Hot answers tagged

22

Hoping to run into some more tests and calculations but this is a good start. Yes Clamps can be too tight and the joint could weaken or even warp, in a sense, if too much pressure is applied. I found this out by accident using spring-style clamps to repair a break in a board. I left it out overnight for the glue to set with 3 spring clamps keeping it in ...


21

For clamping box joints, I've found that offsetting the clamps just to the inside of the fingers ensures you will be able to pull the corners tight. With the clamps there, you will still be pulling the joint closed while introducing relatively no bending to the boards. Picture below (source: RodsWoodworking.com). You could, as you suggested, make some jig ...


19

I tried clamping a square to inside of the joint, which works well for keeping the joint square, but doesn't seem to apply enough pressure to pull the fingers tightly together. I think that's basically the right idea but could do with being implemented differently: [Source: Wood Magazine] Another option that you might like to consider is something similar ...


17

I picture a jig of the same diameter as the circle so that it can't bow out but I wonder if there are simpler ideas. Likely this would apply as well to other things and not just circles... other polygons with a large number of sides. Lots of people use ratchet straps to clamp odd shapes together: (source) These are nice because they apply a consistent ...


11

Pipe clamps are very inexpensive compared to parallel bar clamps (also called K-body clamps), and have a virtually infinite range of clamping capacities because you can always replace your pipe with a longer or shorter one, or extend it with a pipe union and another pipe. With a parallel bar clamp, you're stuck with the length you originally purchased. You ...


10

Yes in this case it could be fixed easily. I disassembled the clamp and found one piece a steel with an obvious mechanical failure: This piece of steel is the one that prevents the clamp from opening, so it makes sense that over time it will bend in this direction. I bent it back to its original shape, and put everything back together; Nothing else was ...


10

I have used ratcheting band clamps on curved shapes with very good results. ( I could not find an image using the clamp on a circular form, but the principle is the same.) Rather than applying pressure in a single direction it provides uniform pressure towards the center.


10

If you're using most modern glues you do need clamps*, or some substitute, here. Hide glue is the one exception since it can be used to create rubbed joints. Although some people use PVA-type glues in this way in limited circumstances hide glue is the only adhesive that you can really do this with and achieve a proper result at a large scale (that result ...


9

You can extend the reach of pipe clamps by connecting two together with a coupling. That requires that those ends be threaded.. Most people cant thread them at home, so it's better to get them threaded at the store up front so you don't have to make two trips :-)


8

My question is, why use so many F-style clamps rather than just 3-4 parallel bar clamps that would cover the entire surface? Probably the simplest explanation is to spread the clamping force more uniformly. Although this can be done using fewer larger clamps too, with use of clamping blocks, which appear to be in the photograph anyway. Side note: I glued ...


7

The long board clamped across the piece is a valid plan. But to get the downward force where you need it you'll need to put something between the board and the clamp area. A simple candidate is a block of wood and a wedge to fine tune the clamping force. You can replace the wedge with a screw that will push against the block. Note that the board will ...


7

Yes clamps can be too tight but not for the reasons stated above. TL;DR The fear is that over-clamping will lead to a starved joint is largely baseless. In practice it is nearly impossible to do without severely damaging the wood. Necessary clamp pressure has been studied extensively by scientists for the timber industry, who, unlike woodworkers, can't ...


6

Although the threaded ends can be used to extend the pipe to a longer length, the threads are used to hold a part that comes with the pony clamps. It is a piece of coiled wire that fits the threads so the sliding potion of the clamp does not come completely off the end.


6

your idea of adding a rib to keep the heads in line has merit and will do what you are wanting. However, my pipe clamps are similar in that the movable part can rotate all the way around the pipe. Generally once you start tightening things down they don't twist and are not a problem. On top of that as TX Turner pointed out, sometimes not having them ...


6

Some sort of caul. You can make one to apply pressure at a single point, or have a slight curve to apply pressure more evenly across a panel.


6

It sounds like you're running your bit too slowly. Spade bits are pretty sensitive to low speeds. A faster speed (and less feed pressure) will result in less material being removed with each pass. This, in turn leads to less force on the wood, resulting in less tearing of the fibers. This tearing of the fibers, instead of cleanly cutting them, is what ...


5

In addition to being much cheaper than bar clamps, pipe clamps allow for much higher clamping pressure. According to this article in Fine Woodworking, a typical parallel clamp can reach about 370 pounds of pressure. 3/4" pipe clamps can reach 1,050 pounds and the I beam style bar clamps can reach 1,350 pounds. One of the downsides to pipe clamps was that ...


5

Another name for cam-style clamps is eccentric clamp, named after the eccentric circle principal that it uses -- the rod goes through the black plastic cams closer to one end than the other, so when you rotate the rod, the portion of the cam between the rod and the clamped surface increases, providing clamping power. But, searching for that doesn't get me ...


4

I would invest in some of thise: Collins Miter Clamps I bought a set a little over a year ago, and I'll never do miters without them. They are especially great for trim work.


4

There are a variety of options out there similar to what you are describing. These are the first two that come to mind: Rockler Hold Down Clamp Bessey Hold Down


4

I find these clamps to be reasonably unreliable - in my experience they all eventually fail as you describe. One of the causes is that the bar becomes too smooth for the clamp to get sufficient friction. In this case you can try filing/roughing up the bar at the front and back to give it something better to grip on to.


4

Nah, I wouldn't bother trying to stop the twist. You can turn the face 180 degrees and use it like an expanding clamp, or a jack. There's a lot of neat things you can do with two jaws that don't have to be parallel. :)


4

It's certainly possible to damage squares and/or levels by clamping. So if you're looking for a yes or no answer, it would have to be yes. However I can think of plenty of situations where I would clamp either of these and do so in a way that does not degrade their accuracy. I would say the risks are these: Clamping directly (without a pad of some sort) ...


3

If the clamp is sitting on a flat surface, it won't twist when you're tightening it down. (And then if it is tight, it won't twist either.) But to answer your question, you could run 1/4" threaded rod, nutted firmly to the front and the back, and through a free-running hole in the moveable part of the clamp. That won't totally control twist, but I think it'...


3

The 2 things I can think of that help. rotating which face is 'up' strip by strip. for things as thin as what you are dealing with what will make more difference is alternating your pipe clamps between 'top/front' and 'bottom/rear'It is a little more difficult set up, but if you have pipe clamps you can lay out on a table put your glued up pieces on them, ...


3

Strong magnets... For example if the board is thin and you have access to a magnetic drill you can place a piece of steel plate behind the wood board and the magnetic drill will pull against that during drilling operations.


3

You can always make long-throat clamps, like these ones by Matthias Wandel: Making long reach C clamps on YouTube


3

Ratchet straps go around things and hold them together, so yes. Obviously, you don't want to damage your piece, so take whatever steps are necessary to prevent that (e.g. cardboard or cloth pads at contact points, etc.). See also strap clamps, which usually come with some nice little corner things to help distribute the load. If you try it once you'll get ...


3

This is not generally done, although I'm sure I have seen the vice being used for glueing up certain jobs, mostly between the jaws, I can't remember the sources. One passing reference to this the poster said he'd never do it again though, since the glue dripped onto the vice screw and guide rods and made a mess that was tough to clean up. Too much strain ...


3

You are not dealing with warped wood here. Your last picture shows that you have a moisture problem (due to a change in the ambient moisture content of the air - change from a dry climate to a wet climate, moved outdoors from a controlled environment) that has caused the bottom to expand and in the process push the the front legs forward, breaking the end ...


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