Hollow vessels: What's yr hollowing sequence?

[Prashun Patel]

I'm a hollow form neophyte and I believe I must be doing something wrong. I have a Monster Articulating Arm Hollower, which makes it possible for even the ham handed to get it done, but it just doesn't feel right.

I'm coming from the bowl world, where most hollowing cuts are taken from the lip down to the bottom. In an HF, I can't figure out if it's better to start from the largest inner diameter and work down to the bottom and up to the lip in separate passes, or to make one sweep from the lip down.

I guess what I'm looking for is some kind of sequence of steps for hollowing (I'm doing side grain vessels at the moment).

I have no prob boring the initial hole and using a straight, square borer to get the general shape widened. It's the undercuts that seem too chattery. I get a lot of dust - instead of curlies. The dust seems hot and is a pain to scoop out of a small opening. Just doesn't feel efficient.

[Michael E. Thompson]

Prashun,

IMO you should always take the rim to thickness before going deeper. The problem is vibration. There won't be enough support on the bottom of the vessel to cut the top. Same concept as a bowl. Typically I will drill a hole to depth and hollow a good portion of the inside (leaving it thick for support). This will also make room for the cutter to maneuver inside the vessel. Finish to size the rim and work your way down. DON'T go back to the top once you finish.

The chatter may be due to not enough wood at the bottom of the form. Also make sure your tools are sharp, that could be why you are getting dust instead of curls. You will get mostly dust when turning end grain, side grain will create more of a curl. Look at how the tool is coming into the wood, are you too high or low to the center line?

When I turn the outside, I will only shape the top 1/2 or 2/3 of the form. Leaving a lot of mass to help support the wood. For this reason I don't typically use a steady rest. Once the top half is close to being hollowed to final size I will shape the rest of the form. It is surprising how much stability you get when going this route. I don't use the monster hollower (made my own version of the Jamieson) but these techniques should still work fine.

I realize this is a bit of a broken description, hope it helps.

Mike

[Jim Burr]

Just like some bowls Prashun, light cuts are in order. Heat does build up, so make sure you have a sharp cutter with a good burr on top. Remembering Mike Mahoneys' DVD on bowls was helpful in in HF's too! I usually set my depth with a drill bit then start from the top, work to the center and keep moving down. Center mass is important due to the stress on the thin walls of a HF. Make sure your cutter lip is at centerline and watch your depth! There are many ways to reach your goal...these are just some suggestions that helped me.

[John Keeton]

Prashun, I sharpen my cutters frequently, and I use the 3/16" almost exclusively with it sharpened to a fairly acute nose. For clean up cuts, I do switch to a more rounded cutter, and also use some scraper cutters at a shear angle.

It sounds like you might be getting some vibration from lack of a steady. On more horizontal forms under 5", or so, I don't need a steady, but taller than that I find the steady really helps. In addition, if you have not left a large enough base to support the stresses of hollowing the mouth area, that will create vibration. You can take down the base after getting the inside removed from the top half of the form. I found this diagram online, and it may help some.

[Kyle Iwamoto]

Thanks! Im just starting to try my first "real" HF. I tried a couple real small ones with no success. That drawing helps a LOT.

[Reed Gray]

For starters, you can try end grain boxes. Instead of making them just cylinders, make them more like ginger jars, or small rounded on both inside and outside, jars. You can see what is going on on the inside. The other thing to learn is cutting with the grain. Back to pencil sharpening with your pocket knife, cut down through the grain. For getting the chips out, an air hose works great. You can use some plastic tubing (funny pipe to landscapers) and blow it out, but remember to inhale before you put the pipe inside the form. Do not take the form out of your chuck as it never goes back on the same way. You can unscrew the chuck and dump the shavings out as well. If you want to look inside and see, the mag lights which can focus the beam work best.

robo hippy

[Wally Dickerman]

Prashum. if I can get your email address I'll send you a 2-page handout I give to my students in a beginning hollowform class.

Couple of tips...Start your HF turning by turning wide mouth HF's. Narrow openings can come later....When hollowing, measure wall thickness frequently. An experienced turner listens to the sound of the wood being cut. Most of us are familiar with the sound we hear just before cutting through the side of a vessel.

You haven't said what kind of hollowing tool you're using. I suggest that you practice on an open bowl so that you can become familiar with cutting action of the tool

[Prashun Patel]

Thank you everyone!
John that pic tells a lot. I had not considering doing the top 1/2 then the bottom.

Wally, I'm using the Monster Articulated Hollower. I did start with larger mouth HF's - everything from vases to 'enclosed' bowls. I have learned (am learning) to read the sound.

[Roger Chandler]

Okay, John has given you two really great tips here............the diagram.........his sequence is very similar to the one which David Ellsworth taught me...........the second is his mention of a good steady rest..........this will cut down considerably on chatter, and the other thing..........sharpen FREQUENTLY! Sometimes I sharpen about every 5 minutes of hollowing and most hf turners do not evacuate the chips often enough..........this is crucial to the process........sometimes it seems as if blowing out/vacuuming out the chips is all you do, but it really helps in getting the results you want!

[Jon Nuckles]

Prashun, I would add one thing I learned from a post on the Creek: make sure the the joints on the monster are snugged up. I had a terrible time using mine until I saw that post and tightened them up. It made a world of difference for me in avoiding vibration and catches.

[James Combs]

Prashun, I would add one thing I learned from a post on the Creek: make sure the the joints on the monster are snugged up. I had a terrible time using mine until I saw that post and tightened them up. It made a world of difference for me in avoiding vibration and catches.

+1 on making sure there is no play in the monster rig. BUT a word of caution especially if you have the smaller Mini Monster version. I don't know what kind of bearings the full size Monster has but I managed to over tighten mine putting ruts in the bearing races requiring replacement of the bearings.

[Prashun Patel]

Thanks, All. A couple nuggets really helped me:

1) The joints were NOT snugged. I didn't even see that one of the bolts had worked its way fairly loose.
2) I vaccuumed out the dust. Scooping just didn't get it all. I think I was experiencing chatter against that stuff.

It now cuts very well (getting the cutter in the hole not withstanding). However, during this process I learned a lot from you guys about the proper way to hollow. I'll work in sections from now on from the top down.

[John Keeton]

Prashun, on getting the cutter in the hole, I often set my laser, remove the cutter and insert it in the form and then reconnect it to the boring bar. Seems much more efficient that trying to maneuver the cutter in and take a chance on scarring the opening or getting the cutter in a bind and cracking the form.

Glad your hollowing experience is improving!

[Jim Underwood]

My hollowing sequence?

1) First mount between centers and get the outside shape.
2) Make a tenon on one end.
3 Mount the tenon in the chuck.
4) Bore a hole with a drill. Drill wanders offcenter. Start of fussing...
5) Begin with hollowing with straight manual hollowing tool. Start of getting beat up...
6) Get hollowed a ways, and notice you get little grabs from where the hole is no longer centered.
8) Hollow around the neck area with the goose neck tool, and get catches and make the hole bigger than you want. More fussing.
9) Finally get down a ways and really start getting the material out. Now we're talking... More getting beat up.
10) Then I notice I can't the nubbin out of the bottom from where the drill wandered off center... Fussing and maybe some bad words.
11) Now I"m really getting a good cut toward the bottom. Feels so good..
12) I cut through the side.

13) Some really bad words.
14) Throwing things.

15) Go back to turning tops.

[Prashun Patel]

I guess I'm already there, then, Jim. I resemble those remarks...

[Baxter Smith]

Had to smile at that one Jim! Sometimes I prefer to just cut to the chase. You can save a lot of extra fussing by simply cutting through the shoulder before having to mess with the bottom.

[Rick Markham]

Prashun, I only have a couple things to add. If you are turning wet wood, you need to clear the chips frequently, if they compact they can break your piece. Depending on the shape of you cutter, angle (etc.) you can use either pull or push cuts, or combinations of both. I generally make my bulk material removal material in back and forth movements, then a push or pull finishing cut (depending on which way the cutter cuts the cleanest.) Now this is a trick to it all, you are doing little bits of both the whole time, you will hog out material ahead of you to clear room for the cutter, head, and chips. Then take finishing cuts for a half inch or so down the form blending that one with the one above it. Hog out more material ahead of the cutter head, finishing cut etc. So keeping your cutter heads sharp is important. I generally resharpen when the first thing I am doing is taking the finishing cut/blending part first with a sharp cutter. (If that makes any sense) rinse and repeat, over and over. Wally is right too, your form will create a harmonic when it gets thin, My amphoras sing to me, and that's when I know I need to back off a bit (especially if you're taking a finishing cut.)

I use the maglight flashlight trick, if you shine the beam straight down to the bottom the shadows on the wall will reveal troughs and valleys. One of the things that helps me, is to turn the lathe off, clear the chips, reinsert the cutter head into the form and feel around for the ridge it has created ahead of it (lathe still off) If it's in a tricky region, I will practice my movements, I do this before finishing cuts generally, now when I actually make the cut I have some built up confidence, knowing the shape by feel.

Don't be afraid to put WD 40 on your toolrest and boring bar, it makes all of these things WAY easier when the bar isn't grabbing on the toolrest. :D Have fun!

[Tim Rinehart]

I use the maglight flashlight trick, if you shine the beam straight down to the bottom the shadows on the wall will reveal troughs and valleys. One of the things that helps me, is to turn the lathe off, clear the chips, reinsert the cutter head into the form and feel around for the ridge it has created ahead of it (lathe still off) If it's in a tricky region, I will practice my movements, I do this before finishing cuts generally, now when I actually make the cut I have some built up confidence, knowing the shape by feel.

Don't be afraid to put WD 40 on your toolrest and boring bar, it makes all of these things WAY easier when the bar isn't grabbing on the toolrest. :D Have fun!

Excellent points to bring up Rick!

I can't begin to express how much easier and predictable my Jamieson style rig got when I started waxing (paste wax) the sliding components before starting and then again during the process if anything started to hangup. The movement of your articulating arms should be similarly fluid, and perhaps a squirt or two of WD in the joints occasionally will help that, along with cleanup of any even minor nicks on your tool rest. If your joints come apart easily, perhaps some Teflon lubricant or paste wax would be a good option. YMMV on what works best for you, but anything better than nothing.

If you have access to a Harbor Freight, they have a nice light for looking inside when a maglight is too big... check out their item#95414...indispensable to me after you start using them.

Definitely doesn't sound like you're having fun with it yet...but you'll get there soon enough, you sound determined by asking alot of questions. When it clicks...you'll likely enjoy the hollowing nearly as much as forming the outside.

Good luck and enjoy!:D

[Prashun Patel]

Amazing tricks. Will try them. THANKS.

[Jim Underwood]

Which one; the drilling off center, or the nubbin in the bottom, or the cutting through the side? :D

[Tony Pridmore]

Which one; the drilling off center, or the nubbin in the bottom, or the cutting through the side? :D

From experience with all three, I can say that cutting through the side is the most effective. However, Prashun, you should try them all and form your own opinion.

[Thom Sturgill]

I recently sat through an all day session with David Ellsworth demoing and then a day's hand on training. I like his progression and have had success with it.
1) hollow in with the straight bar just past the depth of the widest part of the form. This hole should be straight sided and the diameter of the opening.
2) start opening up the hole with the straight bar under the sholder (about half way back in the hole) until you get to a point where the bar can't cut wide enough
3) shift to the bent bar(s) and continue removing material until you have the top to thickness and cleanly cut. Dress the opening at this time and sand the inside.
4) shift back to the straight bar and open the bottom portion of the original bore from step 1.
5) when you get to the point that the straaight bar no longer works shift back to the bent bar. and remove most of the material, leaving the wall a little thick.
6) clean up the wall section by section until you get to the bottom of the original cut. You now have the top half of the form finished.
7) bore the center to the final depth
8) open it up with the straight bar
9) finish with the bent tool except the very bottom

Be sure to remove cuttings and check yourself constantly. Deeper forms may need to be broken into more than three layers. John Jordan teaches a similar pattern. Get either DVD.