Homemade screw chuck

[Random Orbital Bob]

For any who followed the apple turning thread I wanted to just report a couple of helpful pointers that made an enormous difference to a home made screw chuck I made today.

In the struggle to perfect the apple technique I threw out a poorly made screw chuck as unfit for purpose. I was really struggling to get the screw to run true after it was installed despite being ultra careful with the Jacobs chuck pilot hole boring operation. Had a brew and scratched the head, googled about a bit and found some guy who puts his Jacobs chuck in the headstock morse taper and grips the screw. This allows you to re-turn the spigot on the back of the screw chuck which will now be perfectly centred on the screw since that's now in the axis of the spindle. So I did this, being careful to avoid the Jacobs chuck working out of the spindle by locking it with the side of the toolrest, and then reversed it again in the now true spigot and re-faced off the front which had the screw poking out of it.

The advice was to make the face ever so slightly concave which I did. Once done, I brought up the tailstock centre to check it for runout and it was better than my commercially made screw chuck. So the Jacobs chuck in the headstock step really solved the poor runout problem.

I also used a longer screw than the one I made yesterday because the dimple in the apples is actually quite deep and that took up so much of my screw protrusion that precious little was left to grip the work.

I also turned down a lot of the wood on the face so it leaves room to get access to any details you might want to on any future piece of work.

All in all a vast improvement on my first screw chucks which had major design flaws. This is purpose designed for fruit. Thought it worth reporting to the folks who are on the apple trail in case you bump into the same technical difficulties I found
Didn't take any photos, sorry.

 

[Grahamshed]

Didn't take any photos, sorry.

Thats not good enough Bob. When you get off the naughty step throw the chuck away and start again.

 

[gregmcateer]

Thanks for that, Bob. Any chance of a photo of the finished chuck, poss with a ruler near it?
TIA
Greg

 

[Random Orbital Bob]

LOL...Graham, you do put a smile on my face when I read your posts

Yeah sorry boys, I know its not up to the usual standard, trouble is I'm off to Cambridge for a 60th all weekend too so no chance to do anything. I'll get on it next week. Can I come off the naughty step now please? Or as my son says after being sent to his room, about once every 3 seconds....can I come out now, can I come out now, can I come out now, can I come out now

 

[Grahamshed]

So, from near Reading to Cambridge.
Are we nearly there yet ?
Are we nearly there yet ?
Are we nearly there yet ?
Are we nearly there yet ?

 

[jpt]

Here is my method as described by Bob http://www.woodturned.co.uk/html/screw_chuck.html

Richard Findley was the one who mentioned to me some time ago about holding the screw in a Jacobs chuck and re-cutting the chucking point to make sure it runs square.

john

 

[Spindle]

Hi

I can't remember the last time I used a screw chuck - glue chucks have totally superseded them for me.

Regards Mick

 

[Random Orbital Bob]

Yeah but Mick, you can't use a glue chuck with a turned fruit because its the parting off you're trying to avoid.

 

[Random Orbital Bob]

Here is my method as described by Bob http://www.woodturned.co.uk/html/screw_chuck.html

Richard Findley was the one who mentioned to me some time ago about holding the screw in a Jacobs chuck and re-cutting the chucking point to make sure it runs square.

john

That's funny John. Where I referred in my original post to surfing the web after stopping for a brew and finding the solution...it was your BLOG that I found

So thanks for that, I get to credit you properly now (and Richard again I guess one generation earlier).

Now, one last question. I've ordered some ebony with intended use being the stems. Any tips on holding methods for very very thin stock? I will bandsaw the ebony into thin square blanks and then plan to batch turn a few at a time ready for apples and pears. Just wondering what work holding method you use for stock that's only say 5x5mm square? Pin jaws I guess? Anything else?

 

[Richard Findley]

Hi Bob

Glad my methods are helping you :wink: , I used to hold the stalks in my Jacobs chuck in the headstock, but since having the Wadkin - which has a solid headstock - I use engineer type stepped jaws a lot in my Axminster chuck.

HTH

Richard

 

[Random Orbital Bob]

Thanks again Richard.

 

[Random Orbital Bob]

Thanks for that, Bob. Any chance of a photo of the finished chuck, poss with a ruler near it?
TIA
Greg

Hi Greg, apologies for the late response.....60th birthday party all weekend for my brother.

Here's some snaps taken this afternoon

P = protrusion of the screw from the face of the chuck. diameter of the screw is 5mm. The other screw chuck shows the kitchen sponge I used to cushion it which I didn't do on the other one and it didn't dent an apple I turned.