Recommendations for HDM end mills / surfacing bits?

Hi everyone,

I’m looking forward to my HDM shipping in a week or so. As you know, it uses ER-20 collets, which will go up to about 0.5 inches.

I’m planning on using the HDM on a variety of hard woods, polycarbonate, acrylic, aluminum, and possibly brass.

I’ve done some research on various end mills and surfacing bits, but am pretty lost in terms of what I should get. I’m interested in your recommendations on this. I understand that the first few bits I use will probably have some issues as I go up the learning curve.

In terms of specific applications:
Wood: smooth bevels, carving out large sections up to ¾ inches deep.
Polycarbonate / acrylic / aluminum / brass: carving out “square” holes about 1" in L/W, beveling outside corners.

I’m interested in high quality finishes that require minimal post-processing.

Would sincerely appreciate any help on this, along with any of your tips / tricks for success.

Thank you.

the shapeoko ebook has a section about endmill types:

with a recommended starter set at the bottom of the page

But basically:

  • for wood you will want a couple of upcut square endmills, and a couple of downcut ones (for clean top edges), in a variety of sizes (1/4" and 1/8" for sure, on the HDM you can larger tooling too to destroy wood, but you will need solid workholding)
  • for bevels in wood a 90° vbit is useful
  • for plastics, O-flute (“O” not “0”) endmills shine, dedicate a few to plastics (i.e. don’t cut anything else than plastics with those endmills)
  • for aluminium, start with ZrN-coated single flute endmills (much more tolerant to beginners mistakes than high-flute-count endmills). Then you will have many options down the road, some of which will require specific toolpaths.


Thank you for your terrific reply. I had no idea there was a shapeoko ebook. What a great source of knowledge. It’s also extremely well organized and very well written. I appreciate the heads up about that resource.

The various types of end mills is also a great help. I went through the ebook chapter on this and found it to be very helpful.

Do you have 1 or 2 different vendors that you go to for purchasing? Who do you recommend?

Thank you.

I have a mix of Carbide3D endmills, Amana endmills, random ebay/amazon endmills, and a number of specialty tools from a local French supplier (
My favorites are Carbide3d vbits, amana single flute endmills, yonico downcuts, but really anything decent works. I’m sure folks here will be able to provide good local options for you to consider.


I use 2 options depending on the job. Both I wouldn’t do deep cuts in harder materials. If you need to remove a lot of material or go deep, 3/8" tooling is the sweet spot for deeper cuts and using strategies like adaptive clearing. Surfacing implies low depth of cut and concentrating on a good finish.

1/2" 2 flute endmill. For deeper surfacing (0.050"-ish DOC) this is my choice. The ER20 Collet will use up to 1/2" and you can remove some decent material with that as long as you keep the power of the spindle in mind and don’t go too deep combined with a larger stepover.

If I want a really good finish on metals, I use the following. You have to have your tram dialed in and I do a max of 0.020" DOC. I don’t use above 10,000 RPM. But it gets great finish when dialed in.


I’m just starting out myself, but I’ve been using Speed Tiger cutters. So far all I have cut with them are softer woods and plywood. They are made in Taiwan and appear to be of good quality, but they are still cheap enough for me to learn with.
If you are just starting out, using the cutters Carbide 3D sells has the advantage of the tool libraries are already there. This saves you the trouble of configuring them.

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I like my white side 1" surfacing bit for wood but I bought it before the Mcfly came out and I like having replaceable inserts if I have issues and ruin a cutting edge so if I ever need to replace my WS bit I will look into a insert style cutter. Preferably with a 1/2" shank for more rigidity.

I love my Bush machine 1" face mill for aluminum and run 6mm ebay china single flutes with great success in 6061.

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Following this with interest :slight_smile: I’m used to wood bits and some plastic but aluminum is still pretty much a mystery to me, and I have an order prepared but haven’t pulled the trigger yet. Decisions between single or triple flutes etc. I already have 274Z and 282Z that I had bought for my Nomad and didn’t get to use yet, but nothing bigger.

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Thanks for your reply. This was very helpful.

I didn’t know about inserts. I found this on Amazon.

Seems to have great reviews. ½" shank, 3" cutting diameter (wow!), runs at 12K RPM (perfect for HDM), and has inserts. I bought the extra inserts for $30.

I went shopping this afternoon…

Amana 51411 O flute for acrylic / polycarbonate
Whiteside compression bit, up cut bit, and down cut bit in ⅛" and ¼" radius
Amana 51373-Z O flute for aluminum (ZrN coated)

Then these guys:
uxcell straight flute taps in M4 and M6 sizes. No idea whether it’ll work on my HDM, but figured I’d try.

A 3" cutter is going to need a good amount of care / caution to run without issues. I hope you have a 2.2kw spindle if not take very small step down passes only in wood or other soft materials and make sure work holding is on point or it will become a high speed pitching machine. Please be careful and have a safety barrier of some sort.

I have had 2 pieces get flung by a 6mm single flute over the past few years. One that came out of soft jaws and got thrown into the polycarbonate door on my HDM enclosure and one that got sent across my garage like a ninja star from my So3 before it had an enclosure. Both were 6061 aluminum and while only 1 was going fast enough to cause a serious injury the possibility is always there.



Thanks for that safety tip. I didn’t realize that the 3" cutter could pose such serious safety issues.

I’ve purchased a smaller 1 ¼" cutter until I get used to the machine and can build a proper enclosure for it.

Much appreciated.

I have the Amana RC-2250 which is 1.5". So far I’ve only used it once to surface a MDF wasteboard and it worked very well. Here’s my tool settings:

1.500 in
Flute Length:
0.390 in
Included Angle:
Num Flutes:

2D Cutting Parameters

Feed Rate:
75.0 in/min
Cut Depth:
0.020 in

3D Cutting Parameters

Feed Rate:
75.0 in/min
50.0 %
Finish Allowance:
0.020 in

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