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I found this online and thought it might be of interest:


STANDARD & METRIC THREAD SIZES

STANDARD thread size refers to a thread measurement system commonly used in the United States called the 'Unified Thread Standard'. This system uses two numbers to identify thread size, for example: 1/4-20 or 2-56.

The first number references to the major diameter of the screw (major diameter is the outside diameter of the screw measuring on the outside of the threads, minor diameter is the smaller shank diameter, measuring between the threads). Larger screw sizes typically use a fraction in inches to identify major diameter, so a 1/4-20 screw has a major diameter of 1/4". Smaller screw sizes will use a 'gauge' number such as 0, 1, 2, 3, 4, 6, 8, 10, etc., to identify major diameter.

The following formulas can be used to translate the gauge number into decimal inches or metric (or use cross refernece chart below).
Where 'n' equals gauge number:
n x 0.013 + 0.06 = major diameter in decimal inches
n x 0.3302 + 1.524 = major diameter in millimeters

The second number (80, 72, 64, 56, 32, 20, etc.) specifies the number of threads over a distance of 1" (25.4mm).

So using the above information, a standard thread size of 2-56 has a major diameter of:
0.086" (2 x 0.013 + 0.060)
2.184mm (2 x 0.3302 + 1.524)
with 56 threads per 1" (25.4mm).

Following is a cross reference showing: number gauge / decimal / metric:
       
0   0.060"   1.524mm
1
0.073"
1.854mm
2
0.086"
2.180mm
3
0.099"
2.515mm
4
0.112"
2.845mm
5
0.125"
3.175mm
6
0.138"
3.505mm
8
0.164"
4.166mm
METRIC thread sizes also use two numbers to identify thread size, for example: M3.5 x 0.60. The first number describes the major diameter in millimeters (to find decimal equivalent, divide millimeters by 25.4, 3.5 ÷ 25.4 = 0.137"). The second number designates the pitch of the thread, which is basically the distance from any one point on a thread to a corresponding point on the next thread. Following is a cross reference chart showing how pitch relates to threads per inch (25.4mm):
   0.30mm   84 3/4       0.60mm   42 1/4
   0.35mm   72 1/2       0.70mm   36 1/4
   0.40mm   63 1/2       0.75mm   33 3/4
   0.45mm   56 1/2       0.80mm   31 3/4
   0.50mm   50 3/4           

Mark, I had an encounter with one of those "bashing and smashing machines".  I was on a telephone repair ticket at a local factory.  The factory had previously been used to manufacture cranes.  The new tenant was a hammer shop (drop forging).  I watched with fascination as a large piece of steel about a foot square and several foot long, glowing orange hot, was being hammered......directly below our telephone cable.  Obviously the basher trumped the melted cable!

(We rerouted the cable.)

Ken

No need, Herman.  I trust the forum moderator, and I had planned to text to be from the forum (anonymous).

Ken

"I think I might know the answer.  If customers pay for this jig, they will be disappointed to see it get damaged.  And it will get damaged.  The metal is so close to the grindstone that it's inevitable that it will make contact.  Of course, the damage is inconsequential, it won't hurt the jig."

Herman, one thing I learned while experimenting with the SVD-110 is how easily the extruded aluminum can be filed with a hand file or worked with a belt grinder.  I see your point with many users, however, we need to drop the reverent attitude toward the Tormek and look at it as a very useful tool.

Ken

Mark, this you tube may interest you.  I have found better sources for Larry Williams' sharpening technique.  (I will look more when time permits.)  Larry Williams is certainly as expert as they get.  He presents a different option than is common today.

Ken

Outstanding, Herman!  Good technical video quality and informative.  Your video has all the characteristics of excellent instructional material.

Keep up the good work.

Ken

Jeff,

No further comments seem to be forthcoming.  Would this be a good time to strip away all the comments and post the last version?

Keep in mind that we can alter the text should the need arise.

Ken

ps a monor typo:  I notice in the description of the chisels, an incomplete set of parentheses, before but not after the inch sizes of the chisels.  Would you please correct that.  Thanks.

Fascinating post, Mark.

Herman,

Having the bolt go through a slot instead of a round hole would allow the table to be lengthened or shortened as needed.  (Total length would remain constant.  The only change would be in the projected length toward the wheel.)  Even if the final jig had just a hole (or a couple of holes for some adjustment), having a prototype with a slot would give a good feel for what projected length worked well.

Ken

Tom,

One of the values of a forum like this is having varied backgrounds. As someone who only sharpens my kitchen knives, I'm very glad to have an old knife sharpening hand like you on board.

I hope all the new statistics will also reflect continuing depth and good information as well as quantity.

Ken

Mike,

I have one of the Veritas plough planes (my only L-N or Veritas plane).  What a well designed and manufactured tool!  The "compleat" collector in me made me purchase all the extra blades, inch and metric.  I have had only superb service from Lee Valley (Veritas).

I suspect Lee Valley is much better capitalized than L-N.  I am very glad we have both.

Getting back to honing on the leather wheel:  I think there are two subsets of things which can't be done on a Tormek.  The first is "Tools the tormek Can't Sharpen", tools well beyond the purpose of the tool.  An example of this would be circular or bandsaw blades.  The second (and larger catagory) would be "Tools I Don't have the Skill to Sharpen on the Tormek".  (through no fault of the Tormek)  This group is made up of those tools Jeff can sharpen through years of experience.  I put honing in that group.  I hope to lessen the size of that group.

Ken

Happy Birthday, and many more happy birthdays, Rob.

Ken

Good thought, Herman.  I would suggest making a very simple jig (block of wood with a hole in it).  That would make it easy to drill matching holes in any subsequent platforms which would be interchangeable.

I find this process of adapting and modifying the Tormek fascinating.  Not every path will be successful, but the end results should push back our knowledge frontier.

Ken

Thanks for the kind words, guys.  You two are catching up quite quickly!

For the record, I would rather the forum have twenty more 25 posters than one 500 poster.  I hope the increased activity will also bring us a deeper bench (more contributing blokes for those of you who speak English).

Ken

Rob,

I have found this series interesting:

http://www.youtube.com/watch?v=q7UvwyLSdsM

Just in case the link doesn't work, do a Google on "tubal cain taps".  I think the demonstrator, Tubal Cain, is a retired metal shop teacher.  He has done a series of you tubes. 

Ken