Thursday, December 19, 2013

Drawknife Rehab - Part 3


This will be a much shorter post today.  I mentioned in the last post that I put the ferrells and caps into 5% acidity vinegar to finish removing the rust on the inside surfaces.  Within minutes there were bubbles forming on the pieces and the rust particles were floating in the vinegar within an hour.  These four pieces remained in the vinegar for 30 hours.  I then rinsed them in tap water, filled the jar with water and added baking soda to it.  As for how much, well I used a very old scientific method, Gravity!  When a clump fell out of the box that was the amount used.  This is just to neutralize any remaining acid from the vinegar.


First 15 minutes in vinegar

After 30 hours in vinegar

In solution of water and baking soda
 After drying the pieces off I wire brushed inside and out and coated with protective oil.  Hint: a 1/2" plumbers brush was just the ticket for doing the inside of the ferrells.


I also measured the flair of the tangs on the drawknife today and determined I will need to make some adjustments to them before replacing the handles.  The tangs for the most part are in line with the blade making it a drawknife best used as a bevel down knife.  Just what I want.



I will check the angles on one of my favorite drawknives and most likely adjust this knife to match as closely as possible.  My instinct tells me it should be fairly close to the 83.75 degrees pictured above.

The last post has had some great reader comments.  I greatly appreciate that you take the time to read my blog and even more so that you take the time and effort to contribute with your comments.  One concern brought to light by a reader was Hydrogen Embrittlement.  There have been some wonderful contributions concerning this and they can be found in the last posts comments.

~ Ray Schwanenberger

Wednesday, December 18, 2013

Drawknife Rehab - Part 2

As luck would have it, just as I was making great progress on this project, I had to go out to work.  I guess that is how it is when one is semi-retired.  In an attempt to be as thorough as I can this will be a rather lengthy post.

Well I'm back and lets take up where I left off a few weeks ago.  I searched the shop and house for the materials needed to remove the rust using electrolysis and the only thing I had was the baking soda.  I purchased a plastic container to use as the electrolysis tank, 8' of 1/2" rebar to use as sacrificial steel, rebar tie wire to connect the rebar together and to tie to the drawknife so that it could be suspended in the tank, and the total cost was less than $12.  I borrowed the battery charger from my neighbor Rusty (isn't that ironic).



First step was to wire the rebar together as evenly spaced around the tank as possible.  All my research indicated that removing rust using electrolysis is a point to point process.  So to avoid any shadowed or blind spots the drawknife needed to be surrounded by the sacrificial steel.  The longer piece of rebar on the left is where I clamp the positive side of the battery charger making the rebar the anode.


Next I filled the tank with water and added 1 tablespoon of baking soda per gallon of water.  Mix this thoroughly, stirring until the solution is clear.  This is the alkaline solution needed.  Some individuals recommended using sodium bicarbonate NaHCO3 (baking soda) while others recommended using sodium carbonate Na2CO3 (Arm & Hammer Super Wash).  I am not a chemist and I know that there is a difference between the two, but I'm not sure exactly what the difference is in regards to removing rust using electrolysis.  By the way, both camps results were the same, the rust was removed.  So the deciding factor was, the baking soda was in the pantry.  I then wired the drawknife to a piece of wood and submerged it in the tank.  The drawknife will be the cathode once the negative cable of the battery charger is attached.


Take great care to ensure the drawknife or any other parts do not come into contact with the rebar!  Next, I attached the positive cable to the rebar and the negative cable of the battery charger to one of the wires around the drawknife.  I made sure that both cable clamps were out of the water.  Once I ensured that everything was as it should be I plugged it in.  Almost immediately I saw a reaction take place.  Another word of caution: If for any reason you should have to move anything in the tank unplug the battery charger first!



After 32 hours I had to remove the drawknife from the tank.  At that point in time it appeared that 99% of the red rust was removed from the drawknife.  The ferrells and caps however still had a bit of rust remaining, especially on the inside of the ferrells.  I rinsed off the drawknife, ferrells and caps while wire brushing them, then I coated them with a protective layer of oil.


There is a good bit of pitting from the rust, hopefully it will take a good edge.

Red rust is removed and the black rust is stabilized and adhered to good metal.

Name stamped into the drawknife was preserved because electrolysis was used to remove the rust.

Metal Protection from Felder, good stuff!

The sludge that remained in the tank was gnarly looking.  The rebar had collected the rust just like it was supposed to.


Earlier today I cleaned the protective coating off the caps and ferrells.  I then placed them in a glass jar covering them with vinegar (5% acidity).  I will remove them in the morning, rinse them with water, then put them back in the jar covering the pieces with a mixture of water and backing soda.  I will leave them in this mixture for a few minutes to neutralize any remaining vinegar then wire brush them.  Hopefully this will remove the remaining rust and I can apply the protective oil.

If I am unable to get a post made prior to Christmas my family and I would like to wish you a very Merry Christmas and a safe and prosperous New Year.


~ Ray Schwanenberger

Friday, November 29, 2013

Drawknife Rehab - Part 1

I hope that everyone had a very enjoyable and blessed Thanksgiving!

It has been all too long since I have taken the time to make a post, and for this I apologize.  It seems life happens and some things have to take a back seat.  I will be making every effort to be more consistent with my posts and hope that you find them interesting and of some use.
  
The other morning we opened the blinds to find 1 1/2" of the perfect snow.  It was everywhere except on the concrete.  There is something about fall and winter that make me want to be in the shop.  After getting the shop back in order, I was looking over three of my older drawknives and decided it was time to do something with the ugly duckling of the lot (the knife on the far left).  The handles are loose, the blade is rusted and even has a bit of a chunk out of the cutting edge.  I thought this would be a good knife to use in my first attempt at a total rehab.  Then I thought it might be interesting to share this unrehearsed attempt at making this a usable tool.


The handles on the middle knife are my preferred shape of handle.  Oddly enough one of these handles measures an 1 1/2" in the bulb while the other measures 1 3/8".  I find the smaller of the two fit very comfortably in my hand and I don't experience hand cramps or fatigue like I do with the handles on my subject knife.  That made the decision to remove the handles easy.


I have an old orange plastic handled chisel I keep around the shop for jobs such as this.  Knowing the handle tang extends the entire length of the handle I did not want to damage the edge of one of my good chisels, so broke out ole orange.  This is what I discovered.  The hole is step drilled to accommodate the transition from a tang that resembles an over grown cut nail, to round.

The fit of the ferrel and the cap were tight, as was the round portion of the handle tang.  However, as you can see, the upper or larger portion of the step drilled hole was no where close to being tight.  This brings some questions to mind (i.e. another rabbit hole to explore), but not at this time.


The next step is to remove the rust.  After a little research I have decided to remove the rust by electrolysis.  I decided to go down this rabbit hole in hopes of converting the black rust into a more stable state and removing the red rust.  This is done by passing a low voltage DC electrical current through an alkaline solution or electrolyte.  The rusted knife will be submerged into the solution acting as the cathode (negative) and the sacrificial steel will be the anode (positive).  I found the site of a gentleman by the name of Andrew Westcott that I found very enlightening on the subject.

I am now going in search of the materials needed to set up my electrolysis tank.  I do hope I have most of it hanging around the shop, I do not want to have to deal with the Black Friday traffic.  Stay tuned for Part 2.


~ Ray Schwanenberger

Saturday, June 1, 2013

What Is This Tool Before Me


This was acquired by my brother-in-law Rick at a yard sale for $3.  The seller claimed it to be a "scoop adze". 

This is a mystery to me!  This tool exhibits the tell tale signs of being made by a blacksmith. It is about 12" long from the hammer face to the end of what the seller said is an adze. 

If anyone knows what this is and has some historical data on it please let me know by posting a comment. 






Wednesday, May 22, 2013

What in the Wide World of Sports Is A Goin' On Here?

Those of you who know me, know that I can be a bit of a practical joker.  Well the last one bit me in the hind quarters.  Suffice it to say that a crank call to an old friend and colleague resulted in a job offer that I could not refuse.  So on May 6th I came out of retirement and went back to work, with a "very flexible" schedule.



In a previous post I mentioned I was able to get the dye stain on the king size bed before leaving town.  After being gone for two weeks I returned to the shop to apply the brown mahogany stain.  I applied said stain, allowed it to sit and then wipe off the excess, as per the instructions.  Much to my dismay it looked nothing like the sample board made with the exact same dye and stain.  It had a much redder appearance.  See post title for the family friendly version of my reaction.  I spent the next 2 1/2 hours with a maroon pad and water (water based stain) stripping off the newly applied stain.  

It was upon the completion of the aforementioned stripping I swore (and I mean I swore) off all woodworking except for building chairs.  It was obvious to my wonderful wife that I was in need of an intervention.  She quickly appeared at the shop door with an icy cold Land Shark and talked me off the the headboard ledge.  Two days later, an appropriate cooling off period and time to allow everything to dry completely, I was ready to attack staining again.

  
This time I stained a small area and immediately wiped off the excess.  The results were so close to the sample I deemed it a success.  After allowing the stain to dry for 24 hours, it has been quite humid here in Kentucky, I sealed it with wax free shellac.  Later today or tomorrow, I will go over the entire piece with a very fine pad and apply a thin coat of satin poly.  I did this with the sample board and the results were a semi-gloss sheen that Carol and I like.

I did say a few weeks back that the subjects of future posts might be a bit different.  Working out of town quite a bit will keep me away from my shop more than I would like.  After many a conversation with my brother-in-law Rick, I offered to help him finish setting up his shop in the evening after work.  As a result, I will have access to a "Satellite Shop" while I am away from home.  Rick is a very talented individual and artist who is not afraid to try anything.  I look forward to working in Rick's shop.  A hint of what the future may hold is pictured below.  By the way this is the result of one of those conversations.



      

~ Ray Schwanenberger

Friday, May 3, 2013

Method of Work

While I am away from the shop I have been thinking about the most efficient way of working when building case goods, beds, and things other than chairs. With Windsor chairs my process is pretty straight forward. Split the log, work the spindles to an octagon shape, shape the arm and bow (if building a Sack Back) and bend in the forms, then set to dry. Leg and stretcher billets are turned out of stock that was split and turned round to dry. While all parts dry, I carve the seat, and so on.

However, with things other than chairs, I usually put on paper my little sketch with some dimensions and into the shop I go. Man do I save time on the front end! I choose my material and I begin. I get the framework of the piece built and then build the details in accordance to what the newly constructed frame work calls for. Sounds fairly easy and straight forward does it not? Suffice it to say, things are not as they seem in my somewhat wonky mind.

With this method, I end up doing so many different machine set-ups it is unbelievable. As you can imagine this can result in minuscule discrepancies in measurement accuracy, which in turn leads to woodworker frustration, and results in me writing this blog post.

I have sought professional help for this malady and here is the advice I have received, as I heard it. Start with as accurate of a drawing as possible. Time to learn Sketch-Up! Develop a cut list, to prove the piece can be built and to purchase material. Take time and think about how to efficiently break down the material with minimal machine set-ups. THEN begin building! Build the carcass, dispose of the cut list, and finish with the remaining parts.

I hope I understand the advice I have been given but more importantly I must fight the urge to skip the prep work. I wonder if there is a support group out there?

Thursday, May 2, 2013

A Great Cause and Working At New Heights



Allow me tell you about a very good thing I was made aware of the other day.  It is a project being put together by woodworker and blogger Sam Cappo.  Sam is putting together a user set of tools, building a tool chest and then giving it all away to a deserving woodworker.  If you have any extra tools, please consider donating.  To view a list of sought after tools and all the details of this project go to Sam's blog, PlaneDetails.com



Yes this is a first, building furniture from a ladder.  I needed to let in the bed rail hardware and this was the easiest way to accomplish said task.  These rails are 82 1/2" long and there was just no other good way, that I could think of, to balance my palm router. Thank goodness it is hidden.


Because the first coat of the stain is a water based dye stain and I had done some sanding, I needed to raise the grain prior to dying/staining.  After the wood had dried I discovered these little spots.  They looked like rust spots.  I can only assume they are the result of water mixing with some type of mineral in the wood.

After I knocked the fuzz off with 320 grit paper they disappeared, and did not reappear with the first coat of dye stain.

  

Here is a look after the first coat.  I used General Finishes Light Brown Dye Stain for the first coat.  I will follow that with GF Brown Mahogany pigment stain.  This will obscure the grain to some degree but it will allow me to even out the color and hide some of the mineral stains that are within the wood.

Due to my schedule it will be a couple of weeks before I will be able to apply the second coat and top coat to finish this project.  Before I move this monster into our bedroom I will get some studio pics taken of it along with the Continuous Arm Windsor.

My next project and blog subject is going to be a bit different so stay tuned.

~ Ray Schwanenberger

Monday, April 29, 2013

Projects In The Works

I heard from a friend the other day wondering if I was still blogging about my chair making and woodworking.  Yes I am, but obviously I am not doing a very good job of it.  I get so involved in the project at hand that I totally space out on making posts about it.  So this is to catch-up on what I have been doing.


My wife and I agreed we wanted to try a different color milk paint on the Continuous Arm Windsor.  This also afforded me the opportunity to try General Finishes Milk Paint for the first time.  I am doing a two color painting, still going for a mottled look, similar to the black over red I have used on my other chairs.  The first coat, pictured above, is Federal Blue.  This will be covered with a darker Coastal Blue wash coat.  Because I am using two shades of blue, I doubt the mottled appearance will be as dramatic as the black over red.  I will post more pictures in my next post (it won't be in a month I promise) along with my thoughts on the GF milk paint. 


One of the projects on my "Honey-Do-List" is a proper bed frame for our new Sleep Number Bed.  The material is from an Ash tree that had been blown over when a tropical storm had come through our area a few years back.  The tree yielded just shy of 1000 bd. ft. of beautiful material.  This tree has provided the material for my bench, shave horse, a Welsh Stick Chair and now the king size bed and two night stands, yet to be started.  It will be interesting to see just how much furniture I will be able to make from just this one tree.


The two pictures above are the dry fitting and glue-up of the head and foot board.  I did not have material wide enough for the panels so I re-sawed the material then did the glue up.  I wanted to have an interesting, but not overwhelming, flow of the grain pattern from one panel to the next.

The glue up is almost complete.  All that is left to do is install the top boards and prep the side boards for hardware.  Then I will do one last dry fit/assembly to ensure everything is copacetic before applying the finish.  By the way Ash is a heavy wood and it is going to be an adventure getting this headboard upstairs.  Ready the ibuprofen! 

~ Ray Schwanenberger

Tuesday, March 26, 2013

Chairmaker's Mecca

For many of us who make Windsor chairs, Jonesborough Tennessee is a Mecca. Not because there is a treasure trove of antique Windsors, but because there is a treasure in Curtis Buchanan. This very unassuming and humble man has drawn many a Chairmaker, novice and experienced, to this beautiful little hamlet in the mountains of East Tennessee.

Down the gravel path, past his garden, is where the magic happens. This is where I am spending my week, learning from the man I consider to be the best. I will be writing more detailed posts on the class and my experiences during my time with Curtis, so stay tuned.



Wednesday, March 20, 2013

Happy St. Sharpening Day


Yes it is sharpening day in the shop, in preparation for class next week.  While no one likes to sharpen, it is an evil necessity.  While I was trudging along I began to wonder how others sharpen and what systems they might use.


 

I recently checked where the blog is being read and it amazed me that so many people from all over the world have been giving it a look, Vietnam, really?  So what sharpening system/s do you use?  If you would be so kind as to leave a brief comment, here on the blog, about the system/s you use and why it works best for you, I would be curious to see the different opinions.

~ Ray Schwanenberger

Friday, March 15, 2013

The Leather Attache' And A Road Trip

Lets talk leather first.  Yes I was able to snap a shot of the Jedi Leather Master (JLM) Ty Black, who brought by the prototype of the Leather Attache'  and I must say it is sweet!  This is not your ordinary run of the mill leather tool roll.  Ty really put some thought into the design of this piece. 


When the flap is folded back and the Attache' is draped over a board as pictured below, accessing the tools is extremely easy.  As you can see it is very easy to determine what tool is where with this design.  When the Attache' is laid flat the blades of the tools are completely concealed between the alternating pockets on the opposite side, providing maximum protection.

This Crazy Horse leather is so very nice.  Ty crafted the 12 pockets to nicely fit my chisels,carving tools, and even my new Galbert 6 degree reamer.  This will make traveling with these essential tools easy and worry free.

Now for the latest road trip.  On Monday I made the four hour trek to the shop of Tennessee Windsor Chairmaker Greg Pennington.  I left my northern Kentucky home, in the Eastern Time Zone, at 5:00 AM to arrive at Greg's shop in Hendersonville, by 9:00 AM.  About half way to Louisville I remembered that Greg lives in the Central Time Zone, insert V8 head slap!  I traveled the four hours, each way, to learn some new turning skills and how to turn the all so sexy Baluster leg and arm post, the way Greg turns them.


I was once told if you want to know how to do something, ask a person that does what you want to do.  In adherence to that sage advice I try to take at least one or two classes a year to learn from the experts.  Greg is one of these experts.  Greg received the majority of his training from two people I consider to be the best in the business; Curtis Buchanan and Pete Galbert.  Besides teaching classes in his own shop, Greg assists Pete with his teaching at The Marc Adams School of Woodworking and The Kelly Mehler School of Woodworking.

I have to say that Greg meets all of the qualifications of "All Around Nice Guy".  Like Curtis and Pete, Greg is very giving of his knowledge and information to help his students succeed.  I will be making the trip back to Hendersonville again for another class with Greg.  If you have never seen Greg's work stop by his web site and or his blog and take a look.

During the day Greg's friend Bill showed up at the shop.  Bill is the gentleman that milled all the timbers and more for Greg's magnificent shop.

 
As for my class with Greg, there were a few skew catches, read soiling my britches, and  a gouge corkscrewing or two.  However, I felt like I was starting to get the feel for it when I had to start thinking about heading home.  After working with Greg until almost 6:00 EST/5:00 CST I headed north.  The 4 hour trek home seemed to go by quickly.  My thoughts were consumed by the images of the warm and welcoming shop and all the great things I had learned.  Thank you Greg and Bill for making this a wonderful experience.


~ Ray Schwanenberger

Wednesday, March 13, 2013

Oh Sweet Leather

Last week Ty Black stopped by the shop to bring by some leather goods and to play with Matilda.  Being a chair maker the scorp is a tool that I can not do without.  Protecting the edge, and my fingers, of a sharp scorp is difficult to do, unless one knows a person that is proficient in making such devices.  This is where Ty comes in.  Besides being a woodworker, Ty is an excellent leather-smith.


Above is the scorp sheath entirely hand stitched.  I witnessed this process while Ty was making an adaptation, lets just say I think I will stick to working wood.  He also went the extra mile and made me a scraper wallet and a block plane holster.


I am looking forward to getting the finished Tool Attache' made of Crazy Horse Leather.  If you need some leather tool protection, drop Ty an email, you won't be disappointed.

~ Ray Schwanenberger

Thursday, March 7, 2013

Missing In Action

It has been a month to the day since I last made a post, WOW how time flies.  I was released by the doctor to return to the shop and have been busy ever since.  So this is what has been going on.

I went back to work on the bed I'm making for Carol and me and after the long lay off I had to bring the parts back into true.  Deciding on the finish has taken quite some time.  Finishing not being a strong point of mine, I decided to dive into Bob Flexner's book "Understanding Wood Finishing" and rectify that situation, at least partially.  Some of the quarter sawn ash, I had been air drying for 2 years, had some spalting and needed to be covered by the stain and or dye.  So began the experimentation.



It took a total of 22 recipes before we were able to find one that we could agree on and that covered the spalting.  I will make a post later on recipes.  I will say this, the good folks at General Finishes are a great source of information and an absolute joy to work with.  When I called I expected to get "For this department press....", instead a real live human answered, and she was able to answer all my questions and offered some really great suggestions.

I used the badly spalted ash, pictured below, for my test pieces.  I figured if this could be covered the very minor spalting on the bed components would cover with no problem. 



A picture is worth a thousand words, they say. 


I promise my next post will be sooner than a month and it will include "Leather"!


~ Ray Schwanenberger

Thursday, February 7, 2013

Physical Therapy: Dovetails & Practice



I have been getting a wee bit antsy about getting back to the bench.  So yesterday I thought I would do a little physical therapy to take off the edge.  This came in the form of dovetails and practice.  I surmised what better therapy for a recovering shoulder than a little light sawing.  It has been close to nine months since I last cut dovetails and I figured I needed to knock the rust off of that skill.



In keeping with my goal for this blog, I thought I would share some of my thoughts, no matter how psycho-pathetic they may be, on practicing woodworking skills.  Sounds odd I know but stick with me for a moment!  Think about this; a guitarist doesn’t learn to play a song like Hotel California without first practicing and learning some basic skills.  First they must learn and practice chords and chord changes while keeping time.  It is only after the basic skills are learned that the musician can move forward with learning songs.  So why do we as woodworkers attempt to build things without first practicing and learning the basics?


Quality shop time is hard to come by for many of us, so why not make the most of the little time you have.  Practicing basic skills can help greatly in this area.  It has been my experience that a little time spent practicing a basic skill prior to building a project pays off in many ways.  I rarely ruin material anymore and the time it takes to complete a project is dramatically decreased.  By taking time to correctly practice these basic skills they have become second nature allowing me to concentrate solely on the project at hand.


Sawing is a critical and basic skill required to properly cut dovetails.  When I first started cutting dovetails by hand I took 10 – 15 minutes a day for a week and practiced rip sawing to a line perpendicular to the board and angled while stopping on a scribed line.  In the same practice session I practiced rip sawing perpendicular and a vertically while stopping on a scribed line.  These are the basic sawing skills needed to accurately saw pins and tails.




If it has been awhile since you last performed a specific skill, like it was for me in cutting dovetails, do some warm-up practice before jumping straight into your project and risking ruining your material.  I took my own advice and practiced the two exercises as pictured above.  As a result the dovetails I cut were pretty good.  It wasn’t great because I need to sharpen my chisels, but that is another post.




So if you only have 15 – 20 minutes don’t blow off going into the shop.  Grab some cutoffs, your saw and marking implements and practice these sawing skills or whatever basic skills are required for the project currently on your bench.  I guarantee it is worth the effort and you will be amazed at the results.  I know I was!

~ Ray Schwanenberger

Monday, February 4, 2013

What The Heck Are They Thinking?



Over the last few weeks I have discovered that many of the people purchasing the tools I have been selling are new to woodworking or just entering the arena of hand tool woodworking.  I have also read many posts of late asking what tools are needed, both hand and power, to get started into woodworking.  Many of the responses were from very talented amateur woodworkers and some were from well publicized professional woodworkers.  I was amazed that nary a one of the respondents asked what type of woodworking the person did or wanted to do.  Every one of these well intentioned respondents started spewing out a list of tools they thought the person needed.
 
This got the ole glue pot of gray matter warmed up and I wondered how I would answer the question.  Then, while preparing the shop for my return, it hit me; what the heck are these people thinking?  I could not believe that not one individual mentioned what I now consider to be the foundation, the rock on which all good furniture is built; The Venerable Bench!
Yes the much overlooked and taken for granted bench.  A proper bench made for the type of work you do!  In my humble opinion, this is the foundation for success as a woodworker.  One must have a way to secure their work so the tools, paid for with hard earned cash, may be used to their fullest capabilities.  I have worked on a torsion box precariously perched on saw horses and I have worked on a solid core door attached to a chest of drawers, my Hillbilly Shaker period.  Now I work on the proper type benches for the work I do. 
 
Yes I said benches; I build chairs and furniture so I prefer two different methods of holding my work. Before I built my bench I did some research, to see what best suited my needs.  I read “The Workbench Book” by Scott Landis, and “Workbenches from Design & Theory to Construction & Use” by Christopher Schwarz.



This is the bench I decided upon and use the majority of the time.  It is my version of the French Bench or Roubo Bench as it is also called.  Unless one is a full grown male silver-back attempting to push a dull scrub plane through 100 year old Tamboti, this behemoth will not easily skate across the floor.  This bench weighs in at an estimated 350 pounds and is rock solid under the heaviest of hand plane use.  The work is securely clamped to the top or the face of the bench using the vises or holdfasts or a combination of the two.  With this bench I have experienced projects being completed quicker and to a higher degree of quality.



This is my other work holding tool, a shave horse.  It is a very specialized bench that the majority of woodworkers will never use.  This is a tool used mostly by greenwood workers and chair makers.  I build Windsor chairs and this is the ideal tool for shaping the various parts for my chairs due to the ease with which I am able to clamp and release the work.

Well the ole glue pot is cooling down, so I will finish by asking this of you; the next time someone new to the craft, or anyone for that matter, asks for your opinion on what tools they should start with, do them a favor and save them the misery of working on some contrived contraption of a bench.  Ask them what type of woodworking they are going to do, then advise them to start by building a proper bench best suited to the work they want to do.

-         Ray Schwanenberger