Router Bits and EndMills: Pictures, Descriptions, and Uses - Page 2

# Thread: Router Bits and EndMills: Pictures, Descriptions, and Uses

1. this link was posted on another forum... It might be of interest here ...

2. A noob question about the down cut tools...

I always thought down cut tools were limited to edge finishing because they push the chips down into the work. Is that not the case?

3. Originally Posted by TrickyCNC
this link was posted on another forum... It might be of interest here ...

Pretty good resource. For many DIY machines, it may not be possible to achieve the reccomended feedrates and spindle speeds due to certain factors, but you could still get pretty close to the recommended chipload.

Usually however the chipload is known, and then the feedrate could be calculated for a given spindle speed, derived from the chipload formula:

feedrate = spindle speed X chipload X number of flutes
chipload = feedrate / (spindle speed X number of flutes)

The other useful formula is for SFM, or Surface Feet per Minute. Some manufacturers will list their tooling's capacity in this way, calculated as:

SFM = 3.1416 X RPM X bit diameter / 12

Yet another one is the MRR, or Material Removal Rate, but you'd need the IPT, or Inch Per Tooth feedrate to calculate it:

IPT = feedrate / spindle speed (rpm) / number of flutes

MRR = spindle speed X depth of cut X width of cut x IPT x number of flutes

So for example, in the BMX chain sprocket video above, pocketing the openings between the spokes, my parameters are:

My chipload is .0027, SFM = 850, IPT = .0027 and MRR = .315in^3/min

4. Found this online calculator which makes it easier...

Milling Formula Calculator

5. Originally Posted by ftkalcevic
A noob question about the down cut tools...

I always thought down cut tools were limited to edge finishing because they push the chips down into the work. Is that not the case?
The chips will still eject, though not as efficient as an up-spiral. They work fine for mortising and pocketing operations. If your work is held down tight to the spoilboard, though vacuum or clamping, you can achievev a decent finish on the bottom. A downspiral can also be beneficial when cutting thin stock, as it can prevent the stock from lifting.

6. Originally Posted by ftkalcevic
A noob question about the down cut tools...

I always thought down cut tools were limited to edge finishing because they push the chips down into the work. Is that not the case?
The deeper the depth of cut, and smaller the bit diameter, the more likely chips are to pack into the cut. But if you take shallow cuts, you'll get much less packing.
The other day I cut some red oak with a 1/4" downcut spiral, .05" per pass for 3/4" thick parts. 400ipm, and when the parts were finished (.70" deep), there were no chips in the cuts.

Downcut bits will tearout much less than upcuts when cutting solid wood.

They'll leave a clean top edge even when they get very dull. Because of this, you can get a lot more life out of downcut bits.

They'll help to hold parts down. On 3/4" parts, I can cut .745 deep without going though, because the bit is pushing the material down. With an upcut bit, it would lift the material up and cut through, allowing the part to move.

7. When I use a 5/32" Centurion Tools down spiral on 3/4" pine, oak or baltic birch ply, I get severe packing. In my case it actually kind of helps as then I can cut all the way through in a single pass without the parts moving. That saves me from sanding the edges from the onion skin or sanding the parts down.

I have had people tell me also that I cannot cut 1/2" deep in a single pass with a 1/8" down spiral bit. We do it day in and day out at 150-175 IPM with the ones from Centurion Tools. I have yet to find another bit to be able to do the same without breaking.

Those are my two main bits that I have experience with.

Sean

8. Thanks guys. I always learn a lot from this forum.

And CURSE YOU ALL! Now I'm going to have to go buy more cutters to play with.

9. I just picked up this 2 inch Magnate Surface Planning bit from amazon and it works really nice to surface your spoil board and or planning other boards. Cheap too. They also have a 2.75" bit as well.

http://www.amazon.com/Magnate-Surface-Planning-Bottom-Cleaning/dp/B0006B0QXE/ref=sr_1_27?s=power-hand-tools&ie=UTF8&qid=1332934788&sr=1-27]Amazon.com: Magnate 2706 Surface Planning ( Bottom Cleaning ) Router Bits - 2" Cutting Diameter: Power & Hand Tools

I picked up some single o-flute, and 60* v bits from Magnate as well but have not used them.

10. Originally Posted by vtx1029
I just picked up this 2 inch Magnate Surface Planning bit from amazon and it works really nice to surface your spoil board and or planning other boards. Cheap too. They also have a 2.75" bit as well.

Amazon.com: Magnate 2706 Surface Planning ( Bottom Cleaning ) Router Bits - 2" Cutting Diameter: Power & Hand Tools

I picked up some single o-flute, and 60* v bits from Magnate as well but have not used them.

That is cheap... never seen a spoilboard cutter like that, might have to give it a shot.

11. Louie, some of your bits look like they have been around for a long time.
Which leads me to my question, is it worth sending my dull bits out for resharpening?
I notice BamCarbide offers this service for 9.00\$ per bit for 1/4"
I was thinking if I had a few bits to ship at once this might be worth it.

12. Originally Posted by Drools
Louie, some of your bits look like they have been around for a long time.
Which leads me to my question, is it worth sending my dull bits out for resharpening?
I notice BamCarbide offers this service for 9.00\$ per bit for 1/4"
I was thinking if I had a few bits to ship at once this might be worth it.
I kept a lot of my older bits from the hand held days. You can easily hone them with a fine diamond whetstone, on the flats (do not hone the relief angle). This is how I do it. I don't machine my stuff to glass-smoothness, rather I prefer to do the final little bit by hand. I think I had that 1" core-box for about 18 years...

And yes, resharpening is WAY cheaper than buying new...

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