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    Default stepper motor advice

    Hi -
    I am looking to build a small table top CNC machine. I already have some 8mm rails and bearings around 19.5" long and mounts. I am going to use 1/4-20 screws and already ordered the bits from dumprstercnc.com that would be needed.

    I ordered based off a 5mm shaft on the motor I have. Shinano Ke STP-42D201-37 Stepper Motor 1.8/step 1.55ohm

    Now I am unsure if that would be a good enough motor for what I am trying to do. I want to cut and carve hard and soft woods and some light aluminum and brass.

    Thanks -
    Keith


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    Also does anyone know an easy way to get these gears off?


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    What are you planning to use as your spindle? Something like a Dremel, or something larger?

    If I have done my calculations correctly (based on the spec sheet at https://www.jameco.com/Jameco/Produc...DS/2158531.pdf), the rated holding torque of that motor is something like 44 oz-in. It is a fairly small motor. It might be suitable for a very small machine, but it is a lot smaller than the typical ones that I have seen people use in hobby CNC machines.

    Do you know whether that gear is attached to the shaft by a "press fit"? If so, perhaps a small bearing puller such as the smallest one shown at 3 Piece Two-Jaw Puller Set would do the trick, however I do not have any experience using that tool to do such a job.



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    Its pressed on really tight. Thanks for the links.

    what motor with a 5mm shaft (since I already placed the order with dumpstercnc.com) that would be better for a small machine like this?

    Thanks

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    Gold Member doorknob's Avatar
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    Do you have a diagram of the machine or a photo or diagram of a similar machine?

    As for the 5mm shaft, if you get a motor with a 6mm shaft would you be able to simply drill out one end of the shaft coupler to fit it?



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    true on the drilling -

    No pics really. Just going through electronics I have and seeing what I can build. Need motors than can drive something on 8mm rails. They are approx 19.5" in length for X and Y axis - so maybe 15 inches of travel.
    Want to cut or carve hard and soft woods and some light aluminum and brass.


    TB6560_4Axis_Driver and a smooth stepper controller





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    I think the motors will be fine for the thread pitch you have. The thing will be if your drive can spin those screws fast enough to get decent cutting speed in wood, and if so, how long will those AB nuts and leadscrews last?

    My best guess is that you'll run into problems cutting aluminum and brass with the rather small unsupported rails. It's no trivial thing even with supported rails.



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    Found a pic for type of machine I am going for but making it really small.



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    Default Don't push it!!!!

    I am reluctant to say that you can't do something when it comes down to cnc. It depends upon how much you know and how much you can give on certain goals.

    I have never cut wood. All I cut is Aluminum and I am still no expert. I just built my first cnc machine several months back and it's finally cutting in an acceptable manner after weeks and weeks of learning. Cutting Aluminum with the setup you propose would be difficult but helped greatly by the following things that I have learned. (With no guarantees it will work). I invite some of the gurus to evaluate my comments and correct or add to where warranted.

    1. Pay close attention to the rigidity of your bridge (The cross section that holds your Z-axis). It is critical to the accurate and uneventful cutting of Aluminum.

    2. A variable speed control such as the Super PID2 device would help greatly in controlling your cutting heat buildup, chatter, stability and torque. Most important for you will be torque.

    3. Some sort of blower will help to keep your cutting path free of chip build up in pockets, which can be a pain. Chip buildup can put unnecessary strain on your drive system, especially when plunging if not removed.

    4. Get use to slow cuts as you necessarily reduce your depth of cut and units per minute to match the strength of your drives. You may want to consider belting or gearing your X and Y drives for more torque.

    5. Make sure you use 4 flute end mills so you get as much as possible out of each spin. (This is highly debateable and dependent upon other factors)

    6. Build your NEMA plates and shaft coupling so upgrading to NEMA23s (,25 inch shafts) would be easy. Strongly consider upgrading to NEMA23s and then start looking on eBay for deals. I have bought 7 of them for $2.00 before and routinely buy them for $20-$35 each.

    7. Use only Carbide bits and end mills. HSS is noisy and not even close to the cutting ability of Carbide.

    I'm sure I've forgotten ten things, but this should help.



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    Easy way to get gears off- crush it in a vise and it will pretty much fall off of the shaft. If you want to save the gear you need a gear puller.

    From tapatalk



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