Thursday, July 12, 2018

Marple Chisels Old vs. New

As usual I awoke early, too early to bang around in the shop. What will usually occupy my early morning time is just putzing around cleaning the shop or sharpening iron. This morning what caught my eye was a set of post WWII Marples London pattern firmer chisels. I picked them up several months ago on a whim, not a clue why because I will usually pass on post war chisels. Let's cut to the chase.

As I was looking them over I was surprised by the weight and feel of the chisels. They felt heavy and unbalanced. I just happen to have a pre-WWII London pattern firmer to do a A&B comparison. The pre-war chisel weighed in at 92g, the post-war 102g. Handle size was also different. Pre-war handle measured just under 25mm, post-war just over 26mm. Anyway small differences but with a big difference in "feel".

A photo of the two:



Click image for larger version.


Pre-War on top. Some of the weight and length difference could be because of the number of sharpening but the post-War handle is much bigger.

I haven't used the post-war chisels yet so no clue as to the quality of the iron. Anyway something to amuse and keep from waking MsBubba too early.

ken

13 comments:

  1. Anonymous6:28 AM

    Had been in Montpellier (France) for a few days.
    Congratulations for the grand peanut.
    Sylvain

    ReplyDelete
    Replies
    1. Sylvain,

      I'm jealous of your Montpellier trip :-). MsBubba and I hope this is the last one but we will see.

      ken

      Delete
  2. Steve D8:36 AM

    Has the pre-war chisel been in cold water?

    ReplyDelete
    Replies
    1. Steve,

      Not a clue but I expect not.

      ken

      Delete
    2. Steve D6:59 PM

      That was a Seinfeld reference about shrinkage.

      Trimming the extra length off the new chisels should get the balance pretty close to the older one.

      Delete
    3. I kinda figured it was a guy thing ;-).

      ken

      Delete
  3. Interesting comparison. It never take much of a difference to affect the feel and balance of a tool in our hands. And if you ever loaded an aircraft you know that weight and C of G changes makes a difference :-)

    Bob, and his amazing flying tools

    ReplyDelete
    Replies
    1. Anonymous11:51 AM

      Question for Ken the pilot:
      Generally only the longitudinal place of the CG is calculated for an aircraft. Did you ever fly a passenger aircraft with no passenger but a full load in the hold? Can you feel a difference in behaviour?
      Sylvain

      Delete
    2. Bob,

      Yep, a couple of inches fore or aft can change a great flying aircraft to a handful or the other way. Chisels and most other tools are the same except it isn't inches but maybe mm's.

      ken

      Delete
  4. Sylvian,

    It depends on the aircraft. Lighter aircraft like a Learjet you can tell when a PAX moves. Heavier aircraft like a Gulfstream or a Boeing not really. Cargo shouldn't move so there should not be a change. The operative factor is where is the C.G. is in a percent of MAC. Forward near MAC the aircraft becomes very "stable" and slow to respond. As the C.G. approaches the aft C.G. limit the aircraft is much more responsive to elevator input and once the C.G. exceeds the aft C.G. limit the aircraft may be un-flyable. The amount of lift needed to fly also changes with C.G. position...forward C.G. requires more lift than aft C.G. all because of the lift vectors of the wing vs. the horizontal stabilizer.

    Damn that was a tasty rabbit...Now what time is it. :-)

    ken

    ReplyDelete
    Replies
    1. Anonymous1:49 AM

      Thank you for taking the time to answer.
      English is not my mother language so my question might not have been clear. I was wandering about a high or low center of gravity (in the longitudinal limits). Thinking about the load e.g. on a B747 cargo. I guess the effect is not limiting as I never heard about it.
      On a ship it is of course very important.
      Sylvain

      Delete
  5. Sylvain,

    It's all about "Moment". Weight X Arm = Moment. Moment is the amount of force applied to the C.G,. Unlike a ship the vertical arm of most airplanes is pretty short. While the company I worked for operated the 747 Space Shuttle Transport and a 747 "Guppy" I do not recall any discussion about vertical arm problems but I'll also bet on those it was a consideration because of the longer vertical arm.

    ken

    ReplyDelete
  6. Anonymous6:56 AM

    Thank you.
    Indeed there are a few special aircraft I didn't thought about.
    Sylvain

    ReplyDelete