Exploding blanks?

[NotURMailman]

I have had three blanks "explode" on me while turning. The first two were bloodwood. I thought maybe it was the wood, so I started over with purpleheart. The first one there did the same thing. I have my lathe at 750 RPMs, and am using a maybe one month old carbide tipped finisher that has only been used on four pens and one cup. I am turning on a mandrel with the tailstock against the end. I must be doing something wrong. Any ideas?

 

[Silverado]

I would try turning at a much higher rpm. I turn near the top of my lathes
max. rpm. Also use a very soft touch.

 

[Ulises Victoria]

750 rpms is way too slow. I turn wood at around 4000. Sharp tools and light touch.

 

[Haynie]

Been there, done that. Fixed it with sharp tools, fast speeds.

 

[mrcook4570]

I agree with the above, crank up that speed. Aslo, inspect the tube from the exploded blank to make sure you had 100% glue coverage. It is possible for some of the glue to be wiped away while inserting the tube, which will lead to an exploding blank.

 

[NotURMailman]

Thanks guys! Sharp tool shouldn't be a problem with the fairly new carbide tip. I will speed the lathe up.

 

[eliasbboy]

I had a few happen when my drill press vice was broke. I had loose fitting brass tubes and by using CA the gaps weren't getting filled. Are the tube clean of glue after the blowout?

I fixed my vice for better drilling and switched to 5 minute epoxy. I've not had 1 problem since.

 

[NotURMailman]

I will be sure to get good glue coverage from now on too. I appreciate the tips!

 

[NotURMailman]

I am drilling on the lathe. I was going to get Barrel Bond when I first got my supplies. The salesman talked me into thick CA instead. Any specific epoxy you would recomend?

 

[eliasbboy]

I am drilling on the lathe. I was going to get Barrel Bond when I first got my supplies. The salesman talked me into thick CA instead. Any specific epoxy you would recomend?

I took a recommendation from here and use "Loctite" 5 minute epoxy. They sell it pretty much everywhere.

 

[ed4copies]

I agree with the advice to speed up your lathe.

HOWEVER!!!! Make sure you are wearing face protection!!!
If you can "blow them up" at 500 rpm, you have quite a talent---it will hurt MUCH MORE when they fly off at 4000 rpm---be prepared!!!

 

[NotURMailman]

I've been wearing the same faceshield I use when cutting metal.

So, LocTite 5 minute epoxy, speed up lathe, ensure good glue coverage.

Sounds like a winner. Thanks again!

 

[azamiryou]

How close is your tool rest to the blank? Get it as close as you can. I agree with all the other advice given above as well (glue coverage, higher speed, sharp tool, light cuts).

 

[mikespenturningz]

Also make sure you are not being too aggressive with your cut. The only times I have had blanks blow out on me is when I am forcing the cut.

 

[George417]

I would try turning at a much higher rpm. I turn near the top of my lathes
max. rpm. Also use a very soft touch.

I agree the faster speeds work better and sharp tools.
I always turn between 1200 and 2500

:biggrin::biggrin:

 

[Gilrock]

When I started making pens I was brand new to the lathe and I bought one of the Easy Wood Finishing tools with the round carbide tip because that's what the guy in the Woodcraft video was using. I felt like it was awesome and I could make the whole pen with just that one tool. But I had this one segmented blank with a horizontal piece of metal and I had it snag on the carbide edge and blow it up. So I went out and bought a brand new carbide tip...made another blank....it blew up again. I made a third copy of the blank and I got it turned by learning how to use a tool I had never used before...a Skew. I had kept hearing everyone on the forum comment about using a scary sharp skew and I owned one but it turns out when I had tried it before I was holding it completely wrong. I search youtube for videos on using a skew and landed on one of a guy turning a pen with a skew and funny enough it turned out to be Ed from Exotic Blanks. After watching that video I sharpenend my skew and tried it on that third blank and it was amazing how much better it cut. The carbide tools seemed sharper but there was something about the angle of attack that made the skew a better tool for cutting that blank. The metal in the segment was hitting the skew at an angle whereas on the carbide tool it was hitting square on. So I'm not saying it works for every situation but it's a good tool to learn to use...maybe you already are...just throwing it out there because I know I was self-teaching myself and I did a lot of things the wrong way. It wasn't till I saw another video that I realized a roughing gouge wasn't supposed to be held with the end square to the workpiece. When I first saw the video and tried it I was a little scared because it feels like it's just going to grab on the workpiece and jam back into you but instead it rides on an edge and you can learn to lean into the cutting edge. Anyways I'm rambling....hopefully this will help someone expand their horizons if they were stuck using only a carbide tool like I was.

 

[NotURMailman]

I'm completely open to trying some more conventional cutting tools. All I have right now is the three Easy Wood mini tools (rougher, finisher, detailer). What is a reasonable way to sharpen regular tools without spending a pile of money on a low speed grinder?

I followed everyone's advice; moved the belt up two pulleys, used plenty of glue (still thick CA for the first one), made sure I was making small cuts - no more explosions! Made a nice Purpleheart Slimline for my sister.

Then I tried to do another one out of Bloodwood and it exploded. So I started over using the LocTite 5 minute epoxy. That was 4 hours ago and the epoxy on the cardboard where I mixed it still hasn't hardened. I know it's a little cold out there, but epoxy should harden from a chemical reaction, and the temperature shouldn't be that big of a deal. Any ideas? I'm afraid to mess with the pen if the epoxy on the table hasn't even hardened..

 

[76winger]

I am drilling on the lathe. I was going to get Barrel Bond when I first got my supplies. The salesman talked me into thick CA instead. Any specific epoxy you would recomend?

I glue most of mine up with thick CA and have few problems. Are you spreading it around on BOTH the inside of the blank AND the tube before sliding the tubes in? A full, even coat on both halves before assembly gernally gives a great bond, and thick CA sets up slow enough, you've got time to get them in and lined up with time to spare. After it's in, I hit the ends lightly with accelerator to help it set up before the tube slides out.

 

[76winger]

When I started making pens I was brand new to the lathe and I bought one of the Easy Wood Finishing tools with the round carbide tip because that's what the guy in the Woodcraft video was using. I felt like it was awesome and I could make the whole pen with just that one tool. But I had this one segmented blank with a horizontal piece of metal and I had it snag on the carbide edge and blow it up. So I went out and bought a brand new carbide tip...made another blank....it blew up again. I made a third copy of the blank and I got it turned by learning how to use a tool I had never used before...a Skew. I had kept hearing everyone on the forum comment about using a scary sharp skew and I owned one but it turns out when I had tried it before I was holding it completely wrong. I search youtube for videos on using a skew and landed on one of a guy turning a pen with a skew and funny enough it turned out to be Ed from Exotic Blanks. After watching that video I sharpenend my skew and tried it on that third blank and it was amazing how much better it cut. The carbide tools seemed sharper but there was something about the angle of attack that made the skew a better tool for cutting that blank. The metal in the segment was hitting the skew at an angle whereas on the carbide tool it was hitting square on. So I'm not saying it works for every situation but it's a good tool to learn to use...maybe you already are...just throwing it out there because I know I was self-teaching myself and I did a lot of things the wrong way.

The angle of attack is VERY important to successful use of the skew. I always round with a gouge and then switch to the skew as soon as I can, laying initially so cutting edge is about 30 degrees to the rotating blank, then lay the side (bevel?) of the cutting edge on the rotating blank, then slowly raise the end of the tool up until the cutting edge starts slicing into the work. Then peel off those ribbons (if acrylic)! It ends up working like a hand plane on a board, but without body around the blade, just peeling off thin slices.

It wasn't till I saw another video that I realized a roughing gouge wasn't supposed to be held with the end square to the workpiece. When I first saw the video and tried it I was a little scared because it feels like it's just going to grab on the workpiece and jam back into you but instead it rides on an edge and you can learn to lean into the cutting edge. Anyways I'm rambling....hopefully this will help someone expand their horizons if they were stuck using only a carbide tool like I was.

Think of the cutting edge of the gouge, in similar fashion to the cutting edge of the skew. Ride the side, then tip it up till the sharp cutting edge starts peeling off material. In the same way as the skew, it can be positioned so the cutting edge "slices" instead of "scrapes" the material off.

Sounds like you're getting it figured out. I thought I'd toss out my technique in case it's helpful to someone.

 

[Jim Burr]

<1000 is for sanding...>3000 is for turning...pens anyway. Sharpen and hit it.

 

[nativewooder]

I would suggest that instead of butting the "cutting" edge of your carbide tool against a square blank, turn it to a 45 degree angle. That will make it less likely to take a chunk out of the blank.

 

[NotURMailman]

Thank you to everyone for all the help. After taking everyone's advice I finished the Bloodwood slimline last night. And then AFTER the fact I figured out what I believe to be one of the reasons that I kept having issues with the Bloodwood blanks...

When I cut them I somehow managed to swap the orientation of the block of Bloodwood when I layed it on my table saw (I had three blocks layed out on my work table next to the saw in the proper orientation), and managed to cross cut all of the Bloodwood blanks. I would imagine that this would make them much easier to "break out" as the issue I was having. But, they are all used up now and I will be very careful in the future to ensure I don't do that again.

With that said I ordered a bunch of blanks from one of the vendors here last night:

Black Walnut - Pear - Buckeye - Mulberry Burl - Flaming Box Elder - American Chesnut - Red Oak - Black Limba - Bocote - Black Palm - Apple - Deer Antler (woodturnersblanks.com).
It seems that a lot of his blanks are cross cut. Any special tips on turning those?

 

[Lenny]

All of the previous advice still applies. Cross cut blanks can result in a more interesting looking pen. Don't force the cut, sharp tools and reasonably high speeds. I prefer epoxy for gluing tubes in myself!

 

[NotURMailman]

I fully intend to continue following al of the advise I have recieved here. I did have two more 5"x78"x7/8" blanks left of this accidentally cross cut wood. I used another last night. I am getting them done now using the advise I got here, with one small exception.

On both blanks I got a small "tear out" down to the tube near one end as I am almost to the bushing. I was able to fix them by filling them with a thin CA and saw dust from my workbench (coming from that same blank) mixture. It did okay, but you can see it if you look real hard. I think it would show up worse on a non-crosscut piece. Then again, it may not happen on a long cut peice. I think it's just me getting more agressive as i get almost to the point of removing the bushings for final sizing...

Just wanted to throw that out there. Thanks again!