Through Boring Melamine

[bstern]

I have been using 5mm through bore bits to bore through 3/4 melamine at 12K RPM and 1 IPS plunge speed. Works great no chip out either side.

I am planning on adding the Shopbot Air drill and it will runs at 3350 RPM. With current tooling this will chip out until I run at .2 IPS. With lots of holes to drill it will slow me down too much unless I can speed up the plunge.

Any suggestion on tooling that can handle the slower rpm without chip out at faster plunge speeds??

Bob

PRS Alpha

[bill_lumley]

Bob , not clear on the question .. Are you drilling your 5mm holes today with the same bit that you cut with ? I am assuming that it is a 5mm downcut bit you are using . Why don't you go to a 5mm drill that is used in line boring machines to run in the air drill and stay with your current cutting bit in the router/spindle . The line boring bits are brad point and should do fine at the RPM required and faster plunge speed .. Maybe I have missed something though ?

Bill

[henrik_o]

In line borers through holes are usually bored using special v-bit drills, I have not tried them myself in melamine but have heard from others that as long as they're razor sharp they do very well. The plunge rate on a line borer is usually around 1-2IPS (it is on ours at least) so they should work for those speeds.

One example here;
http://www.amanatool.com/boring/313004.html

[bstern]

I am currently using the through bore v drill bits.
At 1 ips I get some chip out at 3500 rpm. (12K works great at 1 ips)
Brad points blow out the back when though boring.
I am looking for a drill bit that would not chip out melamine at 1 ips plunge at 3500rpm.

I am having Morris tool make me a special 3 flute v drill bit. I hope they will work but they are a bit pricey at $42.00.

Henrick, do you know what RPM the line borers run at? I will send you some pics of the 3 drill aggregate as soon as I can slow down long enough to take some pics. It runs at 3500 rpm as well. I am having to slow the plunge to .2 ips when the tip of the drill is in the melamine top and bottom of the melamine slowing production considerably. Need solve this for the air drill and the 3 drill aggregate.

[henrik_o]

I don't have an official RPM but I will hazard a guess and say our Bilek does not run as fast as 3500RPM. I base that on how it sounds, so take it for what it is; a guess. Probably 2000-3000 range.

Pictures would be nice, when you have the time.

For your situation here, I would call the manufacturers of a few brands of drill bits and ask for clarification. I know certain bits are marketed as being able to through bore melamine, so they must have something to back that up.