3/4" Straight Bit?

A project needs a large amount of clearance in a pocket. My biggest end mill is 0.25". I’m considering using a standard 3/4" carbide straight bit intended for normal router work. Got a couple of questions.

  1. Why shouldn’t I? Is there a compelling reason not to?
    Assuming no to the above:
  2. In the Aspire tool database, the 0.25 has a feed rate of 100 IPM and plunge rate of 30 IPM with a depth per pass of 0.125 (1/8). When I tell Easel I want to use a 0.25 (which has to be entered as “Other”) it chooses a feed rate of 30 and plunge rate of 9 with a depth per pass of 0.028. Easel tells me it chooses these figures based on regularly updated industry information. So, which one is closer to right for a 0.25, and how would you extrapolate that to a 0.75? Obviously, plunge rate is a major consideration.

Is the 3/4" bit meant for plunging? That’d be a big concern for CNC usage. You’d have to ramp in your cuts instead of straight plunging.

I doubt it. From what I’ve seen so far (which isn’t much) I believe Aspire will factor the plunge rate into the toolpath.

Edited to add:
Yes, it will. In fact, there’s a feature in the advanced toolpath options that lets you set that value.

I tried this recently , I suggest doing the detail pass first then clean out , I did clean out first on my last project with a 3/4" bit and it tore out some of the detail and small areas whole pieces of the project went flying , I re ran the project but did the detail pass first and it came out great.


This one doesn’t have blades on the bottom. Just two running up the sides. It’s an inch high.

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What your looking for is a “center cut” end mill. If it don’t say that then you have to look a lot closer to the speck’s and pictures.

Phil, I have to disagree on this one. I am not X-carve experienced but come in with 50 years of woodworking background. I also probably own every woodworking power tool known to man! I say that in jest - I just love power tools.

In my experience, many router bits will plunge if forced. Some won’t plunge no matter what you do but will make a lot of smoke. :flushed: Some if correctly designed will plunge well but they need to have a cutting edge running all the way across the bottom - not leaving an uncut portion in the center.

I have seen some without full cutters claim they are plunge bits but what they do is cut the sides but chew the center down some and then depend on lateral movement to clean up the mess. Stick one of those in a plunge router and just plunge a hole 3/8" and lift out. Look at the cut and tell me it truly plunged. Take one with a cutter all the way across and do the same thing. Clean cut - that is a plunge bit.

I know - with our X-Carves we don’t do deep plunges with these and can often get away using them but in my book that doesn’t make them plunge bits. Most quality bit manufactures will state if their bits will plunge. Usually if they don’t say they will - they wont do or at least not well.

Just my 2 cents.

For this one with blades only on the sides, I set the ramp plunge to 3" on a 1/8" depth of cut, as shown above. I think with it easing down 1/8 of an inch over 3 inches, no harm was done to bit or wood. Obviously, a plunge bit is preferable and I’ll add one to my collection soon.

Question: this bit calls itself a plunge bit, and yet doesn’t have a cutter across the bottom. What’s up with that? Comments?

See how the bottom (top in picture) has a slight helix to it? That’s how it can plunge.

This style of bit are very common. Often found at big box stores. They won’t really plunge but you may get away with very shallow cut.

I use these plunge bits all the time. No deeper than .06 at a time. They just dont leave a very clean bottom so I go back through with a 1/8 Inch bit to clean it up