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

[lebois]

Send the CAD file to a people who do architectural plotting, then plot 1:1 scale. Cost circa £10.

 

[custard]

I don't think there are right or wrong answers to the original question. Factors that might influence the optimum solution would include what equipment/machinery/skills are available, will the plywood be lipped, is it just the three copies mentioned or might there be more, is minimising plywood waste an important objective, and many more questions besides.

None the less, making a few assumptions here's how I'd likely go about the job,

-I'll assume the 485 and 555mm dimensions face out and may be lipped (if it's the 556mm dimension that's the "show edge" then adjust accordingly), therefore I want a really clean cuts on these two edges so will start with oversize ply blanks with these two edges cut on the table saw. In my workshop I might use the scoring blade, I'd certainly check the main blade was sharp.

-I'd then take some 12mm MDF and replicate one of the ply blanks.

-Starting from the 485 and 555mm dimensions I'd draw out on the MDF the pattern with a 0.5mm propelling pencil. I know from experience that I can draw out components of this complexity so that all dimensions are within 0.5mm, that's the standard I'd aim for (it's the standard professional workshops often stipulate). If I didn't get it right first time I'd rub it out and start again, I know it's achievable so I'd just keep plugging way until it was done. If you don't have decent quality compasses in different sizes and other key layout tools then you should buy them, your measuring and layout tools are the backbone of your toolkit and worth digging deep for.

-I'd then cut out the MDF master template, chiseling out the internal corners.

-Check the template, if that's up to standard then you're golden.

-Position the MDF template against the two reference edges on the ply blank, cramp according to the equipment at your disposal, pencil around. Cut the ply blank to slightly over size, i.e. staying on the waste side of the pencil line.

-Reposition and cramp the template, then route out the shape with a copy bit. Again, chisel out the internal corners.

-If there were curves as well as angles I'd spend the few quid to have a bureau print it out full size and transfer directly to templates, fairing the template curves with a spokeshave. For really complex jobs or for long runs (where templates will get damaged or worn out) I may well pay to have the templates CNC'd, then rout template copies from these "master" templates. Most furniture makers I talk to are using CNC (either in house or subbed) less for component production and more for template and jig production.

Good luck!

 

[Jacob]

Send the CAD file to a people who do architectural plotting, then plot 1:1 scale. Cost circa £10.

But you'd still have the problem of transferring it to the wood, and the problem of inaccurate printing (as encountered earlier).

It'd make more sense to give the job to somebody with a pencil who could draw it directly on to the wood e.g. custard above! Wouldn't need a CAD drawing - a dimensioned sketch on the back of an envelope would do.

 

[worn thumbs]

If you own a good rule and straight edge you can dispense with the square.I know the idea gives lots of straight line and square corner woodworkers a dose of the vapours.By using the aligned dimension feature of a CAD system you can determine the distance from the ends of your baseline to any point on the periphery of the object.Where the arcs intersect locates your feature,join them with a pencil line and cut out the shelf from the completed outline.

I just drew the outline of the shelf in Freecad (guess how much it costs!) and took a screenshot ,which I hope will be displayed but its my first attempt at loading an image on this forum.

 

[Woody2Shoes]

I might end up with a router bit that has bearings top and bottom. For copying my master shelf the bottom bearing looks like the one to use, but are there situations where a top bearing offers an advantage?

Yes - those I alluded to in my previous post. Even with ply (as opposed to solid timber), you would be wise to consider the grain direction (primarily that of the the outer plys - especially the outer ply which will be on show) and not try to rout that "uphill" or risk (visible) chipout. This guy does a reasonable explanation of why a top and bottom bearing router is more useful than a single bearing one (top or bottom), given that repositioning the template is definitely something worth avoiding:

https://www.youtube.com/watch?v=EzDWHcqgdbE

Cheers, W2S

PS Here's the expensive Whiteside one I misremembered:

https://www.youtube.com/watch?v=AtTcrCQAnmA
https://www.woodcraft.com/products/whit ... x-1-1-8-cl

PPS the average youtube video does not address router safety concerns - please be sure you know how to protect yourself if you're new to router use!

PPPS A specific advantage of a top-bearing (only) cutter would be if you wanted to do plunge cuts e.g. to rout out a letterbox or a mortice against a template

 

[Steve Maskery]

try googling the words "Joggle stick"

That's very clever, I'd not seen that before. Thank you. But I wish you'd mentioned it a month ago, I've just fitted and alcove cupboard with shelves, all of them anything but square. I did get it good, but it took me a lot of measuring and re-measuring of diagonals and cutouts. It took forever. I'll use one of these next time.

=D> =D>

 

[haggis999]

haggis999

How have you got on so far with cutting out your template?

It has been mentioned how you could cut the internal and external corners but I am not sure anyone has mentioned that you could score the outline before routing the shape, with a bearing guided cutter, in order to reduce the risk of splintering.

Is this the sort of advice that you now need to help finish the job?

At last, a useful post amongst all the irrelevant anti-CAD ranting! I was beginning to lose the will to live...

I believe you are correct. I don't think anyone has previously mentioned scoring the outline before. The initial router cuts I did yesterday to about 3mm from the final outline didn't actually generate much splintering, but scoring sounds like a useful idea, assuming it is done carefully with a sharp knife.

 

[Racers]

try googling the words "Joggle stick"

That's very clever, I'd not seen that before. Thank you. But I wish you'd mentioned it a month ago, I've just fitted and alcove cupboard with shelves, all of them anything but square. I did get it good, but it took me a lot of measuring and re-measuring of diagonals and cutouts. It took forever. I'll use one of these next time.

=D> =D>

Steve

I posted the same thing way back on page 3.

Pete

 

[Steve Maskery]

Ah yes, but you didn't use the enticing phrase "Joggle stick" did you?
But you can have a Thumbs Up as well, for lots of reasons.

 

[Jacob]

.....
At last, a useful post amongst all the irrelevant anti-CAD ranting! I was beginning to lose the will to live.......

Nobody is anti CAD ranting. CAD is excellent. It's just the wrong tool for your job. CAD is irrelevant to your project.

The right tool is pencil.......etc.....etc....Yawn.

 

[haggis999]

Nobody is anti CAD ranting. CAD is excellent. It's just the wrong tool for your job. CAD is irrelevant to your project.

The right tool is pencil.......etc.....etc....Yawn.

I've never met someone so spectacularly capable of missing the point. I never once suggested that CAD could solve my original question (I was always expecting the answer to be based on using a pencil and basic measuring skills). I have also repeatedly stated that CAD was irrelevant, so why do you keep banging on about it?

 

[Jacob]

If you own a good rule and straight edge you can dispense with the square.I know the idea gives lots of straight line and square corner woodworkers a dose of the vapours.By using the aligned dimension feature of a CAD system you can determine the distance from the ends of your baseline to any point on the periphery of the object.Where the arcs intersect locates your feature,join them with a pencil line and cut out the shelf from the completed outline.

I just drew the outline of the shelf in Freecad (guess how much it costs!) and took a screenshot ,which I hope will be displayed but its my first attempt at loading an image on this forum.

Well I think that actually could be useful! Using CAD as a calculator for the diagonals and then working up the drawing with A PENCIL!! (and a pair of compasses.)
For this sort of project you can fake a compass with a lath of wood - pin at one end, notches for pencil points as appropriate.

 

[Racers]

Nobody is anti CAD ranting. CAD is excellent. It's just the wrong tool for your job. CAD is irrelevant to your project.

The right tool is pencil.......etc.....etc....Yawn.

I've never met someone so spectacularly capable of missing the point. I never once suggested that CAD could solve my original question (I was always expecting the answer to be based on using a pencil and basic measuring skills). I have also repeatedly stated that CAD was irrelevant, so why do you keep banging on about it?

That foe button look inviting doesn't it.

Their are only two ways of doing something, Jacobs way and the wrong way.

Seriously Jacod drop it you are making us all look bad, the rest of us are a friendly happy to help tolerant lot, you are a pain.

Pete

 

[xy mosian]

Sorry to be late here.
I agree with those who suggest redrawing the plan on the wood in question. Use it as a drawing board.

However for more complex shapes the ability to print at full size, from AutoCAD would be useful.

In the Sketchup Plugin mentioned in my signature the solution I found was to redraw the original drawing in page sized chunks. These new drawings are sized according to the print sheet size with an overlap at each edge. This overlap has 'targets' added so that alignment can easily be achieved using pins, or fine nails through the centres. The drawing can then be transferred by using pins, nails or centre punches etc.. All this is done in the virtual world of course.
In my case the new drawings are presented in postscript format, which is accurate. Sadly to print this format most computers need a couple of, free, extra programs, but generally the process works well.
I am not sure how this could be achieved in AutoCAD but it may be an avenue worth pursuing.

I include acouple of images, of a seat template, which may help my explanation.

HTH, xy.

 

[nev]

Please no references to the above thanks. Just continue to help the OP and put the thread back on topic.

 

[haggis999]

Sorry to be late here.
I agree with those who suggest redrawing the plan on the wood in question. Use it as a drawing board.

However for more complex shapes the ability to print at full size, from AutoCAD would be useful.

As I mentioned on page 4 of this saga, I actually completed redrawing my plan on the wood surface yesterday morning, with the assistance of a full size AutoCAD print. However, I'm not too surprised you missed something that far back. Long threads can be difficult to plough through, especially when they veer a little off topic.

This afternoon, I also completed cutting out my first shelf. All went well and I am very pleased with the results. I took my time, as any serious mistake would have resulted in me having to buy another expensive 18mm plywood board. Galleywood's advice this morning to score the outline before firing up my router did an excellent job of preventing any splintering.

 

[Steve Maskery]

Very pleased to hear that.

 

[MrTeroo]

Yes. What a great result.

 

[xy mosian]

Well done that man!
xy

 

[Racers]

+1 haggis999, well done for riding the storm and making it safely back to port.


Pete