Karver Blocks, impressions ?

http://www.karver-system.com/site/us_produits_poulies.php

Just found these blocks from Karver. Their simple design is quite impressive. Self lubricating sheaves, lightweight and as a smart person a very long time ago said "form follows function". Anyone ever used one of these ? Impressions ?

Karver Blocks are BADASS! Sadly they are ridiculously expensive and they dont really make any products thatwould be of much use on a beach cat. They are great on bigger boats though. Check out equiplite blocks too. Also ridiculously expensive boat jewelry, but cool.

BTW the smart pson you speak of was Walter Gropius, founder of the Bauhaus....

Wow, any other exotic brands and designs out there ?
Actually I am bringing this up because I just ordered some engineering thermoplastics for making some custom made blocks. Not proud at all to copy someone's else design but the Karver blocks are just simply impressive. They are expensive because of the use of PEEK thermoplastic. PEEK is 20 times more expensive than Polyacetal or Polyamide, and about 10x more expensive than Teflon (PTFE).
I'll let you know guys how will the home made blocks perform. In about 3 weeks from now.

And "form follows function" dates waaaay back, and the smart person was Vitruvius, quoted and interpreted by many. American architect Frank Lloyd Wright further developed this concept into "form and function should be one".

So, any other exotic makes out there ?

Vitruvius eh?

Thanks for the tidbit. I am a potter and was tempted to attribute that term to William Morris, but Gropius was the only person I had heard that term attributed to directly..

As to sailing related things, those two are the only exotic brands I am familiar with. Though I have noticd that Ronstan and Harken have started to to their best to appropriate the ideas w/o copyright infringement...

Use a small one at the top of the mast for the spin halyard..... Sweet

No, PEEK is expensive but still only explains a fraction of the price tag.
http://en.wikipedia.org/wiki/PEEK
My work experience lines up well with the price found in Wikipedia. I think you have to get used to the thought that the marine industry is fleecing us.

/Martin

Martin,
thanks for the link, I have already done a lot of reading about high performance thermoplastics. I will be prototyping some home made blocks in a couple of weeks.

The materials I will be using : black UV stabilized Polyacetal (55-60 MPA tensile breaking strenght, manufacturer -Ensinger), glass reinforced nylon (Polyamide 66, gf30%, 160-140 MPa tensile breaking strenght, Ensinger) and graphyte impregnated PTFE from Fluorocarbon UK.

The expected price for the test block is about 4 Euros/56mm sheave block.

PEEK (plain) costs 205 Euros/kg (VAT excluded)
Polyacetal costs 8 Euros/kg
Polyamide 66 GF30% costs 15 Euros/kg

I think the combination of expensive materials+exclusive design is what makes the Karver blocks so expensive.
I don't think they are interested in the small boat market at all.

BTW -the price tag from wiki is not at all accurate. The price I got was from industrial suppliers from Europe.

When will you accept orders? Seriously..

Rolf, testing first, if you'll like'em...I can send a few blocks for you to check out. We'll see. It might turn out as a complete failure, but I really doubt it. I have previously machined more complex parts like glass point fixings out of ss for architectural facades, and ss hinges for glass doors. So making these blocks should be easy. I'm looking forward to see how smooth will the parts move.

This is what I suspect Harken is using.


The wiki price is pretty much in the ballpark from what I have seen of finished parts delivered to our factories.
What quantities were you asking for?

The cost of design is a one-time cost...

/Martin

Martin,
You are right on the Harken blocks, I've read that in one of their data sheets, but I don't know what make of PA66 are they using. The material properties varies a lot from different manufacturers. For example Ensinger PA66 GF30% (Tecamid) has 160MPa tensile breaking strenght(dry) and 140MPa wet, while Zellamid ( Zell-Metall Austria) PA66 GF30% has 110 MPa dry.

Regarding PEEK price : I'm puzzled on this. The prices I received are for industrial quantities, from Zell-Metall Austria, Ensinger Germany and a few other manufacturers. That price is for semi-finished products like rod,tube and plates. Maybe the price you heard of is for PEEK pellets for injection moulding.

I don't know why there is such a huge price difference. Do you think you can further inquire about the price ? I'm interested to know for sure.

However, I don't think the use of PEEK is necessary because it has almost the same tensile breaking strenght as top glass reinforced PA66, which is much cheaper. PEEK is justified only for industrial aplications, for hight temps, and corroding environments.

I would be interested if you can confirm that price from a local company, but for semifinished products like rod, tube and plate.

I also suspect that Harken cheeks made out of PA66 GF30 have less tensile breaking resistance because they are injection moulded. Extruded rod should be denser and more resistant.

Different length of fibers?
Different ways of measuring?



The prices I alluded to in earlier posts are for finished parts: Injection molded PEEK part from supplier A sent to suppler B who molds high-grade silicone rubber to it (+ post curing to minimize creep). Both suppliers manufacture in Sweden.

One thing PEEK is pretty good at for being an organic material is low creep at elevated temperature. PA66 is not bad but it does not hold up well to the silicone rubber molding process.

/Martin

Measurements from different manufacturers are all conformant to ISO527, So you can pick the top product and be sure of its characterisitcs.

Martin can you clear this out for me, I didn't understand from your post : are they injecting sillicon rubber into PEEK mould or the other way around ?
It would be interesting having the block sideplates injection molded, it will save a lot of fabrication time, and much less material wastage.

The PEEK is injection molded first and then sent to the second supplier who molds silicone rubber 'ribbons' on to the PEEK part. There are a few holes in the PEEK part that will be rubber filled. This is to make sure we do not rely only on the bond between PEEK and rubber.

You may know this already but: Injection molding PEEK is a bit different from most thermoplastics in that you have heat the mold quite a bit.

I hope this helps.

/Martin