I just wanted to share something I had learned in my attempts to cut 1/4" purpleheart hardwood. It is notorious for giving EVERYBODY issues, but I believe I have figured out the trick. It will still require a little cleanup to remove excess char, but the edges are clean-cut with only a little force needed to push it out of the surrounding board. I’m not an eloquent writer, nor does this really need a massive write-up, but I’ll give some explanation as to how I got to these settings.
I discovered that purpleheart cuts better HOT than cold. I first tested just a line, with the settings above. It cut remarkably well and was cleaner going AGAINST the grain as opposed to WITH. Then I tried a circle using the settings above. Purpleheart gets hot when cut; it holds energy well, which I believe is why it chars so much. I went ahead and tested what would happen if I cut a circle with one pass, let the wood cool, then repeated it twice more. It did NOT want to cut, and started smoldering. It came nowhere close to cutting through!
This all started because I was trying to cut out an image that had 5 different sections to be cut. What I discovered was that instead of letting it cut all the shapes once, then repeating, I needed to cut each shape individually with the 3 passes at once. So I changed all the cut lines into different colors so that they would cut individually.
Hot Purpleheart for the win! I hope this helps somebody out C:
Have you tried this again to see if it was a fluke?
My experience with purpleheart boils down to: it’s a jerk and will fight you, and the settings I used on one board don’t necessarily work on that same thickness board later. It is highly variable and dense, like Bubinga or Sapele, it just isn’t easy to deal with.
I’ve only used the one board of 1/4"
But I’ve found that on my 1/8" boards, using the same settings for that thickness works for every board I’ve gotten that is 1/8". So I’m 98% confident in these settings for future 1/4" boards.
Well, I know that each piece of natural wood is unique. That is a benefit and a problem. Yet it makes each project unique.
The approach @crkjelstrom proposes appeals to my “why does this happen?” way I like to analyze things. This is definitely a technique to remember and try in future. I have not tackled Purple Heart yet, but when I do it will be good to have this in my toolbox. Thanks for the eloquent write up!
The more materials we try, the better equipped we are to succeed. All materials have pros and cons, and I love using each to leverage their desirable properties to the maximum.
Sharing your results is great even if the exact settings don’t work for everyone, it gives us a starting point.
I made some wood puzzles from multiple species including purpleheart, and it was the worst to figure out, and even then some pieces cut from the same strip were not as good as my samples. It was only 2.5mm (~1/10"), like a paint-stirrer…
One of the prettiest woods, and so temperamental. Thanks for sharing what worked for you.
I have purpleheart I have not tried to cut yet. Thsanks for the heads up!
Excellent! Appreciate your settings!
Thanks for sharing your process and results. I’ve only worked with 1/8" Purpleheart and had minimal issues with it, but I’ve been braced for the eventual battle that everyone speaks of.
Are you changing the focus height when you cut a 1/8 inch board? Or are you using the exact same settings as above (passes, focus height and all) to cut a 1/8 inch AND a 1/4 inch?
No, I change to .125 for the 1/8" boards. And only 1 pass. And probably more like 135 speed. But I don’t remember, it’s been a long time since I’ve cut Purpleheart now.