Locating bolt holes in replacement saw handles

[Isaac Smith]

I finished shaping a replacement handle for an old Disston saw today, only to face the challenge of locating the holes for the saw bolts.

Given the moderate rarity of this saw, enlarging the existing holes in the blade was not an option, so I needed to align the holes in the new handle with them very closely.

I came up with the solution below. While it undoubtedly has been used by others, I have not yet seen described. Its chief advantage lies in being able to mark the holes while the handle is positioned on the blade. All that is required is a flat surface, a piece of tape, a square. And a pencil, which, despite a fascinating collection of mechanical pencils and leadholders, is invariably the single most difficult item to find in my shop.


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Mark the heel of the blade on the tape, then align the square with the horizontal center of the hole. Mark this location on the tape, then read the vertical location of the center of the hole and write that on the tape.



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Showing the marks and measurements for the centers of the holes.



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With the handle on the blade, transfer the measurements to the handle. Make sure that the heel of the blade is positioned on its mark, or all of the holes will be off.



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It doesn't get much better (or easier) than this.

[Matthew N. Masail]

Well Done! ! thanks for the tip

[Mike Hutchison]

Nice Work Isaac:
In the surveying world that is tangent and offset location;
maybe I should have used that method on the monster
Disston I made a new handle for but haven't gotten around to
finishing.
Mike H.

[Chris Griggs]

My lord! Why didn't think if this (slapping self in forehead). This is hands down the hardest part about making a replacment handle. In the past, I always marked holes by holding the plate/spine up to the handle roughly in to where I thought it would seat in the mortise/slot (which isn't that accurate), then left a little room for adjustment in the mortise for the spine, and than slowly dialed it in to fit the hole alignment. It's a troublesome process and this is sooooooo much easier and more accurate looking.

THANKS ISAAC!

[Judson Green]

Looks like ya got a handle on it. (cue rimshot)

But seriously that's pretty clever well done sir

[Lonnie Gallaher]

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Showing the marks and measurements for the centers of the holes.





Isaac, great use of the xy coordinate system. It is a very accurate way of locating a point. I don't know if others picked up on your first dimension from the plate heel or not, and possibly everyone else already knows what was represented here, but I thought I would comment on the use of the (+) sign after a dimension. This is a way of indicating that the dimension given is not exact and in this example the dimension of 1 13/32 + indicates that the exact dimension is 1 13/32 plus 1/64 or half of the distance between the finest markings on the rule. In this example the exact dimension is actually 1 27/64. Quite an awkward number, but 1 13/32 + is very easy to find.

Great use of shop layout practices. Of course Isaac could have another use of the (+) sign, but that is my experience from working many years in the steel fabrication industry.

[Hilton Ralphs]

the dimension of 1 13/32 + indicates that the exact dimension is 1 13/32 plus 1/64 or half of the distance between the finest markings on the rule. In this example the exact dimension is actually 1 27/64.

Thanks Lonnie for this information, I learnt something new this evening.

[Jim Koepke]

Great idea, thanks for sharing.

My suggestion would be to submit this to one of the magazines as a shop tip.

jtk

[Winton Applegate]

Issac,

Excellent !
Well done.
That works and that is the main thing.

Lonnie,
(or anyone else with thoughts on the following)

Not to be critical but simply to add another dimension (so to speak) to the discussion. When talking two dimensions would it be correct to say "X , Z coordinate system" if one of the dimensions is vertical ?

Being not of a traditional edumication (read self taught) and always working with the XYZ for machine tools, robotics etc., the vertical, in my world is the "Z" axis.

Sheet metal and my hobby interests

Using quasi sheet metal layout info I read about I pulled dimensions from scaled planes I had drawn, then converted dimensions to 1 to 1 and transferred these and laid out on a flat paper a template that when cut out and wrapped around a structural tube the exact shape for one tube to "fish mouth" to another tube was created. Then I scribed a line to cut out the very complex shape. I just machine it that way now with no template but that first success with the basic system you are describing, before I had machine tools, was an enlightening moment for me. Very satisfying.

Issac,

Thanks to your post I have yet another use for that system.
Thank You !

[Isaac Smith]

...in this example the dimension of 1 13/32 + indicates that the exact dimension is 1 13/32 plus 1/64 or half of the distance between the finest markings on the rule. In this example the exact dimension is actually 1 27/64. Quite an awkward number, but 1 13/32 + is very easy to find.

Great use of shop layout practices. Of course Isaac could have another use of the (+) sign, but that is my experience from working many years in the steel fabrication industry.

That pretty much covers it. I find the 64th's scale to be a little fussy and slow to read, so unless I really need it I usually use the 32nd's.

I picked it up doing trim work, where the finest gradation available on a tape measure was 16th's. "+" meant about a 32nd extra. For even smaller adjustments, there were several descriptive and colorful epithets whose sharing would no doubt lead to my banning here.

[Jessica Pierce-LaRose]

Awesome. Thanks for sharing. A head-slapping why didn't I think of that moment, for sure.

I'd have been tempted to do basically what you did, but with ticked sticks or pen marks on a taped square blade or something, but just because I'm terrible at numbers.

[Lonnie Gallaher]

Winton,

Thanks for the clarification. You are right. In an elevation view, the side of the saw plate is in elevation, the Z axis is veritical and the X axis is horizontal. The X Y as used in numerically controlled and in 3D modeling is represented in the plan view. That is looking straight down at the object. I was using the xy more in the mathematical grid format where x is horizontal and y is vertical. The offset x and y would produce the location.

Thanks for the imput, Z is vertical in my world as well. I do 3D modeling.