Help understanding feeds and speeds for newbies

I’ve had the X-Carve for a couple months now, and my experience has been somewhat disappointing so far.

I got the machine in the beginning of July, and have only had one or two successful carves. The Inventables support has been wonderful, and these forums are incredibly helpful, but I’m still not having much success. I want this to work out-- I have a huge list of projects I want to try!!

When I got my machine, my spindle mount was out of spec, preventing one of the eccentric nuts from seating properly in the extrusion. I filed it down to the best of my ability, but it still wasn’t quite right. This caused a lot of machine chatter, and resulted in a scary situation where the entire z-axis fell off, and the spindle drilled through my work piece, and nearly started a fire (I had run to the bathroom for a minute).

Customer support sent me a new mount and spindle, and very kind, apologetic, and wonderful to work with, but after a month of troubleshooting after getting the replacement parts, I’m still having issues, which I attribute to feeds and speeds.

It seems as though I am doing something very wrong. Even when I am running at INCREDIBLY shallow depths (.007 at 50in/min), I get chatter. Plus, running a job at that shallow a depth means that it takes FOREVER to carve out anything. (Fill settings removing 1/4 inches of material out of a 3x3 inch area took over 3 hours). When I boost up the depth per pass and lower the feed rate, the chatter gets worse, and the job fails.

My 1/8 inch and 1/4 bits are much worse than my smaller bits, but it seems that regardless of what I’ve tried, the eccentric nuts are working themselves loose, and the spindle is chattering during the cut. Occasionally, it even seems like the g-Code for the pass is getting off slightly (the machine will start cutting a line that is off by a centimeter or two. (The deeper the pass, the more worrisome that is, as you might imagine).

Does anyone have any suggestions about calculating feeds and speeds? I don’t have information regarding chipload for my bits, so I’m just doing a LOT of trial and error. But this has been expensive, and my wife is getting annoyed how much time I’m spending with nothing yet to show for it (other than some new knowledge).

I have documented the entire build and prep work processes via video with the intention to teach newbies how to understand and use the machine on YouTube, but until I get the kinks worked out, I don’t feel comfortable putting these out there.

I am committed to figuring this out and making this work, so any suggestions would be incredibly appreciated!! Thank you guys so much!


a few possibilities:

  1. RPM is to slow with the feeds your using (try 12000RPM at 50IPM in wood) that should give you great results

  2. Bad Bits (Bent, Dull, etc.)

  3. TIGHTEN THOSE NUTS BOY!!! They should not rattle loose

  4. something is loose… oh wait that was the last one… MAKE SURE EVERYTHING IS TIGHT!

  5. Sorry about CAPS LOCK but it just sounds like things are to loose (Belts, Nuts, Bolts, Wires) could be anything my friend)

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@NickCook-- Thanks for responding!

My RPM is currently set at 12000RPM (on automatic spindle control), the bits are new, and the nuts and belts are TIGHT! The belts have a pitch to them when you flick them, although I’m not sure how tight they are compared to everyone else. All of my axes move beautifully when jogging the machine-- very smooth and consistent across the entire axis, which makes me think that the power to the motors is solid, and the belts are adequately tight. But is there a better way to test this?

For the nuts coming loose, it seems that they stay tight until the chatter starts. Once things start vibrating, the eccentric nuts tend to work themselves loose. Maybe I could put some loctite on them, but I do want to address the underlying issue with the chatter so that I don’t burn out my spindle or screw up my work.

I did have a few wires come loose on one of the Y-Axis motors after my catastrophic failure, but I’ve fixed that as well. I’m wondering if my Arduino to gShield connections are soldered wrong or something…

Another thing to check is to make sure the collet is sitting properly, if there is a chip of something causing it to be just a hair off, that will cause vibration/chatter as the bit is just a hair off center/slanted.

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I know you just got your new spindle mount, but if really want to use your X-Carve seriously you need to abandon the stock spindle and upgrade to a router. The Dewalt 611 is a good choice since there is a mount for it at Inventables.

With a router and a tight tuned machine you will be able to cut at feed rates of 50 to 140 inches per min at depths of half the cutter width.

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I’ve definitely got the Dewalt on my list, but there’s no way I can justify that purchase until I figure out the basics of how to complete some basic projects. My latest project got about 75% of the way through before it failed, and since I don’t know of any way to tell Easel to start at home but to start cutting at a certain depth, I’m going to have to finish it with a jigsaw and sander. It’s not ideal, but it’s better than throwing an expensive piece of Baltic Birch plywood in the garbage.

I want to get the machine tuned up and doing SOMETHING before I spend more money on the upgrade to make it work BETTER.

With all the power off and the spindle in the middle of your work area, if you grab the end of the bit and try to move it left/right or front/back is there any play at all? Does the spindle carriage assembly have any wiggle at all when you try to move it? Even a small amount of play can make the machine perform very badly.

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Sorry if I missed it, but what materials are you cutting?

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Hi everyone. I am an uber newbie- just set her up an hour ago. I am having what I think to be similar issues with my new x-carve. I used an 1/8 bit on soft pine and the chatter was so bad it loosened the factory motor mount screws, as well as an eccentric nut. My spindle mount/spindle worm drive disallows me from properly adjusting the lower eccentric nuts. Lastly, when I adjust the eccentric screws, the machining is rough enough that it cuts the mounting bracket, leaving shavings; adjusting from the bolt head would obviously be better, but the angles do not allow such adjustment. I am now using 1/16 bits and the chatter is greatly improved, but this shouldnt be necessary, especially not in pine.

Am I doing something wrong here?

Jeremy, it sounds like you have a lot going on. (and most of it sounds bad)

I am not sure what you mean when you say you cannot adjust the lower eccentric nuts. Did you modify your assembly somehow? If you put it together correctly you should be able to put the short end of an Allen wrench on the inside bolt head and a wrench on the nut to adjust.

I am also confused by you saying that it is cutting the mounting bracket? What is cutting it? Sounds like something is horribly wrong.

You should be able to use a 1/8 bit with no issues.

Thanks for the response. The mounting bracket/motor mount is about 1/4" shy of the necessary clearance I would need to get the allen wrench between the nut and the face of the bracket. When I say cutting, I mean that the face of the bolt that touches the face of the bracket scrapes the face and leaves shavings. It would have been awesome of the eccentric nuts shoulder was tall enough that it could fit a thin washer between it and the surface it mounts to.

Can you take some pictures and post them, it sounds like something is not put together correctly.

Like someone else said… upgrading from the stock " vibrator" to a cutting tool is a most. I got my x-carve 3 weeks ago… started on this…

that is mdf, took about an hour for the three pieces… rocked and rattled the whole time… lost one set due to the nuts shooting of.
then I got the dewalt 611 and mount…

I have the 611 with a 1/4 downspiral bit running 100ipm .125doc and other then still needing to adjust the pot for the x-axis it cuts like the wood isn’t there. dust collection is a must… because this thing makes chips… lots of wonderful chips.


I will check these things out and let you know! I can also post a video of the problems in action if that would help! Thanks for your help!

So far, I’ve cut MDF, acrylic, solid birch, Baltic Birch plywood, and HDPE. I just got my hands on some Ipe as well, but I am not sure how that will cut since its diamond hard.

The acrylic cut the best (I was using a 1/32 bit at a pretty slow feed rate and DOC), but I broke the pieces because I couldn’t get the tabs to let go. That was my fault for not using a coping saw and my files to get them out though. I’m very excited to try out the new tab customization feature as well!

Hey Jeremy. It sounds like your spindle mount is slightly out of spec. Mine was as well, and Inventables was able to help me out. I would suggest taking a small file or some sandpaper to the hole to remove a tiny bit of material before trying to get a new extrusion, but it depends on how off it is. My lower right eccentric but wouldn’t seat at all, even after some filing.

As for tightening with the Allen wrench, I know what you mean. I’ve been able to access the hole, but only by taking my wrench to the nut at the top of the z-axis and lowering the spindle to the surface of the material (I take out my bit for this). Once you get low enough, you can get access to the bottom bolt from underneath the x-carriage. Repeat that process if you need to tighten up the top eccentric nut, but that one shouldn’t be as hard to get to.

That looks so awesome, @JohnSheak. Did you have to stiffen up the x-axis at all to help bear the additional weight of the 611? How loud is it? My whole set up is in a 60 sq foot storage closet that could substitute for a loudspeaker. The stock spindle is pretty quiet (when it’s not chattering and freaking me out), but when I turn on the shop vac, it is painfully loud.

The noise wouldn’t keep me from upgrading, but it would make me build an enclosure!!

That is the sound you will hear, chattering, cutting sound. Dewalt is not louder then stock spindle. Only rising sound if you turn speed dial all the way up, wich is not recommended, you don’t want to cut anything with 27000 rpm. Usualy stays between 3 to 4, plastic cutting stays 1.

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It doesn’t sound that much louder then the stock spindle does when it is struggling though… well anything. I still use hearing protection, but I use safety glasses and hearing protection whenever I use any tools, table saw and such.
I really cant judge how loud it is because I cant really hear it over my vacuum cleaner and pancake compresser ( need to make a baffle box for that sucker…) One thing you will have to make sure is that you have dust collection and I stated in my other post; because this thing can hog out a lot of material very fast… but can also kick it up in the air just as fast. I wear a resperator as well, just something I am used to from woodworking… My next task is to build an enclosure around it, to keep that dust in one place.
for the enclosure as well as the vac and separator I already have I plan on using something like this…

I will add, for a storage area, you might consider building something like above, to enclose the x-carve and the vac. But you could aslso pick up some of that foam insulation panels they have at lowes… to dampen some of the noise.