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some More skis
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Misha



Joined: 13 Jun 2008
Posts: 63
Location: Murmansk r/ Poljarnye Zori. Russia

PostPosted: Thu Aug 02, 2012 9:31 pm    Post subject: Reply with quote

wow!!!
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Murchonn
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Wed Aug 08, 2012 1:30 pm    Post subject: Reply with quote

Some heat mat drama ensued last night.

We've made 2 mats, one is on +45/-45 and the other 0/90.


We are trimming the mats down to 1cm past the outer heat wire. With a workshop light behind the mat, it was easy to see where our wires are:


A knife and a metal bar made short work of the trimming:




Then, tragedy, we put a multimeter on the plug and find out the resistance is wrong in one of the mats and a circuit was dropping in and out. Gutted.

After sitting around for an hour or so fiddling with the mat, we'd located the fault within a few square cms. Time for surgury. We set up a light box with a sheet of clear acrylic and the light under it, broke off a new section of blade on the knife, and really, really nervously started cutting into the mat, trying to get down 2 layers and not destroy the wire in case we had the wrong spot.



Success:


The resistance is correct when those tiny wires are bridged.

Tonight we'll open it up a bit further still, use an extra piece of wire to bridge the gap, then patch the hole.

So, a bit of a downer, but at least the mat isn't a throwaway.

The takeaway lesson for us is that 0/90 glass is not that great for this. When rolled, the mat tends to kink, and we reckon that's what has gone wrong here. The 45/-45 mat is much sturdier.
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Thu Aug 09, 2012 1:17 pm    Post subject: Reply with quote

Repairs done now on the dodgy mat. I think long term we'll be looking to replace it, but for now it's ok.

Some crappy phone pics-
Exposing a fault, bridging with copper shim. this was prior to soldering:


Patched up, plastic laid on and smoothed over for a good finish.


Next mat I make will be double bias or triax instead of biax, and thicker resistance wire. Learning, learning...
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Less (antonym)



Joined: 31 Jul 2012
Posts: 15

PostPosted: Thu Aug 09, 2012 4:58 pm    Post subject: Reply with quote

Kia Ora,

So I am the guy who looks super stoked to be playing with a massive crane. What can I say? It is pretty sweet. Thanks to all of you who have done this before. The learning curve has been steep. I can only hope the payoff/ride at the end can be steeper.

Regarding the mat builds, there were some advantages to using the 0/90 on the second attempt. The mat stayed much straighter during stitching and layup. The first one came out with a bit of a bow from having to work pretty hard pushing the silicone though. With the glass running full length on the second we could keep it pulled out tight and straight during layup. I think if we were wanting to go all out you would stitch the wire into a 0/90 layer and then cover top and bottom with +45/-45 to give it some resistance to folding.
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richie



Joined: 23 Jun 2010
Posts: 182
Location: New Zealand

PostPosted: Sat Aug 11, 2012 11:21 am    Post subject: wire Reply with quote

Argus heating in christchurch specialises in these blankets, and if you guys are still keen to build another one then use their wire, its kink resistant heating wire that is wound in a spiral around a core filler, so it will bend easily and not naturally kink where the blanket and 0/90 glass bends. i agree using triax might be safer too, i suggest spotting the wire down with small dobs of silicone to tack it down then do your big pour and wetout once the wire is held in position, otherwise nice job well done! think i might go play with my edge bender today, yesterday was working on my cnc z axis, all good.
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rich@splitn2.com | www.facebook.com/splitn2
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Sat Aug 11, 2012 2:49 pm    Post subject: Reply with quote

Cheers Richie, yeah definitely some things to do differently next time.

I've been working on the brain over the last couple of days. We're setting up a 4 output control box, 3 pids and a switched, for 2 mats, a heated postcure / warming box and air circulation for the box. The PIDs are cheapies from ebay (Sestos), pretty much everything else is salvage or scrap. Everything not through the panel is DIN mounted, everything earths nicely and all the circuits are fused with breakers.

I need to acquire another SSR before finishing the making the hotbox, or just run it on the alarm relay outputs of the PID I guess (not ideal).

Our sweet housing for the controls:


Making spaghetti:



I even did everything up nice with crimped terminals:


Nearing completion
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richie



Joined: 23 Jun 2010
Posts: 182
Location: New Zealand

PostPosted: Sat Aug 11, 2012 9:13 pm    Post subject: nice work bro! Reply with quote

Its cool to do this stuff eh, I find it very relaxing. I just spent the day in my shed building/testing/calibrating my MK2 edge bender which has come up sweet, and fitting new bearing guides to my bandsaw. So all good to improve the process and quality.

nice controller mate, yeah the crimps make it a whole lot safer and professional build quality and easier wiring up, plus easy to do mods on or rework without all the normal wire strands getting all hairy!

cnc Z axis got some love yesterday cleaning up the linear guides and ball screws, sorting out all my parts I have accumulated so I can work out whats needed to finish it.

Can you flick me Krish's email I can't remember his website it was some long name eh.

Can't wait to see how your ski's turn out, your preparation is excellent I have little doubt you will turn out great end product.

cheers
Rich
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Sun Aug 12, 2012 12:08 pm    Post subject: Reply with quote

Made up some tip and tail mould blocks yesterday on a cnc.

We used a vacuum bed machine, so first up we skim the spoil board to remove the tracks from previous jobs and get good hold down:


Then I have to nervously watch to see if we've screwed something up with the CAM...


Parts are nested:


The parts are tabbed as well as vacuum held, so I have some cleanup to do on the blocks (knife and a lick with some sandpaper):


Meanwhile, I made some thermocouples. We just bought a reel of thermocouple extention wire - much cheaper than buying the actual thermcouples and you can get the ends really small.. Weld the ends together and hey presto, cheap thermocouples of whatever length you want.


Jimmy insists that thermocouples are too much like magic, and he has a point.
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skidesmond



Joined: 07 Apr 2009
Posts: 2283
Location: Western Mass, USA

PostPosted: Sun Aug 12, 2012 4:02 pm    Post subject: Reply with quote

Nice to have big boy toys (CNC)! Looking great!
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Sun Aug 12, 2012 5:15 pm    Post subject: Reply with quote

Sure is! I'm wondering if it is possible to use an edgebander to apply sidewalls - got plenty of them lying around too... Idea
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Mon Aug 13, 2012 3:42 pm    Post subject: Reply with quote

Had a request for more info on the thermocouple wire, though I'd put it here where everyone can see it.

Thermocouples work by using a weird little effect where the joint between two different conductors (i.e. different types of metalwire) produce an small electric potential (i.e. teeny weeny voltage) related to the temperature of the junction. This is neat because it powers itself - you don't need to pass a current through it like with a resisitance based measure.

So because it's just a dissimilar metal junction, you can knock one up yourself. Thermocouple extension wire is readily available, because if you're worried about accuracy, you shouldn't extend a thermocouple with anything else (more junctions, right?).

This is what's left of the the reel of T-type that I got:


[url=http://newzealand.rs-online.com/web/p/thermocouple-extension-wire/3630402/ ]This is where I got it from. [/url]
RS is normally pretty expensive relative to other sources, but they have a decent online order system and can get things to me the next day (not to be sneezed at in NZ).

From that reel we've made something like 10 thermcouples, and three of them are 4m long for the press (the rest for coffe roasting stuff), so it's a cheap way to go if you have a bit to do or anticipate doing more in the future.

After you've got the stuff, you just strip the ends, twist it together, and try and dial a gas torch as low as possible to weld it. I've heard of people using capacitor banks but that sounds hard. It's literally a <1 second touch with the torch.







Hope that helps someone!

We glued up the tip and tail blocks last night.





They were doweled with 12mm steel rod (drilled on the cnc). locating was pretty simple then, but they still got a few clamps and a lick of sandpaper to get everything perfectly flush.

cheers.
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twizzstyle



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

PostPosted: Tue Aug 14, 2012 7:33 am    Post subject: Reply with quote

That CNC puts mine to shame. Keep up the good work!
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Joined: 04 Jul 2012
Posts: 112

PostPosted: Tue Aug 14, 2012 1:11 pm    Post subject: Reply with quote

No Twizz, you actually made yours, it's embodied work makes it way cooler!

Zipped up a camber board last night. The final pass was done with a ball nose cutter at a 0.5mm stepover. Probably overkill. Definitely felt like overkill, it took ages!

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Joined: 04 Jul 2012
Posts: 112

PostPosted: Wed Aug 29, 2012 12:23 pm    Post subject: Reply with quote

After WAY too long pissing around with heater mats, I got my moulds mounted last night.

I have a bit of extra height in the cavity, so I used the spacer boards to make the moulds easily demountable and movable. I cut up some threaded rod into short sections and gas welded it into tee bolts, then embedded the t section inbetween 2 spacer boards. The result is threaded rod sticking up out of the moulds that line up with the gaps we left between Ibeams in the press - a big washer and a nut on the other side and they can slide backwards and forwards on (or hanging from) the press bed before tightening them.

I'll make up a ribbed spacer section for the top this weekend, and mount it the same way. Then I'll pretty much never have to demount the cat track.

I really should have taken pictures instead of trying to explain that in words...
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falls



Joined: 27 Oct 2009
Posts: 1427
Location: Wangaratta, Australia

PostPosted: Wed Aug 29, 2012 7:05 pm    Post subject: Reply with quote

I'll second that!
But I think I'm with you.
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