Another newbie question...

[ryan_slaback]

I have been doing some reading recently to hopefully learn from others regarding my new shopbot. There is a lot of discussion regarding holding down of material. What I would like to know if at all possible is it there a point where the pieces are big enough that just holding down the sheet is enough? As one of my first projects I am to make a new set of mailboxes for the lounge at my school. This will require me to cut 80 some pieces 5.75 x 11 from 3/4 melamine. Securing the sheet down won't be a problem, but I am concerned about making sure that when I profile all those pieces they don't go flying. If I use the tab idea is that done as a double toolpath with one on top of the other?

[mikejohn]

Tabbing melamine and removing the tabs with a laminate cutter or hand router with a bearing bit, will work fine.
I don't quite understand what you mean by the double toolpath.

...............Mike

[garyb]

No Ryan it is not a double toolpath, when you add tabs (depending on the size and type)they are added to the tool path you created. Your cutter will either lift up or ramp up over the tab area then continue on with your cut leaving the holding tab.

[jeffreymcgrew]

if you can get away with it, a downward spiral cutter goes a long way in keeping things from moving around on you I've found.

[ryan_slaback]

Mike, By double toolpath I meant having a cut go 3/4 of the way through or so then have a seperate toolpath that could cut a c shape around each (which wouldn't meet in the middle) and thus leave a small section about 1/4 the thickness that isn't cut through all the way.

Gary, I know pretty much squat about m and g code, how do I get the cutter to ramp up and down while it is in the middle of a cut?

[mikejohn]

Ryan
As Gary says, tabs are created with a single toolpath 'lifting' for a short distance.
I work in Autocad and draw in the tab manually.

...........Mike

[ryan_slaback]

Mike, I assume you are using Mill Wizard. I am using Part wizard. I can draw anything in CAD fine but it was my understanding that Part Wizard doesn't go up and down like that.

[tony_mac]

Hi Ryan,

I've put together a short video that explains the difference between 2D and 3D Tabs / Bridges and this can be downloaded from the link below.

Video link (http://www.vectric.com/vcarve-download/shopbot/Tabs.html)

I hope this helps,

Tony

[garyb]

Tony, excellent trainig video.
Ryan if your using Parts Wizard then yur using sbp-code not g-code and m-code. Parts Wizard is a 2d program but has the tabbing feature in it, believe it was added in version 2.
Someone will correct me if wrong, afraid I've only viewed its use, I use ACpro but the tabbing feature is similar.

[kerrazy]

Also, There is a tabbing feature in the ShopBot Control software. Have aroot around there and you will see it, with a fill in sheet so you can adjust length height and spacing.
Dale

[wooden_innovations]

Mike John,

How do you get your files from AutoCAD to the Shopbot? Do you use the .dxf converter in the Shopbot software?

Rodney

[richards]

Rodney,
PartWizard, which is included with the Shopbot, can read the DXF files created with AutoCAD. I use it all the time to create tool paths for my designs.

[mikejohn]

Rodney
There are a number of programs for importing .dxf and converting to .sbp, including (as Mike says) Parts Wizard, Art Cam,Vector and more.
It is important to save in a .dxf version that the conversion program likes. V14 seems to work best for me.

.........Mike

[wooden_innovations]

I currently use Part Wizard for the translation.

The part that I was interested in was the drawing of tabs in AutoCAD and getting the ShopBot to understand that information.

Shopbot's tabs sometimes end up in strange locations and I would like to control where they are located, like in V Carve Pro.

Rodney

[richards]

I've had to manually place those kinds of tabs. The easiest way that I've found in AutoCAD LT, is to offset the part the distance equal to the radius of the cutting tool. Then I draw a grid (on another layer) that is equal to the spacing that I want. Next I use the snip tool to remove all unwanted line seqments. Finally, after saving the tab line segments, in PartWizard, I select the line segments and use the Machine Along Vectors tool to generate the tool path.

I know that my method is not as simple as giving the tab command, but it allows me to nest my parts closer together without worrying about having one tool path cut away the tabs of another tool path.