a little advice needed

[ahoiberg]

howdy all...

so i finally got some of my cherry stock cut up and i got a nice bowl blank, about 5-6 inches in diameter mounted to my lathe.

my first attempt at a bowl was a pretty small piece of juniper that ended when my tool met a nasty knot and the thing went flying across the room.

a few questions if you'll entertain them.

1) is it kosher to do the initial shaping of the outside of the bowl when it's just mounted with the drive center and tailstock for support? or should i initially turn a tenon and mount it with my chuck and tailstock for support?

2) what speed do you recommend for a guy who hasn't much experience in the bowl turning department? is faster easier for the cuts? FYI, i'll be doing most of the work with my bowl gouge as I don't have any "hollowing" tools per se.

i hope to start turning it tonight!

thanks y'all.

 

[Jurriaan]

1) use the tailstock as long as possible - more stable = better

2) I usually turn down the speed with my VFD until the lathe doesn't shake. Also, if your gouge gets hot from just rubbing the bevel, the speed is a little high . Other than that, anything goes IMVHO

 

[Ruth Niles]

Andrew wrote: "1) is it kosher to do the initial shaping of the outside of the bowl when it's just mounted with the drive center and tailstock for support? or should i initially turn a tenon and mount it with my chuck and tailstock for support?

2) what speed do you recommend for a guy who hasn't much experience in the bowl turning department? is faster easier for the cuts? FYI, i'll be doing most of the work with my bowl gouge as I don't have any "hollowing" tools per se. "
--------------------------------

Hi Andrew,

I turn the shape while it's mounted between centers using the tailstock. You may want to refine it once you have it in the jaw chuck.

Speed depends on type of wood, size of bowl and your comfort zone. Start at a medium speed, turn it up and judge for yourself if it's easier to cut. I use any speed that I'm comfortable and the tool is cutting nicely.

The bowl gouge is great for doing the whole bowl. I call myself a "lazy" turner because once I have a tool in my hand, I make it do all the cuts possible so I don't have to stop and pick up another one.

Have fun

Ruth

 

[Brodie Brickey]

Andrew,

You can shape the outside of the bowl between centers if you'd like. I'd recommend drilling a 1/2" deep hole where you put your spur drive (wide enough for the spur drive to fit in it). This will lessen the possibility of the piece "flying off".

If you aren't comfortable with the between centers, you can also mount a faceplate on the piece and turn the outside and the tenon. You can always, and should if the opportunity presents itself, bring the tailstock up to make you feel safer.

Roughing bowl speeds depend on how big the bowl is. If the blank is out of round you may need to slow it even further down or whip out the handsaw and balance the piece. Generally your slowest speeds are where you start shaping the bowl. Remember to use a bowl gouge for this, not a roughing gouge as they are designed to hold up to the side grain force with smaller tang in the handle.

As the piece becomes rounder you can speed up. There are times when you should speed up to keep you from taking bigger cuts by mistake. This comes into play if you are turning something with a voids. When you move the gouge into the wood, do so slowly to keep from ending up with half a gouge in a void and getting a big catch. In this kind of circumstance it can be beneficial to speed up the rotation so that the possibility of putting the gouge too far into a void is lessened.

Slower speeds don't give you as clean a cut generally. Since you're roughing this isn't a problem.

 

[David Somers]

Andrew,

There are a number of ways to do the initial turning and shaping of the outside. But as a rule of thumb, most folks like to begin with either a drive center or a faceplate on the headstock side, and the tailstock brought up for added support. My preference is for a faceplate since that holds better than a drive center. Both work fine though. The difference? A drive center will likely spin in the wood if you put too much pressure on the cut where a faceplate will not. As a new bowl turner the drive center might be a good protection for the belt on your lathe since if you work too agressively you will just end up turning the drive center into a drill rather than causing your motor and drive belt to slip.

So....for most techniques, the drive center or faceplate will be attached where the opening of the bowl will be, and the bottom of the bowl will be at the tailstock. While in this postion you will shape the outside of the bowl, as well as the tenon at the bottom of the bowl.

Since it sounds like this is your first bowl, try this for practice as you go. Shape the bowl a bit with roughing cuts. Then try some finishing cuts and see if you can get a pretty smooth finish. Then do another couple of rough cuts and get the shape closer to what you want. Do some more finishing cuts. Keep popping back and forth as you go. That way you get some extra time working on your finishing techniques while you have TONS of wood to play with. If you wait till the piece is shaped just the way you want it you will not have much room for error on your finishing cuts and you may be tempted to spend tons of time sanding instead out of fear. Just a thought.

A good habit to develop as you turn the outside is to spend most of your time watching the profile of the bowl at the top, not where your tool is cutting. This is unnerving for a new turner but it helps you relax your muscles, and it also helps you see the shape you are creating. If you are staring at the tool tip you can't see the shape and you tend to crouch a bit which is hard on your neck and shoulders. It takes some practice by the way. Think of this along the lines of the advice you got in drivers ed. Look well ahead of the front of your car. Look where you are going, not where you are. If you look where you are you can't anticipate what is coming at you and you tend to drive very tensely. Same idea in turning. Look at the profile at the top of the bowl, not the tool tip.

Next you would remove the bowl from the lathe and replace the drive center/faceplate with your chuck. Then mount the bowl's tenon into the chuck. Until you get good at remounting (there are various tricks you can use) you will likely find that the bowl is not centered quite the same as it was in the first mounting and you will have to refine the outside to correct this. (read through the next paragraph before you get hung up on this by the way.) Now the bowl is held in place with the chuck and what will be the opening of the bowl is facing where the tailstock is. Remove the tailstock and hollow out the bowl. Since you are doing an open bowl your bowl gouge will be just fine, no need for hollowing tools. You only really need those when the opening of the bowl starts to get seriously smaller than its overall width. A bowl gouge can't reach under the shoulders at the rim of the bowl and that is where your hollowing tools come into play.

Now.....if you are doing all this as a rough turning you will keep the final wall thickness about 10% of the width of the bowl. For most bowls that means about 3/4 to 1 inch thick. And of course you are not very concerned with how smooth the bowl is because you will be setting it aside to dry and will remove a lot more of the wood later on as you finish turn it. It will be way out of round by then. If you are going to go for the whole enchilada in one pass though you will want to make sure that your outside is smooth and complete before you hollow the bowl. That way you have a fixed outer surface to shoot for as you work on the inner surface. Your goal of course is to make sure the inside diameter of the bowl does not become greater than the outside diameter. <grin> Also, if you are doing this in one shot it is good to keep working so things don't have a chance to warp on you.

You asked about speed? First, you need to be comfortable with whatever speed you choose. As a rule though, I will run the speed up until I get vibration, then back it off a bit until it stops. As the bowl becomes more rounded and symetrical you will you find you can increase the speed. I find that higher speeds are generally easier to work with than slow speeds. Again, use vibration and your comfort level as your guide. Typically I end up around 600 to 800 rpm on a balanced piece.

For pieces with knots I may still work at the same RPM, but I may take lighter cuts to avoid the catch you described. You may also want to sit down with someone and go over your technique a bit. This is a great time to work on that before you develop bad habits.

Lastly, Michael (michaelmouse as he is known in his posts) does his hollowing a different way. Hopefully he will chime in and descibe it better, but basically he hollows with the tail stock in place, resulting in a kind of post that remains at the end of his hollowing. This gives him the maximum amount of support through almost all of his workiing time. Then he finally turns off that post at the very end. This is a very safe way to work.

Hope this helps and is not too much at odds with everyone elses techniques!! And have fun tonight!! Relax, go slow, stop periodicallly and loosen up your neck and shoulders. If you are catching stop and look at your tool and body position. Think back to the basics and then continue. This is your first bowl. Remember to hoot and laugh too!

Dave

 

[waltben]

Bowls

As you can see, there are many of ways to turn a bowl (and sometimes people get pretty passionate about it!). I've pretty much settled on starting with a faceplate screwed to what will become the inside, turning the outside and a expanding jaw socket foot. I usually sand to 340 grit before mounting the chuck and checking that it's running true. Then I reverse everything, remove the faceplate and turn the inside. Most of it's finished then and I sand to 1,200 grit. I use a vacuum chuck to reverse the bowl and turn off the socket evidence, and sanding the bottom. I very seldom use my tailstock (it's sitting in the corner of my shop, gathering dust), and have used this process for up to 30" diameter pieces (I've a Stubby) over many years. If I've got a really heavy or out of balance blank, I'll drag out my tailstock, but that's the only time.

 

[ahoiberg]

thanks a lot for everyone's input, it's greatly appreciated and will help me out tremendously.

one last question... what type of screws would be best suited for faceplate connection? and i'd need to true the face first off, correct?

 

[MichaelMouse]

No doubt in my mind that a recess to limit the spur drive is a good idea. They weren't made to work in face grain, and wet wood is even weaker than dry, so you're likely to dismount with a catch. Alternatives include turning the outside on a faceplate, reversing to a chuck hold of your flavor, or my favorite, the pin chuck. Could do a lot worse in convenience, safety and versatility than investing ~$70 in a pin chuck. Bore a 1" hole that you can bottom in and it works great for interrupted or flat rims and means you don't have to change jaws on the other chuck!

I leave the pillar in, using a poke, roll and pull for hollowing in the vicinity. you can see the maneuver in these videos if you have the bandwidth. http://s108.photobucket.com/albums/n28/MichaelMouse/?action=view&current=HollowOne001.flv Shows a dummy who doesn't even know enough to tighten the toolrest when leveling the face at 360 RPM with a straight pull cut. It's still slow because it's a big wet lump I didn't trim up very well before cutting the outside. Not that it hurts to keep things slow all through the process.

http://s108.photobucket.com/albums/n28/MichaelMouse/?action=view&current=HollowTwo001.flv Shows a speedup to 680 because I got around to it, and the basic poke and roll techniques. Some may argue about entering below center cutting from the rim, but I find it pretty catchless even with a bowl gouge. Completely when peeling for smooth with a forged pattern. http://s108.photobucket.com/albums/n28/MichaelMouse/?action=view&current=CherryPeelIn.flv This is a dry piece, as your ears will tell you, so the pillar was taken out when it reached finishing cut stage to make room.

Leaving the pillar on a green rough allows me to drop a 1" bit down the hole after things have dried and do the same for the dry that I did for the wet. Comes out only at the last when the bowl's as light and balanced as it can ever be. http://s108.photobucket.com/albums/n28/MichaelMouse/?action=view&current=PillarSmall.flv I should be poking a tad above center to protect myself against a catch, but I get away with it most of the time. Parting tool will do most of it if you care to.

If you think your speed's too fast, it is. If your lathe oscillates, your speed's too fast for conditions. Other than that, there ain't no rules. Double the speed brings the wood by twice as fast, at four times the available catch energy. Since I am in no hurry, 680 is as high as I go. I don't sweep the tool much faster, so twice the revs don't translate to half the time. Ten minutes, tops, inside.

 

[David Somers]

thanks a lot for everyone's input, it's greatly appreciated and will help me out tremendously.

one last question... what type of screws would be best suited for faceplate connection? and i'd need to true the face first off, correct?

Andrew,

Number 12 or 14 sheet metal screws work fine, whatever will fit through the wholes of your faceplate. Don't use wood screws. they don't have a good thread configuration to really hold well. The length you want would depend on the thickness of your faceplate. Basically though, the more screw in the wood the better (until it interferes with the bottom of the bowl of course <grin>)

So far as facing it off, usually just a decent cut with the chainsaw or bandsaw is enough. You just want a fairly flat surface for the faceplate to rest on. Unless you are Alain Mailland and use big lag bolts and chains to hold your wood to the faceplate. <grin> but then, he is in a whole nother league!!

Also, I noticed that MichaelMouse posted right after you with the links to the videos of his particular technique. He has some interesting ideas that are worth looking at. I haven't felt the need to take his approach, but then I will probably be the one with the turning blank adorning my forehead some day, not Michael. <grin>

Dave

 

[Peter Skellenger]

I am no expert but I would say Andrew is right on track by asking! The first time I saw a bowl attempt was my Dad who had no idea what he was doing. It was brutal to say the least and hillarious to me now! Let's say that drywall screws and 1200 rpm are not really the way to rough turn a big ol chunk of wet sugar maple! I have had flying bowls of my own though, as I am sure most people have had at one time or another. The lathe is an extremely dangerous tool. It's not as intimidating as a table saw (I have seen fingers cut pretty much off in a tablesaw... not mine!) or bandsaw (I did cut the heck out of my thumb once on a bandsaw blade in too much of a hurry using a dull blade!) but is just as danderous IMHO! I have become fully addicted to turning the last cpl years and have been completely self taught but I read everything i can get my hands on about turning. I wish I would have had a lesson or 2 while learning the very basics. Nick Cook has had a cpl excellent articles in the AAW journal on how NOT to turn. Staying out of the path of the wood when turning the lathe on, turning the spd down before shutting it down are 2 excellent things that come to mind. I love faceplates for roughing bowls (not end grain) for the simple piece of mind that the wood is actually "bolted" to the lathe. I turn the tenon once the wood is trued up and then grab that with the chuck to rough out the interior. Anyway- people actually get hurt bad turning. If you happen to be in the path of a flier, you may not be able to finish it off!

 

[ahoiberg]

well... just wanted to update everybody on my bowl's progress. unfortunately, it's in the waste bin...

i had to wait a few extra days to start it and consequently, it got a few cracks in in while drying in it's new shape. i figured, no big deal, i'll just turn down to them and start fresh... they were pretty deep. is this common with cherry?

so, notwithstanding the cracks, i figured it's good practice, so what they hay. so, i turned it round, turned a tenon, started the bowl shape... i was pretty happy. then i took it out of the centers (decided not to use the faceplate, BTW and it went as smoothly as possible for a newbie!) and mounted it in the chuck, refined the outside a little more and started hollowing. i learned some lessons with a few catches that the angle is of utmost importance with that gouge. i kept catching, catching, catching and finally realized that as you hollow bowl gets deeper, you really have to enter with a steeper angle each time you start a new cut... lesson learned.

so, i was well on my way to making a functional, albeit cracked, bowl. and then i had the catch to end the whole process. i was getting the wall too thin and knew i wasn't at the right angle starting a new cut and BOOM, catch near one of the cracks and it blew out part of the side.

anywho, thanks a bunch for all your input, it really helped. and NEXT time, with a little more patience and attention to detail, i really hope i can finish a bowl!

it'll have to wait a while though as i'm moving back to iowa for grad school in a few weeks and the shop is all packed up until i find a place and time to unpack everything.

thanks again!

 

[David Somers]

Andrew! Good luck with Grad School! What are you going for??

A shame you have to stop turning while there. Hunt around for some turning buddies who might let you on the lathe! Could be a good form of stress relief after a long day as a slave (sorry...as a grad student. <grin>)

Good luck!!

Dave

 

[MichaelMouse]

i learned some lessons with a few catches that the angle is of utmost importance with that gouge. i kept catching, catching, catching and finally realized that as you hollow bowl gets deeper, you really have to enter with a steeper angle each time you start a new cut... lesson learned.

Revise your lesson a bit. Your entry angle is always the same, as close to perpendicular to the grain as possible on the initial poke. Then the roll varies to get the bevel on the wood you just cut for stability. That bevel's important, because the faster speed toward the rim wants to grab the tool and hack it in. More steel you have resting on the wood, less likely it is. Support and stability!

Got that toolrest in tight? Coming in a touch below center so you can't be "topped" by uncut wood?

 

[hockenbery]

Andrew,

You are near some of the best wood turners in the world and they share what they know in their local clubs.

AAW chapters in Denver, Boulder and Ft Colliins are quite strong!!
I'm sure these clubs would welcome you as a guest and give you an opportunity to see how other folks use their tools. They may even have a classes or mentoring session

see for poc's ( give Wirsing a call)

http://woodturner.org/community/chapters/members.pl?submit=Chapter+List#CO

Happy Turning,
Al

 

[ahoiberg]

david,

i'm going back for my master's in turfgrass science. and then ultimately, the Ph.D. (if i don't go insane first )

i don't have to stop turning there, just until the move is completed from denver and i can set up in the new garage/basement... only a few weeks of no turning... i think i can survive.

well, at least I'll have dr. rob wallace there to help me out a bit and he tells me that the ames woodturning club is starting an AAW chapter this fall. and there's a lot more trees in iowa!

michael, thanks for the clarification and yep, i kept the toolrest as tight as possible the whole time... can't wait to try another.

 

[woodwish]

Andrew, you beat me to the punch about getting up with Rob Wallace. I met him in Louisville and he is a great guy, very involved with AAW and woodturning. His knowledge of wood from a scientific standpoint mixed with his knowledge of woodturning makes him a very interesting person to get to know. Enjoy your time in Iowa, I have spent many summers up there across the state at UNI helping with some summer institutes. Before I went I heard all the jokes about nothing but pigs and corn but it couldn't be further from the truth, it is a beautiful state with lots of stuff to keep you busy when you aren't busy in school.

I hope next summer if I get back to Iowa to get up with Rob myself on his home turf, or at least share a cold one with him in Richmond! :cool2:

 

[ahoiberg]

i'm actually from ames (where ISU's located), so it will be a homecoming for me... i'm really excited about it. and rob lives right around the corner from my parents house... so, that's equally cool although nothing in ames is too far from anything else.

 

[Gretch Flo]

Nice explanation, Dave Somers

Andrew,

There are a number of ways to do the initial turning and shaping of the outside. ETC
Dave-very nice,concise and precise description. Thanks for taking the time to do this. You must be a writer!!!! Gretch