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calibanman
21-08-2014, 01:42 PM
Help.......Could someone please help me with a problem that I have.

I work for a firm that fits panels made out of plywood to the inside of vans (ply lining).

We have just acquired a CNC machine and I have been given the job of getting the templates that we have made of plywood panels into VCarve Pro 7.5. I have tried taking photographs of the panels and using the trace option and also drawing free hand. Is measuring the panels my only option left? The trouble with that option is that most of the panels are made up of irregular, complex shapes and are not easy to measure, if at all giving my lack of geometry skills.


Thanks for any help received , however small, as I am a complete novice at this.

The machine is a Spartan 1325 from Radecal. :grumpy:

Blackrat
21-08-2014, 07:59 PM
I have tried taking photographs of the panels and using the trace option and also drawing free hand.

why doesnt this method work ?

EddyCurrent
21-08-2014, 08:05 PM
You need some CAD software ideally, such as Sketchup or there are others. As it's just flat sheets it should be very easy to draw up. I think VCarve Pro does include CAD facilities so you may be able to draw your panels just using that software.
Sorry to sound harsh, but it's similar to what someone said here recently, if you struggle to measure up and draw some flat panels you might need to think twice about using a CNC machine.

There's a list of software here that may have something you could use for CAD; http://www.mycncuk.com/threads/6707-List-of-CAD-CAM-Software

Here's a video of someone drawing gears using VCarve Pro;


https://www.youtube.com/watch?v=8CUounvB-xg

gorbo
21-08-2014, 10:15 PM
I would go for the trace way but you need datum points to keep scale of the piece, trace function works best with clear defined edges to work to try using black and white photos

EddyCurrent
21-08-2014, 11:01 PM
I would go for the trace way but you need datum points to keep scale of the piece, trace function works best with clear defined edges to work to try using black and white photos

That's the last thing I would do but maybe that's just me ?

GEOFFREY
21-08-2014, 11:10 PM
Me too Eddy. Just draw out an accurate grid on the pattern, measure and transfer the dims from the grid to a matching grid on the cad screen. Good luck. G.

EddyCurrent
21-08-2014, 11:56 PM
You could use your machine to probe an existing template or do it manually. Put a pointed tool in the collet, jogg the X axis a set amount each time, bring the Y axis across until the point is on the edge of the template, make a note of the X,Y coordinates, then it's easy to recreate it in your CAD software. Joint the points using curves, straight lines, or whatever is appropriate.

Here's a video of a cheap to make probe that could do the job, a better one would just trawl around the outside edge itself.


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

JAZZCNC
22-08-2014, 12:39 AM
I don't use Vcarve pro but this is easy to do in any Cad/Cam package and I do it all the time for parts that don't need high accurecy. It's just a matter of scale and if you have templates to reference from then it's no problem.

Easy way is to draw 2 lines the length and width of the part then scale the photo to these lines. This will get you to within nats bollock in size then just use the trace function or as is often the case it's just as quick to free hand trace around the picture. Then create G-code and cut air around your original template to see how it matches. Make any changes as needed.!!. . . . . Simplizzzz.!

phill05
22-08-2014, 01:09 AM
This is something I have done with irregular shapes, I cut a piece of white paper as large as possible and mark the size on it (this helps when you are doing different shapes), line it to one edge of ply that is straight and tape or glue it in place.
Take a photo of the ply (must be square to the camera) preferably with a contrasting background.

Import bitmap for tracing in VC pro7, trace bitmap, select Black/White, move Bitmap fading to 0 press Preview, press Apply.
Select & delete image, create a box/ rectangle to given size of White paper and position 1 corner to a corner of the white paper vector, select all then deselect box/rectangle re-size outline vectors to fit to box/rectangle.

This is a quick & easy way to do it but you might have spend some time to clean up the vector lines a little.

Another way If you have a large amount to convert is buy a Image to Vector program that will provide you with much cleaner vectors to work with and produce better cutouts on the cnc.

Phill

Ger21
22-08-2014, 01:23 AM
I've been doing this on a semi regular basis for almost 20 years now. My preference for large items is to measure and draw in CAD. For small stuff, I'll scan, and import into CAD, and hand trace.
This gives the most efficient code, and there's no cleanup required. It does require decent CAD skills, though.

gorbo
22-08-2014, 01:33 AM
That's the last thing I would do but maybe that's just me ?

I have used this method with success, but that's just me

EddyCurrent
22-08-2014, 08:32 AM
I'm pleased it works for you and I too have used it for small items but how far away from the existing panel template would you need to be to get a photograph without lens distortion ?

JAZZCNC
22-08-2014, 11:13 AM
I'm pleased it works for you and I too have used it for small items but how far away from the existing panel template would you need to be to get a photograph without lens distortion ?

Eddy these panels have HUGE margin for error in CNC terms so it's not a problem.! . . . How do I know.? Because I did exactly what I suggested when I upgraded our Ducato Van at work. It was same Shape Van as previous model so ripped out old knackerd panels for templates and took Pic. Worked like a charm dropped a pencil in spindle drew shape on board for comparison and was within mm's.

EddyCurrent
22-08-2014, 11:14 AM
Another way If you have a large amount to convert is buy a Image to Vector program that will provide you with much cleaner vectors to work with and produce better cutouts on the cnc. Phill

This is a good free program it also exports to dxf; http://www.wintopo.com/

Boyan Silyavski
22-08-2014, 03:37 PM
Hi,
i happen to be a pro :tears_of_joy: photographer, apart from all.

FYI the real proper way to this is the following:
You need camera, tripod, contrasting wall/best buy from ebay proper green background/ or paint a wall dark electric green, Photoshop, Vcarve.

1. Do a Google search and find what is lens calibration. Download from adobe site the lens calibration utility. Go to a print shop and print one of the sample square grids.
Hang it on the wall. Make all the necessary photos in camera raw using tripod, camera squared to the center of the grid hanging. Follow their instructions precisely and at the end you will have a lens profile for that particular lens on that particular camera sensor.

The end result would be that when you make photo in RAW format with that setup, Camera raw will apply the profile automatically and you will have perfectly dimension rectified photo.

2. then use v carve trace.

that simple.

PS. Resources / i did the search for you as lens calibration could mean other things too/. Dont use ready lens profiles, as if you aim precision of distortion correction it could be lens and camera specific, not always, but better be sure.
http://www.computer-darkroom.com/blog/lens-correction-profiles/
http://helpx.adobe.com/photoshop/digital-negative.html#resources
http://www.peachpit.com/articles/article.aspx?p=1620779&seqNum=7

PS2. Lens calibration could be done even on mobile phone lens, but then you will definetely need some knowledge of camera Raw and Photoshop.

PS3. List of supported lens/ that have already profiles/
http://helpx.adobe.com/x-productkb/multi/lens-profile-support-lightroom-4.html

PS4. the photo could be taken as JPG, though RAW is better. You can open the JPG as Raw format, in Lightroom and Camera Raw browser. Ctrl+R comand

EddyCurrent
22-08-2014, 04:30 PM
silyavski, good one.

It looks like RawTherapee works with the profiles, and it's free !
http://rawtherapee.com/forum/viewtopic.php?f=15&t=5565
http://rawtherapee.com/downloads

With regard to the panels, I'd still be measuring and drawing I think, even if it's just for the practice.

cropwell
22-08-2014, 04:44 PM
I often wondered what use RAW format files were. My camera files images as JPG and RAW and I have never had a real use for it so far. Thanks Silyavski !

Lee Roberts
22-08-2014, 05:26 PM
Raw is what the pro's work from in photography, its basically a lossless format, any other format typically means the photo loses details and so on.

.Me

njhussey
23-08-2014, 09:18 AM
You can import a jpg file into most cad programs as a reference image and then on a different layer trace round the outline of the panel with lines, arcs etc. If you measure one straight edge of the template you can then scale your drawing after you've drawn it. I use this for converting old RC plane plans to CAD drawings...scan them in, trace round the lines, scale and then you're done...simples[emoji6]

EddyCurrent
26-08-2014, 05:46 PM
@calibanman, how did it finally work out for you ?

calibanman
26-08-2014, 07:11 PM
why doesnt this method work ?

Hi Blackrat

When I take a photograph, we're attaching the template to a wall at its centre of the panel, then keeping it square with the spirit level. The camera is set up on a tripod and the centre of the lens is the same height as the centre of the template. I then move the tripod with camera backwards or forwards on the centre line to get the image full frame, not using the zoom. I then adjust it to get a good contrast between the wall and the template in Photoshop.

I then import it into VCarve. I've used the trace function, but being plywood the outline didn't come out all that well (jagged). I now zoom in and draw round the shape with a Wacom tablet and pen. Having measured the maximum x and y values, I then scale my vector shape up to them measurements and create the toolpath. When cut, the shape is always about 1mm to 2mm out and not dead on.

I need them to be spot on because otherwise I will have to re-cut a corner or shave an edge which then takes time and we did buy the machine so we didn't have to cut them by hand, saving time. We then intend to nest them cutting down on waste as well.

EddyCurrent
26-08-2014, 10:43 PM
I need them to be spot on because otherwise I will have to re-cut a corner or shave an edge which then takes time and we did buy the machine so we didn't have to cut them by hand, saving time. We then intend to nest them cutting down on waste as well

Can't you import them into Inkscape for example and edit the vectors ?

JAZZCNC
26-08-2014, 11:47 PM
When cut, the shape is always about 1mm to 2mm out and not dead on.

You won't get them any better than that using this method without getting deeper into it like Silviski mentioned .!. . . .or drawing them from scratch.
BUT I don't see the problem here.? Get your basic shape imported then tweak the error out in CAD. It's a one time deal after that intial first import and tweak you have perfect templates.
You don't need to waste material for the intial test just put felt tip pencil in the spindle and draw out the shape and compare against your original template. You see the error and it takes 5mins to correct and away you go perfect parts every time.!!

martin54
27-08-2014, 01:19 AM
As I said on the vectric site, easy enough with a good photo, I've recently done a front window for an airport bus from 6mm acrylic because they couldn't get hold of a glass panel for several weeks.
Both front windows were same so used the one that wasn't broken, masking taped round the edge to give me good contrast, took photo, imported photo into software, drew round the edge to give my shape (don't generally use an auto trace) & plotted the shape to a large bit of paper. Cut out the shape & compared to original window, was a bit out in one or to places so noted where & made alterations to nodes. Plotted & cut out again but was still a little out on one edge so repeated the procedure & third template was spot on.
Your panels aren't fitted to the vehicle so you could draw on new stock with pen as Jazz has said.

phill05
27-08-2014, 05:00 AM
Hi Blackrat

I then import it into VCarve. I've used the trace function, but being plywood the outline didn't come out all that well (jagged). I now zoom in and draw round the shape with a Wacom tablet and pen. Having measured the maximum x and y values, I then scale my vector shape up to them measurements and create the toolpath. When cut, the shape is always about 1mm to 2mm out and not dead on.

I need them to be spot on because otherwise I will have to re-cut a corner or shave an edge which then takes time and we did buy the machine so we didn't have to cut them by hand, saving time. We then intend to nest them cutting down on waste as well.

You have done the hardest part now all you need to do is tweak the Node edits until you have a perfect fit.

Boyan Silyavski
28-08-2014, 09:47 AM
What about fitting a probe on the machine and measuring only the critical points? Wouldn't be easier for you?

calibanman
01-09-2014, 09:25 PM
Hi EddyCurrent (http://www.mycncuk.com/members/10308-EddyCurrent)

I'd like to thank everybody for their contribution to my problem. I've drawn round the shapes in VCarve, turned the CNC machine into a plotter and made my adjustments with the node editing, then cut them out. Up to now everything seems OK.

So thanks again. But I warn you, I will most probably be back with a new set of problems in the near future.

EddyCurrent
01-09-2014, 09:34 PM
Thanks for any help received , however small, as I am a complete novice at this

Sounds like you've become an expert in a very short space of time, spot on.

Boyan Silyavski
11-09-2014, 02:33 AM
FYI and for the sake of knowledge :-) , good for small business and fast turnover.
http://www.logictracetocut.com/LogicTraceEssential.htm
http://carlsondesign.com/digitizers/t-bar-digitizer
http://www.fastcam.com/fastcopy.html