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Author Topic: 3 dimmensional trim path  (Read 5124 times)

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3 dimmensional trim path
« on: May 23, 2008, 08:06:34 AM »
I'm completely new, never touched a cnc machine. I'll be getting a starter cnc router, it would be from moosecreeksales on ebay. The job I'm looking to accomplish is trimming small fiberglass parts that have a 3d trim path, the bit can stay vertical. My question is, what would roughly be involved in programming a 3d path? I have a solid model of the part and can read the profile manualy. Unless there's an easier automated way to go from a solid model.

Offline zarzul

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Re: 3 dimmensional trim path
« Reply #1 on: May 23, 2008, 12:23:13 PM »
How to go from your solid model to a cut path depends a lot on what format the model is in. 

The 3d cam programs can be quite pricy.  You might want to take a look at freemill,  I believe it is by Vetric.

Arnie

Offline Sam

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Re: 3 dimmensional trim path
« Reply #2 on: May 23, 2008, 01:48:56 PM »
Quote
what would roughly be involved in programming a 3d path

Or, as I like to say it.... "I have a cat. It needs to be skinned......"  ;D
Seriously, if you've never touched a cnc machine before, going straight into 3d profiles is jumping into the deep end. Not trying to dissuade you by any means, but it can be a rather involved process. You will need a cam software package as zarzul stated. You will need time to learn the cam software. The learning curve on most software is very steep. The price is usually just as steep. If your fluent in 3DS Max, there is a free cam plugin called CNC Toolkit that might be worth a look. http://groups.yahoo.com/group/CNC_Toolkit It's been in development for long time, so it's sure to have drawbacks, but its free. The simple answer to your question is....

1. Time (lots of it)
2. Money (lots of it)

If you have both of these, this is an excellent place for answers to any questions that might (will) arise during the long journey.
« Last Edit: May 23, 2008, 01:51:00 PM by Sam »
"CONFIDENCE: it's the feeling you experience before you fully understand the situation."

Offline jimpinder

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Re: 3 dimmensional trim path
« Reply #3 on: May 24, 2008, 04:52:41 AM »
What size are the parts you are looking to trim, what is this trim path on the diagrams you have got. To trim the trimpath, will it require all three axis to move simultaneously, or can you fasten the part down on your table is such a way that only two axis need to move to follow the path (yes - the third will have to come down and up at the end - with the tool - but does not take part in the trimming)

To give you an idea - a CNC machine is programmed on a graph of X and Y with commands which move the cutter from where it is now, to where you want it. e.g. starting at point 0,0 - G0 X1Y0, G0 X1Y1, G0 X0Y1, G0 X0Y0 - will move the cutter in a square of 1 unit dimension. If you then want to add the Z axis up and down, you can add the z position to any line as well (in fact Mach3 will deal with 6 axis). As written, the axis move simultaneously - if you want one to move, it is the command followed by the axis to move.

If your drawings show positional information, then you can write programs from it. BUT to make it worth while, you really need to be repeating it a few more times - repeatability is one of the advantages of CNC - say a minimum of 6 depending on how quickly you can write the program. Also CNC does not do curves (apart from circles) so any curve has to be built up from little straight lines.

If these parts are all different - you may find that some form of probe tool and a mapping program would be an advantage so you could map the trim edge and run a program from that.

You will also have to take into account the diameter of your tooling - so you have plenty to go at.


Not me driving the engine - I'm better looking.
Re: 3 dimmensional trim path
« Reply #4 on: May 24, 2008, 04:05:19 PM »
the parts are approx 3x3in 1mm thick. there are 2 different designs and will probably run 100-200 of each to start, up to 10 at a time. all straight lines and radii. will need simultaneous 3 axis movement. models are in iges so all pretrimmed (except fringe) and trimmed dimmensions are known. will be making an hdpe jig with flat rectangular cuts to hold the pretrimmed parts. the likely bit would be 1/16 by 1/4 cutting surface.

how do I upload pics of the pretrimmed and trimmed parts?

thank you so much for the much needed help, I think I hit all the questions, i'll see if i missed any.
Re: 3 dimmensional trim path
« Reply #5 on: May 24, 2008, 04:10:48 PM »
let me clearify the dimmensions. The laminate is 1mm thick and the contours make the part about .75 in thick.
Re: 3 dimmensional trim path
« Reply #6 on: May 24, 2008, 04:36:23 PM »

Offline Graham Waterworth

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Re: 3 dimmensional trim path
« Reply #7 on: May 24, 2008, 05:12:22 PM »
That's not hard to do, 10 mins to program that one. that's a 2D shape with Z axis moves.

Graham.
America gave us powered flight, England the steam train and Germany the car.  Who invented the first boat?
Re: 3 dimmensional trim path
« Reply #8 on: May 24, 2008, 06:52:06 PM »
Could I accomplish this with open source/trial software? I got the mach3 but I'm still a bit confused from some of the comments about software requirements.
« Last Edit: May 24, 2008, 08:30:50 PM by snocutt »

Offline Graham Waterworth

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Re: 3 dimmensional trim path
« Reply #9 on: May 25, 2008, 04:55:13 AM »
I have sent you a personal message.

Graham.


America gave us powered flight, England the steam train and Germany the car.  Who invented the first boat?