Toxophileken's tiller tree - tested to 200+lbs for Thimo

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Toxophileken's tiller tree - tested to 200+lbs for Thimo

toxophileken
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toxophileken
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Joined: January 15th, 2006, 4:55 am

June 7th, 2006, 4:12 am #1

This thread if mainly for Thimo, as he was asking for plans for a tree that would handle the big bows he is making.

Here is a link to one of his threads:

p081.ezboard.com/fpaleoplanet69529frm13.showMessage?topicID=3715.topic

I was thinking about trying to sell these things (in an improved version - this is a prototype); but people would just make their own, so what's the point? Besides, Thimo and Jaro were kind enough to share a device for stringing big bows, so this is the least I could do. Also, I want to give credit to Sal, who brought his tillering tree to the Simi Valley shoot where I got to use it and find out I really needed one... Please excuse the photography- some of the photos were taken in great haste some time ago.

This prototype works mounted to a wall (at home), or in a stand staked to the ground (on location).

The main beam is the cleanest, straightest douglas fir 2x4 I could find (I picked one that I could theoretically make a bow out of...). The hardware is fabricated from steel I had on hand, other than the center section of the location base, which I had to purchase specifically to sleeve the 2x4. If you can weld, the main beam could be steel tubing, unistrut, or some such, and the hardware attachments might be easier - just weld them. I used the 2x4 originally thinking that I would sell the hardware, and let people attach it to their own 2x4 (saving on shipping). If I had to do it over again, I would use unistrut, which could be purchased by the end user, and accepts various attachment brackets. I could build the hardware on to such brackets, and achieve a similar goal. Unistrut would be easy to bolt to the open frame of most garages... This would eliminate my least favorite part of my design (the wall attachment). The brackets for the handle and pulley could be pulled off the wall unistrut and put on another piece taken to locations.
If you can't weld, I think the same strength could be achieved with a little ingenuity. The top bracket, for example, could be a couple of pieces of wood cross grained and laminated and bolted to the beam. Similarly, the pulley attachment could be beefed up adequately using wood and bolts. Note that in all cases, bolts with washers are far superior in strength to screws.


Here is a photo of it in use on location:





Another, better showing how it is staked to the ground with eight approximately 18" pieces of rebar:






Here it is mounted to the wall in my shop. I have let the lower left mounting bracket swing in against the wall to show how that works. This mounting method is my least favorite part of this tree, and I would not recommend it. It is solid, and allows the bow to be out away from the wall, and the brackets aren't in the way when the tree is removed, but the mount brackets on the tree get in the way when transporting it, and making all these brackets was the most tedious part of the whole fabrication process. It took me about a week... I would have been better off thinking for 3 or 4 days to come up with a better method that would have taken one day than using the first one that came to mind. Sometimes being in a hurry just slows you down...





This picture is for Thimo, who I told I thought this tree would hold my weight. I weigh between 235-245 lbs. Here I am standing in a loop of cargo webbing that is put over the top hardware where the bow handle goes. I had to do this about a dozen times to get a decent photo, and there was creaking; but the hardware did not move or bend - so test successful, in my book. I was most worried about the mounting hardware, as I did not design it to withstand torsion (which I could easily have imparted getting on and off, but which would never occur in normal use). I didn't test the pulley, but it has a manufacturer's rating, so I didn't see the need. I feel like the hardware I fabricated to hold the pulley is much more solid than the top (bow handle holder) hardware, anyway.





Here is the top hardware and mounting brackets, with and without the cargo webbing (as positioned for the test). You can see that the wall mounts have two pins apiece that register into holes on the tree's brackets. A single pin in each is sufficient to keep the wall mounts from coming out of the tree brackets, though all the pins are drilled. All forces during use tend to pull the tree away from the wall, so this (what I consider) delicate mounting system is plenty strong, if complicated. When the tree is removed, the wall mounts swing down by gravity to hang inside the wall frame of 2x4 studs. Each pair of mounts is held in place by a 3/8" bolt through a wall stud. Extra wood is screwed to the stud to support and surround the extra length of the bolts, only to help keep them from bending (though unlikely).






Here are a couple angles of the top bow handle holding hardware, with and without the removeable wood pieces (discussed and shown below). This bracket was fabricated from a 2" piece of angle iron, 1/8" thick, with small triangular "webs" added for strength. The bracket is mounted to the 2x4 using six #8 size bolts. Though obviously strong enough, this is easily the weakest point in the system, and I am, frankly, shocked that I did not wrap the metal of the bracket around the wood to give additional strength, as I did in the pulley bracket shown later.
The ruler is placed such that the measurement of draw length is taken to the grip. It is off center so that one edge is centered.
The eye screw simply gives a place for the string hook and scale to hang when not in use.
The slots are to allow the wooden part that holds the bow from slipping sideways off the bracket to be adjusted for grip width.
The holes are to accomodate dowels in various wooden grip supports, that can be interchanged to accept different shapes of bow handles, if necessary ( it rarely is):





Sideview of top hardware, and the bow grip support block and bow retainer piece.
Note that the vertical member is offset so that it can easily flipped around to accomodate a wider range of grip sizes. The bow grip support blocks are all cut so that the ruler is accurate measuring draw length to the grip. Sorry I didn't show the other shapes, but you get the idea... Various curved shapes to slip into more dished handles. I usually just use this one, anyway- and if one side of the handle slopes (tilting the bow on the tree), I just shim it up with scraps of wood. What I am saying is- a lot of work for little benefit...





Lower wall mounts, in place, and with one retracted:





Two views of how the pulley is mounted to the beam, also showing the brackets on the tree that accept the wall mounts:





Two more similar views. I had to cut out a recess for the back of the pulley, which has a hole to accept a 3/8" bolt. I fabricated a bracket to give the wood additional support, and used a hardened bolt. I thought this necessary since I had removed so much wood to receive the back of the pulley. A better view of a similar pulley is shown later:





Here is a photo of the same type of pulley (on another protype archery related device), and a photo of how I adapted a scale for this tree.
The pulley is rated at 525lbs, but I saw a diagram that showed you effectively double the weight you are applying to the pulley when used as in this configuration (approximately 90 degrees to load). Even so, this is still more weight than I tested the top bracket with (262.5lbs vs @240lbs).
The scale I had lying around. They are fairly cheap, and are not especially accurate at the low and high end ranges. Mine comes in about 2-3lbs light in the midranges (40-60lbs). The scale on the far right shows the aluminum pin that holds the innards of the scale inside the main body (tube). I drove it out and found that a piece of welding rod (3/16" or 1/4") I had fit perfectly- so I welded together a replacement piece with a loop for a string. Not pretty, but it works. Hmmm. What was I saying about weakest point in the system? The string used is military surplus "parachute cord". It has a nickname that indicates the number of internal strands and the rated strength, which I can't remember... (Andy just bailed me out- it is "550 cord"... Apparently 550# rating. I was wrong about the strands...)





I welded shut the open loop on the scale and use a "quick link". Pretty much a waste of time, except it is easier to hang up when not in use. One more thing to lose, though...





Ok, my very favorite part of the whole thing! I don't know why, but I just love it. A retractable carpenter's pencil attached on the back of the tree at the top - to mark tillering notes on the bow with. Cost more than it is worth (at Home Slomo), but everytime I use it, I have to suppress chuckles...





Here is the base for locations. The specific size of metal (@1/8" thick walls, 2" x 4" (ironically) outer dimensions, @3 5/8" x @1 5/8" inner dimensions, by 18" tall) cost about $10. Not that much money, but expensive compared to other steel tubing I have bought. The bolts with the knobs hold the tree in place, and allow me to level the main beam slightly if the ground is a little off. Not much adjustment there, though.
Originally, I welded the legs onto the base. What a great metal "albatross" in my car, though - with a wingspan of about 42". Very inconvenient, even in a van or motorhome! I cut off the legs, and found some tubing lying around that sleeved over them nicely. They are welded in place where the legs were, and only stick out about 3". The four legs are about 19" long.
I got very lucky with the size tubing I used (vertical supports cut out of a metal fence section salvaged from a photo set) for the legs - I didn't plan it, but when I cut them off I found that they sleeved perfectly back to back and side to side inside the main base tube... Praise God!
The reason it is painted so garishly was to avoid people tripping over it in the dark at camp-over archery shoots. I had planned to remove the tree at night to keep it out of the weather, but I decided that with all that metal so firmly staked to the ground, an injury was likely... Now I just leave the tree in place at night, so people just get a light face smashing if they walk into it, rather than an impalement...





Two views of the ends of the legs, that take the rebar stakes. They are of the same tubing as the legs. I welded them on at opposing angles to each other, for greater strength when staked in place. Eight rebar stakes may be overkill... It hasn't moved on me so far.





While I am posting photos, here are some easy to make, portable and light benches I made for location (but I use them all the time at home). I bought a pair of folding metal sawhorses for about $20, cut the legs off the saw horses, and cut some length off the legs to shorten the benches to a comfortable height (about 24").
The best part about them, to me, is that I spent twice as much on the wood and bought some well dried redwood instead of the green, heavy douglas fir they have available everywhere these days. They are much lighter than they would have been; and they are holding up to my bulk nicely, so they must be plenty strong...
I had been planning on making a shaving horse, but Tim Baker told me to just attach a vise to a bench. I took his advice, and haven't looked back. The speed vice I have is very handy, but I don't know where to buy them. Fortunately for me, Greg gave me another one, so I have one for each bench (thanks Greg!), and I can share one with other people at events. I put a spare piece of wood under the vise to raise the staves up on top of my leg, for support when removing wood.





Alright, another marathon post from Ken. Hope it helps.

If I was going to make this specifically for very heavy bows, like Thimo is talking about, I would beef up several areas: the top bracket, and the scale/rope connection. I might consider (vinyl coated)aircraft cable for the rope, as well. I would also consider using steel tubing for the main beam (if a steel beam was used, the top bracket is plenty strong). Remember, in wood or steel, beam strength is stronger pulling (or pushing) on the long legs of the beam (i.e. 90 degrees rotated from how I have my beam). So, a rectangular tube beam, putting load on the long legs, would be stronger than a square tube beam (whose sides were equal to the short legs of the rectangle).

I feel confident that a person who doesn't want to weld and fabricate steel could come up with something similar out of wood that would work just as well. Remember, triangles add strength to your design (like the webs on my handle bracket). A wood base might need some triangles, for instance.
I would use a better scale.
Remember to make your tree tall enough to accomodate your scale, at any drawlength you might want. My tree is 77" high, and the pulley is 48" down from the grip of the bow. My scale is 13" long, including the quicklink and metal loop that holds the string. Some of the better scales are probably longer...

Good luck!

Ken
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Thimosabv
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Thimosabv
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Joined: December 25th, 2005, 5:03 am

June 7th, 2006, 10:25 am #2

Ken, as a kindred visual thinker, THIS ROCKS!

Man, with all the spot on pics, you made the construnction as simple as apple-pie.

Thanks alot.


Where were you hideing your blasted camera all this darn time?????
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Win1885
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Win1885
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Joined: May 5th, 2005, 7:53 pm

June 7th, 2006, 11:22 am #3

That's a super tiller tree! I noticed it in another thread and was going to suggest a build-along for it....Thanks! Perhaps you couldn't sell the whole unit, but I'd be interested in a price on the hardware.....including the base for outdoor use.
Most guys could supply their own 2 x 4 and do the woodwork.
Mine's not a sophisticated and can only be used in my shop. The tree is attached to a wall stud in two locations. I glued and screwed 2 ea. 1/2" thk plywood pads to the back of the tree that extend out of the left side of the tree about 2 inches. The extensions are then screwed into the stud. The cleat is just to hang everything on when not in use and to wrap the pull rope around when tillering.

Tom I.
Duh! I looked at your pictures before reading the text. Sorry for the redundancy.
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tomasaf24
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June 7th, 2006, 4:15 pm #4

The nickname for your parachute cord string is "550 cord". I don't know about the number of internal strands, but its tensile strength is 550#. It's strong but stretches quite a bit.

Andy
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toxophileken
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toxophileken
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Joined: January 15th, 2006, 4:55 am

June 8th, 2006, 6:21 am #5

Thanks very much, guys!

Thimo, it took me forever to get around to learning to post photos on this site. Once I finally sat down and spent the time to figure it out, it was no big deal. I still find it much more tedious than chasing a back ring...
The main problem is that I hate to take bad photos even more than I hate to make bad bows. I am working on making better bows; but as a photographer, I have no excuse for shoddy photographs, and even quick and dirty photos are sometimes hard for me to accept from myself. It is hard to get excited about taking pictures that don't make my soul sing, I guess I am saying... So consider all those I have posted as a small labor of love for you guys...

Oh, and Thimo, there was some hesitation on my part- "Who am I to show how to do anything?" It is because of guys like you and Manny and others that I had the courage to try and share my small offerings...

Tom - I like your tree, especially the way you turned your beam for greater strenth. I am glad you were thinking the same way I was about that, and selling the hardware. If I was going to produce any of it for sale, I would have to give the fabrication process (as in: ease of and efficiency) some serious thought. I would probably base the upper hardware and pulley mount reinforcement bracket on the same rectangular steel tubing as the center piece of the location base, to eliminate several steps. I would also have to come up with a more simple handle keeper.
If enough people showed interest, I would think about making a bunch at one time; but doing it one at a time is a drag...
I still like the unistrut idea... I would, of course have to modify the base; and the hardware would get more expensive... But not prohibitively so. It would allow you to simply take the hardware off to go with your other piece of unistrut to locations, as I said. Also, it might mean I could do almost everything with a welder - less drilling, etc. It is much faster, for example, to just zap the pulley to a metal bracket than to drill holes for a bolt...

I guess I could make some similar bases, if enough people are interested.

Andy, thanks! That was going to drive me crazy... I am going to put that in the main post right now!

Ken
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