Turning Large Bowl Blanks
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Turning Large Bowl Blanks
Has anyone had sucess turning bowl blanks in the 14" area. I cut a 14" x 2" round blank on my bandsaw put a faceplate on it and it shook pretty violently. I haven't tried a 12" yet. The wood had about 14% moisture.
I have yet to turn anything that large, but, I think the speed reducer is made
to help with this issue as well as large bit drilling.
to help with this issue as well as large bit drilling.
Mike......... Rowlett, Texas, near Dallas
86 MK V 500/520. 59 MK 5 Greenie Shorty. SS Jointer, SS Planer,
SS Bandsaw, SS Lathe duplicator, SS Belt Sander,SS Molder & Shaper,
SS Tenon master jig, SS Mortising kit, SS 2 1/4' Drum Sanders, Ringmaster, DC3300....
86 MK V 500/520. 59 MK 5 Greenie Shorty. SS Jointer, SS Planer,
SS Bandsaw, SS Lathe duplicator, SS Belt Sander,SS Molder & Shaper,
SS Tenon master jig, SS Mortising kit, SS 2 1/4' Drum Sanders, Ringmaster, DC3300....
If the two surfaces of the wood you are using are parallel, as in planed lumber, then you shouldn't have a problem turning something measuring 14x2 provided it was centered on the face plate. If you mount it on the spindle as it is currently mounted to the face place, simply put the tool rest about a 1/2" away from the rim of the blank and turn the blank by hand. You'll see exactly how well you've centered the stock. If it's not perfectly centered, hold a pencil or marker against the stock and rotate it. You can then re-trim the stock on you bandsaw and everything should then be balanced and ready for turning.
The moisture content shouldn't affect the balance, although it is a bit high and you likely will have a bit of shrinkage across the grain after turning as it dries further.
The moisture content shouldn't affect the balance, although it is a bit high and you likely will have a bit of shrinkage across the grain after turning as it dries further.
Art in Western Pennsylvania
Pennview - nice tip!! Also, with 14% moisture content, turn a rough blank, and cover the outside with brown paper, and tape at the rim. Wall thickness should be about 10% of the diameter (1.4" if it stays 14" diameter), and wait a few weeks for the moisture to evaporate from the interior. Then re-chuck and re-true and finish it up. It will help to reduce the warpage. Don't ask how I know. Wet wood is great to turn, nice curls, but warps like a son of a gun later. Perfectly round bowls will be oval in a matter of a few weeks (or days) depending on the environment you set them into.
BTW: without a speed reducer, if you have access to a dedicated lathe, turn the rough bowls there and the finish on the SS. That's what I've been doing and saves a lot of fear factor. I'm too old for those adrenalin rushes anymore.
BTW: without a speed reducer, if you have access to a dedicated lathe, turn the rough bowls there and the finish on the SS. That's what I've been doing and saves a lot of fear factor. I'm too old for those adrenalin rushes anymore.
Hand Engraver of Metals; Maker of Exquisite Kindling; 1955 Greenie Mark V (NOW with a 1989 Headstock); Magna Band Saw; Magna 4" Jointer; Miscellaneous Craftsman & Porter-Cable electric woodworking tools.
3D CADCAM Designs - Gemstone Facetor
3D CADCAM Designs - Gemstone Facetor
It also could be that the blank dried unevenly and one side has more moisture that the other.
SS 500(09/1980), DC3300, jointer, bandsaw, belt sander, Strip Sander, drum sanders,molder, dado, biscuit joiner, universal lathe tool rest, Oneway talon chuck, router bits & chucks and a De Walt 735 planer,a #5,#6, block planes. ALL in a 100 square foot shop.
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Bob
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Bob
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terrydowning
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- Joined: Mon Jul 19, 2010 3:26 pm
- Location: Windsor, CO
Big pieces at 700 RPM is not recommended until they are balanced.
I do love my shopsmith but it does have limitations. Large turning is one of them. While capable of handling the mass, precautions must be taken and you have to pay attention at all times when that big piece is turning (even on a stand alone lathe)
If you have a speed reducer available or can borrow one, Use that for large pieces.
Do your best to balance large pieces before turning at 700 RPM. The SS is too light in and of itself and will dance around with unbalanced pieces moving at 700 RPM.
Make sure that large turnings are securely mounted to the lathe before turning on and nothing is the line of fire including you until it gets up to speed. That big stuff can really move fast when it comes loose DAMHIKT. Out of balance pieces are much more likely to come loose. If using a face plate make sure you are using all of the screw holes and they are all secure. I have had pieces rip loose of the screws.
You can add more weight to your SS by attaching items to the bench tubes, but turning slower by use of a speed reducer until it is balanced is much safer and easier.
Wood turners often site a Shopsmith's relatively light weight and high rotational speed as a weak spot and I agree. The truth of the matter is, SS is not in the same league as a powermatic, oneway, robust, or other large stand alone lathes for large turnings. That being said, it can get the job done and I have seen large pieces come out beautifully using the SS. BTW has anyone priced one of the big lathes? I have and let's just say I'll stick with my SS until I win the lottery.
I do love my shopsmith but it does have limitations. Large turning is one of them. While capable of handling the mass, precautions must be taken and you have to pay attention at all times when that big piece is turning (even on a stand alone lathe)
If you have a speed reducer available or can borrow one, Use that for large pieces.
Do your best to balance large pieces before turning at 700 RPM. The SS is too light in and of itself and will dance around with unbalanced pieces moving at 700 RPM.
Make sure that large turnings are securely mounted to the lathe before turning on and nothing is the line of fire including you until it gets up to speed. That big stuff can really move fast when it comes loose DAMHIKT. Out of balance pieces are much more likely to come loose. If using a face plate make sure you are using all of the screw holes and they are all secure. I have had pieces rip loose of the screws.
You can add more weight to your SS by attaching items to the bench tubes, but turning slower by use of a speed reducer until it is balanced is much safer and easier.
Wood turners often site a Shopsmith's relatively light weight and high rotational speed as a weak spot and I agree. The truth of the matter is, SS is not in the same league as a powermatic, oneway, robust, or other large stand alone lathes for large turnings. That being said, it can get the job done and I have seen large pieces come out beautifully using the SS. BTW has anyone priced one of the big lathes? I have and let's just say I'll stick with my SS until I win the lottery.
--
Terry
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Terry
Copy and paste the URLs into your browser if you want to see the photos.
1955 Shopsmith Mark 5 S/N 296860 Workshop and Tools
https://1drv.ms/i/s!AmpX5k8IhN7ahFCo9VvTDsCpoV_g
Public Photos of Projects
http://sdrv.ms/MaXNLX
You got some real good and accurate advice in regards to turning. Sometimes it is an advantage to bring a suspicious turning up to the tailstock and use the tailstock ball bearing center to stabilize the work. It can sometimes help with the shaking.
A friend recently asked me to help him to turn a 4X4 into a small barber pole that he sells at craft shows. 4X4's are inherently NOT square or balanced. I have the PP and ran it at 250 RPM to get the main part round and balanced. There was a 6" long piece at the headstock end that was to remain square. After the initial turning I still could not get above 750 RPM before the shaking started, so it doesn't take much off center or out of balance to get things going. Most lathe turners mark "square" from corner to corner to tell where the center is, but if the stock is not square but a parrallelogram then the diagonals should be drawn from all four corners. The lines will not cross at a common point but will form a small box near the center. The center of the box will be the geometric center of the piece.
A center finder for round stock can be used to mark multiple diameters across thecenter of the disc and these lines also will not cross at the same point but will form a rough circle near the center. The middle of this rough circle will be very close to the actual geometric center. I think that these methods will help a lot to get close to balanced except for the most drastic cases.
Bill V
A friend recently asked me to help him to turn a 4X4 into a small barber pole that he sells at craft shows. 4X4's are inherently NOT square or balanced. I have the PP and ran it at 250 RPM to get the main part round and balanced. There was a 6" long piece at the headstock end that was to remain square. After the initial turning I still could not get above 750 RPM before the shaking started, so it doesn't take much off center or out of balance to get things going. Most lathe turners mark "square" from corner to corner to tell where the center is, but if the stock is not square but a parrallelogram then the diagonals should be drawn from all four corners. The lines will not cross at a common point but will form a small box near the center. The center of the box will be the geometric center of the piece.
A center finder for round stock can be used to mark multiple diameters across thecenter of the disc and these lines also will not cross at the same point but will form a rough circle near the center. The middle of this rough circle will be very close to the actual geometric center. I think that these methods will help a lot to get close to balanced except for the most drastic cases.
Bill V