Speeds and feeds question

So… question… it is possible to be running the dewalt way too fast. And what issues should I be looking for. I just set mine at 6 with feed of 45 and run it. Should I be using a lower number. Everything looks awesome except for a little bit of fuzzy hairs on some edges that sand off with light fine grit paper.

'm just wondering if I would get nicer cuts with slower speeds, I was just thinking the faster speed meant less stress on the motors as it would cut faster, no?

Yes you should be running it slower, the lowest speed setting of 1 is turning the bit at 16,200 RPM. This lowest speed is faster than most of the tools you will be using should spin. At high RPM’s you are generating lots of heat, enough heat to damage the bit and burn the wood. Not to mention the wear and tear on the Dewalt. At high speeds the brushes will wear out very quickly.

Determining the best RPM and federate is dependent on the tool you are using, the type of material you are cutting and the overall stiffness of your machine.

But as a general rule you should never need to set the RPM of the Dewalt above 2 or 3. And for most of the work normally done on the X-Carve a setting of 1 is still to fast.

I’m relatively new to CNC but this post here was incredibly helpful. Keep in mind you are balancing multiple factors here: the RPMs, which is how fast the tool is revolving, how many cutting edges on the tool (ex. 1 cutting edge vs 2 cutting edges is the difference between 16,000 revolutions and 32,000 effective revolutions and cuts), the depth of cut DOC/ depth of pass DOP = how deep the cut will be on each pass (if your machine isn’t stiff enough and the DOC is too deep the gantry will flex and cause the tool to cut at a slight angle), and your speed i.e. how fast the machine is moving the Dewalt across your work surface.

I suggest taking some time to understand how all these factors balance together when cutting or you’ll end up breaking bits, ruining material and wearing out your machines. The CNC Calculator spreadsheet is my preferred reference.

So Allen, according to this spreadsheet, If I am cutting 1/2" birch plywood with a 1/8" 2FL fishtail, I should set my Dewault 611 to just under the 1 setting and set my feed rate to 120in/min? Just making sure I am reading this right.

Hello Douglas,

What the spreadsheet is telling you is that a speed setting of 1 and 120 ipm will give you an optimum chip load. But 120 ipm on the X-Carve is not a realistic feed rate. The machine is just not rigid enough and the Dewalt is not providing enough power to cut like that.

So what you need to do is determine the depth of cut and feedrate that will provide the best cut for your machine.

The purpose of the spreadsheet is to demonstrate that the Dewalt RPM should be set to near 1 for most applications.

I would set the Dewalt to 1, set my depth of cut to .06 and my feedrate to 60ipm and see how that works on a some scrap plywood first.

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Gotcha! I just got this X-carve built and tuned in pretty well. My first cut, I did not change the dewalt speed and it was set at 6. It cut pretty well however, I have been breaking the 1/8" 2FL straight bits inside the collet. My dewalt came with the 1/4" collet and a reducer for the 1/8" bits. I have broken 3 of the 1/8" bits inside the collet. I was wondering if the speed may have been the culprit. Thanks for the quick reply!

Running the Dewalt at 6 will burn the wood and ruin the bit, once the bit gets dull from the heat it is really easy to break it.

If your setting are correct the bit should not get hot. After your carve completes and the power to the router is off you should be able to touch the bit. If it is to hot to touch then your settings are wrong.

Thank you!

I’m no pro, but when I went from my Bosch colt to variable speed makita, I was stunned at how much slower I could set the speed and get same or better results, and my bits instantly stopped turning color from being waaaay over heated, and the noise level dropped to the point I can talk over it, and the sharpness of my bits is lasting an immense time longer!!! I’m sure switching to lower speed router or using lower speeds will pay for itself in time from not having to constantly replace bits!!!