to physically manipulate the components into place for assembly, and what clearance you have around them for subsequent maintenance.


Volvorsport - 15/3/15 at 11:40 AM

Yeah, we use a laser scanner at work, its so accurate that when we come to fitting the product it only fits the one we've measured...!


rcx718 - 16/3/15 at 10:54 AM

Some good tips here. So you say there's some scanners and apps? I wouldn't mind trying them, any brands that I could look at?

Don't worry I'm not the sort to over design, it gets boring and pointless beyond a certain point.


Sam_68 - 16/3/15 at 06:06 PM

quote:
Originally posted by rcx718
So you say there's some scanners and apps? I wouldn't mind trying them, any brands that I could look at?



Just Google '3D scanners' or 'iPhone 3D scanning apps'.


dhutch - 16/3/15 at 06:35 PM

quote:
Originally posted by Sam_68
Personally I'd suggest that you need to avoid falling into the 'virtual car' trap of modelling your design in too much detail. People these days seem to think that just because it's possible to photo-realistically model every last nut, bolt and washer, that it's actually necessary to do so.

Fully agree with this, especially for a one off or v.low production car.

I would take measurements of the mounting points, exhaust and inlet posts, overall dimensions, etc. with the Faro arm, bang the points in an model the engine as a cube for the block, cube for the head, with short lugs coming out for the mounting points, done.


Daniel