Detail Carving With V-Bit - Results Too Narrow

Hi, everyone! I could use a little help with some very small engraving.

A friend of a client has been using someone in another state to carve leather stamps from handwritten messages. They would like to switch to someone local and I’ve offered my services.

Here’s a sample of one they’ve had made previously:

The stamp is 3"x2". That’s a quarter on top. The depth of cut is about 1/16". I’m 95% sure it’s made from HDPE, which is what I’ve been running my tests on.

However, I’m having trouble duplicating the results on my X-Carve. I’m using Easel Pro and performing a two-stage carve, first with a 1/16" upcut fish tail spiral bit, then with a 30 deg. V-bit.

The rough pass comes out nice and clean. (The texture you see is exaggerated by the lighting and scale.)

On the detail pass, however, the V-bit appears to be cutting away too much material, leaving the letters way too narrow. I believe the surface is a little cleaner than the following images make them look (it’s very difficult to light this material for photos), but you can see that the plateaus are too skinny:

I’m using my Z-probe before each pass and both passes are cutting to the correct depth of .06". I have my V-bit settings entered as 30 degrees with a .125" width. Different feed rates appear to make no difference.

The preview in Easel Pro looks correct, so I don’t believe it’s a problem with the file:

Are there any settings I should double check? Is there a better bit for this job? Should I continue to attempt this with Easel Pro or should I switch to something designed more specifically for V-carving?

Turning down this job is not an option, as it is a potentially budget-altering opportunity. So, I appreciate any and all help.

That v-bit has a .01" tip. So when you’re z-probing it, it’s actually .02" deeper than where it would have been if it had a perfect tip. That makes it cut wider than intended.

I’m not too familiar with Easel on what it allows with bit settings though. V-carve lets you specify tip width. You might be able to compensate by artificially setting the z-probe off by .02", but it would leave a raised floor. You might also be able to artificially increase the angle of the bit, but depending on your toolpath, that might yield even worse results.

But before you run off and get vcarve, just remember that carving this level of detail (with v-bits at least) requires everything to be near perfect on your machine. Any slight deviation in bed levelness, squareness (on all 3 axis), steps, etc will cause large deviations in your final carve. The point being is that this seemingly simple task might turn into a quest.

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Dial in your machine and get vcarve, Easel will give you nothing but grief.

This:

Also, I’d guess that’s not HDPE. It’s more likely laser engraved acetal (POM or Delrin).

Oh, I think I see what you’re saying about the tip of the V-bit. That makes so much sense.

The bit on the left is where Easel thinks it is; the bit on the right is where it actually is. And this illustration is to scale, so it looks like that would definitely result in the type of carve I’m getting.

Bit

I’ll have to try raising up the Z-probe puck with a feeler gauge. A little bit of a raised floor shouldn’t affect the the way it stamps the leather. Unless someone knows how I can set the tip size in Easel Pro?

(By the way, I did try setting the angle higher in Easel, which left some parts wider, but it gave me weird results in other areas.)

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It’s definitely possible it’s a material other than HDPE. I intend on trying some others for less fuzzy results. (That’s my second problem to tackle.)

According to the client, it is CNC carved, thought they could be wrong. Would laser engraving leave angled edges?

One of these may be helpful:

You could also go super small endmills…
https://www.toolstoday.com/solid-carbide-spiral-cnc-mini-router-bits-end-mills-with-altin-coating-for-steel-stainless-steel-composites.html?variantids=12396,0&keywords=51660

BUT you have to be absurdly careful with your feed/speed… and even just general handling. I’ve broken a lot of bits with the collet wrench

That’s funny, I actually ordered that exact EnPoint bit a couple of days ago, hoping it would solve my problem with the fuzzy edges (which aren’t really evident in the pictures above). It should arrive tomorrow.

And I’ll bookmark those mini bits, thank you.

I’ll be back in the shop tomorrow to test out these suggestions and let everyone know the results. Thanks!

These are what I use if I want small endmills: https://www.ebay.com/itm/10-0-80mm-0315-CARBIDE-2-FLUTE-ENDMILLS-SOFT-PLASTIC-DOWNCUT/150806917473?_trksid=p2485497.m4902.l9144

I think you are on the right track with the Vbit though, especially considering that it will be used as a press, the angled sides will provide more durability than straight sides.

Well, raising the puck with a .02" feeler gauge seems to have done the trick. The results aren’t perfect, but I think they’ll be good enough to press into leather. Thanks for the help!

salt rim

If you haven’t, measure your actual flat spot (mine are 0.03” which is fairly common and would cause way more havoc than a 0.01” flat) and do the math to calculate your actual Z probe difference.

Or You can buy a non-flat tipped bit.

do a test with the v-bit angle setting at 31 (or possibly 32)

My guess is that your bit is not actually 30 degrees

try it and see what happens