Questions about Speed & feed for hardwoods

[Eddkent]

I'm looking for info on speed & feed rates for 3 types of hardwoods.
Purple hart, Jatoba Brazilian Cherry, & Gibon Ebony.
Most of the projects I have in mind are smaller boxes with some detail work. I have the bit set that comes with the SB desktop & a few other Onsrud bits on the way that are more appropriate for hardwoods.
I'm prity new to this so any info on S & F and what bits would be appropriate
would be greatly appreciated.
Thanks
Ed

[Brady Watson]

Start @ MS,1.5,0.7 (XY,Z speed) and 12,000 RPM. Adjust speeds as necessary. You can try to cut anything at these speeds and adjust accordingly. Then make your OWN 'chart' of speeds that work for your tool - although the truth is after you cut enough stuff, you won't bother looking at it again.

If it's burning or the bit is screaming, lower RPM or increase feed rate. If it sounds labored and cut quality is poor, increase RPM or lower feed rate.

-B

[Eddkent]

Thanks Brady,
Ed

[LeoT97]

I'm a real nubie when it comes to the Shopbot but.......
I was reading through this and saw some of the woods you had posted, there are a fair number of hardwoods that burn easy. Maple and Cherry from my experience using a bench router.

Heck I'm still trying to figure how to stop busting bits

[shilala]

I use a wood mar/hardness scale to help.
Cherry is around 900. That's my base. It'll machine at 3.0ips very well, no fuzzies or chips.
But hardness isn't the end all, be all.
The more open the grain, the slower I have to go, even if the wood is harder.
Ash is around 1200-1400, with no open grain at all. I think I could machine that at 1,000mph and never have a problem.

I use shellac to stabilize open grains when I need to. Works good on soft woods, too.
In that instance, I'll do the rough work, shellac, then do the fine work.
It's especially helpful for vcarving soft woods.

All that to say "you just have to pay attention to your feed and speed and wood hardness and grain".

This is an AWESOME wood hardness chart (http://workshoppages.com/WS/Misc/Wood-Hardness-Chart.pdf). The one I use is just for the domestic, local stuff I work with all the time.

[scottp55]

Funny Leonard, I get WAY less (virtually none)burning on the 'Bot than than hand routing. Biggest culprit nowadays is the stationary belt sander.
On breaking bits, if you dial in Bradys #'s you won't go far wrong---Just to get your confidence back up, try making your pass depth 1/2 bit diameter and then gradually creep up on what's best for you. Also Ramp wherever you can.:)

[Ger21]

...............there are a fair number of hardwoods that burn easy. Maple and Cherry from my experience using a bench router.

Because most handheld routers are spinning at 25000-30000 rpm.
If your handheld router was spinning at 12000-15000rpm, you'd have a lot less burning, and your bits would stay sharp a lot longer.