The answer is quite simple, just a matter of geometries. The top of the cut (or rather, the soundboard) views the cut as a circle with the router bit, while the side recieves the actual 45° angle cut. if you look at the geometry of the bit, the face is "V" shaped, while the downward view is "o" shaped.

@BeauHannamGuitars

3 жыл бұрын

Thanks Lloyd :)

The bit naturally leaves a round profile on the top because it’s spinning. But the side is getting the straight profile because you are using a chamfer bit. A round over bit would leave you with a Matching profile.

The answer is because the bit as the larger diameter of the circle on the top and the diameter is smaller at the bottom of the bit so the curve is more pronounce.

Amazing skill just laying it all out. Thanks Beau. I saw you were watching Robbie OBriens sharpening class yesterday. Robbie is a generous man.

@BeauHannamGuitars

4 жыл бұрын

thanks

The side is a different shape to the top because the router bit diameter increases from the bottom to the top. i.e. the part of the bit cutting at the top has a larger diameter than the part of the bit cutting the bottom. hence why you get 2 different end curves at the top and bottom.

Wow very good Work. Thank You.

@BeauHannamGuitars

3 жыл бұрын

thanks

thank you Beau very interesting

@BeauHannamGuitars

4 жыл бұрын

thanks :)

Been following with interest all of your photos and now videos of the arm bevel. I've done a few of the "standard" arm bevels a la Kent Everett. I like them well enough but I really want to try this style. The only thing that scares the bejeezus out of me is the thought of routing that wide purfling channel in the top. I normally use Chris Ensor's jig for my binding and purfling channels. Is my memory failing me or did I see a pic that you uploaded where you just used the attachment that came with your laminate trimmer to cut the purfling channel? I don't suppose you would consider a video of this step? In any case this is all fantastic stuff Beau - many thanks for it. I think you are the first person to demo how to do this style of bevel.

@BeauHannamGuitars

4 жыл бұрын

i may have to do a video on that part (which i haven't done yet)

The top cuts reflects the round shape of the bit while the side reflects the 45 degree angle. Will we get to see the finish with the veneer?

@BeauHannamGuitars

4 жыл бұрын

finished pics in 5 more videos

@dasuol

4 жыл бұрын

I agree. The rotation of the bit is perpendicular to the top surface plane, but parallel to the sides. If the bevel were cut with a straight bit that was tilted to a 45° angle, then the angle of rotation would be even between the top and side so you would get an even curve in both locations. I imagine that would be pretty difficult (and probably fairly dangerous) to set up though. So probably best to just clean it up by hand like you do.

@BeauHannamGuitars

4 жыл бұрын

@@dasuol you are all way smarter then me!- thanks- fixing it by hand only takes a few mins

The top of the router bit has a larger radius than the bottom part of the bit.

Do you do this free hand or use a binding jig

@BeauHannamGuitars

Жыл бұрын

To route the excess off In this case I do it free hand as the "jig" happens to be the side of the instrument- the bearing rides against the side. Jigs are good for creating the top and side purfling ledges before this happens.

@lynpugs

Жыл бұрын

@@BeauHannamGuitars Okay, that makes sense. Thank you for taking the time to answer.

Your sound is low a bit

@BeauHannamGuitars

3 жыл бұрын

Good to know

Maybe it's just a shitty router bit?

@BeauHannamGuitars

4 жыл бұрын

hahaha