A bad day with Ambrosia Maple

[petebucy4638]

I started off the morning with a 4x4x8" long Ambrosia maple blank mounted on centers. After cutting the shape of the vessel, I discovered a very thin crack that ran almost the entire length of the timber from side to side. This was not a repairable, shallow crack. Nor was there any possibility of carefully cutting the crack out of the work. It went in the firewood pile.

My second Ambrosia maple blank was 4x4x12". Mounted on centers again, I started turning the blank into a cylinder. I started with a spindle roughing gouge. After a while, I decided to switch over to a 1 1/4" skew, hoping that peeling cuts would be a faster way to go. I was wrong. This blank had a concealed defect - most likely a result of the outcome of damage done by the Ambrosia beetles. While the spindle roughing gouge takes a very narrow bite of the timber, a peeling cut with a skew presents considerably more tool to the wood. This blew out the defective wood, which spit the entire length of the black, except for a couple inches near the headstock.

The 10" torn-out shard of wood continued to spin for a couple of revolutions, at least, in spite of hitting the tool rest as it went around. My left arm is slightly worse for the wear. I have a couple of bruises, one looking like a knife slash and one about the size of a quarter. There are two lesions that were easily covered with band-aids. There is some reddening, without any bruising, over most of my forearm. My open-fingered gloved left hand was uninjured. I had on a Lexan face shield - I don't think that anything hit the face shield.

After cleaning and dressing the cuts on my arm. I went back to the lathe and carefully removed what was left of the defect with a very sharp spindle roughing gouge, standing well out of the line of fire.

I have turned a lot of Ambrosia maple, both spindle work and face work. While all of it has defects from the Ambrosia beetle, these are the first blanks that had serious defects, and certainly the first blank to come apart. In the final analysis, I think that I'm going to rely more on my spindle roughing gouges going forward, instead of a more aggressive skew doing peeling cuts.

One of my non-woodturner friends asked me months ago why woodturners don't wear more protective gear, especially arm and chest protection. While I have seen turners use chest protection designed for Motocross riding, I had never seen much of anything that would be safe to use for arm protection. He suggested elastic Kevlar arm sleeves. Kevlar sleeves might not do a lot to protect from bruising, but they should help with abrasions and cuts.

 

[Jim Wallace]

Reduce your speed

 

[iclark]

On the 4x4x8, with a crack all the way across and almost the full length, you might be able to persuade the wood to complete the split into 2 pieces. You could then glue it back together with epoxy. For extra effect, you could mix some crushed rock (turquoise can be nice) or dry coffee grind into the epoxy.

 

[petebucy4638]

On the 4x4x8, with a crack all the way across and almost the full length, you might be able to persuade the wood to complete the split into 2 pieces. You could then glue it back together with epoxy. For extra effect, you could mix some crushed rock (turquoise can be nice) or dry coffee grind into the epoxy.

I tried to make a clean split to either salvage the two sides and use them for a couple of small bowls, or to possibly glue them back together. What looked like a clean split, wasn't. It was not possible to glue it back together without a lot of torn fibers. Neither of the two split pieces would have made much of a small bowl, either.

 

[smallboat]

glad you are alright

 

[petebucy4638]

Reduce your speed

Most of the time, I will run thicker rectangular blanks though the table saw to take off the corners. In this case, I wanted to experiment with a square base under a turned vessel, so I didn't run the blank though the table saw. The lathe was running at 1000 rpm, and I was cutting slowly with a spindle roughing gouge when I first started tuning the blank. I still think that when I switched to doing peeling cuts with a skew, that the more aggressive skew is the reason that the defect tore out the way it did.

It is not unusual for me to turn a split down to good wood when doing spindle work. I generally use a spindle roughing gouge, and have never had a problem in the past. Sometimes I use a skew on sound timber, like ash, to quickly turn the blank into a cylinder. Again, I have never had a problem doing this before.

When working with spalted or other unsound timbers, it is probably a good idea to avoid peeling cuts with a skew. No amount of visual inspection can tell you what defects are hidden inside the timber. The first indication that I ever had that spalted timber, Ambrosia maple, etc. have more structural issues than I had expected was when I put a spalted lidded box on a vacuum chuck, and it leaked air like a sieve.

When turning through a crack, I frequently use a narrow parting tool to make shallow cuts that segment the wood around the crack into shorter segments. That way if something breaks loose during turning, all that comes loose is a small piece, and not a 12" chunk. I didn't do this yesterday because the defect was not visible.

The more that I use a spindle roughing gouge, the more that I realize how versatile it is. With some practice, I was able to make some nice flowing shapes with a finish that can rival any gouge. I suppose that one of its safety features is that it does not cut deep, like my gouge did.

Live and learn.

 

[petebucy4638]

glad you are alright

Thank you. Me too! I generally don't expect issues like that from spindle work. Bowls are where I anticipate problems like this.

 

[HITCH-]

Post a picture of the first piece and there may be some good suggestions of what you could make out of the remaining wood.

 

[petebucy4638]

Post a picture of the first piece and there may be some good suggestions of what you could make out of the remaining wood.

The blank had already had the outside shaped to become a hollow vessel. After the split, there wasn't much to work with, unless I wanted to make one of those tiny bowls that Richard Raffan turns out of his scrap material.