RichardA Posted January 17, 2019 Report Share Posted January 17, 2019 5 hours ago, Isaac said: . If you get rid of all four shoulders, you lose the ability to control the depth of the installation. I'm not sure that's correct. The depth is controled by the depth of the mortise, regardless of shoulders. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted January 17, 2019 Report Share Posted January 17, 2019 There are a lot of statements being made here that are only true in certain designs. I think the question was asked in too open ended a way. Quote Link to comment Share on other sites More sharing options...
Isaac Posted January 17, 2019 Report Share Posted January 17, 2019 46 minutes ago, RichardA said: I'm not sure that's correct. The depth is controled by the depth of the mortise, regardless of shoulders. Well, the mortise depth certainly controls the max you can insert the tenon. Unless you push extra extra hard!!! But that approach requires precision in cutting your mortise depth, which is a little tricky, since it is concealed. Also, it is easy to accidentally install a tenon only 98% of the way in. With shoulders you have a clear visual cue telling you if the tenon is fully inserted or not. That is all I was really getting at. 2 Quote Link to comment Share on other sites More sharing options...
Isaac Posted January 17, 2019 Report Share Posted January 17, 2019 2 hours ago, Dmatt said: I am a complete noob to woodworking, amsd have found this thread very imformative. I have only built 1 bench with mortice and tenon joinery. I cut 5/8"thick 2 1/2" high by 2" long tenon on the ends of 1/2" by 3 1/2" strechers and 4by 5 corner posts. I read somewhere that a tenon should be 1/3 the thickness of the main beam and 3 times as long as thick. Is this normal porportions? Sounds reasonable. Keep in mind some joints are stressed much more than others. For example, the joints of wooden chair can be quite demanding. Others are low stress, and a wide variety of options will likely suffice, Quote Link to comment Share on other sites More sharing options...
RichardA Posted January 17, 2019 Report Share Posted January 17, 2019 1 hour ago, Isaac said: Well, the mortise depth certainly controls the max you can insert the tenon. Unless you push extra extra hard!!! But that approach requires precision in cutting your mortise depth, which is a little tricky, since it is concealed. Also, it is easy to accidentally install a tenon only 98% of the way in. With shoulders you have a clear visual cue telling you if the tenon is fully inserted or not. Cutting a mortise to depth is easy enough if you have a chisel and a depth gauge. Concealed or not.... With shoulders you have a clear visual clue that you've reached the shoulders, unless of course, you've used a chisel and a depth gauge to be accurate with your tenon. As far as pushing extra, extra hard, you're still only going to reach the bottom of the mortise. I seem to be having a problem with your arguement. I could very well be wrong. But I don't think so, especially after making as many mortise and tenon joints as I have hair in my beard. Quote Link to comment Share on other sites More sharing options...
Isaac Posted January 17, 2019 Report Share Posted January 17, 2019 7 hours ago, RichardA said: Cutting a mortise to depth is easy enough if you have a chisel and a depth gauge. Concealed or not.... With shoulders you have a clear visual clue that you've reached the shoulders, unless of course, you've used a chisel and a depth gauge to be accurate with your tenon. As far as pushing extra, extra hard, you're still only going to reach the bottom of the mortise. I seem to be having a problem with your arguement. I could very well be wrong. But I don't think so, especially after making as many mortise and tenon joints as I have hair in my beard. It’s a matter of degree. With your approach, you have to cut the mortise the exact depth you desire and you have to be certain no debris or excess glue gets to the bottom. If it does, that debris and glue will have no where to go when the tenon is inserted and your tenon might wind up inserted 1/16 or 1/32 less than desired. I think most would prefer the mortise be slightly deeper and use the shoulders to ensure the distance from face to face is the same on multiple pieces throughout the project. @wtnhighlander made the same case in another post on this same thread if you’d like to see another explanation. Quote Link to comment Share on other sites More sharing options...
gee-dub Posted January 17, 2019 Report Share Posted January 17, 2019 Good thread. Good discussion. I'll add that on tenons longer than some ratio that is subjective to me, I will scratch a groove in each face of the tenon to allow glue to move or 'escape' a certain area when plunging the tenon into the mortise. I guess I can also toss out there that I apply the glue to the mortise walls and not to the tenon. I know there are different school of thought on this but, I haven't lost one yet 2 Quote Link to comment Share on other sites More sharing options...
walidantar Posted January 17, 2019 Author Report Share Posted January 17, 2019 15 minutes ago, gee-dub said: I will scratch a groove in each face of the tenon to allow glue to move or 'escape' a certain area when plunging the tenon into the mortise. i want to ask you about the matter, what if adhesive is not used at all but a big bolt '1/2" lag screw' instead - for example the lumbers 4ft or 5ft long of actual size 2"x4" lumbers connecting the left leg with the right leg .. the same concept - no shoulders but the whole lumber inserted in the mortise that is 1" or 2" deep .. is it acceptable for a sturdy bench or it would wobble while working with hands i see the joint that should be glued are the woods that are within the same leg but not the every part of the bench Quote Link to comment Share on other sites More sharing options...
Chestnut Posted January 17, 2019 Report Share Posted January 17, 2019 14 hours ago, Dmatt said: I am a complete noob to woodworking, amsd have found this thread very imformative. I have only built 1 bench with mortice and tenon joinery. I cut 5/8"thick 2 1/2" high by 2" long tenon on the ends of 1/2" by 3 1/2" strechers and 4by 5 corner posts. I read somewhere that a tenon should be 1/3 the thickness of the main beam and 3 times as long as thick. Is this normal porportions? This is a common guideline but like any guideline it's just a starting point. I've made tenons that were the thickness of the material and just had shoulders on 2 sides. I don't generally go thinner than the 1/3 just because the tenons get thin at that point and the chance of them breaking increases. I try and keep all tenons thicker than 1/4". Generally thicker is better. The larger determining factor is the amount of material left on either side of the mortise. Quote Link to comment Share on other sites More sharing options...
Isaac Posted January 17, 2019 Report Share Posted January 17, 2019 17 minutes ago, walidantar said: i want to ask you about the matter, what if adhesive is not used at all but a big bolt '1/2" lag screw' instead - for example the lumbers 4ft or 5ft long of actual size 2"x4" lumbers connecting the left leg with the right leg .. the same concept - no shoulders but the whole lumber inserted in the mortise that is 1" or 2" deep .. is it acceptable for a sturdy bench or it would wobble while working with hands i see the joint that should be glued are the woods that are within the same leg but not the every part of the bench 1" tenon with a 1/2" lag screw hole will not be very strong, as you aren't leaving much material at the end of the tenon at all. 2" would be much better. Work benches tend to be subjected to a lot of thrusting forces, from things like pounding and planing. They are not just static shelves. Those thrusting forces make the bench want to distort into a parallelogram. Using a single metal bolt or screw presents a problem, because the only thing you have resisting that distortion is friction to stop it from rotating, like a pivot point. Wood expands and contracts with changes in temperature and humidity. This will result in varying degrees of tightness of your fasteners, and can even cause them to slowly work themselves loose. Using two or more bolts at each connection will reduce the rotation tendency. Still, a snug fit, with glue, would be a better, long term solution. Anyways, it feels like you keep asking the same question and everyone is telling you they don't recommend bolts. If you can make the mortise, why do you keep wanting to add bolts to the equation? If you really want this thing to be able to be broken down, there are additional options, but those methods generally require even more precision and skill in installation. Quote Link to comment Share on other sites More sharing options...
Coop Posted January 18, 2019 Report Share Posted January 18, 2019 Not to hj this, but the question has to do with the subject. Would most agree that the shoulders main purpose is: 1) to conceal any imperfections between the mortise and tenon and 2) to insure, if cut right, that the two joined pieces are square to each other? Quote Link to comment Share on other sites More sharing options...
RichardA Posted January 18, 2019 Report Share Posted January 18, 2019 It's not really the main purpose. though that is a side effect. and in most cases a welcome one. The main purpose of the shoulder is esthetic. It gives the eye a different line to see. The tenon if cut properly doesn't require a shoulder. But the shoulder does in fact cover any error in the chopping of the mortise. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted January 18, 2019 Report Share Posted January 18, 2019 I think it also lessens the need to have an exact mortise depth. Historically that would have been the most difficult task in small mortises. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted January 18, 2019 Report Share Posted January 18, 2019 I would say Ken's items are correct, but maybe reverse order of importance. Quote Link to comment Share on other sites More sharing options...
Brendon_t Posted January 19, 2019 Report Share Posted January 19, 2019 On 1/17/2019 at 5:28 PM, Tpt life said: I think it also lessens the need to have an exact mortise depth. Historically that would have been the most difficult task in small mortises. Agreed, plus the fear of hydrolock with adhesives. I'd rather have some extra depth in the mortise and seat against the shoulder. Quote Link to comment Share on other sites More sharing options...
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