How do you mount large blanks?

[corbs]

I've just bolted down my lathe and turned the head outboard. I have a VL120 chuck and a couple of small faceplates so now I'm wondering how you guys mount large blanks (400mm+)? I have a wood screw too but I'm not confident of mounting off that unless someone else with experience advises otherwise :wink:


Corbs

[rod1949]

... so now I'm wondering how you guys mount large blanks (400mm+)?:wink:

verrry carefully :roflmao:

[tea lady]

Face plate screwed on with good screws. :cool:

[bench1holio]

corbs,

screw your face plate to the face side of your blank, then turn a spigot on the bottom side for your chuck to hold.

then hold the spigot with your chuck!!

[Richo12]

:yippy:
side saddle

[dr4g0nfly]

Is it shaped into a round blank already?

If so it should not be too big a problem holding it with either a faceplate or 4 jaw chuck.

If it's a rough shape all out of balance that's a whole different ballgame.

Either way, start at a low RPM and true up before trying anything else.

[DJ’s Timber]

Generally I use CWS Store - Vicmarc Faceplate Rings | Carroll's Woodcraft Supplies (http://www.cws.au.com/shop/item/vicmarc-faceplate-rings) but for the really bigger unbalanced stuff, I use the faceplate.

[corbs]

Thanks team, I have one big blank at the moment. It's got a clean face but is a half back so there's a bit of work getting it balanced/round. The lathe is dynabolted to the slab so slow speeds should be ok. If not I will trim it with the chain saw.

I only have a couple of small face plates though so might make the next purchase a decent size one to hold some big chunks of wood. Does anyone have any recommendations on a particular faceplate?

[brendan stemp]

Does anyone have any recommendations on a particular faceplate?

My favourite faceplate is the one made by Vermec. http://vermec.tripod.com/PDFs/faceplates.pdf

The two features I like are:
1/ you buy one adaptor for the specific thread on your lathe and then you can screw onto it a variety of different sized faceplates.
2/ in the middle is the facility to take a screw. This screw is all that is needed to hold a bowl blank and if you have a big enough faceplate you could hold big bowl blanks just with this single screw. The large surface area of the faceplate provides the support. But if you are not comfortable with this then there are 4 other holes for more standard screws.

[Pat]

+ 1 to the Vermec faceplates. I use 12g square drive screws (http://www.screwit.com.au/online-catalogue/packs-and-specials/pack-specials-multiple-woodturners-pack) for added security. For External turning I have dedicated 1 faceplate to it's Left Hand insert.

Take it slow until the blank is round and vibration free, I start at 50rpm till I am comfortable and then increase the speed in small increments.

[Homeleigh]

Try the The Pop's Shed ConChuck.

Work really well. Have a video on their web site.

[corbs]

Try the The Pop's Shed ConChuck.

Work really well. Have a video on their web site.

Will the ConChuck hold a 15+kg blank? I'd have reservations about mounting a blank that big and heavy off a single point of contact. I do like the look of the Vermec ones though and the versatility of changing the sizes works for me too.

[robo hippy]

We Yanks really need to switch to metric..... Any way, for blanks up to 16 or 18 inches, I usually drill a recess in the top and expand my chuck jaws into that. I do use tailstock support for the bigger bowls. When they get beyond that size, most of the time, I will use a big face plate. I do use a big forstner bit on the drill press, and the depth stop to drill out a flat spot on the top side of the blank. You can get away with it not being perfectly flat on some smaller pieces if you have lots of screw holes, but still flat is best. I guess you could use a screw chuck, but I would want big jaws on the chuck, dead flat for the jaws to sit on, and tailstock support.

robo hippy

[orraloon]

I use a face plate and hex head roofing screws on the top end of what will be the bowl. 4 of those at 50mm long will hold a big heavy out of balance blank. When it is round and balanced then i reverse it on to a chuck to hollow out. I have not checked the weight of the blanks but I guess I have done some in the 15 to 20 kg range this way. The roofing screws can be used many times over and some of mine have been going for years.
Regards
John

[Willy Nelson]

Hi Corbs
1. Determine which side of the blank will be the top. I place this side against the fully open jaws of my VM120 chuck. I bring the tail stock up and clamp the disk.
2. Using my new Arbortech Turbo plane, and slowly rotating by hand, I remove the high spots until the blank is balanced.
3. Start the Lathe (and stand back) at a speed which you are comfortable, slower the better.
4. Continue to true the blank.
5. Turn a spigot, doesn't have to be prettty as this will be the top of your bowl
6. Place your newly turned spigot into the jaws of your chuck and commence turning operations.

or

Using a forstner bit, drill a hole suitable for your chuck jaws on the top of your blank and continue from step 3
Hope this works, and hope to see some photos
Willy
Jarrahland

[Paul39]

I have a 1995 20 inch swing Woodfast short bed with variable speed. All my timber is picked up here and there and roughed with a chain saw, so is out of balance. I screw the top of the bowl to a 8 inch cast iron face plate, bring up the tailstock and make it round, starting at about 50 rpm. As the balance gets better I increase speed.

When the outside is roughed and the blank mostly balanced, I pull back the tailstock and and flatten the bottom and make a spigot or recess for the chuck. I tidy up the outside and remove the blank from the face plate.

I mount the bottom spigot or recess to the chuck and bring up the tailstock center again. I flatten what I can reach, make the rim and hollow as much as I can, leaving a long spigot coming from the bottom of the bowl to the live center.

I pull back the tailstock, thin the bottom of the spigot, break it off and finish roughing the inside.

As I like crazy grain, partially rotted, spalted, timber or stumps with holes in them, there are many opportunities for catches. I like having the additional support of the tailstock as long as possible.

The bowl below is 1/2 of a locust stump. It was hard as stone and abrasive. I had screwed it to the face plate with four #10 screws, I was not using the tail center, had a catch, and it broke two of the screws, tore the other two out, and the blank flew 20 feet into the yard.

[corbs]

Thanks for the input team. Supporting with the tail stock isn't an option as I'm looking to go bigger than the swing on my lathe so have the head turned outboard. The way I mount the blank will have to be strong enough to hold the unsupported blank. I'm happy with the large faceplate method at the moment but I'm also thinking of making a template for a bearing guided router bit which could cut a rebate and then mount on the VM120 in expansion mode. I think the two faceplates I have now are only ~75-100mm so I'm looking at a bigger faceplate before you see any big bowls from me unless I get the router method to work :D

[Tony Morton]

I've used the vicmarc 120 in expansion mode to mount a 16 mm ply faceplate with 600x200 40 kg burl blank no problems ,keep the tailstock up while working on the outer diameter Then turn a 110mm spigot on base and mount in compression mode with shark jaws on the 120 vicmarc but at this size and weight speed was only up to 200 rpm.

Cheers Tony

[NeilS]

Thanks for the input team. Supporting with the tail stock isn't an option as I'm looking to go bigger than the swing on my lathe so have the head turned outboard. The way I mount the blank will have to be strong enough to hold the unsupported blank. I'm happy with the large faceplate method at the moment but I'm also thinking of making a template for a bearing guided router bit which could cut a rebate and then mount on the VM120 in expansion mode. I think the two faceplates I have now are only ~75-100mm so I'm looking at a bigger faceplate before you see any big bowls from me unless I get the router method to work :D

I do all of my bowl turning outboard, regardless of size, without any tailstock support.

Almost any faceplate design will do the job, just increase the faceplate diameter and number & length of screws as the bowl blank increases in weight and diameter.

My current preference is to use a single centre screw on blanks up to 300-350mm (if in doubt, add one peripheral screw), a 100mm ring on blanks from about 300 - 450mm (3 screws is usually sufficient), a 130mm ring on most blanks above that (6 screws), and very occasionally I dig out a 200mm faceplate for anything that is almost too heavy for me to lift onto the lathe.

I use various sizes of hex headed metal roofing screws to fix the ring to the blank with a drill (don't use the ratchet on the highest setting, you need that to get them undone... :~). I drilled out the screw holes in the ring to take larger diameter screws and countersunk the screw holes on the reverse (bottom) side to allow the wood pulled up by the screw to go somewhere without causing the ring to be raised off the face of the blank.

I only ever lost one blank off a ring; had the deep 100mm PowerGrip jaws already on the chuck and they let go of the ring (too much flex in the metal with the long jaws). Didn't make that mistake again and now only use the standard length jaws with the rings and have not lost one since then.

Unless I'm green turning, I complete the outside of the bowl before reversing to turn the inside... when turning outboard you don't have the use of a tailstock to help with cleaning up the foot after completing the inside of the bowl.

The blank in the following photo was getting up there near my weight limit so went to a 200mm faceplate, but it was only just under 600mm so possibly could have done it on a 150mm ring with the VM120 chuck.


236730

[Paul39]

Corbs,

Here is a photo of Ed Mouthrop with a piece hung on a face plate.

http://chronicle.augusta.com/sites/default/files/editorial/images/spotted/53/535514.jpg

Somewhere on the internet I have read about the method, it involves a steel face plate and several grade 8 lag screws.

Do some research on Google, there are quite a few people who do huge pieces mounted on a face plate.

This guy does what I do: The Penland Sketchbook » Blog Archive » A Great Big Bowl (http://www.penland.org/blog/2012/05/a-great-big-bowl/)

Starting with the tailstock and finishing with just the piece hung on the face plate.

This guy works big and supplies his email address, you might ask him how he secures his blanks. I would not want to be in the neighborhood if that came off the lathe.

Dave Barkby Wooden Wall Sculptures - Home (http://www.barkbywoodsgallery.com/page1.aspx)

Gary Stevens: Process And Views Of The Stevens Property (http://got.net/~burly/Process/Process.html)

And then there is this: The Big Bowl (http://www.proserpinewoodturners.com/The_Big_Bowl.html)

[Paul39]

Looking for ideas for a stand for my new bowl lathe I found more big turnings on a face plate:

http://www.lindquiststudios.com/images/DOWEL_BOWL/Mark-BigBowl-029.jpg

http://www.treeworld.info/attachments/f39/8259d1224963603-burl-bowl-img_3463.jpg

150mm face plate: http://sawsndust.com/images/ellsworth/jb-ellsworth-1.jpg

This one boggles my mind, the spindle is mounted to a poured in place concrete block:

http://i.imgur.com/8pvrq.jpg

[robo hippy]

I would guess for safety sake, with no tailstock, you would want a blank to face plate ratio of at least 4 to 1, and 3 to 1 or higher being better (20 inch bowl/5 inch or bigger face plate). The more screws the better, and if you are screwing into end grain, angle your screws, not straight in.

robo hippy

[NeilS]

...and if you are screwing into end grain, angle your screws, not straight in.



Good tip...:2tsup: