Re: Using The Small Lathe Download
Phyllis Sterlin
Startup torque is not required, because in this type of application you can always start the motor unloaded; in fact, even if the motor had zero startup torque I could potentially add a small starter motor to start the main motor, if that would be better.
High-end lathes use a slipping clutch to protect the motor and gearing from excessive loads. The clutch is set to a torque such that the maximum possible load would not break any of the teeth in any of the gears.
It is important that the motor have strong inertial force because when metal is being cut sometimes a hard inclusion will be present so that the load on the motor can unexpectedly spike up for a fraction of a second when the cutter hits the inclusion.
It is important for the lathe's speed to be as consistent as possible because if the lathe has variability in speed as the load varies, then what will happen is the quality of the finish of the cut will be degraded. What is wanted is for that that motor to keep turning at exactly the same speed regardless of the variability of the load.
If money is no object then there are a lot of advantages to using a DC motor for a lathe. The ability to have continuously variable speed control is a huge advantage for a lathe. Compared to other machine tools a lathe has the specific problem that the circumference (and thus proper cutting speed inevitably changes as you work. Consider turning a 30mm bar down to 10mm, the circumference changes by a factor of 3 so any fixed cutting speed is going to be a compromise, the alternative being changing gears mid job.
It is also very useful to be able to fine tune cutting speeds on the fly when cutting threads or turning difficult materials. Being able to precisely adjust cutting speeds also lets you get more effective capacity out of a given motor power.
To give you some sense of power requirements a 500W lathe with a DC brushless motor will cope fairly well with drilling holes up to about 16mm diameter and just about manage 25mm holes with care in metals with good machinability (ie leaded or sulphurated mild steels or brass) and cuts up to about 1mm at a single pass.
In general DC motors tend to be a bit more compact for this sort of power requirement than AC induction motors also the ability to add speed control greatly simplifies the transmission design, although having a few gears is still an advantage.
My experience is that for a small lathe running off a single phase supply a DC brushless motor is a lot more usable and efficient in terms of overall production rates than an equivalent AC one. A 3 phase machine gives the best of both worlds but that is not an option here.
The working principle of a DC Shunt Motor is that whenever it is turned ON, then DC current flows throughout stator as well as the rotor. This current flow will generate two fields (namely pole as well as the armature).
Many owners enjoy making working miniature steam, Sterling or internal combustion engines. There are several shows around the country including the NAMES show in the West and Mid-West and the Cabin Fever show in the East that feature some outstanding efforts of this type. Others use their lathe to make parts for another hobby such as astronomy, microscopy or model railroading, shooting or RC model racing.
Some guys, like Bruce Simpson, get a little carried away and build things like your basic jet engine powered go-cart. Bruce, being from New Zealand, thinks this sort of thing is an entirely normal suburban activity. Of course the things you make can then be adapted to more advanced uses, such as using the jet engine to cool your beer.
The new one is .034 outer diameter, so it fits inside the .059 hole with lots of room to spare, and is drilled through with a #78 drill, . 016 in diameter. The outside diameter of the hypodermic needle is .018; too big to fit through the new hole.
Plastics such as Delrin, Nylon, Acetal and Teflon can also be worked with excellent results. Acrylic plastics such as Plexiglas are more difficult because they tend to melt, but this is a property of the plastic, not a limitation of the lathe.
In fact, as it came from the factory, the saddle was not machined square and the cross-slide was therefore not square with the ways. The result was that facing operations left a slightly convex cone shape on the workpiece instead of a completely flat surface.
HF sent me a replacement saddle at no charge, but before it arrived, I had already fixed the original saddle by milling the V-groove to be as precisely square as I could make it. As you can see, the results were pretty good.
The replacement saddle and the ones on my Grizzly 712 and Homier 712 were accurately aligned. Over the last few years the quality control seems to have gotten better and the problems I have seen on the newer lathes have generally been minor.
@Julien Try this first. You could mount it to the SO3
thingiverse.com Dremel lathe remix by bcooverMicro-lathe, great for dremel Also added a rail slider system to mount this to, idea is to screw the main part to a piece of wood, etc., and the slider piece moves in and out for mounting lathe pieces of varying lengths... This slider system is...
either build from scratch or find an old lathe for the ways.
create a steady rest with a pulley and chuck on one end, live center on the opposing.
motor with a pulley and v belt. done.
nice because you really only need the ways to be solid, steady rests should repeat pretty well if taken down.
Nice little lathe, I wonder if the motor will have enough power for anything but the smallest and softest material. At the moment, if I wanted to implement a 4th axis, I would consider the roller Y axis method but I would have to find plans or do my own design with all the pitfalls. I never seriously considered implementing a 4th axis since the stock Z of the Shapeoko does not give much clearance but now with the HDZ, it is something I may try at some point.
Would be interesting to do like I do with my laser, disconnect my Y axis and use it to turn the rotary. You would still have the x and the z. (which is what you normally use with 4th axis.) the Y would be center line of the lathe. The only issue is how to control the Y functioning as the rotary. Software allows you to change the steps and the diameter.
I have been considering purchasing a watchmakers Lathe and or a mini metal lathe for making stems, staffs and other parts. What is the difference between the two lathes and can I buy a mini lathe vs a used boley for example. I have attached a photo of both.
Same as mentioned. Gears, stems, precision you'll want a watchmakers lathe. Case work, movement rings, etc you'll get more mileage out of a minilathe. Or better yet, as my watchsmith mentor suggested to me, a vertical mill
He headstock bearings in a watchmakers lathe come in two types, adjustable plain taper bearings and very high precision ball races. The ballraces fitted to watchmakers lathes are of a far higher tolerance fitted to mini lathes.
You certainly can make watch parts on a mini lathe. I would recommend Cowells Super Elite. Very expensive, not sure, if they are still made if not they would have an equivalent. Do not expect to be able to make such high precision parts on these cheap lathes made in china. A mini lathe uses cutting tools that are set and held in the lathe.
One thing that has not been talked about is the lathe bed, if you buy second hand, make sure it is in perfect condition from one end to the other, take the tailstock off and check underneath it has to be completely smooth, no nicks or rough marks, any imperfections leave it as it will not be accurate in machining.
The best type of machine I have found to make tiny watch staffs and pinions is a watch lathe. The major issue I ran into was having the pinions break off after being turned down past .012 inches or less. A mini lathe has more mass and power with a trade off of less "feel". It was designed for larger size parts, such as clock parts, and can remove metal faster by taking larger cuts. Also, due to more size strength and power, a larger lathe will have less deflection from the cutter pressure thus providing more repeatable accuracy on each cut. That said, no matter how accurate the larger machine is, trying to turn a part down to .004 inches (.1mm) can be difficult or next to impossible due to overpowering the part. Larger parts can, in theory, be made on a watch lathe but a larger more stable lathe would be the better way to go for larger work. If you are going to use the machine to make watch parts (particularly staffs, pinions, stems, tiny screws etc.) I think you will find the watch lathe a better way to go. As I mentioned in previous posts, the Sincere Lathe is the going to be the best and most affordable option for this type of machine. You can always, at a later date, purchase a larger lathe in addition to this to make larger parts.
I would also like to mention that some watchmakers will turn the pinion down as far as they can with the turning process and then grind or file it the rest of the way on a Jacot Lathe. This is generally not recommended as it can affect the concentricity and cylindrical properties of the pinion. The final burnishing on the Jacot Lathe should only be used only for the final .01mm -.02mm. This is the difference between making a pivot and making something that looks like a pivot to the naked eye.
7fc3f7cf58