CNC: Is this too ambitious?

Hi All,

Trying to make a wedding sign that sadly will not materialize before the event itself now.

After importing the design and extruding down 6 mm, I created 4 toolpaths. 2 involved the 3.175 double flute flat end mill to carve out the interior of the large J and to cut a 2D contour from the stock

Then I wanted to use a 90 degree v-bit and this is where my plans fell apart. I made the following tool in Fusion based on a half-inch 90 degree Align Carbide v-bit I picked up on Amazon:

The toolpath I generated was:

My biggest problem was that the 1/4 ER11 collet I bought would not sit properly. If I inserted it into the nut I could not insert any of my 1/4th shank bits. I know this needs to be rectified and if there are any good suggestions I’m all ears.

But once I do get a properly fitting collet, can the A350 handle the cut in the toolpath I made? I’m not worried about the engraved text, but I am worried about the large central letter. Can SM handle dropping a 90 degree vbit 6 mm into Aspen stock? I did load the file into the machine to check settings and noticed it still set the spindle speed at 12K despite my Fusion setting of 8k (btw I have no idea if that was a good setting, I was going to test and see how it worked).

I could do it in passes but I’ll have to make more toolpaths for that because when I tried passes before it skipped the engraved text in Fusion.

As a final note, my adaptive toolpath used a fake “0.5 mm flat end mill” that I really had planned to use the same vbit in to carve out the smallest corners the 3.175 flat end couldn’t reach. Followed this video in the making of it (see timestamp 22:11 on) (Beginners guide to vbit relief carving - fusion 360 90deg v bit Workbee cnc - YouTube).

Thanks everyone!

You need to have multiple passes turned on and set a step-down of .5mm (Depending on the wood you might be able to go as much as 1mm for softwoods like pine.) That way it will follow the path multiple passes and not be too aggressive. 12000 rpm is fine. There’s usually not a reason to set it slower.

Why are you entering the diameter as 1/2"? The SM can only hold 1/4" shafts (with the appropriate collet).

Not sure what your problem with the collet is. Are you saying you just got a bad one? You are supposed to insert the collet into the nut so it clicks into place and then insert the bit into the combined nut and collet.

Also, you may find that 6mm is a lot deeper than you’re imagining it is. You might want to try a path 3mm deep and see how it looks. You can always do a 2nd path if you want it deeper.


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The width of the vbit head is 1/2 inch, the shank as you mentioned was only 1/4 in (did I mix up the values?)

I’m thinking I must have had a bad collet as I can insert the shank into the collet alone, but not when the collet is sitting in the nut.

I had started with the first flat-end mill and based on that I think I agree with you that 6mm is probably too deep.

The wood I am using is Aspen but I could switch to a different stock if that is likely to give me too much trouble (first time with it as I’m still pretty green in the CNC world).

As always I appreciate your fast and helpful guidance :slightly_smiling_face:!

Aspen is very soft and sometimes when machined leaves a fuzzy surface.
Depending on how you’re finishing it might be fine but will probably need sanding.
You’ll have to decide that.
Sometimes running the path twice at the same height (or .1mm lower z origin) will remove any fuzz or strings and just smooth stuff out.
Looks like your bit info is right. Just threw me off that under the engrave tool path it was listed as 1/2". You just didn’t change the name. I didn’t notice before but 1000mm/m is probably too fast. Haven’t done aspen so not sure, but I’d start out slow and then see if you can increase it. Start at 600mm/m and you can increase the speed on the hand controller while it’s running. The SM is capable but not super powerful so i always err on slower side.


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You might have a 6 mm collet labelled as a 1/4" collet. 1/4" is 6.35 mm. A small diameter telescoping gage would allow you to measure the ID across the collet faces.

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Possibly! The one I ordered came with a 1/8th collet as well and that was also a little difficult to get bits into once seated in the nut (obviously I would use the native SM one but I thought to test once the “1/4th” gave me such issues).

I’ll probably return them and try my luck again. I found out the hard way nearly no box stores sell collets :expressionless:.