this is the problem with threaded inserts

this is a metal threaded insert and today I will be testing it head to head against wood tab threads for strength and durability which one will come out on top the results will surprise you look not every Furniture can be glued permanently into a giant piece that cannot fit in cars or through doors so I completely understand the need to use threaded inserts to be able to take something apart for transportation purpose if you're like me you might say metal is stronger than wood right so threaded inserts make a lot of sense if you want strength some people also believe metal threads can be used over and over again without wearing it out but are any of these two things actually true we are about to find out okay so let's talk about our testing setup all of these tests will be done using cherry Lumber because it is a nice middle of the ground hardwood we're also using quarter 20 threads because to be quite honest with you I've spent a lot of money on testing equipment for this video as is and I'm not about to go buy more crazy industrial equipment to capture those High forces so we'll be using this extremely popular style of threaded inserts that come with the recommended pilot hole size of 25th 64th of an inch because you know we all have one of those bits around in the shop for the wood tap threads I will be using this bottoming metal tap I got from Amazon for five dollars this bit has less taper at the tip when compared to Conventional metal tap and as a result it cuts the threads nearly all the way through at the bottom and because we're tapping threads into wood we don't really have to follow recommended metal pilot hole sizes I'm using a smaller 1364 of a bit that should give us some nice perfectly cut snug threads one of the main advantages of using wood tap threads is how easy it is to make them you simply drill a hole and then drive the wood tap with a drill done deal on the other hand metal inserts are a pain to install in the case of this insert we need to drill a 25th 64 of an inch of a hole and then countersink that hole to accept the flanged part of the insert we then drive the insert into the wood using an allen key or one of these t-shaped thing about no matter the tool I usually have a hard time keeping things Plumb as I insert the piece which can result in a wonky fit because I know you guys will ask in addition to keeping the metal inserts as is I will be adding another test using super glue to lock the threaded inserts to see if it helps strengthen anything in the same way I will be using super glue to harden the wood tap threads so in total there are four sample pieces threaded insert threaded insert plus Super Glue wood tab threads and wood tab threads plus super glue the first test is going to be an endurance test according to the United States Census Data an average American moves 11.7 times in their lifetime for the metric folks an average Brit moves eight times in their lifetime thought that was interesting since threaded inserts are used for knockdown January for moving I'm going to simulate that by assembling and disassembling a bolt not just 12 times but a hundred times so here I have our four types of test pieces I'm going to insert a quarter 20 bolt 0.6 inches deep in all instances because that is the length of our metal threaded insert and we want to make things a little bit comparable between tests using a dial indicator I am first measuring the amount of run out before the testing begins so we can compare it after the test while I expected the initial run out to be the same in both metal threaded inserts that was not really the case here interestingly the wood type threads had an initial run out of .019 inches and this super glue threaded insert barely had any run out at .001 inches using a hand drill at a clutch setting of number five which felt pretty sufficient for how much torque I would normally apply to a bolt I am going to insert and remove the bolt a hundred times on each of the four samples and right away we've got a problem the wood tab threads in both instances made it to 100 though they did take a little bit of a beating unfortunately neither of the metal inserts made it that far the outer threads that meet the wood gave up in both instances where the inserts would spin freely and I could not move forward with the test the bare threaded inserts got to 38 attempts while this super glue insert made it to 30 attempts I don't think the small difference between the 38 and the 30 is Meaningful but it is important to know that they both failed so early in the testing okay now measuring the post test run out the insert had a pre-test run out of .033 inches while the pose test run out came out to .055 inches for the super glue threaded insert we had a pre-test run out of .022 inches and a post-test run out of 0.027 inches most of the metal insert run out is from failure between the wood and the outer threats and because of that the super glue helped the second test perform a little bit better for the wood tab threads the bare sample had a pre-test run out of 0.019 inches and a post-test run out of 0.041 inches the tap threads with super glue had a pre-test run out of .001 inches and a post-test run out of .029 inches comparing the results side by side you can see both wood tab threads and metal inserts perform similarly when most people would have expected the wood tap threads to fail in this test if anything the metal inserts failed because we couldn't really make it to the 100 tries and the wood tab threads look like it can still go back for some more on the next test I'm going to strip the threads by over torquing them oh and I've upgraded the bolts to stainless steel because the basic Bolts from the Home Center didn't hold up here I have the same Force set up as before in order to measure the torque I will be using using this digital torque wrench and set it to Peak measurement using a double nut locked bolt set at .06 inches depth I'm going to continue to spin it until the threads give up starting with the bare metal inserts it took 37 inch pounds of torque and the failure was not actually the metal threads instead between the outer threads and the wood I did another four samples and removed the lowest and highest value and got an average of 37 inch pounds for the bare threaded inserts the threaded inserts with super glue took an average of 36 inch pounds with the same type of failure as before the bare wood tap threads took an average of 52.7 inch pounds and the wood tab threads with super glue took an average of 66.3 inch pounds looking at the summary you can see the wood tap threads take a lot more torque to fail when compared to metal inserts and the use of super glue in Wood tap threads definitely help add a little bit of strength the metal inserts take far less torque to fail in both cases and gave up between the outer thread and the wood our third and final test is the most fun in this test I will yank the bolt straight up and try to strip the threads in the process this is our setup at the bottom we have our piece of wood with a bolt 0.6 inches threaded into the test piece the bolt is attached to a crane scale that will tell us how much we are pulling on the bolt the scale is attached to a chain hoist for pulling because I've got weak arms starting with the bare threaded insert the first sample took 252 pounds of force to pull it out I did another four samples and again removed the lowest and the highest value for an average of 234 pounds of force all of these five samples failed between the threaded insert and the wood using the threaded insert locked with CA glue it took an average of 285.7 pounds of pulling force moving forward to the bare wood tap threads it took an average of 494.3 pounds of force it is really fascinating to see how the wood fails all at once and shatters the wood fibers along the grain examining a little closer you can see the actual threads appear to be in perfectly good shape while the rest of the woods surrounding it is what fails now for the final piece where the wood tap threads have been stabilized by using super glue it was a little tight and I had to use a wrench to get all the way seated these samples took an average of 472 pounds to pull out looking at the summary the yanking test results show a clear strength among wood type threads when compared with metal threaded inserts let's be frank here quarter 20 threads are tiny and in most woodworking projects you can use much bigger and deeper threads on even harder Woods that'll give you substantially more holding power I'm not here to convince you to use wood tap threads I just want you to note that wood tab threads are a lot stronger and better than you might have originally thought if you have any interesting woodworking testing ideas let me know in the comments down below until then I'll see you on the next one

Channel: WoodcraftBySuman

Views: 399,047

Keywords: threaded inserts, threaded inserts for wood, woodworking tips, woodworking tools

Id: S4SnrbGwGpI

Length: 9min 41sec (581 seconds)

Published: Fri Dec 16 2022