Mounting large spindle turning, green log blanks

[Jon Moyer]

I am looking for advice on mounting 18" diameter x 18" long green log blanks for spindle turning (no hollowing). I see some people using a faceplate and some using a spur center. I have a Powermatic lathe, and the small faceplate and drive spur center that came with it. Also would like input on the cone vs cup live center. If this has already been covered, just point me in the direction of that thread.

Thank you!

 

[hockenbery]

what are you making.

Note that a block that size can kill you.
Working with large pieces of wood is best done after your skill set matures enough to do it safely. You may be ready to tackle this project but You need to evaluate you skills realistically or ask someone who knows your turning skill for a confirmation.

I used a spur drive to make pedistals for some African stone sculptures using poplar logs that were close to 18” diameters.
if your powermatic tailstock is in good condition it will lock well enough to hold the piece between centers. If you have had any slippage in your tailstock don’t try a large piece between centers.

drilled a 1 3/4 hole 1/2” deep with a Forster bit to help center the a 1.5” spur drive.
I used the cup center on the tailstock. It pushed into the poplar a good bit for a solid hold.
If your wood is really hard you might drill a small hole for the tailstock center too.

A cone should be ok for a super thick spindle. I don’t use them for small spindles
The white on the log end is anchorseal.

 

[Dennis J Gooding]

Given the massive inertia of the piece, a small spur center will not do the trick. It will just rip a groove in the end of the piece. However, I would expect that a 3" D or larger faceplate with lots of screws would do the trick. A cone center driven 3/8" or so into the other end would be my choice.

 

[Doug Freeman]

I have successfully used just a 1” spur on 16” diameter x up to ~17” long green logs, and used a cone center. It does require paying attention to the chip load and interrupted cut impact load. As mentioned the tailstock needs to hold very well, and pressure on the wood checked often with green wood, as the cone will easily push into the wet wood.

I have also used a 2-1/2” Elio drive which works better than the 1” spur, but I’m moving away from spindle taper mounted drives with large projects due to concern over wear of the taper. I have a Nova jumbo center on the way - it screws onto the spindle. There are other options as well. Even a small face plate will work well to drive with, but I find it to be a chore to get the TS cone where I want it and a properly mounted faceplate, so I dont use them starting out. For hollowing I mount the work between centers, adjust orientation, turn a slightly concave surface and mount the faceplate. Another option is mount between centers long enough to turn a tenon, and then mount in a chuck.

Per previous comments, hopefully you have built some knowledge and experience by stepping up thru larger and larger log blanks.

 

[Don Wattenhofer]

The cup center is always the best way to go for any size turning because it will provide much more force against the work piece whereas a cone center will keep working into the end.
For the drive end a disk of 3/4" flooring grade fir plywood the kind with no voids attached to the 6" face plate with all possible screws, then at least 8 3" construction screws thru the plywood and into the blank.

Working with large pieces of wood is best done after your skill set matures enough to do it safely. You may be ready to tackle this project but You need to evaluate you skills realistically or ask someone who knows your turning skill for a confirmation.

no sense rewriting this and start slow don't get any caches

 

[Jon Moyer]

Thanks everyone for pointing out the safety concerns, that's definitely why I came here for wisdom and advice. The project is for a friend that wants some stools and stands for his garden, pretty much smaller versions of hockenbery's African stone sculptures. The wood is from his property and there's a choice of beech, ash, elm, or red oak. I've got 30 years of woodworking experience, but only 10 months of turning. I have roughed out 60 plus bowls in white oak, dogwood, beech, maple and most recently some 18" dia green sweet gum that was very heavy. The lathe was new 6 months ago. I'll get a larger spur and try some smaller pieces first. Thank you!

 

[hockenbery]

I'll get a larger spur and try some smaller pieces first. Thank you!

Great idea. Do a 6” piece as a model do an 8 or 10” piece for transition.

Google - Liam O’Neil garden sculptures
for inspiration.
Liam taught me how to use the side ground gouge.

 

[John Tisdale]

I would take Hockenbery's advice to the bank.
I generally drill a 1.5" hole with a forstner bit and use a 1.5" "jumbo" drive - 1.2" deep is good.
If your lathe has a braking system, switch it off. Then ramp up and ramp down.
If you don't have, spend the $100 on a Oneway live center - you'll be hugging yourself.
Good luck

 

[John Tisdale]

Oops - meant 1/2", not 1.2"

 

[Dennis Weiner]

Logs that size, I start off by using the one way cup safety drive because it has the identical cup footprint as one way live center. There are times after the bark is removed that I may want to flip the log. With this setup, you can Avoid dealing with dissimilar center holes. Also, There is more than enough pressure to prevent slipping in most cases.
If it does slip, then it’s a good signal that the wood has moved and time to tighten the tailstock.

If no one has mentioned it above, it’s a good idea to stop the lathe and tighten down the tailstock frequently with stock this large.

Usually, I’m making a hollow form, so if I was working on an 18x18 log, I would true up the end(slightly concave) and use my 10” faceplate with at least 12 3” lag bolts. Sometimes I may make a tenon at the end of the log so that the faceplate fits snuggly. Additionally, I sometimes use a band clamp around the log where the screws live.

 

[Dennis Weiner]

I have successfully used just a 1” spur on 16” diameter x up to ~17” long green logs, and used a cone center. It does require paying attention to the chip load and interrupted cut impact load. As mentioned the tailstock needs to hold very well, and pressure on the wood checked often with green wood, as the cone will easily push into the wet wood.

I have also used a 2-1/2” Elio drive which works better than the 1” spur, but I’m moving away from spindle taper mounted drives with large projects due to concern over wear of the taper. I have a Nova jumbo center on the way - it screws onto the spindle. There are other options as well. Even a small face plate will work well to drive with, but I find it to be a chore to get the TS cone where I want it and a properly mounted faceplate, so I dont use them starting out. For hollowing I mount the work between centers, adjust orientation, turn a slightly concave surface and mount the faceplate. Another option is mount between centers long enough to turn a tenon, and then mount in a chuck.

Per previous comments, hopefully you have built some knowledge and experience by stepping up thru larger and larger log blanks.

For the Elio drive, you can use a drawbar if the powermatic allows it. It will prevent any slippage.

 

[Owen Lowe]

Here's another method:
Use a faceplate on both ends! It will be very secure on the lathe with hardly any chance of the mounting method failing.
You'll need two face places, the Oneway-style tailstock live center, and an adapter for the live center to second faceplate's thread size.

1. Attach the headstock's faceplate to the wood and mount the log on the headstock.
2. Attach the live center adapter to the second faceplate and mount the assembly on the live center. Bring up to the wood and lock the tailstock.
3. Screw the tailstock's faceplate to the wood and you're finished.

This will result in the turning being very securely held at both ends. The drawback of this is that you have less flexibility to remount the log if a different center is desired.

As an aside comment: If you are ever using a faceplate, this project or others, make sure you use screws that can withstand shear forces. Drywall and standard wood screws don't have the strength to serve as faceplate screws. I use Tapcon concrete screws available from my local Ace Hardware. They are a coated, high-strength screw that won't break or stain wood if mounted for a while.
https://www.tapcon.com/products/genuine-tapcon-screw-anchors/genuine-tapcon
https://oneway.ca/index.php?route=product/category&path=119