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6000 series aluminum vs 7000 series

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    6000 series aluminum vs 7000 series

    Hi Everyone,

    Still doing wheelchair research and would appreciate some input re: 6000 and 7000 series aluminum used in frame construction. I’m looking at the newly launched Top End Crossfire T7A (7000 series aluminum) and the TiLite Aero Z Series 2 (which I believe to be, but am not certain, is made from 6000 series aluminum).

    From what I understand so far, 7000 is lighter and stronger than 6000 as a result of its manufacture (heating) process and there are differences in corrosion susceptibility (e.g. pitting. I live in a 4-season climate which means sleet, snow and sidewalk / road de-icers in winter. Not sure how these chemicals effect either 6000 or 7000.). 7000 also seems a bit more pricey. Just wondering if there are significant differences in the two materials re: responsiveness, efficiency and durability (e.g., work fatigue, corrosion). Or, are the differences really more a matter of preference and perception?

    I’m an active user and a left-side hemiplegic so I can’t do wheelies or bump down stairs (don’t have enough control of the chair to do this – unless someone out there knows something I don’t and is willing to share . . . ). So my chair doesn’t get that kind of stress, but I do bump into things and have had to use the front of the frame to help open heavy doors. I use my less affected right arm and leg to self-propel and I find big (wide, long), “bulky”, heavy chairs hard to manage (maneuverability). I also have to correct for the chair’s drift to the left as a result of my arm push – have to correct this with my leg pulling the chair forward (gives me killer ham cramps) while flicking/turning my foot to the left/”inside” so the chair moves back to the right and I can stay on a (semi-) straight line. Inefficient and tiring, but don’t know of another way and really, really don’t want to go the electric/power route yet. (I know of one arm drive chairs (TiLite makes one!) but they add so much weight and it doesn’t appear E-Motion wheels can be effectively pushed by a one-arm user).

    Thanks for your input!
    Do not confuse silence with consent or fatigue for indifference.

    #2
    This is the little I know and believe:

    "TiLite uses 6061-T6 aluminum alloy that combines aluminum with magnesium and silicon. 6061 aluminum is commonly used in heavy duty structures requiring good corrosion resistance and in high pressure applications."

    The premier of Sunrise Q7 was the first time I heard of series 7000 aluminum. The Q7 premiered last fall while I was shopping for my first chair. I seriously considered it, but ruled it out because the available rsh wasn't low enough (I can stand, and often do, so I like my chair close to the ground).

    I ended up choosing the TiLite AeroZs1 (series 2 wasn't available yet). I already had shoulder issues as an AB, so i ordered the Z with reinforced frame for future rerofitting of power assist. At the time of my order, the Q7 was also available with power assist. After I ordered the Z, I read here on CC that Q7's fitted with power assist were cracking. Soon thereafter I noticed this note appearing on the Q7 order form:


    In my opinion 7000 is currently a poor attempt to compete with the titanium market. 7000 technology may improve with time, but if weight were an issue, and I was buying today, I would choose titanium over 7000 hands down. . . just my opinion.
    Last edited by chasmengr; 13 Apr 2011, 7:52 PM.
    Chas
    TiLite TR3
    Dual-Axle TR3 with RioMobility DragonFly
    I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

    "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
    <
    UNKNOWN AUTHOR>

    Comment


      #3
      Originally posted by Jonna View Post
      I’m an active user and a left-side hemiplegic so I can’t do wheelies or bump down stairs (don’t have enough control of the chair to do this – unless someone out there knows something I don’t and is willing to share . . . ).
      I can't remember the correct term, but some manufacturers offer an option that ties the two rear wheels together so a single-armed person can propel a chair. I think it's aimed at amputees, but you may like it. I came across it while researching for my chair choice, but sadly I don't remember where it was or what it's called.
      Chas
      TiLite TR3
      Dual-Axle TR3 with RioMobility DragonFly
      I am a person with mild/moderate hexaparesis (impaired movement in 4 limbs, head, & torso) caused by RRMS w/TM C7&T7 incomplete.

      "I know you think you understand what you thought I said, but what I don't think you realize is that what you heard is not what I meant."
      <
      UNKNOWN AUTHOR>

      Comment


        #4
        Ah, good to know, and thanks for posting the info about the Q7 cracking problem. I'm paying out of my own pocket, so if I invest in titanium I'll have to go cheaper on the backrest and cushion. I consistently read good things about TiLite and the Aero Z here on CC and with your helpful info (6000 Al seems okey-dokey, tried and tested in the real world vs the newbie but much touted 7000) I'm leaning that way so can spend a little more on the backrest and cushion. Thanks, chasmengr. (Yeah, I think the option that ties the two rear wheels together is the One Arm Drive that adds so much weight which I'm trying to avoid.)
        Last edited by Jonna; 13 Apr 2011, 8:20 PM. Reason: clicked "enter" before completing message
        Do not confuse silence with consent or fatigue for indifference.

        Comment


          #5
          I had a buddy that was a hemiplegic so I drilled a hole in the fork, stuck a bolt in so he could rest his foot on it and steer with that foot.

          Comment


            #6
            I like it! Sounds like a marketable idea to me . . .
            Do not confuse silence with consent or fatigue for indifference.

            Comment


              #7
              7000 aluminum

              in case anyone wonders back to this thread. most of the 7000 series aluminum being used today are NOT considered weldable. there are two series aluminum that are weldable 7003 and 7005. welding all other 7000 series creates a weakness for cracking.. here's a great article about welding, heat treating, stamping different aluminum series.

              http://archive.metalformingmagazine....00/06/Alum.pdf

              Comment


                #8
                When it comes to the Q7 they don't weld the 7000 series aluminum. The way they do it is shape the aluminum and do all the welds, THEN heat treat it to turn it into 7000 aluminum.

                From my research, for someone who can afford it titanium is a better choice. For those who cannot (such as myself) 7000 aluminum is a great way to get a lighter weight aluminum chair.
                Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

                I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

                Comment


                  #9
                  Here is another summary of various Al alloys. Note that the 6061 must also be heat treated after welding. http://www.aircraftspruce.com/catalo...s/aluminfo.php

                  Wikipedia also has lots of interesting information.
                  T4 complete, 150 ft fall, 1966. Completely fused hips, partially fused knees and spine, heterotopic ossification. Unsuccessful DREZ surgery about 1990. Successful bladder augmentation using small intestine about 1992. Normal SCI IC UTI problems culminating in a hospital stay in 2001. No antibiotics or doctor visits for UTI since 2001: d-mannose. Your mileage may vary.

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                    #10
                    To hell with titanium. Ditto for 7000.

                    Spend money but spend it on good parts like the wheels, back and cushion.

                    The only one who notices the difference between 6000 and 7000 is the bottom line of the manufacturer.

                    6000 will survive a lot of a harsh conditions. Buy touch up paint when you need it. You can get stuffed anywhere.
                    Last edited by radio_buddha; 5 Dec 2011, 9:02 PM.

                    Comment


                      #11
                      Aluminum is aluminum, at least in terms of weight. Regardless of 'series' a block the same volume of two different types will weigh essentially the same. Just as with titanium, the difference that matters is whether or not the design of the parts is done in such a way as to leverage the particular properties of the different aluminum alloys.
                      "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

                      Comment


                        #12
                        the volume is different, that's why 7000 chairs weigh less. Due to the increase in strength, they use much thinner aluminum for the same end strength. Resulting in a lighter chair. This is why titanium chairs are lighter than aluminum. The strength of the metal is much higher allowing them to use much thinner metal for the same end result.
                        Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

                        I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

                        Comment


                          #13
                          Thinning the walls is one way to take advantage of a stronger alloy to save weight. There are other engineering techniques as well, like buttressing and ovalized tubing in key spots. The same tubes of one series or another will weigh the same. The reason I think this is important to understand, IMO, because a company willing to bend the same chair out of whatever metal you want, or that simply updates their material without also re-engineering the inside of the tubing is essentially selling 'metal hype'. Before you decide on one material or another it might pay to understand why it was chosen by the manufacturer. Whether or not it was to actually make the chair BETTER, or just to jump on the 'alloy hype' train to help sell more chairs.
                          "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

                          Comment


                            #14
                            The fact that 7000 series aluminum cannot be weld would be a concern to me. If down the road sometime your frame broke but could be fixed with a quick weld, you'd be out of luck with 7000.
                            C5-6 Complete - 8/13/1982

                            Comment


                              #15
                              The Q7 uses oval tubing as well to add greater strength over the typical round tubing.
                              Board Member of Assistance Dog Advocacy Project working in Education. Feel free to ask me any service dog questions!

                              I am not paralyzed. I have a genetic connective tissue disorder with neuro complications and a movement disorder.

                              Comment

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