Thread: Lathe D1-3 Camlock Studs

Purchased a 14.5 mm drill, drilled out the backplate, achieved 24 mm scallop protrusion with one turn of the camlock stud available for future wear and stretch.
Cleaned off all machining burrs, checked/corrected any blemishes.
Mounted on the spindle, the cams tightened up midway between the two marked limits - job done.

Now to fit the ER32 chuck.
Mounted a cast iron puck in the 4-jaw and machined a shoulder matching that of the backplate as a learning exercise of chuck fitting.
The only measurement instrument available was my 35 year old Mitotoyo vernier caliper so size was approached carefully.
Found it difficult to offer up the chuck squarely to check size with the result that the final fit risked being loose.
Overcame the squareness problem by mounting a length of Dia 19 bar in the collet chuck and holding the outer end in a tailstock drill chuck - see photo below.
When chuck offered up to the puck, it slipped on, indicating a little loose.
ER32 Chuck 1 compr.JPG

Mounted the backplate and proceeded to machine the shoulder for the chuck.
Made the engagement length 5 mm and put a 1 mm lead chamfer at 10 degrees.
The CI machined beautifully, better then the puck from the TAFE scrap bin.
The final fit needed a push from the tailstock, tapped home with a dead-blow rubber mallet, and pulled tight with the capscrews.

A length of Dia 19 ground bar mounted tight in the chuck gave a TIR of 5 div on the 0.0001"/div dial indicator.

Not as good as I hoped, so removed bar and checked the chuck taper; front is TIR 2, middle 1 and rear <1.
The chuck OD is TIR 1/2 div, and the front face 5.
The values may be indicating some out-of-squareness.
Interestingly, the diameter behind the nut mounting thread is TIR 32, over 3 thou !

I will leave alone and use it for a couple of jobs, then consider if worth trying to correct.

John

Hi John,

Not much help now but I had the same issue with my flange mount ER32, after making an adapter plate I had to grind the taper in the chuck.

Stuart

Thanks Stuart,
I will consider whether to grind or not after I have used the chuck a few times.

Unknown is whether the TIR of 5 div on the front surface is due to incorrect mounting, or the result of the factory decorative grind being slightly out-of-alignment with the mounting features at the back.
If there was only one grind setup to do the decorative finish and the chuck taper, the measured TIR reflects either a bad grind or a bad mount.
I would have to dismount the chuck to sort it out - a last resort.

The front/back relationship will be checked on future mounts, planned to be a small 4-jaw chuck and then a 5C collet chuck, easy with a good micrometer.
An attempt will also be made to see if one can assess concentricity and squareness of the jaws/taper to the mounting features using a surface plate, test bar, V-blocks and test indicator.

Dismounting has its own problems, there are two threaded holes in the backplate assumed to be provided for jacking the parts apart, but one of them aligns with a clearance hole in the chuck.
I will ensure the next items have threaded holes for jacking available and useable, or add them if necessary.

A final consideration is the amount of parallel engagement used, I machined in 4 mm.
The D1-3 spindle mount is only about 2.5 mm, perhaps this smaller value is what I should have used.
Time to do some web searching.

Happy machining,
John