Is CAD for Me?

I have followed this thread from day one and contributed what I hoped was an encouraging post. All I hear now as I read on is a constant "swish - thwack, swish - thwack, swish - thwack.." It's the sound of a dead horse being flogged.

John

I made a short video with MoI.

Michael -

I can assure you I've not listed you - or anyone - as "Ignore"!

I'll have a look at that link you cite.

Thanks, Nigel

I was just a little concerned when you wrote:

Sorry Chaps - you've lost me with that abbreviation - MOI?

shortly after I had posted those two links.

MichaelG.

The text I've highlighted above leads me to think that paragraph is aimed at the well-versed user or professional modeller, so some jargon might be necessary.

.

But that paragraph constitutes the majority of the text on the landing-page

... Hence my comment, and my provision of a link to something friendlier, for Nigel's benefit.

MichaelG.

Edited By Michael Gilligan on 21/06/2019 20:58:03

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MOI was totally new to me; but thank you for showing me.

I looked at the links Michael offers. MOI seems really for 3D printing ornamental rather than engineering work. FreeCAD would be the better.

I can use TurboCAD, albeit very basically and roughly but practically; thanks to hundreds of hours of effort.

Indeed I spent this evening starting to design in TurboCAD, a bevel-gearbox for my steam-wagon's brake rigging.

I found the gears, a stock metric pair, on a "come-in-handy-bits" stand at an exhibition. Their actual sizes are not very important. Even an equal pair of bevel wheels isn't easy to measure and draw though! I will need to measure them meshed on improvised stub-axles on an angle-plate and surface-plate; rather like clock-wheel depthing.

The brakes on this thing are right crude, just simple blocks suspended railway-wagon style, and acting directly on the rear wheels' smooth steel tyres. The bevels link the operating-handle's vertical shaft to the horizontal screw-shaft extending to behind the rear axle.

The drawing so far of the two wheels and interposed bearing block, establishes the basic mechanical arrangement. I now need measure the centres, modify the drawing accordingly, then design the box and brake-column around them.

'

BTW I made the differential for the chain-driven, traction-engine pattern, back axle from an old car front-wheel drive unit. I replaced the crown wheel with a machined-out motorcycle sprocket; and annealed the differential wheels themselves for turning, in a wood-burning stove overnight.

Where did you get that idea from?

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Not difficult, but you do need a good understanding of gear design, like this:

And after machining on a CNC mill:

Andrew

Also not to hard to model a reasonable visual representation even if you don't want or need the exact profile

Blowlamp -

I had that idea from the sites referred to above. The publishers like to show their software's maximum capabilities. Whilst I understand that, I find it a bit off-putting even though I know the artwork is by the publisher's professional designers pushing the software to its limits.

The packaging for my copy of TurboCAD contains a card advertising the agent (Paul Tracey). He used on it, rather more down-to-Earth, 3D images of assemblies for a miniature locomotive: a 4-wheel bogie in plain view with moderate tinting, a luridly rendered pony-truck, and the boiler manifold in wire-frame view. The last is so "busy" it loses details.

Barrie -

CNC cutting or Printing - either way, my point was I took MOI as primarily for CAM files. However, CNC machining or printing is not available to me; and I need primarily orthographic engineering drawings, with isometric views potentially useful but not so important.

'

Impressive examples you give though. You designed the aircraft parts in MOI, but I take it BobCAD is essentially the machine-tool programmer building tool-paths etc. around the MOI file?

I like that aid to clarity shown in the second screen-shot, by tinting different parts of a wire-frame assembly. I've found colours particularly valuable in an assembly-drawing when I need pick out individuals of repeated components in crowded elevations. If left in one colour, the drawing starts to resemble well-boiled spaghetti.

Recently I completed some structural-geology diagrams in 3D, using colours to differentiate the strata represented geometrically by extrusions. One looked very odd, as if the bed of rock had been mined out of the hill. Then light dawned: to make that layer white and solid, fill its generating shape with white from the colour-chart, not just leave it empty (" white " on the screen).

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I can see that CAD isn't for you. You make assumptions and then wonder why nothing works for you

It's not possible to gain any reasonable overview of MoI from the link you have referred to as it's just there to give a an idea of MoI's capabilities if you have the skill to make use of them. It simply says MoI is easy to use, but is capable of complex things for the more adventurous user.

I did a bevel gear in MoI a while ago.

I must admit I've often wondered how close to each other all these programmes are, behind the trade-marks and patented / copyrighted presentation.

That bevel gear is actually very much like the ones I am using.

To make the assembly work I need join them by a central journal that also prevents the axial thrust on one of them from pushing it out of mesh. I have established the most compact arrangement for that.

This particular gear-drive is not too fussy, but I'd like it to be right both for itself, and experience should I wish to make a more critical version in future.

Techniques for drawing gears accurately (irrespective of draughting method) are described in my text-books. Here though I need know only the pairs' relationship and overall dimensions when meshed. I'm not trying to design the wheels themselves.

I could draw the journal isometrically as it's only a rectangular block with a few cylindrical features, all symmetrical; but I need an orthographic drawing for making it.

'

To those who say CAD's not for me, I want it for me. I want to be able to use CAD sufficiently to support my model-engineering.

Unfortunately I find the CAD publishers' web-sites are very off-putting by suggesting overwhelming complexity and difficulty. That and the lack of any decent literature on the subject, make me feel like, say, a 'celebrity' pop-singer told you can learn to sing from a Wagnerian opera score!

How about these shoes, produced entirely in Fusion.

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" ... from tracing over photos ..."

Via a scanner? I don't know if such software exists, but it could be very useful, being able to translate a scanner file into a CAD one.

'

Re-measured and re-drew my bevel-gears this evening. The measuring was a bit of a faff, but I concocted a way using a small angle-plate and the drilling-machine table; and the new drawing is much closer than my preliminary attempt.

I didn't try to draw the teeth, just the overlapped outlines, in different colours for legibility. I could then add the bearing-block, shaft-ends and thrust collar to hold them together. Drawing the assembly upside down synthesised how I'd measured it, replacing the metal surfaces with the axes, so all the co-ordinate values are positive.

I've still to establish how to make the dimensions work, but I now know how to assemble adjoining drawing entities, in 2D anyway!

Barrie.

Fusion has a facility called Attached Canvas, which allows you to insert images onto any plane or surface you like. Each image can be scaled as needed and used to guide the creation of the model features required. The visibility of attached canvases can be controlled independently, from the model, and from each other. The opacity of any canvas or model can be controlled from almost transparent to fully opaque.

I don't know MOI, but from the video it would appear that organic shapes are created from sets of contour lines defined as splines. Fusion is quite different. It has a facility known as T-splines which allow the direct creation and modification of surfaces in 3D - rather like moulding sheets of clay. That's how the shoes were created. I would like to make it clear that I didn't create the shoes - I'm nowhere near that level of expertise.