Mechanical Drafting questionssssss.

[ieezitin]

Driver.

You have made some valid observations. all are to be true.

Just sitting at the board with rules and the pencil and watching the drawing of the piece come to life while all the time your brain is filtering through thoughts of design and function is really making your brain work harder. Your point on how the cad system is functioning and how it interrupts this process is so true.

The poster of this thread is I believe a young man, trying to acquire new skills and knowledge, if he learns the art of drafting done by hand and absorbs the techniques in this field, cad would be a walk in the park to him. This way he will have two strings in his bow.

All the best. Anthony.

 

[mu38&Bg#]

If you aren't familiar with the CAD software you are using, enough that running the system is a challenge itself, then it may interfere. I have been running CAD for over 15 years and can say that it has never created a design worse than what I could have done on paper. It is certainly many times faster. The trouble I have is that it becomes so easy to try to optimize a design with CAD that I could have often machined a functional but not optimum part by the time I explore the various options for the design in CAD. Of course there are CAD programs that are only digital paper and there are mechanical engineering design software.

 

[hobby]

Thankyou Izeetin,
Very encouraging post,
lot of good info. you gave..

I'm not building a drafting table, but a portable straight edge drawing board I see advertized.

I know I will eventually buy one of those portable drawingboard, with builtin parrallel straightredge.

But your idea of making a nice project of it, has got me thinking,

More on that later.

However here is the way I use my cad program,
and what I would like to acomplish doing it the classic way.

I have a concept of what mechanical devise I want to build.

Then I begin drawing to chosen dimensions, the parts I would need for that part of the build.
From there I begin moving these parts in place, and rearranging for best fits, and clearances, and what have you.

I then place the hardware in the drawing and move them for best fits, clearances....

Once I have enough done to start the actual machining process, I click at key points, on the parts, to find actual dimensions, of where to drill the hloles, how big of a bore I can make, and length of certain parts ect.ect...

I come up with the design, and my CAD tells me what the dimensions are to machine too.

But I don't want to have to continuously rely on a CAD program, to be able to get my working designs,
People will compliment me of the nice mechanical designs, how it all works so smoothly, and the first thing I say, (after thankyou), is I could never get this kind of project working this well if it weren't for my turbo cad program... It's the true designer, it tells me what dimensions to machine too, bla bla bla....

So that's why I think I would like to be able to do projects the classic way of drawing design work,

I got my CAD in the 90's, before that in the 80's all my woodworking projects, were drawn out with a triangle and ruler,(in place of a T-square), remembering my highschool days of drafting class, 1980.

I remember drawing isometric views, and the orthographic views, and figuring the cut sheet to aquire the best possible material yield.

Even the depth of cuts needed and all dimensions were CALCULATED.
Math was the only way known, and was NOT any daunting task.

That's the same time when I never knew about cordless screwdrivers, being popular in a home shop,
ALL of my screws were driven by a cordless screwdriver, but this cordless screwdriver NEVER needed recharging, I could afford a bunch of these cordless tools and not spend a penny on batteries.

AND, THIS was not an overwhelming daunting task to put handreds of screws in for joining wood, parts together. Never considered it being too much work. Had no other choice.

One more tangent:

I got one of those electronics workbench circuit simulators.
Well after that I hardly picked up a real component, all my electronics projects were virtual.

After these simulators got way too expensive for the home hobbyist, I decided any time I build a transistor circuit, it will be ALL calculator, paper and pencil, schematics, and ALL math formulas, to design and build a circuit, and all real components, and all real testr instruments.

NOW, I no longer need the dictatorship of a simulator to design a circuit from scratch, I have a much better understanding of why, and why not certain circuits work. The learning, doing hands on is superior, to any simulator. Now I use a simulator to test quick 'what if scenarios', (mainly for conveniance) rather than a design crutch...
End of tangent-----------------------

I haven't gone that far overboard, with my CAD, but so I don't go that far, is why I am learning to design precision projects using the good old calculator and pencil and paper method.

Now izeetin,
back to your good idea of making a nice table...

Since I am going to get a portable drawing board sometime, I am going to look on the innernet at some pictures of furniture drafting tables, and make a miniature working model, and combine the enjoyment of machining and woodworking together for a fun model engineering project......

But this time I will buy a $10.00 drafting set from the art store, and do it all by classic drawing again, like I used to do.

Thanks everyone again for all the help you have given me...

 

[Tin Falcon]

harbor freight of all places has drafting machines new for under $50
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=1815&xcamp=google&utm_source=googlebase&utm_medium=cpc&zmam=33951326&zmas=12&zmac=112&zmap=1815
Tin

 

[hobby]

Thankyou Tin.

I never thought about looking there...

I think I might look into that,
and while I'm using it to draw with, I could take measurements, and see how it works,
and if not too imposible, I still would like to make a small scale model of a drafting table, with a hopefully working, drafting machine.

It wouldn't be a very overwhelming ambitious first time project to get my feet wet learning the curve of drawing precision parts, without using CAD.

This would be for me a model engineering project...

It's funny how not relying on CAD, is so difficult, when you used it all the time.

BUT, Before this project, I still have about a 1/4 of the way to go on my engine project.

Need to machine the hole in the blocks to hold the push rod tubes for the exhaust rockers, then machine the push rod tubes and push rods, and get at least one cylinder ready to fire up (air pressure), just to see if it will work or not...

Still a ways to go yet.
I like to take my time and do a little at a time.

Thanks again for the heads up, on the drafting machine...

 

[Tin Falcon]

Hobby:
A ggod book on mechanical drawing is also a good Idea There are many old text books about to be had cheap. A college book sale can be a gold mine for old tech books. And there are several on the internet archives and Google books.
I would also incourage you to learn free hand drawing.
Drawing on the right side of the Brain by Betty Edwards . Again plentiful and can be had for a few bucks.
Tin

 

[RollaJohn]

The Harbor Freight link above doesn't work. Try this http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=1815

 

[hobby]

Hi, everyone,

This is what I just purchased.

Something portable enough for me to get the most use of it in my small workshop.

http://www.draftingsteals.com/20262.html

Thanks for all the advise, I will look into getting book material as I progress in this,
for now I want to use what I have learned using my computer, and apply it to hand drawing and calculations.

Thanks...

 

[Tin Falcon]

hobby the drafting shield pencil pointer and drafting brussh are also essentials as are stick erasers these can be picked up as school supplies.
Tin

 

[CrewCab]

Blimey .......... this takes me back a few years ........ ......... I've got a similar drawing board (complete with stand in my loft somewhere) ......

I spent 20 years as a Draughtsman before my career took a different direction, and since then I have used CAD, but I have a lot of time invested in a drawing board ...... ask away if I can help I will be happy to do so ..... 8)

1) Get a good adjustable set square, check it at 90o in both directions
2) 0.5mm Pentel type pencils are great
3) try 2H / 3H leads for drawing ........... softer will just smudge the whole drawing, harder and you will cut the paper ......... HB is for doodling on a pad and working out problems ......... buy lot's of HB leads and lot's of paper ;D
4) For now (and for a while) avoid the temptation to draw in ink, you will spend forever putting things right.
5) Have fun

Hope this helps

CC

 

[Brian Rupnow]

Up untill I got into "computer world" about 12 or 13 years ago, I did all my drafting on a big old industrial drafting board about 48" x 60" long, fully adjustable, spring counterweighted, with a parallel track "state of the art" dual track drafting machine. I loved it, but the damn thing was HUGE and took up an awfull lot of my office space. I was more or less "forced" to start using a computer by my customers (perception was "If you can't design on a computer, you must not be much good!!!"). I kept the drafting board around for a few years, but mostly it ended up taking up a lot of space, with junk piled on top of it.----So I sold it!!!----And then I discovered something horrible. About 15% of my work consists of "reverse engineering". This means that a customer brings me a finished machine, and pays me to disassemble it and create new mechanical drawings of the machine so it can be reproduced in a machine shop. And trust me, there are some things that simply can't be measured with a tape measure, vernier caliper, or micrometer!!! So---What do you do???---You trace the part onto a piece of heavy cardboard, cut the shape out, then lay the cardboard shape on a large piece of paper, and use a pencil to trace around the shape to get the outline onto the paper. THEN--You tape the paper down on your drafting board, establish where the base line is---and then you start measuring the angles and projected intersections of merging lines, (and arcs, and circles) untill you have enough confirmed geometry to draw a new identical part based on that geometry. TRUST ME---Ya just can't do that on your computer monitor!!!---Brian