Plane sizes

I may be a little thick, but could someone explain how the various sizes (Nos. 5 1/2, 4 1/2 ect.)  for planes have been arrived at?  I'm sure there has been articles describing this but I cannot remember where or when and I know that the "knowlegable" Forum will come up with the answer.  I have tried to equate to sole width, blade width, sole length but without joy, solutions please.

John

No idea Woodie, I am as eager to understand this as you are

 

Ron

 

I believe ( though i could be wrong) that the 1/2 is due to the blade in, for example, a 4 1/2 being 1/2" wider than a number 4.

 

 

Baz

Not sure myself, however I have had a quick look at plane number's 4,4 1/2, 5, 51/2, 6 and 7 plane specifications on axminster's web site.

 

A no 4 and 5 plane have 2" wide blades on them, whereas all of the other planes, 4 1/2, 5 1/2, 6 and 7 all have 2 3/8" wide blades fitted. Also the 5 1/2 plane is an inch longer than a no 5, whilst the 4 1/2 plane is an inch and a half longer than a no 4.

 

Hopefully someone else can enlighten us all.

 

Al 

Also someone else who would like to know ME.

 

Could it have something to do with the weight

 

(If you wait long enough someone may know the answer)

Well i'm not an expert on the reasonings, but the 1-8 numbers are loosely based on lengths, the no1 is 5 1/2in long, then from the no2 at 7in, they go up by 1in in length, so the no3 is 8in, and the no4 is 9in (these are rough sizes, I have a no4 that is slightly longer) The Jack or no5 is 14in, then the no6 comes in at 18in, the no7 is 22in and the no8 is 24in.

I was told by my college tutor that the half sizes are more for bench work and have increased width for this. Their lengths mean that they sit in the space between the single figure planes so the 4 1/2 is 10in while the 5 1/2 is 15in. (personally i prefer both the half sizes over the 4 and 5, although I have both of these as well)

 The 1 and two have narrow blades of block plane widths, but the widths are 2in on the 3 & 4 and also the 5.

The half sizes share a 2 3/8 in blade with the 6 and 7, leaving the no8 at 2 5/8in. 

It doesn't give any real indication as to why the sizes used were reached, but again, the longer planes are more for bench work, so wider to suit, much the same as the half sizes.

In the case of the 1 and 2, having held both, i found them way too small for easy use in the normal manner. The no3 i own is also tricky to hold comfortably! The 3 and 4 are maybe close enough to warrant a preference for a smoother, so the jack is logical to step up for a middle ground plane without too much wieght increase, and in similar fashion, the  7 and 8 are close to warrant a choice of weight/width over minimal length increase much the same as the 3&4. The 6 always seems to be the forgotten plane because of it!

Can't say if this is a right assumption, just a few thoughts of my own based on my teachers and the way they are banded in sizes and widths.

 

cheers,

Andy

Hi All

 

I would seem that I am not as thick as I thought.  Thanks for the replies; Andy, it has made a little clearer although not too logical.

John

Hi All

Our dear esteemed forefathers didn't always see things our way. Its all very simple really.

The smallest is No 1 The next is No2 etc until No 8 becomes the largest that is comfortable to use. Otherwize Andy's explanation is spot on. Firms copy one another and just go with the flow -- no need for an exact size or logical progression Our world is TOO set on logic and precision

Toothy

It's all abit like how long is piece of string? another question. how did they arrive at the grading of sand paper I persume 100 is the number of grits to a square inch, how do different manufactures set the grades? so every make is of the same grade.

 

 George

George

 

I think they use a sieve to pass the grit through.  Therefor an 80, 100, 120 sieve will only allow that size grit through allowing the manufactures of abrasives to standardise the grades.  Hope this helps.

John Woddie

George, the size is the number of holes per linear inch, I know this because I am researching a quiz, so you will keep it too yourself?

 

I have looked at the most common grits to see if there is a pattern, and there is of sorts.

 

40, 60, 80. 100. 120 180 240 320 400

 

Up to 120 it is plus 20 and there on to 400 it is plus 60, beyond that I have not gone.

 

As to why well perhaps someone in the trade can tell us

 

Ron