What is the best way to drill holes?

[jharvey407]

I'm new to CNC work. I have a background in electronics and have recently built a CNC router out of 8020 extrusions with a PorterCable 690 1 3/4 hp router as a spindle. I have a VFD and can run the router between 8250 rpm and 27500 rpm.

I work in the marine industry and will be cutting mostly wood, plastic such as StarBoard, some aluminum as well as engraving electrical panels and other engravable materials.

What is the best way to drill holes in these various materials?

It seems that using the 1/4" endmill is a great way to drill 1/4" holes, but what about smaller and larger holes?

Are there special drill bits with a 1/2" or 1/4" shank available?

Is it reliable to spiral drill holes larger than 1/4"?

Any ideas are welcome. If this topic has been discussed before feel free to post links, I'm new here and still don't know where all of the good info is.

Thanks,
James

[ger21]

First, how are you running a 690 with a VFD?

8250 is still pretty high for drilling. I'm using a Super-PID on a 690 and can drill at 5000 rpm.

If you need holes larger than 1/4", I'd just route them.

For smaller holes, Precise bits has 1/8" collets, and different size bits with 1/8" shanks. Precision solid carbide tools for woodworking and metal forming.

[jharvey407]

First, how are you running a 690 with a VFD?

8250 is still pretty high for drilling. I'm using a Super-PID on a 690 and can drill at 5000 rpm.

If you need holes larger than 1/4", I'd just route them.

For smaller holes, Precise bits has 1/8" collets, and different size bits with 1/8" shanks. Precision solid carbide tools for woodworking and metal forming.

Correction, I am running the 690 with PWM not VFD.

I could probably run it as low as 5000, but I need to check the specs on my PWM board.

I have looked at the drill bits at precise bits and that looks like a good solution, and as you say I can always route holes larger than 1/4".

I'm still in the learning phase of running my machine so I am always looking to learn from the experience of others.

Thanks for the help.

[Dean448]

I would also be interested to hear how you pwm speed control the 690. That unit has an internal module that varies the freq of the line voltage to change speed. Did you replace it somehow?

I use 1/4" and 1/8" bits to do just about anything. Thats within the limits of the depth of the bit. The CAM package I'm using has the option to cut inside or outside the profile, or completely inside the profile. On a circle it simply plunges into the center and sprials out to the diameter. I found that routing holes is much better then drillig because you only need a bit smaller then the hole and changing size slightly is no problem. Also no chipout and drill bit walking.

So the answer to your question is software.
Dean

[jharvey407]

I would also be interested to hear how you pwm speed control the 690. That unit has an internal module that varies the freq of the line voltage to change speed. Did you replace it somehow?

I use 1/4" and 1/8" bits to do just about anything. Thats within the limits of the depth of the bit. The CAM package I'm using has the option to cut inside or outside the profile, or completely inside the profile. On a circle it simply plunges into the center and sprials out to the diameter. I found that routing holes is much better then drillig because you only need a bit smaller then the hole and changing size slightly is no problem. Also no chipout and drill bit walking.

So the answer to your question is software.
Dean

Dean,

Thanks for info. I like your idea of using a 1/8" mill to spiral route holes. I'll experiment with that.

My 690 doesn't have an internal speed control. It is a single speed unit. I am using a multi function router board that has a VFD built in and uses the PWM from Mach3 to control it (as far as I know). The board is a C33 from CNC4PC.

James

[Dean448]

My mistake... for some reason I was thinking about the 890.
Although I'm not sure I would try to code the sprial out by hand let me know if your interested in seeing the gcode by providing the parameters of the bit & hole size.
Dean

[jharvey407]

Thanks Dean, but I don't have any problems with the programing, I was just wondering what methods were available for drilling holes.