Mounting bowl blanks to a face plate

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mick

mick

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Got a question or those of you that turn bowls or vessels using a face plate.

I turned a hollow form vessel tonight using the faceplate that came with my Jet Mini. Screwed the blank to it using some #6 Screws They held it fine ...no problems there but what I had happen was after I shaped the outside of the vessel and got ready to take it off the FP, 3 of the 4 screws twisted off, or were already broken or near so. I'm assuming it was caused by the shock or stress of turning the vessel.

Question is should I use "hardened" screws?
I also thought about drilling out the holes in the FP to fit bigger screws. What do you more experienced turners do?

Thanks,
Mike
 
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Sheet metal screws with large cross section hold securely for faceplate -- but a stub tenon and the scroll chuck is handier and does not leave screw holes to be plugged - or glue the bowl blank to waste stock mounted on the faceplate and part it off.
 
Hi Mike,
My experiences has always been that the hardened screws were MORE likely to snap off at the head than "softer" wood screws. If you want to use the faceplate, I would recommend screwing a waste block to the faceplate and then using CA or epoxy to glue your blank to the waste block. Slipping a piece of brown paper bag in between the waste block and the blank, will make prying it off easier. If you think you are going to turn a lot of bowls, I would recommend a 4-jawed chuck. It's the only thing I use now.
 
Ok I'm just flying by the seat of my pants here but here's what I did:

1.Mounted my blank to the face plate

2. Turned outside to shape and sanded plus turned a foot on the bottom of the vessel about 1/4" deep

3.removed it from
the faceplate and mounted on my 4 jaw chuck inside the foot I turned

4. hollowed out the insides and, sanded and finished.

So you're saying I need to use the chuck to shape the vessel? What do I do, turn a tennon on a waste block to fit the jaws and then mount it?
 
I usually just turn the outside between centers and form the tennon for the foot. I then mount in the chuck and turn the inside. I then use a friction drive and reverse the piece so I can turn off the foot and finish the bottom.
 
Mick, other than your screw problems - don't use drywall screws - your sequence is what I do other than I start the same was as Curtis, between centres.
 
rlharding said:
Mick, other than your screw problems - don't use drywall screws - your sequence is what I do other than I start the same was as Curtis, between centres.
Click to expand...

These were good quality wood screws....Had to dig the dang things out before I could hollow the piece out!
 
#6's are pretty thin. I agree on the sheet metal screws. I also mount on the face, turn the foot with a recess and rough the outside, and as much of the inside as I can with the tailstock in place. I then chuck mount it to finish turning. The only issue I have had this way is not taking into account the depth of the recess and making the bottom a little too thin. I think next time I will use a drill chuck and a forstner bit to pre-drill the depth of the bowl to keep that from happening again.
 
you didn't say what type chuck you have but I use the "woodworm screw" that mounts in the jaws of my nova chuck to rough and shape the outside of bowls if you can get one to fit your chuck it makes things much easier.
I have roughed out many VERY out of balance blanks and off center blanks this way and have never had the screw strip out or loosen at all.
 
The only time I've had a screw snap on me was when I overtightened it initially because I was overaggressive with the drill, and it bent/snapped at that time. My guess would be that you are an overtightener like me, or maybe you were a bit hard on the wood during turning - or a combination of both.

But... to answer your question, I mount with whatever screws I have handy, as long as the length fits. Sometimes they're sheet metal screws, sometimes they're drywall screws, and they can be of any thickness - so long as the length is right. But more often than that, I just use a screw chuck, either the woodworm (like Cyclops), or a 2MT screw chuck with a smaller screw.
 
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No.6 screws are kinda thin.

I mount my bowl blanks using a faceplate usually with #10 or sometimes #8 hex head sheetmetal screws, and turn the outside to shape, making a tenon for the four jaw chuck when turned around to hollow the inside.

I use to use only brass screws, but everytime I took them out, their softness being brass would strip out the slots and I would have to toss them out.

Started using the hex head sheet metal screws and using a nutdriver can use them a number of times over.
 
The only thing you are doing wrong is using the wrong screws. When I took a bowl turning class the instructor, a 25 year veteran turner, said NEVER use wood or drywall screws. They will break. Use sheet metal screws. Use the largest ones that will fit through the faceplate, usually #10 or #12. Also, of you are attaching to the end grain it will not hold as well so you will want to use longer screws if you can.
 
JimB said:
The only thing you are doing wrong is using the wrong screws. When I took a bowl turning class the instructor, a 25 year veteran turner, said NEVER use wood or drywall screws. They will break. Use sheet metal screws. Use the largest ones that will fit through the faceplate, usually #10 or #12. Also, of you are attaching to the end grain it will not hold as well so you will want to use longer screws if you can.
Click to expand...

That's the thing..the holes in the Jet face plate were so small only a #6 would fit....I'm thinking about drilling them out so I could at least use a #10 oe even a #12

I did dig out my wood worm screw that came with my chuck. I think I've figured out how to use it. I'll try it next time.
 
Yep, no drywall screws. I use decking screws or sheet metal screws, with hex heads, and never smaller than #10. Mostly I use the woodworm screw in a scroll chuck, and save the faceplates for big stuff, well above mini-lathe size. If you plan to turn a lot of bowls, you'll want a scroll chuck anyway.
 
You will like the woodworm screw much better. That is actually what I do. I have not done a bowl in a while and forgot about that. Just drill a hole the size of the diameter ofthe "shat" of the woodworm screw minus the threads. Do it in the portion that you will be hollowing out. Then I turn on the lath on slow speed and let the lath thread the blank onto the screw. Get it good and tight and use the tailstock for extra security until you need to do the bottom. Then make your tennon or recess and switch it around. You will already have the chuck install so you will not have to removethe face plate and put on the chuck.
 
Get solid screws (#10) I prefer those that use a square driver - I use 1.5" screws. Start the hole and if the going gets tough put a drop of dish soap on the screw. As many do I only use the face plate to rough close to shape and turn a 'foot' for my chuck jaws.

Marc
 
me2cyclops said:
you didn't say what type chuck you have but I use the "woodworm screw" that mounts in the jaws of my nova chuck to rough and shape the outside of bowls if you can get one to fit your chuck it makes things much easier.
I have roughed out many VERY out of balance blanks and off center blanks this way and have never had the screw strip out or loosen at all.
Click to expand...

I have been reluctant to use those because they don't look like they would hold a larger piece securely. How big a bowl can/do you hold with those?
 
I have done up to a 11" winged bowl in super dry hard purpleheart and roughed vases ~10" tall (with a live center for the vases)
drilled 5/16 hole for the screw.
 
Rifleman1776 said:
I have been reluctant to use those because they don't look like they would hold a larger piece securely. How big a bowl can/do you hold with those?
Click to expand...

Frank,

I have done a 15 7/8" shallow bowl with my woodworm. My lathe has a 16" swing and I just barely cleared the bed. I keep the tailstock up until I need to shape the foot but even with it off, it is secure.
 
MesquiteMan said:
You will like the woodworm screw much better. That is actually what I do. I have not done a bowl in a while and forgot about that. Just drill a hole the size of the diameter ofthe "shat" of the woodworm screw minus the threads. Do it in the portion that you will be hollowing out. Then I turn on the lath on slow speed and let the lath thread the blank onto the screw. Get it good and tight and use the tailstock for extra security until you need to do the bottom. Then make your tennon or recess and switch it around. You will already have the chuck install so you will not have to removethe face plate and put on the chuck.
Click to expand...

This works most of the time, and If you are doing a small mouthed opening in the bowl, almost a must.... but I have gotten woods on so tight I had trouble backing it off the wormwood screw... I have one of those belt type wrenches similar to what is used to remove oil filters that I've had to use to take the bowl off the screw. And once I even had to take a pair of channel locks to the screw to back it out. I no longer have the strength in my hands to get tight enough grip on the blanks to turn them by hand.

I like to start a bowl on the faceplate, but always use machine screws - NOW - after I put a piece of Bartlett Pear on a 6" face plate with 6 #6 screws... first catch sheared all 6 screws and threw the blank at me.. when I ducked it went through the door of the shop... right after that I made two definite changes... no more sheet rock screws and got rid of the Ridgid lathe...slowest speed on that was 750 and that's twice the speed I should start an out of balance and larger bowl blank.

I like to do a recessed inside chuck on most bowls... I just like the way they sit when finished.... unless I'm doing a footed bowl, then sometimes I'll use an external tenon. Either way, I almost always concave the bottom slightly to make sure it sits squarely.
 
Chuck,

Try puttin some wax on your woodworm screw before inserting it. I too prefer a recess in the bottom. Once I have finished the inside and outside, I flip it back around and use a friction drive to hold it against the tailstock and finish off the bottom with anything I want.
 
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I don't like to chuck from the inside. It's amazing how often the chuck pressure reveals a hidden flaw in the bowl - usually one it creates in the first place. I've yet to have a bowl tenon shatter from outside pressure. Of course, I just slap the bowl on a vacuum chuck once it's time to finish the bottom. It is fairly easy, though, to make a large chuck that grips the rim from the outside.

Marc
 
ozmandus said:
This works most of the time, and If you are doing a small mouthed opening in the bowl, almost a must.... but I have gotten woods on so tight I had trouble backing it off the wormwood screw... I have one of those belt type wrenches similar to what is used to remove oil filters that I've had to use to take the bowl off the screw. And once I even had to take a pair of channel locks to the screw to back it out. I no longer have the strength in my hands to get tight enough grip on the blanks to turn them by hand.

I like to start a bowl on the faceplate, but always use machine screws - NOW - after I put a piece of Bartlett Pear on a 6" face plate with 6 #6 screws... first catch sheared all 6 screws and threw the blank at me.. when I ducked it went through the door of the shop... right after that I made two definite changes... no more sheet rock screws and got rid of the Ridgid lathe...slowest speed on that was 750 and that's twice the speed I should start an out of balance and larger bowl blank.

I like to do a recessed inside chuck on most bowls... I just like the way they sit when finished.... unless I'm doing a footed bowl, then sometimes I'll use an external tenon. Either way, I almost always concave the bottom slightly to make sure it sits squarely.
Click to expand...

Chuck I turned one last night using the wood worm and I couldn't get it unscrewed.( I have chronic immflamation in the tendon of my right wrist so my grip ain't it's best and yes I make it a habit to wear a wrist splint anytime I turn..:wink:. Anyway I had to put the key in the chuck and rest it on top of my tool rest, get a two handed grip on the pices and it came right off. But all in all I was impressed with the way the WoodWorm held the piece while turning!
 
marcruby said:
I don't like to chuck from the inside. It's amazing how often the chuck pressure reveals a hidden flaw in the bowl - usually one it creates in the first place. I've yet to have a bowl tenon shatter from outside pressure.
Click to expand...


We seem to be opposites. :wink:

I haven't had a bowl shatter from outside pressure, but far in the past, I've had small parts of the tenon break off, and the bowl let loose. My turning skills were much worse then, so it was probably due to my being too aggressive or having catches.

In any event, I switched to chucking from the inside, and have never had a failure or problem with it. Now that my skills are better, I could probably go back to chucking from the outside... but I just like the inside better.

To add fuel to the drywall screw fire, i just turned a natural edge bowl from Box Elder burl. I took the flat part of the burl, glued it to a waste block, and turned a depression in the natural edge for my 2" aluminum faceplate, then sawed off the glue block and screwed in the faceplate. All I had handy were some drywall screws.

The block was sufficiently off-balance to give my lathe and stand a GOOD shaking, but still, no drywall screws bent or broken.
 
Lets look at some screw basics; there are several factors at play here. The screw has a minor diameter (the diameter at the root of the thread) and a major diameter (the diameter at the tips of the threads). The difference divided by two (for the two sides) is the depth of the thread.
Wood screws were developed to hold wood with long screws gripping deep into the wood, the thread depths did not need to be large since the hold came from long screws.
When we are woodturning we try to keep the screws short to use as much of the blank as possible. The typical wood screw does not work well in this application. Sheet metal screws with deeper thread depth are a better choice. Another good choice is a low root or particle board screw. These have a deeper thread depth than sheet metal screws. These screws are not easy to find which is hard to believe with so much particle board furniture used today.
Dry wall screws do have a deep thread depth, but they are highly hardened which tends to make the screws very brittle. They are strong, but snap easily if over torqued or subjected to shock or repetitive loads - all occur on a lathe application.
Another factor to consider is to minimize the damage to the wood when driving the screw. The wood tends to be damaged as the thread is formed into the wood. Drilling a pilot hole will reduce the damage and improve the hold strength. The pilot should be slightly smaller than the screw minor diameter.
Also consider increasing the number of screws used. I drill my face plates with additional holes. I have held large blanks with short #6 screws, but I used many screws to ensure a strong hold.
I hope this helps, just wanted to share some things I learned when I worked with wood in the furniture industry.
 
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