spindle tasks

[Charlie Knighton]

i attended Allan Batty's rotation @nc symposium twists walking stick
i also inspected Stuart Mortimer's spiral finals in the instant gallery and was very intimidated. Allan suggested we buy a book for all the different kind of twists, the one pictured is a left handed double barley twist. i did purchase a book by Bill Bowers which has more information than i will ever need.

when i was 1st turning the dowell, i should have used a steady rest. i do not yet do many finals, and with this dowell i ran into some vibration. i assume that is the harmonic balance???? factor i have seen referred to. could someone please expain what is going on 😱 and what should be done to reduce or elimate it.

 

[john lucas]

Charlie it is flex in the wood. some call it chatter. It will challenge you. To reduce it there are several things that help. One is to make sure you tool is really sharp. Put less pressure on the bevel of the tool. A really sharp tool lets you do this. Use your fingers on the back side to counter the pressure from the bevel of the tool. If you get it perfect, no chatter.
This is harder than it seems and takes a lot of practice. If you are burning your fingers you are pushing too hard on the bevel and on the wood. Try being lighter with the tool so your hand can push lighter. Turn the speed down if necessary.
Hold one end of the dowel in a chuck and then reduce the pressure from the tailstock as much as possible. This will help reduce the chatter.
You didn't say what tool you were using. I normally use a skew for something like this however sometimes a tool with a smaller radius edge such as a 3/8" spindle gouge will chatter less.
Last but not least is to simply add a steady rest. Turn the middle down close to final size. Put the steady rest here and then turn the rest of the spindle.

 

[Richard Baker]

Charlie, Probably not related to natural harmonic frequency. Just result of deflection due to pressure of the tool as John described.

Most structures do have one or more natural harmonic frequencies which are functions of the structure, material, and load(s) imposed. When perturbed, things tend to vibrate at their harmonic frequencies. Some obvious examples are guitar and violin strings and that famous suspension bridge that collapsed.

 

[Charlie Knighton]

tool

You didn't say what tool you were using

i was using the wing of my roughing gouge and was in the middle of the dowell. another of my shortcomings is skew use, i seem to have better control with the wing of the roughing gouge vs skew. Jimmy Clewes was doing something when he made a comment and then showed how to get some fine shaving with the wing of the roughing gouge.

i believe yall are dead on with the chatter thing.

i have a spindle detail gouge, i guess maybe i should also try it, the dowell was so large i did not think of using a smaller tool.

 

[Joe Greiner]

Here's a simple steady rest I made for production turning of birdhouse earrings. The slot and pivot accommodate different lathe swings. Almost not visible is a wick for lubrication. It's sized for 1/2" dowel, but can hold slightly larger.

{I installed the wick after taking the second picture.}

Google ["birdhouse earrings procedure"] for more.

A "string steady" also works well, with minimal tooling. Google that too.

 

[MichaelMouse]

i was using the wing of my roughing gouge and was in the middle of the dowell. another of my shortcomings is skew use, i seem to have better control with the wing of the roughing gouge vs skew. Jimmy Clewes was doing something when he made a comment and then showed how to get some fine shaving with the wing of the roughing gouge.

i believe yall are dead on with the chatter thing.

i have a spindle detail gouge, i guess maybe i should also try it, the dowell was so large i did not think of using a smaller tool.

The wing of the rougher equates to a straight chisel, which is a great tool for planing, and has no nose to catch an unwary user. Great tool, easy to teach and use.

Can't be for sure that the exotic stuff wasn't a factor, but mostly the spindle starts to squirm because cutting face grain is different than cutting quartered grain. The hard annual rings push away from the tool, while the softer earlywood peels away faster. You may even notice this in sanding. That's why changing speeds or feed merely tightens or loosens the pattern. Nothing harmonic about it.

Standard method of control is a steady, which can be as simple as rolling the fingers of the "off" hand around the piece as the palm holds the tool to the rest. Thumb goes to maintain bevel rub. The simple old Bodgers' steady is the one I used before I got the Oneway. It's a notched wedge with a weight to hold into register. Thought I had a drawing somewhere, But can't find it. It's in The Practical Woodturner among other places.

The detail gouge, if it's what Packard calls one, has a severe case of the worst characteristic of cylindrical gouges; it's far thicker at the center of the flute than the wings. Forces you to a higher sharpness angle, which requires more tool pressure and creates squirm. Much better choice would be one of the forged pattern gouges with their consistent thickness and bevel angle. They work on the same principle as your rougher. Best choice is a long-bevel tool which peels with minimal press at a low angle.

 

[john lucas]

Charlie I use the wings of my rough out gouge for almost all fine tuning of the shape after initial roughing. They work fine. All of the things I said above apply to this tool as well. When I do have chatter and have created a spiral I try to change the orientation of the tool so that it cuts at different angle or maybe even a different direction. Otherwise it just bounces off the already created spiral and makes it worse.

 

[Charlie Knighton]

thanks for all the help everybody 😀

 

[john lucas]

MM I respectfully disagree about the detail gouge. It is one of my favorite tools. I have 2, a 3/8 and 1/2" thompson detail gouge. It's not about the shape it's about how it's used. I find the thickness an advantage. What I like about this tool is the small area of cut. Partly because of the thickness of the tool I can remove the smallest amount of wood with no chatter.
I can take out tear out with this tool that is difficult to remove with other gouges either spindle or bowl. I'm not sure but the reason almost has to be it's small cutting area. These gouges are sharpened to the same angle as my other spindle gouges.
With my larger forged gouges I sometimes will get tearout on woods with squirly grain. The same is true with the skew. When this happens I grab the detail gouge and can usually get rid of the problem. It also works well when I have chatter problems. I can gently remove just the tops of the spirals and get it level again.
The only advantage I see of a regular forged spindle gouge is for large gentle curves such as the Rude Osolnik candlesticks. It seems easier to get a really smooth controlled arch with the big spindle gouge or skew. The detail gouge is much better for smaller beads, balls and coves. At least in my opinion.

 

[MichaelMouse]

Disagree about what? Suitability as a planing tool? Compared to tools like those with straight edges like skews,chisels or Bedan? Or the broad radius gouge with uniform thickness which can be skewed to the motion of the wood to effectively lower the sharpness angle?

Unless you take a bunch of metal off of the thick part of the tool, you can never plane - and the thread was about planing - with a detail gouge, regardless the name invoked, as well as with any of the other tools mentioned.

Then again, none of the actions you mentioned in your dissent have to do with planing, so perhaps you're really saying that when it comes to Vitamin C you prefer an orange rather than an apple? You can remove small digs fine with ANY tool with a small contact area, but it comes at a price. If you remove material from a narrow area, you must then find an effective way to remove the majority of the material elsewhere to get it to the same level.

The detail gouge gets in its own way when you try to plane, forcing you to a higher angle, with the greater resistance that entails, and makes the piece squirm more. Third law, after all.

 

[john lucas]

MM I'm not sure what your saying about the higher angle. The bevel of my detail gouge is the same angle as my forged gouges. I might have to set the tool rest lower because the tool is thicker which makes the cutting edge higher but the actual angle of cut is the same.
As far as planing cuts I think the length of the bevel and your tool control has more to do with how smooth an arc you can get while doing a planing cut. I have a think skew that is ground to about a 90 degree included angle. It has a very short bevel. It's difficult to get a long clean cut with that tool but because of the short bevel I can cut fairly shallow coves with it.
My normal skews are ground to about 35 degree included angle the bevel is quite long. This gives me much more control when doing long straight cuts or long curves. The same is true with my forged spindle gouge.
My detail gouge could be the same with a long bevel except that I purposely grind away most of the long bevel to give me a very short primary bevel. This lets me use the tool for what it's best at which is tight coves and reaching into tight areas. With proper tool control (I use my body instead of my hands) it's still possible to get long sweeping curves using my small detail gouge.