[chbot] Banggood?

[Stephen Irons]

Spectra and Dyneema are brand names for high molecular weight 
polyethylene (HMWPE or HMPE). It is used for fishing lines, kite lines, 
standing rigging and control lines in sailing, and as wire-rope 
replacement in winching and lifting applications (and other 
applications such as body armour).

It is light (less dense than water) and very strong. It has excellent 
resistance to abrasion, UV and many chemicals. It hardly stretches at 
all, but does creep under high load. It is very slippery.

Some of these characteristic might make it less suitable for your 
application:

It is very slippery, much more so than nylon fishing lines, so it 
difficult to join. It is possible to splice the ends together to make 
an endless loop -- a small loop is sometimes used on boats as a 'soft 
shackle'. There are instructions around for splicing.

Control lines for yachts are usually covered in a sheath made from a 
different material, so that it is possible to grip the rope. Other 
boatings applications (eg. stays, soft shackles, winch cables) are 
usually bare.

You can buy the stuff in various different sizes from different sports 
shops: fishing shops, kite shops, boat shops, etc. Fishing braid is 
usually thinner, while boat control lines range from 2 mm up to 14 mm.

Boat shops (Boat.net.nz, Oborns, Burnsco) have sizes from 2 mm diameter 
up to 12 or 14 mm.

Stephen Irons


On Mon, Sep 25, 2017 at 1:55 PM, Andrew Errington 
<erringtona at gmail.com> wrote:
> Thanks Jeremy.  A quick Google gets me some local suppliers and 
> places to look.
> 
> My problem may then come down to tensioning the cord.  We'll see.
> 
> Thanks,
> 
> Andrew
> 
> On Sep 25, 2017 1:31 PM, "Jeremy Reeve" <jsr73 at uclive.ac.nz> wrote:
>> 
>> Hi Andrew,
>> 
>> 
>> I know some people who used something called Spectra Line as a drive 
>> for their Cerberus delta type printer (1m tall).  
>> http://www.spectrafishing.com/  It's a fibre rather than 
>> monofilament.  There are some special grooved bobbins available to 
>> fit stepper motors but I don't know where they came from.  Maybe 
>> getting the required tension is still a problem for your application 
>> though.
>> 
>> 
>> Jeremy
>> 
>> 
>> From: Chchrobotics <chchrobotics-bounces at lists.ourshack.com> on 
>> behalf of Andrew Errington <erringtona at gmail.com>
>> Sent: Monday, 25 September 2017 10:00 a.m.
>> To: Christchurch Robotics
>> Subject: Re: [chbot] Banggood?
>> 
>> Thanks everyone.  I'll start using them.
>> 
>> As I said, I have never had a problem with DX, it's just that they 
>> aren't stocking the esoteric items I'm looking for.
>> 
>> At the moment I am looking for GT2 belt (as used in 3D printers) in 
>> white, because I am going to use it for automatic curtains, and 
>> black would look bad.
>> 
>> DX has 10m in black (only) for $8, BG has it in white for $12.  DX 
>> has no stock of the GT2 pulleys, BG has all the popular variants.
>> 
>> I have also noticed a few guys on TradeMe are reselling a lot of the 
>> cool modules, parts, and tools that you see on the Chinese sites.  I 
>> ordered some black GT2 belt and some pulleys for more testing.  I'll 
>> get them in a couple of days, but they're more expensive of course.
>> 
>> I tried using builder's line.  It doesn't stretch but I can't get 
>> the tension I want.  I tried fishing line, but it does stretch, and 
>> I found it snarling up on the drive pulley.
>> 
>> Thanks,
>> 
>> Andrew
>> 
>> 
>> 
>> 
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