. . . it can stymie your work!
There are so many things woodworking that are taken for granted and my posting the picture below on my Facebook with a short, almost invented conversation sparked off almost 3.7 million views in just four days with 2,000 comments and 440 shares too. The preconceptions people had and put forward by way of comments showed real prejudices people had that were most of them unfounded but some that should be considered but mainly not as serious as they thought or indeed were taught.
Many things did come out of the woodwork in the last four days or so, not the least of which was the limited and distorted views people have about certain things. Peer reviews can be very interesting and occasionally helpful as in our tunnel vision we can miss things that others see but the worst thing beyond being occasionally helpful is the level of true honesty when jealousness or envy raises an ugly head.
Here are some thoughts from my posting the single picture on my FB page four days ago. I will post them as questions rather than the vague and obscure statements they actually were. I think it is interesting to see people’s perspectives. here is the offending image:
Q: If you drive a steel screw into oak, or any other wood high in tannins, the acidity causes the screw to rust. True or false?
A: True: This can and does often happen but mostly if or when the oak is exposed to high levels of moisture in the wood and surrounding the screw be that from water as liquid, steam or local humidity in areas with high humidity. This can be in regions of countries, in homes and businesses and then in rain and so on.
Q: Should you never use steel screws in oak then?
A: You can use steel screws in oak just fine, craftsmen have done so forever, but you should consider where the piece you are making will stand in its final positioning. There are thousands upon thousands of oak doors here in the UK ranging from small entryway doors to massive 20-foot high entrances to colleges, universities, public buildings and offices six-foot wide hanging from steel hinges with every type of steel fastenings ranging from strap hinges, hasps and such held in place with steel bolts and lag bolts passing into and through the oak. They have been there for decades and even centuries. If it is an indoor cabinet or dining table, something like that, there should be no problem but bathrooms with steamy showers might be more questionable.
Comment FB Statement: If you drive steel screws into oak it will cause rust and the rust will split the oak
Q: Can rust cause wood like oak to split?
A: Not directly, no. And of course, rust will never cause oak to split. What can happen though is if the area around the screw is exposed to long-term moisture it can cause rust in the screw and this can adversely impact the wood causing some breakdown in the fibres directly around the screw. In any case, rust does not cause oak to split and neither will it any other wood. Poor workmanship, not drying the wood down to acceptable levels as in drying before use can allow wood to shrink further and the resistance of the screw can prevent tolerable movement in the wood resulting in a split. That’s why, in joinery, we generally get the moisture levels down to acceptable levels before we start the joinery. Expansion in joinery very very rarely causes an issue but shrinkage can and often does.
In dry conditions, and if the wood was indeed fully dried before the screws were imported to the wood, this is most unlikely to happen at all. In our historical past, wood was limited to air-dried levels usually under a cover or in a barn which still left high levels of residual moisture within the fibres of the wood. The general rule was to make it and watch it before selling to make sure once it was made no cracks arrived before it was sold. In good workshops, and we are talking from the 1600s on to the invention of properly controlled kilns, wood would be taken from the barns and under covers into a tighter and more controlled environment where heat in the general atmosphere was lowered by fires and heating. It wasn’t the equivalent of a kiln but better than from the barn. In vernacular furniture, wood was worked because they couldn’t get the moisture down any further. Today, our oak is dried down and can indeed be drawn down further through kiln drying and centrally heated climate control in buildings. `we do not face the same issues. Generally, oak is dried down to between 7-12% and this will pose no problems for us long term.
Screwing into end grain also figured high on the list, but mostly people made assumptions and statements instead of simply asking transparent questions.
Q: I see the screw goes into the end grain and I was always told never to do that because the screw has no holding power.
A: I think we all know that screwing woodscrews into end grain generally has less pull and retentive power but it’s not nor is it near no pulling power or retentive value. Experience has clearly proven to me that every wood is different with regards to ‘hold‘. It has also told me that screwing into end grain works well most of the time. Some woods do take a thread really well and give a thoroughly good bite whereas others can be pretty crumbly. In 99% of cases, end-grain screw hold will pull and hold just fine. It’s been done for at least a century and a half to date and it will continue to be done, otherwise, everyone needs to ditch their pocket-hole joinery which is not actually joinery.
With the development of the battery-driven drill-driver came excessive power many times greater than hand power to drive screws. At woodworking shows these days you’ll find a two-by-four with a hundred screws driven into it for customers to check out the latest Dewalt impact driver. Mostly it’s the macho-man thing, muscle flexing to try to stop the drill mid-drive then standing back in admiration. That’s not us. Drive with too much torque and there is no doubt that the wood will give in the end-grain part of the connection. On the other hand, we might find it impossible to drive the same 3″ screw with a hand screwdriver.
Unfortunately, we live in an age where the screw is developed to self-drill and countersink with supposedly no need to predrill and use pilot holes. On a deck or in stud walls in soft-grained, mushy wood this works well. It’s still crude but it is functional and fast and that’s what makes the money. I think that there was something of an assumption in the commenters on my FB post that I did this with the screw through the dovetail and then into the end grain. Had I indeed done that then I am sure it would have split and stripped out. And this is the fallacy in it all; they assumed I was just like them. The drawing below will show the strategy I always use. It’s one that never fails.
Of course, nothing reads never screw into end grain, as many said. It just means your reliance should be, well, slightly adjusted. In the case of the image, people made too many assumptions and I understand because I did lead it in that direction. I wondered how they would perceive such a concept, a perfectly made hand-cut dovetail with a screw driven through it to pull it together, and they proved many wrong theories have indeed taken deep root. They declared that the wood would split, cause weaknesses, take out too much wood and thereby make the joint substantially weaker, that the screw itself would split the wood and another half dozen issues that quite frankly were indeed inconsequential. In reality, not one of the concerns offered, and there were a couple of hundred, were true in much of anyway. That said, something somewhere had indeed informed them. By informed I mean formed-in or in-formed. Somehow the tannic acid in the wood was going to cause the screw to corrode at some alarming rate. Whereas tannic acid in oak is something of an issue, it’s only truly an issue where neglect and high levels of water surround the steel and the wood. Would I have used steel woodscrews in an oak project exposed to high levels of humidity? And by that I mean green oak or oak to be used outdoors. No, I wouldn’t. But then, as said, thinking of the hundreds, no, thousands of doors made from solid oak where the hinges are indeed bolted and screwed with steel fastenings to oak, I personally think it’s fine. Somehow we have gone overboard on the issue to the point that you should NEVER use steel screws in oak. That is what happens when we become offended. It leads mostly to unjust criticism often resulting in impractical silliness and of course, legalism; legalism has a way of hanging us up. Several offered the solution to be to use stainless steel screws. Though it is true, and we could do better by using stainless steel, I thought that was funny. It was the assumption that we have stainless steel screws of the exact type with the right head, screw thread length and diameter hanging around in boxes and that they would be available right there in the zone. That was just too much for me. I confess, I did laugh at that; quite a lot.
Now, that the screws will split the oak, split the dovetail, rust in the countersink and so on. We take steps to prevent such things. The first one is to use a pilot hole so that the screw hole is stepped down in size. The hole in the dovetail takes the full diameter of the screw and then countersunk at the same angle as the underside of the screw head. This seats the screw nicely. In the second, lower piece of wood receives the pilot hole that does more than just pilot the screw but receives the main body of the screw minus the threads so that the threads alone bite into the walls of the hole. really gives good grip and pulling power and the wood does not split. Also, the tight dovetail, the size of the screw diameter, etc disallows the remote possibility of the dovetail splitting.
Ugliness was cited. Well, that’s all in the eye of the beholder. The accepted phrase in all design is that “form follows function” is as good a precept to accept as any I know of as a designer-maker. Everyone assumed that the dovetail would be seen and clearly visible when the job was done and no one of the earlier commenters asked if it would indeed be visible. It won’t, but there are times when it could be and it would offer a practical solution that dovetails only really have unidirectional pull in resistance. Adding the screw adds omnidirectional resistance albeit perhaps less so than the dovetail itself.
The screw itself in its beginning was the product of a highly inventive mind and goes back to around 400 BC to Archytas of Tarentum (428 BC – 350 BC). In our world screws and screw threads have become highly sophisticated to cope with the demands of fast assembly and production in different industries. In our woodworking world, the diverse designs cater to deck screwing complex fasteners. We buy them by the boxful in every type of metal available for different applications and environments. Think of where we would be today if we had stopped back in 400 BC.
In practical terms, it often eliminates the need for any clamping beyond the simple pull of the screw itself. In adding cleats to the insides of cabinets for shelves and drawer runners where clamping might be impossible the screw and glue conclude the work. Screws can, of course, be temporary and removed once the glue cures or they can be temporary until the glue has cured and then just left in place with no particular detriment even long term. In my situation at the top, there really is no truly good reason to remove it. Additionally, I might offer that the screw gave a fully centralised pulling dynamic smack on where it was needed slap bang in the middle of the dovetail joint. No clamps in the way for hours and no waiting for me to be able to continue in my working on the project. I have done this in hidden dovetails for half a century and I was taught it and trained to do it by men almost old enough to live in a time when wood screws with international availability were still on their way. It’s not a ‘Paul-Sellers concept’! It’s been done ever since woodscrews were invented.
I was surprised by the number of opinions people had. I might say ‘mere’ opinions for they were little more than that and with no substantive support or evidence. Many if not most were literally based on what I see as completely erroneous assumptions with no validity in the concerns expressed and yet the commenters were so adamant that what they thought would happen would indeed happen and destroy my efforts. It’s really unfortunate that the quantity of them was so many; too many for a lone man to counter because they came in so fast. Worse still really was how endemic these biases were, and I think that that was very unfortunate. So many put faith in just about any kind of dowel as a viable alternative to the screw while others said that removing material for the screw was weakening the joint itself. They almost all of them were so blinded by what was mere opinion rather than fact that they really were unwilling to adopt any other perspective than their own. I realise that mostly the contributors were inexperienced but it soon became apparent that it was as if their brains had been, well, copied and pasted. Replacing wood with wood via a dowel offers zero pulling power but they didn’t see or understand that. What I needed was the initial pull to keep the dovetail in the recess so I could keep working on the project. They dismissed this altogether which really surprised me. The thing that struck me was what I saw as high levels of self-righteousness for what was honestly presented and then too how many wanted me to then “at least hide the screw behind a dowel.“, thinking that dishonesty to be the more honest way and, yes, the better thing.
I did what I did to show the brutalism of legalism and control. I and thousands beside me have done this for generations. All of the men in my apprenticeship days did it because they needed to continue working on the pieces and they couldn’t wait for the animal hide glue to harden up for hours. I cannot tell you how many dovetail joints I have come across since my apprenticeship days (58 years to date) that were nailed after the glue was applied and the tails set into the recess but it is many a hundred.
For clarity to the first post, I added this text to a second, follow-up post:
For those with a genuinely inquiring mind seeking true answers but following certain erroneous precepts, there are many things to consider from my last post. So I did something probably or possibly none of you did and that is take two pieces I knew the age of and withdrew the steel woodscrews.
The drop leaf table is 85 years old. All of the screws holding oak to oak and steel hinges to oak are done using steel screws. I removed the screws and only one of the two screws had a very mild powdery dusting of rust. This would have happened in any wood. Certainly, nothing that will change in the next 200 years. The other table, again oak, was made 13 years ago with steel screws into the oak to hold the turnbuttons. There is no sign of rust anywhere. According to the expert comments on the last post I should be experiencing severe degrade leading to black staining, splitting of the wood and fragmented fibres. Had I and the other maker listened to these people we might have been put off. I own dozens of handmade oak pieces and not one of them shows the slightest signs of rust.
I encourage you all to question the authority of those who informed you. Yes, I can produce pieces where tannic acid has caused the rust on screws and the resulting black staining on the oak, but in every one of these cases, water had always been evident and excessive.
The result of my post was highly successful I think, and I thank all of the genuine enquirers for their input.
Oh, I added the cabinet I am working on so you can indeed see the context. The tabletop will be added next, then the drawer and the door.