Author Topic: Drilling with a spade drill (Read 1024 times)

Cat Whisperer · « **on:** October 06, 2005, 03:20:53 PM »

This is new to me, haven't seen anyone else do it (other than a few pix here) and so I'm learning.

Material 303 stainless, 1-7/8 diameter with 1Â” spade drill.
I hooked up the coolant to the drill bit and (once it was into the metal) turned up the flow. Speeds were from 470 to 1250 rpm, feed by hand (no automatic feed on this one). Light cuts cleared well, medium cuts had to be cleared every 1/2" or so of cutting. Drill and bits from separate purchases on Ebay. Under $21 for the drill and a buck or two for each bit.

The bit itself, in an 11Â” long holder.

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Cutting chips like this would not flush.

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Cutting chips like this would flush continuously.

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kappullen · « **Reply #1 on:** October 08, 2005, 08:05:46 AM »

Cutting speeds for steel were considered to be 60 feet per minute with a hss cutter, and 300' with carbide.

These days things are increased, due to better grade tooling and coatings.
The flow of coolant you are running will increase things somewhat.

Two hundred and fifty would be a good starting point for 303.

You were succesful with minimal tool wear so I can't argue with success!

Keep up the good work

Kap

Cat Whisperer · « **Reply #2 on:** October 09, 2005, 01:27:59 AM »

Quote from: kappullen

Cutting speeds for steel were considered to be 60 feet per minute with a hss cutter, and 300' with carbide.

....

Thanks Kap. Golly gee - speeds and feeds. I GUESS I could have LOOKED that up in my Machinery's Handbook! I am not a machinist by trade (obviously).

Refresh my memory. I can figure the speed from the feet/minute on the outer circumference of the tool and work back to the rpm of the work, but what is the recommended feed?

I am going to do something to increase the pressure of the coolant to clear the chips better.

AND I am going to build a better fixture for aligning the tooling to the axis of the work piece.

guardsgunner · « **Reply #3 on:** October 10, 2005, 01:48:08 AM »

I kind of been wondering why nobody had mentioned using spade bits for doing golf ball mortars. regrind 2 to bore dia. then grind the .8?? r on to put the rad. in the bottom. would be a fast way of doing it.

Cat Whisperer · « **Reply #4 on:** October 10, 2005, 05:12:03 AM »

Quote from: guardsgunner

I kind of been wondering why nobody had mentioned using spade bits for doing golf ball mortars. regrind 2 to bore dia. then grind the .8?? r on to put the rad. in the bottom. would be a fast way of doing it.

There may be an issue with keeping it centered/chatter. I tried (in my limited experience) opening up a 1/2" hole to 1" with a LOT of chatter. One of the machinists here a work recommended not to even try it. YMMV.

GGaskill · « **Reply #5 on:** October 10, 2005, 08:43:40 AM »

Since there is no body on the spade drill to keep it centered, it relies on the point for centering. I suppose you could have a small pilot drill but it seems to work best to drill the whole hole with the spade bit.

Allied Machine & Engineering is a good online technical resource.