Machining Jatoba
Like other tropical hardwoods, jatoba is high in silicates and wears out knives quickly. Here is some advice on tooling and other aspects of working with jatoba. November 18, 2006
Question
I am doing a substantial stair project with 5/4 jatoba treads. Is this stuff particularly hard on tooling? We run a glue joint on the shaper with a Freud cutter. Any cautions? I'm considering looking for q-sawn for stability's sake.
Forum Responses
(Solid Wood Machining Forum)
From contributor R:
This wood is very hard. I've cut a lot of it over the last few years. Make sure you have sharp cutters, especially router or shaper bits that you use to round over the treads. I get serious tearout with this wood when routing against the grain if my cutters are on the dull side. It glues well with plain old yellow wood glue. Most of the QS has ribbon figure and is subject to tearout when planing. Drum sander or wide belt sander are about the only way to get a good finish on the QS. I much prefer to use the flat sawn. I don't think you will have stability problems with this wood either way.
From contributor U:
You can machine jatoba with a good quality high speed steel and get anywhere up to about 1000 lf of good quality milling. But where the glue joints are, the knife will not hold up that long, and my preference would be carbide. It's much more expensive, as you know. I guess you have to weigh it out. Sharpen more or longer run time?
From contributor H:
We have done several jobs with jatoba, from entire stairways to just treads and rail. Glue right after ripping. Or if you need to wait, clean the joint with alcohol, then glue. Jatoba, like any other rainforest product, is heavy with silica. It requires carbide tooling for best results. It machines much like teak. Sands good and does not take much to get a good finish on. It darkens quickly, so either cover it all or none. The only bad thing we found is that it's just plain heavy.
From David Rankin, forum technical advisor:
If you are doing over 5,000 lineal feet, I agree that carbide is the better choice. For runs under that, there are a couple of other choices. You can try WKW's Opti-knive or MSI's DGK-ACT knife. Both of these would be much less expensive than the carbide. I would expect to get at least 5,000 lineal feet with these tools, since we see some fairly good runs in maple. With Opti-knive, I have gotten 6-8,000 lineal feet in maple and with the DGK-ACT, I have gotten over 30,000 lineal feet in maple between grinds.
From contributor J:
Dave, I have to ask only because I run a high quality finish in my products. 30,000 lf? What were you running, stock for pallets or skids?
From Dave Rankin, forum technical advisor:
An example of the type of products run and the mills doing the run:
Colonial Millwork Beverly, WV - double shoe oak @ 200fpm 320,000lf with 1 regrind in DGK-ACT
Spectrum Products Greenville, SC - assortment of maple architectural profiles @ 35 fpm average 30,000 lineal feet between regrinds
Batesville Casket Panola, MS - assortment of woods for caskets, varied feed rates from 35fpm to 120fpm. Run entire day's production between regrinds.
The base tooling material for DGK-ACT is M2 steel. It simply increases the tool life due to the major reduction in heat. Heat is what dulls the tool. In rough lumber applications, such as pallets, we do not recommend DGK-ACT, since it is designed for the higher quality finish type production.
