WoodCut BowlSaver Woes

[Tim Pettigrew]

I have a WoodCut Bowlsaver (the original 2 bladed version) which I use fairly frequently.  I have had a recurring occasional problem with this and wondered if anyone else has had similar?

This last occurred yesterday when I was using the smaller blade to cut a core from a Cherry Laurel (Prunus laurocerasus) bowl (170mm diameter, 60mm depth).  The blank was held securely with an accurate dovetail to fit my 100mm jaws with a SuperNova2 chuck.  I had sharpened the blade as recommended and turning at a speed of 600rpm on my Nova DVR lathe.  I was advancing the blade extremely gently stopping frequently and withdrawing it to clear shavings.  Approaching the end of the cut, without any warning  there was an almighty catch which completely stalled the lathe.  The wood was still held securely in the chuck with no apparent movement of the tenon.  I withdrew the blade checked all was secure and tried again.  Cutting proceeded for about another 10mm when the same thing happened, another catch which stopped the lathe in it's tracks.  I withdrew the blade and was eventually able to break out the core.  I checked that there were no metal or other inclusions in the blank and the wood where the catch happened showed no abnormalities.

I am at a complete loss as to what might be causing this and would welcome any advice as to how the problem can be solved.

Tim

[GBF]

Sounds like the blade might be at the wrong height

[Twisted Trees]

I think the cutter height is well worth checking. I also run mine a little faster than you around 750rpm mark, find it runs smoother at this speed. (I am in the habit of rough turning the outside of each bowl first so balance is not an issue) Another thought is heat, is the cutting bit or support arm getting hot, this could expand it just enough to cause a problem.

[Tim Pettigrew]

Sounds like the blade might be at the wrong height

Thanks for that George. I hadn't checked the blade height as I assumed that it would be still on centre height as per the last time I used it.  Have now checked (the depth collar was unchanged), and the cutter is dead on centre height so is not the obvious cause of the problem 

[Tim Pettigrew]

I think the cutter height is well worth checking. I also run mine a little faster than you around 750rpm mark, find it runs smoother at this speed. (I am in the habit of rough turning the outside of each bowl first so balance is not an issue) Another thought is heat, is the cutting bit or support arm getting hot, this could expand it just enough to cause a problem.

Many thanks Pete. Have ruled out cutter height which is spot on centre and the outside was rough turned so balance also not an issue. I don't think that heat is an issue as I frequently withdraw the blade to clear accumulated shavings (with a paint brush) as that can cause a jam. So I am wondering if your suggestion of increasing the speed is the answer🤔?

[seventhdevil]

i've the same device and have had this on occasion but it is in my opinion down to feed speed and grain direction as you get to the center of the bowl.

don't forget you are no longer cutting the same grain as you were on the quartersawn surface. you have a mixture of face and endgrain as you get to popping the saved bowl out and i've always just taken them on the chin and started again til it eventually gets there.

from memory the cherry laurel i turned did a similar thing so you are not alone wit that species given you problems with it.

you can hear at the end of this video (just before the bowl pops out) the sound it makes when the grain direction changes.

https://www.youtube.com/watch?v=I2Ocfi0OAos&t=14s

[Tim Pettigrew]

i've the same device and have had this on occasion but it is in my opinion down to feed speed and grain direction as you get to the center of the bowl.

don't forget you are no longer cutting the same grain as you were on the quartersawn surface. you have a mixture of face and endgrain as you get to popping the saved bowl out and i've always just taken them on the chin and started again til it eventually gets there.

from memory the cherry laurel i turned did a similar thing so you are not alone wit that species given you problems with it.

you can hear at the end of this video (just before the bowl pops out) the sound it makes when the grain direction changes.

https://www.youtube.com/watch?v=I2Ocfi0OAos&t=14s

Thanks for that Steve.  Reassuring to know that I'm not the only one experiencing this.  Will do as you suggest and take it on the chin just so long as it doesn't damage the lathe.

Tim

[gmansfield]

I don’t have that make but have the McNaughton bowl saver. I have Lao experienced the same issues with that and what I have found is firstly make sure you sharpen your tool before starting the cut using a diamond hone. The next thing is to constantly “push - pull” the tool. By that I mean push it in cut a bit then withdraw it a bit. This gives the swarth a chance to clear (the reason that it binds). This is vital with wet wood which tends to bind even more. It is a bit of a knack but once you get it, it soon becomes second nature. Also I found that 800rpm is best for my system as when it was at 500rpm it seemed to bind more. Hope that helps Graham

[Tim Pettigrew]

I don’t have that make but have the McNaughton bowl saver. I have Lao experienced the same issues with that and what I have found is firstly make sure you sharpen your tool before starting the cut using a diamond hone. The next thing is to constantly “push - pull” the tool. By that I mean push it in cut a bit then withdraw it a bit. This gives the swarth a chance to clear (the reason that it binds). This is vital with wet wood which tends to bind even more. It is a bit of a knack but once you get it, it soon becomes second nature. Also I found that 800rpm is best for my system as when it was at 500rpm it seemed to bind more. Hope that helps

Many thanks Simon, most useful especially the speed.  Up to now I have used 600rpm so will try running at 800rpm as you suggest.  I always do the push pull to clear the swarf and also sharpen with a diamond hone before each use.

[gmansfield]

I don’t have that make but have the McNaughton bowl saver. I have Lao experienced the same issues with that and what I have found is firstly make sure you sharpen your tool before starting the cut using a diamond hone. The next thing is to constantly “push - pull” the tool. By that I mean push it in cut a bit then withdraw it a bit. This gives the swarth a chance to clear (the reason that it binds). This is vital with wet wood which tends to bind even more. It is a bit of a knack but once you get it, it soon becomes second nature. Also I found that 800rpm is best for my system as when it was at 500rpm it seemed to bind more. Hope that helps

Many thanks Simon, most useful especially the speed.  Up to now I have used 600rpm so will try running at 800rpm as you suggest.  I always do the push pull to clear the swarf and also sharpen with a diamond hone before each use.

Hope it helps Tim

Graham

[Wood spinner]

Not sure if my view on this is any good but it works for me

Even when bowl turning I always have the tool cutting edge slightly above center line , That way if you do get a catch ( I don't  ) the tool has some space to fall / drop into , If you are on the center line and get a catch the area below the tool is smaller and BANG one big catch

That's my 2 p worth 

[Tim Pettigrew]

I thought that it might be useful to update this post after following the advice so kindly given as to the constant catches I was experiencing in operating the Bowlsaver.  The main advice given was to increase lathe speed.  I had always operated at a speed of 600rpm and the advice given was to increase this (See the following quotes).

This at one stroke has solved the problem and I have just completed some coring of semi-seasoned Oak using the Bowlsaver at a speed of 750 RPM and have had no further binding or catches at all.  Demonstrates the value of the forum when sharing problems.  Thanks to everyone for their contributions.

Also I found that 800rpm is best for my system as when it was at 500rpm it seemed to bind more. Hope that helps

 I also run mine a little faster than you around 750rpm mark, find it runs smoother at this speed.

[seventhdevil]

doesn't surprise me that the speed was a little low. not sure why i never said i run mine at a higher speed on my last post.

for the smaller knife i can go up to 1000rpm if its green. slower if the larger knife is in there as for me it will be the speed at the tip over anything else.

glad you got it sorted.