Big catch. Ruined Stummel.

[n80]

Shaping stummel on my wood lathe this afternoon. This is just the third stummel I've shaped on a lathe. Doing a Rhodesian. Carbide tool. Square cutter. Had a catch right at the edge of the bowl that took a huge chunk off the rim. Ruined. No way to recover it and it was a really nice plateau that I had oriented for dense eye grain on the top of the stummel above the bead line. It wasn't even a bad catch in terms of yanking me or the tool around. Really disappointed. Is this something that happens from time to time? Bad place in the briar (I didn't see anything) Bad technique? (I was cutting from the front of the stummel, end on. Tool rest at the same angle as the slope above the bead line. Tool rest as close as possible. Mid height. Tool maybe slightly below mid height). Is a side approach better? Seems hard on a Rhodesian/bulldog shape.

Ways to prevent this? Live and learn? Just something that's going to happen sometimes?

I'm assuming this is less common with a metal lathe?

[wdteipen]

Catches occur when your tool gets underneath the wood.

[seamonster]

what tool were you using? I have had zero luck with gouges or other similar tools turning a pipe, like I would use turning a bowl or a box. I do all my hand held tool turning for pipes with a flat scraper. that being said, I do use a metal lathe, and can turn things cylindrical using the compound.....

Sent from my bloopty-bloop, using hooty-hoo.

[LatakiaLover]

Pussies. Yer all justa buncha pussies.

https://www.youtube.com/watch?v=5YnMcDU2JVk&t=2m46s

[n80]

I'm using a Robert Sorby carbide tool. Square cutter. Should not catch. I'm thinking I need to come in from the side and not from the front.

Question: When using the square carbide scraper tip am I supposed to fully engage the whole front edge of the tip, or just angle it in, or just the corner of it?

LL, that guy has balls of HSS.

[seamonster]

I'm using a Robert Sorby carbide tool. Square cutter. Should not catch. I'm thinking I need to come in from the side and not from the front.

Question: When using the square carbide scraper tip am I supposed to fully engage the whole front edge of the tip, or just angle it in, or just the corner of it?

LL, that guy has balls of HSS.

I use a 1 inch flat scraper, and typically just touch off with just a small section of blade, meaning the 1 inch is approaching at an angle, them slowly rotate the tool until the whole flat is cutting. you might also play with a faster rpm, and a much gentler approach. sometimes a catch is the result of a too-aggressive initial cut. you might see guys on the you - tubes hogging of quarter inch passes, but they're way past the thousand hours mark....

Sent from my bloopty-bloop, using hooty-hoo.

[Sasquatch]

I use high speed steel gouges, a parting tool, hardly ever a scraper.

Technique is everything, and in a sense, turning something as small and hard as briar is it's own challenge, watching someone turn table legs out of poplar is no help.

But all grab/kickback situations are the same, with all tools - you have to have the piece and the tool in positions where nothing can get worse if it catches, it won't pull in, it will spit out, capiche?

[n80]

I just got a stummel off the lathe this afternoon. Rhodesian again. No drama. Approached from the side rather than the front. Maybe the end grain was an issue, I don't know. Anyway, I think I'll keep cutting from the side for now unless I need to shape the rim.

[cpd2186]

Thats George in the video....

[GraniteState603]

I am having a similar problem. I am new to pipe making but am a decent turner. I can't get very far without having epic catches. I went from using the corner of a spindle roughing gouge to a spindle gouge and now I am using the micro carbide tools. different day same stuff.
Because of my woodworking prowess every time someone sees me with a pipe I am asked if I made it. I've made a couple from a kit using a belt sander mounted and my own version of a wheel. That part is easy. Now I am in this hell of catches on my lathe. I haven't tried using scrapers yet because I do more spindle work than bowls so I have less experience at using scrapers. I felt that if I can't get it done with the tools I'm good at what chance do I have with the scrapers. Please help. Thank you for allowing me to join this forum. I hope I can contribute in meaningful ways.

[Sasquatch]

My suspicion is that your tools aren't sharp enough. They have to be razor sharp, and angled appropriatley for hard wood (a slightly larger angle for the sharpening, a thicker cutter as it were). I was turning normal wood just fine, making chess sets from walnut and stuff, no issues, and briar just grabbed. I thought my tools were sharp, they weren't. They have to be scary "if I drop this on my foot it will go through my shoe, through my foot, and 5" into the concrete" sharp. And spin around 1000 rpm, should be fine. But it does take some practice.

[GraniteState603]

Thank you so much. Being so generous with your expertise is truly appreciated. Briar is a humbling experience.
The last time this happened I was using a brand new micro carbide cutter so I don't think sharpness is the issue. I've worked in difficult materials that require extreme sharpness for some time. Does speed help? i don't have a square scraper but am willing to get one. Should I get one with a negative rake angle? This issue is killing me. Stems are not a problem for me. I've been turning acrylic for some time so I've got that pretty much down. With that the trick of the trade is never drill acrylic to the end or it will shatter. Leave 1/2" and cut that off. That is why I thought I am missing some trick of the trade. I am awaiting the delivery of a metal lathe. Please don't tell me that it is going to have same issue of catches.

[LatakiaLover]

OK, here's one of the best wood turners on Earth (not an exaggeration---he makes his living giving seminars and workshops internationally, and has for decades), making a complex-shaped pipe on a wood lathe in realtime:

https://www.youtube.com/watch?v=0RU3mWYGjus

If you know what you are looking for, info-wise, there's a good chance you'll spot it in there somewhere.

[Sasquatch]

I run the triangle carbide cutters on the metal lathe, no issues.

What chuck have you got, and are you tightening it correctly? ie are you tightening at all holes where the key can go in?

[wdteipen]

Turn faster, take smaller cuts, and don't let just the tip of the square cutter make contact with the wood. With that tool, you really have to be careful that it doesn't drop below the midline of the wood.

[Maddwarf69]

I come from the bowl turning world (if your only tool is a hammer...) and do most of my stummel turning with a bowl gouge. Sharp tool, light careful cuts, and I've haven't had a catch yet. I've also used carbides for squaring off ends, and some rim shaping. I use a wood lathe, not surprisingly, and Chedda design jaws in a Nova chuck.

[CSCmachine]

My suspicion is that your tools aren't sharp enough. They have to be razor sharp, and angled appropriatley for hard wood (a slightly larger angle for the sharpening, a thicker cutter as it were). I was turning normal wood just fine, making chess sets from walnut and stuff, no issues, and briar just grabbed. I thought my tools were sharp, they weren't. They have to be scary "if I drop this on my foot it will go through my shoe, through my foot, and 5" into the concrete" sharp. And spin around 1000 rpm, should be fine. But it does take some practice.

As stated above, sharp tools grab less in oddball grain. After grinding or even with carbide, take a superfine flat diamond hone and polish that edge so it is mirror smooth and maintain your bevel. You wont have to push the edge as hard to cut. Take light cuts,and always make sure your in the right part of the center of the part being cut. Anything below center, just like negative rake on a metal lathe insert tool, will put a lot more pressure on the edge and will want to grab if the tool is not rigid enough to overcome the downward force. Handheld tools will move, not matter how hard your holding, so try to stay as close to centerline as will still cut smoothly.