I bought V21 a few years ago (my weakness, good salesperson), thinking it may be a good interface between my SolidWorks 2004 and an as yet to be defined CNC machine.

Since then I have graduated to SolidWorks 2007 and have gained access to an Excellon 105DP PCB routing/drilling machine with a Z-Axis depth of 5" and a 15 x 20 accessible table.

I have no NC experience; that said I did write a drilling program by hand with some success so I have a limited idea of the commands needed to make the spindle go here/there, head up/down and that's about it.

I would like to use the Excellon to make fins and centering rings for my high power rocket hobby, as well as do some 3D routing to make small plastic parts and molds for Urethane casting.

Now for the questions:

Given the above, where do I start? I have tried the tutorials given with V21 but it expects you already know what BobCAD is all about.
Where do I get practical information on spindle feeds/speeds?
Bit selection for a given material?
How do you hold pieces being cut?
How do you find your way around the work platen (where is x,y,z = 0,0,0)?
Where can I find concrete examples (using V21) that go from a SolidWorks SLDPRT file to the NC codes to cut say a circular rocket centering ring in G10 or plywood?


Any and all guidance would be appreciated, even if it is an admonishment to "RTFM" as long as it is accompanied by the relevant "FM". Attached is an example of what a centering ring looks like and the rocket that uses them.

Thanks,

David

Given the above, where do I start? I have tried the tutorials given with V21 but it expects you already know what BobCAD is all about.
Where do I get practical information on spindle feeds/speeds?
Bit selection for a given material?
How do you hold pieces being cut?
How do you find your way around the work platen (where is x,y,z = 0,0,0)?
Where can I find concrete examples (using V21) that go from a SolidWorks SLDPRT file to the NC codes to cut say a circular rocket centering ring in G10 or plywood?



1. The Training Professor video series covers nearly all aspects of Bobcad. Available on Ebay or BC.

2. http://www.discount-tools.com/technical.htm for one...or Google cutting speeds feeds for wood

3. For your materials and parts, I would recommend 2 flute 1/4" carb end mill or router bit. There are many factors which influence decisions here. (ex. spindle RPM and machine rigidity)

4. Your parts.... Screw workpc. to sacrificial waste board. Cut center hole. Screw down thru center hole to clamp part. Cut O.D. ... Again lots of different ways to attack this.

5. Most machines have a home location from which you can set a fixture offset zero location and reference that fixt. off. in your program. Some machines you can set your machine zero wherever needed to run program. Read your manual.

6. Unless you're designing in SW, these rings are simple in BC. Could even write a script where you fill out dialogue box and everything else is automatic. Otherwise, import them as .sat (my preference), Extract Edges, Move to Z (if needed).

Sounds like you just need to start somewhere. Don't worry about mistakes, we all make them. Single block, dry run your programs at a safe Z distance until you understand whats going on.

Is there a post available for your control? That can be a headache source for which you can get a lot of help for here.

Oh... and read your manuals.

Good luck,
moldmker

Hi David, Cool hobby!

Those rings will be a great start for you with cnc. Should be some simple pocket work.
It's kindof hard to direct you as some of the stuff you need isnt BobCad but just an intro to how to use your machine or "What is a pocket".

I could tell you 2 things. Looking into the training classes offered up by BobCad could be a great place to start. Make a call and see what their doing. Many others have had great stuff to say about learning how to do stuff from those classes. I think the guy's name is Sorin and he has a site called:

http://www.cadcamtrainer.com

He has some free intoductory videos on his site that are a good look also.

If doing the training classes are beyond you then there are alot of people in these forums that can help, but starting from so much of a begining, it will be a long process and take some extra time as forum communications can be a bit slow.

Good luck!

BTW: Youtube has many videos of stuff happening so maybe parusing them you could see some basic clamping techniques and such. Basically clamping your stuff to the table requires the tooling (Clamps), sometimes creating your own jigs and such.

What you are trying to do will be very simple!

If you can write some simple programs by hand you shouldn't have a problem with BobCAD.

Hold downs Zero all these things are easy to setup on a router.

I am sure you'll get all the help you need right here.

If you want you can call me directly and I help you though anything you want.

727-744-2276

Thanks for the quick replies, yes, I should be more specific with my questions and direct them to the appropriate forums, thanks.

I do have the reference manuals for the Excellon controller, but it is a bit like learning French reading a dictionary. It is possible, just not likely. So in this forum let me try to understand the basics of BobCAD/CAM.

Basic Understanding:
BobCAD is an application that enables the user to import/create/edit objects much like any CAD program.
Once an object is imported/created a feature on that object can be assigned to a tool path
NC code can be generated for a specific tool path
The NC code is available for creation/modification
The NC code represents an ordered sequence of tool paths based on parameters including tool shape, diameter, material being shaped...
The tool paths can be simulated by "running" the NC code.

Am I far off? Please feel free to steer me in the correct direction. :confused:

That sounds ok.


Call Allen! A quick conversation will be worth a thousand typed words.