surveyor

speaking of versions, I have added a swivel lock link on the upper arm of the Bulldog Bone.

Ha! Not to worry, my kids prefer a doubled line.

Yes you can put a pulley on the bottom arm.

Well, the two arm OAR that Bing! has, self advances. The Bulldog Bone tends slack better without an added pulley and is more of a SRT device, although it works fine DdRT as long as the standing part of the line is clipped into the bridge, but you have to advance and then manually take up slack. At 12 oz. the Bulldog Bone is about 10 oz. lighter than the three arm OAR. The Bulldog Bone also does not use rollers, however a small 1/2 inch roller can be added to the top arm to make it a bit grippier.

I continue to build ascender/descenders. This one I call a Bulldog Bone and it seems sweet, with many nice attributes. Here it is in action with my 165 lbs. on Imori.

Thanks Bing! for the pictures and review. The OAR can be dissembled and cleaned with a wire wheel if so desired. This video shows my latest OAR with a spring on the lower arm to make it "stick" on rope when transitioning from ascent to descent (applicable mostly SRT), because the top two arms use 5/8" rollers, it will likely release on a DdRT setup with all three arms engaged with the Imori, by pulling the bottom arm all the way down (disengaged). One of the very nice features of the OAR is the very negligible sit back when ascending. Bing!, do you work in sappy conifers much? Is the OAR sticky on release if it gets pitchy? Thanks to my son Dean for helping with the video.

Thanks Old Mill. BenR, it self tends well with some rope weight below. The spring is actually just strong enough to make it "stick" when transitioning from ascent to weighted. I have machined rope size grooves on the inner edges of each arm which helps ease the rope through the OAR, of course it depends on the rope size and stiffness. The rollers are 1/2" wide, so it is made to accommodate that size rope, but works for me on Rocket line, KMIII, Imori, Tachyon, and Yale XTC. It creeps with Velocity on a doubled rope with my weight. Because the top two arms swing down to the bottom release arm, it manually tends slack quite well, and advances nicely when pulled along on ascent. Perhaps Bing! can comment on how his two arm OAR is working out on a doubled rope. Here is a video of the two arm OAR tending slack with a bit of weight below.

I have made a functional improvement to the Bulldog OAR by adding a spring to the lower arm. Thanks to my son for helping with the video, and for all who have commented on the Bulldog OAR.

The Bulldog OAR is still a work in progress. As I receive feedback I try to make improvements. It is likely that it would be improved by spring-loading the bottom arm, so that it "sticks" as it transitions from ascending to descending, especially on a narrower rope. Being biased about the OAR I am awaiting further feedback from some seasoned arborists.

I continue to work on the OAR, and believe I have made an improvement, both to the way it fairleads, the smoothness of release, the grip on rope, and it is slightly lighter then my other three arm OAR. The video shows a working mule, I plan to add a beefier spine once I receive a material order. I do not show in the video, but I have machined a groove on the inner part of the arms in order to ease the passage of fatter ropes through the device. It likes my Yale half inch rope, and works also with my weight on Imori, tachyon, rocketline, and KMIII, it creeps only on velocity. because of the cantilever bottom arm, the grip there is more proportional to the climbers weight, as it will release for my young son with his light weight also. This OAR also will self tend with KMIII and Rocket line when there is little or no weight on the hitch attach point. I hope to receive feedback from a gathering of arborists who I am sending a demo unit to in Florida this coming week.

It would be interesting to tether the Zillion above the zigzag (like a RW) on a single line to see if it would do SRT.

Thanks, The rack is made from standard steel roller links (ANSI rated at over 14,000 lbs breaking strength). basically I used half the rollers as the standard roller chain, in order to make room for the rope to pass through the device. Each master link has a side plate with a spring steel clip which engages with slots in each pin, which allows the bottom link to be attached to the top hole in the hitch climber pulley. The headstock is my own design. Personally, I think the OAR is superior because it has almost zero sit back, and is mid-line useable, and the very durable steel links are easily replaceable.

Tried the OAR to see if it will self tail with my orange Tachyon with a bit of weight on the tail.

The pulley/rack I made (before the public release of the ZZ) was actually intended for SRT use. I have tried it low on a doubled rope, but since the headstock faced the standing part of the rope it was a bit awkward with my longer headstock. I have not had it high enough to answer your question about it self tailing with rope weight below. [ame=http://www.youtube.com/watch?v=8czYPRuL8t4]demonstration video of pulley/rack - YouTube[/ame]

Here is an OAR set up for a doubled rope with O rig. I am trying to tidy it up a bit by using the spliced eye on the shackle, with a beeline eye and eye attached directly on the top link, and the other end on the shackle pin below. The advantage with the OAR, as I see it this way, is that the OAR does not need a biner nor a pulley (the hole on the bottom arm is for a roller with quick release pin for an axle if desired). Also it has virtually no sitback and slack can be tended nicely if limb walking, by self advancing the OAR above yourself by pulling the slack down through the OAR. Did I mention it is midline attachable also : )

That looks very well setup!

Here is the OAR in an O-rig configuration (single action biner for demonstration only). If the standing end of the rope is threaded as shown, between the top arm link and top attach point, then down through the biner, it creates a small bend in the standing line which holds it in place, much like a prussic. The OAR can then be advanced completely out of reach if so desired, as long as you have a tether on the slack tending quick release pin. (thanks to Thomas , Justin, and Brian for their input for this idea )

This is such a shame, as this may turn people off to mechanical descenders. Especially since, in my opinion, it is the sharp edge on the half circle edge of the bollard that is doing the damage to the rope, as the rope is flattened running through the device riding up unto that edge.

There has to be a somewhat sharp edge somewhere doing damage like that. When I was first making my pulley/rack, the side links were making a similar but less severe damage to my Yale XTC. After I rounded the edges it solved the problem. You will likely always see some flattening of the rope however.

No one seems to know how long it will last, but based on the number of friction points compared to the SJ, I would guess it will start to slip on 11mm rope after about 2 years.

reminds me of this spiral stair.

The spacer I had was the narrower one (1/2"). It may cause problems with uneven wear as I noticed the spacer was quite warm to the touch even after a very short use.

When I met with Paul at the Charlotte event last year, and he was showing his prototype HH, I did in fact lend him a DMM spacer to see how it worked at ground level. While the HH did descend with the spacer inserted, as Paul tried low and slow, I don't think it was that much different than the slack tending around the radius of the biner itself.

Old Mill, I can make one for you now. PM me and we can discuss the details. Thanks, Gordon

Here is a short video demonstrating the use of the adjustable anchor point Bulldog OAR. I first set it up to creep online SRT with my weight, then adjust the anchor for more grip on the KMIII rope, and ascend a bit to demonstrate how it releases. Then I change over to DdRT to demonstrate two ways of using it in this manner. I did not note in the video, but you can also take the top arm completely off, if you are using the OAR with DdRT only. [ame=http://www.youtube.com/watch?v=MXT0gKdmthk]adjustable grip Bulldog OAR - YouTube[/ame]