Centre Marking Gauge

[Mr Ed]

Saw this on Tom Eastons blog today. Maybe not new to you wise men on here, but it was new to me and something I intend to copy.

What a simple idea, intended for resawing mainly.

Cheers, Ed

 

[Mattty]

That is clever. First time i've seen that jig. Cheers :ho2

 

[wizer]

I wonder how long the blade is and what it's made from? Nail?

 

[Ironballs]

It does look like a nail, I imagine you could sink in a circular blade on an axle that could also rotate by 360 degrees, thereby allowing a finer line to be cut but still in the centre

 

[Mr Ed]

It is a nail.

Here's alink to the blog if you're interested.

http://www.bob-easton.com/blog/?p=346

Cheers, Ed

 

[wizer]

yes I think for general woodworking purposes it would need to be thinner/pointier

 

[dennyom]

I made one a few days ago to center mark some poplar for resawing. I used a 3/4" square piece of oak a few inches long and two 8p nails for guide pins. For the marking pin I used the point of an inexpensive compass. The nails were cut so that they would only extend about 1/2 an inch out of the wood. The cut off nail ends were rounded to avoid marring the work piece. The holes for the nails and point were drilled a bit undersize for a good tight fit. I pressed the point in so it just barely poked through the wood. It took all of about 10 minutes to do. I did not shape the wood body at all but might make another that is a bit prettier. One problem is that it only marks up to about 1/2" or so from the end of the board. Other than that it worked great and left just a faint centered scratch.

 

[bugbear]

Saw this on Tom Eastons blog today. Maybe not new to you wise men on here, but it was new to me and something I intend to copy.

What a simple idea, intended for resawing mainly.

Cheers, Ed

A very slightly more complex example of this principle, but more usefu, since it solves a more difficult problem, is the aeons proved "spar gauge"

http://www.amateurboatbuilding.com/arti ... spars.html

BugBear

 

[Harbo]

I use a pencil, guided by my fingers and centered from both sides - very quick, easy and accurate enough

Rod

 

[Racers]

Hi,

I do the pencil and finger trick my self, its good to see just how close you get to the middle first time.

Pete

 

[TheTiddles]

The problem is that it doesn't work on short stock and it can't scribe right up to the end of the piece, there is a much better way but I can't reveal it just yet...

Aidan

 

[bugbear]

Both the centre gauge and spar gauge have a property which none of the alternative (to my knowledge) have. They operate nicely on tapering workpieces. They simply centre continuously as they go...

BugBear

 

[dunbarhamlin]

Sorry BB, though I often see this touted it just isn't true. They don't work with tapered stock - when I find where I've put my phone I'll put up a pic.

Here we go:

Not a very good pic, but the scribe lines from holding the gauge with first the nearside fence trailing, and then the farside clearly show the point.

Cheers
Steve

 

[bugbear]

Sorry BB, though I often see this touted it just isn't true. They don't work with tapered stock - when I find where I've put my phone I'll put up a pic.

Agreed - for steeply tapered stock it doesn't hold true; the error is pretty much proportional to the degree of taper.

However, for spars and masts (see picture earlier) the taper is such that the tool works well.

BugBear

 

[woodbloke]

when I find where I've put my phone I'll put up a pic.

Steve

Hi Steve - own up...you still haven't been to SS have you? :lol: :lol: - Rob :ho2

 

[Green]

I thought these tools were common. I used them all the time as a coachbuilder.

 

[bugbear]

I thought these tools were common. I used them all the time as a coachbuilder.

You were a coachbuilder?!? I thought that trade died out in the 30's !

Coachbuilders (according to old catalogues and/or Salamans dictionary) used all manner of "interesting" tools.

BugBear

 

[Green]

I was but the company folded a year after my apprenticeship ended (victim of the 90's recession?) and there was no-where else within sensible travelling distance to carry on working in the trade.

We used to make and fit out all manner of one-off vehicles from the chassis up. Was a very interesting job.

 

[dunbarhamlin]

Agreed - for steeply tapered stock it doesn't hold true; the error is pretty much proportional to the degree of taper.

Yes, that's why I used an extreme taper to make it obvious.

For setting out masts, it would just make the guide lines lazilly hellical and a bit shy at the thin end. Since the error increases the greater the difference between pin separation and stock width, wonder if they use several over a long length?

Where accuracy is required, there is an alternative using two circular discs, each with two pins at opposite ends of a diameter, slotted along a radius at a common angle to said diameter with a scribe in intersection between the two discs slots.
Again, this is limited to symmetrical tapers, though they needn't be linear.

 

[bugbear]

Where accuracy is required, there is an alternative using two circular discs, each with two pins at opposite ends of a diameter, slotted along a radius at a common angle to said diameter with a scribe in intersection between the two discs slots.
Again, this is limited to symmetrical tapers, though they needn't be linear.

You're gonna have do me a diagram or photo of that - my visualisation is failing me :-(

BugBear