Wedge angle?

[Chris Knight]

I want to make a traditional panel gauge in wood with a trapped wedge for securing the stem. Can anyone tell me what angle I should cut the wedge at for the best trade-off between a secure fixing and ease of use. (I don't want it to come loose accidentally, neither do I want to have to hammer it loose!)

 

[Wiley Horne]

Hi Chris,

Maybe the best wedge action I have experienced is on a wedge-arm sash fillister, made by D. Malloch & Son, Perth.

Here is a link to a direct scanned image of a wedge from that plane.

http://www.traditionaltools.us/cms/modu ... 7-sash.jpg

You can see out at the business end of this wedge, that there is a slight crushing where it engages.


Wiley

 

[JesseM]

I want to make a traditional panel gauge in wood with a trapped wedge for securing the stem. Can anyone tell me what angle I should cut the wedge at for the best trade-off between a secure fixing and ease of use. (I don't want it to come loose accidentally, neither do I want to have to hammer it loose!)

I made one myself recently in cherry which turned out very nice. I'll try and post a pic of it tonight. I think I heard 10 degrees was optimum, but I just made mine by ear. There is a bit of a design flaw with mine which I hadn't foreseen. I decided to use a dowel for the stem, mainly for the ease of cutting the tenon and availability of already sized stems. It seems quite sturdy when not in use, but in use it rotates. I am probably gonna fix it at some point maybe by cutting a channel or making a flat on the face of the dowel.

I was aiming for a smaller gauge that I could use in places that were too long for my marking gauge.

 

[Chris Knight]

Wiley,
Thanks for the picture, I shall print it and measure the angle. Eyeballing it, I'd say it was about 6 or 7 degrees.

Jesse,
I should be interested to see your gauge when you can post the picture - thank you. My stem will be rectangular in cross section so I shouldn't have any problems with it rotating!

 

[MikeW]

Hi Chris,

If you get Popular Woodworking, there was an issue, perhaps 3-4 back, which had a gauge based upon the one in the Seaton chest.

The magazine had the plans. I can measure the angle if you want. One of the better one-handed gauges I have.

Take care, Mike

 

[Chris Knight]

Mike,

Thanks. I may have that mag - there are several I haven't really had a look at yet - other thing got in the way and I forgot about them!

Your gauge looks nice and I should be interested in the angle - looks about the same as Wiley's picture I think.

 

[MikeW]

Hi Chris,

Mine measures ~5 degrees.

I suspect that Dean Jansa, the person who wrote the article in PopWood [and made mine, meep meep], has the angle in it. I looked on-line to see if PopWood had a PDF of the article, but couldn't find it. If you don't have the issue and want more specifics, let me know and I'll hunt down my copy ['cause it's probably hiding somewhere].

Take care, Mike

 

[JesseM]

Here are some pics of the panel gauge. Like I said I was shooting for a smallish gauge that I could use for medium length markings. The rod is 18". The length x height x width is 6 x 3 x 1 approximately, all lengths a bit more. The angle on the wedge is ~10 degrees. The smaller curved end on the wedge is bigger than the rear mortise so that it can't come through without removing the rod.

And see even the cats approve. Just an extra pic in the camera:

As I mentioned though its a failed gauge because the dowel rotates in use. I'm going to try and fix or build another just like it with a square rod.

 

[MikeW]

Hi Jesse,

fwiw, the vintage panel gauges I use have a flat bottom, sides square to the bottom and a radiused top that the pressure shoe pushes on. But a wedge-based like yours would work as well.

Take care, Mike

 

[Wendell]

I looked up the plans for Dean Jansa's marking gauge in Dec '06 issue of PW. Interestingly he doesn't specifically indicate the wedge angle, only linear dimensions are marked. The angle of the mortice for the wedge works out to be approximately 3.8 degrees. For the wedge, I calculate the angle to be about 5.2 degrees which is close to what Mike measured. So here's a question, why don't the two angles match? Is this by design?

Wendell

 

[JesseM]

Hi Jesse,

fwiw, the vintage panel gauges I use have a flat bottom, sides square to the bottom and a radiused top that the pressure shoe pushes on. But a wedge-based like yours would work as well.

Take care, Mike

Yeah the next model will probably have at least a square rod. I don't wanna get too difficult. Though the radiused top would be nice.

 

[Wiley Horne]

Hi Chris and All,

Just a followup note. I make the D. Malloch sash fillester wedge to be 5-1/2 degrees. I also checked a Clark & Williams wedge arm plough that locks up real well, and make it to be 6 degrees. The Malloch has a particularly positive lock up to light hammer taps.

It occurs to me that if Mike's 'Seaton chest-alike' gauge made by Dean Jansa really does have a 5 degree wedge, then it would lock up on thumb pressure alone. Is that right, Mike?

Also trying to get my head wrapped around whether it would matter (in selecting a wedge angle) whether the wedge is on the same axis as the stem, or at right angle to the stem, as in Mike's gauge.

Wiley

 

[MikeW]

Hi Wendell,

I cannot find my copy, and assume your measurements are correct. As such, I have no idea why the difference exists, other than so say it is probably not important in the length involved.

In looking at a couple of my other wedged gauges, I also do not believe they match exactly because of the rub patterns on the beams and wedges.

This version of the Seaton gauge Dean made for me does lock precisely and very strong with little pressure. Kinda hard to tell whether it is more "accurately" fit or not without messing with chalk for checking for an even rub pattern--or waiting for a few more years of use for it to make itself evident.

Take care, Mike

 

[Chris Knight]

Mike, Jesse, Wiley, Wendell,

Many thanks for the info - I shall go with 5 degrees I think. I have no idea if the fact that the wedge is at right angles to the mortice gauge makes any difference in practice - I have tried to imagine the friction and forces involved but can't see where there would be a big difference in results.

 

[bugbear]

I think I heard 10 degrees was optimum

Probably varies with timber and purpose, I'd guess.

Here's an answer to a similar question.

http://nika.frontier.iarc.uaf.edu/~cswi ... =1#message

BugBear

 

[Chris Knight]

Paul,
Thanks for that. I will hope my paring skills are up to it!

 

[JesseM]

I think I heard 10 degrees was optimum

Probably varies with timber and purpose, I'd guess.

Here's an answer to a similar question.

http://nika.frontier.iarc.uaf.edu/~cswi ... =1#message

BugBear

Thanks for that. My wedge is not optimum. It holds fairly well, but I will probably lower the angle to ~5 on version 2.0.

 

[Chris Knight]

The 5 degrees seems about right, I can easily tighten or release it with one hand and when tight, the stock stays put. I think that a slightly smaller angle might be better still but I am happy with this.

 

[Frank D.]

Looks very nice Chris!
What did you use for the blade? What shape did you decide on? It looks like a disk but it's hard to tell for sure.

 

[Philly]

Looks good, Chris. Is that you're new shooting board in the background?
Cheers
Philly