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some More skis
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More



Joined: 04 Jul 2012
Posts: 112

PostPosted: Wed Sep 12, 2012 2:53 pm    Post subject: Reply with quote

Also, let's talk CAM.

Our skis are modelled in Solidworks, Less can talk a bit more at some point about our methods for CAD.

I'm CAMing at the moment using VCarve and Cut3d from Vectric (just what I've got). I had a play with MeshCam but it doesn't seem like it's quite there yet. Eventually we'll be using Mastercam.

So, from solidworks, we export the rabbet line and core sidecut, as a dxf. That all gets imported into Vcarve and located 10mm in on both x & y. Then I can do a pocket path for rebating the rabbet (heh) and a profile of the core sidecut as one gcode, grab the rabbet line and put a pocket inside it with a 0.1-0.2mm offset (still experimenting with the right fit here) for the spoil board pocket.

Then for the 3d stuff, in Solidworks we supress the sidecut and expand the camber extrusion by 10mm in X and Y. This negates Cut3d's awful and seemingly unavoidable habit of dropping the tool down off the end of things and requiring a pencil cleanup toolpath (which it doesn't really do). That body gets exported as an STL, and dumped into Cut3d with the 10mm inflated stock size, and then it'll drop straight onto the same spot on the table as the VCarve files, and won't touch the profiled sidecut of your precious, precious core.

Took a bit of thinking to get that straight in my head, so hopefully this helps someone in the same situation one day. Which will probably be me, once I forget. Confused
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falls



Joined: 27 Oct 2009
Posts: 1432
Location: Wangaratta, Australia

PostPosted: Wed Sep 12, 2012 4:26 pm    Post subject: Reply with quote

If the base material is really annoying you on the CNC to hold down then an MDF template with vacuum channels and cutting with a router by hand and a pattern bit really works well. The last pair I made I left the vacuum running to hold the base in place while attaching the edges and I found that my edge fit was the best I have yet achieved.
Agree with twizz about rolling the plastic in the opposite direction. I usually cut a 2m length and roll it in the opposite direction then sandwich it between 2 sheets of MDF (18mm) until I am ready to use it. If you have a lot of base material you can cut it to lengths and stack them and then their own weight helps to keep them flat (but that's prob more like production run volumes).
Cutting the bases on the CNC and then lifting them off to attach the edges does leave a bit of room for plastic warpage. Maybe cutting an MDF template that you can attach your base material to after cutting on the CNC for edge attachment would be worthwhile. Not sure what others who cut their bases on CNC are doing for attaching edges.
Mega jealous on your equipment also!
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Wed Sep 12, 2012 4:29 pm    Post subject: Reply with quote

You'll laugh at this Falls...

I don't have a router Embarassed


CNC or bust Very Happy

Yeah the equipment lying around at work rocks. It goes both ways though - doing this sort of stuff educates you about the machine and makes you better at your job. Or something.
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twizzstyle



Joined: 07 Mar 2006
Posts: 2198
Location: Kenmore, Wa USA

PostPosted: Wed Sep 12, 2012 5:10 pm    Post subject: Reply with quote

More wrote:
You'll laugh at this Falls...

I don't have a router Embarassed


CNC or bust Very Happy


Ha!!! I love it!

And yes, rabbit, rebate, all the same thing. I use the terms interchangably.

I don't have any pictures of my drag knife up here yet, but I will in a couple of days once I get some more pictures of these new pairs up. I am currently not doing any compensating for the drag, but my shapes have been very round with no sharp corners, so it's been ok.

On my CNC I just drilled a grid of holes a few inches apart and put 3/8" t-nuts on the underside, so that I can use normal machinist clamps. It works, but its not ideal, especially for small parts. When I get some time I may make some changes to do vacuum through MDF like you are, that's pretty awesome. I notice the table is a bunch of MDF laminated sideways, I assume that's because the porosity of the core is more so than the dense outer bit of the MDF.
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falls



Joined: 27 Oct 2009
Posts: 1432
Location: Wangaratta, Australia

PostPosted: Wed Sep 12, 2012 5:19 pm    Post subject: Reply with quote

Ha no router! Priceless.
Twizz here is a video about setting up a vacuum table (you know you want to). http://www.youtube.com/watch?v=sx8fAv5f8js&feature=youtube_gdata_player
I think they make "light" MDf which is more porous and pulls vacuum through it better once skimmed.
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Joined: 04 Jul 2012
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PostPosted: Wed Sep 12, 2012 6:24 pm    Post subject: Reply with quote

Nah it's not a light mdf, just the normal stuff. in a production environment you'd use coversheets, reject boards etc. once you skim both sides it gets plenty of suck - as long as the parts are reasonably flat (hence it falling apart for my bases).

It's actually not lamiated Twizz, what you're looking at there is the burring left by the skim cutter, which is a bit over an inch wide. because half of the fibres are orientated one way and half the other by a rotating tool, you get that stripped effect.
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twizzstyle



Joined: 07 Mar 2006
Posts: 2198
Location: Kenmore, Wa USA

PostPosted: Wed Sep 12, 2012 7:09 pm    Post subject: Reply with quote

Got it, awesome thanks! Absolutely on my list of projects/cnc updates now.
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Joined: 04 Jul 2012
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PostPosted: Wed Sep 12, 2012 7:13 pm    Post subject: Reply with quote

I'll take you a photo of what the vacuum bed looks like later tonight. might help your thinking.
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amidnightproject



Joined: 04 Nov 2009
Posts: 378
Location: Portland Area, Maine

PostPosted: Thu Sep 13, 2012 6:51 pm    Post subject: Reply with quote

More wrote:
Ha, ok, no worries.

So is there a consensus for a good practical cavity height? surely loading it must be a bit finicky if it's absolutely as tight as possible?


loading it is easy. Just hit the gym and work on your seated rows. Very Happy

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Joined: 04 Jul 2012
Posts: 112

PostPosted: Fri Sep 14, 2012 6:13 pm    Post subject: Reply with quote

That's pretty much the solution we've opted for, yeah. Thanks for the inspiration!

All go here, profiling cores right now but shitty CAM software means no offset climb cutting... and so here I sit, editing the code by hand Confused

Edge bender done, man, the Skilab edges are only JUST long enough for my skis. they're monsters.

We're going to do one pair with full core tips, one with an thin tipspacer just to see how that goes. Less is out buying layup consumables, fibre and resin are all here, PIDs tuning, Press is fully compliant... just about ready to push go!
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MadRussian



Joined: 30 Sep 2010
Posts: 682
Location: USA

PostPosted: Sat Sep 15, 2012 3:21 pm    Post subject: Reply with quote

More wrote:
I'll take you a photo of what the vacuum bed looks like later tonight. might help your thinking.



what size of vacuum pump you are using? I read at CNC zone for full-size vacuum table they are using 15 to 20 hp vacuum pump
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Joined: 04 Jul 2012
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PostPosted: Sun Sep 16, 2012 2:10 am    Post subject: Reply with quote

Depends a lot on the type of pump. The one on that CNC is just a blower - sucks a hell of a lot of juice (12kW) and doesn't draw that great a vacuum. On the flip side, they're more tolerant of the spoil board getting tracked out.

On our more expensive CNCs (Read: not for skibuilding) we have dry running claw pumps. kick ass for nesting, low power (more like 5kW) and draws a way, way better vacuum, but it moves less air, so it's less tolerant of the spoil board getting tracked out / being uncovered.


Some pics inbound shortly! then I've really gotta tidy up because it's 10pm on Sunday and the mess level at work is hovering between "awful" and "catastrophic".
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Sun Sep 16, 2012 3:04 pm    Post subject: Reply with quote

pic dump time...

Milling





Profiling




Bender - works best at 2 in the morning after a couple of beers, when I achieved a zen-like state of oneness with the bender, and perfectly cranked out a couple of edges in a row. The next day took AGES of fiddling to do the other edges. Moral - don't sleep and keep drinking beer.













Lasered the core - was looking to see if it would show through - seems to have done so alright on the bigger lines, but not good for text. would reserve this for blocky graphics in the future, but more likely is I'll just move to dye sub.




Frugal press loading equipment Smile worked REALLY well actually.


I've got a bit of practice to get smooth and fast with layup... need a better strategy in this area I feel.

I can't wait to cut these bad boys out. so far it looks like they've held camber and have flat bases.

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vinman



Joined: 09 Nov 2007
Posts: 1301
Location: The tin foil isle

PostPosted: Sun Sep 16, 2012 4:00 pm    Post subject: Reply with quote

sweet, nice progress.
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twizzstyle



Joined: 07 Mar 2006
Posts: 2198
Location: Kenmore, Wa USA

PostPosted: Sun Sep 16, 2012 5:25 pm    Post subject: Reply with quote

You have a laser too?!??? Ok I am WAY too jealous. I've always wanted to do laser-burned graphics on some bamboo veneer topsheets.

Nice job on the edges, that is still the hardest and most frustrating part of the whole process for me. Is that a constant radius tip? Try a tip with a changing radius, then you'll learn true frustration Wink I stopped dong full-wrap and do 3/4 wrap and it is WAY easier now.

Nice job, looks like they turned out great.
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