How do I accurately transfer CAD drawing to sheet of wood?

[Woody2Shoes]

Hi,

My 2d's worth: last time I used AutoCAD was quite a few years ago - I seem to remember it had quite good facilities for printing out a full-size drawing on multiple sheets (which could then be taped together pretty accurately and pinned through or traced).

Looking at your drawing, I'd be tempted to ignore electronic aids and draw the thing out using basic geometry (compasses, ruler, set square) on the board itself.

Cheers, W2S

 

[lurker]

Hi,

My 2d's worth: last time I used AutoCAD was quite a few years ago - I seem to remember it had quite good facilities for printing out a full-size drawing on multiple sheets (which could then be taped together pretty accurately and pinned through or traced).

Looking at your drawing, I'd be tempted to ignore electronic aids and draw the thing out using basic geometry (compasses, ruler, set square) on the board itself.

Cheers, W2S

Agree.
Looks like a 10 minute job to me.
............plus another 10 minutes to triple check.
If you really want to go mad you could get the CAD to calculate the corner to corner diagonals as a check.

 

[novocaine]

set your base line on the factory edge and use a T-square (you can make your own that will be well within tolerance) use the T square as a storystick, mark every Y measurement on it.
make one end of your baseline the furthest point to the left, the other end the furthest to the right, mark each change in direction, slide your T square and mark the point, you've only got 7 points you need to mark on the X axis and 7 points on the Y, as long as all measurements are from the same base point (don't measure from the last point) you should be well within tolerance.
why go to all the trouble of dividing the points when using one point you can work all the rest out. join the dots and you'll be within 1mm and no fancy tools have been used. if you haven't got a T square stand the board up and use a plumb line, but really a 90 square is pretty easy to make.
once that one is cut, use it as a master, trim close to the line then use a router and follower to get it perfect, only points you'll need to clean up are the inside corners.

I think this is pretty much what has been said already, but with a T square, something that a drafy used all the time back in the days of fullscale drawings.

 

[haggis999]

I hope you are asking about creating a single template, rather than attempting to mark up multiple of these patterns independently. Even if the master template isn't 'perfect' at least the multiple supports would then be the same.

But to you question, I'd never use a protractor - they can't hope to get any more accurate than 1 degree. if its right angles, then a compass (home made will do - mark lengths on a strip of wood). + use of Pythagoras will do the job. If you want other angles then you can still use the home made compass, but you will need to use some basic trig (cos/sin/tan).
Its been 30+ years since my maths degree, but I can help on that score if you PM me.

I also studied maths at university many years ago, as part of my electrical engineering degree, though my trigonometrical skills are now very rusty after a career in IT management. I'm also not an experienced woodworker, hence my request for some practical guidance.

I was indeed planning to mark up each shelf independently. Because I can't print larger than A2 and don't possess any larger paper, creating a single master template could only be done by sticking several sheets together, which I fear might just be the source of new problems (though I might still give it a try, especially if I find that AutoCAD LT offers a facility for printing on multiple sheets).

My current hope is that careful marking of co-ordinates will provide the easiest solution. As previously mentioned, I may also try printing a large paper protractor using http://www.ossmann.com/protractor/. If those methods fail, I will resort to trigonometry, as you suggest.

 

[novocaine]

make 1, use that as the master. as said above. it's what follower router cutters are fore.

don't mark out the angles, you can't be repeatable which is as important as accuracy here.

 

[lurker]

Am I right in thinking this is a shelf and two sides will fit against a wall ?

 

[haggis999]

Am I right in thinking this is a shelf and two sides will fit against a wall ?

Yes, these are shelves, but on a straight section of wall, not a corner. The side with the rectangular notch is the one adjacent to the wall.

 

[haggis999]

make 1, use that as the master. as said above. it's what follower router cutters are fore.

don't mark out the angles, you can't be repeatable which is as important as accuracy here.

Please pardon my ignorance, but what is a follower router cutter? A quick Google search didn't offer much clarification.

After marking the required outline, my intention had been to clamp a straight piece of wood on top of the shelf at a measured distance parallel to one of the lines to act as a guide for the router. Obviously, I would need to reposition this guide for each cut. Holes would be drilled at the two internal corners before routing.

Is there a better method?

 

[novocaine]

yes. make 1, use this in your router.

http://www.screwfix.com/p/erbauer-pro-f ... -4mm/74505

repeatability is king. you only need to mark out 1 then. which is what people above are trying to tell you.

edit to add, you dont need to drill the holes, let the router do the work. all you have to do is cut the blanks somewhere near then attach the master (the first one you made) and trim it to match with the router.

 

[MrTeroo]

How about using an agency to print one out for you?

http://www.plotgiant.co.uk/

 

[haggis999]

yes. make 1, use this in your router.

http://www.screwfix.com/p/erbauer-pro-f ... -4mm/74505

repeatability is king. you only need to mark out 1 then. which is what people above are trying to tell you.

edit to add, you dont need to drill the holes, let the router do the work. all you have to do is cut the blanks somewhere near then attach the master (the first one you made) and trim it to match with the router.

I must admit that I had wondered if there was a way to carefully make one master shelf and then make exact copies with a router. Now I know the answer. Many thanks for that useful information!

 

[Racers]

Your angles are easily marked out with a compass eg 150=180-30 deg so with a compass and ruler you will be able to mark it out.

Pete

 

[haggis999]

How about using an agency to print one out for you?

http://www.plotgiant.co.uk/

I thought this morning that it might be worth contacting a local printer, but haven't had the time yet to check that out. Your link provides another option at an acceptable price, so thanks for that.

 

[Sheffield Tony]

You could at least ditch the protracter and use a large square with 60,30 and 90 degree angles, which would get you 120 and 150 degrees probably more accurately. Though the compass / trammels is probably a better way.

 

[novocaine]

ahhhhhh, you don't need to measure the angles, why is everyone trying to draw it like you would on a piece of paper. you need to mark the points and connect the dots, that can be done with one 90 degree square (as we would have done it on a drawing board once upon a time if scaling an existing drawing), the angles are all a result from the points marked.

anything else is over complicating it. you don't need to print it out full size either, you wouldn't do that if you were building a house.

you use the bottom left corner as 0,0. you measure 723 along the edge of a fresh sheet and mark it, that is your baseline. all other points are inside that line. now you mark off the points along that line, first the lower left corner of your drawing (which you haven't got the dimension for on that drawing, it should be there if you want to make this), then you mark off the points of the cutout on the bottom line (again now dimension) then you mark of the upper point (Again no dimension) then you mark off the bottom right hand corner (you have the dimension from the bottom left corner but not from 0,0 at the moment) thats all the X points.
now you use your square, from 0,0 you measure up to the first point and mark it, move to your second mark and do the same, then the third, fourth etc. once all your points are marked you connect the dots. the angles have to be right assuming you've put all the marks in the right place.

accuracy comes from using 1 point for all measurements and 1 angle of 90 degrees.

either I'm not explaining how to do this very well or people aren't used to working with the concept of coordinates anymore.

you need to dimension your drawing correctly for a start. there should be 6 dimensions across the bottom 6 dimensions on 1 side.

 

[haggis999]

I'm certainly convinced that using co-ordinates offers what appears to be the best solution, though that will have to wait until I've finished cutting the grass (I answer to a higher power, and her commands are not to be ignored).

My only remaining interest in a full sized print is as a double check that all is well.

 

[haggis999]

Given that I only joined this forum a matter of 7 hours ago, I must record my appreciation for all the assistance that has been provided. I was only trying to seek guidance on a fairly minor problem, but thought it worth checking that I wasn't missing obvious solutions due to my lack of experience in woodworking. The result has been several very useful tips, for which I am very grateful.

David

 

[Jacob]

.....
How did builders and architects lay out complex buildings, back in the day?

BugBear

Full size with dividers, chalk lines, scribed lines, etc etc. There are reports of full size layouts scribed on temple and cathedral floors. Much the same technology as used in boat yards, steel fabrications, quite recently, until the advent of the computer.
A piece of string is the basic divider - can be folded into 2, 3, 4 etc and can also draw circles and ellipses. Precision work done with hinged dividers.
Not sure what the OPs problem is. Maybe it's down to trying to use Autocad for working up an extremely simple design?
Pencil, straight edge, full size rod, a lot easier.
PS a router is not a good tool for cutting up plywood. The design itself, using Autocad, cutting with a router; obviously making a very simple job much too complicated!

 

[Racers]

This is a useful technique http://www.diy-wood-boat.com/spiling.html

You could have made a patten straight from the corner with out involving a computer.

Pete

 

[haggis999]

Not sure what the OPs problem is. Maybe it's down to trying to use Autocad for working up an extremely simple design?
Pencil, straight edge, full size rod, a lot easier.
PS a router is not a good tool for cutting up plywood. The design itself, using Autocad, cutting with a router; obviously making a very simple job much too complicated!

There was far more to designing the exact shape of these shelves than is obvious from the end result I have presented here. AutoCAD LT proved to be an excellent tool for my purposes, especially as I already had this software and knew how to use it.

You've told me that a router is not a good tool for cutting plywood, but you omitted to tell me what would be better! I've already made it clear that I'm not an experienced woodworker, so feel free to point me in the right direction.