Building a new CAD station - I need Murc's help.

[ND66]

It's just a 3-axis, but the parts can be fairly complex.

I know... .


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[gt40]

Dammit, can't get that solidedge 2D to install.
says I've already got a solidedge product, and need to uninstall it first

[ND66]

Dammit, can't get that solidedge 2D to install.
says I've already got a solidedge product, and need to uninstall it first

.

[spadnos]

welcome to the world of hifeed machining. A 3" cutter moving at over 200 ipm removes alot of material very quicly

Ah - that's not so fast If I ever get off my butt and finish the CNC conversion, my BP will run 180 IPM or so. I expect that to be too scary though, so I'll probably limit it to something a bit more sane. (though I'm sure I don't have the spindle horsepower to remove that much metal, so I'd have a depth of like 0.005 with a 3" cutter)

I normally break my programs up into 4 or 5 sections
A roughing pass with a larger cutter that removes as much material as possible
A 2nd and possibly a third roughing pass with a smaller cutter to bring the material to a point where in the next pass a semifinish cutter will be in a quasi constant material load,
and a final finishing cut where the cutter remove a small controlled amount of material.

Sure - standard roughing and finishing cuts. That's what I'll be doing

The first cuts are fairly quick, and I like to actually verify the individual steps on screen before I cut - this prevents ouches.
The longest cut is usually the last, the cutter only moves over a small amount between steps, and is at a controlled feed rate to minimise cutter deflection.

Do you need to run a simulation of all the motion, or just look at a preview of the full toolpath? If you take a look at EMC2 ( http://www.linuxcnc.org ), there's a very nice user interface called Axis that gives you a toolpath preview that you can manipulate (rotate, zoom, pan). Generating the preview is pretty quick - on my Opteron machine, I can load a 70000 line program in ~30 seconds. Once loaded, I can manipulate the preview in very smooth realtime (on a 1920x1200 monitor, using a 7800GT). Recently, there has been some work on making "remaining metal" previews as well - these are models that show what's left after running an NC program. That software isn't too easy to use yet, but it is interesting.

Correct! What can be done thou is changing the affinity of the program to a particular CPU, leaving the other processes the hog the other.
What I can also do is open another instance of the program and dedicate the other CPU to it.
I'm not sure how this will work with dual cores thou???

A single CPU with dual cores won't be as good for you, since they'll share the same memory bus (and cache, for most of the Intel line, I think). It'll still be more responsive than a single-core system, but you will impact the CAM process speed.

Most of the final NC programs are filtered (I will typically filter a finish cut with a .0002" tolerance) so the final sizes are relatively manageable. On a larger part with an 8 hour finish cut the file size will be in the 2-10 mb range (depending on the complexity of the part).
There is quite a bit of proccessing involved before this, and Mastercam can and will ballon memory use over 1gb.

Interesting. What kind of "filtering" does it do? I can only see the need for some type of filtering if you start with a "rendered" model, like STL. CAD models like DXF (unless they're stupid DXF with curves approximated as lines), NURBS or Parasolid should result in relatively small programs.

This would be the budget for CPU/mobo/PSU/HD
I will have to make some compromises at first, but it will definetly give me a good start.
I can probably get another Firegl in a PCI Express version on a favour

Heh - well, as long as you know you're making compromises One other thing to consider is to use a separate computer for toolpath visualization. Computer 1 runs MasterCAM, computer 2 runs the toolpath preview, and #3 runs the mill. That may not help though, since you probably aren't generating a new toolpath while looking at the old one.

- Steve

[gt40]

Ah - that's not so fast If I ever get off my butt and finish the CNC conversion, my BP will run 180 IPM or so.

I'd pay to see that
I will remove about .06" with th 3" cutter, and have had it as high as 350 ipm, but I found that workpieces may tend to 'walk' at that speed
I've got a 37Hp spindle, and it shows a fairly high load at that feed rate.

Do you need to run a simulation of all the motion, or just look at a preview of the full toolpath

I will do a full simulation, showing the tool motions, any tool crashes and the remaining material. Sometimes this helps in deciding what path I'm going to use next. Looking at the actual tool paths is a fairly quick proposition.
Some of these blocks have a few thousand dollars of work before I get them, and can be worth the same in machining time, so buggering one up is not an option.
All of this is done inside Mastercam

What kind of "filtering" does it do

Typically the toolpaths are broken up into tiny little lines (depending on the accuracy required, and the quality of the finish), so filtering will do a few things.
Smaller moves that can be aproximated with one larger linear move(within the tolerance selected) will be combined into a single straight line.
A series of smaller moves that can be combined together to form an arc (within the tolerance). This can be done in the xy, xz, or yz plane.
Most of my work involves complex 3D models. STL models are usually not accurate enough - they tend to show facets on the finished parts.

Typically the parts will require no polishing after I'm done, they would look somthing like the attachment (part is roughly 15wx15dx12h") as a reference the jaws on the vice are 7" wide

[gt40]

Just waiting to see which video card is available to me.
I suppose my other option would be to pick up something like a p5pe-vm and use my existing Firegl (honestly I didn't know anyone still made AGP motherboards )

[MultimediaMan]

I just built up a Dual Opteron SFF w/ a pair of Opteron 265s...

AGP card, yes, but it is a Quadro FX1100 (I almost stole an FX2000 on fleEbay but some one sniped me...)

Fast and powerful...Total investment: $1000USD give or take a few cents... One sale on the barebones, Three Auctions and some Forum Trading...

However, I will second using a Core 2 Duo with a serious chunk of RAM; I have an HP7700 USFF sitting on my desk at work Dual Core 3.6GHz that boots a production build of Windows XP 32bit in just under 8 seconds, and boots in under 6 seconds with a clean install of Windows XP 64Bit.

[gt40]

Alrighty then,
Here's what I've come up with for the moment

Asus P5B-E $175
E6400 cpu $270
1GB DDR2 pc6400 $135 (I will upgrade to 2GB later - this is still more memmory than I have now)
74GB WD Raptor 10,000 rpm $175 (I only need the O/S and CAD software on this system)
Asus AX550GE $60 (temp - I have a free Firegl coming, but I'll have to wait for it)
Case /power supply I have already)

total cost $814 Cndn

This is all from one vendor, I really don't feel like saving a few dollars to have it sourced form 2 or 3.
Any comments/suggestions are appreciated.

[schmosef]

You are getting really good pricing. Where are you buying this from?

[gt40]

Premier computer
here's a link to the CPU:http://www.pccanada.com/viewitem.asp?id=4777
Infonec has a better price on some of the items, but they don't seem to carry the P5B-E, and I'd like to get everything from one source.

[schmosef]

Take heart in that the pricing you are getting is very competitive.

Because of the cash discounting, it's very close to my cost.

[gt40]

thanks for checking for me.
Even with the 2% premium for a CC order it still seemed a good deal.

edit: Just ordered it, and was charged the cash discounted priced thru my cc