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Thread: Convert a Grizzly G0781 to a CNC mill

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    Default Convert a Grizzly G0781 to a CNC mill

    Hello all,

    New member for this forum. I recently purchased a Grizzly G0781 mini mill and would like to convert it to a CNC mill. I have never done this before but have some automation experience in a past job so I though I would give it a try. I would love to get opinions on my path forward.

    The first thing I will need to to is to convert to ball screws I initially start with ball screws and hand cranks, then convert to motors, depending on overall cost and recommendations on parts.

    Ball screws - I'm thinking C7, cheap china made would be a good start. I have read that it's a cheap way to go and the ball screw may not last, but initially, it seem like a good path. I feel I can convert to better made screws if they wear or have an inconsistent backlash that can't be compensated for. The ball screws will be much better than the current lead screws installed. Amazon has a selection for $50-$70 per axis, including end supports.

    Brackets for the ball screws - I'll need to fab up simple brackets to mount the ball screws with the current setup. I think I can make simple brackets that only need single axis movement cuts so I can make the brackets with the current lead screw mill setup.

    Option 1- Motor controller kit 3-Axis NEMA23 CNC Kit (48V/7.3A/425oz-in/KL-5056). from Automationtechnologiesnc.com. Motors, drivers, and power supply. A good cheap option. $280.

    Option 2 - piece together.
    Motion Controller - Gecko drive, G540, currently selling the pumpkin spice edition. This is the controller and the motor drivers.$270.
    Motor - STP-MTR-23079 from automation direct, $40 each.

    Software
    AutoCAD Fusion 360 for design work
    Mach3 (or Mach4) for CNC control. Demo initially, then convert to paid if I start making money cutting other peoples parts.

    So, that's the plan. Tell me what you think and where I may have made poor assumptions. Tell me if you have experience with any of these or if you have recommendations I should look into.

    Thanks for your time,
    Flagstaff

    Similar Threads:
    Last edited by Flagstaff; 10-27-2020 at 12:37 AM. Reason: Removed an old motor option I was looking at.


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    Default Re: Convert a Grizzly G0781 to a CNC mill

    Your post covers a lot of ground so I'll just post some random thoughts.
    That mill appears to be a variant (near copy) of the Sieg X2 mini-mill ? If I'm wrong about that the rest of this post won't make much sense
    A search for member Hoss2006 will find much info on converting these mills including a mega-thread. His website is mostly dead links but it's archived near complete.
    Link --> https://web.archive.org/web/20161014...onversion.html

    Automationtechnoligiesinc has a bolt-on conversion kit but I suspect you're trying to avoid that type of expense. It really is kind of pricey.

    I have C7 ball screws on my mini-mill and they're still fine after many years of occasional use. The large flanged type ball nuts commonly listed for sale are too big to fit under a mini-mill table. Or better said they're too large for the style of conversion I've done, maybe you have something else in mind. Chinese suppliers will machine a ball screw to your specs but they all seem to be selling the same large flange ball nuts.

    Manual machining with ball screws is doable but not the best. The table locks help here.

    I use Geckos but there's better bang for your buck available made in China. Hopefully others weigh in on that topic.

    Mach3 is nearly abandonware, go with something in active development like uccnc or mach4 or linuxcnc.
    Fusion 360 is great if you're willing to put in the time to learn. If you don't trust Autodesk (and I don't) FreeCad is another option but honestly Fusion is easier to learn.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Convert a Grizzly G0781 to a CNC mill

    Quote Originally Posted by cyclestart View Post
    Your post covers a lot of ground so I'll just post some random thoughts.
    That mill appears to be a variant (near copy) of the Sieg X2 mini-mill ? If I'm wrong about that the rest of this post won't make much sense
    A search for member Hoss2006 will find much info on converting these mills including a mega-thread. His website is mostly dead links but it's archived near complete.
    Link --> https://web.archive.org/web/20161014...onversion.html

    Automationtechnoligiesinc has a bolt-on conversion kit but I suspect you're trying to avoid that type of expense. It really is kind of pricey.

    I have C7 ball screws on my mini-mill and they're still fine after many years of occasional use. The large flanged type ball nuts commonly listed for sale are too big to fit under a mini-mill table. Or better said they're too large for the style of conversion I've done, maybe you have something else in mind. Chinese suppliers will machine a ball screw to your specs but they all seem to be selling the same large flange ball nuts.

    Manual machining with ball screws is doable but not the best. The table locks help here.

    I use Geckos but there's better bang for your buck available made in China. Hopefully others weigh in on that topic.

    Mach3 is nearly abandonware, go with something in active development like uccnc or mach4 or linuxcnc.
    Fusion 360 is great if you're willing to put in the time to learn. If you don't trust Autodesk (and I don't) FreeCad is another option but honestly Fusion is easier to learn.
    CycleStart
    Thanks for your reply. This is exactly what I was hoping for. I will look up Sieg X2.

    I wasn't able to find similar to the Grizzly I bought and have been happy with Grizzly so far. I have had a table saw that has worked very well for 15 years so I guess I'm partial.

    Good to know the C7 ball screw route is a good choice. Makes me feel good to know they should work, provided the ball screw nuts fit.
    I noticed the pitch is quite a bit different and that may be what you are referring to when you say the table locks up.

    I'll look into Mach4 rather than Mach3. Possibly, the others you mentioned. I have developed on a lot of different software and I agree, about not trusting AutoCAD. Dessalt (Solidworks guys) converted their DraftSight to a subscription and I used it for 2D for years. (now using nanoCad). I have also used Sketch-up but that doesn't seem like a good fit here. I'll also look into FreeCAD.

    I'll start to post pictures as things develop but for now it's just the mill, no mods yet.
    Thanks for the insight CycleStart!



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    Default Re: Convert a Grizzly G0781 to a CNC mill

    Quote Originally Posted by Flagstaff View Post
    CycleStart
    I noticed the pitch is quite a bit different and that may be what you are referring to when you say the table locks up.
    Table locks are the little levers that can apply pressure on the gib strips. Your manual may call them by some other name. Unlike the acme screws in your mill a ball screw has very little friction and won't resist rotation when force is applied to the nut. The table locks resist free movement.

    Fusion and FreeCad are both CAD+CAM. Using other software a CAM add-in is needed or a separate CAM software. Don't let my prejudices turn you off Fusion 360, it's CAM capabilities are impressive for something free-to-use.

    One control software I forgot to mention is GRBL. It's simple and free, It usually runs on an Arduino Uno but it's been forked to other hardware as well.

    I was wrong about your mill being an X2 , it's an X2L. Grizzly sells the X2 as a G8689. The kit mentioned in my last post is shown here:
    link --> https://www.heavymetalcnc.com/shop/x...3990-lms-4190/
    that conversion kit is better known under the original company name cncfusion. Note the small ball nuts.

    Good luck with whatever direction this project goes.

    Anyone who says "It only goes together one way" has no imagination.


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    Default Re: Convert a Grizzly G0781 to a CNC mill

    Thanks for the info, again. Heavy metal cnc actually has my grizzly part number for the kit. You have been very helpful. Thanks muchly!

    Unfortunately, the forum makes me go through entering my information and clicking on the email conformation every time I want to post a message and I'm beginning to think the forum has some critical flaws. Although you have been fantastic, the forum is getting frustrating. If I am required to go through the process yet again, I may just give up and stop posting here. It stinks to think you found a great place of people and the admin rules make it a PITA to deal with.



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    Default Re: Convert a Grizzly G0781 to a CNC mill

    Yeah I've also seen weirdness from this website's software. Please don't feel obligated to reply, I don't post here for thanks, mostly it's boredom with my current reality. I got this in my youtube recommendations and thought it might be of some interest. The upside of this conversion is the use of common Chinese screws that can be ordered custom machined for a small amount of money. The obvious downside is the 'butchery' required.


    Anyone who says "It only goes together one way" has no imagination.


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Convert a Grizzly G0781 to a CNC mill