Detailed work on High Density Fiber board

Hope maybe someone can help me. I’m cutting out a club crest on 3/4 HDF, with a depth of 1/8". Some of the crest is detailed in that the remaining pieces are about 1/8" in diameter. Some are just a bit larger. I’ve tried using a 1/16" downward cut bit, tried a 1/32 bit but that broke. I’ve tried slowing down the cut-rate to 10"/min and the Makita router is set at the fastest speed.

The problem is the small pieces get launched from the work surface and I lose this detail. I’ve tried different feed rates and router speed rates but no luck. I’m using Fusion 360 and have tried both 2d Adaptive clearing and 2D contour but no luck. Hoping someone can help with some ideas or a solution. Thanks.



Can you post a screen clip from Fusion 360 of the part that is breaking off? Some things are simply too tall and narrow to resist the cutting forces and are doomed to break. Some things you can try - use a 2d adaptive clear and set your radial stock to leave at 1mm then use a 2d contour to finish cutting out the stock that was left behind with a small step down and step over. Also you can consider using a 30 degree v-bit to create a tapered wall to it that gives it a wider base.

I don’t run the Makita router but most bits will want to run around 18000 rpm max - which I believe is around setting 3 on it. Faster than that and the balance of the parts becomes a factor in the cutting forces on your part, I’d suggest trying a lower RPM.

Hi Derek,

Thanks for the feedback. I’ll try your suggestions to see if they will fix my issue. I’ve tried the v-bit but that didn’t work either. Attached are two pictures, one from the routing where you can see how the pieces kind of got ripped out, and one from what it should look like from Fusion 360.

Let me know if you have any other ideas after seeing the pics.



I haven’t carved something out of MDF/HDF with that small and tall of a detail so I can’t offer a recipe - it will be challenging. Perhaps try offsetting those elements to make them slightly larger where it doesn’t change the overall design to the point it is noticeable.

Yep, tried that. I’ve edited the vector image to make those elements larger but I think to go large enough to not have them tear off would then change the look of the crest, and altering the crest would not go over well. The depth is only 1/8" so I’m kind of surprised it’s tearing off. One thing I haven’t tried is multipass. Maybe I’ll give that a shot making the 1/8" cut into 4 smaller cuts.

Thanks anyway.


I have been doing a fair amount of “relief” lettering in MDF for a church sign. (practicing in MDF, switching to a better product for the final)

My rule of thumb seems to be at least 0.2" across, anything less and the piece is liberated during the cut. For the depth of cut I am doing a 0.05, 0.1, 0.195, 0.2 (you were using .125) I was also using a .25" and .125" bit to do the pocketing

Realizing these limitation caused me to increase the size of my shop sign, which was practice for the church sign

For me the challenge has been a 46" sign … so I had to come up with a drill guide fixture.(the fixture works well :grinning:)

Now my letters line up well.

Notice the colon in the 11:00, those two “dots” were liberated, hope it hangs on with a better product.

I am still learning, but this is what I have learned while making lots of scrap wood…