# Anyone Using Endmills in Their Router?



## Gatsby1923 (Oct 22, 2009)

Well I need to cut a bunch of deep large mortises in my upcoming workbench project. I have been experimenting with some methods because don't want to invest in a hollow chisel mortiser right now. Chomping out a 3/4X2-1/2×1 to 1-1/2 inch deep mortise by hand is not going to work, even when drilling out the bulk of the wood I am not happy. So I am going to go for using my plunge router and a jig to do so.

Here is my issue, Up cut spiral bits especially larger ones are very very expensive, and being a tool maker by trade i know I can get solid carbide end mills for a fraction of the cost, HSS ones for a fraction of that price.I did some searches and know some people on this website as well as some others are doing this, but they give little details. Do I got for 2 flute, or 4 flute? Would a cutter designed for a softer material like Aluminum cut better? My guess is a two flute carbide or cobalt endmill maybe a specialty aluminum bit because of it's higher helix to give better chip clearance.

Dave M.


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## Ampeater (Feb 21, 2008)

Dave

I have been using endmills in my router for quite a long time and they work great. You should use a 2 flute endmill and carbide and cobalt endmills will last longer. Going down 1-1/2" should be easy.

Make sure that the plunge router/endmill combination will work well together. By that I mean that the length of the endmill must be long enough to reach the bottom of the mortise and short enough to be above the base of the router when setting up the cut. Also, the cut-length of the endmill needs to be taken into consideration.

The best way to cut mortises is to plunge all the way to the bottom of the mortise at both ends of the mortise. Then remove the center part of the mortise 1/4" at a time. This will help to keep the endmill from overheating

I usually buy my endmills from ebay and I use 1/4", 3/8" and 1/2" diameter.

You can order adapter bushings here that will allow you to use 3/8" endmills in the router.
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bushing_ball_bearings.html

Ralph


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## JohnGray (Oct 6, 2007)

Ampeater,
Thanks for the information.
John


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## KayBee (Jul 6, 2009)

Cool, learned something new! Thanks.


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## mynoblebear (Nov 22, 2009)

That is what I would do keep it cheep and simple and move forward with the project.


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## scrappy (Jan 3, 2009)

Thanks for the info.

Scrappy


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## WilliamEarl (Dec 7, 2009)

One more thing to consider. Spiral end mills are sold in 'up cut' and 'down cut' patterns. This refers to the direction the waste will be pushed by the flutes. For mortises in wood I use an 'up cut' pattern to pull the waste up out of the mortise. I undertsand the 'down cut' pattern is used when you have a laminate top to avoid causing surface cracks.I agree whole heartedly with the advice about removing the mortise center section a 1/4" at a time. The end mills have no cutting edges along the flutes so they do not plow like a conventional bit.

These are a nice lower cost alternative to conventional bits that have down cut carbide blades added to the lower end.


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## MrRon (Jul 9, 2009)

I asked that same question the other day over on another forum. The reply was to use a brand new carbide endmill that hasn't been previously used to cut metal. I questioned speed and the reply was he uses it in a vertical mill at 2000 rpm with good results. I think end mills work better on hard woods than soft.


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## Gene01 (Jan 5, 2009)

Question for WilliamEarl and Ampeater,
If the flutes don't cut, don't you end up with the same type of ragged hole as you do when using a Forstener to hog out the mortise?

Another question. Do you use a VS router?


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## WilliamEarl (Dec 7, 2009)

I don't use a VS router. Actually my favorite router for this job is my Makita 3 HP with the rectangular base. This dates back to about 1983 and is a real workhorse.

When I take the plow moves in small stages like Ampeater describes I get a nicely finished mortise. Much nicer than when I use my Delta hollow chisel mortiser.

One final thing I do is be sure I only route the mortise to within a 1/4 " of the ends. I usually square the mortise with a mortising chisel and need that much material to support the chisel cut so it doesn't drift. From there it's a quick trip to the table saw where I use my tenoning jig.


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## Gatsby1923 (Oct 22, 2009)

I ordered some HSS Endmills from Enco about a week ago and they arrived yesterday so I undertook some experiments. The reason I picked HSS instead of Carbide is I wanted to know it would work before I payed for Solid Carbide. Also my first project I will be cutting this way only needs 4 mortises and I am sure they will survive that long.

I used a Variable speed router and the flutes do cut.

I started off with a standard 2 Flute center cutting mill with 1-1/2 inches of flute The material was Red Oak. Because of how the stops are on my plunge router I roughed the mortise about a 3/8 deep with a series of plunging passes. This gave the chips a place to go. Then I followed by a cleaning pass, and from then out I would plunge at one end of the mortise, and cut to the other. I did this to a depth of just under 1-1/2. The was some minor burning, mostly while i was figuring out a speed and feed. The endmill survived but with very slight brown burning at the very tip.

My second mortise was with a 2 flute specialized Aluminum cutting end mill with 1-1/4 flue. The helix is different on these and it should have give better chip evacuation in a softer material. It did seem to cut better especially on my initial plunge passes. Though once to depth the effort seemed the same. The Endmill also survived but with seemingly less burning to the tool tips.

Both mortises came out clean and I was happy with the results. I think I will put down the dough for some solid carbide mills now I am sure this will work.

Dave M


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## 33706 (Mar 5, 2008)

I'd like to add that not only can you use endmills for machining wood, but you can also do stuff with endmills in your router for aluminum fabrications.
I once bought a 12" X 24" X 3/4" thick aluminum plate at a salvage yard, made of 6061 Aluminum. This is the alloy preferred for quickie machine-shop jobs for making miscellaneous parts.
Anyway, with a 1/4" endmill, bosch 2 HP router and a speed control, I carefully nibbled away a 3/4×3/8 groove to accept a standard miter gauge, and built a small spindle shaper using the spindle from an old AMT kit. I then cut some elongated 1/4" holes for the fence adjustment. Then I used a Lenox 1 1/4" carbide hole saw for the spindle opening. It looked as good as factory-made! Just feed slowly, use cutting oil, and make sure your guides are clamped securely. Be sure to wear a face shield, and *Be Careful!*


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## mpientka (Dec 10, 2009)

For deep pockets I've occasionaly use my 4-flute metalworking end mills in my router. I use the slowest speed on the router and don't have any problems.


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## RJones (Jan 9, 2007)

Here's a resource for reasonable router bits. 
http://www.centuriontools.com/router_bits_toolcase/index.html?cart=12608842573736294

I use many of these in my CNC with excellant results.


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