Need Help!- parabolic drills speeds and feeds

[KENWILD1]

im trying to drill a .201 hole down 3.5 inchs through 6061 alum. on a hass vf2.
it is able to spin at 10000.

we also have a milltronics dinosauer that will only spin at 2200 with a push lol

i have no idea where to start with the speeds and feeds
and also do i need to peck with flood coolant
any help would be much appericated
thx

[BobWarfield]

Well that certainly is a long skinny hole, Ken!

I did a little research and found this page had some interesting answers:

http://www.precisiontwistdrill.com/t...?image=contact

I programmed all that into my G-Wizard Machinist's Calculator. For your case, I get the following:



That would be the feeds and speeds based on Precision Twist's recommendations. As you can see from the image, peck drilling is also recommended!

I don't know how well that deep hole is going to work, but that's where I'd start. Another thing I have seen recommended is using multiple bits. Start the hole with a stub (screw machine) length bit, and drill to its max depth (leave flutes exposed!). Then go to a jobber length. Finally bring on the parabolic.

This is right at the limit of what Precision Twist talks about.

Cheers,

BW

[Delw]

I am doing a 3/8" parabolic drill at 35IPM and 7000rpms peck every half inch on my haas.
on my hand lathe I am running 1800rpms and feed it as fast as the tailstock will allow me to by hand. in 2.75" depth cuts like butter.
I found on the parabolic drillsI can get about 2-3 times the feed as a standard 135º drill split points but the rpm needs to be slower or you get chatter. at the start. also keep your center drill hole small( just enough to center the drill.

I only center drill never pre drill a hole, if i do the chips build up a rats nest and the drill tends to walk.

[KENWILD1]

THANKS

I DID SOME RESEARCH MYSELF AND CAME UP WITH 2280 RPMS
AND F11.4 NO PECK
GOING TO HAVE ANOTHER SIP OF COFFEE AND THEN LET HER RIP

[keithorr]

I wouldn't peck if I could avoid it. Negates the value of parabolic flutes which is fast chip clearance and improved access for coolant.

I would custom grind the drill if possible. The stock grind is just that; an all around standard geometry with no consideration for specific material. If you can grind the relief angle to match your feed/rev, you'll get a smoother cut by allowing the material to support the lip; using the heel as a bearing surface as you feed to avoid digging into gummy material. I use an old Darex grinder which is a nudge better than black art.