New product for Figure 9 users

[Rapt]

I did the classic design thing for hooks its called TLAR (That Looks About Right)...

Of course it may not really be right. Size is pretty small, I made the hooks long so they wouldn't tend to dump the wrap off if they tilt. Also they get wider to the end so the wrap doesn't want to slide off if under tension. I wondered about making the 'angle' on the hooks a little steeper but didn't get around to sketching it that way.

The inner diameter of the "groove" as shown is about 2.5mm so a 3mm cord should (I hope) jam in the bottom of the groove, right at the base of the stem and hold nice and tight and its only going to be pulling about an eighth of an inch off centre so tilt should be pretty small.... Again won't know until its made, might need a tighter radius in the bottom to jam the smaller cords. and it won't take much over a .25" (5.5-6mm cord)....

The weight calc is an advantage of using a CAD system. It just has to know the density of the material and it can spit out the weight.

Strength is less simple... As usual working strength should be about 1/3 of failure strength. So about 300-500 lbs based on my 1000-1500 lb failure estimate.... If it was made from 7075-T6 then the failure strengths would be 1300-2000lb and working strengths closer to 400-650lbs...

[schrochem]

Hey Rapt,
if it's not too much trouble could you do that drawing at life size?
And printable on 8.5X11.5" (i know that's american stuff......)
That way I'll just trace it on and get 'pretty' close.
Thanks

[Rapt]

No sweat.... I'll send you the bill...

*Watch this space for the file...*

BTW you can cut out the paper pattern very roughly, and stick it (or them) to anything you want and then cut to the line to get a reasonably accurate and easy way to transfer the shape. Wood is a common choice to make a more permanent pattern, as is poly carbonate or other strong plastics.

[Rapt]

Oh and if you want to use larger than .25" rope then the size needs to increase all around... Drilling a larger centre hole signifcantly compromises strength. As will deepening the "grooves" on each side, or making them "sharper" at the bottom. If you want to do any of these things let me know and I'll readjust the sizes to compensate.

[schrochem]

No sweat.... I'll send you the bill...

*Watch this space for the file...*

BTW you can cut out the paper pattern very roughly, and stick it (or them) to anything you want and then cut to the line to get a reasonably accurate and easy way to transfer the shape. Wood is a common choice to make a more permanent pattern, as is poly carbonate or other strong plastics.

SWEET!
THANKS Rapt, that was mighty swell of ya.
I'm going to have to play tonight!

[Dutch]

Rapt which is stronger 7075 AL or 6061 AL. From what I tested WBG has the amount of tilt correct. You can draw a staight line between the load bearing side and the top hole and figure that will be the tilt. You either need a long stem, an offset stem or large hooks to compensate for the tilt. I agree the offset stem adds stress. I am going to order some Large 9s and test them. I had some but sent them to my father. WBG the 1/4 inch will be a little harder to work with, but there is no doubt it will be strong. I was amazed and how strong the 1/8 was. All the tools I used were a drill press, hacksaw, vise, dremel, round and straight files. It is incredable Rapt has a CAD file already. A conversation that start by Turk asking about this new figure 9 product turn into this.

One more thing to add; it is easy for me to use my hoist to lift the mold and get rid of slack, but in the field it is more of a challenge to get them really tight. What I learned with the three holed triangle it to pull it throught the first hole and pinch it with my thumb, then thread it though the second hole and pull it tight from the backside. There is still a little (about 1/2 inch at most) slack pulled back toward the load bearing side. So the the tightest you can get it is and tight as you can pinch with your thumb minus a half inch. I'm sure it is very simular for a knot.

[hangnout]

Rapt which is stronger 7075 AL or 6061 AL.

7075 is stronger and harder. 6061 is plenty strong and easier to machine. Make sure you get the heat tempered with the designation of 7075-T6 or 6061-T6.

[warbonnetguy]

so is the "cad file" what is needed to run a plasma or water jet cutter?

if so, i bet the cost of having them made would be alot cheaper if the machine company didn't have to write up the file for us.

i hear it's expensive to have stuff machined like that, but maybe if we can get enough people who want a set, it won't cost too much.

[schrochem]

so is the "cad file" what is needed to run a plasma or water jet cutter?

if so, i bet the cost of having them made would be alot cheaper if the machine company didn't have to write up the file for us.

i hear it's expensive to have stuff machined like that, but maybe if we can get enough people who want a set, it won't cost too much.

Well the shop behind me said they are trying to be competitive so they are going for 50/hr. They can do the file themselves, scan in a drawing, or your provide it. Of course a CAD drawing is perfect, but other files can be imported. If you stack the pieces all together in the file the cutter will just follow the lines. He did say some things about the hole diameter limitations and looking nice, etc.
If you aren't looking for 'exact' precision,etc. it takes them less time (which of course costs less money).
When I showed him the anchor type thing at the time (4 days ago LOL!) he said that would probably take 1/2 hour with prep, etc.
The price of the aluminum is small in comparison.
The aluminum I got is from ALCOA 6061-T6511

[warbonnetguy]

so a half hour to cut 1 piece?