How to attach Large work to PM?

[Josh Holden]

I've had the mustard a few months now, and I'm starting to explore the potential for larger work. But I'd rather not kill myself.

So far, up to 20", I've been using the 3.25" faceplate that came with the lathe, along with the tailstock for extra support/safety. I have the bed extension with the longer toolrest post, and I'd like to try turning off the end with it. But without a tailstock, I want to make sure the blank stays attached.

So how big a faceplate do I need, for a 26" blank, for example? The Don Pencil stuff has been recommended, but he doesn't seem to have plates over 3.5" -- any recommendations for a source of good plates in larger sizes? The blanks can easily hit 100 lbs. And how many screws/how long? And is it ever possible to put something like this in a standard chuck? (The last 18+" bowl was 20 lbs when roughing was finished). I assume a talon with #3 won't cut it... ?

Thanks,
Josh

[Burt Alcantara]

If you want to go the chuck route you can get a Stronghold, Vicmarc 120/150, Nova Titan. All have large jaws that would hold anything your lathe could support. I've mounted 20" pieces on my mustard using the Stronghold with no problems; rpms past 1k.

For the responders who recommend faceplates, where do you buy yours? I'm looking for 4"-6" and they are expensive!

[Mike Spanbauer]

Just asked a question along these lines (faceplates / cheapest / best) a bit ago. You can search for the detailed responses, but essentially the oneway steel plates are the best and for the best price call up some local machine shops. They aren't too complicated and the screw holes don't have to be perfectly aligned to one another.

Mike

[Matt Haus]

http://www.packardwoodworks.com/Merchant2/graphics/00000001/112834-img.jpg
http://www.packardwoodworks.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=packard&Product_Code=112836&Category_Code=lathes-acc-cent-quic

I use one of these on my talon chuck for large pieces. I am probably going to get critiqued but this works for me when I use a forstner bit to add a level area on the tree bark side and then put the big piece between centers. I usually take is slow and if I want to use a face plate, I can level up the other side or cut out an area for my stronghold chuck.

Probably not the best way but I'm not a fan of screwing faceplate screws into the wood since I do hollow vessels mostly and want the most wood I can get. Now for bowls, the faceplate is the way to go. I've never had a problem using my faceplate for larger pieces that came with the PM 3520b. I just use the tailstock to keep it steady.:p

[Rich Souchek]

Neccesity (sp?)is the mother of invention.......
Went thru this about a year ago, and found my lathe and I are limited by how much weight can be picked up.
Tried several things....
Second and best idea was to make a wood face plate out of srcap that was about 12" dia. Screwed the wood face plate to the balnk with abut 12 2" long screws and then screwed the little steel PM faceplate to the wood blank with the biggest lag bolts that would fit. Then got help to turn the headstock while I held the blank up to get the whole thing mounted.
This actually took a couple of iterations, for the screws pulled out of the blank on my first try and the second was way over sized and safer.
My suggestion is to slowly try what you think will work and chances are it will do fine.
A while after that, a Oneway Stronghold chuck was purchased with their #3 tower jaws with the intent of holding big blanks. It does but the #3 tower jaws are overkill and I'm too cheap to buy the long center screw to use. What has been learned is to buy the longer center screw to easily mount big stuff on this chuck and to get the regular or dovetail #3 jaws to hold big blanks.
Rich S.

[George Guadiane]

For items larger than the swing of the lathe (which is what I think you are asking, think about cost...
How much is a quality 6/8 inch face plate and some #12 stainless steel flat head 2 - 2 1/2 inch screws -
How much might it cost to have an improperly secured HEAVY piece of wood flying around your shop/studio/garage, breaking stuff and maybe injuring you?

My RECOMMENDATION, having had much smaller stuff flying around and breaking stuff, is to go with the face plate and KNOW that you have taken the proper steps to insure your SAFETY.

[alex carey]

Definitely go with a faceplate at least in the roughing stages. I would check out oneway. 6" is probably the biggest you'll ever need.

http://www.oneway.ca/faceplates/index.htm

[Roger Wilson]

Here's a youtube video (two parts) of Blair Davis working on a large bowl blank. It might give you some sense of what's involved.

http://www.youtube.com/watch?v=tM7Krp9e9ZM

[Josh Holden]

Thanks for all the replies so far. I'd seen the Blair Davis video when I first started turning; it's a fun mark of my progress that what looked strange and mysterious then looks so familiar now.

It sounds like the 6" oneway faceplate is the way to go, if I want the no fuss solution. But is there any rule of thumb for the maximum size/weight of a blank compared to the size of faceplate? What's the limit for the 3.25"? The 6"? Will I ever need the 8"? (A 40" blank is my absolute limit.) George is right that safety trumps cost, but the larger faceplates limit access to the bottom.

As for process, I guess I'd turn the outside first on the faceplate as usual, then re-mount the faceplate on the foot for hollowing. Then I'm using up some of the potential bowl depth for the length of the screws. Or can a stronghold really hold a green, 30" blank for hollowing?:eek: And how do I clean the tenon for re-mounting after it's dry?

What about a glue block? Is there a size limit where that becomes a 'bad idea' ? Any other special techniques for mounting extra large turnings?

Its funny -- I never really thought about all the times I use the tailstock, eg with a jamb chuck to take off the foot, or to clean the tenon for re-turning, or just for extra safety. I have to learn to do some of these things all over again.

Josh

[George Guadiane]

George is right that safety trumps cost, but the larger faceplates limit access to the bottom.

As for process, I guess I'd turn the outside first on the faceplate as usual, then re-mount the faceplate on the foot for hollowing. Then I'm using up some of the potential bowl depth for the length of the screws. Or can a stronghold really hold a green, 30" blank for hollowing?:eek: And how do I clean the tenon for re-mounting after it's dry?

What about a glue block? Is there a size limit where that becomes a 'bad idea' ? Any other special techniques for mounting extra large turnings?

Its funny -- I never really thought about all the times I use the tailstock, eg with a jamb chuck to take off the foot, or to clean the tenon for re-turning, or just for extra safety. I have to learn to do some of these things all over again.

Josh

Josh,
I especially like the part about being right (doesn't happen too often at my house)...
However, if you put the faceplate on the inside side of the bowl, then turn the outside, including a tenon for a Stronghold grade chuck - larger/est jaws, then hollow as much from the inside of the bowl, while its still on the faceplate, you can reduce the mass of the whole blank to a point where it is easier/safer to turn it around and mount it with the chuck and finish roughing out the inside.

When you have the inside finished, and out to the foot, you could use the faceplate again to mount a 3/4 inch piece of plywood, turn it to the exact size of the rim, then pallet/stretch wrap the bowl to the plywood...
In theory, that SHOULD give you the back side, fairly well centered and open to finishing.

That would be my approach.

[Dennis Ford]

I am a big believer in face-plates, mine are home-made. A 4" faceplate will hold a very large diameter blank, probably would be ok with 200 lbs if the blank was not very deep and if the wood is strong enough that the screws won't pull out. I think that the length of a blank is more important than the diameter when choosing screws.
I have several face-plates that are 3 - 4" and one that is 6" dia. The 6" one has 12 holes, I use it for end grain hollow forms. End grain does not hold screws as well and long/deep pieces put a lot of stress on the screws. I am finishing a sweet gum piece that is ~ 11" dia x 15" tall, it is held with (12) 1/4" x 1-1/2" lag bolts. I did not need a steady rest when hollowing it.

[Judy Kingery]

Hi Josh,

I'd echo what's been said; face plates are secure work; mine are 2", 8" and 10" for larger pieces. I use lag bolts to anchor the wood to the plates. Never had a problem one with anything coming off, splitting, nothing and I guess the largest I've turned has been now, about 30" or so. I bought my face plates from Craft Supplies USA. Decent price, good work, no problem.

Best to you,

Jude

[Bernie Weishapl]

I second the 6" or 8" faceplate with 2 1/2" stainless steel flat head screws.

[Kim Ford]

Josh;


There has been some really good advice here. One thing that hasn't been mentioned though is the forces that cause faceplate failure. It has been my experience that when you turn large blanks these few things really come into play.

Balance; Spending the time with your chainsaw, sawsall or band saw to get a pretty round blank is important. However, large blanks can be very round and still be tremendously out of balance. Moisture, density and other factors cause this and put a lot of stress on the connection point, (the faceplate)
Speed: absolutely a major factor. The forces exerted on the point of connection dramaticly increase / decrease based upon speed. You have to find the right harmonics for your lathe for each large piece you turn.
Surface area of faceplate: The surface area of the faceplate is a simple leverage thing. The larger the surface area in direct contact with the wood the less stress put on the screws that are used provided that surface area extends the same radius from the center in all directions.
Connection Screws: The holding power of a screw depends upon the diameter, the depth of penetration, as well as the cellular structure and the orientation of the wood you are screwing it into. Also consider the quantity and the placement of screws.
The general rule I use on larger pieces that I can't put between centers is, use the largest faceplace possible, and start the process at the lowest rpm you can work at until you are able to determine the balance and the harmonics, then make light cuts until the blank is totally round.
Just my 2 cents, hope it helps.

[Josh Holden]

Looks like I've got some shopping to do: a 6" oneway faceplate and a stronghold chuck (and maybe an engine hoist :D).

That leaves one question: Without a tailstock (ie, turning outboard), how do you true up the tenon once the bowl dries? :confused: On small bolws I'm satisfied with the "just clamp the chuck tighter" method, but that doesn't seem wise on the big stuff.

And it doesn't seem like a donut chuck / shrink wrap would be accurate enough -- or is that just the best you can do?

Thanks again for all the opinions!

Josh

[Matt Haus]

Josh, why wouldn't you use a tailstock? You can use a piece of scrap and put it in your lathe chuck and make it domed shaped and use a soft piece of towl or washcloth to hold the inside of the bowl and use the tailstock in the center of the bottom. You don't have to turn it fast to true up the tenon. Then just reverse it and put the tenon in the chuck.

Not sure what you are asking.

[alex carey]

If the piece is too big to fit over the bed, is what he is asking.

[Ryan Baker]

If you have to true up the blank outboard, you are going to have to get creative. A donut chuck is probably the best way. Something like an overgrown Cole jaws could work. Or a monster vacuum chuck. Or rig an outboard tailstock. Or borrow use of a bigger lathe. Etc. Depends on the shape and thickness of your blank -- what you have to work with.

[Ron Bontz]

Not to hijack this thread but I was wondering what you guys use to hold a large bowl or platter to remove the bottom? Do you make larger size jumbo jaws or use another method? :confused:

[Kim Ford]

Josh;

Larger blanks turned and finished on the outboard side without a tailstock do call for creative solutions. The donut chuck is probably the easiest for whatever you can't grab with the chuck, provided you have a chuck that will fit on your outboard side. If the chuck is not available a glue block and faceplate along with donunt type chucks actually work pretty well allowing you to hold from each end and finish off the piece.

Just a note, I've never used a donunt chuck with shrink wrap, sounds creative but I just don't know if I would trust it or not.