Has anyone found an easy way to switch the router mount from the upper set of holes to the lower set of holes on an assembled machine without taking too much apart or requiring large amounts of subsequent adjustments?
Looking at it, I think backing out the lower pair of screws that hold the Z rails and removing the lower bolt holding the dust shoe bracket might allow me to slide the Z axis down to the point where I could access the bolts that hold the router mount.
And if I might make a suggestion for future releases of the Longmill, perhaps hex head bolts could be used to secure the router mount so the position could be swapped with just a crescent wrench.
I went ahead and tried removing the magnetic dust shoe bracket and backing out the lowest set of bolts holding the Z rails. I also had to back out the two bolts holding the Delrin block for the Z axis as they stick out the back and interfered with the X gantry when the Z carriage is below it’s normal range of travel.
I then turned the Z axis threaded rod to lower the Z axis. The Z axis was just about low enough to reach the router mount bolts when the linear bearings slipped off the rails. Which wouldn’t have been a problem had it not be accompanied by an ominous “plink” quickly followed by another “plink”.
That was the sound of two microscopic ball bearings falling out of the linear bearing assemblies. It was only then that I realized there was a good reason that part of the router came preassembled. (Funny how so many of my shop stories include the phrase “It was only then that I realized…”)
Happily the bearings fell into divots in my spoil board rather than disappearing on the shop floor.
While the Z axis was off, it was no problem to move the router mount to the lower set of holes.
I put them ball bearings back into their ball race using needle nose pliers, and then I attached small magnets to the left and right sides of each linear bearing to help keep the ball bearings in place until I could slide the linear bearings back on the rails.
I reversed the remaining steps and everything worked out in the end, but if anyone has a better way of lowering the router mount, it would probably be a good idea to post it for everyone’s benefit.
Yeah, it is a general remark: You should never remove the carriage from its rail!
Few weeks ago, I removed the Z-plate by unbolting it from the delrin block and the Z- carriages. Then I had free access to the screws holding the mounting block.
Why you want to use the lower configuration?
I just switched back to the upper holes as I couldnt screw the mounting block perpendicular onto the z-plate using the lower holes… even after sanding the surface of the z-plate and the back of the mounting block, I wasn’t able to.
So what I want to say: check for the squarness of z-plate and mounting block when reassembling them.
Thanks for the tip Jannik. Sorry to hear you had trouble with your mounting block. I checked the router mount and fortunately mine is still perpendicular to the Z carriage.
I need to use the lower configuration because I’m milling 6mm Baltic birch plywood with a relatively short bit. I tried using a longer bit but I had one break on me, so I’m trying the shorter bit in the hope that they’ll be more robust.