Proper Toolrest Height

[blackhorse]

As a beginning turner, I still get confused about proper toolrest height in different situations. I enjoy both face and spindle turning. I have books by Ernie Conover and Richard Raffan, but nowhere is there a table or central spot showing the right height for various circumstances.

Any ideas?

Joe

 

[Bill Boehme]

Hi Joe,

I think that the reason that you don't see much information about tool rest height is that it is dependent upon several things like your height WRT the lathe spindle axis, the tool that you are using, the particular cut that you are making, the spindle diameter if you are turning between centers, and what feels comfortable. The main thing is to be able to present the tool's cutting edge to the wood at the proper angle without having to put yourself in an ackward position to accomplish that end. As a general rule, you will want the cutting edge somewhere close to the centerline. An example of needing different tool rest heights would be for using scrapers of different thicknesses on the inside of a bowl. You should have the scraper angled downward slightly and the cutting edge should be right on the centerline. The scraper that you are using may have a thickness between 1/4 and 1/2 inch. These factors along with the amount of overhang will determine the right height for you.

Bill

 

[Sean Troy]

Once you find the proper tool rest height for your tools, you can cut a peice of PVC pipe that fits over your tool rest post to the exact height that matches your tools correct height. You will never have to monkey around trying to find that correct height for each tool that way. Just slip on the correct PVC section for a particular tool. It makes it easy to change tool rest direction without losing the correct height.

 

[MichaelMouse]

Depends on how you cut. I want to be on centerline or a tad above with the most forward part of the tool, so mine always moves to compensate for size and slope of gouge. As someone else mentioned, you'll want it a bit higher than centerline for scrapers with a burr. Lower if you hollow with a pointed or fingernail gouge.

About the only thing that's bad to do is cut below centerline on convex shapes, or much above on concave, where a bit of upward motion on the engaged portion of the tool can feed the handle to you if it touches the work.

 

[jimvogel]

Tool Rest height

When I am teaching a begining turning class I teach the students about tool rest height. This is a very important part of turning. If set to the wrong height you will incure catches, gouges, poor cutting and, lack of tool control. When turning on the outside of a piece, as in spindle or outside a bowl or box, to set the rest so the cutting edge of the tool being use is at or just below center line of the axis. This is done so if the tool should catch it will be pushed away from the wood. If the cutting edge is above center line when you get a catch then the tool is pulled into the wood causing much damage.
When cutting on the inside of a piece as in the inside of a bowl, box or hollow form the rest should be set so the cutting edge is slightly above the center line. Again, if the tool catches it will be pushed away from the wood.

I also explain that the height of the rest is differant for each person, due to thier height and how the hold the tool and what tool they use. This is why I stress the relation of the "cutting edge" of the tool in relation to center line. As I do the class I will go around and observe how they are cutting. I will have them adjust the tool rest and cut again so they see and feel the differance. Most beginners forget to readjust the tool rest when they change tools. I encourage students to try differant height when they get home to get the feel of what works best for them with thier tools.

Nothing can replace experience. After a while a you will know what height to put the rest at. The best advise is turn every day and observe what makes the best and simplest cut with least effort on your part.

 

[David Somers]

Once you find the proper tool rest height for your tools, you can cut a peice of PVC pipe that fits over your tool rest post to the exact height that matches your tools correct height. You will never have to monkey around trying to find that correct height for each tool that way. Just slip on the correct PVC section for a particular tool. It makes it easy to change tool rest direction without losing the correct height.

I do something similar with my rest, just using washers with 1" diameter holes. Once I know how many washers a tool needs (typically 1, 2 or 3) I will write that number on the tool shaft with a sharpie. Either way....its a quick change and has helped my turning technique by giving me good repeatable positions to work from.

You might also check the lathes height in relation to you. My 1642 is at a perfect height for me as is. But for my wife and our neighbors son who have both started turning some and use my lathe I made a stand for them that puts them at a comfortable height. It slips under the lathe so it is easy to get out of the way otherwise. I have always been told that the bottom of your bent elbow should be at the center of the spindle. That seems quite comfortable, at least for me.

 

[MichaelMouse]

When I am teaching a begining turning class I teach the students about tool rest height. This is a very important part of turning. If set to the wrong height you will incure catches, gouges, poor cutting and, lack of tool control. When turning on the outside of a piece, as in spindle or outside a bowl or box, to set the rest so the cutting edge of the tool being use is at or just below center line of the axis. This is done so if the tool should catch it will be pushed away from the wood. If the cutting edge is above center line when you get a catch then the tool is pulled into the wood causing much damage.
When cutting on the inside of a piece as in the inside of a bowl, box or hollow form the rest should be set so the cutting edge is slightly above the center line. Again, if the tool catches it will be pushed away from the wood.

You sure? If the tool is below center on a convex piece and tips up, it is carried and forced between the work and the rest. If slightly above when it tips up, it's into thin air. Opposite for concave. If it tips down in either case, you wedge. Why you want the rest as close as possible

Presumes the bevel being referenced, of course.

 

[blackhorse]

Hmmm. I love my new PM 3520B, but it's kinda tall. I'll check my height on it tomorrow.

Joe

 

[pencheff]

stealth

Hmmm. I love my new PM 3520B, but it's kinda tall. I'll check my height on it tomorrow.

Just had to work in that "my new PM" into the thread didn't ya? Nice subliminal gloat.

 

[hockenbery]

foremost the tool rest should be set so that the wood does not drive down onto the the cutting edge of the tool. How you hold the tool especially handle angle to floor will affect this cutting edge angle. the good tips mentioned above are to get an efficient cut and keep wood from driving onto the cutting edge.

For bowl gouges on bowls using a bevel ridding cut I have my students set the tool rest so that the cutting edge is at center when the gouge is held level to the floor. This works and I have them use the tool relatively level.
I the rest is below center the wood can drive down onto the cutting edge resulting in catches or at best making the tool difficult to control.

for scrapers it is important not to let the bevel contact the wood since the wood will drive onto the tool. Thus inside a bowl the tool rest should be above center. If a scraper is used on the outside of piece the tool rest should below center.

For spindle work with gouges and skews the tool rest should be at center or a bit above. I like the tool rest set so that I cut above center for larger spindles and right at center on small spindles thse at 1/4 " or so.

happy turning,
Al

 

[Ziffy]

I'm glad tool rest positions came up, as I've been pondering this question... I have a Delta Midi-lathe, and when I am working the inside of a small bowl, say 4 - 5 inches diameter, it seems that I can't get the tool rest LOW enough to keep the bevel riding when I'm reaching into the bowl. Am I doing something fundamentally wrong, or is this a potential design flaw on this lathe?

Brian

 

[MichaelMouse]

Choose another gouge. I take it by your statement that you're trying to use a fairly steeply ground fingernail gouge of some sort. Why not peel with a forged pattern gouge? Gives you the same edge to work presentation at nearly 90 degrees to the rest that a fingernail gives you with the handle bumping the banjo or ways. Plenty of room, just trail the upper edge a bit for good skew to reference where you've been, letting the natural curve of the tool make a progressively thinner cut from bottom to top.

 

[pencheff]

Why not peel with a forged pattern gouge?

And a "forged pattern gouge" is what exactly? Remember those of us who've only been turning for a few months need definitions and pictures with the terminology.

 

[Ziffy]

thanks for asking that Greg... I didn't want to sound too dumb!

Brian

 

[MichaelMouse]

Old days before they had good milling equipment, they forged gouges into swage blocks or dies to form them. Additional benefit in aligning the particles and toughening the steel. Made a tool of uniform thickness, which keeps the heel from bruising your stock as you try to go around a corner, because the grind is constant.

Not sure if forging improves high speed alloys, or even if they actuallydo it, but the pattern has returned. http://www.leevalley.com/wood/page.aspx?c=2&p=43177&cat=1,330,43164,43175 Europeans were still using it, called "continental" http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=tools-pkrd-gsg pattern, and certain famous name types as well. Rude Osolnik's gouge springs to mind.

At any rate, shallow designs mean you can get more bevel on the cut with a thin shaving. If you turn your Irish grind or edge grind cylindrical gouge nearly vertical, you'll see the same presentation the shallow gouges give at 90 degrees to the rest. Of course the support available from the rest, and thus, control, is better closer to ninety. Not to mention the gouge won't dig in like the nose of a swept wing type can if you overtilt.

Think these are already on the forum, but here's a hog and a peel.

 

[hockenbery]

Brian,
Hold the gouge level with the floor with flute pointing straight up and set the tool rest so that the cutting edge ( bottom of the flute is exactly on center).

This is the correct tool rest height. Unless you have an after-market toolrest or a really big gouge, I suspect tool rest height is not the problem.

If bowl is deeper than wide you may not be able to ride the bevel because the gouge will hit the rim of the bowl. Wider shallower bowls are easier shapes to ride the bevel to the bottom and quite often better looking.
For very deeper bowl you will need to use a gouge with either very short bevel or one with a steep bevel angle something like 80 degrees.

To shorten the bevel you can use a smaller tool or grind the heel from the gouge you are using. The shorter bevel will probably allow you to ride the bevl from rim to bottom. Using a gouge wilth a bevel angle of 80 degrees will also let you ride the bevel rim to bottom. If you are more experienced, using a shear cut with a side ground gouge effectively shortens the bevel.

When Jimmy Clewes taught a workshop at MD Hall he had the students turn a spherical bowl with the top 1/3 open using bevel riding cuts for the hollowing. This required a long bevel for inside the rim an intermediate bevel for the bulge and a very short or steep bevel for the bottom. I thought that was a wonderful teaching exercise.

happy turning
Al