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  1. #1
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    Angry Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Hi all,

    Been lurking here for a little while and ran into a problem that (hopefully) someone can help with.

    I recently bought a Harbor Freight X2 Mini Mill and a CNC conversion kit from CNC Fusion. I believe it was kit #2, or whichever one converted all 3 axes.

    I installed everything, it went pretty smoothly. Got the control board put together to run with Mach3. X and Y axis work like a charm, no binding whatsoever. Both move quickly and quietly. Then comes the Z axis...

    Essentially, the Z axis will jog downwards PERFECTLY. It is smooth, quiet, zero binding issues. HOWEVER, when I jog the mill upwards on the Z axis, it binds horribly. The motor starts grinding, the head starts vibrating, it's a mess. It will sometimes move an inch or so freely before the process repeats.

    I have disassembled and reassembled the Z axis 4 times. I have adjusted the gib each time. I have left the two 5mm fine feed screws out of the ballnut block so I could adjust the angle of the block (if you're familiar with the CNC Fusion kits). I've left the motor mount block screws loose and tried adjusting it from the top. I lubed everything as much as I could to ensure it wasn't a friction problem. No luck.

    Not real sure where to go from here or if anyone might have other suggestions. I'm not sure if it is a problem with my mill or the kit itself. As I grow increasingly agitated each time I have to disassemble and start over, I thought someone with some additional experience might be able to guide me. I have sent an email to CNC Fusion, but it generally takes ages for them to respond.

    Also, I can probably supply a video of the problem if it would be helpful.

    Thanks in advance.

  2. #2
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Is the spring assist arm connected and working? The motor alone cannot lift the Z without it.

  3. #3
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Quote Originally Posted by MidnightKrawler View Post
    Is the spring assist arm connected and working? The motor alone cannot lift the Z without it.
    Not so - a 270 oz / inch stepper happily raises my X2 head, spindle and motor - 20 odd seconds from bottom to top.

    The Fusion kit is pretty well made but the X2's quality control can be quite variable - mine maybe is ok as the 1st fit up worked ok but a small reposition would cause minor binding - patient re-alignment with the brackets barely tightened got back to no bind operation - slowly tighten screws a little at a time whilst traversing up and down seems the best way. Good luck!

  4. #4
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Hmm. Out of shear frustration I walked away from it after posting. I was under the impression the 270oz motors would pull the head up on their own and didn’t read anything about reinstalling the spring assist while I put it together... since then, I’ve read of multiple people having success with the motor alone, but also many people putting a counterweight over the top or using the spring assist.

    I highly doubted it was an issue with the kit itself since the mills seem to have many small manufacturing variations. I’m going to reinstall the spring assist and hopefully that will cure the problem.

    I’ll keep you guys posted on the results. Thank you for the suggestions.

  5. #5
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    I use the air spring that came with my 3990. Whether it really needs it or not, I cannot see why you wouldn't use some assist.

    My ballscrews from Fusion are not as smooth as I wish, but I found them to be tremendously BETTER once I coated the screw with way oil I had handy. It came with only a light coat of WD-40. It really needs a better lube.

    I'm curious what others use for grease/oil.

    I'm also sorry you got the Fusion CNC kit. I am (sorry i got the kit myself) and I will repeatedly not recommend others to buy from them.

  6. #6
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Well I reinstalled the spring assist... maybe, slightly helped. Still significant binding when moving the head up. I did, however, notice what I think could be causing some issues. The gib does not seat properly between the head and the column. I pulled the gib out and the top two indentations are way out of line. When placing the gib back in and tightening the screws, the top of the gib is pulled back away from the column- i.e. doesn't touch the flat. While the bottom of the gib doesn't rest against the dovetail at all, but rests against the flat. I can actually put my hand on the spindle motor and feel the head rock slightly when I push and pull on it. My guess is that the gib not seating properly is causing the binding. When jogging the head upwards, if I take my hand and put slight lifting pressure on the front of the head, absolutely no binding occurs. I assume this is because the pressure straightens out the gib a bit and releases the tension on the ball nut. I have sent out an email to Harbor Freight to get a replacement gib. Does anyone know of a better place to buy replacement gibs for these things?

  7. #7
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Quote Originally Posted by tyson77 View Post
    I'm curious what others use for grease/oil.
    I have read that way oil is the best thing you can use. I'm also a complete noob so I have no experience to back that up.

  8. #8
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Quote Originally Posted by KYx View Post
    I have read that way oil is the best thing you can use. I'm also a complete noob so I have no experience to back that up.
    Nothing wrong with way oil - personally I use anything that isn't too thick - anything from 3 in 1 to 10w40 motor oil ,,,,,,,,,,,,,and use plenty. I also run the screw in an old cycle tyre tube zip tied to the ball nut - keps oil in and debris out / off screw.
    Re the spring assist - may help going up but does add pressure coming down! Counterweights best idea though - have a totally neutral weight head to give motor least work!
    The gibs are best described as agricultural and if from Grizzly or Harbour Freight then expect them to be same / little better / little worse - its a crap shoot what you get! Lots of peeps have remade their own using Brass - Hoss did a video I believe check that out for ideas?

  9. #9
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    Re: Z Axis Binding Headache! Harbor Freight X2 and CNC Fusion Kit

    Check with Little Machine Shop for the gibs, I have a LMS 3990, not expensive, but you have to put in
    your own holes or indentations.. I used a 4mm end mill in a v-block, lucky to have a second
    mill. My Z axis gib was also slipping, now the indentations are square bottomed.

    https://littlemachineshop.com/

    I use way oil and regular zerk grease fittings, but the gun has to an 'Oil Gun', I put in
    extra 6mm holes for the fittings, and also Oil grooves.

    Larry
    Attached Thumbnails Attached Thumbnails 100_3648.jpg   100_3668.jpg   Gib Order.jpg   Way  Oil.jpg  

  10. #10
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    Fignoggle has a very good write up about making his own gibs.

    I hadn't realized you can just buy new ones, makes it more convenient to modify gibs if I don't have a second mill available.

    What I've found to be the problem on my 3990 is that the holes in the cross slide don't line up with the notches on the gibs. This leads to binding issues, and poor adjustment.

    I tried using 5mm ball bearings in between the set screw and gib to provide better point contact, but the holes position is so off on one of my x gibs it locks up. Required me to tear it down again. Was very frustrating when I was installing my x leadscrew while converting my 3990.

    I think removing two of the three notches, and leaving only 1 to keep the gib in place is ideal and fully constrained.

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