Questions about my cnc sherline mill

I just recently purchased a Sherline 5500 mill with a Microkinetics
conversion on it. I have some questions that I seem to be having more
trouble than I thought finding the answers to.
here is the ebay link
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1. When I turn the handles that are attached to the stepper motors
there is quite a bit of resistance and a sound kinda like that of gears
turning. Putting oil on my machine helped a bit but not much. The
question is, is the resistance because of the stepper motors or because
something is wrong with my mill.
2.What's a collet? Why do I need it? Where the heck does that long bolt
thing go(I could be getting two things confused). Why can't I just use
a chuck to hold endmills.
3.What are some things I should know. I mean.. most of the sites on the
net go like this. Here is the box my mill came in! Oh look I put it
together! Look how it works! yay! They rarely tell me anything tho.
Things like what not to do ever. Or what to adjust most often. etc..
4. Is xylotex a good brand as far as controller cards go?
5. With the mill came 4 endmills, a jacobs chuck, and a hand-tighten
jacobs chuck. What other tools/accessories will I most definately need
before I can cut something?
6. Any other tips?
Reply to
DammitCoetzee
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1. Yes, you are feeling the resistance of the stepper motors. I doubt that something is wrong with your mill unless the stepper motor is misaligned with the leadscrew (the thing that moves the table or column). 2. Collets are used to hold tools (milling cutters) or parts (in the lathe). The long bolt thing is called a "drawbar" and is used to pull the collet tightly into the motor spindle. Using a chuck to hold an end mill is a mistake. The chuck does not have the clamping strength or precision to hold a mill.
3. Start at the Sherline homepage,
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Try a Google search on sherline. You will get many hits for tools, accessories, and tips and technicques. But the Sherline homepage is still your best bet!!
4. I have no experience with CNC controllers.
5. Get the rotary table and a machining vise. Get the Sherline online catalog. It has MANY tools and accessories for the mill.
6. If you've never used a vertical mill, big or small, my advice is that your read any Sherline instructions you can get your hands on BEFORE your start trying to make chips. If you don't take GREAT care when you are machining, you will be made very unhappy very quickly. I am not a machinist by trade. I've had a Sherline mill and lathe for about 3 years and I have 3 rules: 1.Safety, 2.Safety, 3.Safety!!
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Reply to
Perry Murlless
Stepper motors have a property called "detent torque". The rotating part of a stepper motor has a bunch of teeth on it. These are magnetised. They align themselves with teeth in the stationary part of the motor. When the motor is rotated by hand it will move in jerks, not smoothly. This is called "cogging". The force it takes to turn the shaft from a stop is the detent torque. This force will give you a rough idea of the torque the motor will produce when powered up. By the way, don't take apart your stepper motors. Some motors will lose a good amount of magnetism if this is done. This will in turn reduce the torque the motor will produce. Your mill may have gears or a belt and gears between the motor and the leadscrew. This may be the gear noise you hear. A collet is basically a sleeve with slots cut in it to allow it to collapse. The outside will have a taper on all or part of it so that when pushed or drawn into a hole, which has a matching taper, it will collapse. A tool is inserted into the collet and it is pushed or drawn into the hole. As it collapses it grips the tool rigidly. Much better than a chuck. Chucks are good for twisting loads but not side loads. Collets are good for both types of loads. And cutters are often subjected to side loads. Collets are also used to hold the work. So if you are using a lathe to turn parts a collet can be used to hold the material you are turning down. Anothe big advantage of collets is the ability to make sure that whatever it is holding is held concentric with the spindle axis. This ability of course depends on how accurately the collet is made and how concentric the hole in the spindle is. But with acurate collets and spindles it is easy to get the part being held to run out no more than .0002". That long bolt may be what is used to draw the collets into the spindle. As to your other questions, you're gonna have to get answers from someone else. ERS
Reply to
Eric R Snow
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Most likely it is OK. As others said, cogging.
Wander around Sherline's web site:
They have pictures of all parts and accessories, including the collets and drawbar (long bolt). Everyone tries to mill using a drill chuck sooner or later. It works for a short time, but the chuck will loosen and ruin your work and maybe break something, maybe you.
Xylotex is a popular driver board. It is a bipolar driver which is stronger than a unipolar driver. Their web site is here:
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The endmills you got are 4 flute. Most likely not center-cutting. This means they will not plunge cut like a drill bit, but only cut from the side. You will probably want to get some 2 flute endmills as they will center cut.
You will eventually want a larger stepper motor on the vertical (Z) axis. There are also many sites in the web with modifications such as springs or counter weights to help support the weight of the motor (to put off getting a larger Z axis motor). Note that your motors are NEMA 23 size.
You didn't state the intended use of your new toy. What else you will need is dependant on that. For example, if you need a 4th axis (cnc rotary table), you may need a 4 axis controller instead of the cheaper 3 axis card. Xylotex makes both. You may opt for the 3 axis now and add a single axis controller later, if you need it. For things like thin gear cutting (clockwheels) you can fake it with a 3 axis controller by driving the 4th axis from one of the other drivers if you aren't using it.
BTW, your machine looks remarkably like mine. I got the X and Y motor mounts from a friend and made the Z axis mount. I have since upgraded to the sherline motor mounts. You can see mine here:
Click on "CNC Adventures"
Reply to
Ron Thompson
The z-axis motor is supposed to be 112oz-in and the other two 83oz-in I might get bigger ones if these are too weak but i dont really know yet because im still waiting on my paycheck so i can get the xylotex card
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I'll be using the mill mostly for robotics and hopefully making circuit boards. I'll probly be cutting into any material ranging from balsa to aluminum. I am going to get the 4 axis card because as soon as I stop being poor I want to get a 4th axis setup as well.
I already had your site bookmarked =P As for the motor mounts I have, they are amazingly sturdy and seem to be very well made. Also, how is that dremel mount working for you because I have a big chunk of 1/2" thick aluminum plate lying around...
Reply to
DammitCoetzee
The Micro-K mounts are plenty sturdy, but the Sherline mounts have ball bearings in them. Cutting friction is almost as good as bigger motors. It helps with the speed, too.
The dremel mount works fine, but I don't use it much. Note the base is 1" thick to allow the Sherline mounting system to work.
I had thought about making a casting that would be easy to machine for the next version (if there is ever one). The dremel doesn't make a very good mill head as the runout is too great. It is much lighter than the stock Sherline setup, though.
Reply to
Ron Thompson
Is the MircoKinetics drive box hooked up and turned on? If so, you are fighting the motors and drive, so no surprise there is considerable resistance. If disconnected or off, there should still be some resistance from the motors, but much less. If it is still stiff with the drives off, then you have binding of either the screws/nuts or the slides. Have you lubed the mill? The Sherline runs anodized aluminum against the same material, and proper lubrication is imperative to the life of the machine.
A collet is a slotted piece that holds different sized tools or workpieces in a spindle. You can't hold an endmill in a Jacob's chuck because of runout and poor grip. The endmill may actually fall out in some cases. If the Jacob's chuck is mounted to the arbor with a Jacob's taper, it will definitely fall off the arbor sooner or later. Have you ever dodged a spinning end mill in a chuck dancing across your machine? It is an experience you won't forget, I can tell you!
If you can find a machinist's short course on the web or in book form, check it out. There is a lot to know about work holding, setup, capabilities of the cutting tools, speeds and feeds, how to machine parts accurately, properties of materials, it goes on and on.
An edge finder to locate the corner of a piece is handy. Collets as mentioned above. (I usually use end mill holders, but they are hard to come by for the Sherline, I think.) A vise and parallels, a dial indicator to accurately align the vise.
I hardly know where to start!
Jon
Reply to
Jon Elson
You should join the Sherline group on Yahoo:
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Reply to
Emmo
Thank you all for the help so far. I belive I've figured out the source of the resistance while turning the handles. It seems that the things (I really dont know what to call em) connecting the stepper axles to the lead screws arent properly adjusted. At least thats what i'm assuming. I really wish I had another sherline around so I can figure out what kind of resistance normally exists when turning the handles. But the motor is much much much easier to turn without it being attached to the lead screw so I suppose I will have to fiddle around with the things for a couple of hours before they work right.
Anyway. Tips/links on how to adjust these properly would be rad.
Btw. The ends of the lead screw and axel look like this: ________ \_______ | | -----------------
and the thing that connects them has 4 screws off set at 90degress from each other like this. __ __ __ _||_ __||___||__ / \ | | | |==| | O O | \____/ |___________|
sorry bout my shoddy ACII art. I hope that made sense
Reply to
DammitCoetzee
Yeah, I'm not very impressed by the Sherline shaft couplings. They should be using helically-slit couplers, but those cost $30 or so. There are some alternatives, but the rubber shaft couplings tend to get sloppy after a while. Taig uses two steel bars with 4 holes near the OD. 4 pieces of Nylon tubing go in the holes of both ends, forming a somewhat resilient coupling, and allowing small shaft misalignments without putting radial forces on the shafts. The couplings you have offer no relief of these forces, and so you are bending the shafts all the time. The only way they can work is if the shafts are in very precise alignment. It may be possible to tighten the coupling first, then secure the motor mount. You might even need to open up the holes for the mounting screws.
I do know that some people have had the leadscrews and/or motor shafts snap off from these forces!
Jon
Reply to
Jon Elson
End mill holders for the Sherline can be easily made. Taig sells short pieces of round stock that are pre-drilled and tapped with the spindle thread. You will need to face off the end a little to make it screw on to the Sherline spindle and cut it a little shorter then drill the holes for the end mill and set screw. Careful work will result in very strong holders. They occasionally appear on ebay.
Reply to
Ron Thompson
Solid shaft connectors seldom work well. On a Sherline with small motors you can try fuel line hose and hose clamps to see if it improves. Use matching clamps and put the screws on opposite sides to help the balance. If this improves things, you can go for the helical couplers (your best bet). The Sherline mounts have helical couplers built in.
Reply to
Ron Thompson
Yea. they are about 7-20$, 5$ shipping on ebay.
Reply to
DammitCoetzee
Hehe.. you won't rest till I fork out the 200 some dollars for those serline mounts. But I'm poor as of now. With barely enough for a xylotex card, some random parts and gas for the school year.
I will search ebay and see if any come up but untill then I will either have to adjust these right (which seems like a good way to go since my y axis is pretty darn smooth while my x and z are out of alignment) or If you could elaborate on this fuel line coupler thing I might go that route.
Also, im still not understanding everything (and im pretty sure im gonna go buy that book on how to use a sherline mill/lathe) but if I get a collet set do I still need an end mill holder. If not whats advantage/disadvantage of the the two.
R> > Yeah, I'm not very impressed by the Sherline shaft couplings. They should
Reply to
DammitCoetzee
Btw. Im not using the sherline brand shaft couplings. these are microkinetics brand shaft couplings.
Reply to
DammitCoetzee
To use fuel line on the Y and X axes (axii?), get 1/4" rubber fuel line hose from an auto parts store. It has a string-looking braid in it for strength. Get the screw drive clamps while you are there. You will need about 2" of hose and 2 clamps per axis. The hose is about a dollar a foot.
Remove the solid shaft coupler and cut the hose to the same length as the coupler you just removed. Put the hose in place of the coupler (1/2 on the stepper shaft and 1/2 on the lead screw) Install the clamps making sure the screw of one clamp is on the opposite side of the shaft as the other clamp. This is not absolutely necessary, but every little bit helps. This is now a jury rigged flexible shaft coupler. I ran my machine this way until I got the Sherline mounts. I did use a solid coupler on the Z, But I made the mount and it was straight. If you want to use hose, be aware that the stepper will be 1/4", but the lead screw is larger.
Both have advantages and disadvantages.
The end mill holder will lock the end mill from turning by engaging a flat on the end mill shank with a set screw and prevent it from pulling out under cutting stresses. Also, they can be made in many sizes to accommodate your tooling.
Collets can hold well if tightened sufficiently and are much shorter. This can be a big plus on a machine of limited size. They only come in a few sizes from Sherline, though, as they must fit inside the spindle.
I have both, but seldom use the collets.
Reply to
Ron Thompson
According to DammitCoetzee :
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To me, it is simply a length of rubber or vinyl hose of the right size to slide over both the end of the leadscrew shaft and the motor shaft, with clamps to tighten it down over each. The flexibility of the hose allows some slight misalignment without problems. However, it will introduce some possible inaccuracy if the CNC is being used to control to precise dimensions -- but for use just as a feed, it should be no problem.
The collets are normally shorter, and waste less of the limited space between the spindle nose and the table. The end-mill holder totally eliminates the chance of the end mill slipping in the holder and cutting deeper, which can be a problem with heavy cuts and collets.
Enjoy, DoN.
Reply to
DoN. Nichols

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