Pros: Willing to take on difficult jobs, good cutting capacity, flexibility, quiet operation.
Cons: Difficult to move, maintenance required, Difficulty of leveling.
The Grizzly G0619 is a mid-sized home milling machine imported from China. Unlike the common smaller "Mini" mills, this unit has more power and a heavier duty chassis which gives it more ability to take on larger sized projects. More importantly, it is large enough to use a power feed, which takes it from being toy-like to being able to produce the regular perfect cuts of a professional machine shop. This is a very large piece of equipment for an individual to deal with at 400 lbs, but the return is a large working envelope, precise power, and the ability to handle the majority of cutting tools.
Small milling machines are an answer for people who don't have the space, funds, or the continuing need to deal with a 2000+ lb. full-sized knee mill. The market for small mills has been somewhat strange, though, with a lot of products on extremely small scales which sacrifice much of their capability for small size and low price.
Some of the most famous very small mills have been made in the US by Sherline. These machines are extremely small; to the point where one could pick up the entire mill and its drive assembly by hand and the machining head is approximately the size of a Dremel tool. While this is sufficient for small model parts, this isn't a practical solution for someone who wants to make large objects out of 1" thick aluminum plate.
I wanted to be able to make my own components for telescope mounts, repair parts for things as needed, and other projects as they came up. And I knew I would need to be able to cut aluminum, steel, and other materials to precise shapes with dimensions up to 15". That just isn't a job for a really small machine.
Many mill-drill combinations have some crippling faults ranging from gear drives prone to breaking in the event of sudden tool stoppage to cylindrical columns which cause the cutter to drift left and right every time they are moved up or down.
In doing research, the Grizzy G0619 stood out for several reasons:
-Dovetail column (so the head would stay centered when moved)
-Compatibility with power feed
-Digital speed control
-Digital quill height indicator
Of course, this came at a price, and $1250 is nothing to sneeze at. That doesn't include shipping, which took the price of the mill to just under $1400. But, the next size up or down came with a major sacrifice in the available features.
Description and Assembly
The G0619 was shipped via UPS's heavy freight service. Unfortunately, the first attempt at delivery resulted in an exercise treadmill showing up. The driver took it back, and on his own initiative returned with the machine from the warehouse that evening (Well done, UPS Freight!). The wood crate was slightly smaller than a washing machine, and at over 400 lbs needed both of us to pull the fork dolly around to my workshop. By the time we got it in the door and set it down, the crate was starting to come apart; it had taken the machine as far as it was going to go.
In the crate the machine was covered with red grease to prevent corrosion in transit. The package of materials with it had the wrenches for the drawbar, a pair of hold down clamps on the table, and a set of allen wrenches for its own adjustments. The red grease comes off with mineral spirits and a bit of work. I found painting surfaces with mineral spirits, first, would dissolve the grease so it could come off with a shop rag. The photos of the machine do not show the color of the paint correctly; it is a deeper metallic green, closer to a pine green than the mint color in the photos. The machine is physically large compared to Mini-mills, such as the one from www.micromark.com. The tall dovetail column is its most visible feature, standing well above the table. But this is what gives it an unusually large machining volume, where much larger machines weighing over 1000 lbs add fractions of an inch between the head and worktable compared to the G0619.
I had a welded steel table to set the machine up on. I rented a disassembled engine hoist from the local equipment rental place and bought a 2000 lb capacity 6' strap at harbor freight. I wrapped the strap around the head, undogged the machine from the crate floor, and with my wife operating the hydraulic jack on the engine hoist, lifted it free. This turned out to be an easy way to get the machine positioned since I was able to nudge it to exactly where I wanted it to be, and could always lift up on it again to adjust until it got there.
I took apart the lift and returned it, to which the rental folks said, "You're done already?! it's only been three hours." I answered, "I had a plan."
The next step was getting the X-axis power drive installed. This requires taking the left end of the work table apart to attach the power feed to it. This is fairly easy to do, but is a lesson in how every single component of this machine is heavy. The power feed comes with a limit switch with two stops to put on the front of the machine table to automatically turn it off at the ends of its travel.
The break-in for the machine has a prescribed time to run the drive, which turned out to be surprisingly quiet. And before I knew it, I was ready to start milling.
The machining head is compact and fully enclosed. Opening the top shows the motor pulley goes straight to the drive spindle without any intermediate gears. The entire head rotates to the right up to 90° to allow it to do horizontal machining. In practice, I've found getting the head leveled for conventional vertical machining is enough trouble to make the idea of breaking the setup to do this to seem like a limited benefit.
Operation is quite simple. The machine beeps when powered on, and when mode buttons are pressed. The default speed at startup is 100 RPM, and holding down the increase button allows it to be adjusted in 10 RPM increments. The drive remembers the last setting it was in, so after stopping, it returns to the last speed and direction it was running in.
The drive is reversible, and if it is in the Tapping mode, will reverse when one of the green buttons on the end of the quill down-feed handle is pressed, though with some delay. The drive is quiet in all modes of operation, and will not interfere with regular conversation volume levels.
There is a guard on the front made of clear plastic, which swings across the front of the cutter. While this is nominally a safety feature, I found I kept driving it into common work setups it dragging on hold down clamps on one hand, while on the other it is too short to actually stop chips from being ejected out the front. I threfore took the extraordinary step of removing the guard (the switch is in a housing on the left side- if the shaft the guard rotates on is removed, the switch is left in the "Closed" mode), since it appeared to be a hazard rather than a safety feature.
All of the bearings for the axes on the machine have oiler balls on them, and each machining session starts with oiling these. What is not indicated in the manual is the dovetails on the table have to be manually oiled. This makes a big difference in the smoothness of the drive, so I strongly recommend carefully moving the table side to side, removing the existing oil and grit, and then re-oiling it with a corrosion inhibiting machine oil, such as 3-in-one oil. Every time the tables get to where they expose part of the ways, I replenish the oil with a few drops, and the action stays smooth.
Operations and Usage
For conventional milling, the G0619 is capable of taking cuts up to about 0.050" per pass with a 0.75" cutter. Going deeper in this causes lagging in the table drive due to loading. But one very nice feature is the machine is very forgiving with automatic features to stop the drive if it encounters too much resistance (very good for beginners).
One of the most useful operations for machining is simply making holes. The G0619 has ample power, but also its digital readout on the quill position as well as a precision down feed make reaching a specific hole depth very easy. For special types of holes, such as recesses for cap head screws, the ability to slowly drive the quill with a hand feed means being able to reach a depth within 0.0005" of an inch. Where using the crank for raising the head would be significantly more difficult, the precision feed and digital readout make your current height above the reference zero point completely unambiguous.
However, with repeated use, the drive speed slowly creeps up. So , for example if drilling a pattern of holes, the 5th or 6th hole will have seen the drive speed up by 10-20 rpm above the original set point. This happens faster if the bit is loaded and unloaded to clear chips out of the hole. But since it only takes a tap on the speed reduction button to correct, I don't see this as a serious problem.
Fly cutting is important for being able to take uniform thin layers of metal off of a workpiece. Not only does this allow removal of a gouged or discolored surface, but it also looks nice on the finished part. I have ended up fly cutting several different ways, with varied results. First, keep in mind the rotational speeds for fly cutting are much slower than for small milling cutters. The second issue is the head has to be absolutely perfectly perpendicular to the worktable to get a flat cut. A good alignment can be recognized by both sides of a 2.5" cutter making contact on a fly cut so the fine grooves form a Moire pattern in the surface.
I have settled on doing most of my fly cuts using an R8 sized fly cutting tool holder with an AL-6 brazed carbide cutter at 300 RPM. This produces good results in cuts up to .005" per pass. I have also used a smaller AL-5 cutter in a small fly cutting attachment made for .5" collets with good results. The main issues I have found is the table tilts slightly when driven all the way forward. While this isn't an issue for regular milling cuts, it causes fly cuts on a large surface to have periodic edges in them. It is better to leave the table at one Y position and reposition the workpiece on it to get a uniform cut.
I have also used the Grizzly G2861 fly cutter, which has four carbide bits, and therefore a lower force per bit. However, given the excellent performance of a conventional fly cutter, this has turned out to be unnecessary, though it works best for small workpieces where I can hit the entire surface in one pass.
The tapping feature on the G0619 is supposed to enable the mill to take a tap, drive it in, and then reverse at the push of a button. In practice, the mill does go into a special tapping mode at the push of a button, but the speed can still be set to whatever you like, though it should always be slow for tapping. The ends of the arms on the down feed have green buttons which trigger the machine to reverse. But the forward inertia of the machine causes it to keep moving for a moment before it reverses. So if you are trying to reverse the tap periodically to clear the chips, it won't work well. In practice, I have had enough experiences with badly threaded holes that I use a hand tap instead of this feature (but I do crank the head up so I can use the quill to center my tap on the hole and keep it vertical).
What happens when things go wrong is one of the best indications of a machine's robustness. In general, the G0619 protects you and itself in common mishaps, and that makes it a very good starter machine. Here are some of the mistakes I made with the response of the machine:
Hitting a clamp with the fly cutter and stopping the tool: The machine attempted to drive for a moment, then automatically stopped the head, beeped, and displayed "ERR" on the readout a moment, then automatically reset itself and was undamaged.
Running the X axis of the table into the end of the track while under power feed: The drive attempted to move for a moment, then stopped and displayed a yellow fault light.
Loose Gib on the X axis- the only symptom was the table became somewhat jerky at low speeds because the table was getting cocked to one side. Holding on to one end of the table and rocking it back and forth showed movement. Gently tightening the four gib screws and testing for movement fixed this.
The G0619 is a potent and flexible machine for a small shop. While its price seems high compared to the bottom tier of mini-mills, its vastly improved capacity, controllable operation, and willingness to take on large projects is worth the price. My one complaint is if one wants to go to a larger machine than the G0619, its superb features are not all available in a larger machine.