Face frame alignment
Getting good alignment with mortise and tenon joinery in face frames. December 6, 2000
When making face frames I usually leave the mortises a little wider (1/8") than the tenons for ease of assembly, but sometimes the frame is not as aligned as I want and have to make adjustments. Is that the way most are made, or is it better to try and make the mortise close enough in width that it will only go in one place. If I were doing a lot of the same size, I could use cleats on my bench to line things up, but itís usually several different sizes.
If you can achieve the precision necessary to get accurate alignment with tight fitting tenons (with reasonable effort) then I think you should go for it.
On the other hand, it's fairly easy to push parts into alignment even in complex frames if you allow a bit of space at the ends of the mortises *and* .010" overall clearance between the surfaces of the tenon and the mortise wall. That .010" precision is easy to get since it only depends on your tooling diameter and your initial set-up. If you're using loose tenons in slot mortises you get the .010" when you plane the tenon stock to fit the mortises made by the current mortising bit.
I've built many cabinet doors and entryway doors exactly the way you are doing. I never had a joint failure. With cabinet doors I leave the rails "sticking out" past the stiles, then put them in a clamp. The clamp pushes the rail flush with the stile. I believe the majority of your joint strength comes in the fit between the cheeks of the mortise and tenon.
From the original questioner:
The main trouble I was having was with the middle rails and stiles that separate door and drawer openings. Once they were glued and clamped, it took a lot of force to slide 1/16 one way or the other to balance the openings (yes, I did loosen the clamp before trying to move!) I may have the tenons too thick.
As you are finding out it is important to undersize the tenon .005" - .010" in thickness. We built frames like this for many years with no failures.
What type of glue are you using? Don't use a fast setting glue like Titebond II unless you have more of a mechanical advantage then pipe clamps.
From the original questioner:
It's Titebond! It doesn't give much open time, does it? I didn't think of trying my other glues--guess my brain was stuck in a rut, thanks for the bump out!
Try using Titebond extent--open time is between 5 and 10 minutes.
When it comes to cabinets, I threw my mortising machine out. I use pocket holes--flush every time and you don't have to make all those tenons. The best part is that it takes half as long.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor A:
I use that little beadlock gadget for loose tenons, or sometimes Porter Cable faceframe biscuits. The Beadlock tool will fit in your pocket and will let you fix a tenon that came out wrong. Porter Cable's little biscuits aren't the perfect answer to any one particular question, but they are quick and good for lots of things. I cut biscuit slots with a router about as often as with my biscuit cutter on square stuff, and you will get absolutely flush joints that way. I also use an old time cabinet scraper on occasion, so when the above don't quite come true, I can make it come true.
Comment from contributor N:
Try a #11 biscuit from MLCS. They are a round biscuit the same depth as a #20. You cut the slot with a router-mounted slot cutter. Perfect for face frames.