I’ve had my Longmill 30 for a year and suffice to say I am less than impressed with how this year has been.
When I got my Longmill I was excited to start learning how to use it and cutting. I assumed I would break some endmills here and there but I’ve broken more than I’ve expected and I don’t think I am really know what is wrong with what I am doing. I compare my machine to how other people run their routers, or how I’d even run my own hand router and nothing seems to work! The only things I have been able to make have been with me 1" surfacing bit using it with adaptive clearing to make a tool for work which was just a circle with a ring on top, and an Ohio flag with 2mm grooves for a friend. Cutting out the contour was a pain and had to be done in 2mm passes as well at 40 IPM.
So the start of my problems: I put everything together and the Y axis had grinding noises and would stop up on its rapids. After adjusting the backlash nuts and ending up replacing the whole bolt that came with it because it caused clearance issues with the Y travel at the end I solved the problem. It was because the backlash nut was to tight to the gantry - not the lead screw.
Afterwards countless hours ensued trying to level the gantries out. The V Wheel with eccentric nut system seems all nice, but even on a level surface that mine was mounted to the eccentric nuts just don’t allow enough travel to have everything evenly clamped. I’ve gotten it the best it can be, but it’s just not a good system in my opinion. Furthermore the V Wheels on the XZ axis carriage is a massive rigidity problem, as when cutting forces are applied it equals leverage to the whole XZ axis. The V-Wheels are not a rigid way to mount the Z axis at all, and I notice mine easily flexes just by pushing on it with one finger without even having a spindle mounted - worse when the spindle is mounted. 0/10 if anything in this system needs to be put on linear rails it’s the XZ axis. I’ve tried tightening the wheels, it only adjusts for so much before it will cause too much force to move the axis at all.
The Z Axis motor is underpowered for any spindle that is not the Makita router, and the mounting bracket is just bad. Only 2 points of contact to mount on a thin bracket. It flexes by sneezing on it. I had to modify my Z plate to fit a thicker spindle mount with 4 bolt holes in both X and Z directions because my spindle would just flex.
Squaring the spindle is an absolute nightmare. Spent forever trying to get mine square enough to use to surface anything. You can pretty much forget about it when it comes to the spindle bracket that comes with the machine. You can shim for adjustments needing made in the Y axis but when it comes to the X axis you’re just out of luck unless you enlarge the mounting holes. This would be a system that would benefit so much from an eccentric nut, or a set screw that would raise / lower the bracket on one side. The only way to do it now is to adjust the V wheels on the axis rails which changes the clamping force and leveling of everything else and it’s just a miserable experience. I fixed with the modification to mount the other spindle bracket and oversized the holes slightly to allow for alignment.
Some of my problems come from having a heavier spindle on it - but the core of the problem comes from the lack of rigidity in the XZ axis.
Moving on to now. I have it working well enough despite the Z axis not being able to make accurate movements. I’ve spent dozens of hours trying to just get good chips with a the 1/8" 2 flute endmills I have.
I just can’t get them to work.
Using the recommended settings from the wiki snapped my end mills and started fires.
I’ve tried running it at so many RPM ranges and feed rates that I can’t even remember. None of them work “well” unless I am taking basically a depth of cut that doesn’t mean anything. Any time I try and do a depth of cut that is larger than 2mm it will just either burn or break the endmill, flex the axis, etc.
No matter what RPM there is and feed rate.
I’ve tried mainly working with pine and I cannot get this to work for anything.
Pictures of the spindle bracket modification with the spindle: