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Bruce Griffing
10-15-2003, 11:50 PM
Most of what I do in the shop requires a 2-d drawing with dimensions. I am not into CNC, solid modeling, 3d rendering, etc for my home shop. I tried several programs and they were all overkill for what I do. BTW it is easy to try them as most will give you a one month demo version. Recently I tried Delta CAD (no personal connection). It does just what I need to do. Makes great drawings, is easy to use and cheap. I paid $40 for the program and $5 for shipping. Well worth it in my opinion.

Uman
10-16-2003, 12:17 AM
Once you go 3D modeler you will never want to draw in 2D again. The capability of actually seeing your minds eye on the computer monitor, rotating, sectional, assembly, and explode, will absolutely astound you. 3D CAD software automatically produces 2D drawings and some 3D CAD software is easy to learn. I use Alibre Design; it cost about $600 and is well worth it. Consider CAD software an expense like you would a new machine. It is difficult to accept this expense, but it will catapult your capabilities to enormously. 3D CAD is a virtual Machine shop that allows you to test your design before you spend time, material and hopes. Also it allows you to share your minds eye view your peers. Try 3D CAD for a month free and see what CAD technology has to offer.
Jeff in Florida

Evan
10-16-2003, 12:40 AM
Bruce,

3D is the way to go. I couldn't have built my telescope without 3D rendering to check my calculations and the resulting fit. Zoom in at any point, look real close or see the whole picture.

Example:

http://vts.bc.ca/astrophoto/scope_a.jpg

dvideo
10-16-2003, 01:15 AM
If you are learning and qualify for a student discount, 3D CAD can be quite affordable. Solidworks and Cadkey are two I use a lot now.

-- jerry

MikeHenry
10-16-2003, 12:45 PM
I'll second Uman/Scott's reply. I bought Alibre about 5 months ago and found it very easy to learn. I've done a couple of projects since then that would have taken far longer with my previous CAD tool (Visio).

For some reason I never could get comfortable with the standard 2-D CAD programs, but Alibre just seemed to click with me.

Mike, near Chicago

Bruce Griffing
10-16-2003, 01:29 PM
My question for you 3d guys is this - how much time do you spend in your shops versus the time in front of the computer? I would never argue against a well planned project and I believe in having good drawings to work from but I don't want to spend most of my time on project design. Maybe it has to do with the complexity of what I do versus you 3d guys. Dunno.

Evan
10-16-2003, 04:16 PM
Bruce,

For simple projects I work out of my head. Sometimes I make a couple of loose sketches on a bit of paper. For even fairly complex projects I often only have a few basic sketches either in the computer or on paper. BUT, for the telescope project I couldn't have done it with out modeling it first. It involved some fancy math footwork with trig and modeling it the first time found a clearance problem with all the rod ends that would not have showed up until assembly of all the made pieces. I spent perhaps 100 hours on the computer model and it was worth every minute.

MikeHenry
10-17-2003, 03:40 AM
Bruce,

I'm still pretty green at the 3D stuff and have no formal CAD training.

That said, the time spent drawing and machining a project is strongly dependent on the project, as you might expect. On a recent siingle part I spent about 1/2 hour on the design and drawing and probably 1 hour machining it.

A more recent project has about 400 parts total with about 20 unique parts. I spent about 50 hours on the design. This was sent out for machining by a commercial shop and judging from the cost they charged about the same number of hours - would have taken me at least 200 hours to make it.

As Evan said, one of the major benefits to 3-D design is that you can view assemblies or sub-assemblies to see how everything fits together.

Another is that most of these 3-D modelers (SolidWorks, Inventor, Alibre, etc.) are parametric, which means that you can use dimensions from one part or feature as inputs for another part or feature. For example, for a cylinder you can specify that the OD and wall thickness and then have the program calculate the cylinder bore as the OD - 2 x wall thickness. If you then decide to change either the OD or wall thickness, the program will automatically update the ID in the part design and the 2-D drawing. That's a trivial example, but this feature can really grow on you in a hurry once you start to use it.

Another benefit is that you can replicate features on a part (patterning in Alibre). An example here might be designing a cylinder bore for a multi-cylinder engine. Once the first bore is designed you can easily insert the remaining bores with a few mouse clicks. If you later decide to change the bore dimensions or features, the replicated parts are automatically updated.

Mike, near Chicago

Techtchr
10-19-2003, 08:45 AM
I use and teach Inventor. If you can get a student copy of any of these programs by taking a community college class, you will be able to get it considerably cheaper than buying outright. PLTW also offers a sudent version, but it is restricted to students taking the class and is not upgradeable.

3D modeling is easy to do basic shapes and produce the orthographic drawings, as well as assemble multiple parts. Doing more complex stuff takes just a little more time. In an hour of sitting with you and showing you the program (assuming you know basics like right click and left click...) and the XYZ coordinate system. I could have you drawing stuff that you thought you could never do. Its that easy. I had my 3rd grade nephew drawing models in about a 1/2 hour of showing him.

I still like 2d for some things. Sometimes I have the design in my head, and all I need is a 2d sketch to help me remember the numbers. Also doing cnc programs for pockets and contours is sometimes easier with a 2D drawing.

Matt

Techtchr
10-19-2003, 08:54 AM
Bruce,
I just looked at your profile to see how far you were from me, in case I could help you out one on one. All I can say is I won't be driving down to see you. I've visited your state twice, and Damn its big. I also want to say due to your occupation it will probably take you a little longer to learn 3D CAD than my nephew. http://bbs.homeshopmachinist.net//smile.gif Just kidding. It otta be a piece of cake. There are PLTW schools in your state. You probably can get someone to help you there wit a little searching.
Matt

John Stevenson
10-19-2003, 10:02 AM
There are some short cuts to CAD drawing as regards cost.
First off for 2D work Turbocad does a free earlier version downloadable from their web site. A bit naff but I thought I'd mention it.

The unlimited version of Intellicad2000 has been removed from their site but a copy still exists on an Australian university site.
Sorry I don't have the URL handy.

Dolphin also do a free copy of their cad program available for download from http://www.dolphin.gb.com

Now onto 3D.
Solid Edge in the UK differs from the US site in what is on offer and pricing.
the UK site at http://wwwsolid-edge.co.uk offers some software that the US doesn't.
or a start there is the free Solid edge layout program which is 2D only and there is a copy of the full 3D program for £50 UKP but you have to be registed at a UK college.
If you have friends in the UK this can easily be achieved.
I can't offer to do this as I have done it already and I'm on file.
What I can say is from filling the form out on a Wednesday and paying by CC to getting the full package with manual on the Saturday they couldn't have done much checking.

Another alternate is to see if you can get a copy of their earlier UK release called Origin. This is a full 2D/3D package but is limited to only doing one 3D model, no assembly and no savable 3D section in CAD.
I think thy dropped a goolie wuth this one as it was too good and they quickly withdrew this and replaced it by the Layout program.
Upside is it was a free issue and they can't take that back.

John S.

Bruce Griffing
10-19-2003, 05:23 PM
Thanks for all the replys. I was surprised that nobody came down on the side of a simple 2d cad program. So I was motivated to look a little further. The prices for outright purchase of most of these packages is prohibitive for the home shop user. I looked at Inventor - more than 5k. So if I am going to take a more serious look I will have to take one of the back door approaches suggested by several of you.

John Stevenson
10-19-2003, 05:44 PM
Bruce,
95% of my work is 2D and I can't see that changing. What it basically boils down to is any drawing I make come off the bottom line. I make parts, not sell fancy drawings.
True a nice 3D drawing looks better but who pays for it?
Often it's better to do a simple drawing and make the part. If there is any conflict in design it's probably far quicker to alter the design than spend many hours doing a 3D drawing to spot the error.
I have had drawing thru from Solid works that were wrong so it's still down to the operator and if he's not the guy turning the handles then anything can happen.

Another point is that often a one off or prototype design needs altering on build anyway, regardless of how good the drawings are. If you can keep simple you have more scope to alter than if you are constrained by complex drawings.
As an example if you look at
http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/new%20pointer1.jpg
this is a pencil sharpener that sharpens 12,000 pencils per hour. It's unique in how it works and was the first one of this type made.
Other than a side view to get the general layout for the belts and the pattern was machined from this same drawing for the side castings nothing else was drawn up. This was all in my head and parts were made to fit each other.
I have no idea how many alterations were made. You could say many but as there were no drawings to mod you could say it went together perfectly http://bbs.homeshopmachinist.net//biggrin.gif

On test we had a little hopper feeding trouble but that was soon cleared up. After that we test ran it and did about 100,000 pencils [ anyone want any pencils - they didn't want them back http://bbs.homeshopmachinist.net//biggrin.gif ]then we stripped it, cleaned it and THEN took drawings.

John S.

Evan
10-20-2003, 12:29 AM
John,

Sorry, but in my telescope design I spent many hours working out the angles of the truss rods. When I modeled it I put in the numbers and then looked at the 3D rendering to see where the parts ended up. I discovered that the rod ends were too close together.

This is the cool part. I calculate the angles on a piece of paper, write it into the program and it spits out a picture that shows how the parts fit. I discovered that the parts didn't fit. Recalculate, render again, and the parts fit, now I can build it.

uute
10-20-2003, 12:59 AM
Hey John,

That Gatling Gun pencil sharpener is pretty "sharp"! ; )

I assume it was for a pencil manufacturer to sell sharpened pencils -- or did it go to the Chinese Space Program?

uute

John Stevenson
10-20-2003, 05:00 AM
Evan, Yes it's cool but I couldn't justify 100 hours to do this. A hundred hours is 2 1/2 weeks manufacturing time.

uute,
Normal pencil sharpeners and mostly they are German work, work by rolling the pencil down a shaped ramp at 1/2 the angle of the point, along a linishing belt.
These are fast and can go up to 24,000 pencils per hour, they also cost about $35,000.

In this case the pencils are special in that they are all plastic. Plastic compound mixed with graphite extruded in a continious length is then coated by the coloured outside coating.
When cool it's snapped to length, trimmed and sharpened.
This is all part of the green ecology, recyclable brigade, save the whales, get a full set.

Down side is they can't be sharpened on a belt sander as they melt with friction.
They have to be sharpened by rotating knives and no one has built a rotating knife machine since the 1900's as they aren't as fast as the belt sander models.

John S.

dvideo
10-20-2003, 10:43 AM
FYI the pencils....

Is there a good group of deserving schools there? More importantly, is there perhaps a good way to donate pencils to students directly? Might be a good use and a write off too....

--jr