Those Dreaded Catches

Richard Findley explores common catches, why they happen and how to avoid them

Catches are the bane of a woodturner’s life. All can be going well and, seemingly without reason and usually without warning, bang. Your work has an unsightly scar in it, which will call for minor adjustments at best and a major design change, or even scrapping the work entirely at worst.

In this new series I intend to explore these catches, looking at why they happen and how to avoid them, beginning with the most common catches that occur in spindle work. I will use the three main spindle turning tools – the spindle roughing gouge, the spindle gouge and the skew chisel – and hopefully will be able to shed some light on the issues that are commonly encountered. Often, as with most things in turning, a little knowledge and some tiny adjustments to how the tool is presented to the work is all that is needed to avoid these frustrating catches.

The spindle roughing gouge is one of the first to be used in spindle turning. It is largely a simple tool, both in design and the way it is used. For roughing or smoothing cuts in a straight line there is virtually no chance of a catch. In my experience the time to be aware of a catch is when adding more depth into the shaping of a spindle. As the cut progresses and the shape of the work becomes steeper, the tool can become more difficult to control. The reason for a catch is usually that the wrong part of the edge comes into contact with the work, which can aggressively grab the tool and pull it back up the slope that is being cut. The larger the diameter of the work, the more chance there is of this happening, as the forces involved increase with the diameter of the work.

The key to success is to keep the flute pointing in the direction of travel and keep the cut over the part of the tool that is in contact with the rest. In the photo below I am cutting downhill from left to right, so the flute is tilted to the right, but if the left side of the tool contacts with the work, or the cut moves too far to the left of the cutting edge, the tool will be pulled back uphill and to the left. Depending on how aggressively you are cutting, there can be warning signs that a catch is imminent. Usually, at the first sign of the tool fighting me I take it as notice to switch to a different tool, generally either a spindle gouge or skew, to finish refining the curve. That said, I know of production turners who do far more shaping with a roughing gouge than I do, while keeping perfect control of the tool.

Basic Catch Avoidance

Some simple steps can be taken to reduce the chances of catches:

• Ensure the tool is on the toolrest before touching the wood – This is the most basic of catches, but is still easy to let happen, often through a lapse in concentration. There’s nothing like the bang of a tool to toolrest to remind you that full attention is required at all times.

• Sharp tools – I have said this before and I will no doubt say it again, but sharp tools are the cure for the vast majority of turning-related issues. A sharp tool will cleanly and smoothly slice the fibres of the wood, whereas a blunt tool will be harder to control and be less predictable.

• Toolrest position – This is less critical the more experienced you become at the lathe, but the forces involved in turning increase as the tool overhang increases over the rest, in turn increasing the risk of a loss of control and so a catch. Keeping the toolrest close to the work will maximise tool control.

Skew chisel

The skew is something of a ‘love it or hate it’ kind of tool. It is possible to get through life without using one, but if you watch the best production turners they all use a skew of one type or another, whether it be a traditional rectangular skew, a round skew more a square one. The reason those who hate it do so with such a passion is because it is an unforgiving tool that dramatically punishes inattentiveness with a large, ugly catch.

The two main operations a skew is used for (there are others which I shall look at next month) are planing and bead rolling. In both cases, catches can largely be avoided by paying close attention to where on the edge the cut is coming from.

Planning

Planing is the most basic of operations with the skew. The main thing to understand is that, because the tool is presented at an angle with only its lowest corner in contact with the toolrest, the weight of the cut needs to be over this part of the tool, which is supported by the toolrest.

If you try to cut higher up on the edge, a part that isn’t directly supported by the rest, the reward is the tool being twisted down, slammed against the rest and a catch mark with varying degrees of severity on the work. The easiest way to ensure only the correct part of the edge is cutting is to use a marker pen to mark the ‘sweet spot’ or ‘safe zone’ on the edge. Ideally the cut should come from the lower quarter of the edge and not much higher than the centre of the blade, so a dot on this quarter point and a central line easily shows where the cut should be made.

Once this is understood, it is just a case of manipulating the tool and adjusting the presentation to ensure the cut is always coming from this part of the edge. For planing the point isn’t used, although if it does cut it won’t result in a catch, just a less clean surface finish. Some people say a wider tool is better to use because the ‘safe zone’ is larger. Others will tell you a narrower chisel is better as it doesn’t pull down as much of your cut high on the edge. The fact is they are both right and each turner must decide for themselves which style of skew best suits them.

Planning with the skew

Adjusting the height of the toolrest can help if you have issues with planing. Again, with experience the need for this reduces, but by raising the toolrest above the usual centre height, it can help to keep the higher ‘no go’ part of the tool’s edge away from the spinning work and give a much clearer view of what is going on at the cutting edge of the tool.

Bead rolling with the skew

This is possibly one of the most likely places that a catch can occur. Despite the difficulty and the associated frustrations in this action, the solution is actually quite simple. Once again, it all relates to the part of the edge that is used in the cut. Unlike planing, which uses the edge rather than the point, use of the point is the key to success.

If the cut is on the point of the tool it forms a small v-shaped groove and raises a feathered edge just in front of the cut. As long as you can see this throughout the cut, you can be certain that the cut is on the point and so in control. It is important to keep the tool rolling around the curve of the bead and moving forwards at all times. Hesitation and back-tracking are generally a recipe for a catch, so smooth, progressive cuts and movements are key.

Cutting on the point of the tool when rolling a bead gives complete control of the tool throughout the cut. A more advanced version of rolling a bead begins with a planing cut but will always end by cutting on the point. Which of the two points to choose is less important, but the long point gives far more visual feedback. It is very easy to lose sight of the short point as the cut progresses so, by using the long point, you can see exactly what is going on at the sharp end of the action.

Spindle gouge

A spindle gouge is generally more popular than a skew simply because it is much more forgiving. Catches are still perfectly possible, but they are usually less dramatic and less damaging to the work. The pattern emerging here is that the part of the tool’s edge that is used is vital to the success or failure of each different cut and the spindle gouge is no different. The most common catch with a spindle gouge I find is during the entry into a cove. If the presentation of the tool is just slightly off, the tool will skid to one side or the other.

For spindle turning with a spindle gouge, all the action happens right on the tip of the tool. If you are cutting to the left, the shaving should come from just to the left of the tip. When cutting to the right, the shaving comes from just to the right of the tip. The wings on a fingernail grind gouge are shaped like this to keep them out of the way and for shearing cuts on faceplate work, but are otherwise not used for spindle turning.

The reason the gouge skids off to one side as it enters the wood is that, at the point of contact, the edge needs to be vertical. If it leans to one side or the other it will pull the tool in that direction. To adjust this angle at the point of contact is simply a case of rolling the tool in the opposite direction to the way it is pulling. The best way to practice is to cut a series of grooves in waste wood with the tip of the tool, adjusting the presentation of the tool each time until the correct position is found.

My other recommendation for success with this cut is to make sure a slicing action is used, rather than jabbing at the wood with the tool. If the cut begins with the handle low and it rises in an arc as the tip enters the wood, the result is a clean slicing action and the success rate of this cut will increase dramatically.

Make friends with your tools

When you consider that every tool manufacturer produces tools with slightly different flute shapes, and every turner will grind their bevel angles and nose profile slightly differently, it becomes clear that my tools with my preferred grind are likely to react and feel slightly differently to another turner’s tools from a different manufacturer and ground to their preferred grind. I recommend getting to know how your tool cuts best and if you can’t get it to do what you want, regrind it until it will. Hands-on nights at a local club are a great chance to try out other turner’s tools and profiles and compare their efficiency.

Further into the cove

As a cove cut progresses, a catch is possible if the wing of the tool touches the far side of the cove. This is particularly likely on deep and narrow coves as there is less room to manoeuvre. I have found that, as well as vigilance to ensure the tool is still cutting near the tip as it should be, the grind I use on the wings of my gouge can be beneficial. By rolling the tool beyond 90° as I sharpen it on the grinder, it brings the cutting edge to a more closed position, which I find still allows it to shear cut on faceplate work when I need it, but means the wing is less exposed so less likely to catch accidentally.

Bread rolling with a gouge

There are two ways a gouge can catch when rolling a bead. Despite my best efforts I struggled to make either happen when I was shooting the pictures for this article and only finally managed it by combining the two faults I describe here. As before, as long as the shaving is being made close to the tip of the tool, then the tool should be perfectly controllable. The problems occur when the cut moves to the higher part of the edge which is unsupported, which can cause the tool to grab, twist and catch. I found that with my preferred grind I couldn’t get a catch, but different makes of tool and grind profiles are likely to produce different results.

The second issue with bead rolling occurs when the tool handle swings too much, lifting the bevel from the work and making the tool want to run back up the bead. Again, I struggled to force this to happen, but have experienced it on tall beads with quite straight sides. This issue will be revisited next month when I look at end grain slicing on spindle work.

Top tip

Practice spindle turning. So much successful turning relates to practice and I would recommend starting with softer timbers such as pine or tulip/poplar before moving on to more dense timbers. Wood such as oak is much tougher so a little more difficult to work, with the added blunting effect it has on tool edges meaning more regular sharpening is required. That said, the techniques to work these timbers are exactly the same as described for the softer timbers.