LumberJocks

Trouble with pull cut

  • Advertise with us

« back to Woodturning forum

Forum topic by JoshNZ posted 06-22-2015 06:19 PM 899 views 0 times favorited 16 replies Add to Favorites Watch
View JoshNZ's profile

JoshNZ

53 posts in 529 days


06-22-2015 06:19 PM

Topic tags/keywords: lathe turning shaping question

Hi everybody.

I am getting back into wood turning after a break from it, I still consider myself very much a novice.

I have been watching Lyle Jamiesons tutorials and decided I would try a fingernail grind on one of my 1/2” bowl gouges. I built a jig and was successful with a grind that looks pretty good, about 60º at the tip and the wing corners are about 1/2” back. I can turn the inside of a bowl beautifully with it, producing long curly shavings like I never have before. But, I can’t do pull cuts without catches any more :/.

If I have a bowl with the foot glued to a block on the head stock, I used to be pretty happy rolling the cutting edge into the wood at the foot and pulling it towards the rim, to refine the shape or whatever. With this new grind I can do this at the base but as I come around the the shoulder of the bowl I get a catch nearly every time. It seems I can’t find a position where the bevel is supported in front of the edge cutting. And thinking about the mechanics I don’t really know how it is possible. If your handle is down, the heel of the tool below the point of cut is always going to be unsupported. And if I use the bevel further out on the wing the tool just “rolls” and catches as well.

Is there anything obvious I’m doing wrong?
Thanks in advance,
Josh


16 replies so far

View TheDane's profile

TheDane

4997 posts in 3122 days


#1 posted 06-22-2015 08:18 PM

It sounds like you are attempting to do pull-cuts on the inside of the bowl … correct?

I know some turners do it a get away with it, but in my experience, it results in exactly what you are getting.

I have been doing finishing cuts ala David Ellsworth, and really like the results. I start with the gouge horizontal to the C/L and the flute wide open (0 degrees). Rub the bevel on the outside of the rim, turn the tool a fraction of a degree to begin the cut on the left side of the tip and push, riding the bevel all of the way to center.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#2 posted 06-22-2015 08:28 PM

No – I’m trying to pull cut the outside of the bowl, from the foot to the rim, exactly as Lyle does in the video linked in my first post.

I slowed my lathe right down and tried to get an idea of what exactly was going on, and for a while I thought I had it, I brought it back up to speed and pretty well finished the bowl, started sheer scraping then tried one more pull cut, I don’t even know why, I think for the hell of it lol.
Needless to say that bowl is now on the fire heap :(.

If you look at the youtube link in the first post you will see what I mean. I can do it sometimes and other times it catches wickedly, all while maintaining bevel contact and never letting the cut get near the wing.

Do you have a diagram or video on the inside finishing cut you’re doing? Sure could use advice there too lol
Thanks

View LeeMills's profile

LeeMills

271 posts in 761 days


#3 posted 06-22-2015 08:39 PM

It’s almost impossible to trouble shoot in a case like this.
These are two you tube videos on the Push Cut and then the Pull Cut.
You can be more aggressive with the Push Cut.
https://www.youtube.com/watch?v=1HF9IGdHCTA

As Lyle states, you take very small cuts with the Pull Cut. I would say no more than 1/8”. If you get too much wing into the cut will have a huge chance of a catch.
https://www.youtube.com/watch?v=y2xHHxTs4Yg

This is Lyle describing his grind with no “hump”.
https://www.youtube.com/watch?v=3liDhY_zxSc

Here is a video by John Lucas on correcting grinds. If you have a “hump” it is easy to correct.
https://www.youtube.com/watch?v=M9G16ylEZHQ

It sounds to me like either you have a hump or are trying to take too large a cut or both.
Also look at the angle your tool meets the wood at the start. If you are not swinging the handle then the further around the curve you go the flatter it is applied to the wood. This would be similar to the type movement as in hollowing where the handle is pulled to you in order to round the curve on the inside.

The only time I have a lot of wing in play is with a scrape where the flute is almost closed (maybe the top edge is open 1/16 at the most). If opened to 45* like other cuts a heck of a catch will occur.

On a final note I wish they would rename the cuts. Especially when you are told it doesn’t matter if you are pulling the tool to you or pushing it away it’s what the bevel/cutting edge is doing.
So why not call them a Leading Cut and Following Cut?

You posted again while I was typing this so my remarks may not apply.

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

View TheDane's profile

TheDane

4997 posts in 3122 days


#4 posted 06-22-2015 08:50 PM

I checked out Lyle’s video … he is doing what Ellsworth might call a ‘slicing cut’. It would seem that you could get a catch if you let the handle get too far ahead of the cut, which could move the cut up into the wing, causing the tool to roll to the right.

Do you have a diagram or video on the inside finishing cut you re doing?

No drawings or diagrams. I was privileged to spend a week with David Ellsworth at Arrowmont this month. He does have a DVD that illustrates the cuts he uses … if you belong to a local turning club, they may have it in their library.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#5 posted 06-22-2015 09:35 PM


It s almost impossible to trouble shoot in a case like this.
These are two you tube videos on the Push Cut and then the Pull Cut.
You can be more aggressive with the Push Cut.
https://www.youtube.com/watch?v=1HF9IGdHCTA

As Lyle states, you take very small cuts with the Pull Cut. I would say no more than 1/8”. If you get too much wing into the cut will have a huge chance of a catch.
https://www.youtube.com/watch?v=y2xHHxTs4Yg

This is Lyle describing his grind with no “hump”.
https://www.youtube.com/watch?v=3liDhY_zxSc

Here is a video by John Lucas on correcting grinds. If you have a “hump” it is easy to correct.
https://www.youtube.com/watch?v=M9G16ylEZHQ

It sounds to me like either you have a hump or are trying to take too large a cut or both.
Also look at the angle your tool meets the wood at the start. If you are not swinging the handle then the further around the curve you go the flatter it is applied to the wood. This would be similar to the type movement as in hollowing where the handle is pulled to you in order to round the curve on the inside.

The only time I have a lot of wing in play is with a scrape where the flute is almost closed (maybe the top edge is open 1/16 at the most). If opened to 45* like other cuts a heck of a catch will occur.

On a final note I wish they would rename the cuts. Especially when you are told it doesn t matter if you are pulling the tool to you or pushing it away it s what the bevel/cutting edge is doing.
So why not call them a Leading Cut and Following Cut?

You posted again while I was typing this so my remarks may not apply.

- LeeMills

I have made sure I don’t have the humps on the wings, I did a lot of reading/watching about the grind before I did it I think I have it pretty good. If anything the wings aren’t as long but there is a nice shallow arc from wing corner to tip.

I don’t think it’s the depth I’m cutting either, I barely have to roll the edge into the wood to get a catch sometimes. Little fine wispy dust can be coming off then crack…

When I get around to getting another bowl on the block I will take a photo of my situation for you guys to assess, maybe it’s simple. Until then, exactly which part of the bevel should be in contact with the wood, and which part of the tip should cut, and as you move around, should that change?

View gwilki's profile

gwilki

121 posts in 933 days


#6 posted 06-23-2015 12:11 AM

Josh: One thing you could look at is the angle of the bevel on your wings. You say that the tip is 60 degrees, and that you made your own jig. You could have a wing bevel angle that is so steep that a catch is inevitable. One of the arguments that free hand sharpeners use is that jigs result in a nose angle different from the wing angle. By free hand sharpening, they can avoid that. You can, though, change the angle of the wing angle, even with a jig.

-- Grant Wilkinson, Ottawa ON

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#7 posted 06-23-2015 01:47 AM

I do definitely have steep wings. My jig is a copy of the wolverine vari-grind thing. So the leg angle is adjustable, tool protrusion, pivot point distance from the wheel, etc. I could even swap the leg for a different one if needed. Which setting changes the wing angles? I’ve spent a lot of time trying to envisage which settings change which properties of the grind, but come up with nothing I’m certain about

Here is a photo of my grind see what you guys think.

Should the bevel ride under the cut? Or ahead of it like Lyle says? I can’t think how to get any point of the bevel on fresh wood, with an edge trailing behind it while cutting. Yet if it is under it, a bevel riding in fresh cut tracks so to speak, seems like a recipe for a catch.
Is this a fairly safe cut for everyone else? Or is it one that takes care and practice?

I turned a new handle for it today, on another note… A little longer. What size hole do you bore in the end for a half inch tool?

View TheDane's profile

TheDane

4997 posts in 3122 days


#8 posted 06-23-2015 02:52 AM

What size hole do you bore in the end for a half inch tool?

Half inch should do … point the gouge tip up, and with the blunt end of the shaft against the handle’s hole, force the shaft into the handle about ¼+” by dropping the handle and gouge down onto something solid. Invert the gouge with tip pointing down, handle up. Hold the handle and WHACK the butt of the handle with a hammer or heavy mallet several times, driving the shaft up into the handle until the gouge seats in the hole.

Here’s an Ellsworth 5/8” bowl gouge (shaped and sharpened by the man himself) ... sorry for the crummy cell phone pix:

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#9 posted 06-23-2015 03:13 AM

Would the longer wings make a difference? I think the flute on that gouge is a more of a V than a U shape like my gouge.

View Wildwood's profile

Wildwood

1881 posts in 1594 days


#10 posted 06-23-2015 12:10 PM

Before changing anything would do like Lyle did and mark tip and side of the bevel. Might have to play with mark on the side because your tool different from Lyle’s. Practice planting the bevel and making a slight twist hold that and move through the cut. Only thing Lyle didn’t show is body movement which just comes with practice with different size bowls.

Always better getting the outside perfect before turning inside because have wood support. Along with body movement supporting tool hold almost impossible to get a catch.

I have gotten catches with both pull & push cuts trying to improve outside of a bowl after finishing inside. Also have had success but still aware on shaky ground.

Little practice and will be in business!

-- Bill

View TheDane's profile

TheDane

4997 posts in 3122 days


#11 posted 06-23-2015 01:24 PM

Would the longer wings make a difference? I think the flute on that gouge is a more of a V than a U shape like my gouge.

The longer wings make for a gentler curve on the wings, so it might make a difference. The Ellsworth gouge is definitely a deep-fluted U … V-shaped gouges are not suited to the Ellsworth/Irish grinds. Don Geiger has a document on his website that illustrates cuts with an Ellsworth/Irish grind gouge: http://www.geigerssolutions.com/upload/130903%20Five%20Cuts%20with%20a%20Side%20Ground%20Bowl%20Gouge.pdf

BTW, the gouge I posted is a 5/8”, but the profile should look the same on a 1/2” gouge.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#12 posted 06-23-2015 11:03 PM

So I narrowed the tip of my gouge up a little, took some more off the shoulders and got it looking closer to the Ellsworth gouge TheDane posted. With the longer handle on it as well, I was able to true up the outside of a bowl using pull cuts. I’m not sure what I did differently, maybe I didn’t have the handle down low enough to ensure the bevel closer to the front wasn’t following. It still feels like a dangerous cut to me, but maybe that’s all the catches that have happened, will have to reprogram my brain.

I’ve noticed even though my bench grinder is humming quite smoothly the gouge still bounces on the wheel a little. Is there a way to dress/true the wheel without special diamond tools? Would a flat diamond stone or something else like that work? I’m out in the sticks for a while and don’t have any specialty wood craft shops near me.

Thanks to everyone for your help with the pull cut issue – much appreciated!

View TheDane's profile

TheDane

4997 posts in 3122 days


#13 posted 06-23-2015 11:10 PM

Is there a way to dress/true the wheel without special diamond tools? Would a flat diamond stone or something else like that work?

I wouldn’t … those wheel dressing tools aren’t that expensive and can be ordered online.

-- Gerry -- "I don't plan to ever really grow up ... I'm just going to learn how to act in public!"

View JoshNZ's profile

JoshNZ

53 posts in 529 days


#14 posted 06-24-2015 01:04 AM

Right I guess I’ll put up with it for the time being and order one.

Thanks again for all the help
Happy turning
Josh

View LeeMills's profile

LeeMills

271 posts in 761 days


#15 posted 06-24-2015 12:57 PM


Practice planting the bevel and making a slight twist hold that and move through the cut. Only thing Lyle didn’t show is body movement which just comes with practice with different size bowls.
...... Along with body movement supporting tool hold almost impossible to get a catch.
- Wildwood

I can’t agree more. One of the basic fundamentals is stance. In Richard Raffan’s early video on spindles and face work he started each session with instruction on stance. Of course it took a while for it to sink in to me because I wanted to see the tool cutting the wood not a course on “dancing with the lathe”. :)
Stuart Batty has three short (10-15min) videos covering stance (on page 2 of his listings).
https://vimeo.com/woodturning/videos/page:1/sort:alphabetical/format:thumbnail

-- We cannot solve our problems with the same thinking we used when we created them. Albert Einstein

showing 1 through 15 of 16 replies

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com