Arm Reach

[engineAL]

I came up with a formula today to calculate arm reach over a surface. I have not fully tested it, so if you want, you can measure your layout and post the results. Or, if you have a arm reach formula that works that you want to share, go ahead.

x = height of your benchwork in inches
y = arm reach in inches
z = height of you in inches

y = 16 z / x

So if my height is 70 inches and my benchwork is 40 inches high, my formula would be:

y = 16 * 70 / 40

y = 1120 / 40

y = 28

I can reach 28 inches into my benchwork. I'm sure that this value isn't the absolute maximum that you can reach, it is just a comfortable distance.

For those of you who want to know how I came up with it:

I figured that the higher you get, the farther you can reach. However, the higher your benchwork, the shorter you can reach. Therefore, y varies directly with z and indirectly with x. I then plugged in my benchwork's height, my height, and my arm reach and after a bit of tweaking I found the value of 16.

Any suggestions would be appreciated.

[steinjr]

 Or in other words - you did a test, and found that given your height and the layout height - about 28" felt comfortable to you.

 Which is within the range recommended quite standard - no more than 24" - 30" (unless you have access hatches or some contraption to reach further into the layout - a step stool, a topside creeper or some such thing):

 No need to make a bunch of tests to establish whether an average factor is 14.27 or 16.55 - you still will end up with somewhere between 24" and 30" of reach into a layout at chest level, and a little more into a layout at waist level :-)

 Smile,
 Stein

 

[Phoebe Vet]

According to your formula you can reach in 15 inches even if the bench height is 5 inches above your head.

[tomikawaTT]

Your formula is good - for a person with your physical characteristics.

How about a runway model - with disproportionally long legs.

How about a reciprocating engine mechanic - euphemistically referred to as a `knuckle dragger.'  (Just kidding, folks.)

How about a person who has physical disabilities (not PC, I know - but something I have to live with.)

The best way for a specific individual to find out how wide to make his/her benchwork at a chosen height is still empirical experiment - pile boxes of various heights on a dining table and see how far YOU (not Joe Average) can reach.  I'll bet that four different people of the same height will come up with four different answers.

Chuck (Modeling Central Japan in September, 1964 - on benchwork of varying heights and widths)

[CTValleyRR]

Phoebe Vet

According to your formula you can reach in 15 inches even if the bench height is 5 inches above your head.

Yeah, this sounds like one of those formulas that is true at the center of its range of values, but not at the extremes.  Kind of like the Body Mass Index that the medical community likes to use now.  It works great if you're near average height, but the farther you are from that, the greater the tendency of the calculation to call you "over" or "under" weight (at 6'1", it says 168 is my "ideal" weight; I weighed 180 when I graduated from college and I looked skeletal).

I think we should probably go with Stein's guideline:  24-30" at chest height.

[HHPATH56]

To enable me to reach tracks at a greater distance than 28". I mounted my saw mill complex on a kitchen pull-out drawer. Bob Hahn

[richhotrain]

Cool.

I am 6 feet tall.  If my layout is 12 inches off the floor, I should be able to reach 8 feet in.  LOL

[cuyama]

As noted, the formula is incorrect except within a narrow range of values. Also as noted, it's unnecessary.

Decades of real-world experience suggests that 30" is the longest reach with typical layout and operator heights, often much less over scenery without damage. And less again for higher benchwork or with taller buildings or scenery in front.

A simple mock-up will tell you more about your own situation in15 minutes than will hours of calculation and hypothesizing.

Byron

[CTValleyRR]

If you want to persist in the mathematical formula example, someone who's more mathematically inclined than I am can probably give you some real help, but simple division gives you a linear equation.

You will need exponential and / or logarithmic functions to give you the right limiting factors at the ends of your range of potential solutions.

While there probably is a way to derive an actual formula, I'd rather spend my time playing with trains.

[Seamonster]

I said this in another thread about layout reach but it seems appropriate to repeat it here.  Have someone hold a broomstick parallel to the floor at the height you plan to make your layout and see how far you can reach without leaning on the broomstick.  And don't measure to your fingertips because you can't pick anything up with your fingertips or install track or scenery with your fingertips (unless you have the fingertips of a gekko!).

 

[engineAL]

I guess that it is not all that correct or needed. A 3' toddler can not reach 1' over a 4' table! Besides, as noted, what happens if the person is exceptionally tall or has long arms?

If anyone does want to come up with or has a formula that compensates for things like this, still share it. I like solving problems like these but I mine as well just work on my model railroad.

[Hamltnblue]

Reach isn't just about arm length. Your body adds to it. Do you take into account waist height?

If your waist is 36 inches and the layout is at or below that, you get the full addition of your torso to about 40 degrees or so.  Over your waist it would decrease by some amount.

[CTValleyRR]

The essential number here is 225... which is the approximate cost of a topside creeper.  Then you can reach 40" in without trouble.

[steinjr]

CTValleyRR

The essential number here is 225... which is the approximate cost of a topside creeper.  Then you can reach 40" in without trouble.

 Just curious - I realize that the topside creeper can be folded down and stowed away fairly easily, but how much aisle width do you need to set up and use the topside creeper, and how much head room do you need above the topside creeper while climbing up onto it or down from it?

 Is this something that will work with 24-30" aisles, or do you need 40+" aisles to set up the creeper?

Smile,
Stein

 

[mobilman44]

HI!

Always like to see someone applying math to a non-math problem.  I did for years with my picks in the weekly office football pool, which should have embedded the phrase "on any given Sunday" well into my brain.   It didn't..............

For my room filling layout (around the walls with a "hole" in the center for operators), I knew that I could not easily reach the wall areas, especially in the corners.  However, I keep a 12x12x14 carpet covered wood box that I use as a step which makes access to the wall areas fairly easy.  

However, I still can't easily reach the corners.  My solution - the same I used for 14 years on the current layout's predecessor - was to make sure that there was no turnouts or poor trackage or potential scenic problems in the far areas of the corners.  This certainly worked for me, and I recommend it.

In building the layout, I worked from the outside inward - especially in putting down structures and scenery.  Again, this method worked like a charm for me. 

[CTValleyRR]

steinjr

 

CTValleyRR:

 

The essential number here is 225... which is the approximate cost of a topside creeper.  Then you can reach 40" in without trouble.

 

 

 Just curious - I realize that the topside creeper can be folded down and stowed away fairly easily, but how much aisle width do you need to set up and use the topside creeper, and how much head room do you need above the topside creeper while climbing up onto it or down from it?

 Is this something that will work with 24-30" aisles, or do you need 40+" aisles to set up the creeper?

Smile,
Stein

 

Stein,

Keep in mind that Topside Creeper is a trademarked item name  There are several competing products out there, which, due to our American tendency to refer to items by a popular brand name (facial tissue = Kleenex, etc.), are also referred to a "topside creepers" (often with a slightly variant spelling, like Top Side Creeper).  The one I have is manufactured by Traxion Industries and is foldable

I know you're in Norway and would rather have metric dimensions, so I've given both using 2.54cm per inch.  The stabilizing legs (the long ones that stick out at the bottom) are 56" (142.3 cm) long and are 31" (78.7 cm) wide at the ends (outside dimension).  These fold against the uprights to collapse the unit.  So you need an area roughly those dimensions to unfold the unit.  You could probably shorten this a little because the uprights swing up in an arc, so if you had sufficient vertical clearance, you could conceivably have the legs under your layout unit while you opened it, depending on how much clearance there is under your layout.

Mine resides either under the layout (if I'm lazy) or off in the corner by the furnace when not in use.  I have a wide cockpit (9') in the center, so I've never had any trouble finding the space to set it up, and can easily reach the centers of my 5' wide peninsulas using it.

Edit:  BTW, even though one is sold by Micromark, they were developed for auto repair, and are available more cheaply from companies offering tools and customization parts for cars and trucks.

[steinjr]

CTValleyRR

 

I know you're in Norway and would rather have metric dimensions, so I've given both using 2.54cm per inch.  The stabilizing legs (the long ones that stick out at the bottom) are 56" (142.3 cm) long and are 31" (78.7 cm) wide at the ends (outside dimension).  These fold against the uprights to collapse the unit.  So you need an area roughly those dimensions to unfold the unit.  You could probably shorten this a little because the uprights swing up in an arc, so if you had sufficient vertical clearance, you could conceivably have the legs under your layout unit while you opened it, depending on how much clearance there is under your layout.

 Sounds like at least a 31-32" wide aisle would be a good idea if you want to unfold and fold it, then, and then twisting it around, so it's legs go under the layout.

 Thanks for the answer!

 Smile,
 Stein

 

[CTValleyRR]

steinjr

 

 

 

 Sounds like at least a 31-32" wide aisle would be a good idea if you want to unfold and fold it, then, and then twisting it around, so it's legs go under the layout.

 Thanks for the answer!

 Smile,
 Stein

Actually, the legs would stay on the floor the whole time... the top part is only about 25" (63.5cm) wide, so as long as the aisle was that wide at the layout height, you could pull it upright in that space.  The legs could be under the layout the whole time, thus saving you a couple inches / cm.

[galaxy]

If your formula works for most people, tehn very good.

I just plain old stick with about 16-18 inches, about the length or my arm minus my hand. My hand has to be most likely bent to do something so I can't include it. I just measured my arm and know I can't bend to extend my reach, so I go by that rather than some formula.

I built my layout at a comfy height so I don't have to bend over it to work/play on it without straining my very bad back.

SInce it basically a level amost-plywood-prairie, I find it works well for me.

 

[jwmurrayjr]

 A few small pop-ups can make life much easier and fun... If you can't avoid the deep bench work...and sometimes you need it.

 

All foam.

 

[ef3 yellowjacket]

In a conversation with veteran modeller Harold Horner once upon a time, he came up with this advice for me: 

No deeper than you can comfortably reach.  I think harold had a very valid point.  I am "blessed" with gorilla-like arms and do have a pretty good reach-BUT:  I have a bad rotator cuff, arthritis, etc, so I will keep the maintainence end of it as accessable as I can.

EF-3 Yellowjacket

[R. T. POTEET]

Phoebe Vet

According to your formula you can reach in 15 inches even if the bench height is 5 inches above your head.

I laughed for 10 minutes over this!