I added the images you sent to the post above. Thank you for taking the time to duplicate your original setup and take pictures.

Like I mentioned before, you came up with a great solution by using your lathe to cut the slot. I was always worried that lathe owners looking for a first project would be put-off by the fact that you needed a mill to complete this project. But not now!

Thanks again for your contribution!

A regular 1/4″ set screw (Which I think is what is in the plans?) would have been fine in the slot, except the inner shaft size I used was just under 3/8″ so there wouldn’t have been a lot of meat left to hold the 1/4″ set screw.

I also don’t care for the idea of using a threaded set screw shaft as a stop… a nice turned section seems a better fit.

Besides… I had a #6-32 handy and didn’t have a 1/4″ set screw. ;-P

I also used the mill to make a flat on the shaft before drilling/threading for the cap screw.

I’ll go shoot some pics and re-create the wanna-be milling set up.

(My lathe is an HF 8×14, BTW… I could have accomplished the same with the stock turret and shimmed it just like a cutting bit.)

I’m glad to hear you enjoyed the project. I use my original spring center almost daily (well, at least every day I work in the shop). It has been the most useful shop-made tool I’ve ever made.

I’m also glad to learn of the technique you used. I’ve been trying to figure out how to make this a lathe-only project. I had considered chucking an endmill and holding the part in a milling attachment, but I hadn’t even considered holding it in a QCTP. I need to check, but the part might actually be small enough to fit in the 4-way turret style tool post that some lathes (including mine) come with. If so, that would make it easy for anyone to take your approach to cut the slot.

The only thing I didn’t quite follow was your last sentence. Why did you need to remove material from the head of the cap screw?

Also, could you send a picture of your completed spring center? I’d like to post it here. If you have any pictures of the setup please send those my way as well.

Again, I’m glad you had fun with the project!

Tyler

I made mine a bit smaller, to suit the stock I had on hand (5/8 Drill rod) but I think it’s still plenty beefy for the job.

I don’t have a mill so I clamped the outer part in to a QCTP toolholder and milled it that way. By first lining up the toolpost against the face of the chuck, then adjusting the height using a centering guage (you could also use a dial indicator) I got everything squared up and in line.

Then I just chucked up a 5/16″ end mill(Remember mine is slightly smaller scale) and took several light passes until I had a nice slot ready to go. It worked like a charm and made it a Lathe Only project!

I used a 6/32 socket cap screw and just took a light pass off the head until it ran through the slot without binding.

You’re right, this project can seem daunting at first. In fact, it was the first project I ever completed on a lathe and I got stuck in a few spots. The other limitation this project has as a first-time lathe project is the slot for the set screw, which really needs to be cut on the mill. So in all reality, it’s kind of a lathe/mill first projet. You can cut the slot on the lathe, but you’d have to secure the part to the cross slide (preferrably via a milling attachment) and cut the slot with an end mill that is held in the chuck (or better yet, in a collet if you have a collet closer for your lathe). Those limitations aside, here are a few pointers.

First, the 30 degree angle (a 60 degree total, or “included” angle) is indeed cut with the compound. To do so, set the compount at 30 degrees from the axis of the part. If your compound is set to zero degrees (so the tool is cutting along the axis of the part, and the handle of the compound is pointing toward the tailstock, or toward 3 o-clock), turn the compound 30 degrees in the counter clockwise direction. The handle for the compound should swing toward upper right (or about the 2 o-clock position) and turning the handle should move the cross slide toward the lower left (or toward the 8 o-clock position).

Once you’ve set the cross slide at 30 degrees, you’re ready to start cutting. Take little cuts in the same way that a pencil sharpener cuts a new pencil. What I mean by that is, if you stuck a pencil in a pencil sharpener and turned the pencil one rotation, the 90 degree edge of the pencil would be slightly chamferred. Another rotation of that pencil would make that chamfer larger, until eventually you’ve got a point on the pencil. Do the same with your cuts. Take a little cut to just barely chamfer the 90 degree edge, then take another cut a few thousandths deeper until eventually you’ve got a point on the end of the part. Make sense?

The other problem you might run into is drilling out the hole in the other part. Use a center drill first (always), then a small bit, maybe a 1/4″. Don’t bury the bit all the way into the part, doing so might cause the bit to break. Drill that 1/4″ hole a half or maybe 3/4″ deep (dependign on the lenght of the drill bit and the quality of the drill bit you may be able to go deeper). Once you’ve got the hole 1/2″ or so deep, chose another bit between 1/4″ and the final size – like a 3/8″ bit. Drill that hole to the same depth as the first. Then pick a drill bit that is at the final size (I don’t have the plans open, but I think the final diameter is .500 or 1/2 inch). So pick a 1/2 inch drill bit and drill that to the same depth. Then do the entire process over again (1/4, 3/8, 1/2) until you’ve got the hole to the proper depth. If you were to just center drill and chuck up a 1/2″ bit you’d run into problems. Your lathe might not have the HP to drill such a large hole all at once, your bit might wander or cut a non-round hole, or your bit might start to slip in the chuck. You want to try to avoid all these things. Also, use cutting or tapping fluid while drilling the hole, and retract the bit ever 1/8″ or so to remove the chips that build up.

Now, if you really want that hole to be perfect, you need to drill it slightly undersized (like .480), then bore it a little larger (like .498 or .499), and then ream it to size (.500). That’s the best way to get the hole perfect. I didn’t do that with my project because I wasn’t trying to get a perfect hole. I just needed it close. It’s up to you. If you have a .500 reamer and a boring bar, go for it. If not, don’t worry about it.

The hole for the set screw can be drilled and tapped on a drill press using a v-block or even just a vise, but a v-block will help you drill the hole perfectly perpendicular to the axis of the part. Tap the hole at the same time (avoid removing the part between drilling and tapping to help ensure that your tap starts straight).

Again, the slot is best cut on a mill. But you could use a drill press with an end mill and an x/y attachment, or you can cut the slot on the lathe if you have a miling attachment for your lathe.

Other than that, everything else should be pretty self-explanitory.

Oh, and to answer your question about an easier “first time” lathe project. I don’t have a set of plans right now that would be easier, but you might try to find the set of plans by South Bend Lathe Works for the plumb bob (it’s Project Number 3). It’s very easy. It’s basically a plumb bob cut from a piece of hex stock. It’s one piece and simple. Another idea (also in the same book of plans) is for a set of punches (center punch, drift punch, nail set, ect). They are also turned from hex stock and can be cut to whatever size you might need.

Here’s a link to the book on e-bay:
Machine Shop Projects by South Bend Lathe Works

Last I looked the book was listed for $12 – worth every penny. You can also try to google the book if the link above is dead. Lindsay Publications also sells the book so include “Lindsay Publications” in your search if you have trouble finding the right book.

If you have any other questions or get stuck leave another comment and I’ll try to help you out ASAP.

Good luck and thanks for visiting!

Tyler

For example, i have no idea how to achieve the 30 degree conical turning. I mean, i have the idea of where to put the tool, but how do i advance into it to get 30 degrees? Perhaps something to do with the compound angle that I’m missing?

Is there another project (with pedantic instructions) that i should maybe try first?

Thanks for any help!