Cheating the Z axis

I bought a 65mm 110v 1.5kw chinese spindle and vfd a while back and have it all working properly, with the VFD triggering an external relay to run my vac and coolant when the spindle is on. Pretty happy with what it is for what I paid, but I haven’t cut anything with it yet and it was much more expensive than a trim router. Anyway, I just received my woodworker and set it up far enough to realize how tall this spindle is. It says 200mm but it’s really 250mm from the top cover to the bottom of the collet nut.

I’m not crazy about the “excessive” distance between the spindle clamp and the end of my bit, but I’ll have to see if it causes much deflection. If I clamp the spindle any lower, the top of it hits the bottom of the z axis motor before the slider can get all the way to the top where it would home. I’m wondering if I could just let it stall home when the spindle and z axis motor touch, although I doubt this is a desirable thing to do. Another option would be to make some type of “homing block” to avoid using the spindle as a stopper. It would need to be used every time the machine homes, or possibly permanent. A couple of 2 piece bolt together sleeves around the top of the z axis linear bearings, equal in length, would be my idea. I would bottom out my z axis with my surfacing bit 1/2” deep into my wasteboard, and still clear a 2 1/2” thick piece of material with a 1 1/2” flute length bit seated to the top of the flutes. The reduction of bit to spindle clamp distance would be significant, maybe 65%. I also understand that there would be a danger zone in the lowest part of the machines z axis travel where the theoretical limits exceed the physical limits of the z axis… and opportunity for other harmful screw ups, but this is long enough. Is there anything beyond common sense that would prevent me from achieving that?

Are you on the lowest set of holes?

I am on the highest set of holes, but the z axis motor is fixed to the z slider, so the distance from the spindle clamp to the z motor remains the same regardless of which set of mounting holes you use

I think your idea of a stop block for z homing has merit, and certainly a better option than using the collision between the spindle & z motor. I’m also thinking you could tweak the controller z axis settings to adjust total travel accordingly.

As I look at your setup (btw, LOVE the brick!) I can’t help but wonder if you could benefit from purchasing another spindle clamp block from 1F (if they would sell you one), and stacking them, essentially doubling the spindle support. The bearings are 2.75" long, and the spindle clamp block is 1.5" thick so there’s an opportunity to gain extra support. Doing that would certainly change how the z axis stalls for home, and you may even lose more top-end travel.

Thanks Bill! I was hoping to get a reply from you. I had considered that there may be some settings that could be adjusted somewhere, but haven’t really delved into the controller just yet. I like the double clamp idea and was thinking about a second spindle clamp on a separate set of guide bearings of reduced length. May need to look into it as that sounds fairly straightforward if I can get the spindle clamp without buying a whole new z slider.

I might look into raising the stepper up so it doesn’t hit and you can still have the full travel of the Z axis (if that’s important to you). Otherwise the fixed block idea should work but I think you’ll have to change the Z axis setting or you’ll risk it bottoming out if it tries to go to far down. I guess it really comes down to how much Z axis range do you need/ want.

I’ve sourced some new linear guide bearings for the z slider that are the same overall height as the spindle clamp, and contacted onefinity to try to purchase an additional spindle clamp. If I can mount another clamp to the z slider to hold the lower 1/3 of my spindle then I’ll be satisfied with the fix and won’t need any special homing blocks or procedures.

1 Like

Now you have me worried about mine. I will have to make some measurements and watch closely as to how you solve this challenge,

Thank you for posting this.

It’s probably not really an issue. I’ve only made a couple of cuts with my machine, some 61mm holes through 3/4” plywood with 1/8” clear acrylic on the bottom of it. Spiraling plunge at 90 inches per minute, 1/4” upcut bit at 80% depth of cut. The holes are perfect and the machine had no problems cutting at that speed, so at this point I’m not particularly concerned about it. Although adding the second clamp is still something I’d like to do, just out of principle.

1 Like