A drawing (of sorts) of the other idea. Make the plates, drill tap etc and put a hole in the middle of each. If your not confident of the accuracy of the plate, make a mandrel, bit of bar faced off, drill and tap centre and bolt (counter sunk) on each plate in turn and very gently face off all 4 surfaces so chuck will be dead parallel to face of table?? Apologies for the crude scribble! I have no idea of your skill on the lathe or your.. if you're like me, incredible scrounging skills and alergic to buying things when you can spend 6 months making one! But just to add, 120 deg holes are very easy. Again, 3 jaw chuck and mandrel you just made with a plate bolted to it through the centre in lathe, get a bit of scrap bar (or a snapped off pencil) that just fits between a flat conveinient surface like the bench and the chuck (lathe) jaw. Turn the lathe off! Hold the jaw down on the scrap so its wedged between jaw and bench and using the crossslide and a sharp turning tool, scribe a line with the lathe tool. Turn the chuck till the next jaw rests on the scrap, hold and scibe again, then do again with the final jaw = 3 x very accurate lines at 120 degress apart. Decide where the bolt centres will be, set the lathe tool to the right diameter (PCD) and rotate the chuck by hand marking the hole centres?
Hope this is of some help.
Tom, Thanks for those thoughts. I have a feeling there's not enough clearance between table and locking arm etc. to do that but I'll go measure over the weekend. the pictures were fine, as they say, worth a 1000 words! I've seen works of art such as these decribed as CoC elsewhere on the web... CoC = "Crap O' CAD" :heehee:, works for me!
CoC... like it!Sherline lathe, Chester DB11V lathe, Myford/ Rodney mill, CNC mill Isel/ home made, Sealy Hack Saw, Meddings Pillar drill.
I'll try to explain the drawing above.
One back plate screwed to rear of chuck. studs and grub screws to match the number of Tee slots.
The grub screw fit into tapped holes in the side and need a taper on them.
The studs have a matching tapered hole BUT it's drill slightly lower than the centre of the grub screw hole.
The idea is that as you tighten to grub screw up it pulls the backplate and table together.
Nice thing about this is that it's not size related to the table. You could fit an 8" chuck to a 6" table using this method.John S -
Don't get trapped in 2D. Bolts can go through a backplate and still be accessable from the side. All you need is one Allen key clearance :naughty:
Those pictures were really helpful in concreting JohnS' thinking. That doesnt look so hard to make either, though how do you make a small (say 5mm dia max) tapered hole. A 3 - 14mm HSS taper drill is about a tenner on Amazon (although these are supposedly only for drilling sheet). Machining a taper on a bit of 6mm silver steel rod shouldnt be hard - tho I'd imagine these might need hardening after?. The T-slot in the table is 6mm wide I think, so some 12mm silver steel rod would do for the pins (again do I need to harden after)? Then I need a 100mm cast iron plain backplate, or a 12mm thick bit of 100mm dia mild steel?? I suppose it has to be steel?
Wish i had joined earlier.
I have had a 5 1/4" 3 jaw on a vertex 8" rotary table with 4 slots for 11 years. Its done a lot of work.
Take chuck apart and you will find an area you can drill straight through. I used 6 M5 cap heads going in to self made T slot nut, 4 or 5 direct in to table tapped M5.
Did originally make a boss to centralise the chuck in to MT3 taper but would easilly go out of true.
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