The "Lathest" News
March 2013                    Issue #38
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In This Issue  

In this issue Brian gives us a comprehensive description of how he can easily turn a deep, wide and thick end grain vase.  In past issues he has walked us though the steps to turn deep thin walled pieces as well as some smaller natural edge vases. We have had some suggestions that the articles have not covered all of the aspects and capabilities of using a large boring bar.  Brian has covered all the bases in this article.

 

As well, you will notice our Large Captive Boring Bar System promotion.  Our passion has always been turning and it is our intention to dial back the tool manufacturing and distribution.  If you are considering the purchase of our Captive Boring Bar System, 'round up a buddy as we are offering 2 for 1 until they have sold out.  Don't delay - once they are gone, they are gone!

 

  

 

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Deep Hollowing Thick Vessels with the 

Large Captive Boring Bar

by Brian McEvoy

 

  Since Frank Sudol first introduced me to the large captive boring bar I'm sure I've turned at least a thousand deep vessels ranging from 8 inches to well over four feet.  To this day I'm still impressed with the capabilities of such a simple turning tool and I probably still have as much fun today as I did when I turned the first piece a dozen or so years ago in Frank's workshop.  There are a number of different systems on the market and all have their place and limited capabilities.  The two main differences between Frank's and all of the others is the fact that the back rest isn't attached to the lathe and the boring bar itself was 1½ inch solid cold rolled steel weighing in at 50 pounds.  The extra weight was a no brainer when considering reaching in deep over the tool rest.  I soon discovered that though a 1" bar worked well for not-so-deep vessels, it left me struggling with anything over 12 inches or so.  The best thing with the 1½" bar is that I can turn smaller pieces with ease, just as the deep ones.  With the 1" bars I can only turn the small vessels, so why spend my money buying a smaller unit with very limited capabilities?

 

 

The back rest/floor stand was also an issue with many of the projects I worked on.  A problem with a back rest that attaches to the lathe bed is that it limits the angle of the boring bar, therefore preventing me from producing wide vessels with small openings, particularly if I wanted to undercut the inside top.  A floor stand back rest can be swung virtually at right angles to the opening, giving you the angle necessary for many designs.  As well, back rests that attach to the lathe bed limit the depth of the vase to a greater extent, in particular on those with shorter lathe beds.

Fortunately, I've had the pleasure of travelling extensively demonstrating the advantages of the large captive boring bar.  I've found that many people are intimidated by the size of a large system, so having the opportunity to demonstrate the ease of use has, to my delight, opened creative doors for many more woodturners.  One of the problems while demonstrating was there wasn't a source for these units.  The more mechanically ambitious folks were taking pictures and drawing diagrams to produce their own.  Besides the machining and welding aspects, it was quite a nuisance rounding up all the necessary parts and pieces including cutters, cutter holders, leveling feet, rollers and the 10 plus different sizes of steel needed to complete the job.

 

Though it was never my intention to get into the tool manufacturing and distribution business, and after numerous attempts to no avail to find someone else to manufacture and distribute them, I finally decided to go ahead and have some manufactured.  I was fortunate that my woodturning buddy Gord Langer was just as enthusiastic as I was, so we put our heads and money together and soon had a beautiful captive boring bar system available for the market.  Now after about five years and many happy turners, both Gord and I have decided we want to concentrate our time and effort on turning rather than manufacturing and distributing tools.  For this reason we have decided to clear out the balance of our inventory at fire sale prices.  Please note that we will not be manufacturing these systems in the future.  Rather than giving a discount, we want to encourage you to get together with a turning buddy and order two complete packages for the price of one.  Let me assure you that you'll have a hard time buying the material at this price.  We will continue to offer for sale all of our smaller items such as cutters, extended reach cutter holders, light kits, instructional DVDs, as well as the Elio Safe Drives and piercing equipment.   

 

  

 

 

To get started we need logs, so dig them out of the snow (unless you are lucky enough to be in Florida!). This birch tree was cut late last fall then tarped and left to stay frozen so the logs would be nice and fresh when needed. This is providing they will used before the spring thaw. I've cut it to length, allowing extra for the mounting screws and to square up the end that the faceplate will be screwed onto. 

 

 

 

 

Mark the center on both ends and study the log to determine which end has the least defects.  This will be the top.   

I try to avoid logs that have sections with lots of knots or other defects.  These deficiencies when turning end grain are sure to cause grief while drying.  

  

 

 

 

 

 

   

This log probably weighs 60 lbs. so I find it much easier to place an appropriate size block on the lathe bed to support it while I'm mounting it between centers.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Use your favorite drive to mount on the spindle; in this case I will use a 2 ½ inch Elio Drive. I do use this for for logs ranging up to a few hundred pounds.  For the logs larger than that I'll pull out my 3½ incher.  The 2", 2 -1/2" and 3-1/2"Elio Drives are available on our web-sites.

  

Move the tail stock in place; note I've mounted the log with what is going to be the bottom of the vessel on the tailstock end.  I've done this so I can square up the end in order to mount the face plate; this will make more sense as we proceed.  If working with a timber that the bark will peel off easily, take a knife and make a cut from one end to the other.  In this case I can peel one continuous sheet of birch bark.  If the bark can't be peeled off, turning it off is fine, just a little more work.  Notice I've left the one ugly knot on the bottom as this will be removed later as part of the waste wood.

 

 

 

 

 

 

 

 

 

 

 

Start your lathe off slowly and roughly square up the outside, just until it's running true; then square up the bottom and remove from the lathe.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I always recommend overkill with the screws.  In this case I'm using 12 #14 2½ inch screws.  An impact drill drives these large screws like they were going into butter.  A good heavy duty face plate when you're working with heavy timber is highly recommended.  I haven't found any as good as the Oneway face plates.

 

 

 

With the lathe running at the slowest possible, just guide the faceplate onto the spindle and tighten.

 

 

 

 

 

 

 

 

 

 

 

Square up the log again as it will be a little out of round after transferring it to the face plate.  

 

I just use the edge of a large bowl gouge to roughly turn the top section of the form I desire.  Don't get carried away with the fun of the chips flying and remove the mass of wood from the bottom half.  For the most part leave the bottom half alone until you've turned out a quarter of the inside.

 

Finish forming the top third or so; a cabinet scraper works well to smooth out any imperfections.

Use a saw tooth forstner bit to bore out a depth hole.  One at least as large as the drill chuck will be necessary; I'm using a three inch here.  They are available through www.leevalley.com priced fairly and easy to sharpen.

 

Lay out the same size screw as you used to secure the log onto the faceplate and make a mark.  Add ½" to part the finished piece off, ½" for the bottom recess,  ½" for the bottom thickness and ½" to play with.  This is the depth you will want to drill your hole to.  You may find a drill extenstion is necessary. 

 

 

Set up your boring bar including the secondary tool rest, floor stand and in this case my laser attachment.  Be sure everything is level and the cutter tip is at center; this procedure should be done prior to mounting a log on the spindle.

 

 

 

 

Do as I say, not as I do! Even though I am only wearing my safety glasses here, don your face shield, because the chips will be flying.  You'll be surprised at how quick and easy it is to remove large quantities if wood.  At this point I'll have my lathe speed at about 800 RPM; for narrower diameter vessels I'll increase the speed to about 1100 once everything is nicely trued up. Be mindful of the lathe vibration as you may have to adjust your speed accordingly. 

 

 

 

  

  

 

 

A little paraffin wax will go a long ways in reducing the friction of the 50 lb. bar sliding on the secondary tool rest.

 

 

While working your way down the interior, please note the hand position on the bar.  In particular, the left hand which is positioned directly over the rest with the thumb pressed against the side.  In theory, only the left hand is controlling the motion and very fine or aggressive cuts can be obtained with unbelievable control.  This fine control is particularly important when turning thin walled vessels as I normally do.

 

  

 

You've probably noticed the light near the cutter; this set up is primarily used when turning thin vessels where I use the light to gauge the wall thickness, rather than using calipers or the laser.  The light itself is a 12 volt automotive bulb and socket but in order to increase the intensity, I've hooked it up to an 18 - 24 volt transformer.  A 12 volt battery charger will replace the transformer quite nicely if you don't desire the extra intensity.  Light kits complete with switch, socket, transformer and wiring are available through both Gord's and my web sites.

 

At this point I've set the laser measuring system to ¾".  My system is homemade by a friend of mine who, unfortunately, doesn't market them, but there are a couple of other aftermarket systems available that can be used on the 1 ½" bar.  The two laser measuring systems that I would recommend and are quite compatible with our system are: www.lindsaylathetools.com or www.monsterlathetools.com The Lindsay LatheTools system is more heavy duty and can reach up to 48 inches.  The Monster Lathe Tool system has a capacity of about 20 inches. 

Note one red mark is a dot and the other is a line.  The dot means you still have considerable amount of wood to remove whereas the line indicates that you are getting very close to your desired thickness.  Once the line has completely disappeared off the vase then you are at exactly the ¾ inch I've pre-set.  I usually stop when the line is long thus giving me a little material to play with.

 

I don't use the laser to measure wall thickness when I'm turning thin walled vessels.  Most of my thin pieces are turned to 3/32" and I've found the laser isn't accurate enough to achieve this due to the vibration of the laser attachment.

 

 Working my way down the interior.

 

 
Be sure to finish the first half or so of the inside before you do the final shaping of the outside.  Remember you want the mass to prevent movement.  This isn't quite as important when turning thick, as in this case, but it's a good habit to get into.

 

At this point I would have about 80% of the interior finished; and would complete the outside including a foot if so desired.

 

 

Once you have the outside of the bottom formed, finish off the interior.  One huge mistake we can make at this point, whether we're turning thin or thick vessels, is leaving the bottom thicker than the rest.  It's important if you expect a green piece of timber to dry without checking, to have a consistent thickness.  I tend to turn the bottom a little thinner to help with the drying process.

While I'm on the subject of drying, I should touch on what steps I take to help prevent checking and cracking.  There is no guarantee your beautiful vase won't crack but there are steps I believe do help.  Thin walled vessels are much easier to dry and I lose very few of them; thick ones on the other hand can give me fits.  First of all as I mentioned, consistent thickness particularly on the bottom is vital; secondly I try to store the pieces in a coldish area to slow down the drying and I always place them in plastic bags for the first month or two, only removing them occasionally to release the moisture.  If it is convenient, try every day or two for a few hours.  This seems to work best for me.  If you leave them in plastic and forget about them, they may rot or stain, depending on the timber.

 

Before parting off the vase I'd pretty up the piece with the cabinet scraper as well as a little sandpaper.

These high speed steel teardrop cutters have a number of cutting surfaces that can be used to your advantage.  I generally use the tip for aggressive roughing and with a quick adjustment I rotate the cutter so a larger radius is making a nice finishing cut.  With a little practice you'll be able to achieve quite a smooth finish. Gord and I manufacture two different lengths of the cutters; the longer one is ideal for hard to reach areas if you are undercutting the opening.

 

  

 

 

 

Sharpening is a breeze and generally takes less than a minute including removing and reinstalling the cutter.  I've built a table on my grinder that allows me to work very close to the stone and stays set at the proper angle.  The cutters we sell are ground to the correct angle.

 

 

When parting off these thick walled vessels, it's important to secure the vase from the tail stock end because of their weight.  I've turned a couple of different lengths and shaped spigots that mount on a live center in the tail stock.  Just firm pressure is all that is needed.  I generally don't bother with this step with thin walled smaller vessels but again it is a good habit to get into and will ensure that you won't have a vase rolling around your shop. 

 

 

 

 

 

 

Using a pretty heavy duty parting tool, part down to about 1 inch or more if the vase starts wobbling uncomfortably.

 
   

 

 

 

With the lathe off at this point I use a pull saw to cut through the final 1 inch spigot.  I don't make the cut flush with the bottom of the vase as I want an easy reference to find center.  

 

 

 

 

 

 

 

I measure both the interior and exterior heights to determine my bottom thickness; just so I don't turn too thin when I turn a recess into the bottom.

 

 

 

 

 

 

 

 

Mark the center with an awl.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mount one of the spigots onto the spindle.  This design also works well for the parting off step we did a few minutes ago.  The spigot has to be of sufficient length to reach to the bottom of your vase.

  

 

 

 

 

Move the tailstock point into the marked center and firmly tighten the vase against the spigot.  The Oneway Live Centres or something similar with a center point and outer ring work great as they don't tend to keep sinking into the wood. 

It's very important to turn your lathe speed down at this point; for a piece this size about 300 RPM is comfortable.  If you are getting much wobble even slower would be a good idea.  Now's a good time to reshape the foot if you like and in this case I also want to remove little of the bottom thickness before I turn the recess.

 

I like to use a dovetail scraper to start my recess and create the dovetail that I'll use at a later date in order to re-chuck for decorating and sanding.  Then I finish off the recess with a ¼" bowl gouge turning down to a small tenon.  The size you can turn this tenon will be determined by the weight of your piece, how true it's running and the lathe speed.  I usually turn it to ½ inch or so but common sense is in order here.  I can honestly say I've never lost a piece using this method but remember to keep firm pressure between the spindle spigot and the tail stock.

A power chisel will make short work of the small piece that's left.  Any sharp chisel will do, I've even used a sharp skew when nothing else was available.

 

 

 

 

 

As I explained earlier, this is when the drying process begins and you must be patient.  Because it's turned end grain, there won't be a lot of warpage and they will generally stay quite round.  Once the vase is dry to my satisfaction I'll re-chuck it into the recess I created and gently sand both the inside and out.  Do not, under any circumstances,  try to sand the bottom of the inside with the lathe running and be very careful sanding the inside walls.  

 

 

 

 

 

 

 

 

 

 

 

This is a good example of what I like to create using these thick walled vessels.  It is relief carved using power carvers, textured with a woodburner, painted using acrylic paint and finished with spray lacquer.   

 

 

 

As hard as I try to give all of the details needed to create these deep hollow turnings, invariably I miss something.  A little practice will go a long way and until you get the hang of it, a lot of common sense figuring things out will be a great attribute.  Our DVD called Brian McEvoy's Secrets To Mastering The Large Captive Boring Bar will also help you out a great deal.

 

 
 
Another example of some of my latest works, created using the 1-1/2" Large Captive Boring Bar.  These natural edge vases were turned with dry Maple Burl and the largest piece measures 10" x 22".

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 
 

 

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