Grizzly G4003 12x36 Lathe Depth Stop Widget and Metric Threading · Dec 31, 10:58
After going through the collet closer vs. 5C collet chuck question, we cut a 3” diameter aluminum blank (we debated on using steel, but thought that having less spinning mass may be advantageous) and chucked it in the G4003.
A few key things to remember about metric threading on this lathe as well as the peculiar non-standard thread of the outboard spindle tube. We knew that the pitch was 1.5mm, but the diameter seemed to range between 40mm and 45mm based on first measurements. We’ll keep the suspense to a minimum. It’s a 42mm x 1.5mm thread on our 12×36 Grizzly-branded G4003. This of course may vary with yours. Who knows, it appears that some things just aren’t standard with Chinese machines and tooling.
Here’s the thread mic’d with the caliper.
Here are some tips when following the chart on the lathe for threading. Since our thread is 1.5mm, we need to replace the “F” and “G” gears AND reverse the idler 91T/86T gear assembly.
The 91T gear is on the outside. We need this on the inside.
We used the arbor press to remove and re-insert the spacer bushing.
For metric threading, DO NOT DISENGAGE the thread lever once engaged. We used the “inch” button for threading into the shoulder and then hand-cranked the remaining bit to the shoulder. We prefer this method over flipping over the bit and threading away from the shoulder. It’s always nice to see what’s happening.
We also had to make sure that the feed levers were in the “B” and “6” position. This, along with the swapping of the idler gear assembly and replacing the “F” and “G” gears allowed for a proper thread.
After a few deep cuts at .010” with the 3/16” square HSS bit we ground by eye (freehanding this is fine with a fishtail gauge), we test-fit the plug:
It fits!
Here’s the plug, it’s a big one:
Next up, a threaded hole and a cross-drilled hole for a handle to allow us to hand-crank the spindle. And of course, plans for this plug.
Comment
Commenting is closed for this article.