Contents

Scope
Selling Your Wares
Tool Chatter
Tool Bounce
Tool Grab
Making Your Own Tools
Honing My Tools
Making a Large Disc Sander From Your Lathe
How to Inlay a Band on a Bowl

 
    

Scope

I added this page only to share some things I have learned about turning and to share the view point of an engineer on some wood turning issues and facts. If you feel that I have misstated something please feel free to email me and I will gladly take a new look at the matter. If you offer something special, I may add your input to this page and give you credit for it. Some things I say are simply my own preferences, but if you tell me yours I will likely add them or possibly change my own commentary if I see an error in my ways. The subjects below are in no particular order and certainly are not all inclusive to woodturning. This is not a research paper of any kind, but as I do research in the future and receive comments from others, I may very well edit this page with additions or changes.

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Selling Your Wares

1) Get a sturdy tent for a show booth. I like my "Easy Up".

2) Get a credit card machine. You can't do much without it. I highly recommend Merchants Warehouse because the cost of their service is low, they are easy to work with and they don't lock you into a contract. I plug them on my home page and here because of my own positive experience. Spend a little time on their site.

credit card processing and merchant accounts 

3) The more you have the better. Have some low price items for the non spenders along with your finer pieces. They can be a money maker.

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Tool Chatter

This phenomenon is about vibration and resonance. Your tool may "sing" at a certain frequency or chatter at a certain rate when you apply it to a given piece of wood, just like a guitar string vibrates at a certain frequency based on it's tension and weight. When all the forces are put together, the tension, the weight, the amount and frequency of stimulation will cause a vibration to happen at a certain "favorite" frequency called the resonant frequency. If the factors are just right, the resonance may be very strong and very destructive to your project. The factors that contribute to this are things like the weight of your tool, the weight, turning speed and hardness and rigidity of the wood piece, and the type cutting tool. If you allow chatter to continue you may end up with an uneven or wavy result on your piece. I find the solution rather simple. If you change any of the contributing factors, you will change the resonant frequency or stop the vibration entirely. You can change the turning speed, change tools such as from a bowl gouge to a scraper, change the position of the tool rest or change the pressure you apply. All these changes will alter the rate or amount of stimulation that are causing the chatter.

I generally find chatter to be a bigger problem when turning harder woods and when using tools that are a little too small for the job. I like to change tools and speeds and positions regularly even when I don't really sense chatter, because I think it often results in a smoother job. Don't confuse tool chatter with tool bounce.

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Tool Bounce

Tool bounce is when your cutting tool is pushed away from the wood instead of penetrating and cutting. This is basically because the tool is not sharp enough to cut the wood with the wood's given hardness and the amount of pressure you are applying. If you allow the tool to bounce too long you may produce a wavy surface that is rather difficult to smooth out. Sometimes the uneven hardness of the wood grain creates a bounce each time the tool comes to the harder portion or grain direction.

To correct bouncing you can sharpen the tool, increase the applied pressure or change to a different tool, such as to a tool that takes a smaller bite from the wood which effectively increases the pounds per square inch that you can apply. When the problem is exacerbated by uneven wood hardness, I find it helpful to occasionally cut for a while with a very light pressure which seems to smooth the cutting when I resume my normal cutting pressure.

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Tool Grab

Oh how we hate this! And it can be a little complicated too. Basically what happens when the tool "grabs" is that the tool is trying to bite off so much wood and the push back is simply more than we can hold off. The tool often grabs because the sum of the forces and directions of forces (vectors) are in an unstable mode. All in one instant the tool bites too hard and the deeper it cuts, the more it pushes back, and the more it pushes back the deeper it cuts and finally something either breaks or it jerks the tool out of your grasp. You often end up with a nasty gouge in your work and sometimes a numb hand as well. What are all the factors here?

1) The type of tool you are using has much to do with this.

Tools with aggressive cutting tips are more prone to "grabbing" than the less aggressive cutting tips.

Tools Tips

Note how the aggressive tip can easily be angled so that it draws the tools more deeply into the wood. This is not to say you shouldn't use an aggressive tool, but if you are having a grabbing problem you may want to change tools. Notice that on some tools such as a bowl gouge, the sides of the tool may have an aggressive attack angle while the tip is less aggressive.

2) The angle of attack is a big factor. Note that the angle of attack is based on the direction of movement of the wood compared to the angle of the top of the tool. This is easy to determine in doing spindle type turning.

Angle of attack spindle

Note that with the tool rest positioned far from the work as shown, the steep attack would be unstable and the tool is apt to grab. If the tool catches, it will tend to draw the tool deeper into the wood. In the figure showing the shallow attack, note that if the tool were to catch at all, it would pivot the tool on the tool rest in such a way that the tool would be drawn out of the wood, a more stable scenario.

When cutting on the inside wall of a bowl especially as in hollowing a bowl that has a smaller top opening, notice that it takes a little analysis to understand exactly how the wood is moving. In the figure below the tool rest is shown adjacent to the bowl's center of rotation.

Wall of Bowl

When the tool rest is between the rotation center and the wall being cut, if the tool catches in the wood the tool will tend to spill from the wood as it continues to rotate and is thus less apt to grab. Hence, the tool rest position shown above is borderline unstable. Move the rest further to the left than what is shown.

3) The bite of the tool is important. A tool with a wide or deep cut exerts a greater force on the tool and makes it more difficult to hold in a stable manner.

4) Leverage is a big factor. Depending on the power of your lathe, if the tool rest is positioned for example at the mid point of the tool length, the situation would be very precarious and unstable. Depending on the amount of tool bite, I like to only extend about 25% of the length of the tool past the tool rest. When doing deep hollowing such as in my wine decanters I make my own especially long and sturdy tools and I make small non aggressive cutting tips to use during the long reach.

I think it's human nature for a turner to use increasingly aggressive techniques until he encounters a problem such as the tool grabbing. Sort of the Peter principle. The first time the tool grabs, I would suggest that you should adjust your technique in the following manner:

First: Diminish the angle of attack.

Next: If the above doesn't work, reposition the tool rest closer to the work and higher.

Next: if the above is not possible, change to a less aggressive tool with a smaller (narrower) bite.

I don't recommend that you use ultra grab-proof techniques by any means because normal cutting angles do include a certain risk of tool catching or grabbing. You need to use certain aggressive techniques or you won't be a very effective wood turner. So perhaps the natural "peter principle" method is actually the best approach but just know how to make the proper corrections when you encounter the grabbing problem.

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Make Your Own Lathe Cutting Tools

Making tools is much easier than you may think. The only metal working tools you need are your grinder that you already use for sharpening, a drill or drill press, and an angle grinder with some cutoff wheels. A 1/4" 20 TPI Tap. A tap handle. You can get all this stuff at Lowe's or Home Depot for about the cost of two or three purchased lathe tools; maybe even less with the growing cost of purchased tools.

Tool Materials Required:

Round bar stock - Suggest 1/2" to 3/4" dia. (or more) - Lowe's, cheap

Some 1/4 - 20 preferably stainless round allen head screws to hold your tips onto the bar. Length should be a generally about 2/3 the thickness of your round bar stock. (You will cut them off if they protrude through the bottom of your tool)

A square strip of hard tool steel 3/16 to maybe 1/4" thick and 1/2 to 3/4" wide. Find this in an industrial supply house and select the thickness and size based on how large a tool you want to make. I keep several size bars of tool steel in my shop and can make a new special tip from one of them in about 20 minutes.

Some wood for a handle - doesn't need to be beautiful - I'm not going to tell you how to make a handle. Use some crazy glue when securing the handle on to the round bar. (Do this last)

1) Use ypuir angle grinder with a cut-off wheel to cut a flat spot in your round steel stock essentially at the center of the round stock. Don't be stingy on the length of your tool. The only time it's too long is if you try to put it in a suite case.

Tool Bar cutting

Get the flat spot very flat - flatness makes your tip stay put.

2) Using the drill bit provided with the tap, drill through the center of the flat spot and gently tap a 1/4" 20 TPI hole. Use your regular grinder to round off the bottom of the end of your tool.

Make some cutting tips for your tool:

3) Make a mounting slot. Put the rectangular tool stock in your vise and use the angle grinder to make a 1/4" wide slot. Test the fit using a 1/4 -20 screw to fit snuggly in the slot.

Make a slot

4) Shape your tip. Make an approximate tip shape by cutting to length and then cutting off corners etc. with the angle grinder. Perfect these shapes using your regular grinder with the grinder rest fitted fairly snugly to the grinding wheel. Some suggested final shapes are shown below. I have made and used all these shapes with success.

Tool shapes

You probably already know some shapes you would desire to have. Cut the tip out crudely using the angle grinder, then round the cutting edges out nicely with your regular grinder.

The tips I have shown are all scraper style tips. This is because they make a nice non aggressive tip for deep hollowing and they are also easy to make.

Finally,

5) Set your grinder rest at about 15 degrees upward and grind the resulting scraper angle on to the cutting edge by rolling it back and forth with your fingers (leather gloves required). Dip the work piece in water intermittently for cooling.

Grinding tip

 

6) Add a side control arm

When hollowing, a control arm extending horizontally to the left gives you control of your angle of attack when you are cutting blind. I have used both a screw and a weld joint to secure a control arm. Either way, it requires a nice symmetrical "V" be cut into the end of the side arm before attachment in order to secure the side arm well. Cutting a good "V" with an angle grinder is a little tricky by eye, but you can do it if you go slow with care.

side arm

Having the side arm screwed on and removable enables you to more easily change to a different length side attachment if you later change your requirement. Drilling the long 1/4" hole in the side arm is pretty difficult with a hand drill. You might not want to try this without a drill press. If you can weld, welding can permanently attach the side arm with ease.

Secure your favorite tip to the tool using one of your 1/4-20 stainless screws. If the screw tip protrudes past the bottom of the tool after securing the tip, cut it off flush using your angle grinder. You may like to use a brass washer under the screw head for a more secure and cushioned securing of the tip.

In tool use note that you can swivel the tip to the left or straight to optimize cutting on the particular surface you intend to cut. For example, turn it to the left for bowl walls or top hollowing, or straight for doing the inside of a bowl bottom or hollow form bottom.

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Honing my tools

I have honed tools with a leather wheel and compound to a mirror bright shine, but have seldom really seen an increase in cutting performance when I did this. I feel like whatever finer edge is gained by honing is gone in seconds of use. Now, I will make this comment: It could be that if were using a harder tool steel the honing would pay off better. I admit that I haven't tried that.

I do use a hand diamond "hone" for touching up my tools between major sharpenings. This, however, I consider to be a kind of "sharpening" since I actually hone in the direction that I grind (into the cutting edge) and I use the diamond hone to remove metal as opposed to creating/aligning "micro burs".

The question I ask myself is this: What do I want to do, sharpen and hone tools, or turn wood? Someplace there is distribution of work effort that allows me to get my job done in a reasonable amount of time. Right now I feel that this does not include regular honing, but I will keep my mind open to the opinions of others on this.

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Making a Large Disc Sander From Your Lathe

Disc Sander 1 and 2

My friend Brian Sykes showed me this and it works great. Do it like I did and buy an extra face plate to leave attached to this cool tool. Go to Woodcraft and buy some 12" (or whatever desired size) sanding disc stick-on papers. Take a piece of MDF, and cut to approximately round using whatever jigsaws or band saws you have. Attach the new faceplate to the center of the MDF. I glued an additional 6 inch square backing to the MDF to stabilize against warping of the MDF. Turn it to your desired diameter on your lathe and trim/sand the face until true. Stick the round sand paper disk on it. If you don’t like the price of stick-on sanding discs, you can cut and glue regular good quality sandpaper to the round MDF disc  using 3M Spray Mount Artist’s Adhesive. This adhesive does not stick very securely, but it has been secure enough to endure sanding use and old paper peels off very easily.

Safety:  I recommend using a face shield when turning MDF. Although the board turns easily, the waste that flies off is hard and hot and has a way of getting right past goggles and scouring your eyeballs.


Make a square sturdy heavy plywood box about the height of the center of your lathe to use as a project rest. Make the box so it can easily be attached and removed from the lathe bed. (I recommend a centered wooden twistable bar hung below on a verticle 1/4" carriage bolt. When the box is mounted in place, you can use crazy glue to attach two little guide boards that fit against the outside of the lathe bed. This helps facilitate quick square mounting.


For sanding segments with critical angles I attach a guide board (not shown) to the top surface of the box set to the horizontal angle I wish to maintain and held using a C-clamp.


Now you have a large disk sander you can use for flattening the bottoms of bowls or sanding segmented discs etc.

 

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How to Inlay a Band on a Bowl

Banded Bowl


Don't let this long winded process intimidate you - the whole thing except for the drying times only takes minutes.

Here's how I do it:

You can buy these inlay bands in Woodcraft stores or other suppliers. Your issues will be this: The band is not initially curved to fit a bowl, the ends need to meet with a seamless appearance, the surface you glue it on needs to be cylindrical and you need to cut a precise groove to in set it. Don't attempt to put a band on a tapered part of the bowl - it just won't work. These bands will only bend along one plane.

Shape the Band
You need a round object such as bottle or metal pan that's just a little smaller than your bowl in diameter to wrap your band around for shaping.
You need some paper towel or cloth which you will wrap around the band while it dries.
You need some duct or masking tape, a few pieces pre-cut to hold the drying band around the pan.

The Band Shaping Process
Put a couple tablespoons of water in a gallon size plastic ziplock bag and bring the water to a boil in your microwave. While the water is piping hot, roll your band into the plastic bag and seal it closed. Immediately place the bag back in the microwave and for exactly one minute turn on the heat while watching the bag expand with steam, killing the heat when the bag approaches swelling tight. Why the one minute? Because that's about how much the band can stand without coming unglued in the bag.

Quickly remove the band and holding the ends wrap it around your chosen cylindrical bottle or pan, wrap your paper towel or cloth around the band to hold it in place and tape it secure with your masking or duck tape. Since I offer no preventative safety tips herein, you may now soak your scalded hand in ice water as necessary.

Let the band dry completely on your form - you can speed this up by putting the whole thing in a very low temperature oven (100 degrees). You must not attempt to glue the band on your bowl if it's wet or you will have a mess that won't stick.

Prepare the Bowl
1) Get to the final stages of your bowl - nearing the final sanding.
2) The bowl needs to be perfectly round - so re-turn it if it is not and don't let it sit long before you apply the band. It may warp and mess you up.
3) Sand the band area smooth to make your groove cuts nice and clean

Cut the Goove
You need an inlay knife which has a tiny sharp blade with a sharp pointy tip, This is used to pre-cut edges of the groove and to cut the band ends. I think an Exacto knife may work OK if you don't have an inlay knife.
You need a cuttoff tool to turn the groove for the band.

With the lathe running, use the inlay knife pointed straight into the wood, with light pressure, make a single cut to about the depth of the band thickness for one side of your band groove. Be very careful not to let the blade walk across the bowl making threads all over the place. Hold it firmly against the tool rest but use delicate pressure into the wood bowl until you get some penetration.

Use a piece of the band to mark the position of the other side of the band groove - when in doubt, start a tiny bit narrower than the width of the band. Turn another precise cut for this other side of the groove.

Use your cut off tool to remove the groove wood to the depth of the the band thickness. Check the band fit and trim the goove for perfection. Don't widen the groove with the cutoff tool, but always make a new edge cut using the inlay knife. This assures a real clean groove edge.

Cut your shaped band a little longer than the required circumference and fit it into your groove, being sure you can press it all the way in, ALL the way around.

Glueing the Band in Place
You need Crazy glue (just a dab for starting things)
You need your favorite wood glue ( I like tightbond II or III)
You need some long stretchy band - rubber band (I use thin stretchy sewing cord (Wall Mart in the sewing section) Have enough to make 10 wraps or so around the bowl.

I recommend you do this with your piece still in the lathe so you may roll the peice while working glue etc.
1) Trim one end of your band along the pattern - it helps if the band pattern has diagonal lines in it since a diagonal cut is more invisible.
2) Put a drop of crazy glue on the end of the band and stick (the end only) into your precision groove and hold it downwith your knife until the end is firmly stuck place.
3) With the first end stuck firmly, flow an ample amount of your wood glue underneath the band all the way around. With your finger start at the attached end of the band and work it down tight into the groove. When you get to the other end, trim the final end while it lies right on top of the attached end and press it into place.
4) Wrap Your elastic band around and around tightly allowing the glue to squeeze out.
5) Let it dry, remove the elastic band and sand it in the lathe until flush and smooth.

You may be concerned when the band ends meet with the circumference having been dictated by other factors that are hard to control, that the pattern of the band may show an interruption. It will in fact do so almost every time. But guess what: If your meeting joint is real tight, in about 15 minutes you probably won't able to find that irregularity yourself and certainly nobody else will ever notice it. There may be some band patterns that would show the irregularity more than others, but most of them are very hard to detect. The eye just seems to look past it. Don't make pattern continuity a priority in this or you will go nuts for nothing.

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