[AT] OT pocket knives

[Dave Rotigel]

I'm with you on this Charlie. I was lost right after Larry said "All kidding aside…." I can't get to Portersville this year, but looking forward to the "live demonstration" when it happens.
	Dave

On Jul 13, 2015, at 10:09 AM, charlie hill wrote:

> Larry,  I understand how you are tracing the irregular area with the 
> secondary knife blade but
> how do you allow the main knife blade to behave as you trace?  Do you keep 
> it perpendicular to
> the straight line?  I don't understand at all.   There are multiple ways it 
> could wander including
> at random if not controlled some way.  What am I missing?
> 
> Charlie
> 
> 
> 
> -----Original Message----- 
> From: rlgoss at twc.com
> Sent: Monday, July 13, 2015 9:40 AM
> To: Antique tractor email discussion group
> Subject: Re: [AT] OT pocket knives
> 
> !!!Dave, All kidding aside, a tape measure is exactly how you get the answer 
> out of measuring an area with a make-shift planimeter. You start tracing an 
> area with the main knife blade resting on a straight line that is drawn 
> outside the area you want to measure.  When you come back to the place on 
> the irregular outline where you started, you measure the perpendicular 
> distance to the straight line. That distance multiplied by the distance 
> between the contact point on one blade and the tip that you use as a tracing 
> pin is a direct read-out of the area. The next time I run into you at a 
> show, I'll give you a live demonstration.  I'm headed to Portersville in a 
> little over two weeks.  Are you going to be there?
> 
> 
> Larry
> ---- Dave Rotigel <rotigel at me.com> wrote:
>> Darn, That's NEAT! I use a tape measure in a similar way!
>> Dave
>> PS, Kidding aside, THAT'S NEAT!
>> 
>> On Jul 12, 2015, at 11:02 AM, rlgoss at twc.com wrote:
>> 
>>> I sold both of the polar planimeters I had in our garage sale yesterday. 
>>> They were perfectly  good instruments, but technology has left them 
>>> behind. That fact plus this thread brought to mind that I have carried a 
>>> two-bladed pen knife for many years specifically because you can use it 
>>> as a planimeter in an emergency by opening the large blade completely 
>>> and opening the smaller blade to approximately 90 degrees before 
>>> starting a tracing. It gives a measure of irregularly-shaped areas that 
>>> is better than estimations and requires minimal instruments.  You do 
>>> have to keep the blades sharp so they don't slide sideways over the map, 
>>> and they need to hinge at opposite ends of the knife.
>>> 
>>> 
>>> Larry
>>> ---- jtchall at nc.rr.com wrote:
>>>> Just an update: I bought my son a single blade Case with a 
>>>> plastic/composite
>>>> handle. The knife has a lockback design. After reading your posts it 
>>>> seems
>>>> quite a few folks are using single blade knives instead of the 2 and 3 
>>>> blade
>>>> knives I carry. I carried him to 3 stores and we tried several. This 
>>>> one is
>>>> fairly easy to open and close, yet the blade is never in a "free" 
>>>> rotating
>>>> state. Some of the easy opening ones seemed to me they could open in 
>>>> your
>>>> pocket. The blade is about 3-3.5 inches long and the knife is big 
>>>> enough to
>>>> get a really good grip on. The handle is also textured. The Kershaw and
>>>> Gerber knives some of you suggested were out of stock actually. Anyway 
>>>> he
>>>> seems pleased and has used it the last couple Saturdays around the 
>>>> farm.
>>>> 
>>>> John Hall
>>>> 
>>>> 
>>>> 
>>>> 
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