DIY GRCS

[mtt.tr]

6 minutes ago, Paddy1000111 said:

Possibly? It's all the same stuff though, just 2 different methods AFAIK. I've not seen things go black from hot dip? My Flying capstan is hot dipped and rope blackening isn't an issue I have had. I know that you get 5x more protection from hot dipping though, even if electro-plating is shinier. Could always make it out of stainless like a 304L or a 316L and just make it shiny  

 

 

Guess my view is based on old weathered zinc that leaves staining. 

 

Ultimately an ali alloy is probably best option 

 

 

[Paddy1000111]

From my time in aviation a 7075 T6 would be ideal. A little lower shear strength than mild steel (331 vs 400mpa) but a much higher tensile yield (503 vs 370mpa). Easier to machine too if you draw up a design you could have someone mill something sexy. I was tempted to machine up a plate on my mill and then get it anodized but I felt like a steel plate would last longer. Not sure why though, Harkens rigging plate is ally! 

Edited December 8, 2020 by Paddy1000111

[mtt.tr]

22 minutes ago, Paddy1000111 said:

From my time in aviation a 7075 T6 would be ideal. A little lower shear strength than mild steel (331 vs 400mpa) but a much higher tensile yield (503 vs 370mpa). Easier to machine too if you draw up a design you could have someone mill something sexy. I was tempted to machine up a plate on my mill and then get it anodized but I felt like a steel plate would last longer. Not sure why though, Harkens rigging plate is ally! 

 

Yeah id mill it myself have a well equipped machine shop 

 

At some point in the future I'll do the Maths 

Edited December 8, 2020 by mtt.tr

[Paddy1000111]

On 08/12/2020 at 22:21, mtt.tr said:

 

Yeah id mill it myself have a well equipped machine shop 

 

At some point in the future I'll do the Maths 

Seems like the way to go! Only thing is with 7075 is it doesn't weld so depending how you work it, that might not be ideal.

[mtt.tr]

2 hours ago, Paddy1000111 said:

Seems like the way to go! Only thing is with 7075 is it doesn't weld so depending how you work it, that might not be ideal.

 

I would more likely down 6000series because it is weldable. 

 

But in reality plate steel works so more than likely wouldn't bother 

[Paddy1000111]

This is the same thought process I went through with steel V aluminium. Less likely to end up with micro-cracks/stress fracture in steel too. At the end of the day you're strapping it to a tree not carrying it in the tree with you, the small weight difference would be negligible and doesn't really cover the higher price of ally either. 

 

I've been thinking about making up a CAD model for the base. I need to learn to use Fusion 360 first. I learnt on the old autodesk stuff years back. Would be good if I could run a stress simulation on it. I've been thinking about the cost of creating a set of bases, getting them tested and selling a "base only" grcs which people can do what they want with. 

[mtt.tr]

Little update, i have something else that i am needing to load test so ive bought a load cell and will put together a pull test rig and test my bollard.  

 

Looking to achieve 5:1 safety factor good thing i have 2 capstans one might come to its demise 

[MattyF]

Well the winch on the GRCS is a regular boat harken 2-speed self-tailing rope winch which are around £700 depending on the model and what you want out of it. The steel which I will probably use some S275 structural will come to around £60 for some 1/2" plate, some tubing for the hinges and some angles for the brackets. The 5 tonne ratchet strap which can be surface mounted is £15. Powdercoat is £30 ish and then it's just the welding but I have a friend who will do that for a good price. The whole thing would probably set me back £800 to £900 plus testing. When I get round to doing it I'll do a guide and post up how I get on! 

Where did you find a 46 harken for £700 ?

[mtt.tr]

12 minutes ago, MattyF said:

 

Where did you find a 46 harken for £700 ?

 

 

I went for 2 lewmars not self tailing, will be converted eventually though it hasn't been an issue 

 

£70  for the pair

[mtt.tr]

Well my load cell arrived as did the amplifier 

 

Programmed the Arduino last night so i can have different load cells  different calibration factors and use one circuit. 

 

Assuming the datasheet is correct will be accurate at topend within 12kg almost certainly less in reality

 

Just need to make a case for the load cell to prevent mechanical overload 

 

 

I then had an idea which meant i could make the unit portable with an lcd will be super handy on some more involved rigging jobs basically a homemade enforcer 

 

 

 

Have a good number of pull tests i want to do.