Question: how to set angle with side-clamping jig

Re: Question: how to set angle with side-clamping

Derek Cohen (in Perth Australia)

>Andy

The easiest way to set it up for 38 degrees is to draw this angle on a piece of cardboard, then line up the blade and guide alongside it. Extend the blade until the angles match.

Regards from Perth

Derek

Re: Question: how to set angle with side-clamping

bill tindall

>In theory you could use a cosine function presuming this distance setting is indeed the hypotenuse of a right triangle bounded by the point the wheel touches the stone, the tip of the iron (and this is the questionable part) the place on the jig you are measuring from. In this case cosine 38 degrees (look up in table) equals length from wheel contactpoint on the stone to iron tip, divided by length of tip to jig measuring point. If the measuring point on the jig does not define a right triangle (90 degrees angle between iron and point from jig to wheel contact point, or to put another way if the mounted iron is placed parallel to the plane of the stone is the jig measuring point directly above the wheel contact point? If not then this simple approach will not work) the problem still can be solved but it is more involved than I can describe in a few words.

Therefore, cut a 38 degree angle on a stick the thickness of the iron, mount in jig and determine empirically the distance setting. Or mount iron and use angle gague to adjust iron to 38 degrees.

Re: Question: how to set angle with side-clamping

VTAndy2

>Hi Derek,

Thanks for the quick response.

While we're on the bevel topic. For a 38 degree bevel on your low-angle planes (giving you 60 1/2 degrees total) do you make the primary bevel 38 degrees or is the primary 25 and the secondary 38?

Thanks,

Andy

Re: Question: how to set angle with side-clamping

VTAndy2

>Bill wrote:

"Or mount iron and use angle gauge to adjust iron to 38 degrees."

Now we're talking. I don't have an angle gauge but that does seem to be the simplest solution.

Re: Question: how to set angle with side-clamping

Derek Cohen (in Perth Australia)

>For a 38 degree bevel on your low-angle planes (giving you 60 1/2 degrees total) do you make the primary bevel 38 degrees or is the primary 25 and the secondary 38?

Andy

With low angle/bevel up planes the cutting angle is additive, that is, the bed angle plus the final bevel angle. If your bed angle is the typical 12 degrees, then a 38 degree bevel will give you a 50 degree cutting angle. Is this what you want? Or, if you want a 38 degree cutting angle, the bevel angle needs to total 26 degrees.

The secondary microbevel is to reduce the amount of honing needed. It does not matter what grit you hone the primary bevel. The important bevel is the final one, and it is this that requires the best you can manage.

Since you are going to be adding a microbevel (secondary bevel) at the end, make the primary the largest common angle you can fit before a 1 or 2 degree microbevel. For example, a 26 degree bevel = a 25 degree primary and a 1 degree secondary. This is easy to do if you have a Veritas Honing Guide (either Mk I or II). On a Eclipse-type, as you have, you will need to calculate the angles. For 38 degrees try a 35 degree primary and a 3 degree secondary. Ironically, this cannot be done on the Veritas (which sells irons with 38 degree bevels), as the Guides offer either 1 or 2 degree microbevels. So you either go to 37 degrees (12 bed +35 primary +2 secondary = 49 degree cutting angle) or 41 degrees (12+ 40 + 1 = 53 degree cutting angle).

Regards from Perth

Derek

I noticed that about the MK II too

Denis Ch�nard, Orl�ans, Ont.

>One way to do it is to use the 50 degree mark from the red scale, and set the jig on the yellow scale. By eye it gives about 37 degrees, so with a 1 degree micro-bevel you get 38.

I think there was just not enough space on the jig to write all the markings...

DC

how to set 38 degrees

bill tindall

>well you forced me to get out a trig table........ Cosine 38 degrees is 0.7880. I included 4 significant figures because I appreciate how precise planing enthusiasts are (snicker).

You can lay out a 38 dgree cut on a board, cut it and then use the cut piece to place between iron and stone and diddle with distance until angles match. this angle gague needs to have a hypotenuse ( the part parallel to the plane iron) 1" long and the long side (side parallel to the stone) 0.7880 inches long. Of course these can be scaled 1X" by 0.7880X inches.

Or use tangent function. In this case for 38 degrees the rise(height of gague block) is 0.78 and the run (length along stone) is 1.00.

I wouldn't need to do this more than once before I bought an inexpensive angle gague.

Re: Question: how to set angle with side-clamping

Peter Evans

>Using Trig (and the credit for the spreadsheet is Gary Heald in Furniture & Cabinetmaking Issue 87) the numbers are:

38 degrees bevel angle

Width of iron 2 2.4 2.8 3.1 3.6 4.8

extension in mm 23.9 24.4 25.0 25.3 26.0 27.5

I will leave the conversion to inches to you.

Cheers

Re: Question: how to set angle with side-clamping

VTAndy2

>Thanks to Bill and Peter for their responses.

-Andy

Re: Question: how to set angle with side-clamping

Rob Lee

>Hi Andy -

The exact angle really doesn't matter - repeatability is what you're after.

I'd suggest...

1) Set your blade in the guide, at the angle you want (say 35 degrees).

2) Press the face of the guide against a scrap piece of wood, with the blade laying flat on the wood (bevel up)

3) Mark or score a line on the board - now you have a projection jig for 35 degrees...

4) Mark or score a second line 1mm or so short of the first mark - and use that as your micro-bevel projection setting

Using this approach, you should be able to handle most of your sharpening angle requirements with 3-4 different angle settings, on a single scrap of wood...

Cheers -

Rob