While the handwheels on the Grizzly G0678 mill are large and of a decent quality metal construction, I wasn't very happy with the stock axis lock handles or dial lock thumbscrews. For the DRO installation, the lock handles for the X axis would have to be changed anyway so it was a good time to upgrade the knob hardware to something that's a bit nicer to use for all the lathe axes.
This mill has some nice dials that are large and easy to read. The dial lock thumbscrews, however, are just cheesy plastic. I purchased some nice Stainless M5x.8 thumbscrews and modified them to fit.
The new, modified thumb screws are on the left while the stock screws are on the right. Brass dog points were installed in the new screws so they don't mar the inside piece they tighten against. For some reason, Asian manufacturers don't see the value in this.
The thumb screws were modified with the lathe. A hacksaw cut them to length and a center drill was used to create the opening for the brass piece which was then held in place with red Loctite. A quick chamfer of the brass dog point and it's done.
The new thumbscrew installed in one of the dials. You could use a slitting saw to add a slot for tightening with a screw driver, but so far I haven't needed to have the thumbscrews that tight.
The stock Z and Y axis lock handles were adequate, but it's possible to install something much nicer. Two identical handles were purchased from McMaster-Carr, part number #6271K69 labeled as: Zinc Adjustable-Position handle, 3/8"-16 Threaded 1 9/16" Long Stud, 2 5/8" Projection, Black. Here you can seem them installed with the axes unlocked.
The beauty of these handles is that they have a spring-loaded spline so you can lift the handle and rotate it freely while turning the stud with a screw driver. This way you can clock the handle perfectly for the closed or locked position.
Here the axes were locked with just a partial turn of the handles. Even though there is little room, it's still easy to use the axis locks as the handles fully tighten at just the right location. Also, the larger handle size really helps lock the axis down with minimal effort.
For the money, this was a great upgrade, but don't throw the old handles away yet because they will be modified for the X axis.
The original X axis lock handles were small and difficult to tighten firmly so they went into the trash. The just liberated Y and Z axis lock handles will be used for this purpose. The old threads were removed and new extensions were made on the lathe.
Everything was Loctite'd and pinned together. I also added brass dog points, which is probably overkill for this purpose. The handles were also shortened a tiny bit as they were hitting the ways.
Here the new handles have been installed. The extensions were needed to clear the X axis DRO scale. Like the other axes, it's now much easier to firmly apply the axis lock with the longer handles.
These may seem like slight improvements, but on a small mill like this it's important to use the axis locks whenever possible for maximum rigidity. If the locks are easy to engage, it's more likely they will actually be used.