Replies

1. 
   Malicair | Apr 17, 2003 03:30am | #1

   Art,

   That depends.... (oh boy here comes my machinist experience)

   There are three things to consider in when making cuts with tools.

   Material: With harder and more abrasive materials you need stronger cutters. Carbide is for very hard or abrasive materials or in situations that you want long cutter life. Many people will say different but carbide can't take as sharp as an edge as can HSS (High Speed Steel). But the huge benifit of Carbide is that it can hold an edge MUCH longer than HSS. The big plus about HSS is cost! Carbide is just so expensive that unless you really need it it is much easier on the pocket to use HSS end mills. Especially for woodworking!

   Speed: The harder or abasive the material is the slower the speed. Along with the larger diameter of the end mill the slower the speed. This get's into surface speed and heat generated by the material cutting.

   Feed: This refers to the "chip" load on the cutter, "how thick of chip are you cutting?". This goes hand in hand with the speed of the cutter. The slower the speed the slower the feed.

   Realisticallly because we are working in wood you don't need to consider most of these problems because the abrasiveness of wood is so far below steel or aluminum. Although you may generate enough heat in cutting the wood it is very unlikely to dammage the cutter.

   What type of wood are you using? If it is a common hardwood or softwood. (cedar, fir, pine, ash, oak, maple, walnut, etc...) and doesn't have alot of silica and or oils in the wood then you can run a pretty fast RPM (surface speed).

   So let's give you a bit of an example... would I worry about turning 10,000 rpm on a 1/2" HSS end mill doing a plunge cut to a depth of 1-1/2" in hard maple? Not at all as long as I can control the rate of cut and keep the chips clear. With any material when you cut to fast you run the risk of damaging the part or the tool.

   So in one sentence...

   Crank it up and let the sawdust fly!

   Regards

   Malicair

   
   

   ---

   Edited 4/16/2003 8:31:44 PM ET by malicair

1. 
   art | Apr 17, 2003 04:17am | #2

   Thanks, I will be using a 3/8 four flute end mill in red oak. Sounds like top speed on my drill press (3100 RPM) would be OK

1. 
   robkress | Apr 17, 2003 03:49pm | #3

   Art,

   I use metal machine end mills (4 flute carbide) extensively in my wood shop.  I find them to cut better and cost less than 2 flute woodworking end mills (maybe I just have a good source for them). 

   Anyway, here is how I run them..

   My 1/2" 4 flute gets most of the work that I do and I generally run it on the middle speed setting on my Portercable router (I'm sorry I have no idea what rpm that is... I never look or remember).  At higher speeds, I have found that the mill heats up too quickly and doesn't cut as well.  There is a balance between cutter speed and feed rate.... you know that you have the right speed and feed when....

   the feed rate mitigates (helps control and dissipates) the heat generated by the speed of the tool.

   So I try to work this balance.  Not paying attention to the above statement has caused me in the past to kill some cutting tools.  And rather quickly!

   Of course as the previous poster said, it all depends on the amount of stock you are taking out.... if you are shaving 1/32" then you can dial up the feed or speed much more than if you are taking a full cutter width at 1 1/2" deep.

   As for cutting slots with end mills, I have always found most success using a two stage cut.  So if I am cutting a 3/8" slot, I do my setup and cut the slot first with a 1/4" end mill.  Then, I replace the cutter without changing any table setup and recut with a 3/8" mill.  By doing it this way I have found that the slots.......

   have a better surface finish because I can turn up the cutter speed to the max on the finish dimension slot.  And when I do, I get very light little wispy shavings of wood.  Indeed a very fine finish.

   my cutters last longer.  Well I should say that my fine finish cutters last longer (they don't get heat damaged).  So I use old mills or roughing end mills to hog out the majority of the stock.

   the slot dimension is way more accurate.  And this is the big one.....  If I cut with just the finish dimension cutter, I find that the cutter flexes to the one side of the cut (of course) and the slot is then cut a little oversized.  By roughing with a smaller size and finishing with a second pass, this effect is very much reduced, to the point of not being measurable!

   the stock doesn't "fight me" in the cut when it really counts.  When roughing the first slot, if the piece moves around, there is no real problem.  Then when cutting the finish slot, the piece is much more under control (when it counts).

   And this method doesn't take much more time once you have worked out your work flow.  And the results are way worth it.

   Good luck

   Rob Kress

1. 
   art | Apr 17, 2003 05:44pm | #4

   Rob, what you say makes sense, no chip clearance problems on the final cut.  I'll Try it.  Thanks,  Art 

2. 
   RW | Apr 18, 2003 01:34am | #5

   For you or anyone else - any substance to the idea the putting an end mill in a drill press can pull the chuck loose? Chalk that up to heard from a friend of a . . . you know the routine.

   "The child is grown / The dream is gone / And I have become / Comfortably numb "      lyrics by Roger Waters

1. 
   art | Apr 18, 2003 02:29am | #6

   RW, don't know about that, but after posting yesterday, I had to try it. The entry hole was clean and required little effort to drill a 1/2 inch hole, However, when I raised the quill, it apparently grabbed the sides of the hole and almost tore the piece of wood out of my grip.  Being a slow learner, I repeated the operation several times to insure it wasn't a fluke. Conclusion, I'm going to rethink my strategy. Thanks for the responses.  Art

2. 
   robkress | Apr 18, 2003 06:06am | #7

   Rw,

   Yes, I do believe that using a router bit in a drill chuck can loosen it from the quill.  It would probably go something like this...

   Drill chucks are generally installed into the quill with a morse taper.  This is actually a very tight, sturdy connection for radial or torsional stress (perfect for drilling).  But the minute you add lateral stress, the connection is not so great.  And I can see this becoming even more prevalent when you add vibration. 

   As far as I'm concerned, using a router bit in this type of setup is the perfect way to demonstrate this whole scenario.  I can easily imagine a router bit setting up a vibration sufficient enough to release the chuck from the morse taper.

   Art, I didn't mention this in my post but I do belive that trying this slotting operation in a drill press is much less than ideal.  Two reasons off the top of my head that I can think of are....

   the drill speed is not quite fast enough for the operation of milling (especially by hand!).  And I think that this low speed could set up that grabbing condition that you describe.

   you would be working the piece between two fixed surfaces.... the drill press table and the tool coming down from the top.  This to me just seems like a recipe for trouble.  And speaking from experience (when I was younger and not so experienced), the last thing you want is to have "stuff" flying off the drill press at TOP SPEED!

   And I'm sure there are many other reasons that this is not the safest way to do the job.  If you do go ahead with the operation, please be careful and if you can use as many guides, stops, and guards as you can.

   Good luck

   Rob Kress

3. 
   Telemike | Apr 18, 2003 06:27am | #8

   Some of the other posts discuss why a drill press is inappropriate for this operation. 

   I would add that milling machines are built to deal with both axial (down) and radial (side to side) loads.  Drill presses are built only for axial loads and radial loads will destroy the bearings really quickly.  This difference explains why cheap drill presses cost $200 and cheap mills cost $1200.