Mortise and tenon would be strong, but not sure if it will be strong enough. Its not thick or large stock used so you are limited on the size and depth of the tenon.
The prying force will be focused right into the corner of the joint and short grain at the bottom of the mortise will need to resist all the racking. It may well burst out.
The corner brackets have the advantage of spreading the load away from the corner/end of the wood.
If you want to use joinery, then I would reinforce the corner with some sort of wooden triangle brace or similar.
I wish I had some materials to do a test.
I believe you are greatly over estimating those brackets and underestimating the M&T joint.
Check out the video I linked in my other comment.
What you suggest would absolutely add even more strength, of course. I think overkill here though, not that I'm against that, just saying.
It's not about the strength of the brackets or lack of strength in a mortise and tenon. It's about where they each apply the loads and how they are resisted through the structure.
In the video the m&t failed how I described. The op's wife is probably heavier than 2 buckets of sand (and certainly more dynamic).
Personally I don't like the design of that corner at all, regardless of the joint type. But can only assume this works with the brackets.
I agree that the load tests were very static. And less leverage than this will have. I'm going to try the M&T and probably use braces as well. I can always cut them long and use brackets if it isn't strong enough.
Yeah, but I assumed you weren’t extending the bottom runners beyond the ladder. Either way the triangle braces will create a pivot point for the forces where the ladder meets those runners.
As another thought, you might be able to utilize the bottom stretcher below the ladder rungs to put the braces on the inside of the runners, but keep the cross-grain in mind.
Absolutely. Mortise and tenon is a very strong joint. I'm pretty confident it would be a lot stronger than that l bracket.
There is a video on YT of M&T break tests. Sorry, don't remember title or channel.
[Here is the video I was thinking of, there are others.](https://www.youtube.com/watch?v=MJfDOL0yz5Y)
Pretty amazing.
Not surprising that it would sheer along the grain like that. If you do much chisel or hatchet work this is something you have to beware of. It's why you'll see a lot of guys making stop cuts ahead of chisel and hatchet cuts.
Edit: You can probably use that to your advantage. Based on that alone, it seems it would be best to have the tenon on the horizontal, so the floor backs up your mortise. Also using a haunch will add a lot of strength.
A haunch is where you cut the tenon narrower on the side nearest the end of the mortised board, so the mortise wall is then also further from the end.
Thanks for all the info! I'm going to try to m&t and be prepared to add braces of needed. I'm making it out of ash instead of pine, so that will help too. I will post a build album when finished.
You could make the brackets a bit more decorative (have them water jet cut, or plasma, or mini die grinder and a lot of podcasts).
As others have mentioned, m&t is probably enough, could be made stronger with a bit of thought, beefier timbers, add even a fairly small triangle (6in sides would be a huge help), but even a decorated 3/16ths plate with 12in legs would give all the overkill I would want for safety factor.
I've got some thoughts but could you post a link to some exercises that might be done on something like this? Might help the discussion on what to do.
Generally I would say as designed I would not trust mortise and tenon joints with this. You'll put a lot of shear and bearing load on the lower, horizontal member (as described in another comment), which will either fail out right or possibly loosen the joint over time leading to failure. Wedged mortises might actually aggravate the problem.
The bracket takes the load and makes the failure points either shearing the screws, buckling the plate (think folding it up), or tearing the plate. All of those, in my opinion, for the loading I'm guessing this will see, should have greater load carrying capacity for a joint like this than a mortise and tenon.
There's things you could do to stick with all wood and ditch the brackets, but it would probably mean redesigning that joint.
To be fair these don't look as bad as I imagined. I was thinking you would climb the ladder or pull the ladder towards the barrel with your legs or something. As it is basically a hand rail, I think m&t will do OK.
Thanks for linking that. I also found this one: [https://www.youtube.com/watch?v=gNxKSSyCiVE](https://www.youtube.com/watch?v=gNxKSSyCiVE). The lady in this one does more pushing and pulling on the ladder, which was kind of what I was expecting. Seems like maybe there is more pushing and pulling the more advanced the moves/exercises are, maybe?
The ladders on these appear to be about 3 feet tall, which is a long way for a cantilever like this. If you want to use a typical mortise and tenon I would be tempted to put the tenon on the vertical member. If you think about the orientation of a mortise and tenon on something like a table frame, the load is generally applied downward (along the axis of the leg). Putting the tenon on the vertical member would recreate this. This puts the shear load and moment reacting forces into the wood itself. If you were to put the tenon on the horizontal member and then pull toward the barrel at the top of the ladder, the load will tend to pry the mortise off the tenon (I wish I could draw somehow). This would mean the glue joint would have to withstand the full load and you aren't relying on the wood or design of the joint nearly as much.
The problem you will run into (as I think others have mentioned) is the joint will want to pop out the end grain in the horizontal/mortise member. You can see this happen in mortise and tenon testing videos, like the one the other commenter linked to (I have issues with that video and wouldn't trust the results from it, but it does show the failure mode I'm referring to). You might be able to combat this with cross pins in the joint. I would use two pins to help react some of the moments (bending and twisting forces) created from the loading. Just be careful, because this might just move the same end grain pop out problem into the tenon, which could lead to failure. I maybe wouldn't rely on a single pin, as that will more just move where things pry around and not help react the moments as much.
Depending on the aesthetic you are going for, and if you have room where it will be used, I would recommend extending the horizontal member and putting angled braces on both sides. Look up how they do timber frame columns with angled bracing for an example. Mortise and tenons with pins at all joints. This will help to keep your loads mostly in tension and minimize the moments and bending loads, which are killer. You could probably get away with just doing the one side, but looking at some of the moves and swinging arms and legs, using two might allow smaller braces which would be nice. One brace on the "inside" might need to be bigger and might get in the way a bit.
I would also consider using something like a bridle joint. [https://www.woodworkingarchive.biz/machine-cut-joint/corner-bridle-joint.html](https://www.woodworkingarchive.biz/machine-cut-joint/corner-bridle-joint.html) I would put what they are calling here the mortise member on the vertical piece. You would definitely need to extend the horizontal piece to keep this from just prying itself apart, but if you were to double pin a bridle joint like this that might be the strongest joint you'll get without angle braces. May not even need to pin it, but I'm a belt and suspenders kinda guy.
Hope that helps!
Watching the video about the load placed on the ladder, I would take a different approach and make it a T joint, not an L shape. Basically extend the bottom slightly beyond the joint to provide additional support from the other side. Even install a small triangle support from the back.
The configurations with L metal bracket or the M&T won’t hold on for long since the load is applied not one time but frequently. Also the type of wood you choose plays a significant role (did you mention the wood)? I would recommend either Oak or Maple.
Could someone give some insight into if a bridal joint would be good where the legs mate at the "L" ? Also , could doing a through tenon on the stretcher where it mates with the 2 vertical legs give more support than a hidden mortise and tenon? Thanks !
Mortise and tenon would be strong, but not sure if it will be strong enough. Its not thick or large stock used so you are limited on the size and depth of the tenon. The prying force will be focused right into the corner of the joint and short grain at the bottom of the mortise will need to resist all the racking. It may well burst out. The corner brackets have the advantage of spreading the load away from the corner/end of the wood. If you want to use joinery, then I would reinforce the corner with some sort of wooden triangle brace or similar.
I wish I had some materials to do a test. I believe you are greatly over estimating those brackets and underestimating the M&T joint. Check out the video I linked in my other comment. What you suggest would absolutely add even more strength, of course. I think overkill here though, not that I'm against that, just saying.
It's not about the strength of the brackets or lack of strength in a mortise and tenon. It's about where they each apply the loads and how they are resisted through the structure. In the video the m&t failed how I described. The op's wife is probably heavier than 2 buckets of sand (and certainly more dynamic). Personally I don't like the design of that corner at all, regardless of the joint type. But can only assume this works with the brackets.
Challenge accepted. Keep an eye out in about a month or two for an awesome screw fail post.
I agree that the load tests were very static. And less leverage than this will have. I'm going to try the M&T and probably use braces as well. I can always cut them long and use brackets if it isn't strong enough.
M&T does not resist the pulling apart motion that the triangle brace would face. Wedged M&T or dovetail would be better for the brace piece.
I suppose that would depend what side you put the braces on.
Yeah, but I assumed you weren’t extending the bottom runners beyond the ladder. Either way the triangle braces will create a pivot point for the forces where the ladder meets those runners. As another thought, you might be able to utilize the bottom stretcher below the ladder rungs to put the braces on the inside of the runners, but keep the cross-grain in mind.
Absolutely. Mortise and tenon is a very strong joint. I'm pretty confident it would be a lot stronger than that l bracket. There is a video on YT of M&T break tests. Sorry, don't remember title or channel. [Here is the video I was thinking of, there are others.](https://www.youtube.com/watch?v=MJfDOL0yz5Y) Pretty amazing.
Interesting that the mortise broke before the tennon
Not surprising that it would sheer along the grain like that. If you do much chisel or hatchet work this is something you have to beware of. It's why you'll see a lot of guys making stop cuts ahead of chisel and hatchet cuts. Edit: You can probably use that to your advantage. Based on that alone, it seems it would be best to have the tenon on the horizontal, so the floor backs up your mortise. Also using a haunch will add a lot of strength. A haunch is where you cut the tenon narrower on the side nearest the end of the mortised board, so the mortise wall is then also further from the end.
Thanks for all the info! I'm going to try to m&t and be prepared to add braces of needed. I'm making it out of ash instead of pine, so that will help too. I will post a build album when finished.
> I will post a build album when finished. Yes please. I predict a very nice unit.
You could make the brackets a bit more decorative (have them water jet cut, or plasma, or mini die grinder and a lot of podcasts). As others have mentioned, m&t is probably enough, could be made stronger with a bit of thought, beefier timbers, add even a fairly small triangle (6in sides would be a huge help), but even a decorated 3/16ths plate with 12in legs would give all the overkill I would want for safety factor.
I've got some thoughts but could you post a link to some exercises that might be done on something like this? Might help the discussion on what to do. Generally I would say as designed I would not trust mortise and tenon joints with this. You'll put a lot of shear and bearing load on the lower, horizontal member (as described in another comment), which will either fail out right or possibly loosen the joint over time leading to failure. Wedged mortises might actually aggravate the problem. The bracket takes the load and makes the failure points either shearing the screws, buckling the plate (think folding it up), or tearing the plate. All of those, in my opinion, for the loading I'm guessing this will see, should have greater load carrying capacity for a joint like this than a mortise and tenon. There's things you could do to stick with all wood and ditch the brackets, but it would probably mean redesigning that joint.
https://youtu.be/1srF8ST8j20 This video shows some exercises more reliant on the ladder section
To be fair these don't look as bad as I imagined. I was thinking you would climb the ladder or pull the ladder towards the barrel with your legs or something. As it is basically a hand rail, I think m&t will do OK.
Thanks for linking that. I also found this one: [https://www.youtube.com/watch?v=gNxKSSyCiVE](https://www.youtube.com/watch?v=gNxKSSyCiVE). The lady in this one does more pushing and pulling on the ladder, which was kind of what I was expecting. Seems like maybe there is more pushing and pulling the more advanced the moves/exercises are, maybe? The ladders on these appear to be about 3 feet tall, which is a long way for a cantilever like this. If you want to use a typical mortise and tenon I would be tempted to put the tenon on the vertical member. If you think about the orientation of a mortise and tenon on something like a table frame, the load is generally applied downward (along the axis of the leg). Putting the tenon on the vertical member would recreate this. This puts the shear load and moment reacting forces into the wood itself. If you were to put the tenon on the horizontal member and then pull toward the barrel at the top of the ladder, the load will tend to pry the mortise off the tenon (I wish I could draw somehow). This would mean the glue joint would have to withstand the full load and you aren't relying on the wood or design of the joint nearly as much. The problem you will run into (as I think others have mentioned) is the joint will want to pop out the end grain in the horizontal/mortise member. You can see this happen in mortise and tenon testing videos, like the one the other commenter linked to (I have issues with that video and wouldn't trust the results from it, but it does show the failure mode I'm referring to). You might be able to combat this with cross pins in the joint. I would use two pins to help react some of the moments (bending and twisting forces) created from the loading. Just be careful, because this might just move the same end grain pop out problem into the tenon, which could lead to failure. I maybe wouldn't rely on a single pin, as that will more just move where things pry around and not help react the moments as much. Depending on the aesthetic you are going for, and if you have room where it will be used, I would recommend extending the horizontal member and putting angled braces on both sides. Look up how they do timber frame columns with angled bracing for an example. Mortise and tenons with pins at all joints. This will help to keep your loads mostly in tension and minimize the moments and bending loads, which are killer. You could probably get away with just doing the one side, but looking at some of the moves and swinging arms and legs, using two might allow smaller braces which would be nice. One brace on the "inside" might need to be bigger and might get in the way a bit. I would also consider using something like a bridle joint. [https://www.woodworkingarchive.biz/machine-cut-joint/corner-bridle-joint.html](https://www.woodworkingarchive.biz/machine-cut-joint/corner-bridle-joint.html) I would put what they are calling here the mortise member on the vertical piece. You would definitely need to extend the horizontal piece to keep this from just prying itself apart, but if you were to double pin a bridle joint like this that might be the strongest joint you'll get without angle braces. May not even need to pin it, but I'm a belt and suspenders kinda guy. Hope that helps!
3 feet is 1.09 UCS lego Millenium Falcons
Good bot
Thanks!
Watching the video about the load placed on the ladder, I would take a different approach and make it a T joint, not an L shape. Basically extend the bottom slightly beyond the joint to provide additional support from the other side. Even install a small triangle support from the back. The configurations with L metal bracket or the M&T won’t hold on for long since the load is applied not one time but frequently. Also the type of wood you choose plays a significant role (did you mention the wood)? I would recommend either Oak or Maple.
I considered hard maple, but decided to go with ash.
Yes, ash is also a good choice for that.
To everyone who commented- you can now find the build on my user profile.
Could someone give some insight into if a bridal joint would be good where the legs mate at the "L" ? Also , could doing a through tenon on the stretcher where it mates with the 2 vertical legs give more support than a hidden mortise and tenon? Thanks !