First test with 2 stage cut, a couple pretty obvious lessons learned

so new XC, cut #3.
I got added to the list for the 2 stage test cut.

this is the design: pretty simple

pass 1 was a 1/4" end mill, which I bought with the XC
pass 2 was a 1/16th Solid Carbide Downcut Fish Tail Spiral Bit using the 1/8" precision collet.

This is how it turned out:

some lessons learned:

I am cutting into some old lengths of oak hardwood flooring that we have laying around. I may need to stop doing that. The finish on the wood has very apparently completely dulled the 1/4" bit (on the third cut, no less) I have been using to clear the wood. It now looks like this:

as a result it both stained the cut and did not cut nearly as deep as it should have.
I wonder, do you re-sharpen these, or when they are done, are they done?
what should I look for in 1/4" end mills as clearing bits: are there better ones and if so which are they and how can you tell?
Also, I wonder if it is possible to use bits larger than 1/4" for clearing and flattening? I have a dewalt 611 as a milling head.

The precision 1/16th bit is totally amazing and cut extremely cleanly.
it was offset a bit as I am pretty sure I did not line it up properly when I changed bits and as a result had to clean a few edges.
is there a way to really ensure that you don’t mess up your spacing when you bit change?
The 1/16th is so tiny any little variation is immediately visible.

for cut #3, really happy with the circularity I am seeing, with minimal adjustment.
I have not done a runout distance adjustment in particular, as it has not really seemed necessary.
totally amazing machine, very glad I bought it…

It looks like you badly overheated the 1/4 inch tool. You either had the RPM setting on the Dewalt way to high or your feed rate was way too slow or both.

You should have the speed setting on the Dewalt at about 1 and your feedrate should be at least 6o ipm with a depth per pass of .06

I have been using easel defaults for feeds and speeds.
this sort of indicates I need to pay more attention to them:
are the defaults not trustworthy and if not,
is there an understandable guide on how to calculate them properly?

I have been using the Dewalt 611 at speed setting 1.

another edit:
looking at the easel project, it says
feed rate 812.8 mm/ min.
depth per pass 1mm

As others have said, it’s an overheated bit due to rubbing and not cutting. The bit relies on large chips to take the heat away so if it is spinning too fast for the feed rate then the chips are nothing more than fine dust and not able to carry the heat away.

As for the bit itself, it looks to be a goner… Once the bit gets to a color changing temperature it looses its hardness and dulls, so if you do sharpen it, it will go dull again because the metal has gone soft.

All of this being said, after you find the best feed/speed for your machine/bit/material you’ll find that bits can last a long time.

You guys are very helpful and I’m grateful as I guess I have a lot to learn about this.
One response here said 50 inch per minute, another said 60.
is there a rule of thumb? or is it all experimentation?


I read A guide to understanding basic Feeds and Speeds which was very good.
it said:
Here are the three possible ways to calculate chip load. You will need to know any two variables to solve the third (chip load, feed, and rpm). Typically you will know chip load and also know a RPM or a Feed that you wish to run out, and solve for the other.

If you know Feed and RPM………Feed Rate / (RPM x # of cutting edges) = Chip Load
If you know RPM and Chip load ………….RPM x # of cutting edges x chip load = Feed Rate (IPM)
If you know feed and Chip Load ………Feed Rate / (# of cutting edges x chip load) = Speed (RPM)

so I thought OK, I can calculate that, bit when I looked at the end mill I burned, so I could see what I did wrong,
the only data it comes with is:

Technical Data
Cutting Length 5/8 in
Overall Length 2 3/4 in
Onsrud Part #40-105
Best for Cutting Woods, aluminum

I looked up the part number online and could not really find a chipping rate target.
in a case like this, where you do not have a defined chipping rate, what do you do?

Each machine is going to be slightly different, so it’s best to set up your own list of feeds/speeds and with the most reasonable size chips you can get as compared to the finish you want.

I use a modified version of the procedure by PreciseBits (, and test each wood with each bit I’m going to use on it before I do a big cut. Once you figure out what your machine likes best (and what edge finish you like), just record what you did and you can use it over and over for that same bit.

Is this a carbide bit or HSS bit? Carbide is harder but more brittle than HSS, and thus will probably last longer when cutting hardwood. It’ll also stand up to heat a lot better, so once you speed up your feedrate you shouldn’t have any problems with a carbide bit. Just be careful never to drop it or impact it at all or it will chip and then it’s toast.

It was a

for fun I loaded up a 30240-02 and ran it on a piece of Lowes 2" aluminum tonight, using the default feed rate with the deWalt set on 1. When I checked to make sure, it had mysteriously gotten itself up to 2 1/2, I’m not sure how or when, and the tool was chattering the devil, so I set it back down to 1 and things settled down again. I got a fairly nice cut out of it for a first try, although it was clearing with a ball head and the grooves it left behind were not ideal… and when it was done I checked the tool and it was cool to the touch, so that made me pretty happy too.

I will definitely be trying Aluminum some more… I have heard it is possible to buy Aluminum Billets. I see only sheet on the Inventables website. Any ideas where billets can be purchased online?

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If you reduce your stepover with a ball-end mill you’ll get rid of or drastically reduce those ridges in the bottoms of your pockets. It’ll make the cut take longer but the finish will be worth it.

I have purchased aluminum bars off Amazon. Haven’t made anything yet though.

do you have a link for them?

Amazon doesn’t have a super-large variety, but I can occasionally find something heavy that they have to do 2-day shipping on since I have Prime. :smile: Here’s a good one that’s 1.5"x3"x10":

You can also buy a LOT of varieties of sizes and alloys from McMaster-Carr ( I order a lot of stuff from them at work, but have no idea what shipping costs are.

ebay is a good source

online metals has a lot of choices ( some not even metal)