fiddle blocks, prusiks and ascenders

[asthesun]

i'm about to buy a fiddle block for use with my portawrap. my main question is which would be better to use with it, an ascender or a prusik for attatching to the line. i wont be using it personally, my groundies will and i thionk it will be about as easy to teach them either. just wondering which will slip on the rope first, an ascender or a prusik and whether this is even an issue

here's my 2 options
http://www.sherrilltree.com/Professional-Gear/Misc_7/Fiddle-Block-Kit-613
http://www.sherrilltree.com/Tree-Pulling-Kit-1492

the first says the sheaves are made from plastic which doesnt sit right with me, even though the ratings are about the same

 

[canopyboy]

I wouldn't underestimate the plastic in your first option. Modern plastics hold up very well, some seriously tough stuff. That kind of stuff has a sailing heritage, and they deal with heavy loads too. Unless you drop a giant block on it, I think it will hold up as well as any other option. It comes with the built in cam rope grab to hold it while you get another grip. That's something the tree pulling kit doesn't have. The prusik is just used to hold the onto bull rope. You could use an ascender or rope grab, but prusik is just as good and a lot cheaper in my most humble opinion.

 

[TreeClimber57]

Don't underestimate the plastic, it works. I have two of almost identical Fiddle Blocks -- https://www.baileysonline.com/itemdetail.asp?item=FB+8315&catID= (although this says Anodized T-6 aluminum frame and sheaves - But I am pretty sure there is plastic in there as well.. will take a look later tonight after I dig em out of storage bag)

These things work well.. used both of them this past weekend and wouldn't want to be with out them. There is an integrated cam cleat to hold the rope when under tension with the Fiddle Block.

They don't rust, hold up well and just keep on working. Gotta take care of your rope, but the rest pretty much stands up to whatever.

 

[TheTreeSpyder]

Either can slip,though a cam can like shred line some if it does..

If there is another prussik or cam to lock tension, realize that it usually raises the tensions, then stretch of the rest of the system, as these devices usually lock pulling out of a sheave, so, even though the system might have a 5:1 ratio on hand pull, it has 4:1 on lock/loses a leg of pull. this raises the tension of the sys, stretches the lines,a nd can shift loading some, and more likely to slip etc.

5:1 jig pull leg can also be leveraged and even sweated for more purchase of line to unloaded side, leaveing less line/ more line tension on loaded side.

Can use 2 hands properly to get 5xBodyWeight + 8xHandPull for final tightening.

 

[Ax-man]

Rope cams are hard on ropes. They can crush the fibers and create a weak spot if any heavy pulling at all is excerted on them.

Prussik knots also bite too hard for my taste and are hard to advance.

I'll pass along a tip that was handed to me on the best knot to use on line when using a 5 to 1. A Tennex endless loop tied in a beefed up version or the French Prussik or VT works the best. Holds the line very well without all the fiber crushing of a rope cam . The VT gives a better inline pull than a prussik or cam does. Getting the VT to break loose for advancing is somewhat of a pain but it doesn't lock down as hard like prussik will. I have never had a VT slip.

I have tried all the conventional ways of doing this and have found this to be the best. It is not perfect but gets the job done without the aggrivation .

Larry

 

[newb]

We have a GRCS and a Fiddle block (poor mans GRCS). There are alot of applications where we use the fiddle block. With the amount of forces that are generated with this system and the way an accender locks on the rope, I would never use anything but the prussic. Pete

 

[TheTreeSpyder]

For climbing i favor an Icicle type friction hitch, maid in Tenex, then used those old tails for some rigging too. So , did similar using eye to eye, place 1 end on host line, and have other end of eye to eye with krab for weight, and twirl quickly around host line using the weight of krab as power, and at end connect krab to other eye, to make like a long French Prussik, which then can pull down on to form like a VT

The Tenex lays flat, for more contact area, also, in laying flat it has less dimension on the deformed axis (because it is flat/about no dimension raising away from bend around tight bight of host line); so anyway, it 'stays stronger'/ has less tensile loss. A round line as prussik, would stand tall on the Turns, give more deformation/ it's inner and outer curves would be farther from each other, placing more loading on outer curve. Thus, the 'height' that the flat Tenex lacks, is taller in round, so gives more leveraged loss of useable line tensile.

In non moving Turns, flat line/webbing is better for these reasons. But, you wouldn't want to lower with flat webbing laid over a limb for support and friction, as it would get torned up, but as a hold it is better...orrrrrrrrrrrrrrrr sumetin like dat.