Safe Drivers

[crokett™]

A while ago (I think about a year) I was looking for a way to hold larger bowl blanks for roughing that didn't cause the lathe to wobble when a face plate is used on an out of balance blank.  I got a suggestion for a safe driver - example is here:  Safe Drivers (oneway.ca). Due to work, my inlaws health, my daughter's theater group and just life in general a lot of that fell to the bottom of a very long list.  I was rereading that thread last week and was looking over what live centers, etc I have.    I have something very similar to the oneway, except the tip isn't spring loaded.  Does it have to be?  Can I still use it as a safe driver?  I may combine the safe driver with MM's method of a pin jaw chuck in a shallow mortise.  That would still allow for finding the balance point (within reason) while making me feel a little safer than just using a cone live center.

[briman87]

I have used a steb center also called crown drive as a safe drive. I have used this for turning inside out ornaments. https://www.woodturnerscatalog.com/p/107...ive-Center.

[greenacres2]

The Robust cup center that I use is not spring loaded and works great. In use, seems like the spring would not be relevant once the cup is seated. Only advantage I can think of is in positioning the work piece initially, but I could be wrong. I used Stebs for several years, but rarely since getting my first cup center. Very rarely, like in I should sell (but won’t…just because!!)
Earl

[crokett™]

I have a steb center. I may try it also. It is not my favorite to use but I guess it reinforces good turning technique since if you are too heavy handed or your tool is dull it slips.
. I use it mostly for smaller diameter spindles.

[SceneryMaker]

I have 2 different cup centers that I use as safety drive centers when starting a newbie out. Neither one has a spring point in it. Either one would work nicely to help find the best axis for turning.

A novice can jam a gouge into the work and try to promote a catch but they just slip. These centers are a great way to teach tool control, especially if you don't clamp the tailstock down to war emergency squeeze.

[MKepke]

I don't see how one of these spur-type 'safe drivers' helps with an out of round bowl blank. My gut says a typical sized spur drive like a Stebcenter is going to slip in a heavy, green, out of flat surface bowl blank. That's the opposite of a safety feature in my book (when the spur drive chews enough of a hole to allow the blank to slip).

What you need (I think) is a system that allows you to properly balance the bowl blank, then securely drive it that balanced state.

I'm sure some oversized spur drives would work, like the Texas Spur - but the price? Ouch. https://bestwoodtools.stores.yahoo.net/tespdrce1.html

I use a somewhat crude DIY solution consisting of a 5" faceplate threaded for 5/16" x 2" bolts. The bolts are sharpened on the ends so I can drive them deep into the blank.

I balance the blank using trial and error. I don't set the bolts deep until I'm satisfied the blank is balanced.

Here's the commercial version. I think mine is better because it doesn't rely on a Morse taper, it screws onto the spindle.

https://woodturningtoolstore.com/product...drive-2-5/

Largest blanks I've use mine with were 20" and probably 50-60#. (Note I always turn with the tailstock in place until the piece is almost fully roughed out).

-Mark

[EightFingers]

I just stay home on New Year’s eve….

[crokett™]

I don't see how one of these spur-type 'safe drivers' helps with an out of round bowl blank.  

The safe drivers  don't have spurs.  That's the point.   If you are poor at handling a tool or you are cutting with a dull tool, the part will slip if there is a catch, rather than be flung off the lathe.  For an out of round bowl blank, having something that heavy fly off the lathe is dangerous.  You combine the safe driver with the method to find the balance point of an out of round blank and then you get something that is at least a little safer. 

A steb center is something different than a safe driver.  I have one, but only really use it on smaller diameter spindles.

[MKepke]

The safe drivers  don't have spurs.  That's the point.   If you are poor at handling a tool or you are cutting with a dull tool, the part will slip if there is a catch, rather than be flung off the lathe.  For an out of round bowl blank, having something that heavy fly off the lathe is dangerous.  You combine the safe driver with the method to find the balance point of an out of round blank and then you get something that is at least a little safer. 

A steb center is something different than a safe driver.  I have one, but only really use it on smaller diameter spindles.

Sorry, calling them all "spur" drives was a bad word choice on my part. How about "sawtoothed cup drive centers".

And yes, the Stebcenter is marketed as a safe driver along with a number of other similar sawtoothed cup drive centers.

That said, I feel like we're getting off topic here: your original post was about " a way to hold larger bowl blanks for roughing .. on an out of balance blank".

Are you having a problem with catches or do you just want to securely drive large out of balance bowl blanks?

-Mark

[SceneryMaker]

Is it possible that he is looking for a pointy drive center that he can easily move around to find the best axis for turning like Lyle Jameson frequently does?