It's mostly because as they have the Y axis stepper motor towards the rear of the table under the column rather than hug out the front like most DIY conversions so that limits travel a bit.

This is why the Y axis movement is less than a similar sized SX3

Turning the limit switches off gives a little more movement on the KX3 which I have done when machining flywheels.

Edited By JasonB on 25/02/2022 19:52:14

They came from the Sieg Design

Fundamentally these are manual machines with CNC bolted on afterwards.

With the exception of Deckel and Bridgeport style mills it seems to have "always" been normal practice for manual mills to have restricted Y axis travel towards the column so the outer side of the table cannot be covered by the spindle centre line. I've no idea whether there are fundamental engineering reasons. Its just the way things have "always" been done.

Similar to the unreachable ends of the table at the left and right ends.

I guess it provides safe space for work-holding devices like the common step bolt and strap sets.

Whether this was intentional right from the start of vertical mill evolution or whether some mills happened to be made that way and the spare space was found useful so it became the norm I know not.

It seems clear that vertical mill design evolved from the simple drill press, which inherently has unreachable table space, rather than the planer which is able to machine over its whole table. Presumably a matter of price / performance ratio back in the early days as a simple "drill press with x-y table" layout would have been less costly to make.

Modern full on industrial Vertical Machining Centres are made so the spindle can cover pretty much the whole table. To eyes used to manual vertical mills the tables look very small. Especially in relation to the big box enclosure.

Although possibly more objectively accurate, specifying machines by the actual area covered by the spindle rather than by table size would not be a successful sales tactic!

Clive

Jason

Apologies for not keeping up with things. Hadn't realised that the SX2.7 had enough travel to reach the edge of the table. The little Taig CNC on my other bench that I've never got round to using pretty much can too.

I appreciate that the castings and other details are modified to be more CNC orientated rather than simply doing a factory version of a DIY bolt on bits conversion to a manual machine but the overall concept is still very similar. Presumably for manufacturing cost / performance / capability ratio reasons. Generally when you look into the "Why did they do it That way when This way is (theoretically at least) so much better?" the answer tends to be "Wanna pay two (or three or X ) times as much!".

Industrial, enclosed, CNC VMC machines are generally inverted compared to manual machines with smaller tables running on longer ways so you don't have the limited dovetail engagement at extreme travels issue. Expensive to make but great for rigidity. In exchange you have work-holding issues, if you want to exploit the full machining area there is nowhere for hold-downs to go.

Its arguable that a table narrow enough for the spindle to cover the whole Y axis travel is too narrow. A bit of extra width on the outside for hold-downs, clamps, positioning fence for repeat jobs et al is very useful at times. I drive a Bridgeport these days and clamping, work holding et al can be a right pain when the area to be machined approaches the table width.

After a bench top mill I thought a 9" x 42" table would be more than enough! Third job said "Nope!". But I'm home shop guy working in 12" to the ft scale, not model maker. My biggest job, so far, was 14 ft long.

Clive