Introduction: Machining a Tailstock Die Holder for the Sherline Lathe
The Sherline Lathe would have to be one of the best value tools I have in my shop. It is incredibly versatile, very accurate, and well priced. Sherline also have an excellent 'open source' approach to the way customers can access their products. Every single part, no matter how small, is available for individual purchase. This means you can selectively buy what you want and then hack, tinker, and experiment as much as you want, to meet the needs of your project. It makes their products extremely versatile.
They also have a dizzying array of useful accessories for their base lathe and mill. I'm not exaggerating when I say I developed a serious tool addiction when I started collecting extra bits and pieces for my Sherline lathe!
However, one tool that I haven't seen from them is a sliding tailstock die holder, of the type that is so commonly available for larger lathes. So this week, I set about designing and building one.
I hope you enjoy this instructible, and be sure to subscribe to my YouTube channel for more tool making video's!
- 1 x 5/8" mild steel rod x 4.5"
- 1 x 5/16" mild steel rod x 2"
- 1 x 1.5" Aluminum Rod stock x 3"
- 8 x M5 (or SAE equivalent) Grub screws
- Super glue
- Dial Test Indicator
- Milling machine, or drill press
- Drills and taps
- Butane Torch
- Calipers or Micrometer
Step 1: Draw Out Your Design
You don't need a fancy set of drawings, or a CAD program to make this tool. I do it this way because I sell the plans on my website.
But you will need something to keep you on track. You can easily work from a basic "chicken scratch" plan, written down on a shop notebook. Watch the video for a clear idea of the features you need to consider, and then start laying it out in a way that makes sense to you. That's the key by the way - It doesn't need to be an engineering masterpiece; just make it readable for you.
The critical dimensions are:
- The 2 die recess bore diameters, and recess depths
- The shaft and inner bore of the tool must be a nice sliding fit
- The grub screw angular spacing (refer diagram above.)
Step 2: Start on the Main Body of the Die Holder
Chuck up a suitable* section of rod stock, then face both ends.
Spot drill, drill, and then ream the central bore to the desired dimension. I selected this bore dimension based on the reamers I have available in my shop. I suggest you do the same. it's not critical, so just run with the closest one you've got to about half inch.
Then start hogging out the recesses, but leave them undersized. You're going to get tricky in a moment, and take them to final dimension using a very accurate method.
* Regarding material for the body, I used aluminum. Its easy for me to source, easy to machine, and durable enough for light duty use on something like this. Steel would have been more durable, but the weight hanging off the tailstock would have been considerable - too much for the little Sherline tailstock I think.
Step 3: Turn the Recesses to Final Dimension on a Stub Arbor
Load a piece of drill rod into a collet chuck, that matches the reamed internal bore of the tool body. If you don't have a collet chuck or drill rod, no problem. Just turn a piece of stock in a 3 jaw chuck, to the required dimension. What you're aiming for here is a dead true stub arbor to mount your embryo part on.
Mount the part onto the stub arbor using a few drops of superglue. You don't need much; capillary action will draw it in. It holds incredibly well, and sets very quickly. The reason you are doing this is to ensure that the die recesses are concentric with the central bore.
Measure all of your dies, you may be surprised to find that they are not all exactly the same. Note the largest thickness, and the largest outside diameter. This is the dimension you are aiming for, with your recess. Some of your dies will therefore be a slightly looser fit than others; that's just the way it has to be.
Carefully bring the first recess to final dimension. Sneak up on that last dimension slowly. You'll kick yourself if you go over, and the die has a loose fit. You now need to flip the part to do the other end.
Gentle heat will break the superglue bond however NOTE: Be sure to use breathing protection when heating superglue.
Remove the part from the lathe (stub arbor still attached) and then gently heat the part with a propane torch to break the superglue bond, and then remount the part and repeat for the other end.
Step 4: Profile the Tool Body
What you do here is entirely subjective. I like the feel of straight knurl tools, and I put in a recess in the center to make it more pleasant to hold. I milled the knurl with a fly cutter using a vertical slide on the lathe, but you could just as effectively give it a simple diamond knurl and be done with it.
Step 5: Drill and Tap All Holes
I used a dividing head on the mill to drill and tap the grub screw holes, and the handle hole. If you don't have dividing facilities, don't worry; you can simply mark this out manually. A protractor and scribe will give you an accurate enough result, if you are careful. Remember this is not super critical; the dimple pattern in your split dies is able to tolerate a reasonable amount of error in the layout of these holes.
Step 6: Turn the Long End of the Shaft
Chuck up a piece of appropriately sized mild steel to make the shaft. Prepare it for turning between centers, by facing and center drilling.
Set up between centers, mark out and then turn the long cylindrical shaft to final dimension.
Remove from the lathe when close to the final OD, to confirm the fit with the main body of the tool. You are aiming for an easy sliding fit. Not too sloppy though; you still want the tool to operate on the axis of the lathe.
Step 7: Turn the #0 Morse Taper
There are a few ways to turn a taper on a lathe. I chose to copy the taper on an existing #0 MT, by setting the compound to track it. Refer to the video for more detail.
If you follow this method, be careful to ensure that your indicator is travelling along the exact middle of the taper you are copying. Otherwise you aren't really tracing the taper correctly. Once you have this angle set, you can lock down the compound, and take the cut by feeding in with the compound.
Alternatively, you can indicate in the compound using an DTI on the chuck body, using trigonometry to confirm your compound angle, or you may even be lucky enough to have a taper turning attachment. A last resort is to move your tailstock to the appropriate offset to achieve the taper. I mention this last, because I really don't like having to mess around with the tailstock again when I am finished!
Step 8: Turn the Handle
Now for the fun part!
Form a thread on one end of a suitable piece of stock, to match the hole in the main body, and then get creative with the handle grip. I like a groove pattern, but maybe you would like a diamond knurl? A straight knurl? Perhaps a heat shrink coating? Your call, have fun with it; you're on the home stretch!
Step 9: Cone the Grub Screws
The last bit of turning is to put a 90 degree cone on the ends of the grub screws, so that they seat into the dimples in the die correctly.
Step 10: And You're Done!
Assemble and enjoy!
I hope you've enjoyed this, my very first Instructable. It was a lot of fun to put this tool together, and I can tell you it has been getting a solid workout since I made it. I am certain that you will be very glad you made one too.
If you liked this Instructable, or if you can suggest some ways to make it better, let me know in the comments below.
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