PASSTIME HOBBIES

INSTRUCTIONS IN USING YOUR CAD
SYSTEM FOR MAKING LASER CUT PARTS

by William Kaminsky

Revised November, 2007

Contents:

1. INTRODUCTION, AND SOME THOUGHTS AND COSTS

2. BEGIN YOUR PROJECT BY SETTING UP YOUR FILE SYSTEM

3. BEGIN THE PROCESS

4. PRIOR TO DEVELOPMENT OF PARTS, WE NEED TO DO A FEW THINGS SUCH AS .....

5. DEVELOPMENT OF PARTS

6. USE OF AIDES: SCANNERS AND GRAPHIC SOFTWARE

7. USE OF AIDES: DIGITIZING TABLET

8. USE OF AIDES: AIRFOIL PROGRAMS

9. PLOPPING THOSE PARTS ON TO LASER CUTTING SHEETS

INTRODUCTION, AND SOME THOUGHTS AND COSTS

The flood of low cost computer-aided-drafting (i.e. CAD) programs on to the computer market has brought thought into the head of a modeler with an average ability for drafting to create and design his own model kit. Certainly we all know, it will be of equal or better quality model kit than the time tested die cut or printed sheets many of us have gotten so used to. The creation of your own set of parts hinges upon your experience with presently available laser-cut kits, your ability to comprehend those old high school quality drafting class lessons, and as an end result put all these visions together. Buying a computer and a CAD system will not instantly make a parts draftsman out of you, nor many times even a competent draftsman. You need to acquire and develop that missing quality of plan reading, controlling factors, layouts, inventory, tolerances, real cost, production and placement, and a host of other items which need to be addressed by the individual before and along the way after he assumes the project at hand. Thinking back, it was quite easy to pencil on a line to a sheet of vellum and then lay in another an inch away and parallel. But how do you tell the computer to do this? The writer has been in the hand and automated drafting field for more than he'd like to remember, and as such still learns a short-cut on occasion in the process. Herewith, I'd like to pass information on to readers on what is up in creating their first laser cut kit. The kit, which of course, will become the envy of all who have set eyes upon it at first appearance.

To begin the project you first are going to have to lean upon the experiences of others who preceeded you. This is not an inexpensive activity, and that first project will at minimum cost you a few hundred dollars. A catch phrase or hint here and there will stop some of that ricocheting from recklessness to overcompensating. Others have done this in the past, and it is not new. In short, your first design should be a copy of what has already been flown and tested, not something off the deep end. The simplest laser cut project is to take and replicate a die cut kit, or something from plans made by another designer in which all the specially shaped parts have been laid out. The advantage of replicating and old die cut kit as you will soon find out is that an inventory of parts, placement of individual parts on sheets, and the accessories have all been figured out for you in advance. It is just a simple re-draw exercise of dozens of little drawings. Much like assignments in a school textbook where you pulled out a perforated page, did the work and handed it in. In doing the replication of a long out of production kit, an advantage will be in having parts "in hand" as compared to on the plan. If there is a discrepancy between part and plan, I tend to lean towards the part as being the correct fit and the plans as the correct intention. But, don't take my word on this, as so often in the past, there are times in which the plans have been known to be better than the parts.

Before things get too far along here, what ought to be brought out within this initially is not to read through all this, and then rush out an buy something because you read it here. Likewise, hopefully you didn't buy something and herein trust to find all the magical answers as to why it didn't work like the advertisement or salesman said it should. If you don't already have available to you any of the items noted herein, begin first with a demo, then ask for a reference as to yet another user. Find out about his abilities, and match them to yours. If he is a dummy and you are not, then perhaps you may need something a bit quicker and with more abilities. Then, if he is rich and you are not, buy the best you can afford and still get the value.

There is no substitute for training. If you did not complete a high school quality hand drafting course, take one. This information will do you no good unless the basic skills are known. The use of pencils, triangles, circle templates, and how to manipulate each item is directly related to computer drafting. When I lay an old plan upon my drafting table, I begin with sliding around those plastic aides to figure out how the original draughtsman designed the plans, what controls its dimensions, and what was his intent. Then you can begin the installation of his information into your project. Many times you are going to cuss out that old timer, as your work will be so much more accurate than his, however remember too that his work once flew, and yours has yet to. You need to have a feel along the process as to when to doubt his work, and rely on yours. It is inevitable that it will happen, as when the plan calls out for a stick of wood to be 3/16" by 1/4" and it don't measure that off his plans.

To begin here, just what CAD program is best? A so often asked question, and I will be purposely evasive. I have used multi-user engineering programs which cost hundreds of thousands of dollars to set up, and then I have used those $3 floppy disk quality programs that you find at a computer swap meet. Just because your computer set you back a grand, doesn't mean the software cost can't hit you even harder. The costs as to a system and its compatibility between you, the computer, and the end user (the laser cutting firm) can only be best judged by yourself. When you hand over that final computer disk to the foreman of the firm, his computer won't question if it came off a 486 obtained at a swap meet for $35 plus $10 for the monitor and $5 for the one disk CAD program. It only understands properly formed and accurate drawings. That system once may have been state-of-the-art a decade or two ago, and is the butt of jokes today, but it only matters the quality of your efforts instead of the brand of computer.

The terms used in creation of drawings by a particular CAD program will doubtfully match what you have experience with. Certain CAD programs out there on the market are designed around the talents of architects and the terms or examples in the manual are developed in that direction. If you have to look into the Index of the manual every 3 minutes for how to create a polyline, alter its elements and attributes, and then can't find that term noted, you bought the wrong system for yourself. Same here is if the new CAD system only runs a strange printer/plotter and you don't have it. It may cost you an additional couple of hundred dollars just to see if your work is any good. If it runs only in DOS 6.2 and you presently have Windows XP loaded onto your computer, you may not be able to communicate with yourself, nor anyone else.

Whatever program you decide to first buy, first do a bit of investigation. It must be able to export information so that the laser cutting firm can translate your file information in the minimum of time and without a bunch of afternoon telephone instructions. That is the system for you. The buzz terms here are familiarity, compatibility and interchangeability. They are very important and must be remembered before you get going.

FAMILIARITY

I just bought Wa-zoo CAD. I want to construct a series of circles to a certain radius. I look in the back of the manual for "circle" and it isn't listed. There is a term called "loop" and it can only be done to certain fractional radaii. I wanted something a bit more adjustable, who can I talk to in order to resolve this constant annoyance? Is there anyone else locally who has experience in doing this?

COMPATIBILITY

I just bought Wa-zoo CAD. In the set-up box it mentions that it is fully compatible with most any dot matrix printer. I have an ink-jet model which I have used for two years now, and it runs fine on everything else. There is a whole section in the back of the manual as to how to set up for a certain printer, which I do not have, how to alter or add a line to the AUTOEXEC.BAT file, and I can't find in the index just what this is, and my computer help file don't know either. Then, just where do I find one of these older printers and why doesn't the software support my model of equipment? It didn't mention anything special on the outside of the box.

INTERCHANGEABILITY

I just bought Wa-zoo CAD. Upon completion of my drawings, the software saves it in Wa-zoo format. All the drawing files contain a WZ extension, and there is no way to save it in a format in which any other non-Wa-zoo CAD computer user can read my files. Now that the work is done, can the laser cutting firm or even a friend read my files? Some of the earlier versions of TurboCAD put out a drawing file with an extension of TC2 which could not be read by any other software except that by another I.M.S.I. user, same as for DesignCAD with their DC2 format.

It costs less than a whole computer system, but that first telephone call is costly too. If the new software box has a Whoop-de-doo as to compatibility with other systems, and your laser cutter doesn't interchange with that, don't lay out another dollar or create another line until you two have the ability to. You have to investigate compatibility besides the initial costs to do your project. When contacting that laser cutting firm, ask them just what computer drafting programs formats they can interchange with. Some firms listed in the telephone book can only read CAD/CAM industry disks like G-Code or I.G.E.S. (International Graphic Exchange Standards). Your simple disk may cost them $100 in time or set up fees to convert it in to a readable format. So now Mr. Foreman, if there is an error in any of my parts, and I want to make a few changes before cutting again, do I get hit up for another set-up charge? Your set-up fees total to more than I paid for the software.You will read of a few other discouraging dollar figures further into this that may cause you to reconsider the whole process.

There are a few low cost, fast, and popular laser cutting machines now on the market and being sold nationwide for various applications, besides cutting model airplane kits. One manufacturer has designed his machine around the device drivers within Autocad Release 10, yet another around CorelDraw, and yet another around Rhinoworks. Release 10 is a computer program which hasn't been marketed since the 1980's. Not too many persons today have this program loaded into their computer, nor can find the interchange disk once available to convert or backgrade the Release 11 and 12 drawings. Rhino and CorelDraw although popular in certain drawing circles are exceptions to the basic CAD systems we are familiar with and have used for more than a decade. The resulting work done with these softwares is very nice, and unless that copy of the project disk will work in the foreman's computer, you won't have access to his low cost option. You will have to search out for a firm who can handle your file format. And remember, after hanging up the telephone and muttering "why doesn't he upgrade to a more modern software", it is often difficult to change the mind of a seventy year old man who has something which works OK for him and his customers. It is YOU who has to investigate and conform before proceeding on the project if you intend to take advantage of his services.

As an example, in the Los Angeles area there are about 75 firms offering laser cutting services in the yellow pages. Most all are set up for industrial cutting of high quantity sheets of metal or wood. When you find that individual firm who will take on your small time project on a prototype basis, ask a few of the above noted questions, beside cost per unit, set-up charges, interface conversion costs, etc. Will his computer system accept a Wha-zoo CAD file or not? Even though you haven't proceeded very far, mail him a disk with anything representing a drawable file on it. If he can convert it, then you are in. Continue on with the remaining questions on your mind. Also now with the age of the internet, you may be able to send files to a multiple of places via e:mail attachment, get a speedy answer and save a dollar also.

To help matters along in your software choice, there can always be some incompatibility between one version of popular software and a later upgrade. It is called upgrades, revisions or current release. 'Oft times, a newer version will not be downward (or older) compatible. Your older work will upgrade, but after it gets used a few times it aquires the attributes of the latest version, and thus may not work again within the computer it was originally designed upon. This is especially notible with AutoCAD. Work done in Release 14 will not work in a computer running Release 12. It will go uphill OK, but not downhill too well, if at all. If the laser cutting firm is using some software based upon Release 10 or Release 12, don't plan on mailing the foreman a disk done in Autocad 2002. There are options within AutoCAD Release 14 which will permit you to SAVE-AS an earlier release format, however you need to be familiar with what is translated out upon conversion. You can get faced with running two versions of the same brand of software on one computer just to make sure of compatibility. How you sort out these items is up to you, but in general for now go with the flow in your choices. It can be cheaper to purchase obsolete software if the laser cutting firm is local to you and perhaps can save you dollars in their hourly rate. If you get lost as to compatibility, ask the person who gave the recommendation how he solved the situation.

As Autocad by Autodesk is probably the most easily recognized name in computer aided drafting software, its terms, capabilities and abilities will be used and referenced many times within this. Not to say that other software of lesser or higher cost better fit the reader, but moreover the datum for the industry at present is AutoCAD by Autodesk, much the same as Microsoft and Windows are for computer operating systems. Autocad 2004 has been retailing near $3700, which is often more expensive than the complete home computer system. The introductory price of their older versions probably exceeded the purchase price of your first computer. I have only come upon a couple non-Autodesk softwares as of this writing which state they are close to 100% file compatible to certain popular formats of Autocad (even Autodesk states it is not) and they have been retailing in the less than $400 range. They are professional programs which use most all the terms and commands that Autocad uses, plus have import and export filters to earlier versions.

When purchasing that CAD program, much the same as with word processing or spreadsheet computer programs, the average button puncher will be using basically up to 20 commands over and over again. He will use yet another five to ten options maybe once per drawing session. He will seldom use the extra 100 options available. That new CAD software does need to have a couple of capabilities, or you are in for long and difficult drawing sessions. One, it needs to have the ability to INSERT a small drawing (which was created and stored in another location on the hard drive) into the drawing you presently have on the screen. This term may be referred to as CUT and PASTE in your setup. It enables RIB6 to be set into another unrelated drawing, and more than once in the same drawing. If your present CAD software will not enable you to do this, look for another brand. That simple, and that necessary.

Two, it may be a luxury, but a similar CAD command that enables you to XREF (or cross-reference) to other drawings will really stop you from making errors down the line in your project. This is sort of a modern feature (developed ten years ago) of which will be explained later, but for now ask the saleman if or not the CAD software has this capability. If the box you are looking at inside the computer store does not state so in exact words, and the computer store salesman gives you an I-Dunno, then thank him, and contact the manufacturer directly and ask the question. I have found a real popular CAD software program with the modelers does not have either of these capabilities. It generally is a big point in the creation of parts and as such in whatever terminology the vendor calls it, the box will label if or not it can be done.

A big personal thing to consider with the purchase of any CAD program is to look for a large viewable screen area. The vendors like to clutter the area with command buttons that I seldom, if ever will use while working within the program. My first few years in creating plans and parts were spent using an old 386/12 with a 14 inch monitor. It took 2 seconds to zoom in on a part, as compared to 2/10ths of a second today. The output quality is still 100% compatible today. You still have to stop and think a bit before going on to creating the next line for any part, so speed isn't everything.

As you read further along in this, I will get into a few optional software programs, and a few of the hardware items which you will need or ought to be familiar with. The point being, is that a late model Multi-media, 850Mhz, 256RAM, 42GB hard drive, 16Meg graphics accelerator, 56K modem, and with a 17 inch monitor can certainly run Wa-Zoo CAD and get the job done alright. An old 486 with 8 Meg RAM and a 14 inch monitor that you bought at the local swapmeet for $50 which runs an earlier and simplier version of some popular software can also meet your needs. They both put out the same quality of files, and hopefully the end user (the laser cutting firm) will be able to read each just as quickly. In a few instances, the earlier version files will be preferred, as those later versions contain a host of line attributes that the laser cutting firm has to interpret. This complicates a normally simple file exchange. Keep it simple.

Lastly, once you begin creating parts, it will become evident that you want to have a few options to speed things also and get onto an even footing with the big boys. Here is where you need to contact your friend, the salesman or the techical section at the vendor. Ask them if it will support or expand into a few of the areas noted further at this site which you may not have thought about. Imagine purchasing a new car and asking the salesman if it will parallel park easily, and getting back a responce that "No one parallel parks anymore"

Next section: SETTING UP YOUR FILE SYSTEM