![]() ![]() I have a couple of friends that swear by domino’s and beadlock. Within a day, I was cutting professional quality mortise and tenons. Learning to use the two was not as bad as I thought. These two have become indispensible and have since paid for themselves. sets of hollow chisels and bits plus a riser block. I think I paid $150 for the pair and the mortiser came with 2 4pc. About a year ago, I stumbled on a dedicated mortising macine and tenon sled both on clearance to make room for new models. ![]() Sometimes with good results, sometimes frustrating failures. Incidentally the half lap ( in part 2) failed at 1918 lbs !! The mortise and Tenon took 2 tons of force before failure in the “pull apart” test!! The videos really give a good indication of how the wood will fail in before the glue joint in each application. You can see as it fails it is the additional glue surface that the biscuit provides that is enhancing the strength of the glue joint. The miter with the biscuit failed at 220 lbs of force. In the first video at 4:32 the unreinforced miter failed, in the shear test, at 139 lbs of force. Wood magazine has two videos entitled “Wood Joint Torture Test”. The buscuit as Mark said provides the joint with more glue surface which will naturally enhance the strength of the joint. Titebond 2 has a spec of 3750 psi with wood failure rating of 72% per Titebonds website. In regards to strength this might resolve a bit of the speculation. Oddly enough, as I wrote this, I noticed Tom Iovino from Tom’s Workbench put up a similary-themed blog post in the community. If I were you, I would definitely opt for tongue and groove or mortise and tenon joints. But if the biscuits were used for end-grain joinery, I wouldn’t recommend moving that chest around too much. If the maker of that oak chest used biscuits in a bunch of long-grain joints, it would probably be a reasonably sturdy piece. But I do suppose for light-duty pieces, they would be acceptable. So in case you couldn’t already tell, I would never use biscuits as a primary form of joinery, especially when there are end-grain to long-grain joints involved. Make no mistake about it: the biscuit joint is no substitute for the mortise and tenon, or its little brother, Prince Tongue and Groove! All three of the biscuits weaknesses listed above are the reasons for this. ![]() As a result, the joint has a great deal of glue surface and strength. The real magic of the mortise and tenon joint is that it takes this end grain to long-grain union and converts it to long-grain to long-grain, simply by inserting one piece into the other. Traditionally, this is the territory of the King of Woodworking Joints: the mortise and tenon. So we absolutely need some form of reinforcement. Whenever end-grain is involved, the joint will be inherently weak using glue alone. Think of a rail meeting a stile or an apron joining a table leg. Now the second situation is end-grain to long-grain. But if they help you align the boards, I see no harm in using them. So adding a series of shallow biscuits isn’t really going to make the joint much stronger. As you have heard me and others say many times, the glue joint is stronger than the wood itself. In this long-grain situation, its really the glue that’s doing all the work. Some folks (including me) may use biscuits for alignment or “reinforcement”, but the truth is they do very little to strengthen the joint. Lets look at the two most common areas where you could use a biscuit, with respect to the grain direction of the adjoining pieces.įirst, there’s long-grain to long-grain (a tabletop glueup is a good example of this). But in most cases where biscuits are being used, its the glue that’s doing all the holding. And I honestly don’t think they are a bad option for light-duty pieces either. Ideally, the grain would run perpendicular to the joint.ĭespite their shortcomings, biscuits are still very handy for alignment, especially when doing big tabletop glueups. – The grain of the biscuits runs on a 45 degree angle. – The biscuit doesn’t penetrate very far into the joining workpieces: a #20 biscuit will penetrate less than 1/2″. – Biscuits slots can be a little tight or a little loose, depending on your machine and how steady your hand is. Biscuits don’t really have much to offer in the way of strength. Am I wrong? If I wanted to join two boards together, would a tongue and groove be more solid in the long run? What do you think? Anyway, I saw a video on youtube of this very nice oak chest, but the craftsman used mostly biscuits to join almost everything, I wouldn’t think that biscuits would be strong enough to last a lifetime. I don’t have many tools, and the ones I do have are Ryobi (fairly cheap) but I like them.
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