Wow, Alex... I'm glad you found a mill you're happy with, but in comparing the 3102 with the SX3, I arrived at the exact opposite conclusion. The 3102 has not much more capability (in some cases, much less) for a WHOLE LOT more money (nearly a thousand dollars more!)
I was confused about the price because I couldn't find the SX3 on Grizzly's site this morning. At Harbor Freight (I know the machines are likely lower quality than the Grizzly ones even if they come from the same factory) the price difference was only $400. That is because Grizzly has a much higher markup on the 6x26 than the SX3.
Before deciding to purchase the G0619 (Seig SX3) mill, I did consider the 3102, but it fell short in so many important respects that there was no way I could justify the huge difference in price. I think a lot of potential buyers fall into the trap of thinking that the 3102, since it more closely resembles the ubiquitous Bridgeport-style floor mill in form, is going to have greater capacity than a bench mill. On the other hand, the SX3 mill has the same form as bench mills of much less capacity, and thus it's size tends to be visually underestimated. I was quite surprised at how large the SX3 mill actually is once I got it in the shop.
I think it depends on how you think about capacity. You are talking about the work envelope, where the machines are fairly similar and in some ways the SX3 surpasses the 6x26. The main one is maximum height of the quill over the table, but that is easy to fix. There are dozens of plans out there for building a column extension, and it is a pretty easy milling or lathe project.
I was thinking about the types of operations that I could do on the machine. I build bicycles as a hobby and one of the most attractive things about the G3102 is that I can use it for mitering bicycle tubing with a hole saw. This is a task where rigidity matters a lot (I've done some on my SB9A, it can be borderline for this task) and the extra mass of the 6x26 is a big deal there. I don't think that the SX3 or any of the table top mills would do the job so well.
I'm curious why having such a large swing is important on a mill. What milling tools do you use that fit in an 18" swing, but not an 11" swing?
The 3102 has a range of 7 speeds from 240-2760 RPM, which are changed by lifting the belt cover, loosening the belt tension, shifting the belts on the pullies, re-tightening the belt tension, and lowering the cover, while the SX3 has a (more useful, IMHO) speed range from 100-1800 RPM, selectable in 10 RPM increments by the touch of a button. The motor can also be instantly reversed at any speed, and there is a digital tachometer included. Also, the SX3 has a tapping feature whereby the spindle can be reversed by simply pressing one of the buttons at the end of the 3 spindle feed handles.
Having owned a X2 mill and a 7x12 lathe I'm pretty familiar with the DC motors that give you infinite speeds quickly and easily. I think this is great on paper, but I didn't like it in concept because at low speeds you also get lower torque. With a motor and belt system you get higher torque at lower speeds. On my SB9A I had been dreaming of big DC motors and treadmill speed controllers until I got the thing home and realized that 12 finite speeds really worked pretty well.
As with any tools I think you need to consider how you'll be using it and what the limitations are that you are willing to accept. For my needs I think the G3102 (6x26) makes a lot more sense. Getting one used for little more than a SX3 new made it a trivial decision.
alex
