Cutting Parameters in Honduran Mahogany

[catbourger]

I have been making a new chair design on my Shopbot for several month in Alder. A new customer wants the chair in Honduran Mahogany. It is much denser than Alder. My composite nailer does not work very well in the 1.25 inch thick material.

In alder, I cut at 6 ips, 14,000 rpm and take off a quarter inch in each pass. I'm cutting profiles with a 3/8 endmill and mortise slots with a 1/4 inch endmill.

Do I need to change these parameters for Mahogany?

[Ajcoholic]

Real Honduran is fairly light (at least compared to many alternative today like African mahogany). I'd say try it as is but is also try reducing the rpm a wee bit just to see. I run a lot at 11 to 12k

I cut a lot if hardwoods regularly ( hard maple, walnut, cherry, alder , ash and oak) and don't really worry too much if at all regarding the species.

[catbourger]

Thanks Andrew. How do you hold down random size pieces of hardwood?

[Ajcoholic]

Thanks Andrew. How do you hold down random size pieces of hardwood?

Generally I use two or more aluminum clamps ( I use the incra brand) in a T track in the table. I also make fixtures to hold down parts if I'm doing repetitive parts. Some times wood screws but mainly the aluminum clamps. If you make a fixture to take the sideways loads (ands screws that to the table top) a couple clamps will easily hold down even a large part especially if you use spiral down cutters as I mostly do.

[catbourger]

Thanks Andrew. I have a t-track system as well. My problem is the randomness of the width of parts. I just have to be more careful in selecting my lumber and rip it to the same width for a series of the same parts.

[catbourger]

It just sunk in to me!! Your Incra clamps don't require that the hardwood piece be a precise dimension. My Shop Fox clamps, which clamp by horizontal pressure only do require precise width, to say an eighth of an inch or so. Thanks for mentioning the Incra, Andrew!!

[jbuell]

I mostly cut and carve hardwoods and depending on your tool path movement or strategy you may need to change your move speed or rpms. I use to the Janka hardness scale for a point of reference. If it is a significant jump from hard to soft or vice versa I slightly adjust either variable for optimum surface quality and minimum sanding.

http://en.wikipedia.org/wiki/Janka_hardness_test

[catbourger]

I've only cut three different species on my CNC in the four months I've been using it. White Ash (1320), Honduran Mahogany (800), and Alder (590). There seems to be a large variation in the Janka Hardness of the three, but I've used the same speed, bit types and sizes, feed rate, and pass depth on all three successfully. So I am wondering if the Janka hardness is really relevant to CNC cutting parameters?

Of course it would be relevant to fastening or hold down type. My Raptor composite nailer works better in Alder than it does in Mahogany.