Catchless Turning With HSS Tools
Is there such a thing as turning without catches? What causes a catch in the first place? Can one turn a spindle without ever getting a catch? What about hollowing out a vase or hollow form through a small opening? Is it possible to turn a bowl without getting a catch?
What is the secret to Catchless Turning? Here is what works for me consistently.
We all get catches until we grasp one simple principle, “Limiting the depth of cut.” In order to understand how to do that, we have to separate spindle turning from bowl turning. Let’s discuss spindle turning first. You have heard it before ABC, Attach, Bevel, Cut.
Attach the tool to the tool rest before contacting the workpiece. Rub the Bevel and bring the cutting edge to the cut with the bevel rubbing first. Begin the Cut and move the tool down the element.
A little song still plays in my head each time I turn a spindle project; attach, bevel cut, attach, bevel cut, attach, bevel cut, attach, bevel cut, attach, bevel cut, etc. The only time I get a catch, even with a skew, is when I lose focus and don’t do ABC. I haven’t had a catch on a spindle project in several years except when I have been distracted.
So how to you rub the bevel on a bowl blank? For simplicity sake, everything begins at the centerline or slightly above (cutting below center almost guarantees a catch). I attach the bowl gouge to the tool rest and anchor it firmly in place with my thumb. I slowly force the first cut about 1/8” inch deep. Then I have a ledge on which to rub the bevel. Inside or outside, it is the same. There is a second step when using a bowl gouge. Let me use a motorcycle hand grip as an analogy. You grip the throttle at idle and as you rotate the handle you open up the throttle and your motorcycle goes faster. In turning, idle is with the flute parallel to the floor. Some call this the “Closed” position. As you rotate the gouge toward vertical, flute facing up toward the ceiling, you give it more gas or accelerate the depth of the cut. This is considered the “Open” position.
Therefore, start at idle - fully closed, cut your 1/8” ledge, then slowly rotate toward the open position until you are comfortable with the amount of shavings and hold that position. Then move with the cut. Do this each time you approach the cut and you should never get a catch.
The exceptions are all carbide tools (which are scrapers) and all scrapers whether conventional or negative rake. Overly simple you say, maybe, but try it and see for yourself because wherever you go there you are. Here is my inspiration for this message:
Acts 28:26 ESV
“‘Go to this people, and say, “You will indeed hear but never understand, and you will indeed see but never perceive.”
Heb 4:12 KJV
For the word of God [is] quick, and powerful, and sharper than any two edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and [is] a discerner of the thoughts and intents of the heart.
2Kgs 6:17 KJV
And Elisha prayed, and said, LORD, I pray thee, open his eyes, that he may see. And the LORD opened the eyes of the young man; and he saw: and, behold, the mountain [was] full of horses and chariots of fire round about Elisha.
Left Pic: Open-very aggressive cut --------Right Pic: Closed-very little cut
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