Hi, I have owned the Optimum (TopTech) BF30 for about 1 1/2 years and for the most part it is a very decent mill for its size and cost (if bought from one of the two Canadian dealers). It is a completely different machine then their BF20 (much larger), and all though it shares similarities to the Weiss WMD30LV and Precision Mathew PM-30MV, it is not the same machine/castings/electronics (etc.) from what I was informed. The Optimum BF30 is sold under the TopTech (and others names outside north America) label which is a spinoff from the company that makes the BF30 for Optimum. It is identical as far as I can tell, they even use the exact same manual and parts listing.
The overall fit and finish is good, and accuracy/reproducibility is also good, but it is still made in China, and despite being under "German" supervision, I doubt they had any influence on the basic design of the machine. Quality (finish) seems to be better than say a Sieg or Rong Fu for a similar size machine, but these all have issues. One of the common problems (seen with many Chinese small mills/lathes) I experienced with my BF30 is that they use metric lead screws with English dials for all the axises (I even asked about this in advance and was assured they were English, the company lied to the distributor and the end user). So out of the box, without a DRO, you have a heavy duty drill unless you do a CNC conversion or plan to replace all the lead screws. The manufactures "fix" is to send metric dials after 6 months of "discussion". Not sure if this has been fixed/changed on subsequent BF30's. I added an Acu-Rite DRO. The quill DRO was faulty, bad switches which were soldered to the board incorrectly. The DRO was eventually replaced, after much discussion. The internals/castings were fairly grit free and most parts were decently machined, but fairly soft steels/castings are used. There are a number of idiosyncrasies (poor engineering) specific to this model, and probably other machines of this type. Small things like fine crossfeed on the quill has a fair amount of sloop before it engages, the spindle clamp did not release well (I added a stiff spring so it releases). The handles for the downfeed hit the Z axis handle in the back, I milled a new slot which repositioned the handles and fixed the problem. Most issues are fixable to a degree, but poor engineering and there seems to be no interest in process improvement in most of these small mills. Most of the paint on my BF30 in the bed and T-slots was painted on oiled surfaces, so it needed to be striped, cleaned and repainted with epoxy paint. The rear Z axis chip guard is very nice (like the SX4), but Y axis is poor, a new one was fabricated to cover the front/rear of the Y axis. Oilers could be better positioned, and some thought given to adding a surface to mount a DRO (for the Y axis). Many of the parts are hand fitted, so things like keys and holes are hand filed or drilled to fit. The BF30 is fairly loud out of the box, although not listed in the instructions, I recommend breaking in the gears and bearings similar to what is recommended in the Sieg mill manuals. In each speed range I ran the mill for 10 minutes at ~25%, 50%, 75% and 100% of maximum speed in the forward direction and then repeated the same in the reverse direction. It still had a lot of clatter until I oiled/greased the end support/spindle/thrust bearing which holds the draw bar, move the spindle up and down while doing this. I used oil to flush out the gunk, and then greased it. Once the machine is broken in, I would recommend changing the gear oil. The original gear oil foamed quite a bit. Replacement parts may be a problem getting, as it took me several months to get parts. This may improve with time.
So the good things about the machine. First, I was looking for a mill with decent quality for small projects in different metals and other materials, I considered the WMD30LV, PM-30MV and SIeg SX4 (also sold by Grizzly as the G0720R). Actually ordered the PM-30LV first, but it never came in. The BF20, SX3 etc, were a bit too small for what I was looking for. The Rong Fu 16-20" models are a bit dated in design/function. I wanted something that could be moved without a forklift, i.e. under 700lbs (use an engine hoist), had variable speed, good cutting capacities, decent ergonomics/functions and was under 3K. Since I do a fair amount of machining in aluminum, the Sieg SX4 was a bit limited, as its maximum RPM is 1600, although it is a very robust machine. There is a nice review, and comparison to the smaller models here: http://www.mini-lathe.com/Mini_mill/rev ... x4-rvw.htm
The BF30 is listed to turn 3300 RPM, in reality it does 2960. Still with 3 gear ranges and a 1500W DC motor, you can pretty much chew through anything you get on the table. I have no problems using 1" end mills or 3" face mills, and the BF30 is quite rigid. There is very little chatter, and cuts are clean and smooth. The tram out of the box was very good, the column is out about 0.002" over 6". The electronics look clean and well made. The fit and finish l would rate to be a bit better then the Sieg SX3/4 based on visuals. The metal base that came with the machine works well and was very sturdy (but poorly painted on the bottom). So at the price point/features, I think the TopTech (Optimum) BF30 is a very good mill, just didn't meet my expectations for a machine that is suppose to have German supervision for design/production. Nevertheless, I think you would need to spend quite a bit more to get a mill that that would bring you up to the next level in quality and capacity.