Newbie drill bit Question

[wvmudder1]

OK, I'm ready for the flaming, but what are silver and deming drill bits? Do they have a special prupose? I need to buy a set of bits that go to at least 1inch for my hydraulic steering ram. I found a HF set for $49 with 1/2" shanks, which would be perfect for my drill press. Thanks, Dave

[PTSchram]

Silver & Deming are credited with making large diameter bits with smaller diameter shanks. Kinda like Jo blocks, they've kept the name.

[DrMaserati]

Here is a quote from the history of the Silver & Deming Manufacturing Co.

"Silver & Deming apparently invented the large-size twist drill bit with a turned-down shaft so they can be used in a chuck smaller than the bit's cutting diameter. They did not patent this idea, so the idea was quickly copied by others, but these bits are still called 'Silver & Deming drills'."

[Flashover Mfg]

They are typically 1/2" shank and a standard length (6"?) rather than length increasing with diameter.

[NIB-98TJ]

ENCO has a set on sale right now that I ordered yesterday. I believe it was 9/16" to 1-1/32" by 32nds for about $45. They are Chinesee and may not be worth a crap.

NIB

[PTSchram]

S&D bits are one of the few things I absolutely will not go cheap. If you try to sharpen one and get it worng and it grabs, it WILL rip the drill from your hand and spin it around with lots of force. Of course,really sharp new bits will do similar!

[frankenfab]

Home Depot opened in town, putting True Value Hardware out of business. I picked up some US made S&D bits yesterday from 5/8 to 1 inch at 50% off. They run $20 to $30 each normally. I also scored some bi-metal holesaws. Finally, Wiss aviation snips, complete set (right, left, and straight) at $7 each.

:grinpimp:





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[jnutter]

ENCO has a set on sale right now that I ordered yesterday. I believe it was 9/16" to 1-1/32" by 32nds for about $45. They are Chinesee and may not be worth a crap.

NIB

I've been using a set of those cheap Enco made in China SD bit sets in my home machine shop for a few years now. They are great. I use the crap out of them and I haven't had to re-sharpen one yet. They mostly get used on the mill, but sometimes they find their way into the cordless drill. They work good in both. I've filled a 5 gallon pail with chips from those bits a least twice now.

The key is to drill a pilot hole that is at least as big as the web on the bit. The center of the tip just won't cut well, no matter what you do - although a little web thinning would help if you absolutley couldn't drill a pilot hole. Part of the reason is the geometry of the center of the tip and part of the reason is becuase the SFM approaches zero at the center of any spinning bit or end mill.

Also, I always run them at 70 SFM at the perimeter and I'm not shy about the feed. Chips from these bits should look like the ones in this photo: http://members.tcq.net/jnutter/machineshop/photos/photo3.jpg And as you can see from the photo - I run them in a collet when I use them on the mill.

All of this stuff helps them work better and last longer.

[NIB-98TJ]

I've been using a set of those cheap Enco made in China SD bit sets in my home machine shop for a few years now. They are great.

Well, I hope these drill bits work for me as well as yours did.

I have a question for you. I don’t have easy access to a big mill like you have. I have a medium size floor drill press. I need to drill several 1” holes through a piece of 5/8” thick flat bar (mild steel). My plan was to progressively drill the holes out in 1/16” steps until I get to 1”. But someone else is telling me I should just drill a 5/16” pilot hole and go straight to the 1” bit. What do you think?

NIB

[jnutter]

I usually hit it with centering drill first, then the 5/16 pilot drill and then right to 1".

The centering drill is optional. It's purpose is to keep the next bit from walking when you start the hole.

Feed it hard! The only reason those chips aren't several feet long is becuase I back out on the feed for second to break them off before they start to hit me. If you are making little flakes, something isn't right.

[PTSchram]

Well, I hope these drill bits work for me as well as yours did.

I have a question for you. I don’t have easy access to a big mill like you have. I have a medium size floor drill press. I need to drill several 1” holes through a piece of 5/8” thick flat bar (mild steel). My plan was to progressively drill the holes out in 1/16” steps until I get to 1”. But someone else is telling me I should just drill a 5/16” pilot hole and go straight to the 1” bit. What do you think?

NIB

Pilot holes should not exceed 1/2 the final hole size-per the old codger machinist I used to work with.

If you're using them only in a drillpress, you'll probably be fine with the Enco stuff. I have used all manner of Enco stuff and the only thing I was less than pleased with was an adjustable reamer. Even it was inexpensive enough that I wasn't overly upset.

[Travis Waldher]

Chips from these bits should look like the ones in this photo: http://members.tcq.net/jnutter/machineshop/photos/photo3.jpg

Chips from any steel drill bit should look like that.

If they don't you are running the RPM's up too high causing excessive heat which dulls the bit faster. It also takes longer to cut.

Once you got the RPMs and right amount of pressure figured out, you should be getting those nice long curly-q's.