Fixed head/bed milling machine question

[krems]

I can see now that I will eventually need/want a heavier more solid milling machine in the future. I would probably go with a 40 taper machine of some type. I really have no need to be turning the head to various angles. I keep looking at the bed type milling machines or ones with a fixed non rotating head. Are these machines inheritantly more rigid and accurate as compared to a standard bridgeport type. What were these machines originally designed for??

I would like to have the cnc option as well (prototrak / mill pwr) I seems that this type of machine would make a better manual/cnc combo machine especially for the one machine guy. Price wise these machines w/ cnc are about as expensive as lower level cnc machines.

Any thoughts about fixed head manul machines

Krems

[John Stevenson]

As I posted in another thread I can't see why any of the machine manufacturers 'converted' the nod and tilt head machines to CNC although I think this only applied to Bridgeports [ shudder ]

You introduce two points of weakness at the double knuckle and then have to drive a less than perfect quill by an overhung ballscrew and nut which just wants to tip.

The fixed head BOSS machines as in Jason's "Is this a tram problem " thread had larger than standard quills and the ball but actually runs concentric round the outside of the quill, a very good design.

I can only put it down to either a cost cutting exercise or then had a rake of bits left over on a Friday?

.

[SVS]

Fewer joints means more rigidity and no need to tram the head. 90% of my work is flat, square, and parallel type stuff so I get along nicely with a Cinci Vertical bed mill, and Cinci Horizontal knee mill. Angle the work when necessary-Not the mill.



Unloading the Cinci Vertical.

Scott

[krems]

svs

Now thats a milling machine.....

Has any one looked at the Southwestern industries CNC/manual machines (not the bridgeport style but the fixed head type) I've heard both good and negative comments. They seem like a good machine for what I'm looking for.
They have a nice brochure out that I just got. Expensive though. I wish the quill diameter was a little larger in diameter (3.93") especially for a 40 taper.

John S.........I'm not a fan of the etended quill either.


Krems

[Spin Doctor]

I've run both the 2 and 3 axis CNC versions of Southwestern Ind. Trak control. In reality the control is the same as the control used on the BP conversions. Generally I like the Trak control as it is a pretty simple to use CNC. It has a couple of quirks but then just about every system does. It allowed the importing of CAM files for more complex stuff but for most CNC operations it really easy to learn. Now the Trak bed mills the heads do rotate on an axis parallel to the machines Y axis. So tramming has to be done occasionally. IMO the tables are longer than you need for most jobs so they do have a problem with table sag but not as bad as a BP. Cast Iron isn't that expensive so I have a hard time seeing why they did not make the bed wider than it is. Although looking at their website I see they now have the bed mills in 2 sizes http://www.southwesternindustries.co...bedmills.shtml.
In reality for the most part I have found that 2 axis CNC mills are generally more usefull than 3 axis unless one is involved in contouring type 3D work or you have a number of repetitive pocketing operations.But then I really don't have the experience in mold or die work to go by. These machines however are no replacement for a true CNC machining center*

*Trak for a few years was offering a model that was billed as a second operation mill. Similiar to the Hass Mini-Mills http://www.haascnc.com/details_VMC_NEW.asp?ID=39 with a table around 14" square and 3 axis. We tried to get them to buy one at work as it took a really small footprint as far as floor space was concerned and a lot of our stuff wasn't that big that it required a larger table.

[krems]

SD,

I agree that the tables are too long especially for what most people need.. I would give up 6-8 inches (X axis) in length to get another 2-4" in y travel.

I looked at the Haas site for the first time today. They have an extensive line. Those Mini / Super mini CNC machines look interesting. I may have to keep my manual machine and get a dedicated CNC machine. I was hoping to. get by w/ one machine as space is limited. I do like the idea of having both manual and cnc capabilities on one machine - probably because I'm new to cnc and am woried about the learning curve.

Krems