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Post by Pete on Jun 13, 2019 20:45:53 GMT
Curiosity go the better of me and I have obtained a Robert Sorby Wobble Chuck, I am sure you have all seen the YouTube demo of it, if not it's here Well I wanted to go bigger and turn this  into this  See the PDF for my review and some more photographs. Robert Sorby Wobble Chuck review.pdf (523.09 KB) Conclusion, the Wobble Chuck is a fun addition to your toolset, gives design opportunities that can stretch your imagination. I will use it some more. |
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Post by Pete on Jun 16, 2019 4:20:00 GMT
Oops, realized guests can't see PDF attachments, so I will try to reproduce it here, but can only add 3 of the photo's. Robert Sorby Wobble Chuck reviewSo after watching YouTube, and being fascinated, I gave in and got a wobble chuck, obviously the first thing I did was chuck a bit of small stock on it and copy the official video on YouTube, and basically make a crankshaft.
But I wanted to do something a little bigger to try it out properly, and decided on a lamp.
 This is the Wobble Chuck disassembled, it is basically a cam'ed faceplate with a screw in screw fixing all locked in various positions with grub screws.
This being a test of the chuck rather than an actual target end piece I just grabbed a log, squared it off on the bandsaw as I actually wanted a square base then using my home made long hole boring tool cut a top, bottom, and drilled it ready for the cable.
I actually roughed it into a starting shape before mounting it on the wobble chuck, but forgot to photograph that! This is it on the wobble chuck but before I turned the lathe on! So it is my start point. Importantly I drilled a small 25mm recess about 2mm deep for the lamp holding plate in the top.
I needed to be aware that I had a 10mm centre hole for the lamp cable so couldn’t cut through to deep, despite this being a fairly large piece of wood the small faceplate which was actually inset into the base in the section that would end up as my turning space for the power cable. And the 3 screws held very well.
I loosened the grub screws on the chuck and put it off centre so that my tailstock was at one point up against the side of the 25mm depression I had made. When I wanted to off centre in the other direction I used the other side giving me 3 easy reference points.
Then I span it up SLOWLY! Everything was fine, I soon gained confidence and sped it up to around 600rpm before taking my 12mm spindle gouge and basically cutting a cove, obviously there is a lot of free air time so you need to be attentive but once you start cutting looking at the ghost image over the top of the piece as normal gave a good indication of progress. However there is a need to stop and check progress a bit more often than normal.
I marked up the shaft in 30mm sections reversing the wobble chuck on each section. Normally I would put an oversize ball at the base to aid with stability, but got carried away and wanted to see what the wobble chuck would do on the pre-ball ovoid so this one ended up with 2 doughnuts on the bottom!
Sanding and possible first level of finish should be done on each section as you go, though you can get near enough back to the same offset using the 3 marks I set up it’s only near enough!
Overall I am very impressed this was a 100mm x 100mm block about 350mm long held on a 3 screw mini faceplate and run deliberately out of balance, yes the tailstock helped hold it all together, and I did cut it chunkier than normal to give me lots of wiggle room if it all went wrong… but it didn’t it all worked exceptionally well and gave an interesting repeatable effect.
Only problem was, once I had added a bit of oil screwed on the top plate, and threaded the cable through the lamp, I discovered I don’t have any lamp holders!
In conclusion, yes I recommend the Robert Sorby Wobble chuck, it is a fun addition to your toolset, I think I would follow the same basic steps again, i.e.
1. Get a basic lamp cored and balanced in a rough shape.
2. Do the top and bottom of the lamp so they are true and parallel
3. Then mount on the wobble chuck in central position and be sure everything is still in balance
Then I think I would probably use the centre position of the wobble chuck more, and just have 2 or 3 off centre sections where I would take it a lot closer to that 10mm central hole, maybe!
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into this 
