[DrDucati]

Hello,

I am writing to share my experiences with ordering, setting up and getting started with a Tormach PCNC 1100. It might be helpful to others who are thinking about getting one. Forgive the long story. You may want to skip to the conclusion at the end.

My background: degreed mechanical engineer (CAD and FEA with 15 yrs experience). Close to zero machining experience. Good with tools.

Goal: To be able to machine complex 3D shapes in soft materials, like wood and polyurethane modeling boards, machinable wax, maybe aluminum. Before buying I spent a couple of weeks using the SprutCAM demo software proving that I could mill a complex surface STL file that is typical of what I want to do.

Milling machine: chose PCNC 1100 over 770 for the larger work envelope. Gave up higher speeds. Chose the standard package, except no Kress, 4 jaw chuck, touch tool and edge finder.

Odering: Tormach customer support was excellent: they answered my questions promptly and helped me select the components- even telling me I didn't need some of the stuff I thought I needed. The UPS and freight shipments arrived 7-10 days after they recieved my check.

Other stuff: I bought a selection of carbide end mills from Mari and American Carbide. I got a sample kit of polyurethane foam materials from Freeman Supply.

Setting up: Ran a new 220V circuit in the garage. Rented an engine lift. Followed Tormach directions and watched u-tube videos of assembly. With only a little help from my 120lb girlfriend, I had the PCNC on the stand and fully assembled in one day. Spent another day or so installing the 4th axis, organizing the tooling, becoming familiar with all the parts.

Getting started: The following weekend I set up the computer, became familiar with the Mach3 controller, jogged all 4 axes and did the "First Part" exercise. Cool! Everything was working perfectly.

The first snag: I wanted to try a 3 axis program with a STL file. With some learning, trial and error, the SprutCAM program looked good. But when the cutting began, oops, not what I expected, not the right shape. My first phone call to Tormach Tech Support. Eric was very helpful and easy to work with. I sent him the SprutCAM file and the G-code. He quickly diagnosed the problem: I was using an old version of the PCNC 1100 post-processor that has a bug for 3 axis programs. He sent the new one and it worked perfectly. Thank you Eric and Tormach! Back in business.

The second snag: I wanted to try a small demonstration of a 4 axis program with a STL file. With some learning, trial and error the SprutCAM program looked good: 4 indexed roughing operations and a rotary machining finishing operation. The A-axis indexing operations worked fine. But 5 min into the finishing operation, the continuous A-axis motion got stuck. Stop the machine! Looked in the manual for the 4th axis. Checked rotary table motor coupling. Found that a small allen wrench set screw had worked loose and prevented the motor from turning. Followed directions, disassembled the motor coupling, tightened both set screws, reassembled. Back in business.

The third snag: New workpiece, same 4 axis G-code for STL file. Indexed roughing operations went fine. A-axis finishing operation did not cut the right shape. Contacted Tormach Tech Support. Eric was very responsive again. He suggested that I change the SprutCAM setting from Circular trajectory to Linear. This is where I am now. I will experiment with his suggestion and indexed finishing operations over the next few days.

My conclusions: Tormach is a great company to work with. Customer support is excellent. They will help all along the way, from ordering through hardware and software issues. The PCNC 1100 is very well designed and a good value. SprutCAM is powerful and great for my needs. As should be expected with such a complex undertaking there have been some challenges. But no show stoppers. The PCNC 1100 has given me the capability to do some amazing things! Thank you Tormach!

Wayne

[Magnum164]

Post some pics of the STL files. I gave up on SprutCAM and STL files. That was my only disappointment is I bought SC for it's STL import but it crashed miserably every time I tried one. I gave up on the project but if you have STL's working I may give it another shot...

[DrDucati]

Hello Magnum164,

I have tried several STL files. The first one caused SprutCAM to crash occasionally due to high memory usage (over 2GB). Since SprutCAM is a 32 bit application, even in 64 bit Windows 7 it cannot allocate more than about 2GB of RAM.

Since then I've been more careful about the number of polygons in the STL file. I start with an OBJ file from my modeling software because I am doing organic shapes. The OBJ file is converted to a STL file using MeshLab (good free open source software). My most recent OBJ file has about 90,000 polygons. That leads to a SprutCAM memory usage of about 250MB, which is fine. I expect to slowly increase the number of polygons in my models as I refine the milling process and figure out how much detail is necessary.

If high polygon count is not what's causing your problem, give me some more details and I'll try to help.

Wayne

Post some pics of the STL files. I gave up on SprutCAM and STL files. That was my only disappointment is I bought SC for it's STL import but it crashed miserably every time I tried one. I gave up on the project but if you have STL's working I may give it another shot...

[Magnum164]

Hello Magnum164,

I have tried several STL files. The first one caused SprutCAM to crash occasionally due to high memory usage (over 2GB). Since SprutCAM is a 32 bit application, even in 64 bit Windows 7 it cannot allocate more than about 2GB of RAM.

Since then I've been more careful about the number of polygons in the STL file. I start with an OBJ file from my modeling software because I am doing organic shapes. The OBJ file is converted to a STL file using MeshLab (good free open source software). My most recent OBJ file has about 90,000 polygons. That leads to a SprutCAM memory usage of about 250MB, which is fine. I expect to slowly increase the number of polygons in my models as I refine the milling process and figure out how much detail is necessary.

If high polygon count is not what's causing your problem, give me some more details and I'll try to help.

Wayne

A program should not crash due to high memory usage, with system paging it should give you a notice long before it crashes stating you are running low on memory that you need to free up more memory. Been down that road already. A crash is generally due to an error in the program.

I did have fairy large files and using small end mills which would produce a LOT of cutting paths. SC's memory management was just not what I thought it should be.

For now I no longer use STL files, instead converting to true organic models and creating IGES files for the CAM. More time, but less trouble in the end.

[DrDucati]

Yes, SputCAM shouldn't crash so abruptly with large STL files. But I've found that it works OK with my models so far.

I'm trying to find the best strategy for tool paths: rotary, waterline, plane, etc. Do you have any advice on this? Or a reference?

Could you tell me how you "convert to true organic models"? And how do you get IGES files? What is your starting CAD file format?

I thought that OBJ was the standard format for interchange of organic surface geometry. And STL was the standard format for fabrication- stereolithography, 3D printing, etc.

[Magnum164]

Yes, SputCAM shouldn't crash so abruptly with large STL files. But I've found that it works OK with my models so far.

I'm trying to find the best strategy for tool paths: rotary, waterline, plane, etc. Do you have any advice on this? Or a reference?

No, I never got that far But I was planning to use the waterline as that is what I liked about SC and figured it would be best.

Could you tell me how you "convert to true organic models"? And how do you get IGES files? What is your starting CAD file format?

Actually I said that wrong, its converting from true organic. Starting format does not matter too much. I can import STL files into Rhino3D then edit and correct the mesh several ways, even reduce poly count if needed. Sometimes it's complicated and is basically retracing the STL (or OBJ) and placing meshes over the existing model (retopology). I can then import the Rhino file into Alibre or export as an IGES for CAM. I used to use 3d-coat a lot for retopolgy when I was doing game design.

I thought that OBJ was the standard format for interchange of organic surface geometry. And STL was the standard format for fabrication- stereolithography, 3D printing, etc.

OBJ files were originally Wavefront files, not really standard however since it was easily edited with a text editor, a lot of programs would read/write the format. The actually standard being developed and becoming more/more accepted is Collada. You are correct, STL was developed with 3D printing. only problem is a STL file is generally not great for subtractive type machines, works create for additive though. At least that is true for me. I prefer to convert to IGES.

[DrDucati]

Hello again,

Here is an update to the review. I was working on using the 4th axis for complex surface STL files.

I found that it was necessary to accurately align (+/_ 0.002") the A-axis of rotation with the X-axis of my STL model coordinate system. I used the following procedure: 1) reference the XYZ axes, 2) place a cylindrical bar in the 4 jaw chuck of the 4th axis, 3) use a dial indicator and rotate the bar to center it in the chuck, 4) use a touch tool to set the Z zero position, 5) use an edge finder to set the Y zero position, 6) reference the A axis, 7) center the workpiece in the chuck using an edge finder, 8) level the workpiece in the chuck using a touch tool, 9) set the A zero position, 10) the X zero position is set based on the work-piece.

In SprutCAM I align the coordinate system of the workpiece (an STL file) to the coordinate system of the part (STL file). The Y and Z axes are centered, the X axis is at the left.

When all of this is done correctly the indexed finishing operations align nicely.

I have concluded that I get the best surface finish (in a reasonable amount of time) with 2/4 indexed plane roughing operations (180/90 deg apart) and 4 indexed plane finish operations (90 deg apart). I use extra-long ball end mills 1/8" - 1/2" to cut high density polyurethane foams, 30-48 lb/ft3.

If anyone else has experience with 4th axis milling of complex surface parts I'd like to hear about it. In particular, any advice about finishing strategies, indexed vs rotary, plane vs waterline, etc. would be appreciated.

Wayne

Hello,

I am writing to share my experiences with ordering, setting up and getting started with a Tormach PCNC 1100. It might be helpful to others who are thinking about getting one.