[Grant Nicholson]

I'm not clear on what "Peck Lift" means. As well, does feedrate make any difference in a strategy based on plunging? The manual doesn't really address the drill centers strategy as well as I'd like - any advice on optimizing these toolpaths would be greatly appreciated, as I feel the drilling of my jobs is taking too long and heating up my endmills unecessarily...
Grant

[tgm]

Grant,

Peck Lift is the drilling option whereby the drill will drill to a certain depth and then retract to clear chips before finishing the drilling. The 'lift' portion is the retract distance between plunges. You can set the number of passes, in this case 'plunges', in the Strategy Definition dialog bos under PASSES. Peck lift is also set here. In this dialog you can also set the PLUNGE rate of the drill.

As far as optimizing, you need to go to Simulate 2D and set the ordering of your drill strategy. Go to 'OBJECT ORDER and open up the COLUMNS menu and you will now have a choice on ordering the drill sequence. Play around with these options and you should find what you want.

As far as drilling holes with and endmill, this is a perfect way to start a fire if you are using a vacuum table. The bit heats up upon exit, the vacuum is like a bellows on steroids and whala.....one litte spark now starts a fire below your material and into the spoilboard. More than one shop has experienced major fires with just this scenario.

Hope this hepls, if not repost and we will see what we can do........

Good Luck,

Tom in PA

[Grant Nicholson]

Hi Tom,
I'm assuming you're suggesting that simple drill bits are less prone to generating heat than endmills...
Thanx for the info. If I do 3 passes, the bit lifts with each pass back to the surface. If I use peck lift, the bit doesn't come out all the way, by the sounds of it.
G

[tgm]

Grant,

You are correct. With 'Peck Lift' the tool only retracts by the 'peck' amount, just enough to clear and break the chip. Much more effficient than 3 passes.
As far as heat goes, the correct bit will spit the chip out and give you a clean hole everytime. Beware of the 'cheapo' carbide tip boring bits, they just don't last and part quality will suffer.
We switched years ago to solid carbide 5mm boring bits and havn't looked back. The cost is higher but the quality of both the tool and the hole is far superior to anything else we have ever used. Plunge 3/4" deep in twp sided melamine and have a perfect hole with no burning and a clean entry and exit with no chipping. With 5 and 8mm bits you do get what you pay for.

Good Luck,

Tom in PA

[Grant Nicholson]

Thanx Tom - I'll look into boring bits for straight up drilling, such as shelf holes in melamine.

I'm assuming also that if creating a hole that's larger than the bit you would use an endmill (for example, if I need a .16" hole I could use a .125" endmill with a routing offset path). This is how I've been handling some of the drilling projects currently, such as alarm system panels full of various sized holes.

[tgm]

Grant,

The best boring bits we have found, using trial and long run experience, are the solid carbide bits from CMT in Italy. The cutting geometry on the end cuts really clean holes in melamine and with a good spoilboard and the right feed/speed the exit is also clean. They cost 3x what a normal tipped bit cost but lasts at 10x longer and can be reground.
As for the 'larger than std' holes, yes we just bore them out with a suitable size end mill. You can set the 'lead in' large and the end mill will actually spiral down into the hole in one pass. You can see this when you run the simulator. It saves time when using a small mill to plunge deep where you would normally use multiple passes.

Good Luck,

Tom in PA