Fly cutting -Speeds and feed- need help

[DrPatron]

Gentlemen:  I really enjoy reading the posts and have gained a lot  of info from you professional machinists.  I'm just getting my shop set up to ..keep me busy when I retire.  Just got a new Bridgepot Mill ( 9x42)  and am learning how to run it.  My Question today is- What speed and feed rates should I start with when flycutting Aluminum and steel?  Can I use the same formula that we use for mill cutters?  Any help appreciated, Thanks DrPatron

[sbwhart]

Can I use the same formula that we use for mill cutters?

Yes and No whist in theory its will be the same in reality the loading on a fly cutting tool is different its more of shock loading, so you have to let the machine and your common sence guide you if the machine sounds unhappy slow down a bit. Also you tend to use a fly cutter on nonferous materials, with steel the practice is to use a milling cutter.

Hope this helps, just give it a go.

Stew

[Miner]

The points Stew made were 100% correct. You have to listen to your mill. A heavy interupted cut does tend to hammer the bearings if you go for more material removal than you should. I do use them on steel but with pretty light depths and feeds of cut. A fly cutter isn't designed as a hogging tool but they do work well if their kept within the design limits.

I'm going to recommend a fly cutter that takes a round indexable carbide insert that works really well on my mill. Google KBC Tools, Go to page 398, Item no. 3-001-600 "The new generation fly-cutter". You get a real nice smooth cutting action. Unless you shatter the insert, Then you just rotate it a bit when the edge gets dull. You should get at least 6-10 fresh edges out of that one insert so it's really cost effective for the price of each insert.

Obviously the larger the diameter that the fly cutter is then the more you reduce the rpm, depth of cut, and feed rate. Even with multi tooth face mills hogging material on a Bridgeport it isn't recomended to go much larger than 3" in diameter.

If that's a brand new Bridgeport your a lucky man. Do you have power down feed on the head?

Pete

[DrPatron]

Thanks Guys for the tips, I'll look into the insert cutter.  The mill isn't new ,but might as well be. My son is a mechanical engineer who designs and builds the machines that make the parts, He got the mill from work, they never used it for milling , only laser indicating.  I has DRO, power feeds and yes it does have power down feed.  I may be posting a lot as I have so much to learn and so little time!  Thanks so much for the help-  DRpatron (AKA: John)

[Miner]

Ok John,
Great score on the mill. Here's your first tip you may not know. DO NOT USE THE POWER DOWN FEED FOR DRILLING. Bridgeport themselves I don't think recommend power drilling with drill sizes over or around 1/4". That power down feed is designed for single point boring when using a boring head. Since it was designed for that the internal parts are light weight. If you do use it with larger drills you WILL break it. Lot's of bucks to fix it.

I've got a book reccomendation for you that you really should buy. "Turret Mill Operation" by John G. Edwards ISBN 1-56990-273-9, You'll learn a huge ammount. It's the most detailed book I've seen about their operation. If it was me I'd buy the book and read thru it completely before running your mill again.

Pete

[DrPatron]

Pete-  Thanks for the tip, I'd probably used the down fdeed to drill a big hole and broke the bloody thing, Just got that book last wee k and am in the process of reading. I don't think I'll fire things up until I know what I'm doing Thank again-  John

[Miner]

John,
Your more than welcome, Glad you already have that book. You'll enjoy it.

Pete

[AdeV]

If you can get hold of a copy, I can very highly recommend Darrell Holland's "How to Run  a Vertical Mill" DVD series - 12 ~45min  long videos covering the Bridgeport mill in some detail. I watched them all several times through before buying my mill, so when it did turn up I already knew what all the levers did, and it almost felt familiar. The only thing I couldn't fathom was how he changed the speed (belt drive) so quickly.... and yet now, a couple of years in, I can do it almost as fast as him