PDA

View Full Version : Hollow Forms and How I Turn Them



Steve Schlumpf
01-18-2008, 10:57 AM
The following information on hollow forms is being presented with the beginning turner in mind. It is the simple intent of this post to expose the beginner to the various steps involved in creating a hollow form.

The normal disclaimer: I am not an instructor and have learned what I know through active participation here on SawMill Creek and trial and error. These photos offer only a few of the many possible ways to turn hollow forms. Most importantly, my methods work for me… if something doesn’t look or ‘feel’ safe to you – DON’T do it!

List of tools:
Jet 1642 EVS 2 hp Lathe, 7 bags of concrete
Chainsaw
Talon Chuck and various jaws
6” Faceplate, came with the lathe
Homemade Steady Rest
½” Bowl Gouge
1/8” Parting Tool
Monster Captured Hollowing System with Laser
Cheapest electric drill I could find
2” sanding disks, various grits

I start with green (wet) wood and chainsaw the blank from a log using the procedure that Bill Grumbine demonstrates in his video “Bowl Turning Made Easy”. (this is an excellent video and I still study and learn from it!)

I use the chainsaw to ‘round’ the blank as much as I can so it is easier to rough out. You don’t have to cut the corners off the blank first but it makes everything faster and a lot easier on your body.


Roughing out the Hollow Form

Step 1: Here I have a large blank on the lathe. The blank is mounted using a 6” faceplate and some good steel sheet metal screws. The tailstock is brought up to support the blank. The first step is to shape what is going to be the bottom portion of the hollow form and also to form the tenon. I’ll showcase the tenon in another photo later. At this step I usually run my lathe around 200 to 400 rpm depending on how out of balance the blank is. The general idea is SLOW speed until you get the blank rounded. Also, when shaping the form the only tool I use is a ½” bowl gouge. It’s not the only way to shape the form, it’s just the tool I prefer.
79499

Step 2: Once step 1 is completed, remove the faceplate, reverse the blank and mount it in the chuck using the tenon. Bring the tailstock up seat into the blank. Now that the blank is somewhat more balanced I increase the speed a little which helps to remove stock faster and also gives a smoother cut.
79500

Step 3: This is where you form the face (top) of the hollow form. Figure out approximately how large the opening is going to be and adjust your design so that the face and opening flow together with a continuous curve.
79501

Step 4a: The outside of the form is now complete and I setup for hollowing. I remove the tailstock and install the steady rest. As you can see, it is a very simple design made out of scraps but it works very well! The wheels run on the largest diameter of the form and support it while hollowing. 4b shows the back side of the steady rest and another view of the way the piece is held in the chuck.
79502 79503

Steve Schlumpf
01-18-2008, 10:57 AM
Roughing Out continued…

Step 5: Rough out the inside of the form. I try to leave the walls at least 10% of the diameter of the form. This is usually more wood than necessary but it does allow for small design changes once you finish turn the piece.

Roughing out green wood is about as messy as it gets. You’ll have to stop often and remove wet shavings from the inside of the form but it is a great time to play with whatever tools you have for hollowing and figure out how each works. I found that the square bits work well for cutting and fast stock removal and the curved bits are for smoothing out the ridges the square bits left behind. Green wood is fairly forgiving so just play with each bit and see how it feels.

For me, the best rules for hollowing are: Make sure the cutting edge is on the centerline or below, use light cuts, sharp bits and smooth movements as much as possible. If you have to push – then chances are your bit is dull or you’re not close to the centerline. Couple of other things to remember is to keep the tool rest close to the work as this will help reduce vibration. Also try to keep the tool bit parallel to the bed of the lathe. If the bit is allowed to rotate down – the edge will not contact the wood and if the edge rotates up above the centerline you will have what is known as a catch and bad words will be said!! I should also mention that I use sweeping motions just like when turning the inside of a bowl. Start at the left and move towards the center of the work and headstock.

When hollowing, everything inside is cut strictly by feel. If you want to actually see how the hollowing tools work, then I suggest a practice session using a green bowl blank. It might give you a better understanding of what’s happening when you are hollowing.
79504

Step 6: Remove the blank from lathe and DNA soak. I use the DNA method that Dave Smith developed and found that Dennis Peacock has an excellent tutorial already on SawMill that covers the DNA process and he included photos! Check it out here http://www.sawmillcreek.org/showthread.php?t=34370
79505

Step 7: After DNA I let the blank dry for 20 minutes or so and then write the date on the tenon with a gel pen. Wrap the form in brown paper bag and leave an opening over the entry hole so the hollow form can breathe. I also date the outside of the brown paper bag and place up-side-down on a rack to dry. Depending on where you live the blank may be ready to turn in just a few weeks. I usually let mine dry for a couple of months and then start finish turning.

Steve Schlumpf
01-18-2008, 10:58 AM
Finish Turning a Hollow Form

Step 1: Mount the roughed out hollow form using the Talon chuck with whatever jaws fit the opening. I also bring up the tailstock and, using the original tailstock divot, center and secure the hollow form.
79506

Step 2: The blank will have warped during the drying process – so the first priority is to true up the tenon and it’s shoulder area. This is an important step because not only does the grip on the tenon hold the work in place, it also determines the centerline for the form! I use a bowl gouge to true the tenon and my parting tool to clean the shoulder area.

Hint: Make sure the tenon and shoulder are perpendicular to each other and the length of the tenon will not bottom out in your chuck! Please note that I use a Talon chuck and true everything up accordingly. The chuck you have may require a different tenon profile but the concept is the same!

After the tenon is formed I then go on to shape what will become the outside bottom of the hollow form. This is where having a little additional wood left over from the roughing out process allows you to make small changes in the profile.

A lot of folks get concerned about RPMs or speed of their lathe during all these steps. There are charts out there with recommended speeds for a given size of turning. I turn at whatever speed I’m comfortable with at the time but remember the general rule “the bigger the item, the slower the speed.” I turn the outsides of the form around 400 rpm while it is warped and from 550 to 700 once it is trued.

After finishing with the shape I sand the form. This is where you will notice tear out, ridges, dips, etc. I turn the lathe down slow and use the cheapest electric drill I could find and 2” sanding disks. I work through the grits starting with 80, 120 or 180 (depending on tool control) and ending with 320.
79507 79508

Step 3: Next step is to shape the face of the form. Mount the blank into the chuck. I push and rotate the blank towards the headstock with my right hand while at the same time visually making sure the tenon is fully seated and tighten the chuck with the left hand. To check that the blank is centered correctly just give the piece a small spin and confirm the area you just turned is running true. If not, loosen, rotate the blank slightly and try again. There are times when I use the tailstock to support the form while shaping the face, usually when the piece is very large or has a number of cracks that I’m keeping an eye on. In the case of this photo, I did not use the tailstock but I highly recommend using it whenever possible!

Because the face of the form is warped, I start turning around 400 rpm and then increase to 650 - 700 once the face is trued. I use a variety of pulling cuts as shown in Bill Grumbine’s video, starting close to center and pulling towards me. I find with practice you can cut an extremely nice surface and that gets rid of a lot of sanding!

Once you have the face shaped the way you want, it’s time to sand. Before you sand – make sure you have the final shape that you want. Take a step back and look at the form from a number of different angles – this is your last chance to change anything before you start hollowing!
79509 79510

Steve Schlumpf
01-18-2008, 10:58 AM
Finish Turning continued…

Step 4: At this point I set up the steady rest and captured hollowing system. Again, the steady rest rides on the largest diameter of the form and provides support.

Remember the warped wood I spoke of when I first started finishing the roughed out form? Well, it’s warped on the inside as well and that makes for some real bumpy – grabby cuts. Using very light cuts and working in small sections helps. It was because of the torque that develops inside the form and unexpected grabs and catches that I decided to move up to a captured system. The support frame that holds the d-handle removes most of the fight involved in cutting through the warped area inside a form.

Hollowing at this point is just a matter of working through the bits. I use the square bits to cut the walls to get close to whatever thickness I want for the form. I would love to be able to turn hollow forms with a 1/8” consistent thickness but I’m not there yet. To get to ¼” thickness I cut the walls down to about 5/16” to 3/8” and then switch over to a curved bit and smooth out the walls.

A note about the square bits… when the bit is sharp it is very easy to get aggressive with your cuts and that usually results in tear out or a sudden groove. While it takes a while longer to complete the hollowing if you take light cuts, you’ll save time by not reworking an area to remove the damage.

79511 79512 79513 79514

Steve Schlumpf
01-18-2008, 10:59 AM
Finish Turning continued…

Step 5: With hollowing complete the next thing to do is remove the tenon. While there are a number of ways to accomplish this, I use a homemade donut chuck. Very simple to make and they work great on most pieces. I bring up the tailstock to hold the piece in place while tightening the bolts. With the piece mounted in the donut chuck I make sure the form is running true by backing off the tailstock and giving the chuck a little spin. The tenon should run with minimal wobble – if not, you’ll notice that the divot was pulled to one side when compared to the tailstock center. Tighten the bolt on the opposite side of the direction of the pull and it should pull the center of the piece back into alignment.

With the lathe running around 500 RPM, I use the bowl gouge and very light cuts to remove the tenon. I like a slight concave foot which allows the form to sit without wobbling and doesn’t subtract from the profile of the piece.

Sand the foot area and remove the form from the donut chuck.
79515 79516 79517 79518

Step 6: For all purposes the hollow form is complete. Sign and date the bottom of the piece – it’s ready for whatever kind of finish you wish to apply.
79519

Remember, there are many different ways to achieve the same results. The steps I’ve listed here are simply what I do at this time. As we are all learning, please feel free to ask questions, offer suggestions or comment.

Tim Malyszko
01-18-2008, 11:25 AM
What an awesome demonstration. Thanks for posting this. I really like your steady rest and may replicate your design. I have some extra T-track laying around so this would be a perfect application for it.

Thanks so much for posting.

Jim Underwood
01-18-2008, 11:27 AM
Wow! Impressive Steve. Thanks for doing all that work and posting it for us.

You should volunteer to write articles for your club's newsletter.

Mark Patoka
01-18-2008, 11:43 AM
Excellent tutorial Steve. I've been admiring the work you post and have been wanted to starting turning some HFs myself. I'll definitely use some of your techniques. Keep up the sharing and the great work.

Bill Wyko
01-18-2008, 12:02 PM
Thanks Steve. I have a few chunks of wood that I'll be using your tutorial to work on. Very well done. Thanks again.

Mike Vickery
01-18-2008, 12:02 PM
Very nice tutorial Steve. I just stated changeing over from bowls to hollow forms and am sure this will be very helpfull.

Dana Berenson
01-18-2008, 12:06 PM
Steve, This is so informative and helpful to those of us who have not done something like this before. Thanks so much for sharing, what many people would charge $49.95 for. I REALLy like the work you have posted on this forum. You are quite the artist!

Thanks!

Brad Hammond
01-18-2008, 12:07 PM
posts like that are what sawmill is all about! excellent education! thanx so much for your time.

Tony De Masi
01-18-2008, 12:31 PM
Excellent job Steve. Thank you for the time and effort you put into this tutorial.

Tony

Ron Erickson
01-18-2008, 12:35 PM
Steve thanks for taking the time to post this, very informative.

Chris Fierro
01-18-2008, 12:40 PM
Thanks for posting the tutorial!

Ted Calver
01-18-2008, 12:49 PM
Steve,
Much appreciated!!

Hilel Salomon
01-18-2008, 12:50 PM
Super!!! Just plain Super!! Thanks, Hilel

Dick Latshaw
01-18-2008, 1:16 PM
Absolutely a great job Steve. Thanks for taking the time to put this together.:):):)

Mike Golka
01-18-2008, 1:20 PM
Great tutorial Steve, awsome job on the preentation.

Mike

David Duke
01-18-2008, 1:50 PM
posts like that are what sawmill is all about! excellent education! thanx so much for your time.

Couldn't of said it better myself :D:D:D .

Thanks Steve.........and I'm not even a spinny guy :eek: .

Mike Peace
01-18-2008, 1:51 PM
Thanks for taking the time to post your tutorial. The timing is excellent as I am ready to try a HF.

Tom Sherman
01-18-2008, 1:56 PM
You've done a nice job on the tutorial as well as the HF Steve. Way to go.Thanks for your time and effort.

Benjamin Dahl
01-18-2008, 2:02 PM
Steve, thanks for the information. makes it look a little less daunting.
Ben

steven carter
01-18-2008, 2:16 PM
Fantastic tutorial Steve - We appreciate your hard work setting this up.

Robert McGowen
01-18-2008, 2:23 PM
That should help a bunch of people Steve. Thank you for taking the time to do it.

Arlan Ten Kley
01-18-2008, 2:28 PM
Fabulous tutorial Steve! That's what I want to do when my lathe grows up!

michael gallagher
01-18-2008, 2:57 PM
Thanks for posting this...this wil help out the uninitiated in hollow form turning (e.g., me). I appreciate the time and effort you put into composing this tutorial.

Jason Clark2
01-18-2008, 3:02 PM
Great tutorial Steve, Do you have a preference of using the faceplate rather than a woodworm screw or starting off between centers? It seems like you're either losing a fair amount of wood off the top of the blank by the time you get down far enough to remove the screw holes or you're forced to use an opening larger than the diameter of the screw holes.

Thanks
Jason

Steve Schlumpf
01-18-2008, 3:10 PM
Thanks everyone for all the kind comments! I was hoping this would show that hollow forms are easy to turn and just require a few extra steps - no big deal!

Jason - I use the faceplate only on very large blanks and use the inner circle of holes for the screws. That way I know the blank is securely mounted and the holes it creates in the blank are located within the region I plan to remove anyway. Most of the time - hollow forms or bowls - I use the woodworm screw.

Bernie Weishapl
01-18-2008, 3:23 PM
Great tutorial Steve. Thanks for sharing.

Randy Privett
01-18-2008, 4:14 PM
Very Nice!

Randy

Jim Becker
01-18-2008, 4:25 PM
Very nice job on your pictorial, Steve!

Brian McInturff
01-18-2008, 5:05 PM
Well done Steve. You laid out the tutorial very well. I think I do mine pretty much the same way. I do like your donut chuck. I've been using my vacuum chuck and a tailstock adaptor(screw the chuck onto it while it's in the tailstock) to keep everything aligned. I think your tutorial should go down into the articles section or at least be a "sticky" here in the turners section.;)

Brian Weick
01-18-2008, 5:33 PM
that was a great presentation you gave- very well done and informative- I think that is very thoughtful of you to take the time to put this all together for those of us that don't do HF's and share your knowledge with us. It is people such as yourself that make this forum what is has become today- thank you very much for giving your personal presentation Steve ~ great touch!
Brain :)

Steve Campbell
01-18-2008, 6:57 PM
Thank you for going to all the work to help all us newbies. You may have just talked me into trying one.

Steve

robert hainstock
01-18-2008, 7:16 PM
Thanks neighbor. :D:D:D:D:D:D
Bob

BILL DONAHUE
01-18-2008, 7:24 PM
Nice job and it couldn't come at a better time. Just got a Mini Monster Hollowing System and will try my 1st one this weekend (after attending a demo by Alan Lacer in Pensacola). Questions - in what order are the tools used? There is one piece of metal included in the system that is 2"x 3/4"x3/4" with a 3/8" hole through it and a set screw in the side - what's it for? Thanks.

Steve Schlumpf
01-18-2008, 8:29 PM
Thanks again everyone for your kind comments! I am really glad that so many of you have found something helpful in the tutorial!

Bill - not really sure (without a pic) which piece of metal you are taking about. If I had to take a guess - the metal would have a 3/8" opening that is actually at an a 45* angle with respect to the support shaft. It is designed to hold whatever cutting bit you want and get up under the shoulder/collar area of the hollow form. If you can include a photo I would be more than happy to assist in figuring out how to use it - or - PM Randy and he will let you know the purpose of the tool in question.

Harold Tinling
01-18-2008, 9:20 PM
Great article! I'm curious as to what is the DNA soup? Thanks Harold

Ron Erickson
01-19-2008, 8:21 AM
Great article! I'm curious as to what is the DNA soup? Thanks Harold
Harold, DNA stands for De-Natured Alcohol.

Ron Drew
01-19-2008, 9:58 AM
That was just great Steve! Very detailed, and must have been quite time consuming. Thanks so much for sharing that with us. Ron

Burt Alcantara
01-19-2008, 10:45 AM
Steve,
Great tutorial and couldn't have been better timing. I sent my check to Randy for the Articulated Arm. I will use your tutorial to help me get started.

Thanks again for a wonderful job!
Burt

Ben Gastfriend
01-19-2008, 11:08 AM
Moderators:

I would definitley reccomend this article for the articles forum, and I'm sure others would support me.

Steve, great job! You do some awesome work and this pictorial is great, very informative! Thanks!

Bill Bolen
01-19-2008, 11:25 AM
Steve: I think this was the most concise and informative tutorial on HF's that I have seem. I picked up some nice tips that should help me doing HF's without going through the side.Thanks for all the time and effort you put in. It paid off well!...Bill...

David Wilhelm
01-19-2008, 12:42 PM
Great job Steve. This is a fine example of the worth in being a contributor. Keep up the good work!!!!!

Ron McKinley
01-19-2008, 3:06 PM
Great one Steve! I especially like your steadyrest......Ron

Ron Hipp
01-19-2008, 5:20 PM
Great pictures, tutorial and presentation....Thanks

Ron

michael gallagher
01-19-2008, 9:22 PM
I, for one, liked this tutorial. I also wanted it in one convenient file so I could study it, print it out, and when I feel experienced enough to give it a shot to have a copy sitting next to me by the lathe for the inevitable question of "how did he do that again?"

If you'd like it in one complete file with pictures, here it is:

http://www.billybobcpu.com/hollow.htm

EDDIE GLAZE
01-19-2008, 10:59 PM
Thanks Steve, Like Your Steady Rest. Happy Turning

Dale Gregory
01-20-2008, 9:18 AM
Steve, great post, and tutorial. Do you feel the steadyrest is a "must use" tool for HF's?

Dale

Ken Fitzgerald
01-20-2008, 9:40 AM
Very nicely done Steve!

Steve Schlumpf
01-20-2008, 9:42 AM
Thanks everyone for all the interest and kind comments - it is appreciated!

Dale - in a word - Yes! The blank is secured by the chuck only and without the steadyrest for support I honestly believe it would pose a flight risk. There are a lot of rotational forces that you encounter when hollowing (remember you can't see what's going on inside) and you need a way to help 'steady' or secure the form.

Michael Frazier
02-25-2008, 10:22 PM
Thanks so much
I am just getting started in hollow forms

Hilel Salomon
03-11-2008, 7:37 AM
Hi steve,

I'm late coming to this, but it was excellent. Everything you do on this forum personifies the best of Sawmill Creek. Your pictorial of the vacuum chuck setup was great, your answers to many of the questions posted here are truly a sign of generosity matching your artistry. Thanks, Hilel.

Christopher Fletcher
08-24-2008, 2:25 AM
Great tutorial! I love the donut chuck. As a new turner, my designs have been limited by my chuck jaw sizes. I generally let the wood dictate the shape, design, and size of the end project and I often feel that certain designs would be better served with no tenon or recess. So thanks for that unexpected suggestion. I really like the steady rest as well. I think I'll have to build something similar in the near future. As a side question, how much was the hollowing system that you used?

Don Shelton
11-05-2009, 8:30 AM
Thank you for sharing your methods and techniques. Excellent job with the illustrations and outlining the steps to create a beautiful hollow form.