Sieg X3 vs BF20 Mill

[CADScott]

Woo Hoo first post!

Hi all, I am a long time lurker on this site, and have finally got the space and money to get a mill for my small home shop.

I am tossing up between the Sieg X3 and the Vario BF20, and would like some opinions on which would be a better choice.

My comparison on the specs of each (In metric, I'm from Australia):

SIEG X3

DRILL CAPACITY : 25
FACE MILL CAPACITY : 50
END MILL CAPACITY : 25
SWIVEL ANGLE : 0
TABLE SIZE : 550 X 160
X TRAVEL : 160
Y TRAVEL : 300
SPINDLE TRAVEL : 80
MOTOR POWER : 600W AC
SPINDLE TO TABLE : 350
SPINDLE SPEEDS : 100 - 2000
SPINDLE TAPER : MT3 / R8
WEIGHT : 165
PRICE : 1700

BF20

DRILL CAPACITY : 20
FACE MILL CAPACITY : 63
END MILL CAPACITY : 16
SWIVEL ANGLE : 90
TABLE SIZE : 700 X 180
X TRAVEL : 175
Y TRAVEL : 480
SPINDLE TRAVEL : 50
MOTOR POWER : 600W DC
SPINDLE TO COLUMN : 230
SPINDLE TO TABLE : 380
SPINDLE SPEEDS : 180 - 3200
SPINDLE TAPER : MT2
WEIGHT : 113
PRICE : 1400


It seems to me the BF20 beats the Sieg X3 in everything but spindle travel and the taper it cames with, but I guess my biggest concern is the difference in the weight of the 2, I can't understand why the X3 is so much heavier, it looks like a lighter machine, does this effect the rigidity of the the BF20?

Any other opinions on this comparison?

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[Alan Wright]

On paper, the BF20 looks better. I rather suspect based on the price that it is not actually up to those specs. There are machines, such as those made by Wabeco, Prazi, and EMCO Maier, that employ superior designs and can get more performance for less weight than the Chinese counterparts. A Wabeco F1210E, for example, is a more capable machine than the X3, at about 3X the price but somewhat less weight. Not sure if the Vario line could be in that league, considering the price.

[CADScott]

Actually, looking at the Wabeco F1210E, I think the BF20 is a cheap Chinese copy of it, it looks almost exactly the same, and has pretty much the same specs. That is a very nice looking machine, but the price is a little bit high for my tastes!

[mchabot]

Hi,

I do not own a X3 or BF20, but they are quite common here in France.
Some BF20 users report broken gears (they were mounted with plastic helical gear), ala X2.
No problem reported with the X3 since gears are metal.
So this with the CM2/CM3 difference make the choice towards the X3 (for me at least).
Note that a luxemburg dealer sells SX3 with SA30 spindle instead of MT3

[neilw20]

Heavy side loads during milling make it difficult to hold morse taper.
MT3 fine for drillng, but not for milling once you load them up.
That's why I chose my Super X3
3600 RPM and rotatable head is great.
A mill can't be too heavy. The more rigid ther better.
The R8 spindle is stiffer than a MT3 also.

[machinechick]

I live in the USA and have a BF20L which is labeled as a Top Tech BF200. It has an Optimum tach, motor, owners manual etc. It is fitted with a MT2 taper with a self ejecting M10 drawbar. Has a large table with lots of work envelope. I use an MT2 ER32 collet with it, as I had a set of collets from a previous machine. I'm very aggressive with it and have had no rigidity issues. All the gears are metal including the helical. I know alot of users would be put off by the MT2 taper, but it has posed no problems (you need to bolt it to an equally rigid base/table). In my opinion, on machines of this size the only reason for an R8 is easy access to tooling, however, if it mattered to me I could have got the Bf20 clone from Lathemaster, which has a R8 spindle. This machine design is rock solid and a real performer for it's size. To say that I am impressed is an understatement. The only issue I had is having to develope the awareness that my z-axis gibs better be unlocked when I lower the head or the practice will introduce some backlash which became apparent upon releasing the gib. I'm very enthusiastic these machines are becoming available in the US as I got real sick of the bench top machines who's primary design consideration seems to have been how many crates the exporter could fit in a cargo container!

[CADScott]

Thanks for the info! I am a few days away from picking up the exact model you have, which is branded as a Mach-tech here in Australia, but has the same Optimum tach. I guess they are all made in the same factory.
I have been flip flopping between different models for nearly 18 months looking at my original post date, but have now decided on the BF20. My decision was helped a lot by the price difference, in Australia I can get the BF20 for a third cheaper than the basic X3 mill, and it seems to be a much better machine.
I will be picking mine up after the start of July (Next financial year), and will be converting it to CNC straight away, which I will post progress pics of when I start.

[machinechick]

Posting this as a correction. Just thought I'd check the gears again, and the the helical gear is indeed a type of plastic, suppose this is an intentional "weak link" in the drive train, as it's easy to get at and replace. The controller also has a auto shut off, but the only time I've had it kick in was when taking a heavier cut with a 50mm facemill. Suppose that's why I didn't "discover" the composition of the gear sooner. Gonna have to get a spare or two just in case. Hope, you still get the mill, it is a good one. I just put some glass scales and a dro on it, if I could have got the Optimum "bolt on" CNC I probably would have gone that route instead. It will be interesting to see your conversion.

[Radical!]

I can't understand why the X3 is so much heavier, it looks like a lighter machine, does this effect the rigidity of the the BF20?

Any other opinions on this comparison?

DIY optional rigidity fix for BF20. >>>
Not mine, but great idea if you want to add some bulk to your project.

[machinechick]

I have never had any issues with the rigidity of the BF20. More than weight affects how rigid a machine tool is. The gibs of the BF20 are much more substantial than the X3 and, in my opinion, have a superior design for adjustment. The leadscrew nuts are also much larger. As for the discrepancy between the two machines and the weight, I wouldn't be too surprised if the same person who rated the "mini" lathes motor at 3/4 hp, was the same individual that weighed the mill!
The only thing I want to change on my BF20 is I don't like how when I rapidly raise the head with the manual handwheel my whole table shakes, it could really use a proper counter weight.
I think it would really be cool to mount a stepper motor on the top of the column that would have a controller and readout for manual use, or maybe even a geared dc motor for rapid movement, while leaving the handle for the fine adjustment.

[CADScott]

I agree with the weight issue, from what I have seen, the quoted weight of the BF20 varies from 106kg to 165kg depending which site you look at, and I would tend to think it is closer to 165kg.
I also agree that it appears to be more rigid than the X3, I have demoed both together and was much more impressed by the BF20.
With regards to the head shake, I noticed that as well, and was planning to put a couple of gas struts to offset the head weight. I can get struts custom made pretty cheap (About $20 each), and was going to mount one on each side.

[machinechick]

I have three or four sets of air springs laying about, I'm really tempted to use one to help support the weight of the head (in my mind it doesn't have to support the whole load just 2/3's of it or so). It's intuitive to want to put one on each side of the head so as to not introduce an "imbalance or twist" but I wonder if that is really necessary if the gib is properly adjusted etc.(sepecially since I have a glass scale on one side), I also wonder if it would make any difference if one put the airspring on the side of the head where the gib strip is? On some level I'd like to put a pulley arrangement on the top of the column and make up some cast iron "weights" hanging off a cable, but I'm really running out of space! Another concern I have, especially as I'm keeping this mill manual unless I get some shop space for another mill, is the weight of the head a relevant "counter force" that contributes to the overall rigidity of the mill?

[CADScott]

I agree that you wouldn't want to offset the whole head weight, I figured around 80% - 90% offset so that the head would always drop if released. I would also put a strut on both sides, just to ensure the smoothest movement.
As for the rigidity, I would think that the overall mass of the machine contributes to this, and since the struts do not reduce this, it should not be effected.