Can I get some advice for my first Sherline Lathe project


#1

I took the Sherline Lathe class a few weeks ago and have been wondering what to do with the aluminum rod I was given to practice on. I decided the first thing I would try is to make a little aluminum vial. Can anyone check out my plans and let me know if I need to change anything?


For the vial
simple%20vial
-cut off 2.10" section of 3/8" rod on the bandsaw
-face .05 from both ends bringing the workpiece to 2"
-take a light turning cut to clean up the finish
-use the center drill to mark the center of the top
-drill a pilot hole to the full 1.9"
-work the bore up to the .3" diameter
-angle the headstock so I can make the 82 degree chamfer
-thread .3 diameter hole .30" down from bottom of the chamfer (it says .25 on the drawing but I goofed and didn’t want to re-do the drawing)
For the cap

-cut a 1.15" section on the bandsaw
-face .5 off each end to bring it 1.05"
-take a light turning cut to clean up the finish
-turn .3 from end down to .3 diameter
-turn the last .05" of the previous step down to .25 diameter
-flip and knurl down to the chamfer
-flip back and thread the last .25"
-canter punch and drill hole in the side of the cap and drill on the drill press.

Am I to much the noob to know if I’m missing something or have something out of order. Any Elmering would be appreciated.


#2

BTW this was also my first poke at fusion 360 aside from the HAAS training on the domino. It took a little bit to get used to the interface compared to solidworks but I like it.


#3

Great first project that tries a lot of things.

The two critical dimensions you’ll need to worry about are the threaded parts. The rest can be off and not seriously impact usability. You’ll need to establish the tolerance limits for the hole to be tapped/threaded … then the major diameter of the cap portion to be threaded.

I’ll give you my piece of rod so you can practice this several times - this is going to be your critical features. Boring the right diameter hole shouldn’t be a challenge. What I would suggest is you make sure you have the right drill size, the right tap to do it, and then the matching die for threading the cap. You may have to tweak your design to match the tools you have available.

You’ll need to research what the limits of the major and minor diameter of threads are so you’ll know how much you can be off in one direction and compensate in the other (It’s not much). Practice doing this successfully a couple times before doing any of the other work. When you’ve done that, the rest is easy peasy with lots of slop tolerance that will still make it functional.

I have a Orange Bin in the Galley, middle height, in the middle section along back wall. Labeled David Kessinger. The rod is in there. Feel free to go get and practice doing the threads before anything else - and have at it. Threading isn’t that difficult - but things have to be cut straight, threaded straight and within limits.

RE: Dimensions. You need to dimension what the hole size is for the threaded hole. You are referencing off the outer walls - the hole size for the tap is critical unless the .26" bore diameter is the minor pitch diameter (i.e. the size hole that will be tapped. That needs to be dimension to .XXX" -.000" + .010" would be my recommendation. If undersized too much will be hard to tap and may break the tap. You’ll need to dimension the .3" dimension to .XXX" +.000" ~ -.010" (or .015") not perfect for threading but workable - assuming they aren’t at the limits going the wrong way. E.g. small hole large cap, large cap, small hole.

I know people get annoyed with me because I always ask “What’s the tolerance?”

Using this chart your .3" dimension could be .1"~.5" (.4" range) - not acceptable. If .30" then it can .29" ~ .31" a range of .02’ that would be the absolute limits, IMO (but it also means if the hole were at the small end it would be .1", if the cap at max diameter it would .27", this equals .17" or a little over 5/32" which is more than the threads and half the size of the hole), notice the ranges I gave above are TOTAL ranges that would equal ±.005" if the nominal size is centered on the dimension.

Hope I haven’t confused. But the make or break features are the threading. Master that first.

Good Luck


#4

Do you know what size threads you are going for? Additionally you may need to either do a starting tap, followed by a bottom tap or you may have to go deeper on your internal shoulder.


#5

I’m going to throw out an idea and let the others comment.

I think that with your vial being (nominal) 2" long and 3/8" diameter it may be long and wobbly. The hole through the spindle is 0.405", so in theory your part should fit entirely inside the headstock/spindle. I think I would cut it to length(ish) on the bandsaw, face the bottom end, turn it over and face the threaded end, and with the vial almost completely inside the chuck I would do the various chamfer/drilling/tapping operations. This way it would be held steady and on center while you are doing the dimensionally critical bits.

At this point the outside of your vial may be somewhat scarred so then I would do the light finish cuts to clean it up. It doesn’t matter if those aren’t perfectly concentric.


#6

Here are what I currently have modeled.


in another group I was recommended making the bore .257 for a 5/16ths tread to mate with a .3 .
I didn’t really know what sizes of dills and taps are available at the space. I’m fine with changing my dimensions this was basically just arbitrarily sizing things based on what fusion popped up when I hit the thread button.

So then if you asked me my tolerance I’d say ±.005 for this. Too ambitious?

@John_Marlow I think that’s a better plan. One thing most people recommended was just using the bandsaw the once and turning the cap off.