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COG for new TiLIte

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    #16
    Just adjusted the caster angle. I use a process as follows:
    1. Estimate by eye where the fork will be perpendicular to the floor.
    2. I sit in my sofa seat with the chair on it's back, loosen the caster using an allen wrench (see attached picture), adjust the angle, and tighten the allen wrench.
    3. Place the chair right side up on a flat floor and swivel the front end back and forth. Both casters should touch the floor at all times. If not, either your floor isn't perfectly flat or the casters are not aligned.
    4. Swivel the front end back and forth again. Verify that the front end swivels freely. If it's out of alignment, you may feels spots of resistance and/or spots of lifting up or dipping down while turning.


    If the chair passes tests in steps 3 and 4, then the chair is aligned. Otherwise, repeat steps 1 - 4. Each iteration takes about 1 minute.

    There is no tooth and groove. The adjustment is infinitesimal. But no big deal. It's a fast process. Takes me much longer to take the axles out of the casters to remove the dog hair than it does to adjust the angle.

    Putting the chair up on a table to use a square may be more precise. But, I could go through several iterations of trial and error to get the same result much faster with less resources, effort, and frustration.
    Attached Files
    Last edited by August West; 12 Jan 2020, 3:57 PM.

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      #17
      nice fan
      69yo male T12 complete since 1995
      NW NJ

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        #18
        Was about to crop the fan out of the picture. But couldn't get myself to do it.

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          #19
          I didn't have AC in any house until 1993.
          So I collected antique electric fans. I love that early industrial look they have, and with a good cord and some lubrication, they will run 80 years! It WAS a practical pursuit.
          Now, they're all in the basement...excepting 3 or 4 in the garage.
          I'd love someone to take them and I hear they actually have good value. I guess that shows everything is not yet corrupt in our country!
          69yo male T12 complete since 1995
          NW NJ

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            #20
            Fans are an underestimated asset. They keep you healthy and comfy and pay for themselves. I keep my furnace fan on 24/7. It helps to keep the house less dusty and eliminate pathogens. I believe this is even more important for my dog than me. Because the dog is close to the ground where more pathogens can settle and accumulate. The ceiling fans reduce air conditioning usage and feel great all year. The tabletop fan helps to keep the house cool and fresh while cooking.

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              #21
              Oddity and August - thanks for all the help and advice you have given me. I have been in the new wheelchair for four days now and it is still stiff. One other question I have is that it seems more difficult to turn the chair left and right, but it is not a showstopper. Do you think once I move the COG up a half inch that it will help resolve the turning issue ? In other words if the front caster axle is closer to the rear wheel axle should that make the chair easier to turn ?

              -Ronnie

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                #22
                Yes. Wheelbase is probably the most significant variable in the turning agility equation, assuming everything else is in good working order (bearings, etc.)
                "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

                "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

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                  #23
                  Originally posted by reaton View Post
                  Oddity and August - thanks for all the help and advice you have given me. I have been in the new wheelchair for four days now and it is still stiff. One other question I have is that it seems more difficult to turn the chair left and right, but it is not a showstopper. Do you think once I move the COG up a half inch that it will help resolve the turning issue ? In other words if the front caster axle is closer to the rear wheel axle should that make the chair easier to turn ?

                  -Ronnie
                  While wheelbase will affect turning, there could be other factors. If turning becomes more difficult as you increase the angle of your turn, then one caster may be higher than the other. Two reasons for this are: 1) caster fork angle is not square (see my previous post), and 2) footplate is not square. Casters not being square will also create safety issues like fluttering casters at increased speed (typically going downhill), which could lock up your chair and throw you out.

                  Otherwise, if turning is difficult regardless of the angle of turn, then it's probably just the longer wheelbase.

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                    #24
                    One thing to note about caster angle and flutter...

                    A fork angle that isn't perpendicular to the floor can actually increase the stability at the cost of agility. A caster angle that is off a bit toward the rear when in the trailing position has increased "trail" which is one way to actually decrease fluttering at high speeds. This is one reason the Freewheel has a fork angle parallel to the floor instead of perpendicular. It's much more stable at high speeds. Flutter based on fork angle is more about one being higher than the other than the angle itself. More trail (a larger difference between the axis of the fork and the caster contact patch) is actually better for less flutter if both forks are off to the same degree.

                    edit: all forks have trail built into them for this reason. Adding more isn't needed but doesn't in and of itself cause flutter unless the forks are imbalanced.
                    Last edited by Oddity; 15 Jan 2020, 8:21 PM.
                    "I have great faith in fools; self-confidence my friends call it." - Edgar Allen Poe

                    "If you only know your side of an issue, you know nothing." -John Stuart Mill, On Liberty

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                      #25
                      Originally posted by August West View Post
                      I have increased dump by 1/2" without adjusting caster angle. It's not the ideal 90 angle but I didn't find a difference in turning. But I like to keep it 90 degrees just because. Not sure why you call it a pain. On my TRA, it's just loosening a bolt, adjusting the caster angle, and tightening the bolt.
                      Last TRA I had was when they came out; it was a pain getting the two to line up properly. I hope the last series of TRA's use a different design for adjusting the barrel housing.

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                        #26
                        Originally posted by Patrick Madsen View Post
                        ...it was a pain getting the two to line up properly.
                        Still could be a pain or it could be easy depending on how you measure a successful result - quantitatively or qualitatively. A quantitative measure would be setting each caster angle at 90 degrees with a square. That will require multiple resources, time, and effort. A qualitative measure would be setting each caster angle at 90 degrees by eye and checking for smooth turns. That will require an allen wrench, a flat floor, and a few minutes.

                        I prefer the qualitative approach. Good enough is good enough beyond which point you're just polishing cannon balls - a needless level of refinement.
                        Last edited by August West; 16 Jan 2020, 2:56 AM.

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                          #27
                          lol, yep cannon balls don't need to be shiny.

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                            #28
                            And your caster angle doesn't need to be exact. After all, it will get thrown away from 90 degrees the first time you hit a pothole.

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