2020 POTD Thread Archive

Today i had some time to spare so i decided to spend it cleaning the machine shop, it was a real mess the first picture is after one trash bag full and an hour of cleaning and to finish it took me 3 hours in tatal and 2 trash bags.
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I hope that's not the garbage pile in picture 1!
 
I hope that's not the garbage pile in picture 1!

Yeah that one, i keep some of the drill bits and handles, there was a lot more on the left. In fact there was no space to walk around and work.
 
You need a larger warehouse.
 
That's one honkin' huge drill bit in your first picture!
 
wow, that is simply beautiful. I had dreams of building my own bass guitar when I was a teenager and played it, but never got further than that. How's it play?
 
I started making the backplate for the 3" independent 4-jaw chuck for the dividing head (1 3/4-8 TPI). I bored it first :

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I used a small threading tool (too small for the 1 3/4-8 thread) to try and get the thread close. I switched over to a larger boring bar to hog out as much as I could without deforming the thread. Then (because I wanted the thread perfect) I used a 1 3/4-8 tap to finish the threads :

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One has to check the thread to make sure it fits the intended target, so, yeah, I picked up the entire dividing head and threaded it in to make sure :

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Next was getting the thread sizes. It's a three-bolt-pattern. I measured using actual pins here, but took the picture without the pins as the reminder of what I did when doing the calculations :

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With a segment spacing, of 2.25", I could start calculating the diameter of the pattern. I spent about a half hour on it before my brain kicked in, and I grabbed my Machinists Handbook.

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There is a table of segment sizes based on a 1" diameter. For the three segment pattern, the segment size is 0.866025" . I divided the segment size (2.25") by the table size (0.866025") and got 2.598". Divided by 2, and it's a 1.299" radius. Now, I can put the back plate backwards on the dividing head, install it to my mill centered on the spindle, and then move the table 1.299" in any direction, and then I can mill the pockets and drill the holes for the bolts, yank the plate and install the chuck.
 
While out running errands today I picked up a dozen 4" x 5/16" bolts, nuts, washers to fasten the lathe to the bench.
Tonight I marked the holes, shift the beast over, drilled and bolted it down. Feels permanent now :)
I think I'm going to turn a test bar to check alignment.
 
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