Tips for paring dovetail lap lines like shown in Kirby

[Tony Wilkins]

After rereading Kirby, I decided to try his saw, vertical pare, and then horizontal pare out the waste method. After trying it, it looks like I have a small hump across the baseline in all of them — at least as far as my big square can tell.*

Tips for getting completely flat? Anybody tried this method?

*I’m really tempted to get a 4” square with one of those Sterling Dovetailing Rules.

[Derek Cohen]

Tony, I am not clear on what you are saying. What is a "hump"? Assuming that you mean that the baseling is not coplanar and has a high/low spot ... (1) check the end of the board is perfectly straight before you mark it out, (2) undercut the baseline before clearing the waste with a chisel to prevent it driving back over the line. And (3) check that your square is square.

Incidentally, there is a 2014 thread on WoodCentral where you first mentioned reading and using Kirby's method. Lots of discussion there. I am not permitted a link here (so silly), but find it as there is a lot of discussion.

Regards from Perth

Derek

[Tony Wilkins]

Tony, I am not clear on what you are saying. What is a "hump"? Assuming that you mean that the baseling is not coplanar and has a high/low spot ... (1) check the end of the board is perfectly straight before you mark it out, (2) undercut the baseline before clearing the waste with a chisel to prevent it driving back over the line. And (3) check that your square is square.

Incidentally, there is a 2014 thread on WoodCentral where you first mentioned reading and using Kirby's method. Lots of discussion there. I am not permitted a link here (so silly), but find it as there is a lot of discussion.

Regards from Perth

Derek

I wish I remembered when and where I asked question lol.

[Mark Rainey]

After rereading Kirby, I decided to try his saw, vertical pare, and then horizontal pare out the waste method. After trying it, it looks like I have a small hump across the baseline in all of them — at least as far as my big square can tell.*

Tips for getting completely flat? Anybody tried this method?

*I’m really tempted to get a 4” square with one of those Sterling Dovetailing Rules.
I use Kirby’s method for dovetails & yes, after horizontal paring I usually still have small humps. I just do more horizontal paring starting right at the baseline & sometimes even undercut towards the center.

[John Schtrumpf]

I wish I remembered when and where I asked question lol.

I believe Derek is referring to a discussion you will find if you search for (include the quotes):

"Surprises from Ian Kirby's Dovetail book"

And I slightly undercut towards the center, when paring the baseline.

[Mike Henderson]

After rereading Kirby, I decided to try his saw, vertical pare, and then horizontal pare out the waste method. After trying it, it looks like I have a small hump across the baseline in all of them — at least as far as my big square can tell.*

Tips for getting completely flat? Anybody tried this method?

*I’m really tempted to get a 4” square with one of those Sterling Dovetailing Rules.

I'm not sure if this is exactly what you're talking about for the Sterling Rule, but he makes a very small "blade" that you put into a double square (such as the iGaging or PEC) and you can use that to check whether the sides of the tails are square, as well as whether you have a "hump" in the base. If you already have a double square, the blade is $25 (when I bought one). Well worth it for dovetail work.

Like others, I usually cut a very slight convex in the base just to make sure there's no hump. A hump will keep the two pieces from fitting together properly and show a gap on both side at the base.

Mike

[Tony Wilkins]

I believe Derek is referring to a discussion you will find if you search for (include the quotes):

"Surprises from Ian Kirby's Dovetail book"

And I slightly undercut towards the center, when paring the baseline.

I found it

[Prashun Patel]

I suspect that even if you hold the chisel perfectly vertical it is driven away from the base when there is so little support on the other side even though that’s the bevel side.

Lee Valley Tools make a nice small square for checking square in tight spaces. Not expensive.

Personally I think you should learn how to pare perfectly vertical, THEN pare a hollow.

[Jim Koepke]

I suspect that even if you hold the chisel perfectly vertical it is driven away from the base when there is so little support on the other side even though that’s the bevel side.

Lee Valley Tools make a nice small square for checking square in tight spaces. Not expensive.

Personally I think you should learn how to pare perfectly vertical, THEN pare a hollow.

+1 on the small Lee Valley square:

http://www.leevalley.com/us/wood/page.aspx?p=72730&cat=1,42936,42941&ap=1

You may also want to consider making a couple of skew chisels from some inexpensive 1/4" chisels. They were used in this project:

https://sawmillcreek.org/showthread.php?259750

The skew chisels appear in the 11th post if your viewing is set to linear view.

jtk

[lowell holmes]

Does your wood have cross grain bow in it. That might manifest it in issues like you describe.

[Tony Wilkins]

Does your wood have cross grain bow in it. That might manifest it in issues like you describe.

No bow particularly. This is the first time I tried horizontal paring like this really. I’ll keep at it and see what goes. Think I should have left more of a distinct baseline to reference off of.

[Mike Henderson]

I suspect that even if you hold the chisel perfectly vertical it is driven away from the base when there is so little support on the other side even though that’s the bevel side.

Lee Valley Tools make a nice small square for checking square in tight spaces. Not expensive.

Personally I think you should learn how to pare perfectly vertical, THEN pare a hollow.

I bought that Lee Valley tool for checking in tight spaces. Couple of problems with it.

1. The dovetail blade is too short. The tool, in itself, is small.
2. They give you a fitted box to put it in but it will only fit if the standard blade is in the handle. So when you go to use it for dovetails, you have to take the standard blade out, put the dovetail blade in (and it's fidley to get in). Then after you use it, you have to take the dovetail blade out and put the standard blade back in or you can't put it back in the case.

Price wise, it's not all that good - it's about $50. You can buy the blade from Sterling Tool Works for $25 and then buy a double square for about the same price (iGaging or PEC blem). I made a storage container for the double square with the Sterling Tool Works dovetail blade in it and use the blade that came with the double square as a rule.

In either case, you want to protect the dovetail blade because both are thin and can be bent - making them useless.

I never use the LV small square with the dovetail blade. I keep it just to show my students what it is but I strongly recommend the Sterling Tool Works solution.

Mike

[I have no affiliation with Sterling Tool Works.]

Added pictures:

Here's a picture of the LV case
402173

Here's the tool stowed in the case. Note that the standard blade is only 2 and 1/2" long. This is the only way you can put it back in the box, with the standard blade in the handle.
402174

Here's the Sterling tool works blade in a double square compared to the LV tool. The small part of the LV blade is 1/2" long. The small part of the STW blade is 1 3/8" long. When you're working with 3/4" material, the LV is too short unless you use some of the blade beyond the small part. But the reason you want a small part is to get into small spaces, especially when making dovetails with the tails very close to each other. For me, the LV tool is just too small.
402175

[Simon MacGowen]

You can buy the blade from Sterling Tool Works for $25 and then buy a double square for about the same price (iGaging or PEC blem). I made a storage container for the double square with the Sterling Tool Works dovetail blade in it and use the blade that came with the double square as a rule.


Mike

[I have no affiliation with Sterling Tool Works.]




I agree with Mike's recommendation (although I do prefer LV's small body design.)

Simon