Double Mortise

[Guest Mahoganus]

Is there technical name for double countersunk mortises like these in my video? These joints that Greene and Greene did are ingénues. They are awesome I can cheat on the length and still end up with the best fit in the world.

http://www.youtube.com/watch?v=N6POhCodU5I

[NYHump]

Way cool!

And just another reason I should get a bridgeport mill!

Damn machinists........

[Guest Mahoganus]

Way cool!

And just another reason I should get a Bridgeport mill!

Damn machinists........

Thanks,, yeah after having the Bridgeport with digital readouts on it,, I could never go back. I bought my J head Bridgeport used witch is a 1980 for 2800.00 including tax.

Compared to some of the other wood working machines I bought,, very comparable.

I use all my router bits in it no problem, its quiet, dead accurate, can drill - bore, etc well worth it to me and I wish I would have bought the Bridgeport years ago rather than the money I spent on my new shaper which pretty much sits there unless I need to run off a huge raise panel like the ones in my man doors and I'm pretty sure I could run those off on the Bridgeport as well with a slight mod to the table.

The biggest thing I have noticed is the sacrifice time. The wood tools are fast but alot less accurate, The mill seems a little slower but everything is dead on to the +/- .001

Something else odd I noticed,, with steel for a nice slip fit +.005 for wood +.010 and even then its tight.

Another question that comes to my mind to,, is it possible to have to good a fit,, will the joints swell so tight it might crack the wood?

Time will tell

[Onboard]

Is there technical name for double countersunk mortises like these in my video? These joints that Greene and Greene did are ingénues. They are awesome I can cheat on the length and still end up with the best fit in the world.

I'm with NYHump, when I saw the Bridgeport mill, I thought how can Powermatic compete with that!

As far as the "double countersunk mortise" the closest thing I can think of is called a Housed Mortise and Tenon joint. The housed mortise is typically the same size as the end of the board (no tenon). In this case he created a standard tenon on the end, cut a standard mortise and then removed waste centered around the mortise to allow the full size of the end of the board to be pushed part way in as well which would make it housed. So I guess you could call it a modified housed mortise or maybe double housed mortise.

I’m sure we have community members who know exactly what this is called, so hopefully one of those members will read this post and leave a comment.

[Guest Mahoganus]

I'm with NYHump, when I saw the Bridgeport mill, I thought how can Powermatic compete with that!

As far as the "double countersunk mortise" the closest thing I can think of is called a Housed Mortise and Tenon joint. The housed mortise is typically the same size as the end of the board (no tenon). In this case he created a standard tenon on the end, cut a standard mortise and then removed waste centered around the mortise to allow the full size of the end of the board to be pushed part way in as well which would make it housed. So I guess you could call it a modified housed mortise or maybe double housed mortise.

I’m sure we have community members who know exactly what this is called, so hopefully one of those members will read this post and leave a comment.

Thanks OnBoard! At least now when I goggle housed mortise I get results Im looking for.

Hopefully they will stop by with there input.

[Onboard]

Thanks OnBoard! At least now when I goggle housed mortise I get results Im looking for.

Hopefully they will stop by with there input.

After posting I noticed your second post. You might find this man's site of interest.

http://woodgears.ca/ - Woodworking for engineers.

http://woodgears.ca/mortise/accuracy.html - Here he discusses Mortise & Tenon accuracy.

If there’s a video, it's typically at the bottom of each page.

[Guest Mahoganus]

After posting I noticed your second post. You might find this man's site of interest.

http://woodgears.ca/ - Woodworking for engineers.

http://woodgears.ca/...e/accuracy.html - Here he discusses Mortise & Tenon accuracy.

If there’s a video, it is typically at the bottom of each page.

wow! Thanks alot thats what I have been looking for!

[iSawitFirst]

Im not sure I understand the reason for this type of joint. If the spindle shrinks a gap will show. If it expands, cracking may result. Help me out here.

[Guest Mahoganus]

Im not sure I understand the reason for this type of joint. If the spindle shrinks a gap will show. If it expands, cracking may result. Help me out here.

I suck at explaining why,, I tried to in this video for ya but I dont think I made much sense.

http://www.youtube.com/watch?v=ZR-OSfWEZzM

[iSawitFirst]

Wow! Great explanation and the bed looks super. I think I see your point about what would happen if the tenons are too long but that's what dry fit is all about; to find those types of problems. I don't know. It just seems like a lot of work for the same result. Maybe I need to see it in person to fully appreciate it.

I have to commend you though, on your precision. I've never seen such tight joinery. As long as it stays that way I'd say you've got a winner.

[Bobby Slack]

Bob Lang on his book "Shop Drawings for Greene & Greene Furniture" page 23 calls them "Housed Mortises". This is the way to go! Nice pictures. I used to sell Lagun milling machines, same type of machines, just made in Spain. Unfortunately most of these machines today are made with Chinese castings.

[wleingang]

Thanks for sharing this, and very nice work! I always wondered what those were called, I was considering doing those on a patio railing I am going to make... just never saw them demonstrated so I figured I was crazy. That bed is going to look hot!

[Gregory Paolini]

I've heard of a few different names for the joint - Most often it's refered to as a Housed somthing or other... Sometimes a Housed Mortise; but accually it's more of a housed tennon.

The pro of the joint is that workpiece length is not critical, which is especcially nice for corved work such as back slats on chairs. The con of the joint is, on wider work pieces, the slat can contract, and show a gap - Although this isn't too much of an issue unless you have slats in excess of 4 inches.

Hope this helps,

Gregory