CAD for raw beginners?

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John_S
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Re: CAD for raw beginners?

Post by John_S » Sat Nov 04, 2017 9:21 pm

2nd'ing Draftsight. Free and easy to use. I've used it for years at home and use it at work every day -- Prefer it to Solidworks at the office because it's not as cumbersome.

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BAdams
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Re: CAD for raw beginners?

Post by BAdams » Sun Nov 05, 2017 12:10 pm


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Marty_Knox
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Re: CAD for raw beginners?

Post by Marty_Knox » Sun Nov 05, 2017 4:24 pm

Am I the only one who thinks you should take an old fashioned. pencil on paper, mechanical drawing/drafting class before you try to learn CAD?
Most of the CAD drawings I get are cluttered with too much information, yet often leave out important dimensions.

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Builder01
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Re: CAD for raw beginners?

Post by Builder01 » Sun Nov 05, 2017 5:10 pm

Indeed, everything I design starts as a sketch on paper drawn with pencil. I make a few dimensions where necessary, and then make the part. Many things never get a drawing or sketch at all. I read about folks that spend tremendous a mounts of time with CAD and never actually build anything. I only use CAD when I really want to document something neatly and clearly and possibly to pass on the drawing to others.

I hope this is the intention of the original poster.

The Van Brocklin pumps re-drawn by Bill Shields is a good example of something done in CAD in order to pass on the information to others. A tremendous amount of time, I'm sure, was taken to do this, but worth the effort. If you just need to make parts, a sketch will do fine. If you are building a locomotive, don't waste time.

David

Tharper
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Re: CAD for raw beginners?

Post by Tharper » Sun Nov 05, 2017 9:33 pm

Marty_Knox wrote:Am I the only one who thinks you should take an old fashioned. pencil on paper, mechanical drawing/drafting class before you try to learn CAD?
Most of the CAD drawings I get are cluttered with too much information, yet often leave out important dimensions.

Hello Marty, to a certain extent I agree with you. I teach a drafting & engineering technology course at the high school level and I can tell you that we do some board work but not much. I was trained as a traditional draftsman and spent many years on the boards - ink on mylar, linen, etc. dragging a drafting machine across the board all day.

In the time it would take me to teach them proper hand lettering skills they can work-up through creating acceptable (key word - "acceptable") shop drawings using CAD. Its not so much that CAD is the problem - but applying proper drafting standards. Getting students to adhere to proper drafting standards in regards to dimensions is the toughest part. (learning the program is usually the least of my worries!) With that said...I find that though modeling parts etc. in 3D is cool and the renderings are incredible as well as the ability to verify function, fit, strength etc. all within the programs, they tend to loose sight of the fact that the 2D shop drawings are THE most important product. Without proper dimensions, notes sections, details etc. the part simply cannot be built. This problem applies to board drafting as well. I also struggle with getting them to use only enough views to illustrate the geometry of the part. In other words their tendency is to show 3D views of everything - even a simple straight shaft! Or all six possible views when only the front and top might do.

One assignment I give my students is re-master older drawings using modern modeling and CAD technology. Examples have included a set of drawings of a Stanley 20hp steam engine which we donated to the Stanley museum, a 1901 Robert's 3HP Marine engine (MIT contemplated using our drawings and models to build a working prototype), a Bentley rotary engine, the Falk locomotive, etc. Such projects are a wonderful way to teach how important adequate dimensions, sections details etc. are. I cannot tell you how many times a frustrated student will ask me how they are expected to create a part with missing dimensions - it really drives it home!

One advantage to us is the fact we can create parts that are ready for the CNC machine or our 3D printers. A recent example is a unique magneto coupling we reverse engineered. Using, a handful of wasted away parts (the engine was found underground in a gold mine) and the patent drawings we modeled the pieces, created the shop drawings, 3D printed a mock-up to show the client and are now using our CNC milling machine to mill out patterns which will soon be on the way to the foundry. Another such project was a set of patterns & core boxes for valve shrouds for a Wisconsin engine in a 1918 FWD truck. If we didn't have CAD these projects would be way beyond the capabilities of my students - many of whom will be going onto college for Mechanical engineering.

We are always looking for interesting projects and ideas!

Best regards,

Terry
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Harold_V
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Re: CAD for raw beginners?

Post by Harold_V » Mon Nov 06, 2017 12:34 am

Thanks, Terry. That needed to be said.

H
Wise people talk because they have something to say. Fools talk because they have to say something.

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SteveHGraham
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Re: CAD for raw beginners?

Post by SteveHGraham » Mon Nov 06, 2017 11:58 am

Keith Fenner uses a pencil. He held up one of his drawings in a video and referred to it as CAD: "Cartoon Assisted Design."
Every hard-fried egg began life sunny-side up.

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Marty_Knox
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Re: CAD for raw beginners?

Post by Marty_Knox » Mon Nov 06, 2017 12:48 pm

Tharper wrote: In the time it would take me to teach them proper hand lettering skills they can work-up through creating acceptable (key word - "acceptable") shop drawings using CAD. Its not so much that CAD is the problem - but applying proper drafting standards. Getting students to adhere to proper drafting standards in regards to dimensions is the toughest part. (learning the program is usually the least of my worries!) With that said...I find that though modeling parts etc. in 3D is cool and the renderings are incredible as well as the ability to verify function, fit, strength etc. all within the programs, they tend to loose sight of the fact that the 2D shop drawings are THE most important product. Without proper dimensions, notes sections, details etc. the part simply cannot be built. This problem applies to board drafting as well. I also struggle with getting them to use only enough views to illustrate the geometry of the part. In other words their tendency is to show 3D views of everything - even a simple straight shaft! Or all six possible views when only the front and top might do.

One assignment I give my students is re-master older drawings using modern modeling and CAD technology. Examples have included a set of drawings of a Stanley 20hp steam engine which we donated to the Stanley museum, a 1901 Robert's 3HP Marine engine (MIT contemplated using our drawings and models to build a working prototype), a Bentley rotary engine, the Falk locomotive, etc. Such projects are a wonderful way to teach how important adequate dimensions, sections details etc. are. I cannot tell you how many times a frustrated student will ask me how they are expected to create a part with missing dimensions - it really drives it home!
Thank You for your post, Terry. You brought up the points I was trying to make.

Kimball McGinley
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Re: CAD for raw beginners?

Post by Kimball McGinley » Mon Nov 06, 2017 3:36 pm

Thanks everyone for the suggestions, I will pass them along.

By the way, my friend and I are both senior mechanical engineers and hold many patents. He just got moved to management before CAD really came in, whereas I resisted going to management. I work in Solidworks daily. When I showed him some brake shoes I had laser cut from 1/2 steel, he saw how they would fit his hobby of custom motorcycles, but he does not know CAD. Yet...

I also agree with Marty and "Tharper", and in fact, I am working on a course like his for the new engineers at my company. Some may recall I posted on here for simple engine plans a few months ago...

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DianneB
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Re: CAD for raw beginners?

Post by DianneB » Mon Nov 06, 2017 4:38 pm

I started with pen/paper drafting in college, engineering technology, and used it for decades, until the advent of the PC and AutoCAD. The first personal project I did in CAD was my 1/2 scale traction engine, drawing every part in 3 views (1995/96) and building parts or patterns from the drawings. Thanks to accurate drawings, the whole machine went together without a hitch.

When I no longer had access to free AutoCAD, I switched to proge CAD 97 because it was free and AutoCAD compatible and still use it. I like to be able to create 3 views of each part, make each view a 'block' and then fit them together in assemblies to check fit and clearances - so much easier than doing it on paper!

RET
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Re: CAD for raw beginners?

Post by RET » Mon Nov 06, 2017 7:16 pm

Hi,

I started off a long time ago (in High School) drawing with pencil and ink with drawing pens on paper so yes, you could say that I am "old school" but now I much prefer CAD. Some CAD programs are better than others, but just make sure that the one you use can make true drawings & not just a "pretty picture." I remember one Autosketch program I used at work that did just that, it gave a "picture" that wasn't really accurate. I'm sure that program is long gone now, but be sure you pick one that is both accurate and easy to use. Also, whatever you pick is probably what you are going to have and use for a long time, so do your research well.

I use Anvil1000 which is 2D and DOS based but its like having an infinite sized piece of paper. It works the same way you would on a drawing board and is incredibly accurate. The program shows eight decimal places and keeps track of twelve. I also use Synergy for the times I need 3D capability.

I like CAD because of its accuracy and because I can call up dimensions on the drawing that I didn't tell it in the first place when I was making the drawing. Some times two views are all that is necessary (side or top and end), usually 3 are sufficient, but sometimes the odd extra one is needed. Just use the views that are necessary to describe the part, but make sure that all the dimensions are there that are needed if you are going to make what ever it is. Also remember, it is quite possible to draw a part that can't be made, or something that would be only possible with very specialized equipment.

In this regard, most of us have enough practical experience that we won't fall into that trap, especially since we are likely making the drawing for our own use with the equipment we have. For some parts I don't even make a sketch, for others I may make an assembly or even a proper drawing which I can use to get line intersection coordinates that I need to use in the "G" code for the little CNC mill. What I do depends on what I need.

Just my thoughts on the subject.

Richard Trounce.

mspetersen
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Re: CAD for raw beginners?

Post by mspetersen » Mon Nov 06, 2017 10:41 pm

I'd also recommend Fusion360. Not only free to Hobbyists (vs $300/year subscription) but there are quite a few sources of instruction on YouTube. One source is http://academy.titansofcnc.com will walk you through several Fusion360 tutorials from drawing, the CAM process and finally machining.
Mark Petersen

12" x 36" Logan Lathe
Lagun FTV-3 Mill

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