Question about cutting two materials

[johnm]

Folks -

Okay, have any of you ever heard of Kirei? It is a new panel good, wickedly expensive, Well over $200+ for a 3x6 panel. In an 80mm panel, it consists of 3 plies. The board is made of ag waste - sorghum stalks. We are doing simple cut throughs. But the distributor really couldn't tell me very much about how to rout it - their general guidelines are 2 flues, 20k rpm, but that's it.

Second question - have any of you done any V bit carving in Jarra (Red Eucalyptus)? We have a prospect that wants a sign cut using Jarra, and I've never worked it before.

Thanks for any assistance...

John

[Brady Watson]

John,
That panel is over 3" thick and it will be a real bear to cut. If you are running an Alpha, you can get away with a 6" OAL, 4" CL 1/2" end mill. You'll need to set your Safe Z to no more than .5" and make sure it is set that low for Zzeroing....otherwise you'll top out the Z axis and get a motor/driver fault (and possibly lose position) You'll want to cut it in .25" passes to keep the tool from breaking or 'trailing' causing an off-spec part. Other than that, you should be good. For the heck of it, I would use a downcut to break thru the 1st layer of skin on the material (an 1/8" is good enough) then follow up with the end mill (upcut). This will give you little to no tear out on the faces of the panel.

For v-carving...Just try cutting it conservatively with small stepovers and stepdown values. This will go far in giving you a good cut in unchartered territory. You don't really want to go any faster than 2 IPS when v-caring anything...I like to run about 1.2,.7 depending on the size of the letters...The smaller the letter, the slower the cut. I would try 15,000 RPM as the baseline and adjust while it is cutting, watching for bogging or burning.

-B

[johnm]

Brady/All

I'm sorry - I've just tested positive for AARP.. The panel is 20mm not 80....

I do like your idea about a scoring cut, I hadn't thought of that....

Cheers,

John

[Brady Watson]

"I've just tested positive for AARP.."

Now THAT's funny!!!


-B

[fleinbach]

John,

Is that contagious I think I got it too.

[davidp]

John

Is that Jarrah, (Eucalyptus marginata) you are asking about. It is a native of Western Autralian and it is hard and dense. It dresses to a very deep rich red but will age eventually if unfinished and exposed to the elements to a slivery grey. It resists mould and is an ideal timber for out door furniture and decks. Because it is so dense you can use much smaller sections to make your furniture and it will retain its structural integrity.

Check out www.woodfinder.com/woods/jarrah2.php (http://www.woodfinder.com/woods/jarrah2.php)
for a brief description, www.boral.com.au/timberflooring (http://www.boral.com.au/timberflooring) for another decription.

Jarrah machines beautifully but your tooling must be sharp, I cannot stress this enough. You also need to cut it as fast as you can or it will burn and you will spend forever trying to sand out the burn marks.

Like all Australian hardwoods you must cut it quickly and not dwell as it will burn very badly. We cut jarrah at around 13000 rpm at approx 75 to 90 mm per second which is 3 inches to 4 inches per second but if your tools are not sharp forget it. If you need to, cut it in two or more passes but whatever you do do not slow down.

The best part is that if your tools are sharp and you cut it at the right speeds and feeds you won't have to sand it at all, it will produce a near perfect finish straigh from the cutter and it really loves an oil finish.

I hope this helps.