Worm screw vs face plate

[Dave Landers]

I did a search on the forums and couldn't find any info, so here's my question. How does one decide to use a worm screw or a face plate?

I would say that a worm screw is mostly convenience - drill one hole and thread it on. A faceplate requires several screws and generally a larger flat area. As may be mostly obvious, several screws vs one should normally be "better".

I've just started and can't afford a proper woodturners chuck right now so am using an old metalturners 3 jaw chuck.
...
I start mostly between centers but am trying to enhance my own safety as well as develop a variety of techniques.

For that safety enhancement thing, I'd stay away from the metalworker chuck - the jaws just aren't designed to grip wood effectively. Not enough contact.

Lots of bowls were turned before woodturners chucks became available.

One common technique was to screw a faceplate to the bottom of the bowl blank - and then deal with screw holes when it's finished Or waste a lot of wood at the base so you can avoid the screw holes Wasn't uncommon to see bowls with green felt glued to the bottom to hide the holes

If I were to turn a bowl today with just a faceplate (or worm screw): I'd start with the faceplate attached in the mouth of the bowl (so screw holes will be turned away). Turn and sand the outside shape and then true up the bottom.
Have a waste block of wood with a faceplate attached (or with holes drilled to attach your only faceplate). I used to buy chunks of 2" thick poplar at the home despot for things like this, before I had a reasonable supply of scraps.
Glue the waste block on the bowl bottom, using the tailstock to align and clamp it (wood glue would be my preference if the wood is dry enough*). Let the glue do its thing and reattach the faceplate.
Should be able to now mount the bowl and turn the inside. If the bottom-truing/waste block/faceplate step was done with care, it should run pretty true.
Do what you can with the tailstock engaged for safety (you can't get very far inside a bowl that way, but every moment of extra support is worth it).
Then part off the waste block and deal with the bowl bottom.
Because I like a turned foot on the bottom of my bowls, I'd now turn it around between centers with a padded waste block in the inside of the bowl. That'll get me access to most of the bottom. Then finish the nub where the live center was using a chisel or pocket knife or sander or etc.

That's a lot of flipping stuff around and waiting for glue to dry etc. Which is why most of us turners bought a chuck as soon as we could afford to. But since the chuck really only saves you time and effort, it could be categorized as a luxury (I thought of my first chuck that way).
There is a distinct advantage to learning different ways of holding stuff on the lathe. Working without a chuck forces you to get some of those skills in your mental toolbox.

* If the wood is still wet, wood glue might not be a good choice for attaching the waste block. CA glue does ok against wet wood, but can be brittle and a catch might break it free, so easy does it. Gorilla glue (polyurethane) would probably be great, as it's moisture activated anyway. Other choices might include hot glue, good quality double-sided tape (not cheap carpet tape), epoxy... each has their strengths and limitations.

 

[Bill Blasic]

That is a good link Doug. I got down in the shop yesterday and got 1 of the two pieces I owe done and hope to go down today and finish the other. I cannot believe how much I have lost between a bad back and sciatica for 5 or 6 months and then low blood pressure. I could only stand at the lathe for a few minutes at a time and I'm so shaky. I've also lost 60 lbs. My back was pretty sore. I'm going to get on the stationary bike and build up my legs. Now as far as that link for David Morris, look at that link and in the first section you will see NCK - 4" That's a 4" Tommy Bar chuck about the same size as a Nova Tommy Bar chuck for $52.99 (if your lathe has a 1" X 8 spindle). There is nothing wrong with a TB chuck when you get used to using them they are way faster than screw to tighten chucks and hold just as well if not better. It would be better than the machinist chuck you are using and it takes a good selection of the other jaws. Once you get above the 4" TB chuck the prices go up steeply compared to the others. I'm going to keep an eye on the 2 3/4" chuck to see what it costs as I like these very small chucks. As far as the $69 good value chuck you asked about I still have not used it and all I can say is that it looks and operates very well but as yet I haven't used it.

 

[John K Jordan]

Other choices might include..., good quality double-sided tape (not cheap carpet tape),

Double-sided tape used to be a very common technique for holding, the method taught to a friend 40 years ago. He uses the good "woodturners" double-sided tape, available from Woodcraft and elsewhere. (As Dave mentioned, do no use carpet tape.)

His old lathe had an reeves drive that didn't work well so I gave him a Jet 1642 and some dry blanks and a couple of days later he brought me this bowl, his first turning in many years, about 12" in diameter.


PM 2025

He starts by mounting the top to a face plate. Turns round and shapes the outside and flattens the bottom. Removes the bowl and fastens the base to the faceplate with the double-sided tape and applies pressure. Then turns the inside.

The tape holds so well the problem is removing the wood from the faceplate. He generally injects acetone into the tape with a needle and syringe. When we use the tape for holding metals for machining, driving a thin wedge will separate the parts nicely (but very slowly!) Turned some much larger bowls outboard using this method.

I gave him some chucks so we may have a chuck lesson soon.

JKJ

 

[John Grace]

More information would be nice for those concerned. Some questions come to mind.

• Brand and type - high quality machined screw in a screw chuck or "wormwood screw" that came with a scroll chuck. Wood screw/lag screew?
• Type, size of blank.
• Hole diameter and depth
• Species of wood - solid, cracks, punky?
• Was the mounting face flat?
• Wood blank in face (cross grain) or end grain?
• Mode of failure - broken screw, screw separated from the wood, wood failure, other?.
• Supported with tailstock?
• At any particular speed?
• Was there a catch or some other irregularity involved?

I know a lot of people who use screw chucks and wormwood screws and haven't heard of one failing.

Teknatool
6" and two 10"
Deeper than the screw and just big enough for the screw to 'bite'
Walnut, ash, and maple (all solid without defects)
yes
cross grain
screw stripped out
supported until I needed to get to the 'other side' of the blank
all less than 700rpms
no catches

I now have a sound assortment of face plates and the proper screws...never EVER going back to worm screws as there's no need.

thanks...john

 

[John K Jordan]

I now have a sound assortment of face plates and the proper screws...never EVER going back to worm screws as there's no need.

That makes sense. I wondered if the screws were Teknatool/Novas. Breaking without provocation (side stress, overtightening, etc. is troubling - I'd think I would have sent them to Teknatool, especially since three broke.

When you said the screw "stripped out" do you mean the threads broke off the screw leaving a round shaft?

I have a bunch of the Nova wormwood screws since one came with every chuck. I don't like the way some of them look and and don't plan ever use one. Some look so bad I'm not really surprised to hear of problems. Some look like they were sand castings from mystery metal. Even the threads were rounded instead of sharp which seem like they would take a lot of force to . (After hearing your story I want to test the breaking strength on few with a hydraulic press or put some in a vise and see if they'll break with a hammer. The screws I've seen from other chuck makers looked better.

However, for my procedure turning a variety of face/cross grain pieces a single screw has many advantages including simplicity and efficiency. My method works so well for me I call it a "need." I'll stick to the Glaser screw chuck with the precision machined screw. I know several others who bought the Glaser after I demonstrated.

I have a couple of student/friends who work like I do (no surprise since that's the way they were taught!) and gave them the screws when I gave them Nova chucks but said I didn't trust them. I sent them on their way with Glaser screw chucks and said please use these instead!

JKJ

 

[Kevin Jenness]

Lyle Jamieson shows how and why he uses faceplates and glue blocks rather than chucks. Not for everyone, but he has reasons. The CA glue he uses is fast-setting, sticks to wet wood, and can be split off when done with a chisel. You can use Gorilla Glue for wet wood or pva for dry blanks if you want a less brittle bond and can wait for the cure. I think it's the way to go for weak or punky blanks with poor screw-holding that would be crushed by chuck jaws,