Woodcut Pro-Form bouncing

[olaf Vogel]

I spent a few hours hollowing out some large end-grain bowls - Manitoba Maple.




Due to the size, I dug out the Woodcut Pro-Form. Its set for a pretty aggressive cut.


Hollowing with this is incredible. It makes the longest curls I've ever seen.


However, when doing a long cut, it starts to "bounce" after a while, so I'm cutting ovals not circles.
The only solution I've found is to change angles and start again.

Does anyone have experience with these tools and how to hold a nice smooth cut?

Thanks

 

[Dennis J Gooding]

I spent a few hours hollowing out some large end-grain bowls - Manitoba Maple.
View attachment 21217

View attachment 21216

Due to the size, I dug out the Woodcut Pro-Form. Its set for a pretty aggressive cut.
View attachment 21215

Hollowing with this is incredible. It makes the longest curls I've ever seen.
View attachment 21214

However, when doing a long cut, it starts to "bounce" after a while, so I'm cutting ovals not circles.
The only solution I've found is to change angles and start again.

Does anyone have experience with these tools and how to hold a nice smooth cut?

Thanks

By "long cut" do you mean the cutter is extended a long way from the tool rest? Big shavings tend to imply large downward force on the tool and the problem may be that the tool bar is bending too much at the longer reaches. Try using a bowl tool rest if you have one. Failing that, adjust the tool for a smaller cut.

 

[olaf Vogel]

Sorry, it was a poor description. The problem is that the tool bounces left and right. This gets worse as the cut get longer, across the surface of the bowel.
I keep the tool rest as close as possible, with a maximum overhang of about 1.5".

 

[Bill Boehme]

I suspect the problem might be related to allowing the guarded cutter to control depth of cut rather than you controlling the depth of cut. I believe if you treat it as if it didn't have a guard (by minimizing tool pressure against the wood) the results will be better. Think of the guard as something that is keeping you out of trouble rather than depending on it to cut the wood as you wish it to be cut.

If too much tool pressure is applied to the wood in combination with not enough restraint in controlling its position then the tool will want to follow the path of least resistance as it cuts through the wood ... deeper in some places than others.

A guarded cutter doesn't give a precise depth of cut because as the wood is spinning, the hardness is varying, even when cutting an end grain piece. While the shavings may appear be be consistent in thickness and width, they really aren't exactly uniform. These tiny differences have a cumulative effect when you consider hundreds of revolutions. After a bit this uneven cutting will lead to tool bouncing and wood flexing.

 

[hockenbery]

When I have done endgrain pieces with ring tools, the hamlet hollower, or hook tool
I found hollowing first then turning the outside works best.

The thinner the wall the more important it is to hollow first.

I hollow center to rim while the pressure of hollowing is supported by the thick wall. I finde that these tools apply a lot more bevel pressure than a gouge.

The spindle orientation allows the outside to be cut quite nicely going rim to foot on the outside.
Also on light colored wood a light inside can bE used as a guide for a thin wall.

Whether it is a goblet, vase, or bowl I work the inside first.

 

[Bill Blasic]

My thought is that you are using too much pressure. My cutter is almost completely covered by the limiter, there is almost no feel when running your thumb over the cutter (I thought that there was no way it would cut wood with so little cutting surface exposed). I was so surprised how much wood that little exposed cutting surface cut and with so little pressure. Your cutter looks to be set very aggressive (which you also stated) and with a lot of pressure the chips may be deflecting off the surface pushing the tool away from the wood (don't know that for sure, just a guess). This tool works just as well whether side grain or end grain. I have not run into the problem you described using a soft wood or a hard wood and this tool removes a lot of stock in a hurry. Hope you figure it out.

 

[john lucas]

I don't own one of those but have used Hook, tools, ring tools, and the Hunter tools. I also get that problem with bowl gouges. Most of the time it's a hard spot in the wood and too much pressure on the tool that starts it. Then it becomes like chatter and each time you go over it, it gets worse. The solution has always been to take some light passes until you get it running true again and that will let you go back to your usual cutting.

 

[olaf Vogel]

A guarded cutter doesn't give a precise depth of cut because as the wood is spinning, the hardness is varying, even when cutting an end grain piece. While the shavings may appear be be consistent in thickness and width, they really aren't exactly uniform. These tiny differences have a cumulative effect when you consider hundreds of revolutions. After a bit this uneven cutting will lead to tool bouncing and wood flexing.

This explanation makes complete sense to me.
Since I;m hollowing out a bowl, its basically a pull-cut and a bit harder to control the feed rate, since I'm leaning over the lathe.
Also, there's no real bevel there, so its very sensitive to the angle.

My thought is that you are using too much pressure. My cutter is almost completely covered by the limiter, there is almost no feel when running your thumb over the cutter (I thought that there was no way it would cut wood with so little cutting surface exposed).

I suspect you are right. When I got it, the setting was very small (conservative). However, the cutter kept clogging. So I spent more time clearing it than cutting.
Hence the more aggressive setting and possibly the current issues I'm facing. I'll play around with it.

It is current great at removing large amounts quickly!


Thanks

 

[Bill Boehme]

... I suspect you are right. When I got it, the setting was very small (conservative). However, the cutter kept clogging. So I spent more time clearing it than cutting. ...

As Bill Blastic said, the problem is likely too much pressure and given that you said the cutter was clogging is an indication of that being the case. Try a very light touch where you are just barely touching the wood. If absolutely necessary open the guard up ever so slightly if the tool doesn't cut at all, but too much pressure will cause the tool to clog even with a large opening.

Let the tool do the work and cut at the rate that it wants to cut. As the cutter starts to get dull, you may unconsciously be increasing the amount of pressure without realizing it. Periodically ask yourself if you are "helping" the tool cut the wood.push it along is just another way to recognize that you are applying too much pressure.

Carbide cutters do get dull ... and much quicker than you are led to believe by the advertising.

 

[Leo Van Der Loo]

Olaf can you put a fulcrum on your rest ?, that should give YOU the leverage of holding your cutting tool and be able to move it in a controlled manner

 

[olaf Vogel]

Olaf can you put a fulcrum on your rest ?, that should give YOU the leverage of holding your cutting tool and be able to move it in a controlled manner

Similar to metal spinning lathes? Yes - I'm thinking about it.
My thoughts were to get a custom tool rest done, with the holes and pins. A guy down the road is a blacksmith, so might be able to weld up a tool rest for me. Especially since I now need one....

On the previous day I was turning large bowls from a nice chunk of Manitoba Maple, about 26" in dia and 12" thick.
I had it down about a third its original volume (and weight)

Guess I wasn't focused, got a bad catch, ripped the bowl loose from the chuck. It hit the tool rest, bounced off the wall, the ceiling, ripped just about everything off the wall, the light, the video monitor and my sanding machine.

Fortunately I was out of firing range (and cowering behind the tail stock).
Remember my DUCK and hide comment a few days ago? There was no attempt to catch this thing!
Its been years since I did anything similar - but admittedly my mojo was not working that weekend.

The bad news is that I managed to break the tool rest off the shank / quill.
Thats 1 3/8" thick!


The smartest thing was to go have lunch and beer and count my lucky stars.
An hour later, I went back out to clean up. To my surprise....the bowl was still ok!

I know wood is strong, but didnt know its that strong.

Fortunately I have a few other tool rests so I could get going again next day....on a different bowl.
The bouncing bowl has bad karma.

 

[Michael Nathal]

Lowering the RPM will reduce clogging also.

 

[Leo Van Der Loo]

Similar to metal spinning lathes? Yes - I'm thinking about it.
My thoughts were to get a custom tool rest done, with the holes and pins. A guy down the road is a blacksmith, so might be able to weld up a tool rest for me. Especially since I now need one....

On the previous day I was turning large bowls from a nice chunk of Manitoba Maple, about 26" in dia and 12" thick.
I had it down about a third its original volume (and weight)

Guess I wasn't focused, got a bad catch, ripped the bowl loose from the chuck. It hit the tool rest, bounced off the wall, the ceiling, ripped just about everything off the wall, the light, the video monitor and my sanding machine.

Fortunately I was out of firing range (and cowering behind the tail stock).
Remember my DUCK and hide comment a few days ago? There was no attempt to catch this thing!
Its been years since I did anything similar - but admittedly my mojo was not working that weekend.

The bad news is that I managed to break the tool rest off the shank / quill.
Thats 1 3/8" thick!
View attachment 21219

The smartest thing was to go have lunch and beer and count my lucky stars.
An hour later, I went back out to clean up. To my surprise....the bowl was still ok!

I know wood is strong, but didnt know its that strong.

Fortunately I have a few other tool rests so I could get going again next day....on a different bowl.
The bouncing bowl has bad karma.

Yes like in metal spinning, a toolrest for that is easily made, I made and used one to do some metal spinning.

I used a 1.5” X .5” flat stock and drilled some .5” holes in it to set the pins in, it worked OK for me.

It doesn’t have to be fancy for a trial, you can always make a better/nicer one if it works.

 

[RichColvin]

Similar to metal spinning lathes? Yes - I'm thinking about it.
My thoughts were to get a custom tool rest done, with the holes and pins. A guy down the road is a blacksmith, so might be able to weld up a tool rest for me. Especially since I now need one....

On the previous day I was turning large bowls from a nice chunk of Manitoba Maple, about 26" in dia and 12" thick.
I had it down about a third its original volume (and weight)

Guess I wasn't focused, got a bad catch, ripped the bowl loose from the chuck. It hit the tool rest, bounced off the wall, the ceiling, ripped just about everything off the wall, the light, the video monitor and my sanding machine.

Fortunately I was out of firing range (and cowering behind the tail stock).
Remember my DUCK and hide comment a few days ago? There was no attempt to catch this thing!
Its been years since I did anything similar - but admittedly my mojo was not working that weekend.

The bad news is that I managed to break the tool rest off the shank / quill.
Thats 1 3/8" thick!
View attachment 21219

The smartest thing was to go have lunch and beer and count my lucky stars.
An hour later, I went back out to clean up. To my surprise....the bowl was still ok!

I know wood is strong, but didnt know its that strong.

Fortunately I have a few other tool rests so I could get going again next day....on a different bowl.
The bouncing bowl has bad karma.

Olaf, I'm glad you were not hurt.

 

[Odie]

Guess I wasn't focused, got a bad catch, ripped the bowl loose from the chuck.

It's easy to lose concentration. Last time that happened to me, I was looking elsewhere, with one hand holding a gouge off the tool rest. I inadvertently touched the tip of the gouge into the spinning work piece. The gouge caught, and slammed into the tool rest. This was a couple years ago, but it jerked me back to reality pretty darn quick!

 

[john lucas]

Did the same thing and knocked the metal bar off the top of my Robust tool rest. Had to glue it back on. It's hard to be 100% perfect so sooner or later something is going to happen.

 

[Bill Boehme]

Guess I wasn't focused, got a bad catch, ripped the bowl loose from the chuck. It hit the tool rest, bounced off the wall, the ceiling, ripped just about everything off the wall, the light, the video monitor and my sanding machine.

You are very fortunate indeed to not have been seriously injured or killed. Even smarter than taking a break from the lathe would be to analyze why you had a catch that caused all this to happen. Consider ways to make the mounting method more "catch proof". For a piece that large, it seems like a large face plate would be a good choice. If not that then perhaps a Vicmarc chuck with 8" or 9" jaws.

 

[olaf Vogel]

You are very fortunate indeed to not have been seriously injured or killed. Even smarter than taking a break from the lathe would be to analyze why you had a catch that caused all this to happen.

Oh...it only took the first sip of cold beer to figure that one out.

I'm starting up a new FinTech company, scrambling for funding, head was buzzing with all sorts of stuff not related to woodturning...
THATS the proximate cause. Lack of focus. Coupled with a big chisel, and no tailstock.

Any time something major goes wrong, I take a step back and say "what just happened?".
I've raced bikes for years. You make a mistake, wipe out and then.....analyse.
There was always something that could have been done better.

Normally I turn wood to clear my mind, find that zen. Wasn't working that day.

 

[olaf Vogel]

Yes like in metal spinning, a toolrest for that is easily made, I made and used one to do some metal spinning.

I used a 1.5” X .5” flat stock and drilled some .5” holes in it to set the pins in, it worked OK for me.

It doesn’t have to be fancy for a trial, you can always make a better/nicer one if it works.

View attachment 21221 View attachment 21223

Hi Leo,

This morning I picked up the materials to make a few new tool rests.
- 1 1/4" rod for the post. (18" - enough for 3 posts)
- 2x2 angle iron, 1/4" thick (48")
- 1 x 3/4 rectangular stock
Total about $35

My blacksmith friend will do the welding (he owes me a few favours).

So we'll make one traditional rest, with heavy angle iron, about 18" wide.
Likely with the post offset to one side, so I can get deeper into the bowls.
Basically like this: https://i.ytimg.com/vi/7PvwLehDEdE/hqdefault.jpg

I'll skip the drill rod on top, for now. Try it out the basic idea first, before building the Mercedes version. I figure the drill rod can be added later, if needed. But we will add gussets at the post to provide additional stiffness and stability.

A second tool rest will be the metal spinning kind, similar to this:
http://www.sokolowskistudios.com/images/extras for cs/Tool Photos/T-Rest 4.jpg
I'll drill the holes before welding it up. Geometry similar to the first one, with gussets.

So one question is: what did you use as a pin? I assume needs to be something really strong.
My previous attempt used an old drill bit, cut off. That didn't last long.
I'll need to get the pin, figure out the hole size and drill this. To get the pin to stick and hold, I'm guessing the hole is slightly oversized, to about 3/4 down. Then undersized, to get swarf to drop through.

Thanks for the advice. BTW - I really like your metal ornaments. Will have to try that one day.

 

[Bill Boehme]

If you're metal spinning then you need a stout fulcrum to apply enough force to form the metal. In woodturning, the only use of a pin that I am familiar with is with my boring bar and for that purpose the pin only serves as as a guide. Using it as a fulcrum to apply a lot of force seems like a good way to knock a turning out of the chuck ... or did I miss something?

 

[hockenbery]

One more use of pins is in the mcnaughton center saver. The guide is basically a tool rest with pins.

 

[olaf Vogel]

If you're metal spinning then you need a stout fulcrum to apply enough force to form the metal. In woodturning, the only use of a pin that I am familiar with is with my boring bar and for that purpose the pin only serves as as a guide. Using it as a fulcrum to apply a lot of force seems like a good way to knock a turning out of the chuck ... or did I miss something?

As Leo suggested further up, if hollowing, it could allow a big more control, especially when going deeper inside.
I've seen variations on this theme

http://www.aroundthewoods.com/hookuse.shtml

The same idea is also used by Matt Moulthroup:

There are very few videos of their technique. This is the best one I've found.

All the references I've found are for larger, green turnings - which is what I like.

For out-of-round pieces or with varying density, I can imagine this would provide more lateral stability, which is why Leo suggested it - to help prevent the "bouncing" originally referred to. As for roughing out large pieces, lots of bark, inclusions etc, this may work well. But I would not want to apply more force - launching another bowl is not something I want to do.

If we're making custom tool rests, I figured might at well try it.

 

[Bill Boehme]

One more use of pins is in the mcnaughton center saver. The guide is basically a tool rest with pins.

I don't know why I forgot about the McNaughton Center Saver as I just recently bought that toy tool. However, the pins are used as a guide and not a fulcrum in the sense of using it as a pivot point to apply sideways force. If you try to use it as a fulcrum to guide the cutter sideways to change the course of the cutter, you will be greatly disappointed.

 

[Bill Boehme]

Olaf, I still think the bouncing that you are experiencing comes from applying a bit too much pressure against the wood ... causing it to flex a tiny bit. If you use the saddle or guide pin to overcome bouncing via the Armstrong method, my opinion is that it will lead to even worse things. If you find that things have gotten out of round, which is a real probability with green wood, then the guide pins are good for steadying the cutter while taking light cuts just clipping off the high points until things are back to being round.

I have a deep hollowing rig and a Rolly Munro guarded cutter that I typically use only to clean up the interior. The Rolly Munro cutter is similar to the Pro Forme. The hollowing rig has a flat top rest with a guide pin, but the only reason that I use the pin is to keep the boring bar from running into the far side of the opening and forcing a design opportunity.

I have a couple home made hook tools that I have used for freehand hollowing ... made from ⅜" O-1 drill rod. At my cautiously optimistic skill level, it's good for depths up to about eight inches. It's a real exciting tool to use until you get the hang of it and even then it's very unforgiving of a lapse in concentration.

 

[Leo Van Der Loo]

Hi Leo,

This morning I picked up the materials to make a few new tool rests.
- 1 1/4" rod for the post. (18" - enough for 3 posts)
- 2x2 angle iron, 1/4" thick (48")
- 1 x 3/4 rectangular stock
Total about $35

My blacksmith friend will do the welding (he owes me a few favours).

So we'll make one traditional rest, with heavy angle iron, about 18" wide.
Likely with the post offset to one side, so I can get deeper into the bowls.
Basically like this: https://i.ytimg.com/vi/7PvwLehDEdE/hqdefault.jpg

I'll skip the drill rod on top, for now. Try it out the basic idea first, before building the Mercedes version. I figure the drill rod can be added later, if needed. But we will add gussets at the post to provide additional stiffness and stability.

A second tool rest will be the metal spinning kind, similar to this:
http://www.sokolowskistudios.com/images/extras for cs/Tool Photos/T-Rest 4.jpg
I'll drill the holes before welding it up. Geometry similar to the first one, with gussets.

So one question is: what did you use as a pin? I assume needs to be something really strong.
My previous attempt used an old drill bit, cut off. That didn't last long.
I'll need to get the pin, figure out the hole size and drill this. To get the pin to stick and hold, I'm guessing the hole is slightly oversized, to about 3/4 down. Then undersized, to get swarf to drop through.

Thanks for the advice. BTW - I really like your metal ornaments. Will have to try that one day.

Olaf I used just some 1/2” steel pins, as for the small pieces I made don’t need that much pressure being thinner copper I softened up, and am able to get much closer to the work, needing less force on the fulcrum.

Of course you don’t need force for the wood turning, but being able to control the tool, so that you don’t have the tool taking more and less of a bite as you go from easier to harder to turn wood, as you had before.

Of course I might be optimistic of this working for you in your manner of turning, I’m sure we will hear of the outcome

 

[olaf Vogel]

Olaf, I still think the bouncing that you are experiencing comes from applying a bit too much pressure against the wood ... causing it to flex a tiny bit. If you use the saddle or guide pin to overcome bouncing via the Armstrong method, my opinion is that it will lead to even worse things. If you find that things have gotten out of round, which is a real probability with green wood, then the guide pins are good for steadying the cutter while taking light cuts just clipping off the high points until things are back to being round.

I have a deep hollowing rig and a Rolly Munro guarded cutter that I typically use only to clean up the interior. The Rolly Munro cutter is similar to the Pro Forme. The hollowing rig has a flat top rest with a guide pin, but the only reason that I use the pin is to keep the boring bar from running into the far side of the opening and forcing a design opportunity.

I have a couple home made hook tools that I have used for freehand hollowing ... made from ⅜" O-1 drill rod. At my cautiously optimistic skill level, it's good for depths up to about eight inches. It's a real exciting tool to use until you get the hang of it and even then it's very unforgiving of a lapse in concentration.

Hi Bill,

When I first started with the Pro-Form, it clogged like crazy. As I widened the gap it started to cut clean. Maybe its the different texture of green wood vs. dry wood. I agree that my settings on the tool are likely too aggressive. So I'll play with it to reduce the gap and get a lighter cut and see if it will still clear the curls.

Additionally, Pro-Form seem to sell (re-sell?) a Gate by Phil Irons, with this. Possibly this is just an issue with such a tool.

View: https://www.youtube.com/watch?v=fx_bZzpmM1s


The other appealing feature is to be able to move that gate further inside the open vessel while turning. Currently if I turn in my tool rest to do the same, it means my left hand is inside...a large, fast spinning block of wood. Not that comforting. If I can get the gate (or pin) to provide stability, near the end of the rest, that would provide a greater safety margin. Which, I think, is was you are saying with the Munro cutter. It would also take the stress off my hand. Since these are end grain bowls, a push cut (left to right) would not be a great solution.


Right now, I have to set the banjo perilously close to the edge of the bowl. So this might help as well.

Lastly, I would like to try having a pin, for stability, while roughing in a blank like Matt does here at about 2:00.

View: https://www.youtube.com/watch?v=cj5pg7B5VWg

Currently, at this stage I'm using a heavy flat scrapper, or a Thompson 3/4" gouge, flat. Both transmit a lot of shock. Matt uses the gouge more on angle for a cleaner, easier cut. But that results in lots of side load and more shock than I can hold by hand.

 

[hockenbery]

Currently, at this stage I'm using a heavy flat scrapper, or a Thompson 3/4" gouge, flat. Both transmit a lot of shock. Matt uses the gouge more on angle for a cleaner, easier cut. But that results in lots of side load and more shock than I can hold by hand.

I find that scraping transmits a lot of shock and is the one cut that requires me to exert a lot of effort.
Scraping tends to beat me up so I avoid scraping except for finishing touch up.

Moulthrop appears to be doing a flute up shear cut. Very advanced. This is a bevel riding cut on the front wing of the tool. All the force goes into the tool rest so a light grip on tool and no shock. He is working far off the rest and the pin seems help him make a bigger cut than I would. If I'm working 4" over the rest I have to take small cuts or the gouge gets pulled from the increased bevel pressure. And a slight chatter begins to develop and turn into a bigger chatter.

I do a lot of hollow forms similar in shape in the 10-14" diameter range. No shock to my body on the outside with the Ellsworth gouge. No shock in hollowing with the Jamieson bar.

 

[olaf Vogel]

The bad news is that I managed to break the tool rest off the shank / quill.
Thats 1 3/8" thick!
View attachment 21219

My friendly blacksmith dropped off the new tool rest today.

Quite impressed. Don't think that will break. Its about 15 lbs at 18" wide.
I asked for some gussets at the post for extra support as well.

The post is deliberately off centre, so I can push the right side into a bowl further.





Spray on a little paint and give it at try on the weekend.

Some sites added drill rod on top. I figured for the first attempt, keep it simple and see if the drill rod is needed. Its 1/4" thick angle iron, so hopefully strong enough.

If its successful, then there are few other designs I'll try as mentioned above.
So it cost me, $30 in steel, (2/3 still left over) and a old 1 hp repulsion motor.

Looking forward to trying it on the weekend.

 

[Bill Boehme]

I would suggest a design improvement to the homemade tool rest if you have another one made that I saw a production turner use for long spindles like balusters. Have it made like an inverted V. It will offer a couple advantages. First, it will allow you to lower the rest further down than the current configuration and second, you will be able to drop the handle down further for shear cutting.

Even better, instead of the angle iron make something similar to what I use that is made by Steve Sinner (or buy one ready made from him). I have lots of tool rests, but this is what I use almost exclusively.