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Saddle trees and changing back shape
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Tammy 2
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 Posted: Thu Jan 21st, 2010 01:43 am
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Hi Adam,

I find these very interesting.  My horse showed a marked change between the ages of 5, 6 and even into 7.  No height growth really, more like the final "filling out".  His back changed just like Tindur's has and appeared longer and more raised.

Also I think his back looks like he has been ridden very well and he has been using his core.

 

Carey
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 Posted: Tue Jan 26th, 2010 10:37 pm
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I agree, I think most horses continue to develop muscles until they are at least 8-- and even longer if they are in a good program.  That has been my experience.  With the type of horses I have the difference between a 3 yr old and an 8 yr old is huge. 

AdamTill
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 Posted: Wed Jan 27th, 2010 05:44 am
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Thanks folks...live and learn I guess.

Making progress on the tree design. Dave or Dr. Deb - if either of you have a minute, I'd be curious to hear your thoughts on how much clearance to allow between the scapular cartilage and tree.

The dark green horizontal lines are the saddle fitting range extents - the topmost one is the edge of the scapular cartilage, and the lowermost one is about where his last rib is.

I'm taking some educated guesses at this point, but I thought I'd do up a cardboard skeleton tree and take it out to my horse to test. I figure if I do a bit of playing around on the ground and it stays more or less in the same spot, I should be pretty close.

Not sure if this mess will make sense to anyone else, but displaying three dimensions in two is tough. The profile lines on the far right are like longitudinal vertical slices though the horse at the same point where the corresponding line passes through the cross sections on the left.

The first thing I'm working with is the the midline of the bar - how the profile of the back in red compares to the profile of the bar in green. The tree itself is just a graphic for now - something to use as a visual reference only.

Cheers all,
Adam


David Genadek
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 Posted: Wed Jan 27th, 2010 10:19 pm
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Adam,

Welcome to the nightmare!

     When I was first trying to define the shape I used a plaster cast and made a cinch that went over the area where I would sit. I secured it in place  place and had the horse do figure eights well everything dried. Now what I do is use the exact same technique you're doing except I try to capture the shape in all the different postures that the horse would make. You can bend the beast around a barrel and lifts a leg and then take your tracings and then do it on the other side. You also want to capture the shapes with the head up and head down. As you can already see things change a lot!!

How is the tree that we did for your beast working with his new shape? This is one of my biggest gripes narrowing the bars in the center of the saddle if you keep it as wide as possible as angles and things change it seems there is generally enough contact so that the saddle will not bother the animal.

This is a great exercise for everyone to do if they want to get a handle on the reality of saddle fit here is a link to instructions on how to do a back map. http://aboutthehorse.com/web/tracings.pdf

AdamTill
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 Posted: Thu Jan 28th, 2010 02:07 pm
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Thanks, yes!...so much to think about here. I'll play a bit with a few more orientations.

I got a great idea from a fitting course I took with Dr Ridgeway a little while ago, who suggested joining two sticks at one end, and suspending one of those blue flexi-rulers between the other ends. Makes using the flexi-rulers much easier and more accurate! I made mine from round aluminum barstock, added a gentle curve to accomodate barrel curves, and added a wingnut in the center to allow the bars to be locked together. Works a treat.

You actually didn't do a sadddle for this critter, who I only got about a year ago, but for my last guy. His new owner is still using one of two I had (kept the other), which is going on 5-6 yrs total for that saddle I think, but that horse is now about 16 (hopefully stopped growing). If this project doesn't turn out, I'm sure I'll be calling later!

Dimension-wise, if you you were to be doing a ranch roping saddle, what material do you use for the bars, and what would the thickness be at the stirrup notch in the middle? I'd like to make my bars from carbon fibre later on since that's SO much easier to use in complex shapes, and need to do some stress calcs to figure out a layup schedule.

Thanks again!

Adam

Patricia Barlow Irick
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 Posted: Thu Jan 28th, 2010 09:00 pm
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The tracings PDF is really great. I like the tape much better than the chalk markings most instructions tell you to use.  I want to try it when my critters dry out.

This fall I bought an impression pad to check saddle fit and started really thinking about the "nightmare". Yikes!!! I wanted to make a tool to quantify shape and then realized it had already been made as the Lauriche Back Measure . They didn't make many of them, but I think it is not too big of a engineering feat that a three pieces of plexiglass or aluminum plate and some dowels couldn't be pressed into service. It would be fun to play with.

There was a recent article in one of the major horse journals by a doctoral student studying swaybacks. He used an interesting measure to classify horses backs. "The high points of the horse's withers and the rump are marked with adhesive tape, and the straight-line distance and the back-surface distance between these two points are measured and compared. The difference between the two lengths serves as the back-contour measure." A difference of over 2.5 was classified as swayback.

This measure surprised me as it would mean minis would be less likely to be swayback than drafthorses simply because of their size. I would think he would use a ratio.  But I guess I need to read the research paper to understand what really happened.

I like your first graphics (on white background) Adam, but I find the black background one more confusing and less interesting even though it has more relationship to the tree. I would like to see a contour map of the bottom of that tree. Keep up the good work!

Yrs,
Patricia


AdamTill
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 Posted: Thu Jan 28th, 2010 11:40 pm
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>The tracings PDF is really great. I like the tape much better than the chalk markings most instructions tell you to use.  I want to try it when my critters dry out.

Tape is very good, but long runs of tape tend to crinkle, so be careful. A builders chalk snapline is sort of handy for "station" lines since you can run a straight chalkline pretty easily.

>This fall I bought an impression pad to check saddle fit and started really thinking about the "nightmare". Yikes!!!

That's the sort of doughy-filled one, isn't it? They're okay, but they're thick enough to change the fit of the saddle, and ironing them out flat again is a pain.

Much easier is to get a refill bottle of builder's chalk, and a simple white dressage pad. Sprinkle and spread an even dusting over the horse, then carefully put the pad and saddle on top. Find a fence to get on the horse so you don't need to weight a stirrup unevenly to get on, ride him, and vault off. When you carefully lift the saddle and pad straight off, you get a great pressure map. Another good trick from Dr. Ridgeway.

>I wanted to make a tool to quantify shape and then realized it had already been made as the Lauriche Back Measure . They didn't make many of them, but I think it is not too big of a engineering feat that a three pieces of plexiglass or aluminum plate and some dowels couldn't be pressed into service. It would be fun to play with.

I looked into making one, but the tolerances involved are actually pretty tricky if you don't want wabbly, useless dowels. Plus, using them consistently is tricky, and translating the data is quite time consuming.

>There was a recent article in one of the major horse journals by a doctoral student studying swaybacks. He used an interesting measure to classify horses backs. "The high points of the horse's withers and the rump are marked with adhesive tape, and the straight-line distance and the back-surface distance between these two points are measured and compared. The difference between the two lengths serves as the back-contour measure." A difference of over 2.5 was classified as swayback.
This measure surprised me as it would mean minis would be less likely to be swayback than drafthorses simply because of their size. I would think he would use a ratio.  But I guess I need to read the research paper to understand what really happened.

That seems odd, for sure. I measured one of the photos of Tindur, and he was 31 inches along the back and 29.8 inches straightline. I assume they use inches? Weird system...I agree that a ratio would be much more appropriate, though I guess if they're fixing height or something you could call that a control.

>I like your first graphics (on white background) Adam, but I find the black background one more confusing and less interesting even though it has more relationship to the tree. I would like to see a contour map of the bottom of that tree. Keep up the good work!

It's actually there already - just a tricky drawing to interpret, and one that isn't finished yet.

Picture the left side drawing with the bar top view as being your main view. The grey and dark green lines are station or section lines...vertical slices taken crosswise. Those sections are the pink cross sections. The pink cross section meets the station line that it represents right in the middle.

As such, my first approximation of the bar angles are the green lines hovering over those pink cross sections. I think I'll probably be flaring the shoulders a bit more, and the bars won't obviously be flat lines, but you get the picture.

The back profile lines (same thing top and right, just rotated on the top for easier perspective) describe a vertical cut lenthwise through the saddle/horse. So for example, if you go back to the left drawing with the light blue bar top view, look at the orange lines that are outermost on the drawing. If you were to slice the horse lengthwise along that line, then look at it from the side as if he were standing up, you'd get the orange line on the back profile lines plot.

In the same way, the red line on the profile lines plot is the back profile right under the middle of the bar. The green line is the profile of the bottom of the bar itself, so you can see how much rock is being considered for that bar.

Not sure if that makes sense, but drop a note if it doesn't. I'll update the drawing as I make progress, and actually show complete bar cross sections and such.

Cheers,
Adam



Patricia Barlow Irick
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 Posted: Sat Jan 30th, 2010 03:28 am
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That's what they say about the Lauriche tool, but who knows if it is true? What attracts me to that idea is having a bunch of quantitative data.

DrDeb
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 Posted: Sat Jan 30th, 2010 08:46 am
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Patricia, beware: no curving shape can be specified by any number or measurement whatsoever.

Nor by any formula.

There are no formulas within mathematics, or known to even the greatest scholar, which precisely specify ANY curving figure as we can specify squares, rectangles, polygons, or triangles.

ALL mathematical formulae that pretend to specify curving figures are doing exactly that: pretending. For example, the wellknown formula for a circle:

Pi X radius X radius ("Pi R squared")

-- this formula was "discovered" by ancient Egyptians, as you have probably read, and it worked well enough to allow them to order the right amount of lumber to build a roundpen. Within a foot or two. But it DOES NOT precisely specify. The reason for this is the so-called "irrational" number incorporated into the formula, the term Pi, given in short form 3.1415 as we were all made to memorize. And even recently, I read a news article that a supercomputer somewhere has calculated Pi out to a billion decimals, and it still does not "close".

Which precisely makes my point: it does not close for a billion digits and my bet, along with that of most mathematicians, is that it will never close. Pi isn't even a limit function which gets closer and closer to precise specificity the farther out it is calculated. Pi is, instead, in a class by itself -- irrational numbers. Another word for an irrational number is "fudge factor". Pi is the "fudge factor" that the ancient Egyptians discovered was needed to make the lumber order come out right.

It is apparently not allowed by the design of the Creator, that we have access in this plane of existence to any formula that precisely specifies a curve. All the formulas you learned in algebra II that pretend to specify parabolas and hyperbolas are, in fact, limit functions. All the limit functions you studied in Calculus are no more than various forms of the Giant's Stairway Conundrum, where you keep dividing the steps up by halves that keep getting closer and closer to "getting there" -- but never do actually get there. A mathematician of the second class may scream at this and say, yes but it gets INFINITELY CLOSE to getting there; to which I reply, yes, and who made up the definition of 'infinitely close'? He-for-whom-it-is-convenient, that's who.

Even Benoit Mandelbrot's chaos equations, elegant though they are, fall into this category. In graduate school I was positively in love with the idea that you could describe the irregularly curving, yet somehow logical shapes of bones by visualizing them as glass jars filled with golf balls, marbles, peas, and grains of sand....but once again, all those are is a sort of visual histogram-under-the-curve, a cousin of the Fourier chain, a cousin of the limit function.

We cannot get there from here. My belief is that when we die, like the folks in "Flatland", we will be permitted, like them, to go up into a higher dimension where (the Flatlanders) finally get hands-on experience with geometric solids, and where we (who can already experience those in this plane of existence) get to have access to equations that precisely specify curving shapes. This will be the same moment when we have a fully integrated theory of physics, where we can really travel at warp speed (or something even better, have physical existence simultaneously at any number of points we choose), where light itself will be to us as a solid and something greater than light will be light to us.

Shy of that, however....until we get there....you have to design saddle trees, as well as fit them, "by eye". There is no other way. You have to develop your ability to "see" it, to feel it, and to know by this means whether or not the saddle sufficiently and appropriately conforms to the shape of the particular horse's back, so that we can say it "fits". You will please not forget that your brain is a supercomputer vastly, almost infinitely, more powerful -- particularly for shape processing -- than any manmade tool.

I am advising you to learn to use the equipment you HAVE. How to do this was already set forth by our elderly teacher:

OBSERVE

REMEMBER

COMPARE

....and in this, our elderly teacher is only repeating the teaching of the first great Western scientist, Galileo Galilei.

"Not everything that can be counted counts, and not everything that counts can be counted." -- Albert Einstein

David Genadek
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 Posted: Sun Jan 31st, 2010 06:32 pm
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Adam,

     Designing a tree requires a series of compromises that depend on a multitude of factors, there is no one right answer to your question because it depends. What we can talk about are the factors that need to be considered.

      First, where on the horses body do you want the saddle to sit. This is one of the most in important decisions that is made in the design.  This is where doing a bunch of tracings comes in handy because it allows you to begin to understand where the majority of the movement is.

     Second creating the shape of the bar to allow for the movement of the back relative to where you decided you wanted to sit. This is where most people go wrong they only consider the static back. The old Zen saying "You can't step in the same river twice." applies here.  You're not fitting a shape your fitting a collection of shapes if someone were to say fit the shape of water everyone would consider that ridiculous.  This is the real value in trying to collect data on horses backs what you soon realize is each horse has many backs and one of your roles as a rider is to create the shape of back you need to execute whatever maneuver you choose. So when you go to design a bar you're trying to design the shape that will allow for the composite shape of the horses back in movement. This seems to be a very difficult concept for people to grasp. When I first started this company and it was 50% owned by Crates Leather Company we did a line of ladies trail saddles under the Crates name and sold them to retailers. Many of the retailers got upset saying they did not fit because there was no pressure on the front of the saddle.

    Once you get the horse fit you now have to consider the interface of the human.  We actually made 3-D models of butts at this stage.  Here is how you can get your answers to  the question you asked.  It shouldn't be a very difficult answer to find for an individual horse. What I would do is get some sort of material in various thicknesses and cut them in the shape of a bicycle seat and I would put them on the horse where I wanted to sit and find out at what thickness I felt the best on this particular shape of horse. Once I had that figured out I would take that overall thickness and subtract the thicknesses of my saddle components and that would leave me with the desired bar thickness relative to rider position for this particular horse. I would then have to compare that to my saddle construction needs.   In the case of this horse you're going to find a conflict between the shape of the animal and the shape of the human so compromises will have to be made.  A narrow feeling seat can only be accomplished by going up so you will need to decide if you want to  go up by bar thickness or by how you construct your ground seat. The skirt construction will come in to play at this point of your decision also.

As for materials, here again it depends. When you say you want to use carbon fiber are you talking about carbon fiber an balsa wood as in how they do floors of expensive cars? Are you talking about making the entire tree out of carbon fiber in which case you probably end up with a really heavy tree. The main thing to consider is attachment strength. Although the fiber in the resin will offer some holding power you will probably want to find a wood with better holding properties.  I use basswood in my trees as it is light and readily available here but I add strength to it by covering all the parts with epoxy resin. I laminate everything for added strength too.  What I have found is tree makers generally will tell you the best wood  is what they can get in their area at a reasonable price. I laminate everything for added strength too. Here again your choices are going to depend on what your specific needs are. If I was building a ranch roping saddle and I knew I was going to be roping great big huge steers on a regular basis I might choose different materials. However, if you're going to use resins and carbon fiber, the only real value the material is going have will be its ability to create the shape and anchor attachments.

David Genadek

David Genadek
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 Posted: Sun Jan 31st, 2010 06:37 pm
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Adam,

 

I'm not sure if you have the most recent version of Adobe Acrobat but if you do you can save the file as a 3-D PDF and anyone with Adobe reader would have the ability to rotate the drawing.

David Genadek

David Genadek
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 Posted: Sun Jan 31st, 2010 06:43 pm
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Patricia Barlow Irick wrote: The tracings PDF is really great. I like the tape much better than the chalk markings most instructions tell you to use.  I want to try it when my critters dry out.

This fall I bought an impression pad to check saddle fit and started really thinking about the "nightmare". Yikes!!! I wanted to make a tool to quantify shape and then realized it had already been made as the Lauriche Back Measure . They didn't make many of them, but I think it is not too big of a engineering feat that a three pieces of plexiglass or aluminum plate and some dowels couldn't be pressed into service. It would be fun to play with.

There was a recent article in one of the major horse journals by a doctoral student studying swaybacks. He used an interesting measure to classify horses backs. "The high points of the horse's withers and the rump are marked with adhesive tape, and the straight-line distance and the back-surface distance between these two points are measured and compared. The difference between the two lengths serves as the back-contour measure." A difference of over 2.5 was classified as swayback.

This measure surprised me as it would mean minis would be less likely to be swayback than drafthorses simply because of their size. I would think he would use a ratio.  But I guess I need to read the research paper to understand what really happened.

I like your first graphics (on white background) Adam, but I find the black background one more confusing and less interesting even though it has more relationship to the tree. I would like to see a contour map of the bottom of that tree. Keep up the good work!

Yrs,
Patricia



Boy, I sure hope that guy didn't get a PhD for that research.!!!! If you have accurately described what his intent was it's crazy!!!

There always seems to be a constant flow of new measuring devices. I have found that gaining an understanding of horsemanship has been of far greater value to me than all the measuring I have done. So much of the research on saddle fitting is measuring bad riding and has nothing to do with the saddle fitting or not.

David Genadek

 

AdamTill
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 Posted: Mon Feb 1st, 2010 06:51 pm
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Hi David,

Thanks again for the reply. To your questions:

>      First, where on the horses body do you want the saddle to sit. This is one of the most in important decisions that is made in the design.  This is >where doing a bunch of tracings comes in handy because it allows you to begin to understand where the majority of the movement is.

When I was first looking into saddle design and fit before, I took and measured some photos of one of the saddles you did on my old guy. I quite liked where the saddle put me, and he seemed to get along with it quite well as well.




On my new guy, I'm dealing with quite a bit of a shorter fitting range, but I assume the principles stay the same. I Opted for the shortest bar I think I can get away with, and started with an attempt to center my weight in the middle of his back. That places the back tip of the bar just at station 6 (last rib, thereabouts), which I think is about right. The red center of gravity circle is about where I figured my seatbones would end up.



>     Second creating the shape of the bar to allow for the movement of the back relative to where you decided you wanted to sit. This is where most people go wrong they only consider the static back.

I'm doing my best to try to avoid that. I'll do my best based on the data I've gathered so far, then I think it'd be easy enough to knock together some cardboard trees to take out to my horse. Depending on how they fit and move, I should be able to see if I'm on the right track.

>    Once you get the horse fit you now have to consider the interface of the human.  We actually made 3-D models of butts at this stage.

I spent a few weeks playing around with reshaping the seat on the saddle that I have right now, since the original one was WAY too deep for my liking (dressage saddle). I think I have a good feel now for what's balanced and comfortable on my end. I also got an appreciation for how a seat that's too padded/squishy is actually much more uncomfortable for riding in for more then an hour. The lack of circulation as a result of constant pressure gets things a bit achy (which is a good argument against air panels and such for the horse, too).

>Here is how you can get your answers to  the question you asked.  It shouldn't be a very difficult answer to find for an individual horse. What I would do is get some sort of material in various thicknesses and cut them in the shape of a bicycle seat and I would put them on the horse where I wanted to sit and find out at what thickness I felt the best on this particular shape of horse. Once I had that figured out I would take that overall thickness and subtract the thicknesses of my saddle components and that would leave me with the desired bar thickness relative to rider position for this particular horse. I would then have to compare that to my saddle construction needs.   In the case of this horse you're going to find a conflict between the shape of the animal and the shape of the human so compromises will have to be made.  A narrow feeling seat can only be accomplished by going up so you will need to decide if you want to  go up by bar thickness or by how you construct your ground seat. The skirt construction will come in to play at this point of your decision also.

Good points...will have to do more pondering, thanks much for that.

I anticipate doing the ground seat the same way as the bars - make a postive mold form, then vacuum bag on top.

>As for materials, here again it depends. When you say you want to use carbon fiber are you talking about carbon fiber an balsa wood as in how they do floors of expensive cars? Are you talking about making the entire tree out of carbon fiber in which case you probably end up with a really heavy tree.

It would be the former. When I build aircraft wing spars, the method involves carbon caps, vertical grain balsa webs to carry the shear loads, basswood or sitka spruce hardpoints where fasteners pass through the spar, and a kevlar wrap for burst resistance. I'm imagining the bars as short fat spars.

The advantage of c/f is the much higher strength to weight. As a rough estimate, I can replace a given thickness of wood with about 1/12 the thickness of c/f in strength-critical areas, and make up the thickness requirement with a balsa core (for bending stiffness). The net result should be some weight savings. Kevlar is handy for areas requiring toughness or burst-resistance as well, so a c/f shell over a balsa kelvar core is a good combo.

>The main thing to consider is attachment strength. Although the fiber in the resin will offer some holding power you will probably want to find a wood with better holding properties.  I use basswood in my trees as it is light and readily available here but I add strength to it by covering all the parts with epoxy resin. I laminate everything for added strength too.  What I have found is tree makers generally will tell you the best wood  is what they can get in their area at a reasonable price. I laminate everything for added strength too.

I see what you mean, and would use wooden backing plates where any fasteners are anticipated. I figure it makes sense to make the fork and horn out of wood entirely, since there's little benefit there to composites. Then it's just a matter of carefully thinking about the junction between the bar/fork bar/seat.

>Here again your choices are going to depend on what your specific needs are. If I was building a ranch roping saddle and I knew I was going to be roping great big huge steers on a regular basis I might choose different materials. However, if you're going to use resins and carbon fiber, the only real value the material is going have will be its ability to create the shape and anchor attachments.

My non-existent ranch roping skills mean that possibility is a ways off, but it's a direction I'd like to head in. I'd like something that I can drag logs around with for now, and the barrel-like nature of my horse means that the the lower I can keep the horn, the safer things will be. Even the log drags are a ways off, mind you.

>There always seems to be a constant flow of new measuring devices.

This is the only one I've found helpful lately. Bit easier then the rulers on their own.

AdamTill
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 Posted: Mon Feb 8th, 2010 04:03 am
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This weekend I got to the point where testing an initial shape seemed like it would be useful, so I knocked together a mockup tree out of 1/4" cardboard. Using a cinch I had on hand, this was what it looked like:





The placement came out pretty decently, I think. The blue chalk lines were done to see whether the saddle moved when Tindur did.

On the plus side, when I placed pressure over where the saddle seat would be, there was no additional pressure under the bar tip that overlaid the shoulder. There wasn't as much clearance at the shoulder as I had intended (ie any), but the bar was just touching the hair (change #1 is to add a finger's worth of clearance there.



Showing the need for more flare at the shoulder, here is a shot with his head bent around to the inside:



The only part of the shape which seemed wonky was a bit on the inside of the bar, between stations 2 & 3. Needed to have the angle flattened out a bit since there was contact on the outside of the bar, but not on the inside. There was clearance between the red marks on these bars:



There also wasn't quite as much clearance under the rear tip of the bars, so I cranked those up by another 1/4" or so.

Since there were a number of folks working in the arena tonight, I decided to just walk Tindur out in the barn isle. I tried raising and lowering his head, turning in tight circles, and doing as much as we could within the confines of the isle.

Even with very loose "girth straps", the tree didn't move a whole bunch. Since the bar tips contacted his shoulders in tight turns, it got a bit cockeyed after a while. Still, it only slipped back about 1" or so, so I think that's okay for a first approximation.





I've already made the design changes to the model, and I plan to try again tomorrow. Should hopefully be able to do a bit more with a quieter arena as well.

AdamTill
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 Posted: Tue Feb 9th, 2010 04:28 pm
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Tested out the new shape, and it now works quite well.

With Tindur's head up as far as he could reach it or around to the side touching the girth, the front bar tips just skim the hair at his shoulders.

I think I have a bit too much rock at the rear bar tip now, since while I can fit a finger underneath it at rest, even with his back dropped as far as he could, there's still a bit of clearance under there. I think I can usefully reduce that, and gain a bit more support area through the majority of the fitting range.

Even better, the tree seems to stay in place very well while he's moving. I had the arena to myself last night, so we went in and did a full in-hand session to see how things would move about. We did a half hour of shoulder-in, sidepassing, turns on the forehand and hind, and walk/gait/trot transitions, and it didn't budge a mm.

Near the very end when we were playing with walk/halt/trot transitions and Tindur was rocking back and energetically leaping into the trot from a standstill, I got the tree to slip back by about 0.5" after a set of three of these. I can live with that, since the coefficient of friction between paper and slick hair is much lower then the final saddle fleece on blanket should be.

So, I think I'm pretty close to a finished shape, unless anyone can see anything I'm particularly missing. All that's left is to make the adjustment to the rear rock, re-establish a level line on the saddle shape, and then replot the curves to account for the thickness of compressed fleece and a thin navajo blanket.

Next step would be to plot out some crown (?) profiles for the lower bar profiles.

Photos:

Clearance at bar tip



Nice fit in middle



Clearance at back of bar



Shoulder with head dropped



Took some rather unexciting video as well, and things seem to stay is place well. The bars seem to move with his back well side to side, and don't overshoot or undershoot the movement.


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