# Preview  -   Grizzly G8689 - 4" x 16" Mini Milling Machine   -  90 Days



## Logan Novice (Jan 7, 2021)

I have had it a bit longer, but the use period is only about 90 days.
On delivery it was found to be so well packed that not even running into the crate with whatever the shipper used did any damage.
Initially VERY noisy; sounded like a screaming banshee.  Service desk arranged for a replacement motor gear and primary gear (PN P868918 & PN 8689138) and with a bit of gear grease and running the break in procedure it quieted down nicely.
Operation was satisfactory except that the Micro Downfeed Control was stiff over most of its rotation.  I was able to fine tune the control by placing a shim (approx. .020) between the downfeed bracket (PN P8689089) and the spindle box then tweeking the downfeed bracket and the support block (PN P8689081) to free up what turned to be a minor bind in their alignment.  All in all a relatively minor issue.
There was one other minor issue I had to deal with; one that puzzled me for a few days.
In raising and lowering the spindle there were a couple of points in the travel where the spindle block would seem to slip; as if it were hanging up and then quickly releasing.  That generated an unexpected drop of the cutting tool by about .025 during some cutting operations so I couldn't trust the downfeed control, and even controlling the spindle with the downfeed handle with confidence got a bit worrisome.  I figured the problem had to be either the pinion or the rack so I tore it down to take a look.
What I found was that the bevel gear (PN 8689052) moved smoothly over some portions along the length of the machined "neck" of the pinion but hung up at about the mid point of travel.  That's precisely where it's supposed to ride and run smoothly.  It was easier to order a new rack and pinion set than mess around with it.
The new parts are different.  The original pinion had two punch marks on the long axis of the "neck".  I suspect it was the raised perimeter of these punch marks that changed the diameter enough to interfere with the smooth movement of the bevel gear.  The replacement pinion had no punch marks.
I also found that the replacement rack was about 13 1/2 inches in length compared to the 8 1/2 inch length of the original.  Even though it really only allows for about an additional 1/2 - 3/4 inch of vertical travel for the spindle, it's a nice bonus.  To install it at its full length it is necessary to remove the  the spacer (PN8689102  -  the position for which is, incidentally, incorrectly depicted in the owner's manual).
Only disappointment was that the replacement rack has four mounting holes where the original had two  -  so I had to find two m6 - x12 screws.  
The machine works extremely well and meets all of my current milling needs.  It supports my rotary table and dividing plates (even with the rotary table tail stock if the part isn't too long) and it runs true on both X & Y axis.  I am very satisfied with this little mill.   I just finished making a part measuring .5 inches in diameter and 1/5 inches in length that has 18 holes evenly spaced holes in six rows over its perimeter and the holes are very accurately positioned.
I applied a dab of paint to mark the side of the head to locate the locking pin notch and, because peripheral vision isn't very good and I sometimes forget to remove the spindle locking pin (PN P8689180) when I restart following collet or end mill change out, I painted the locking pin white.  Makes my life a lot easier.


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