Feeds & Speeds - Carbide Create vs. MaterialMondays vs. Wiki

CNC Machines Shapeoko
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Okay, I finally got my Shapeoko XXL and have tested a few projects. I’ve had good success so far, but I’m just trying to understand a little better. I read quite a few documents, used Carbide Create for a while, and watched a bunch of videos before starting.

First, I get that feeds and speeds are kind of a personal preference to an extent, but there are clearly some general guidelines and starting points as well. So, my question/confusion is the huge variance between recommendations from the Carbide 3D direct sources. Take hardwood for example using the Makita settings and a #201 ¼ end mill:

• Carbide Create Default: plunge: 12 IPM, feed: 60 IPM, RPM: 18k, DOC: .04"
• YouTube #MaterialMondays: plunge: n/a, feed: 75 IPM, RPM: 18k, DOC: .06"
• Wiki/Feed & Speed Chart: plunge: 30 IPM, feed: 65 IPM, RPM: 19k, DOC: .22"

My question is, there is a HUGE discrepancy on some of the figures between the three Shapeoko specific sources I’ve found, especially on the DOC, which is huge on some materials. Obviously I can test out the material, but I really don’t understand why the Carbide Create tool library has such a huge variance from the feed & speed chart. My question is, where should I lean more towards when starting–the videos, chart, or built-in carbide create defaults?

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The curated feeds and speeds in current versions of Carbide Create are intended to be conservative and reliable, even for a naïve user.

The YouTube feeds and speeds were worked up by @wmoy as an example for the purposes of the video.

The Wiki feeds and speeds are either a specific example from someone’s project or copied from an older set of feeds and speeds:

This is further complicated by “which hardwood”?

See:

https://www.precisebits.com/reference/relative_hardness_table.htm

and the matching calculator at:

https://www.precisebits.com/calc

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Thanks for the reply. As far as which hardwood, that’s a great question, that was probably the worst example I could have picked since that’s a super broad category. A better example would have been MDF, which is honestly why I asked the question in the first place. I did a few test signs on some MDF using the CC default settings and the quality was very good, no issues. I just felt that it was pretty slow, because of the super conservative DOC. It has a default with the #201 end mill at a .060" DOC whereas the Shapeoko chart has it listed at .3" DOC. That’s a pretty large variance (5X difference) between the default and the sheet.

So, should I lean more towards the sheet or more towards the defaults? Obviously I’ll adjust as time goes on, but I figure why reinvent the wheel–if someone else has already come up with good numbers, that’s kind of the purpose of guides, right?

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Well, the guides are for inexperienced users so I believe it makes a lot of sense to choose them on the conservative side. Furthermore, there aren’t universally good numbers for every use case.

MDF is actually very soft. As you don’t specify radial engagement, I assume you’re slotting. The limit then is more how well you can get the dust out of the slot, so it depends on whether you have good dust extraction and how deep the slot ends up. For slot depths exceeding twice the tool diameter, it can be a good idea to stick with conservative values (0.1" depth per pass).

In general, I’d recommend to experiment with the feed override: Pick a not-too-large axial engagement (say D/2), override feed to 70% at program start and then increase it gradually as long as it sounds good, or go back down when cutting a deep slot.

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I’ve got to be honest here, but speeds and feeds (for me, anyway) is a dark art.

I don’t think I’ve ever seen consistent figures for the same material being cut with the same end mill.

@cqualley quite rightly identified the differences in standards (?!) between tool selection and the Shapeoko table (although that only has settings for the #201 and #202 bits). It would be helpful, possibly, if these ‘standards’ were consistent - with the obvious caveat relating to the material being cut.

It’s easier to look up default (and consistent) settings, rather than calculate them, and get on with the project!

Oh, and I used the PrecisionBits calculator with the #201 end mill details and the feed speed calculated at 2250 inches/minute, which sounds a bit high! Perhaps it was user error…?

Aside: Wouldn’t it be great if there was a database (not unlike @gmack’s SPFP Workbook, but much simpler) where you could dial in the material to be cut, the bit you wanted to use and the settings were presented to you? Sounds like the perfect job for Microsoft Access!

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Unfortunately, no one seems to have worked out a good way to share feeds and speeds.

I put together an Airtable w/ a Google Survey Form which would allow folks to input feeds and speeds, but no one used it that I can recall — the output was like to:

https://public.tableau.com/profile/willadams#!/vizhome/Carbide3DCNCFeedsandSpeeds/Sheet1?publish=yes

The links for the Airtable and the Google Survey Form should be around somewhere on the forums here.

I really wonder if we are making this more complex than it ought to be. There are a total of 11 possible speed settings for a Carbide Compact Router and few shop environments and folks and materials would be workable for the highest few, so one could instead just chart out all of them w/ the reasonable feed rates in suitably small increments and you could note the chipload for each intersection, and list materials and the depth of cut which they are suited for.

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What? Why haven’t I seen this before?

You put a lot of work into that, @WillAdams, and I really like it!

I’m going to use this as my GoTo place for S&F, but I’m curious why you chose to do it in metric, rather than imperial? Also, are the spindle speeds calculated to be managed by a spindle controller?

Music to my ears! I’ve been thinking this has become too complicated to be an ‘enjoyable’ hobby for a while, and sometimes I find I’ve disappeared down a rabbit hole without realising it.

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The Tableau/Airtable is a direct transcription of the feeds and speeds from:

so really, doesn’t serve a purpose other than being fancy/interactive, and it gets confused by the Nomad feeds and speeds.

FWIW, I always fall back on the Precise Bits feeds and speeds testing technique when I’m in uncharted waters and it has worked well for me.

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And now I see that! D’oh!

So why was the original table limited to just the #201 and #202 bits? Carbide3D does sell quite a selection of different ones, after all.

I might take a closer look at the pdf file and see if I can incorporate other end mills, if you (or Carbide3D) don’t mind - and I can find the time!

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The original table was done by a person who has since left Carbide3D — not sure on the specifics — the pdf was made in Adobe InDesign, but not sure that it’s the best starting point (I had to fix a number of typos) — @wmoy is now creating feeds and speeds which are being placed in Carbide Create.

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Thanks, @WillAdams. I guess I won’t need to, then!

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