Drawing Patterns

[Charlie10]

I draw a lot of parts from flat patterns that I get from our guys in the shop to cut out on the table. Doing it manually with a tape, protractor, calipers, etc. can be rather time consuming if you're working with a complex pattern. I'm just curious if anyone has found any better methods for this or how you may do it.
My experience - I've found that parts that are small enough, it works great to put it on the document scanner and import it and trace around it. Larger patterns I've plotted on the table with the laser pointer sight, but I've found the reliability/ accuracy of that to be marginal. It's ok for getting approximate shapes. I've also taken pictures of patterns and imported and scaled to trace around, but if the pattern is not laying completely flat or your camera is not completely level, it is easily distorted. I know there are 2D inspection tables out there too, but I can't justify 50k on one.

[djreiswig]

If you are drawing it with a tape measure and a protractor, try using a cad program. Download the free version of DraftSight.

[Gamelord]

I would recommend Corel Draw. Use the "Guidelines" to lay out your pattern, then "Snap To Guidelines' to draw your shape. Super simple to do. You should be able to draw up a complex 2D drawing in minutes (If you have all the dimensions).

I included a link to a simple video that shows how to use guidelines to create a perspective, but hopefully you can see how to use it to draw your shapes.
Also, for precise measurements, drag a guideline from the side or top, then double click on it and it will open up the guideline setup. There you can type in the exact positioning of the guideline for both the horizontal and vertical guidelines. You can also move them, add or delete them from there too.

So, if the shape you are trying to create is 4" tall, top is 22" long and the bottom is 28" long with a slanted side on the right:
I usually start by dragging a horizontal guideline onto the page anywhere, double clicking on it, then moving it to the 0 position, Then type in 4" on the box on top and hit "ADD" (This creates the top and bottom of the shape). Then on the left select "Vertical" I would enter in 0 for the position and click "ADD" (to create the first vertical guideline), Then I would enter in 22", hit "ADD", Then enter in 28" and hit "ADD".

Once done, make sure the "Snap To Guidelines" is selected in the "View" pull down menu.
Then click your freehand drawing tool. Select the guideline intersection at 0,0 and click, move to the top corner, click again to draw the line, click to continue and move to the right top corner at 22", click again to draw the top. Then click to continue and move to the bottom corner at 28" and click to create the diagonal end. Click to continue and move back to the 0.0 position and click to finish the shape.

Here, I would then fill the object with a color to make sure it was fully closed. If so, export to DXF and sent it to your table to cut.

There ya go. I just drew a rectangular shape with an angled end to exact dimensions without the use of a single ruler, protractor or pencil.
I timed myself drawing this and it took me 1 minute, 8 seconds from start to finish.

I have included the original Corel Draw file if you want to open it up and play with it to see how it was done.

Video: https://youtu.be/o468N8fbNEM

[SegoMan DeSigns]

X2 on CD the step and repeat function will make patterns a breeze.

[djreiswig]

I can draw these 4 lines in a lot less than a minute in DraftSight. Turn Ortho on. Draw a 28" line horizontal, then a 4" vertical, then a 22" horizontal, then a line down to the start point and you're done. No guidelines needed. Easy peasy.

[acourtjester]

I echo the above about learning a CAD program, you can find free or inexpensive ones (or expensive if you like) but do get one. There are many tutorials on YouTube for different ones, they all work similar. I started about 6 years ago (70 years old) not having any experience CAD or CAM. I now have built a few tables and can draw my own parts for Plasma, Routing, and 3-D printing. The main differences are what each program call operations, or the Icons they use. Once you learn how to draw a few boxes and modify them it starts to make sense, and it becomes easier as you expand into more complex projects.

[SeanP]

Not sure Charlie is talking about drawing by hand, sounds to me like he is drawing in cad but transferring the measurements from his flat patterns by hand.
It's something I get a lot of as well, I'm in the same boat as well, some parts are a right pain to measure up and prone to mistakes!

I do find the camera fairly good if you don't need to be super accurate, if its a small part less than a foot say I would use the phone but even then keep back and use the zoom keeping as square on as possible.
For bigger parts I use a better camera and again keep back and zoom in.

I do have scananything from sheetcam its ok, bit slow and drawing needs a lot of cleanup in fact I usually redraw on top of scanned dxf, maybe I'm doing something wrong I haven't had a lot of time with it.

[Tautog13]

You haven’t mentioned how large a pattern..... but if in the range of 24”x36” (Arch “D” sheet) or 36”x48” (Arch “E” sheet)
You could lay your patterns (I am assuming sheet metal?) on to one of the above typical size sheets of paper and physically trace w/pencil or fine tipped pen and take it to a print shop and have it scanned to .pdf/.tiff/.png & have them email it to you.
Obviously you would still have to import the same file into your cad program to trace, but it would be quite accurate to what the physical pattern is.
You should be able to purchase the Arch D or E size sheets from the same print shop to have them on hand.

[Charlie10]

Sean got the idea, perhaps I should've been more clear. I am drawing everything in Solidworks. A CAD program is not the issue. You have to actually get dimensions by some means to draw it up though. When you're working with sometimes irregular shaped patterns that someone cut out by hand, it can be tricky making it accurate. Yes I have had a little success with the camera method Sean, but if you don't get everything perfectly level and flat you end up tracing a distorted picture and your part is a little off.
Tautog it's various patterns/ sizes. If it fits on our 11x17 scanner here, I scan the pattern directly then trace around it in Solidworks. That works great. The problem is when you have a pattern that is larger than that. Not a bad idea on the print shop in some cases, but taking it to the nearest shop that is a half hour away (if they're capable) every time I need to draw something isn't usually practical.
Without expensive inspection or scanning equipment this just might be the reality of the process. I just thought I'd check if anyone had come up with anything I didn't know of or hadn't thought of.

[Tautog13]

Tautog it's various patterns/sizes. If it fits on our 11x17 scanner here, I scan the pattern directly then trace around it in Solidworks. That works great. The problem is when you have a pattern that is larger than that.............. I just thought I'd check if anyone had come up with anything I didn't know of or hadn't thought of.

I can only further suggest taping together enough 11x17 sheets of paper for you’re larger patterns and making witness marks on the sheets where they join/align. Trace your pattern......remove/cut tape holding the sheets together and scan the individual 11x17 sheets in the flatbed scanner.
Assemble the scanned sheets in your CAD program referencing the witness marks and group them.
Trace as you normally would.
Sounds more complex/time consuming than it probably would be....but has potential to be quicker and more accurate .

[Charlie10]

That does sound rather time intensive, but may be helpful in some cases. Thanks for the suggestion.

[Billythegoat]

if it fits on to my computer monitor I hold it up to it and trace it there. If it's small enough.

[Rdwfab]

I have been eyeballing Logic Trace for a while now. Not sure how accurate you need to be or how accurate the Logic Trace would be but it’s very interesting for this type stuff. I spend quite a bit of time on this same thing.
Haven’t been able to let go of the $$ for one but it’d be ok with me if you try it out and let us know!



http://www.logicgroup.com/LogicTraceCncDxf.html

[Charlie10]

I'm sure it would be ok with you haha. The one I would want would be about $8k looks like, a little pricey. I would be a little concerned about the accuracy because anything you trace is never quite true to size, just because of the offset of the pen/ pencil, but it certainly would get you close. It does look like a very interesting option. I have checked them out before.

[rikduk]

Hello, here's how i draw unusual shaped plates of various sizes using CAD (Draftsight)

-I place a L shaped square flat on the floor, so that the corner is on the lower left corner from my point of view.
-I then place the part flat on the floor, just touching each side of the square.
-I then measure and draw using coordinates for each beginning and end of line segments, hole centers, and if you pick
a few points along a curve, its pretty easy to then draw it in cad.
ex: if i have a diagonal line, i measure and draw the beginning and end of this line, according to the square
ex: X: 5.125 Y: 8.062 to X: 15.625 Y: 9.5

You can do this even for a huge part, just place 2 straight edges at 90 degrees

Richard