How deep to cut the lap-joint for joining the wooden beams without the glue?
I bought the glued dried pine wood already. I will use screws because I want to be able to disassemble it easily on demand. I also want to achieve that cross connections are aligned as a straight plane on the top, as shown on the image, so I have no gaps for the top board. That means I need to cut out the beams one into another to achieve it.
The question is, for the marked joint in the middle of the 2.5m (100") beam, what is the optimal depth that I can cut out the lap-joint on each of the beams in order not to weaken too much neither the top or the bottom beam. Should I cut into the middle of the top beam, or go even more, not to weaken the bottom 2.5 (100") beam which needs all the strength? On top will be a loft bed 160cm wide with not more than total 200-300kg of weight. Here are the two examples, which one would be more appropriate?
Thank you so much!.
Question from user Hrvoje Golcic at stackexchange
Answer:
I wouldn't go more than 1/2 the thickness of the "narrowest" pieces. Based on your drawings, that looks like ~1.5". Your wood is going to be strongest where it isn't cut, so you'll want to leave as much uncut as possible.
The strength (or weakness) will depend largely on the precision with which the joints are cut. What you want to achieve is the lap joint fitting together as cleanly as possible.
Any "slop" or gaps in the lap joint takes away from the overall strength of the "platform". It's the cross pieces fitting tightly into the joint that makes up for the fact that you cut some of the wood away from the other "beams".
Not using glue for these joints will greatly diminish the overall strength of the "platform" as well.
It's unclear how you intend to affix the platform to the legs, but some version of a lap joint should work well for that as well. Also, you might want to consider some kind of secondary bracing or crossmembers if the "legs" are not going to be fastened to the walls to prevent the structure from racking. Even small movement will distort the joints and weaken the structure.
Answer from user gnicko at stackexchange
I bought the glued dried pine wood already. I will use screws because I want to be able to disassemble it easily on demand. I also want to achieve that cross connections are aligned as a straight plane on the top, as shown on the image, so I have no gaps for the top board. That means I need to cut out the beams one into another to achieve it.
The question is, for the marked joint in the middle of the 2.5m (100") beam, what is the optimal depth that I can cut out the lap-joint on each of the beams in order not to weaken too much neither the top or the bottom beam. Should I cut into the middle of the top beam, or go even more, not to weaken the bottom 2.5 (100") beam which needs all the strength? On top will be a loft bed 160cm wide with not more than total 200-300kg of weight. Here are the two examples, which one would be more appropriate?
Thank you so much!.
Question from user Hrvoje Golcic at stackexchange
Answer:
I wouldn't go more than 1/2 the thickness of the "narrowest" pieces. Based on your drawings, that looks like ~1.5". Your wood is going to be strongest where it isn't cut, so you'll want to leave as much uncut as possible.
The strength (or weakness) will depend largely on the precision with which the joints are cut. What you want to achieve is the lap joint fitting together as cleanly as possible.
Any "slop" or gaps in the lap joint takes away from the overall strength of the "platform". It's the cross pieces fitting tightly into the joint that makes up for the fact that you cut some of the wood away from the other "beams".
Not using glue for these joints will greatly diminish the overall strength of the "platform" as well.
It's unclear how you intend to affix the platform to the legs, but some version of a lap joint should work well for that as well. Also, you might want to consider some kind of secondary bracing or crossmembers if the "legs" are not going to be fastened to the walls to prevent the structure from racking. Even small movement will distort the joints and weaken the structure.
Answer from user gnicko at stackexchange