craftex lathe chuck conversion

[hobby job]

Hi Everyone.
I'm new to this forum and new to mini laths and metal work. I have a craftex mini lath 7"x8". It works great but I want to fit an adjustable 4 jaw chuck to it. Has anyone done this and is there already a conversion kit available for this machine. I guess it should have a plate which interfaces between the lathe plate and the chuck.
Any help would be appreciated.

[Hillfrog]

I do not know if I can l help as I do not know your machine.
If there is no specially made chuck then usually lathe chucks have a back plate. These can be bought usually from the lathe maker or specialist suppliers. This is a dedicated disk that has a fitting (usually a large internal thread) that matches the nose on the lathe spindle. You fit this to the lathe spindle and turn this to be true on the face and turn down a step to be the best fit you can get into a chamber in the back of the chuck. What you are doing is making a register.
You say adjustable chuck. Do you mean a four jaw independent chuck?
If so it probably has four holes that are counter-bored to take four socket head screws. (You might find these called Allen screws). The back plate is drilled and tapped to accept these. The back plate is then attached to the chuck tightening these screws firmly and then the chuck is ready for use.
Beware that centring a four jaw independent chuck may require using a Dial Test Indicator (DTI or might be called a clock or clock gauge) mounted conveniently on a magnetic stand. I have had students in tears trying to centre work. It is an easy trick to learn by adjusting two opposing jaws together to shift the work in line with the DTI half the error indicated on that jaw pair.
What you must not do is set something way off centre or out of balance and then try to start up at speed. The entire lathe will jump about violently. With a large machine it will be the last thing you do as large machines have a habit of eliminating idiots. Run slowly and increase speed until vibration starts and then run below this speed.
You can find what I mean by a four jaw chuck in Wikipedia and on the web, “fitting lathe chucks” (metalwebnews.org/mr-tools/lathe-chucks.pdf) shows an old but valid method of fitting a chuck back plate.

[Crevice Reamer]

The Craftex 7 x 8 appears to be a close cousin to the Harbor Freight 7 x 10 mini lathe. If this is indeed the case, then both 4 jaw chucks and adaptors are available from Little Machine Shop:

http://littlemachineshop.com/product...t=lathe+chucks

CR.

[basalt]

Hi,
I have the same lathe. I bought a 3.188 Dia. 4 jaw from Busy Bee machine tools. The number stamped on the back is 1305. It was for a rotary table. Cost about $80 c/w alum. adapter plate. The counterbore Dia. is only about 0.003" smaller than the spigot on the spindle and the bolt circle diameter is the same. It has 4 studs which would require drilling 3 extra holes in spindle plate or you could modify the adapter plate. Hope this helps.
Good Luck,
Basalt