This makes finishing the turning much easier. You only have one end to sand and wax with no extra nub on the end to deal with. Tenons are very useful in turning. You can make tenons to fit into various sized chucks or you can turn tenons on projects that will fit together for the project. When making a lidded box I turn a tenon on the bottom of the box. Turning a lidded box is a great turning project. The trick to this is the parting tool. You turn your blank round between centers on the lathe.
On the bottom end you make a tenon with your parting tool. Then turn your blank round and figure out where you want the joint on your box to go. The parting tool is going to be used to separate the lid from the bottom of the box. Move your parting tool away from the bottom just a smidge so you can see a small ridge.
When turning a bowl on the lathe and holding it by a tenon in a multi-jawed chuck the parting tool can be used to part the bowl from the lathe. Turn the outside of the bowl to your desired shape. Hollow the interior of the bowl and finish both sides of the bowl.
When you are ready to separate the bowl off of the lathe take your parting tool and part it off. To make the bottom of the bowl flat, even with some wood movement, angle your parting tool towards the center of your bowl. Not a lot, you are not turning another bowl. Just a slight angle will give you a concave bottom that will allow your turning to rest steady on a table. Another place the parting tool helps is with making shawl rings or jar lids on your lathe.
The more rigid the machine the easier it is to part things off. A parting tool properly set up will not leave a 'tit' so make sure things are on center. Same thing applies to a facing tool Look at your parting tool and blade and take note of the shape and set up accordingly. Wear safety glasses. Most of all keep at it.. As for size to be cut off.. Hope you find this helpful. Stay safe Calvin B. I heard somewhere that back in the day, many of the guys in machine shops wearing patches over one eye received those injuries doing parting operations.
When the blade snaps it must have a tendency to that particular region of the face. That reduces the slop of the compound from the equation. Hope this helps. Best regards, Bob. Join Date Mar Location Calif. FYI, the Aloris tool holder adds 4 degrees of back rake on their holders and this has proved to be a good compromise for general use.
The thin and tall bits are the easiest to use. In case you are wondering, the T type blades will work but the P types work much better and are so much easier to use and take less time and skill to sharpen. Do not grind on the top or sides, just the front-end. Put the tool on center, if you put the tip below center you run the real risk of having the part roll over the bit, this breaks things.
With HSS, a good dark cutting oil is a must. Just for fun I have tried ATF, hydraulic oil, motor oil, gear oil and a semi synthetic water based coolant and by far the best results and finish were obtained with the sulfurized, chlorinated, cutting oil. Decades ago I routinely parted off 1. I was using a Atlas with HSS in Armstrong tooling, set on large washers-shims in place of the rocker.
I almost forgot, this lesson you must not ignore. I ground one parting tool from HSS-Cobalt, which is shown above. A thinner parting tool would have been better. You have to remove more material to make a parting tool than most any of the other blade types.
Notice there is a lot of positive back rake on the tool as well as plenty of side relief. Keep in mind that parting off is a fairly demanding operation on any lathe. Rigidity is extremely important. I find that locking my carriage is an essential step to take in order to maximize rigidity. Another important step is to make sure the cutting tip of your parting tool is right on the center line of the piece you are parting.
Make sure your tool is exactly perpendicular to the axis of rotation as well. Another thought on parting is to try to do your parting as close to the chuck jaws as possible. This is another way to maximize the rigidity and make things go smoother. This is a more rigid configuration plus the tool will tend to pull away instead of digging in with this arrangement.
I have also heard the recommendation that you have to do parting operations at extremely slow spindle speeds, but this is not true.
It comes from the tendency of many machinists to be a little afraid of parting. It fully supports lathes and turning operations and will give you great feeds and speeds for all your turning jobs. Step 1: Part-off Tool Selection. As shown in figure 1, there are generally two types of part-off or grooving tools: HSS and tungsten carbide.
As usual, HSS is cheaper, tougher, and can be reground by hand once damaged. Carbide can tolerate much more heat, but once the insert is damaged it must be replaced with a new one. Figure 1: HSS part-off tool left versus indexable part-off blade center and carbide insert right. There are many different styles of part-off inserts depending on the type of material being cut and insert effectiveness.
In addition, carbide part-off inserts are available with high temperature coatings for use cutting ferrous and abrasive materials. Figure 2: Carbide parting inserts are available with different rake angles and coatings like titanium nitride TiN for use cutting ferrous materials.
Step 2: Part-off Tool Inspection. Inspect the parting tool closely before using. If using an indexable part-off tool, check that the cutting insert is in good condition. Figure 3: Video on how to properly sharpen and use HSS parting blades. Step 3: Maximize Cutting Tool Stiffness.
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