The X axis DRO scale would prove to be the most challenging part of this DRO installation as I wanted to ensure I didn't lose any of the mill's Y axis movement. This meant the scale would have to be installed at the front of the mill table. For extra difficulty, I also wanted to have adjustable X axis hard stops and working power feed limits. All these features would have to fit in a relatively small amount of space.
Construction continues on the PM Research Number 2 Steam engine so make sure to check out Part 1 of this build if you haven't already. It's time to go back to the lathe and experiment with using CA adhesive aka Crazy Glue for holding small parts. The CA glue is used to temporary hold parts to a scrap aluminum round and is easily released with heat or a soak in acetone.
After building Mr Pete's wobbler from bar stock, I felt confident enough to tackle a casting kit from PM Research: the entry-level Steam Engine #2. Since this engine is basically the same design as the other wobbler, the challenge with this build will be dealing with castings which can sometimes be tricky to machine. Also, you only get one shot making a part so if you screw it up, you will have to order a replacement from the manufacturer.
For a mill, the DRO Z axis configuration seems to come in a few flavors. Some installations attach the scale to the quill, while others measure the movement of the knee. Some complicated setups can use scales on both the quill and knee at the same time so that the final Z axis number displayed on the controller is a combination of both scales. For this Grizzly G0678 mill, I will use one scale to measure the knee movement.
Collets are a valuable piece of tooling for any lathe. With less run-out than a typical scroll chuck, they firmly grip the work without marring while being contained in a small, streamlined package. In this article I will describe constructing my first collet chuck which was machined from a single piece of bar stock. This chuck, which uses ER32 spring collets, will screw onto the spindle of the lathe in comparison to this lathe's native 6K collets which seat directly inside the spindle with a draw bar.
When you are installing DRO scales, they must be placed so that they are working within the same plane as what they are measuring. The instructions provided with the scales state they must be parallel and perpendicular to the machine slide movement within 0.1mm (.004"). Unfortunately, most of the cast surfaces of the mill are not square to the machined surfaces, mostly due to pattern draft. We will have to install square surfaces onto the mill for scale attachment points.
A DRO is probably one of the most important upgrades you can make to a manual mill. By removing concerns with screw backlash or losing count of hand wheel rotations, the DRO allows you to work faster with less chance of user error. Even compared to a new mill, the linear scales of a DRO system are much more accurate than typical mill lead screws. Add in a few advanced features such as center function, bolt circle function and the ability to easily switch from metric to imperial units and it's easy to see why a DRO system is such a popular upgrade.
The Grizzly G0678 mill has been a good mill, but from the very first day of ownership the oil lines have always had a slow leak. After the mill sat for a week or so, one side of the oil system would always drain down into the drip pan so it would take several pumps from the oiler to get the system full and flowing again. The DRO installation was coming, so it was time to get this annoyance fixed.
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.
For several years I've been using a LED work light bought at the local home improvement center for machinery lighting. The promise of LED lighting is a bright, low wattage illumination source that will last a long time. While this light did great on the first two items, it didn't nearly have the promised lifespan. I could just replace the light with a new one, but then I would have to adapt the custom mounting bracket for a different light, so it's easier (and cheaper) to repair the old one.