Re: Is there a comparison between milling machines and software?

Message: 23
Date: Wed, 29 Aug 2001 02:47:56 -0000
From: mprogee@...
Subject: Is there a comparison between milling machines and software?

Hello:

Has anyone had experience comparing actual speeds milling 3D objects
with the range of milling machines under $5000? I am trying to
determine how long it would take to mill a 3D object like the
examples on the Roland website
http://www.rolanddga.com/products/3d/combo/mdx15/mdx15_features.asp
(3D Max head, Lightwave cow)

[I'm not sure how these parts were made on the Roland machine. The cow,
particularly, would be difficult to cut in one piece. It may have been
machined as two double-sided parts that were then glued together. The head
would be easier, but it seems to have undercuts, which would require
registered repositioning.]

using other CNC mills such as:

Sherline
www.sherline.com


AcuMotion Mills
http://www.acumotion.com/products.htm

MicroStep Mills


[The Sherline is a manual mill. There are various CNC retrofit options for
it, Flashcut being the most common. The Accumotion CNC mill is a modified
Sherline, but they don't give much information about the motors they use, or
their performance. Microstep is a controller by Sierra Robotics
http://www.sierrarobotics.com/index.htm that is also used on the Sherline
frame. They claim to get 60"/minute rapids using the sherline 20 tpi
leadscrews, but that's not the same as actually cutting a contoured model
that fast.]


MacNc

[The MaxNC (www.maxnc.com) closed loop mills are fairly zippy. I've run
mine at 90 ipm, although they only claim 60 in their specs. I'm not sure if
this a nominal or actual figure reflecting cutting speed for a 3d object,
however, since contouring operations seem to slow things down considerably.
Their open-loop mills are a lot slower, in the 6-12 ipm range.]


Model Master
http://www.modelmaster.com/

[I've never seen the Modelmaster mill in operation, although they do have a
video on their site. It doesn't seem to be feeding very fast, but it has a
high-speed spindle. Since the maximum tool size is 1/8", it will not cut a
roughing pass as quickly as a mill capable of using a larger tool.]

I have consulted the webmaster for Desktop CNC www.desktopcnc.com
also. Such a comparison does not exist yet.

[It would be interesting to see, although the experiment would have to be
structured to compare "apples with apples". A standard part, using the same
NC program, and cut with the same tool in the same material would be
necessary to make a valid comparison.]

I am trying to figure out how quick you could mill a rough pass and a
good pass for a 3D model (STL STIS, or DXF format) such as the model
Creature Lab dinosaur at
http://fxrealm.temp.dataphone.se/index.shtml.htm The model could be 6
inches in height, 4 inches in width, milled in foam, modellers wax,
or wood.

[This looks like it would be a difficult project to carve on a 3 or even 4
axis mill. The areas in between the limbs, particularly, would be
problematic. Like the cow, it would need to be cut in sections, and the
sections would have to be assembled, much like a plastic model kit. The time
it would take would depend on the degree of surface detail required- skin
texture, for example, would take much longer to cut, using tiny bits, than
the basic form. ]


Also, has anyone done a comparison of milling software?

[By milling software, do you mean the software that actually runs the mill,
or the g-code interpreter software that translates the model files? ]

Andrew Werby
www.computersculpture.com