3D Help

[phardy79]

Ladies and Gentlemen,

I have ventured to the Dark and side of shopbotting,(3D). I bought Cut3D and it is a very useful tool for creating 3D cutouts. I am unsure about the tooling necessary to cut out this object.

The part is approximately 4” thick x 10” wide x 16” long. I know that I am going to use a 1/2" end mill for the roughing pass, but what tool should I use to cut the finishing pass? I am thinking about a 1/4 “ ball end mill to save a little time. Also, how do I prevent the little snipe of the bit on the vertical sides? I am unsure if there is any draft on the sides. If anyone can help, I would be very appreciative. Thank you!

9068

[hespj]

Paul,

When finishing I use as large a diameter ball end cutter as I can to reduce step-over marks. Or to put it another way, I use as large a cutter as possible to reduce the number of passes (for a given roughness).

Here it looks like the size of the cutter will depend on:

i)....how big a fillet you are willing to accept between surfaces. (Although if the software will do it you can recut smaller fillets later with a smaller dia cutter [the fillet areas only, not the whole thing]).

ii)...what cutters are available that can reach down that deep vertical face. A 1/4" cutter 4" long might not be available, and might flex to much anyway. Alternatively, use another cutter on these deep areas.

You say "finishing pass". You'll probably find it'll take at least two finishing passes. One to finish the more horizontal areas, and one to finish the vertical areas. You might find that you need to do as many as:

i).....horizontal finish - X direction
ii)....horizontal finish - Y direction
iii)...vertical finish
iv)...recut fillets
v)....finish deep vertical faces

but you can probably do less.


"how do I prevent the little snipe of the bit on the vertical sides?"

Not sure what you mean by this.

John

[paco]

You didn't tell about the material you intend to use.

Have you considered the 'Slicing' approach?

Assuming you have access to 4 inches thick stock, I'd say toolpath in Cut3D, save your file (*.V3D) then import the Cut3D file into VCP to toolpath 2D profiling cut out toolpath to complete the machining. Say your me and cannot chuck anything larger than 1/2" shank tool bit, the longest 1/2" CED tool bit that I have is 2-1/2" CEL. You will be able to cut it off almost all around but the most thickest part.

I made a little demo file of the second solution but the TSB forum cannot host the file (570KB). eMail me if you want to have a look at it.

On a such project, plan ahead some time to preview the process both in CAM software AND in your mind. I have finished a similar project once with a long 1/2" CED flush trim bit.

[phardy79]

I am going to cut the part from one big block of MDF.

[phardy79]

Well, I cut my 95 lb. block of MDF with several successes and many lessons learned. 1st thing learned, make sure that your bits are long enough to reach the bottom of the part without the dust skirt hitting the top of the part (duh). Next, when using Cut 3D program, make sure you use the 45 and 135 degree finishing tool path. When those intricate bits get put into inside corners when using the x axis finishing path, the bit will always break (opps there goes $25, $50, $75). Good thing the bits were 6" long to start. Now they are about 4". They still can be used. It always amazes me that when a bit snaps, the part that breaks off just drops to the table and does not shoot across the room.

Another lesson learned; make sure your hand does not slip down the spiral blades on a new cutter when tightening the bit into place. If it does, make sure you have plenty of band-aids on hand (literally).


Paco, thanks for your good advice.

I am very glad that I spent the extra $150 for the 14" Z axis. I highly recommend it. If I would have had a little longer bit on the roughing pass, I would not have had a problem with the dust skirt. I will post pictures soon of the process.