Work Holding Advice
#11
  
Hello!

I need some advice on holding a piece of wood onto the lathe.

The size of the piece varies from 1" to 1.5" thick, and 4-7" wide. The orientation is face grain.
In the center of this piece is a 3/8" hole that is threaded.

Both sides of the piece are finished.

I have been using tenons with a chuck, but it takes too long and I have to finish both sides. 

I have tried using the threaded 3/8" hole as a point to mount the piece, but have stripped the hole - I guess the forces involved are too high for the short thread length.

I have tried turning a piece of wood with a 3/8" tenon on it. I chuck it up and slide the piece on it. This works ok, but there are points where the piece just spins when being turned (big diameter, small area of friction).

I also tried using 2 cones to mount the piece between centers, but this deforms the hole and makes it unusable, and it spins a lot.

Cant use a faceplate, glue ruins the face, pen mandrel's are too long and not sure that design would hold it well enough.

https://www.woodturnerscatalog.com/p/57/...ll-Mandrel - something like this might work, but it is not the right diameter and is too long.

https://www.woodturnerscatalog.com/p/72/...ning-Chuck - looks promising, not sure it will be strong enough and provide enough holding power for this diameter.

Any other ideas I should try?  

I turn about 15 of these a month, am fine investing time/money in something off the shelf or custom made.

Thank you!
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#12
  Re: Work Holding Advice by peted (Hello! I need som...)
(10-10-2018, 11:11 AM)peted Wrote: Hello!

I need some advice on holding a piece of wood onto the lathe.

The size of the piece varies from 1" to 1.5" thick, and 4-7" wide. The orientation is face grain.
In the center of this piece is a 3/8" hole that is threaded.

Both sides of the piece are finished.
I use my pin jaws for small stuff like that.  Takes a 1" hole, though. 
Can't understand why you can't spin something that light on a woodworm with a chuck, if you wanted.  Take small bites with proper presentation and it won't spin out.


Picture of the finished object would really help those with ideas.
Better to follow the leader than the pack. Less to step in.
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#13
  Re: Work Holding Advice by peted (Hello! I need som...)
You can either replug the hole and redrill with a 1/16 smaller bit or turn between centers of which I do 100% of the time until I go to finish it up and then a small tennon.
It is always the right time, to do the right thing.

Hi, I'm Arlin's proud wife! His brain trma & meds-give memory probs and has pain from injuries, but all is well materially & financially.  
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#14
  Re: Work Holding Advice by peted (Hello! I need som...)
(10-10-2018, 11:11 AM)peted Wrote: Hello!

I need some advice on holding a piece of wood onto the lathe.

The size of the piece varies from 1" to 1.5" thick, and 4-7" wide. The orientation is face grain.
In the center of this piece is a 3/8" hole that is threaded.

Both sides of the piece are finished.

I have been using tenons with a chuck, but it takes too long and I have to finish both sides. 

I have tried using the threaded 3/8" hole as a point to mount the piece, but have stripped the hole - I guess the forces involved are too high for the short thread length.

I have tried turning a piece of wood with a 3/8" tenon on it. I chuck it up and slide the piece on it. This works ok, but there are points where the piece just spins when being turned (big diameter, small area of friction).

I also tried using 2 cones to mount the piece between centers, but this deforms the hole and makes it unusable, and it spins a lot.

Cant use a faceplate, glue ruins the face, pen mandrel's are too long and not sure that design would hold it well enough.

https://www.woodturnerscatalog.com/p/57/...ll-Mandrel - something like this might work, but it is not the right diameter and is too long.

https://www.woodturnerscatalog.com/p/72/...ning-Chuck - looks promising, not sure it will be strong enough and provide enough holding power for this diameter.

Any other ideas I should try?  

I turn about 15 of these a month, am fine investing time/money in something off the shelf or custom made.

Thank you!
I'm having trouble visualizing your situation, pics would help.

Seems to me that you are tapping threads first, then turning. Maybe turn first, tap last?
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#15
  Re: Work Holding Advice by peted (Hello! I need som...)
I also would like a picture of a finished piece.
Janus was a disaster, coming or going - K. L, McReynolds 07/01/2015

My blog: http://wcwoodworking.blogspot.com/
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#16
  Re: Work Holding Advice by peted (Hello! I need som...)
First i assume this is some sort of bowl or platter. What is the purpose of the hole in the bowl and does it extend past the height of the bowl, i.e, the turned over bowl would not sit flat since the hole would cause it to wobble?

Maybe you have thought of this or not but I'll throw it out there anyways. 

Use the worm screw to secure the top of the bowl and turn the bottom and either create a tenon or recess (for the chuck jaws to expand) in the bottom, then sand and finish the bottom on the lathe. Flip it around and secure it either by the tenon or recess and turn the top of the bowl, sand and finish.

If you used a recess on the bottom your done. If you used a tenon you can use a jam or donut chuck and place the face on the bowl on the chuck and hold it against the chuck with the live center in the tail stock. You can remove most of the tenon and then use a chisel to flatten the bottom off the lathe.  If the screw hole goes past the height of the bowl you can drill a hole in the jam chuck so the rim sits flush on the jam chuck.

If i have completely misunderstood your question please ignore me. Laugh
Don
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#17
  Re: Work Holding Advice by peted (Hello! I need som...)
Sounds like you are making a base or a top plate that threads onto a post.

When we turn trivets, we use a piece of 3/4" plywood on a faceplate that is faced with cork and has appropriate sized circles drawn on it. Once we rough the blank to round on the bandsaw, we center on that faceplate and bring up a live center to press it againt the cork for friction. We then true the blank to round and to the correct diameter before changing to the trivet cutting faceplate. You could do something similar but make the cork/plate slightly smaller than you finished diameter. That would let you get it round and do any embellishment that you want for the edge.

The hole from the point of the live center pressing in gives a center mark.

I expect that you have been drilling a tap hole and then using a metal tap to cut the thread. If you wait to do the threading with the tap until after you are finished at the lathe, then any mushrooming of the hole from a jam chuck on the live center would be removed when you do the tap.

Once you get the edge of the disc done, you can switch to a chuck with Cole jaws, or one of those twist chucks that do the same holding. Put a jamb chuck on your live center that is slightly smaller than the outer diameter of your threaded opening, and your piece will stay put while you turn the faces.

You just tweak the hole diameter and thread the hole once you are done the turning.

As others have said a pic of one of the finished widgets would be helpful at getting better answers.
"the most important safety feature on any tool is the one between your ears." - Ken Vick

A wish for you all:  May you keep buying green bananas.
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#18
  Re: Work Holding Advice by peted (Hello! I need som...)
(10-10-2018, 11:11 AM)peted Wrote: Hello!

I need some advice on holding a piece of wood onto the lathe.

The size of the piece varies from 1" to 1.5" thick, and 4-7" wide. The orientation is face grain.
In the center of this piece is a 3/8" hole that is threaded.

Both sides of the piece are finished.

I have been using tenons with a chuck, but it takes too long and I have to finish both sides. 

I have tried using the threaded 3/8" hole as a point to mount the piece, but have stripped the hole - I guess the forces involved are too high for the short thread length.

I have tried turning a piece of wood with a 3/8" tenon on it. I chuck it up and slide the piece on it. This works ok, but there are points where the piece just spins when being turned (big diameter, small area of friction).

I also tried using 2 cones to mount the piece between centers, but this deforms the hole and makes it unusable, and it spins a lot.

Cant use a faceplate, glue ruins the face, pen mandrel's are too long and not sure that design would hold it well enough.

https://www.woodturnerscatalog.com/p/57/...ll-Mandrel - something like this might work, but it is not the right diameter and is too long.

https://www.woodturnerscatalog.com/p/72/...ning-Chuck - looks promising, not sure it will be strong enough and provide enough holding power for this diameter.

Any other ideas I should try?  

I turn about 15 of these a month, am fine investing time/money in something off the shelf or custom made.

Thank you!

Use a waste block with faceplate on each side. Attach the waste block with hot glue, support the piece with the tail stock, turn the face. Brfore you take it off the lathe attach the other faceplate and waste block (already screwed together) by using the tailstock to center it. use hot glue to attach. Then flip it around remove the first face plate, pop the waste block off and turn that face. The hot glue that stays on the turning after popping the waste blocks should peel off. You could also use two sided turners tape/good carpet tape.
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#19
  Re: Work Holding Advice by peted (Hello! I need som...)
You will need to change your procedure , but this chuck will do the job (or one like it, every chuck brand makes one)
https://www.woodturnerscatalog.com/p/105/5457/Vicmarc-10%22-Adjust-Jaw-Set
Life is what you make of it, change your thinking, change your life!
Don's woodshop
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#20
  Re: Work Holding Advice by peted (Hello! I need som...)
Thank you everyone,

I think a wormwood screw would be too large of a diameter, unless I can find something smaller.

I never thought of using cole jaws! I'll order a set and see how that goes.

Until then, I'll give the block with a tenon and tape a try - should be a very similar operation.

Since I have a quantity of these to do, I really want to reduce the time it takes. I figured since I have that hole, I could use it as a way to mount it. Drill hole, tap, mount, turn.  Flip, turn, done.

I have been doing mount between centers, cut tenon, chuck, drill, tap, turn, cut tenon, flip, turn. Clean off tenon. I was fortunate in having 8/4's wood for those.

I'll see what I can do to get an image.
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