Sorby Hollowing tool and catches

[Alan Tolchinsky]

Hi All, As some of you may know I just got a Sorby hollowing tool and have had a "learning curve" happening here. I have it cutting pretty well but have had two spectacular catches. I'm keeping the toolrest on center as the instructions say and my speed is 1240 r.p.m.'s. Twice I got catches so severe it broke the wood off the bottom of the piece but I was able to save it. Any help here would be appreciated. Is my speed too high or what? Thanks!

[curtis rosche]

try to cut as little as possible with it when you start going deep. in other words, dont use the whole cutting edge

[Steve Schlumpf]

Alan - speed is one of those things where you turn at what you are used to. I turn around 950 to 1000 rpm but I seem to remember that Wally turns closer to 1800 - so it is what you are used to.

Biggest thing I can think of that would cause your catches would be that you are cutting below the center line. When the cutting tip is at center or slightly above - should you have a catch - the cutting tip is just pushed into space and away from the turning. If you are cutting below center line and have a catch - it has no where else to go but into the wood below it and usually that is a severe catch with results much like you mentioned.

Even though you have the tip of the tool at center line when you first enter the hollow form - chances are you are going to angle the tip down a little as you progress deeper within the form. Usual results - major catches.

Suggest you try to hollow just above the center line and see if that doesn't make a difference.

[Wally Dickerman]

Use the tool with the handle under your forearm and tucked in to you side. Use mainly body movement to work the tool. You'll have much better control that way.

Use the tool with the cutter pointed slightly down. Work your way down the inside an inch or two at a time. Don't try to to come back and cut wood that is already thin. It'll vibrate and you'll get a catch.

I'm convinced that most big catches occur when control of the tool is lost with a small catch.

Wally

[Alan Tolchinsky]

Thanks guys for the great tips. I think I was cutting below the center line. I just did some practice on an open bowl and re read the instructions. It did feel pretty good cutting at the center line. I also think I had the cutter tip angled so that the very tip may have caught near the bottom of the form. Also I may have jammed the tool into the small opening accidentally forcing the tip into the wood. You know it happens so fast you don't know what happened. All you see is your piece breaking loose as the usual words come out of your mouth. :)

Thanks for the tips. I'll get it eventually.

[Tim Boger]

Thanks guys for the great tips. I think I was cutting below the center line. I just did some practice on an open bowl and re read the instructions. It did feel pretty good cutting at the center line. I also think I had the cutter tip angled so that the very tip may have caught near the bottom of the form. Also I may have jammed the tool into the small opening accidentally forcing the tip into the wood. You know it happens so fast you don't know what happened. All you see is your piece breaking loose as the usual words come out of your mouth. :)

Thanks for the tips. I'll get it eventually.

Hey Alan,

I had tried to get the hang of hollowing using the Sorby tools but always found it seemingly more difficult that I felt it should be .... yesterday my Lyle Jamieson hollowing system arrived and now it's very simple to hollow pieces. Highly recommended tool.

Tim

[Curt Fuller]

You didn't mention which Sorby tool you're using, but if it's the swan necked tool I'll pass on a little advice from my own experience. I've had a Sorby swan necked tool for about 4 years and for the first 3 1/2 years I was torn between giving it away and throwing it as far out into a pond as I could. Then you know the old saying "When all else fails, read the instructions". If you go to Sorby's website you can find a link to a video that demonstrates the proper use. But the key I had neglected was the proper toolrest position. The curved portion of the tool needs to be over the rest. With most turning tools you usually want to keep the rest as close to the work as possible. But with a curved, swan neck tool, it should rest on the straight part of the tool with the curve hanging over the rest. If you keep that in mind, keep the tool level or with the rest just slightly over center, it's a pretty handy tool to hollow with.

If you go to this site and scrow down to "Hollowmaster" you can watch the video. There are good demos of other tools too.
http://www.robert-sorby.co.uk/


BTW, the catches you mentioned that break the wood from the chuck are the lucky ones. I had a few that didn't break, yanked the tool out of my hands, and started propellering the tool. That'll make you go into the house for clean underwear!

[Alan Tolchinsky]

Hey Alan,

I had tried to get the hang of hollowing using the Sorby tools but always found it seemingly more difficult that I felt it should be .... yesterday my Lyle Jamieson hollowing system arrived and now it's very simple to hollow pieces. Highly recommended tool.

Tim

Yes Tim, I hear you on the " more difficult than I felt it should be" part. I'd rather have a tool that cuts than one that scrapes. But I'm a pretty patient fellow and I'm going to keep trying this. At least until I get hit with some flying wood and get a concussion. That'll be my limit I think. ;)

[Alan Tolchinsky]

You didn't mention which Sorby tool you're using, but if it's the swan necked tool I'll pass on a little advice from my own experience. I've had a Sorby swan necked tool for about 4 years and for the first 3 1/2 years I was torn between giving it away and throwing it as far out into a pond as I could. Then you know the old saying "When all else fails, read the instructions". If you go to Sorby's website you can find a link to a video that demonstrates the proper use. But the key I had neglected was the proper toolrest position. The curved portion of the tool needs to be over the rest. With most turning tools you usually want to keep the rest as close to the work as possible. But with a curved, swan neck tool, it should rest on the straight part of the tool with the curve hanging over the rest. If you keep that in mind, keep the tool level or with the rest just slightly over center, it's a pretty handy tool to hollow with.

If you go to this site and scrow down to "Hollowmaster" you can watch the video. There are good demos of other tools too.
http://www.robert-sorby.co.uk/


BTW, the catches you mentioned that break the wood from the chuck are the lucky ones. I had a few that didn't break, yanked the tool out of my hands, and started propellering the tool. That'll make you go into the house for clean underwear!


Kurt, That last part gave me a good laugh. I have been keeping the curved part of the tool past the rest. But I haven't been careful enough about the tool rest height and tip placement. Thanks for the info. I'm going to check out the link you sent. Alan

[Alan Tolchinsky]

Use the tool with the handle under your forearm and tucked in to you side. Use mainly body movement to work the tool. You'll have much better control that way.

Use the tool with the cutter pointed slightly down. Work your way down the inside an inch or two at a time. Don't try to to come back and cut wood that is already thin. It'll vibrate and you'll get a catch.

I'm convinced that most big catches occur when control of the tool is lost with a small catch.

Wally

Thanks Wally, All good tips. I'll try them. BTW I already made something with the boring tools you suggested making. Great instruction! That was easier than using the Sorby Hollowing swan neck tool.

[Alan Tolchinsky]

Alan - speed is one of those things where you turn at what you are used to. I turn around 950 to 1000 rpm but I seem to remember that Wally turns closer to 1800 - so it is what you are used to.

Biggest thing I can think of that would cause your catches would be that you are cutting below the center line. When the cutting tip is at center or slightly above - should you have a catch - the cutting tip is just pushed into space and away from the turning. If you are cutting below center line and have a catch - it has no where else to go but into the wood below it and usually that is a severe catch with results much like you mentioned.

Even though you have the tip of the tool at center line when you first enter the hollow form - chances are you are going to angle the tip down a little as you progress deeper within the form. Usual results - major catches.

Suggest you try to hollow just above the center line and see if that doesn't make a difference.


Steve, Thanks for reminding me of cutting at or below the centerline. I think this is the same for bowls too? If I only could remember the important things NOT TO DO in turning I'd be way ahead.

[Ryan Baker]

Good advise above. The most important thing (which is true for all scrapers) is to make sure you have the tool angled slightly downward (handle high, tip low). If the cutter is angled upward, a catch will jamb it in deeper and turn into a big catch. If the tip is angled down, it will just get knocked out of the way. As Steve said, you still need to have the tip near or above center so that there is clearance for the cutter -- so make sure to start with the tool rest high enough to have downward angle and still be cutting around center.

Also, be careful of large scraper cutters and using too much of the edge at once. As Richard Raffan says, they are not profile tools. You should never be using more than about 1/4" of the edge in contact at any given time or you are asking for a catch.

Practice makes perfect ...

[charlie knighton]

maybe it me, but when rough hollowing i set the speed at between 450 rpm and 550. for final cuts with the round cutter i speed the rpms up but 700 to 800 is plenty fast. i guess you get a better cut at faster speed but when i am roughing that what i am doing