Styro-Schneidedraht: Lieferant?

Hello everyone,

I would like to ask anyone of you that could help me find a particular product from Germany.

Some years ago (at 2013) I bought from r-g composites some meters of polystyrene cutting wire 0.4/0.5mm.

I am very pleased with this product and have not found anything better than this, so I would like to buy more of it but r-g do not provide this product anymore and I do not know what brand it was or from where to buy it again.

So please if anyone who has bought this cutting wire or knows something about its brand let me know.

I would be very grateful if someone help me find this product again!

My best regards,
Tasos.
 
Thank you for your kind response,

Searching back in my 2013 order documents from R&G have found the following description of these wires:
- Item Nr 4051000
Polystyrene cutting wire 0.4mm/10m pack
-Item Nr 4051001
Polystyrene cutting wire 0.5mm/10m pack

For just the 0.5mm r&g had basic properties description…
Tensile strength :> 210N and resistivity 5 Ohm/m/ 3.5A current

rc-letmathe.de lists the same properties for their 0.5mm wire so I guess it probably is the same product…but has anyone actually tried these 0.4/0.5mm wires?

I cut foam for more than 25 years and the wire i bought from R&G was very high tensile strength almost comparable to Rene 41… even the best 80/20 Nichrome is very inferior as elongation during tensioning is quite high not to mention other problems.

I sincerely appreciate your kind help!
Tasos.
 
Piano wire

Piano wire

Hello,
use piano wire (I mean, wire for the music instrument!) or better Cembalo wire which is available from piano workshops with a diameter of 0,6mm. The wire ist very strong and lasts forever,
Stefan
 
rc-letmathe.de lists the same properties for their 0.5mm wire so I guess it probably is the same product…but has anyone actually tried these 0.4/0.5mm wires?

0.4mm cutting wire from Letmathe is perfect. I am cutting panels up to 750mm length in extruded PS foam, mainly densities around 28-30 kg/m³.
Even very thin and short airfoil sections (~5% DLG) work fine; much better as with 0.5mm wire. You do need some preload and elongation compensation.
Very important to set right values for inner/outer kerf. Sometimes just try_n_error ;-)

Assuming you do CNC cutting. By hand this is a totally different story.

Regards
Mike
 
Hi Mike,

Thanks for the info,

Can now assume the 0.4/0.5mm wire from Letmathe is same product R&G listed years ago… have used these wires for a number of years and had very good mechanical properties, hence my search for the same product.

Is there any way for us to know of chemical composition? It is obvious they are not just plain 80/20 Nichrome.

Of course elongation compensation is accounted for in my bows plus many innovative features…kerf allowance is a more difficult story depending on actual heat transfer of each specific wire size and cutting temperature…speed is also relevant so for results of even moderate accuracy (+/-0.1mm) one a lot of work to do.
Actual results are almost never as predicted as there are a lot of variables to play a role…but as we all found out step/minute adjustments and much patience can lead to first rate results.

I am an old school cutter and for now I continue to do manual work…have contemplated to make a move for CNC but always postpone it for a later time as I get excellent results manually…had contacted cnc-multitool in the past… they are very friendly and helpful but stated that best accuracy results can be at more or less 0.1mm.

My adjustable templates can yield results of slightly better than that and quite fast set up/rigging that so I am still just searching for a really high accuracy small CNC cutter…not to mention CAM foam software which is probably the biggest story behind cnc cutting…to my uninitiated mind proper choice can mean success or mediocre/ disappointing results.

Maybe I am just too fanatical about precision but this is the only way to get predicted results of new generation program designed airfoils.

Regards Tasos.
 
Hi Tasos,

I had a link to a supplier for special wire, don't find it anymore. For sale in the range of about 5kg spools, not very attractive.
Some time ago he told me that he has a special alloy for professional hotwire application. Also he recommended to buy small quantities of his material at R&G.
Ok, that is over.

So, why don't you try that stuff from Letmathe? Even with freight it is dirt cheap.

Building a CNC hotwire cutter is no big deal. Making templates for hand cutting is some how boring and too much time-consuming when you are on different projects.
Unless you mill the templates with a CNC ;-)

I am working with the old Profili, it has all I need. But there is newer software, maybe worth a try:
http://www.foamcuttingsoftware.com/eng/devwingfoam.asp

Once you have a CNC foamcutter you never miss the oldfashioned way.

I do not quite understand what you need the accuracy for. When you sheet with obeche or balsa the surface is not very accurate.
When you are working with fibres and Mylar aka Phil Barnes your limiting factor is the Mylars.

Next way to ultimative accurate production would be milling foam cores.
And pressing in CNC made negative moulds :-)

Regards
Mike
 
Hi Mike,

Just got back from my workshop after my usual 14h shift…I do custom upgrade carbon joiners for competition mainly for F5J/F3J ships and CNC produce my own line of super thin (0.1mm) 3D turbulators… among many other projects.

Your notes are just on track and will agree with you on most except accuracy, (I do not refer to wood planked wings of course)...what I have found out during many years of F5J competing and designing/building/producing is that accuracy on reproducing high performance sections can really make a difference in actual flight.

It is late night here in Greece so will just say this…the turbulators I produce are just 0.1mm thick and the actual flight difference on those highly accurate F5J wings must be experienced to be believed!!!

More thoughts on cutting wires and CNC stuff tomorrow…for now I sincerely want to thank you for taking time to provide info and respond to my silly mumblings! :)

P.S. My templates are all laser cut of 1.5mm aluminum.

Regards Tasos
 
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