Boy do I need Jerrys manual-rookie domino question

[maxrpierce]

Making mitered raised panel cab doors- 2.5" stiles /rails 3/4 stock
What is your opinion of the correct domino size and depth and amount?
Sorry for my rookiness any advice appreciated

 

[bill-e]

The largest Domino tenon is 10mm and that's about 3/8" which is a pretty standard sized tenon.  So I'd use either the 10x50 or the 8x40 tenon.

 

[woodshopdemos]

The discussion so far is good and appropriate but you had better consider length as well. You a re going across the miter so placement is almost more important than thickness. I suggest you lay each of the D. tenons across the joint and make that a part of your selection. The mortises for this tenon also have to dodge whatever shape is profiled into the stock and panel groove.  While having a tenon one third the stock thickness is the rule of thumb, the thickness here may not be the 3/4" that you are thinking.  In my thinking, the 5mm X 30mm may be exactly right for this application.

 

[Matthew Schenker]

The mortises for this tenon also have to dodge whatever shape is profiled into the stock and panel groove.

Good point John!  I haven't done this yet with the Domino, but your comment brings back fond memories of projects where I thought I was all set centering a biscuit in the thickness, only to remember that I am going to rout a profile!!!

Matthew

 

[maxrpierce]

thanks for the input- I will play with it today and hopefully answer some of my own uneducated questions-
Last question - One tennon, two tennons ? (again I haven't got to lay them out so It may be obvious but my mind isn't converting 8x50 into 2.5 inches just yet) thanks again

 

[woodshopdemos]

Same answer. The joint will show what you can do. Lay the D. tenon over the joint. It is very  unlikely you will get or need double tenons. Keep it simple. 
  If anyone reading this thinks that having only one 5mm tenon isn't that much different than having a biscuit... WRONG.  The Domino tenon is tight in both directions. A biscuit has "slop" in the left and right direction that is why is is useful in aligning boards but not serve as a mortise and tenon.
  I have a completed 24" base cabinet that has 5mm D. tenons every 5 inches and it was dry fit together and stayed together even though we were still working on slides, doors and drawers. We had to use a rubber mallet to break it down for gluing up.

 

[maxrpierce]

Thanks gentlemen for your input!
After a couple of scary minutes and frantic trip to Woodcraft I successfully found out that both of you are correct. The 6x40 was perfect even after checking profiles and grooves for panels (as John wisely mentioned)- although the 5x30 did also work in my mind didn't feel quite as stong-

 

[Jerry Work]

Hi,

Good question.  As others have stated, conventional wisdom is to use a tenon about one third the material thickness when using a single tenon.  Working with my industrial slot mortiser for years and with Dominos most recently I have found I like a thicker loose tenon than I use with cut in place tenons.  I now use more in the order of one half the material thickness with one loose tenon.  The Domino fits tightly into the mortise and features a number of stamped in glue pockets quite unlike the slick tenon walls on cut-in-place tenons.  Since the shoulder is just the end cut on the work piece it is nearly always flat and square, again unlike many cut-in-place tenons with poorly formed shoulders, so it appears to me that the shoulder generally plays a greater role in adding strength to a loose tenon than to a cut-in-place tenon.  As a result a bending force trying to fracture a loose tenon joint is more directly translated into a pulling force on the tenon to wall glue joint and this is where the Domino seems to really stand out from my experience.  A thicker tenon I believe provides more resistance to any twisting force on the joint as well.  So, the real issue is likely whether the relatively thinner wall from the edge of the tenon to the edge of the work piece is more fragile than the thinner tenon.  By using a tenon half the material thickness then the combined thicknesses of the two walls equals the thickness of the tenon.  By my logic this seems to be a good comprimise and it is the one I use.  I can't remember ever experiencing a loose tenon joint failure using this standard.  Doesn't mean it really is stronger, only that it has been plenty strong enough so far.  Where I depart a bit from this is when I place a loose tenon inside a tongue and grove joint to align and strengthen it.  A good example is a rail and stile frame.  Independent of the profile used (if any, I rarely use any profile as I like the look better) the tongue must be the same length as the depth of the panel groove.  I use a 10mm x 10mm grove for most of my work and the strength of that joint is increased imeasurably by the addition of a loose tenon.  I prefer to put in an 8mm, rather than 10mm tenon to avoid any issue of exactly centering on the groove.  If I am off a bit the joint still makes, it is just that one tongue edge to tenon wall will be a bit over 1mm while the other will be a bit less.  No harm, no foul.  Bottom line for me is no failures in a lot of use.  I also find two tenons across a joint to be much stronger than one.  If the work piece thickness is 3.5x the domino thickness then I use two, each centered one tenon thickness down from each workpiece edge.  If the workpiece is 5x the tenon thickness or more then I set the two tenons 1.5x the tenon width down from each edge, a spacing equivilant to the conventional one third the work piece thickness.  Hope this helps.

Jerry

Making mitered raised panel cab doors- 2.5" stiles /rails 3/4 stock
What is your opinion of the correct domino size and depth and amount?
Sorry for my rookiness any advice appreciated

 

[maxrpierce]

Thank you Jerry,
I just learned as much by reading your input than I would have by experimenting for hours and wasting valued Domino tenons.
All of your input is appreciated more than you probably know.

 

[Corwin]

Hope this helps.

Jerry

No question in this regard!  Thanks for covering this topic.  Great to have things all spelled out, so to speak.

Corwin