Building a back plate for my 4-jaw chuck
Difficulty Level (Easy, Medium, Hard, Insane):
Medium
Process:
When I got my metal lathe it unfortunately didn't come with a 4-jaw chuck which is fine for most jobs but any time a job requires an off-center or square piece of stock, a 4-jaw chuck makes life a lot easier.
I ended up buying a cheap-o chinese 4-jaw chuck at Busy Bee Tools but still had to mount it on my lathe. Luckily, I bought a bunch of metal blanks at one of the auctions I went to recently. However, since this was one of my earliest projects it took me forever to do and when I finally finished I realized that my digital calipers had unfortunately zeroed out at 4 thousands instead of 0 which meant that the final size of the alignment rim was 0.004" over sized.
I thought maybe I could make it work, but because it was the base for the chuck on which all other work would be turned I realized that it was not going to be accurate so unfortunately I had to start the project all over again.
The second attempt went a lot faster but it still took me about 5 hours to do and just when I was getting ready to do the final cut, being very careful the calipers were zeroed properly I mis-calculated my adjustment and bored the center alignment hole 20 frickin thousands over!!! I was so mad!
So I started the 3rd attempt. It went faster than the first two and probably cranked out the part in about 3 and a half hours and this time it was perfect! Normally I wouldn't be as picky when it comes to metal working but because any inaccuracies in the chuck back plate would be affecting all other work done with that chuck I wanted it to be perfect and after about 15 hours of machining I finally had me a proper 4-jaw chuck.
Videos:
Pictures:
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| The disc as I got it at the auction |
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| Facing to size |
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| Facing the second time |
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| Ready for cutting the 8TPI 1.5" diameter inside thread |
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| Another view before starting to cut the inside thread |
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| The finished back plate (0.004" over sized) |
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| Close-up of the internal 8TPI 1.5" thread |
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| Close-up of the finish |
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| Drilling the mounting holes for the chuck |
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| And my 3rd try with the 0.004" over-sized back plate beside it |
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| Turning down the hub 50 thou at a time |
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| Getting ready to cut the grooves |
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| The grooves cut and the tightening collar installed |
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| Another view |
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| Laying out the holes for mounting the chuck |
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| The finished back plate (L) and the over-sized one (R) |
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| The chuck mounted on the lathe |
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| Another view |
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| A close-up of the back plate |
Drill press
Metal lathe
Metal scribe
Digital calipers
Alan keys
Materials:
1" thick by 5" diameter metal disc
Cost:
$0.00
Time:
15hrs
Savings:
$50.00
Conclusion:
I guess the third time IS the charm
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