Questions on using a moving gantry style mini-mill...

[Davek0974]

Thanks, lead ins and outs pretty much like the plasma then.

Radius makes sense, already use the different rad rule on the Bridgeport as that can get a bit vocal when it wants to;)

Will apply to this as well, I was going 5mm rough and 2mm finish which fits ok i think, don't really want to go below 2mm unless really needed, but there are some features that are 2mm on the job so can't use bigger.

Been researching fluids and seems pretty much anything goes, even Methylated spirits, but paraffin and oil mix seems popular - pretty much WD40 without the waxy residue ;)

New power supply arrived today, will test it out tonight ;)

[JAZZCNC]

Will apply to this as well, I was going 5mm rough and 2mm finish which fits ok i think, don't really want to go below 2mm unless really needed, but there are some features that are 2mm on the job so can't use bigger.

Unless Rad is critical then it's worth changing rad in Cad just 0.1mm makes difference to small tools and in most cases doesn't make jot difference to part. When designing I nearly always make my none critical rad's 0.1mm over size for this reason because most tools I'm using are round numbers.

[Davek0974]

Good point, thanks

[Davek0974]

On the left side of my part in the OP, there are three slotted holes on the diagonal face.

After roughing the outside with a 5mm tool, these will obviously not be cut, but with my plan to finish-pass the outside with the 2mm tool in one pass, this will mean the 2mm tool taking the full depth cut on these features.

Calculator shows speed for finish pass as 996mm/min as it's only taking 0.1mm off but here it shows speed as 380mm/min as full depth slotting cut.

Options -
run all outside at the slower rate,
run outside as multiple pass contouring at the higher rate,
try and get jiggy with path rules / action points in sheet-cam to slow down in that area,
something else??

[Ger21]

Rough cut the 3 slots in multiple passes before making your full depth perimeter cut.

[Davek0974]

But how to just rough the 3 slots?

They are 2mm wide with a 3mm loop at the base, I was going to go in with the 2mm finish tool.

Is it as simple as defining a second pre-finish pass with the 2mm tool but still leaving the same allowance after?
But then that would not fit into the slot as its 2mm tool in a 2mm slot + 2 x 0.1mm allowance.

Or are we saying go down to smaller tool?

[routercnc]

Hi Dave,

If Sheetcam can do isolated lines as paths then ignore the next bit -
I done something like this before and due to the limit Cut2D features I had to copy the dxf outline of the complete shape into a new CAM file, then used line creation and node editting tools to create a local closed off feature just in that area. Then deleted all the rest of the profile. So you end up with an enclosed local shape using the existing slot/loop features, plus some lines around the outside to make it enclosed. These extra lines are drawn in the scrap area outside the part. You can then select this little profile and do an inside roughing or finish pass to save running round the outside of the whole shape each time.


As the slot is 2mm wide, and using <2mm cutter could be risky, it sounds like you will have to go straight to the finish pass. You could cnc spot drill the centre of the 3mm holes in the loop, then pistol drill dia 1.5mm freehand (as material is thin you should stay inside the hole boundary!) to relieve some of the cutting.