DRill press ?

[JWD1312]

I"m going to buy a drill press since I burnt up two half inch drills building attachments . Is 240rpm slow enought for drilling and slow enought not to heat the bits up. Also where is a good place to buy or order one.Harbor Freight has one for $139.00 3/4 horse.

 

[chickenman]

speed depends mostly on the diameter of the drill
the smaller the diameter the faster the speed
250 rpm would be too slow for small drills
also not feeding the drill into the work fast enough can also burn them up
one of the ways a drill keeps cool is biting into cooler metal so not feeding fast enough jus heats up the metal in the work piece
also the use of a lubrecating coolant is highly recomended

 

[cleatus]

I would think that 250 would be great for 1/2" as my delta's slowest speed is over 500rpm and I have used it to drill 15/16". It realy was too fast, but I used a lot of oil.

 

[chickenman]

look at this page

web page

also this may sound counterintuitive but if the drill grabs when drilling take a piece of sand paper an lightly rub the cutting edges, sharp drills may be prone to digging in and grabing

also regidity of the setup makes a difference

 

[MadReferee]

I do all my drilling at 210 rpm on my milling machine. Most of the drilling is 3/8" to 1" holes thru metal stock that is 1/4" to 3/8" thick.

I use good twist drills for up to 1/2" and Silver and Deming bits for all work over 1/2". Liberal use of good cutting oil is always recommended. A sharp well lubricated drill bit will be easy to feed at 210 rpm.

The procedure I use for large holes (3/4" and above) is to first drill a 1/2" pilot hole and then use a 1/2" shank Silver and Deming bit of the correct diameter to complete the hole. This allows me to use a 1/2" collet in the milling machine for both bits thus keeping some semblance of accuracy.

 

[have_blue]

JW,

I have the 1 HP drill press from HF. It has 16" swing and 12 speeds. It cost $179, and weighs a hefty 187 pounds. It has been a great tool, and has been used very often for the 2 years I've had it.

 

[jmc]

Depends on what you are making your attachments out of. If it's mild steel, 240 RPM is well within a safe range under production conditions. (Rigid setup, coolant, & sharp, quality made drills) Handbooks show a maximum rpm for 1/2 drills @ 700 to 850 in mild steel.

About drills: If you get a chance, try 135 degree split point drills sometime. I noticed that Lowes carries them now but can't attest to their quality. The big difference from regular 118 degree conventional drills is that they have sharp cutting edges all the way to center. Most conventional drills have cutting edges that go not quite to center, leaving the very center(web) to wallow out a hole rather than cut a hole. The split point design cuts all the way to center and no wallowing is necessary.
If you have some serious drilling to do, buy good drill bits from an industrial supplier. I think some of the cheapy drills are designed to hold up in wood only. Good drills are cheap compared to your time and frustration.

 

[Farwell]

I drill quite a bit of stainless steel so I needed a very slow rpm. I had to put an adapter pulley set up on my drill press to get the rpm down around 40 rpm. I use quite a few bigger drills so I need the slower rpm. Never! Never drill with out coolant! Lesson learned in aluminum part where drill seized, broke and ruined the part. The same thing happened with a small tap. Try getting a seized, broken tap or drill out of something you really need, want or costs a bunch of money.

 

[slowrev]

Mad,
Just what is a silver and deming bit ? I bought an el cheapo set of bits at HF that say they are silver and deming. Not tried them yet, so I don't know if they are any good or not though.
Ben

 

[MadReferee]

Silver and deming drills are general purpose drills with a reduced shank to fit into a standard chuck, typically 1/2". Most silver & deming drills are 6" long with a 3" flute length. I have also seen them called blacksmith drills or prentice drills.

Here is something I found while searching the internet.

<font color="red">Silver & Deming Manufacturing Co.
Salem, Ohio

This company could trace its history back to 1854, although the "Silver & Deming" name does not date back that far. The titular heads were Albert R. Silver and John Deming. In the later history of the company, Emmor W. Silver was a principal; he was perhaps a son of Albert.

Silver & Deming was created in 1867 or 1868 after L. A. Dole had died, and Dole, Silver & Deming was renamed. In about 1874, Silver & Deming became Silver & Deming Manufacturing Co. In 1890, the company reportedly split, with one part becoming Silver Manufacturing Co.

Silver & Deming made a variety of machines that were primarily aimed at wheelwrights: hob-boxing machines, spoke-tenoning machines, etc.

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".
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