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Prompted by the reply I made to Baddog about fitting chucks to RT's as I went away working I realised that this is a very common question and one that I have never seen a satisfactory answer.
One answer is to fit the chuck to a backplate and mount the backplate using tee nuts and the Tee slot. This is fine if your chuck is smaller than the RT.
Next idea is to use front mounting chucks and drill and tap into the backplate or table.
Disadvantages of this method are that front mounted 3 jaws chucks are quite rare and often people won't drill and tap the table.
The real problem arises when the chuck is the same size as the RT or even bigger and the only two ways are to use front mounting chucks again or remove the table, drill thru from the back and reassemble which is a bit of a balls ache if you need to keep swapping over.
As I was working I gave this some though, knocked off, had a coffee and built a mock up.
Although it's a mock up it does work and function correctly.
Basically imagine that alloy block as a circular backplate that you can screw your chuck to either from underneath with counterbored cap screws or thru mounts if you are so lucky.
Now that block has three holes [ or 4 ] that match the tee slots on the RT. You then drill a tapping sized drill hole from the side to meet the vertical hole, don't tap at this point.
Next job is to machine 3 [ or 4 ] circular tee nuts as in the last photo and flat two side to sides [ actually thinking about this as I type that's not even needed, you can leave them circular but they have ] to fit the slot.
Number the tee nuts and holes. Then fit the tee nuts to the slots, drop the plate on and using a screwdriver or wedge raise the tee nuts up. Spot thru the side hole to LIGHTLY mark the tee nuts.
Strip and remove the tee nuts and about 1/32" LOWER down from the mark drill a hole same as the tapping drill size.
Last machining job is to tap the side holes in the backplate and get three allen grub screws and machine a 10 degree taper, [5 degree set over on the top slide ] to blend in.
To assemble, fit the chuck to the backplate, slide the tee nuts into the slots and drop the backplate over the tee nuts, get the number right.
Then fit the allen screws and tighten in turn a bit at a time.The wedging action of the screws will draw the tee nuts and the backplate firmly down to the table.
This block is very firmly fixed and a decent tap with a hammer won't move it.
With a spigot it will be a very secure method of fastening but also quick to swap over.
It's also possible to use this method to fit an 8" chuck to a 6" table, cleanly, neatly and firmly.
Oh BTW this is now under the El Stevo International Patent rights
.
One answer is to fit the chuck to a backplate and mount the backplate using tee nuts and the Tee slot. This is fine if your chuck is smaller than the RT.
Next idea is to use front mounting chucks and drill and tap into the backplate or table.
Disadvantages of this method are that front mounted 3 jaws chucks are quite rare and often people won't drill and tap the table.
The real problem arises when the chuck is the same size as the RT or even bigger and the only two ways are to use front mounting chucks again or remove the table, drill thru from the back and reassemble which is a bit of a balls ache if you need to keep swapping over.
As I was working I gave this some though, knocked off, had a coffee and built a mock up.
Although it's a mock up it does work and function correctly.
Basically imagine that alloy block as a circular backplate that you can screw your chuck to either from underneath with counterbored cap screws or thru mounts if you are so lucky.
Now that block has three holes [ or 4 ] that match the tee slots on the RT. You then drill a tapping sized drill hole from the side to meet the vertical hole, don't tap at this point.
Next job is to machine 3 [ or 4 ] circular tee nuts as in the last photo and flat two side to sides [ actually thinking about this as I type that's not even needed, you can leave them circular but they have ] to fit the slot.
Number the tee nuts and holes. Then fit the tee nuts to the slots, drop the plate on and using a screwdriver or wedge raise the tee nuts up. Spot thru the side hole to LIGHTLY mark the tee nuts.
Strip and remove the tee nuts and about 1/32" LOWER down from the mark drill a hole same as the tapping drill size.
Last machining job is to tap the side holes in the backplate and get three allen grub screws and machine a 10 degree taper, [5 degree set over on the top slide ] to blend in.
To assemble, fit the chuck to the backplate, slide the tee nuts into the slots and drop the backplate over the tee nuts, get the number right.
Then fit the allen screws and tighten in turn a bit at a time.The wedging action of the screws will draw the tee nuts and the backplate firmly down to the table.
This block is very firmly fixed and a decent tap with a hammer won't move it.
With a spigot it will be a very secure method of fastening but also quick to swap over.
It's also possible to use this method to fit an 8" chuck to a 6" table, cleanly, neatly and firmly.
Oh BTW this is now under the El Stevo International Patent rights
.
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