The next step was to cut either side of the slider plate with the end mill. I decided to make the plate 1.25” tall so I progressively milled out either side of the plate as seen below.

       The end mill and rotary table combination produced a nice sweeping arc.

       I traversed in the X-axis 1.5” and cut the under side of the slider plate as seen below...

       I cleaned up the edges of the plate and she was ready to go.

       The next step was to drill/mill out the bolt pocket for the locking bolt which will be press fit into the shifting handle. I started out by drilling a 1/4” hole at 5.125” center from the pivot point of the tumbler assembly.

       Next I used a 7/16” end mill to counter bore a .150” deep pocket which will hold the head of a 1” x 1/4-20 stainless steel bolt.

       Using my hydraulic press I seated the 1/4-20 bolt into the pocket as seen below.

       Here is a photo of the bolt after it has been pressed into the pocket (below). This setup worked very well as the bolt is incredibly secure.

       Now that the locking bolt is in place I can lay out the slider plate holes. I marked out the shifter travel  and centered the plate so I could lay out the bolt holes.

       Using a long 17/64” drill bit I was able to drill out both slider plate mounting holes as seen below. The rear hole is a bit harder to get to considering the spindle pulley is partially in the way but I was able to get it in at a slight angle regardless.

       I used some 1/4-20 Allen head bolts and nuts as spacers to mount the slider plate as seen below. The shifter could now move to it’s given limits without binding the gears. Of course I had to fine tune the shifter’s travel by filing the ends of the slider plate slot a bit.

       You can see the tumbler hardware on the inside of the headstock casting. Although the rear slider plate bolt is hidden in this photo.

       To help finish off this build I decided to mark out the different shift settings on the slider plate as seen below. I used a metal stamping kit to mark the different positions. The “L” is for left-hand feed and the “S” is for stop and the “R” is for right-hand feed.

       The last step was to trim the end of the shifting lever to match the slider plate as seen below. I used a needle file to make the shift indicator lines.

       I used a 1/4-20 threaded knob to lock the shifter in place (McMaster-Carr Cat# 3992T29). It is very simple but works very well :0) You will notice that I had to trim off one of the corners of the slider plate to clear the belt/gear change door on the lathe. Easy fix ;0)

       I tested the gears in both directions and the system worked very well. No binding or any excessive noise from the gears at any speed.

       I tested some left-hand cuts with the new tumbler and was super happy with the results. This is a very easy and effective mod for this lathe.

       I have to thank Dennis Atwood again for posting his article and making this mod a snap!!!

       The best part about this build is was that it only cost about $40 in material to complete! Although I am pretty sure that Grizzly will offer the feature on next years model rendering this article useless ;0)

       Before I closed up the shop I decided to make a belt holder for the gear change cover which holds the high or low speed belt as the other belt is being used. Take note Grizzly Industrial ;0)

Added on February 2, 2012:

       After running my lathe for a while I decided to streamline the belt changing process a bit by modifying my belt tensioner. I added a handle to the swivel arm with a piece of angle iron that can be used as a hand lever to put pressure on the change belt while tightening the bolt that holds the arm in position.

       The handle is held in place with the existing bolt and a keeper tab was made on the bottom of the handle to keep it from spinning (seen below). It is simple but works quite well.

       You can see below how the lever arm gives the user leverage to tighten the belt while the other hand can tighten the nut on the tensioner.

       To make the belt change process even easier I purchased a set of longer belts as the metric stock belts provided were a bit too tight (even with the motor/idler adjustments available). I bought two sizes for the high and low end pulleys which are a 3L340 (high) and a 3L290 (low). Now the belts slip over the pulleys much easier making a speed change more convenient.

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