Recently, I’m working on a guitar fingerboard and in particular the dot inlays and nut slot. The dot holes are supposed to be 6mm, but they come out at 5.82mm. I just discovered that when I select “hole” in EstlCAM it correctly shows a tool path to the very limits of the object - 6mm diameter, but when I then select “pocket” to mill the center where the bit doesn’t reach (I’m using a 1/16” 0-flute mill), EstlCAM creates the pocket but retracts the limits a bit from the edges, meaning it no longer is cutting to the limits of the drawing’s object.
I can work around this by first cutting a “hole”, then following with a “pocket”, but I’d much prefer to figure out why EstlCAM retracts from the defined object limits when I select “pocket”. What am I doing wrong?
This little box in the bottom right. There’s a drop down for finish where the thickness of the finishing pass is set and next to it you select the tool. If you use this option the first pass will leave the thickness and it will be taken away with the finishing tool. I use this on most things but almost always choose the same tool to do it. When you choose a different tool it usually adds gcode for a tool change at the end of your code.
Another thing could be if the size of your bit is wrong in your configuration. You could try by making a few different sized circles and see if they are all wrong by the exact same amount. You could also use this intentionally to fix the size size of your holes in the short term by adding 1/2 the error to the radius of the bit.
Oh epiphany: 1/16" = 1.5875mm. Your error is 0.18mm total or 0.09mm on each side. 0.09mm is a lot like 0.0875. Is it possible your bit is 1.5mm? Actually that would result in a total error of 0.09mm …hmmm just thinking out loud with my fingers hopefully something is helpful haha
Bit diameter was what I first thought the problem was, and in fact it is 1.39mm, not 1.59. Unfortunately, I got exactly the same undersized result when I changed the diameter in the tools section.
I did some research after you mentioned finishing cuts. Turns out, EstlCAM is doing exactly what is intended: rough cutting just a bit undersized and expecting a finishing cut. And my “workaround” is, apparently exactly what a user is supposed to do - create two tool paths.
I’ll look into the offset and rough/finishing tool settings to see if I can eliminate the 2-tool expectation, but the truth is I will be using he same tool so making a second path is not much of a burden.
In the end, thanks for making me aware of the rough/finish cut issue. I at least understand why it was doing what EstlCAM is trying to do, and I can work with that one way or another.
Just tried adding a finishing tool with not other settings changes and it worked. I got 6.01mm dot inlay holes - close enough.
What was misleading for me, is in those tool box settings, EstlCAM shows Finishing as 0.00mm. I assumed that meant it would not offset, but when I read the scroll-over tool tip for that setting it says that if no finishing tool is selected, it automatically makes an offset of 5% of the roughing tool diameter, but does not show that offset in the Finishing box - it remains as “0.00mm”. All one has to do is select the same tool in the “Tool” drop down and it automatically follows the undersized rough cut with the correct finishing cut - no need to manually create a second tool path.
Before now, I’ve been struggling with undersized pockets and doing what you suggested - over sizing object in the drawing to correct the milling results. Now I know!
I’m using a 15 degree v-bit to lay out the lines to about 0.8mm and mill the dot holes to 6mm x ~1.6mm, and the nut slot to 3.18mm x 2mm deep, then will hand cut the fret slots with a jig and fret saw I previously built, then insert the pearl dots, glue the FB to the neck, route the fingerboard flush to the neck sides and radius the neck with a sanding block. After those steps drill the side dot holes, insert the side dots and carve the back. Then bend, cut and set the frets.
Sounds like a solid plan. I’d like to do blind fret slots. The process would be to radius the fretboard on the cnc, trace them with a V-bit, then cut them with a 0.6mm bit. The challenge is the CAM. In fusion 360 you can project a vectors onto a surface so it will trace the radius. I don’t think this is possible in Estcam or kirimoto. There are gcode senders (estlcam included) that you can probe a surface and then ‘project’ the gcode onto it but I don’t think that sounds like a great solution.
I was originally planning to 3D mill this neck, but I’ve never done 3D milling and it seemed to me that EstlCAM was not going to be the way to do it, so I downloaded kirimoto then realized there’s going to be a learning curve. I decided to make this guitar/neck by just 2D milling with EstlCAM, finish with routers and by hand, then figure out kirimoto as a side project before the next guitar.
I hadn’t thought about cutting the fret slots with 3D milling, but I see the challenge. However, while I’ve only made a few guitars, I’ve usually hand cut the fret slots flat to the depth I need at the edges than radius the board. Unless you’re trying to radius the fret slot, it seems like a solution would be a straight forward 2D milling step, followed by a radius.