Reply with QuoteI think it's a personal preference. I use a combination of both, depending on what I'm working on.
Dan
Normal profiling or 3 axis curve milling?
Hi,
I'm practising cutting wing mould shapes - negative shape so it's like a dish cut into the surface, with a leading edge that curves up tightly.
Anyway, I've been using the normal 3D surface milling but noticed the "3 axis curve milling" function.
Is there any benefit in using 3 axis curve milling to cut the shape, compared to surface milling??
Andrew
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I think it's a personal preference. I use a combination of both, depending on what I'm working on.
Dan
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Dan, when I tried selecting the concave wing shape's outline as the region curve, initially for the finishing planar cut it wanted to cut the shape but also to cut the profile around the shape (ie the cutter dropped down into the flat area I want as the flange). So I changed the settings to "stop at parting plane" and it confined the cut to the intended area and didn't touch the flange, however each time the cutter ran from trailing edge to leading edge, (it was doing 45 degree parallels from TE to LE) the machine kept nibbling the spindle around in the leading edge area, wasting time and making some unwanted marks in the LE, before starting the next cut line. Even though I had a small radius lead-in set, it didn't go above the shape to change direction. Should I change this by 1) unchecking the stop at parting planes, and 2) using the wing shape as boundary curves instead of region? Or does anyone have any advice on the best settings to use? This is kinda important to me because cutting these negative wing shapes is the most important thing for me to learn to do just now.
I think I would need to see your model, with toolpaths to make any kind of educated guess and/or suggestion on how to proceed.
Dan
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)
Why don't make a model downloadable somewhere and describe what you want to do (specify preferred moulding technique, mould material etc) and I'll have a go with it. Or Dan. Or both. Likely.
Guys, firstly again I have to say thanks very much for your help. It's an amazing world to be able to sit at a computer asking questions and have experts from all over the world chipping in voluntarily to help. Much appreciated.
I have uploaded the file that I've recently been working on. You can download it HERE
I'd really appreciate any advice on how to best handle it. My strategy so far after much trial and error has been to:
1) create a top plane and select that for the facing
2) hide the plane and reselect the mould shape. Using a region curve around the 3D wing area, do a roughing, then a Z level at 60 degrees limit, then do a planar finish at 50 degrees limit.
3) I go to the layer for the trailing edge trench (created earlier and hidden in a separate layer) then select it as the model, select its top curve as the region, and do a Z level cut into it.
4) Then do each hole as a pocket with an undersized cutter (it has to be a particular diameter).
5) Then profile cut the outside of the mould.
I have numerous questions ... to be honest I wish I could hire someone to sit with me for a few hours and work through what I'm doing.
A couple of the obvious questions:
When creating a number of toolpaths (say facing, roughing, z level then planar) do subsequent toolpaths make their calculations based on the amount of material left from previous cuts? Or is each toolpath calculated independent of previous cuts? I am sure that they do look back at previous cuts because the Z level affects the planar finish. But that brings the question - if you recalculate an earlier path (eg if you change the cutter or stepdown for the roughing cut) do you then need to go through each of the subsequent planar toolpaths and tell them to recalculate?? Does it make any difference to this if the path layers are hidden, or locked? Is it essential that they are in the right order in the list for recalculation? Or ... if you want to edit an early cut in this way, is it better to go right back to square one and create each path new, rather than recalculating them? (whew, I'm gonna overload you guys!).
If I create a toolpath but then decide to change the cutter and then recalculate the path, it doesn't change the name of the layer and still has the old name, so I have trouble working out what cutter it is now set to (unless I postprocess it and look at the report). Is there an easy way to tell what cutter is currently selected for a path?
Similarly with regions - (I'm probably not smart enough to ask the question coherently ...) if you close the file and re-open it, you have to re-select the model before you can edit any toolpaths. Does it remember the region curve selections or do you have to re-select those every time you re-open the file?
The biggest issue I have with getting an optimal 3D finish toolpath for the attached model is this: I want to avoid the cutter from doing changes of direction right on the leading edge curve as it can make it a bit messy. Ideally, I'd like the cutter to run in parallel X cuts from trailing edge and up over the leading edge (LE), out into the air above and outside the LE, then re-enter cleanly for the next pass. I set the shape of the wing as a region curve and did the a planar finishing with parallel X, but the cutter did lots of little movements around the LE on each pass, wasting time and making some unwanted marks. I got around this by doing a Z level finishing cut at 60 degrees, then doing the planar finishing at 50 degrees. This resulted in it completely avoiding the LE area, but the path still jumps up to the outside of the region then back in again ... and at the end of the run it goes along trimming up and nibbling around the very corner of the leading edge, which I don't want. I found that I could prevent this by selecting both "stop at parting line" and "exclude flat surfaces" but then it didn't cut a small spot in the middle of the wing, where it was flat! I would really like to know how to get around this!
If I select the 4 circles and "drill" them using a smaller ball cutter and pocketing, it does one Z level traversing from hole to hole before moving down a Z level then running around all 4 holes again. Is there a way to select all 4 holes and have the machine do all the work on one hole before moving to the next? My workaround is to do each hole's toolpath separately.
Very sorry for the overwhelming amount of questions ...
Cheers
Andrew
Dammit! You ask more question than my three year old son!Originally Posted by AvB
Tool paths don't care about each other, the only after coming paths you might have a need to recalculate are remachining (reroughing etc).
You need to reselect the model after a restart as a security function. Restrictions (region curves) affect the working box so yes they need to be reselected.
I haven't checked the model yet. Do you have a Skype account? If you have, send me a PM and lets do the modelling together. I stopped reading. Too much text.
Last edited by svenakela; 01-16-2014 at 12:46 PM.
Well, Andrew. I think we can agree that most stuff is sorted out now.
With this learning curve profile you will very soon be really good at this...
The details of my progress have been blogged on a thread on RC Groups, which is a forum for radio control, and at the moment I'm trying to learn to make nice moulds for composite RC gliders.
http://www.rcgroups.com/forums/showt...968257&page=10
I have to say a huge thanks to Sven. He offered to help me work through my problems via Skype. I am truly humbled, as he spent more than 2 1/2 hours solid with me working through things from the ground up. I learnt a lot, and kept working at it trying different options until we ended up with a new set of toolpaths that look good, and which, after sorting out some Mach3 tuning issues for CV, I've now been able to use for a great cut.
We spent the bulk of the time talking on Skype via my Macbook Pro sitting beside me, while screensharing the Windows PC via a site called joinme.com. This technology just blows me away. Two separate computers in my shed on a hot morning in Brisbane Australia, both streaming to a guy who's at 1am in Sweden with snow falling outside. The sound quality etc was perfect. We could be looking at the drawings on the screen in Rhino, then I'd pick up a mould and show him something on Skype, then back to the drawing.
Sven's a really cool guy. I don't know how he does all the stuff he does. He's a prototype engineer and works his own business as a contractor/ consultant for the big companies. He has his own workshop and makes cool stuff with big mills. He's a hard core sailboarder and has his own brand of sailboards and surfboards and wave sails in Sweden in the middle of winter. He has a sideline business repairing carbon fibre bike frames for various Euro teams, accredited for insurance work etc. He has 2 young kids and yet is happy to spend hours helping someone like me. I'm definitely humbled and won't complain so much any more about how busy I am!
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