Thread: Marking Gauges 101 - questions, parts and other random stuff

Originally Posted by poundy

First item on my shopping/research list is a brass knurled screw. So assuming M6 is the right size, and is available, how long should the thread section be? I'm imagining 15mm is too short, 20mm borderline, and 25mm would be "ideal" ? You'd want sufficient length to go through the insert and timber and make contact with the beam, so it's probably a function of the timber as well, depending on how likely it is to split?

It's better if the screw does not make direct contact with the bar as the screw has too small a cross section and combined with the turning action of a screw will crush the timber of the bar. The screw should contact a pad of brass or similar that has a larger cross section and dos not turn.

This is one way of doing them
details.jpg

Knurled knobs are not essential - this one uses a small cabinet knob.
IMG_5210.jpg

In this picture you can see the pad (P) and a different way of locating the screw with a small brass block (B) or insert through which the screw is threaded.
I made this knob from brass rod and even though it's smooth it works fine.
Ebonysmallparts.jpg

and in your example, how long is the bolt section?

Originally Posted by poundy

and in your example, how long is the bolt section?

I'm guessing they are ~25mm but I will measure them and get back to you.

30mm.

Originally Posted by poundy

... assuming M6 is the right size, and is available, how long should the thread section be? I'm imagining 15mm is too short, 20mm borderline, and 25mm would be "ideal" ? You'd want sufficient length to go through the insert and timber and make contact with the beam, so it's probably a function of the timber as well, depending on how likely it is to split? ......

The length of thread required for the thumbscrew obviously depends on the size of the stock, & where you position the screw. For 'regular' gauges, I make stocks approximately 65mm wide and about 55mm deep. I put the screw on top, which doesn't need as much 'reach', & it takes less than 15mm of thread to comfortably do the job. I've made a few with the thumbscrew on the side, & that takes a longer screw, but certainly no more than 25 for that size (BobL's gauge must be a bit bigger than mine). As Bob has shown with his excellent diagram, you can easily compensate for a shorter screw by making the slug on the shoe a bit longer, just make sure you position the nut so the screw can reach a couple of mm past it.

Even if you do have a screw long enough to reach the beam, don't let it meet bare wood. It's fine to use a 1/2" wooden screw against hard woods, but you will mark up the beam in short order with a 6mm metal screw. Even if you didn't mind a scruffy beam, the result of the bumps & dents the screw will make will make it very hard to set your gauge to exactly where you want it. Some sort of metal shoe is definitely required.....

Cheers

So here's an Aussie source for brass thumbscrews. https://www.thewoodworks.com.au/shop...m-pitch-detail

Those screws are nicely made, poundy, my only hesitation is the relatively small head, which looks to be about 12-13mm diameter (estimating by comparing with the known 6mm shaft diameter) & about 6mm long. I put a 16mm diameter by about 8mm long head on my thumbscrews. It's partly for more finger-grip, but also it looks more in proportion than a tiny head. To show what I mean, I dropped a 1/2" diameter screw in the 'standard'-sized gauge in the centre one of these three: Knobs cf.jpg

To me, the 1/2" diameter looks a bit undernourished compared with the 16mm head on the left, while the small gauge on the right looks fine with a 1/2" head. It's just appearance, the 1/2" head will work as well, particularly if you still have young, nimble fingers.....

Cheers,

I agree with Ian about the sizes.
In this fine adjustment gauge I made in 2007 the main thumbscrew head is I think about 16 x 10 mm and uses 1/4" allthread rod silver soldered into the head as the screw.
The fine adjustment head is 12mm diameter x about 14 mm thick.

Adj_Gaugea.jpg

yes, agreed, they did appear small-ish. And as you say, it's probably more about the overall scale WRT the whole unit than anything. So for phase 1 I'm going for the "rugged" or "ragged" look, whatever they end up looking like, so I will probably err on the side of whatever I end up being able to buy easily..... I do love the look of yours, but do suspect that for a start I should make them functional first Especially since I've got a need!

Speaking of "standard" sized, any chance you can give up some dimensions? Having nothing to compare to, I don't know what stock I should be looking at when I go to start the build... Here's my imaginings.... roughly 200-250m long beam, approx. 15mm sq to start with; roughly 20mm thick stock and roughly 70mm x 70mm for the head. Am I in the right ballpark? For my first effort(s) I might just head to bunnies and get some Tas Oak so I don't feel bad about screwing up

speaking of brass

If I'm going to buy some general purpose brass plate for these, what thickness would I be looking at?

Originally Posted by poundy

yes, agreed, they did appear small-ish. And as you say, it's probably more about the overall scale WRT the whole unit than anything. So for phase 1 I'm going for the "rugged" or "ragged" look, whatever they end up looking like,

Speaking of "ragged", check this one out. I call it "whimsy" and was the result of rattling through a box of offcuts and found a piece of wood that said "I want to be a gauge"
Sheoak1.jpg

so I will probably err on the side of whatever I end up being able to buy easily..... I do love the look of yours, but do suspect that for a start I should make them functional first Especially since I've got a need!

Makes sense.

Speaking of "standard" sized, any chance you can give up some dimensions? Having nothing to compare to, I don't know what stock I should be looking at when I go to start the build... Here's my imaginings.... roughly 200-250m long beam, approx. 15mm sq to start with; roughly 20mm thick stock and roughly 70mm x 70mm for the head. Am I in the right ballpark? For my first effort(s) I might just head to bunnies and get some Tas Oak so I don't feel bad about screwing up

Those sizes sound OK. Curiously the gauge I use most often is the one I made in year 9 in 1967 - it's only 150 mm long but I like it because it's lightweight.

Originally Posted by BobL

Curiously the gauge I use most often is the one I made in year 9

Curiously I didn't get to make one, the curriculum must have changed... in those intervening years.

I do like Whimsy. Not a small undertaking though !

Originally Posted by poundy

Curiously I didn't get to make one, the curriculum must have changed... in those intervening years.

We got a choice for our end of year project and as I liked bth wood and metal work I chose one that involved both.

I do like Whimsy. Not a small undertaking though !

Actually it was very easy as I already had the wood threading gear. What is not visible in that previous photo is the blade (A blue steel circle with a sharp edge) and the locking ring (a threaded round nut). The male thread is not that well formed and part of that is because it's Sheoak, the other is I was not that careful about it.
whimsy1.jpg

Originally Posted by poundy

.....Speaking of "standard" sized, any chance you can give up some dimensions? Having nothing to compare to, I don't know what stock I should be looking at when I go to start the build... Here's my imaginings.... roughly 200-250m long beam, approx. 15mm sq to start with; roughly 20mm thick stock and roughly 70mm x 70mm for the head. Am I in the right ballpark? For my first effort(s) I might just head to bunnies and get some Tas Oak so I don't feel bad about screwing up

Umm, I did give the dimensions for my 'standard' gauges, Poundy, but they were probably lost amongst all the other words (I did warn you all!) ..... To save you having to search back, they are: Stock ~55mm high, 65mm wide, ~30mm thick. A thin stock is more likely to wobble badly if you get the mortise a bit oversize, but it's more work making a mortise through thicker stock, so you weigh one against the other.. A beam of around 200mm is plenty adequate for most routine marking jobs in cabinet-sized work. Panel gauges are another animal, with beams of up to 600mm, though usually more in the 450-500mm range. Mine are around 400, partly because that fits in my tool cupboard, & mainly 'cos I've never had a need for anything longer, so far. here's a 'standard' gauge with a 200mm beam beside one of my panel gauges (its mate is a pencil holding version): panel & regular Gs cf.jpg

You need enough face below the beam (i.e. on the pointy side) to engage the edge of the workpiece securely. But it doesn't need to be super deep (a bit extra is advisable for a pencil gauge as you have to grip the pencil above the sharpening bevels, which often means the point sticks out of the beam a fair way), because you roll the gauge to 'trail' the point, so there is plenty of depth against the edge. A common 'mistake' I see is to have the pin sticking out too far - keep it short & you'll usually find it easier to control the gauge.

Sizes are really up to you and what you think would work - after all you are making a custom gauge to get a custom gauge. You should follow your own instincts in the beginning & see what works for you - prototyping is par for the course. And I think your plan to keep it basic for the first couple is wise. Iron out the kinks, then dig out the fancy bits of wood & go for high-style once you think you've got it nailed to your satisfaction.

At the other extreme, I have made a lot of small gauges even smaller than this one: Size 3 small.jpg
I find something like this very handy for small jobs (like marking out the mortise in a marking gauge stock )....

Cheers,