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Occupied Frame Length? What is it?

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  • Occupied Frame Length? What is it?

    I have seen the word "Occupied Frame Length" several times already and yesterday it popped up in another equipment thread.

    I know how to measure it but what does it mean? What is the purpose of it?

    I goggled it and very little information came up. Mostly what two points to measure at.

    So, what is Occupied Frame Length and why is it important in fitting a new 'chair?

    Can someone educate me on it?

    "We must overcome difficulties rather than being overcome by difficulties."

  • #2
    Because it's the measure from the front of your back posts to the front of your foot rest, it's a measure of how compactly you are sitting. If you are sitting too compactly (feet behind the knees), you may be forward tippy. Hence, you want a minimum user occupied frame length for stability. Of course, the actual value varies from person to person and chair to chair.


    • #3
      It is important for folks who want to accurately define where their feet will contact the footrest, and also the angles the ankle and knees will have while seated. It's also useful when going from one brand of chair to another. They're not all measured exactly the same, seat depth wise and where the bend starts for the front angle, so OFL allows a standard of measure that any fabricator can use to determine where to start the bend and what angle to use. Most people try to approach foot placement using seat depth, front angle, and length after seat pan before the bend starts. OFL is a more direct measure; it addresses the end goal directly (desired foot placement) and can help inform the other choices; as opposed to those other (less clinically relevant I.e. front angle) measurements dictating foot placement.

      Edit: It was brought to my attention by member SCI_OTR.
      Last edited by Oddity; 09-01-2018, 04:59 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


      • #4
        Can someone provide the info how to figure out the OFL? I searched OFL and can’t seem to find the skeptic threaaboht how to calculate/measure it. currently specking out new chair and I feel very cramped length wise so I think my OFL is off and I am sitting too compact.


        • #5
          SCI-OTR explains it all.


          • #6
            Originally posted by titanium4motion View Post
            So, what is Occupied Frame Length and why is it important in fitting a new 'chair?
            We’re in the process of ordering a new chair for my son. He’s had an Icon for 6 years, and it’s been adjusted many times as he’s grown from age 9 to 15. We’ve had a physio and the chair distributor measure him up for the new chair, which involved all the normal seat measurements. Some of the other measurements for this particular chair are fixed.

            There is an option of a 90 degree front end angle, which my son liked the look of due to its compactness, so we were almost at the point of selecting that option, so the plan was that I was going to the distributor’s shop to finalise the last few items. Just before I went, I remembered about OFL, and measured it on the Icon. When I was at the shop, I mentioned OFL (which the distributor hadn’t heard of before), but he went hunting for that measurement online. It wasn’t there, but we were able to work out that the 90 degree option reduced the OFL by 95mm (ie not insignificant). He then measured the OFL on the standard chair front end that he had in the shop, which showed that the OFL was 60mm less than my son’s current OFL.

            So, had we pulled the trigger on the 90 degree option, the OFL would be 155mm (about 6 inches) less than the Icon configuration that my son is currently very comfortable with. We all agreed that was a huge difference, so have gone back to the standard configuration, on the basis that a 60mm difference is manageable.

            The distributor learnt something (and, having dealt with him before, he’s the type of person that will take this information on board and actually use it!), and I was relieved that we didn’t make a big mistake! I’ve never seen OFL mentioned anywhere else but CareCure, and am thankful that SCI_OTR came up with it some years ago (as Oddity mentioned).
            Last edited by Gordy1; 09-01-2018, 07:36 PM.
            Gordon, father of son who became t6 paraplegic at the age of 4 in 2007 as a result of surgery to remove a spinal tumour.


            • #7
              I have to give credit to Paul Schulte from Top End who originally told me about that measurement at ISS back in 2011. We were discussing how one could accurately spec a fully welded 7000 series aluminum box frame model they were developing using an existing chair.

              The ability to verify that the specs I obtain for a veteran's new chair will result in the dimensions we want has been invaluable.

              While I may have led the charge to include OFL on every TiLite CAD, it only happened because everyone here adopted it.