mounting green wood for end grain hollowing

[Stan Calow]

What's the best way to mount a green workpiece for end-grain hollowing? I've tried faceplates, but the screws (1" machine screws) always pop out with the slightest catch or the general imbalance at the start of turning. Videos and my reference books don't seem to address mounting, just the hollowing.
Thanks for any input.

[Steve Schlumpf]

I have always used a tenon and a steady rest once the form has been roughed out. What form are you planning on turning? Might make a difference as to how it is held.

[Richard Coers]

I start with turning between centers. With big work I use the OneWay Big Bite. Then go to a tenon and chuck. 1" screws are very short, especially if you are using a welded faceplate. Not sure what a machine screw for wood is, but I use stainless steel sheet metal screws.

[Stan Calow]

Richard thats the kind of screws I meant - sheet metal screws. One inch because that was a recommendation I read in a turning book, but not specifically for green wood. Steve, they're going to be some small bowls, maybe lidded boxes. Log is about 5.5" diam, so not much room for more. Once I get them roughed out and can turn a tenon, I know what to do, but its that initial roughing out part where I keep getting sudden failures. I assumed it was because the screws wont hold the wet end grain.

[Kevin Jenness]

Endgrain does not hold screws as well as side grain, so if using a faceplate longer screws are in order. I use the tailstock whenever possible for roughing. No reason not to turn between centers as Richard says.

[John K Jordan]

What's the best way to mount a green workpiece for end-grain hollowing? I've tried faceplates, but the screws (1" machine screws) always pop out with the slightest catch or the general imbalance at the start of turning. Videos and my reference books don't seem to address mounting, just the hollowing.
Thanks for any input.

What is the size of the work? Everyone I know uses a chuck for end grain work, in compression mode, meaning first turning a tenon. I (and I think most) do this by first mounting the wood between centers. Relatively small square blanks can be held directly in large enough jaws directly without turning a tenon but the grip is not as secure. Be careful to shape and size the tenon appropriately for the jaws.

For their Powergrip jaws Teknatool recommends a maximum blank size of 8" diameter x 12" length. The Titan chuck with the Titan Powergrip jaws is rated for up to 14" diameter and 14" length.

BTW, when tightening a chuck, especially one that has internal pinion gears, you can get a much better grip by repeatedly tightening in both of the chuck key sockets rather than just crank down in just one place. It's amazing how well this works. I heard a demonstrator once recommend "tighten the chuck in all six places." :)

JKJ

[Richard Coers]

Another tip is to bring up the tailstock during the roughing work.

[roger wiegand]

I always start between centers, both because it is safer and because I can re-orient the piece as the grain starts to be revealed. I do almost all the exterior shaping between centers. Then I put a tenon on it and hold it in a chuck for hollowing. I use a big chuck (Vicmarc 150) with the largest jaws that will close on the piece-- the tenon is generally considerably larger than the finished dimension of the foot of the piece, but it holds very securely. (Haven't knocked one off the chuck since acquiring a hollowing rig and TV camera system). I haven't done anything deeper than a foot or so, so haven't had need of a steady rest yet.

[Stan Calow]

Thanks everyone for input. I always do the roughing between centers, but have had trouble getting live centers to maintain a grip in green wood, thats why I was trying faceplates. I am only doing relatively small turnings on a midi lathe, so can go to a 4-jaw chuck when I get a tenon, just can't get past the roughing stage.

[Tom Wilson66]

I use a marcantel drive for initial roughing, then use a four jaw chuck. The review posted here will explain how these work. They work quite well, and I don't know why there isn't more mention of them on the forum. This would hold green wood quite well, and not need the extra length for long screws.

https://sawmillcreek.org/content.php?130-Review-Jerry-Marcantel%2592s-Chuck-Plate

Tom

[Kevin Jenness]

I am guessing you were not using the tailstock when the faceplate screws pulled out, correct? A faceplate will work with long enough screws but there's no reason not to use the tailstock as well before hollowing. A spur center does give more adjustability when deciding on the blank's orientation. It's easy to spin out a small spur center when roughing- the larger diameter the better. The Oneway Big Bite Richard Coers mentioned is one good option. I am considering an Elio drive. https://woodturningtoolstore.com/product/elio-dr-safe-drive-2-5/

[John K Jordan]

... I've tried faceplates, but the screws (1" machine screws) always pop out with the slightest catch or the general imbalance at the start of turning...


... they're going to be some small bowls, maybe lidded boxes. Log is about 5.5" diam, so not much room for more. Once I get them roughed out and can turn a tenon, I know what to do, but its that initial roughing out part where I keep getting sudden failures. ...


... I always do the roughing between centers, but have had trouble getting live centers to maintain a grip in green wood,.... I am only doing relatively small turnings on a midi lathe, so can go to a 4-jaw chuck when I get a tenon, just can't get past the roughing stage.


Stan,

What kind of wood?
What types of centers?
What tool(s) are you using?

It's difficult to know what to suggest without seeing you work. I hesitate to speculate on your tool technique but you really shouldn't be getting any significant catches. But if the piece is coming off the lathe due to imbalance that's a problem you should be able to fix.

--Some ideas...
If possible, make the blank as balanced as possible before mounting on the lathe. Some use a chainsaw to make the blank at least octagonal in shape before mounting. I generally use a bandsaw if it will handle the blank height (after squaring off the ends.) I like to lightly mount the wood between points of the centers and without turning on the lathe see how well it is balanced, adjusting the wood a little a time on one or both centers until it is balanced. Then tighten up the tailstock to mark the center points.

Squaring off the ends can help a lot with the holding.

If the wood is soft, driving a large spur center into the end with a hammer before mounting can provide better holding. If the end is not squared a spur drive center with just two spurs may be better than one with four, especially if the wood is hard. I always work with squared ends and prefer holding with steb drive and live centers. (I also almost always turn dry wood.)

--As for catches, some general points (not to be taken as criticism of your tools or technique since I haven't seen you work!):
Taking a big bite with a big tool can, of course, cause a big catch. A smaller diameter gouge can take a smaller bite. Smaller and more gentle cuts with a large gouge can work. The gouge, of course, should be razor sharp. (Using flat-topped carbide tools or scrapers to rough a blank can be a challenge.)

There should be very little side force put on the blank when roughing. Cutting directly into the side of a rough blank can cause large side forces. Making roughing cuts more-or-less parallel to the lathe axis can be very gentle. This is especially important when face turning but also for end grain pieces, generally avoiding cutting "up hill" relative to the grain direction.
I specifically do NOT recommend this idea if you are already having pieces come off the lathe but once that is solved: increasing the speed can make roughing smoother, assuming the blank is balanced. Not a safe technique with a large, heavy blank or one with cracks and voids!

Again, without knowing more about your technique and experience I'm just guessing. Just curious, do you have expertise with spindle turning?

It's difficult in this time of raging pandemic, but it might be very helpful to have another turner see your setup and watch you work. Even Facetime might work.


BTW, when I turn lidded boxes from green wood I turn a cylinder with tenons on both ends, mount one end in the chuck, part off somewhere to make the blank for the lid, partially hollow first the body then the lid (leaving the walls thick), then set both pieces aside until they are well dried before continuing. When dry, I turn the box "most" of the way then let it sit, at least over night before finish turning - this lets stresses in the wood release and makes it easier to get a perfect fit on the lid. This is a common technique - I learned it from Richard Raffan. A end-grain bowl or hollow form or face turned bowl from green wood, of course, can be done in one sitting.

JKJ

[Brian Deakin]

John Stated

BTW, when tightening a chuck, especially one that has internal pinion gears, you can get a much better grip by repeatedly tightening in both of the chuck key sockets rather than just crank down in just one place. It's amazing how well this works. I heard a demonstrator once recommend "tighten the chuck in all six places.

Stuart Batty advises a correct size tenon and a shoulder provide the best stability and to check the tightness of the grip of the jaws and retighten during the turning process Especially if you have broken off from turning example gone to lunch
Axminster tools who manufacturer chucks have a video which echoes John's statement

[Stan Calow]

Thanks guys. I know its hard to visualize. The problems I've had were when turning green sections of logs mounted on end, not typical cross grain bowl cuts. This has been in maple, ash, elm, redbud, and even basswood. These were sections about 6 inches long, 4-6" diameter. Its spindle turning, and I am just talking about during the roughing stage, trying to make smooth cylinders, (not even getting to the stage of cutting out the center. Turning on centers, the (Steb or 4-point) center to eventually start spinning a hole in the wet green end grain.Because the outside surface of the log is rough, there are tiny little catches (not blowouts) from the bark or surface irregularities, thus creating repeated small stresses on the contact points with the centers, eventually they spin free. I blamed this on the wetness of the end grain.

So I thought mounting the log sections on a faceplate would be sturdier, again just for the initial roughing turning (with a live center on the tailstock). Again, after a while of roughing a log into a cylinder, the screws pull out of the wet wood and the piece falls off, not the typical explosion of the workpiece. I've used faceplates on dry wood all the time, so I'm comfortable with that. So I am inferring the problem is with wet, green endgrain, and, other than longer screws, if there's a better way to mount a log section. If my lathe were bigger, I'd just get bigger jaws.

If its a technique issue, I'll accept that answer.

[roger wiegand]

Stan, with all respect, I think you have a different issue, unrelated to how you are holding the work. For pieces of log or quarters of tree trunks up to about 8" in diameter I use a drive like this one:
445071
in my headstock. No teeth, no screws, no spurs. For bigger work I have a screw-on adapter for it from robust that makes a ~35mm circle. I've driven rough logs over 20" in diameter with that. I will occasionally get a catch that stops the piece spinning, but that is rare (and one of the big advantages of this type of drive). I think you probably have an issue with either sharpness of tools or how you are presenting them to the work or both.

If at all possible I'd suggest you get together with an experienced mentor on Zoom or in person if conditions in your area make that sensible, to watch what you are doing and provide some coaching. You should not be routinely getting catches that would cause a spur center to slip or even 1" screws to pull out. Too heavy a cut, bad angle between the tool and wood, and dull tools can all contribute to that.

[Chris A Lawrence]

Turning on centers, the (Steb or 4-point) center to eventually start spinning a hole in the wet green end grain.

Steb centers are not good for this situation they are designed as a safety center to prevent bad catches. I will echo using a bigger 4 point center if you are using the stock one that came with the lathe. I use the Axminster jumbo drive center and have been able to rough turn 12+ inch diameter logs with out issues.

[Steve Schlumpf]

Stan, I use Jerry Marcantel's drive center on everything I rough out but basically all you are doing is using a jam chuck when spindle turning. If you have everything tight when roughing and it still breaks loose, makes me wonder if you are getting bad catches? Being spindle turning, did you raise the height of your tool rest so that you are cutting slightly above center? Other than that, only thing I can think of is amount of pressure you are applying is either too light to retain the work or so tight that it wants to split the wood. Any chance you can share some photos of your setup? That would help direct everyone's suggestions.

[Don Stephan]

Stan: Having just read your Sunday morning post, could you gently turn between centers enough to make a tenon at each end, then hold each end in turn in a four jaw chuck while you continue roughing out to a cylinder the half of the blank at the tailstock end? Given the experience, as has been suggested more than once I would use the tailstock while roughing out tghe cylinder, even with the four jaw chuck.

[Edward Weingarden]

Your description of your use of the face plate sounds like you are mounting it on the rough blank. If that is the case, there are a few issues to be aware of. The face plate needs to be mounted on a flat surface with a slight concave shape to it. That will ensure that the face plate has complete contact with the wood around the entire circumference of it. The next issue is that with a face plate mounted on a rough blank, you can't balance the blank prior to starting the roughing phase. Spinning a log that is out balance will put addition stress on the face plate/screws. The method I use is as follows:

I mount the blank between centers with a spur drive and live center (as others have mentioned), and balance the blank prior to turning. Once the blank has been turned into a cylinder I square the ends. Since I mount the face plate on what is currently the tail stock end, I make sure there is a slight concavity on that surface. Before removing the cylinder from the lathe, I make pencil marks on the end which will have the face plate mounted on it. I make the pencil marks as the lathe is spinning so that I get a number of circles, each with a slightly larger diameter than the preceding one. I use the circles to help center the face plate. I pre-drill the mounting holes so that the screws are not separating the end grain, but allow the threads to bite into the wood. I have also found that if I didn't pre-drill the mounting holes, it could be very difficult to get the screws out. The face plates I use are 1/4" in thickness; the screws I use are 1 1/4" - 1 1/2" long (depending on the size of the blank). Thus, I have at least 1" of screw in the wood for a smaller blank, and 1 1/4" for a larger blank. My face plates have at least 6 mounting holes (more for a larger plate) and a screw goes in each one of them. When the cylinder is remounted using the face plate and tail stock support, it will run slightly out of true until you make one or two passes to true-it up again. I have never had a blank separate from a face plate using this method.

With all that said, I also use a chuck to mount my hollow forms. I add a steady rest with the set-up if the hollow form is about 8" or deeper. Hope that helps.

[Stan Calow]

Edward, yes I was mounting rough blanks to a faceplate (on a flat end-grain face) with a live center in the tailstock. Just to get the outside rounded. With a tenon, I would go to put a four-jaw chuck if I get that far. I've done many small cross-grain turnings with no issue. Roger, I was under the impression that with a center like the one you show (a single point) you were likely to split a end grain mount since you're pushing into the grain. So I tried using a spur center or a cup center in the tailstock as well.

Next time I'll be trying this, I'll take some photos, but I got a good idea of how to proceed. And yes it never hurts to check the sharpness. Thanks everyone.

[roger wiegand]

That was just a picture I found on the interweb, in use the point is adjusted so it sticks out only 1/16-1/8"-- it's just there for centering on a specific spot. You don't need to use it at all. The ring around it is what does the work.




Edward, yes I was mounting rough blanks to a faceplate (on a flat end-grain face) with a live center in the tailstock. Just to get the outside rounded. With a tenon, I would go to put a four-jaw chuck if I get that far. I've done many small cross-grain turnings with no issue. Roger, I was under the impression that with a center like the one you show (a single point) you were likely to split a end grain mount since you're pushing into the grain. So I tried using a spur center or a cup center in the tailstock as well.

Next time I'll be trying this, I'll take some photos, but I got a good idea of how to proceed. And yes it never hurts to check the sharpness. Thanks everyone.

[Reed Gray]

Well, Lyle Jamieson likes bolts into end grain for his pieces. He uses over sized ones and goes in pretty deep. 1 inch screws won't work. If you use that method, I would suggest 'toe' nailing which means instead of going straight in parallel to the grain, you go in at an angle. It can be made to work. Oh, the part on the face plate needs to be dead flat. Other than that, like every one else does, between centers, turn a tenon, use a big chuck, and for big pieces, use a steady rest.

robo hippy

[Randy Heinemann]

Thanks everyone for input. I always do the roughing between centers, but have had trouble getting live centers to maintain a grip in green wood, thats why I was trying faceplates. I am only doing relatively small turnings on a midi lathe, so can go to a 4-jaw chuck when I get a tenon, just can't get past the roughing stage.

I have begun turning smaller hollow forms on my Nova Comet II; also a midi lathe. The lathe has sufficient power so no problem there. However, I noticed that the size tenon which the chuck allows isn't as large as a full-size lathe. This seems to make it more likely that the chuck will let go when hollowing given the amount of force involved with end-grain hollowing. I do tighten the chuck via both points on the chuck and usually do it at least twice in each. Then I give each a little extra turn periodically as I go through the hollowing process. The piece still ends up coming loose at least a couple of times during the hollowing process. It doesn't come off the lathe, but does loosen up so that I need to remount and retighten.

I think hollowing on a full-size lathe with a larger chuck would eliminate most of the problems I'm having. For now, though, I'm not in the market to upgrade. I suppose I could purchase a different chuck as there are likely others available that would fit and would allow a larger tenon.

I would be the first to admit that I'm new to hollowing as I've turned mostly bowls and this may become less of a problem as I develop my technique. Right now, my technique is a little rough and the results are also.

[Mike Nathal]

I have experienced the spur drive drilling into end grain problem. Never use a Steb center for this. A big reason for this is that the wood is so wet that it is moving too much and you need to continually tighten the tail stock to prevent the drilling. The drive that Roger W. referred to is called a safety center, it may well work, I never tried it on green wood. Continuously tightening the tail stock is the key with the safety drive also. Sometimes you can remove the blank, and clean up the hole you have drilled with a chisel to make it flat again. Sharpening the spurs also helps. As Don suggests, another good way to go is to get a tenon formed right away on the tail stock end, prior to truing up the rest of the blank. Then, if you start to get the spur drive drilling in, you can switch to the chuck. (Always with the tailstock)

[John King]

1-1/4" #12 pan head sheet metal screws with tailstock support while balancing and shaping exterior of piece. - John

[Stan Calow]

Lots of good guidance here. Thanks all. Its one of my long time complaints about guidebooks and videos leaving out a lot of the details or assume too much.

[robert baccus]

To reverse the piece use a glueblock and thick CA glue--it holds very well on wet wood.

[John K Jordan]

To reverse the piece use a glueblock and thick CA glue--it holds very well on wet wood.

Does this also hold well to end grain as the OP is using? I haven't tried that. I assume the end first needs to be flattened before gluing the waste block which might complicate the balancing step.

I have soaked soft wet end grain with fine CA to harden the wood give the drive center a little better bite.

[robert baccus]

Sure---sticks to wet or dry endgrain. used it for dozens of log section vase blanks to 125 #'s. Outside and hollowing (using a stabilizer wheel) and finishing as well. Use plenty of glue and a flat surface yeah. Screws and wood glues are horrible on wet endgrain---dents in my shop ceiling to remind me of the learning curve.