Order of things

M

Maplehead

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Pictured is a "screw" I am making from 3/8" rod. The ones that get completed seem to be out of sheer luck as many fail because my order in turning the different parts always ends up with some issue. I have tried mixing the order up. I get the best results doing this order:
1. Cut rod to 2.5" long.
(Final length is about 2".)
2. Create knurl (lol)
3. Turn first 1.125" of long end aside knurl to .109".
4. Thread turned end to 4-40
5. Connect live center to threaded end and continue turning after threads, up to the knurl. Again turn to .109".
6. Camfer knurl on turned side.
7. Take out piece and screw into steel tube.
I made a 1.5" long, 1/4" OD steel tube with an ID just over .109" and threaded to 4-40 at one end.
8. Insert steel tube with brass piece into 3-jaw chuck.
9. Turn short end of brass piece up to the knurl to an OD of .109".
10. Camfer this side of knurl, making a 1/8" wide knurl for turning "screw" with finger tip.
10. Grind threaded end so that threads are 1" long. Grind short end so that total length of "screw" is 2" long.
DONE

Without going into the issues I am having, would you all take this approach or do it differently?
Would you change the order of things?

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Maplehead, unless this is for an application that I don't understand, I believe I would make it from two pieces. Too much wasted brass for my liking, and I make parts out of brass all the time for old clocks.

For the threaded section I would start with 1/8" brass stock, and use the 3/8" for the knobs. Easy to knurl and part off the knobs, having drilled the hole for an interference fit. Or the shaft could have a slight knurl where it will have the knob located. If there isn't much torque involved then loctite could work with just a snug fit.

David
 
I agree with David's take on things. Making the parts as two different pieces would definitely be my approach.
 
I think David has the right idea. your part will probably be more accurate end to end that way, as turning it around plus adding a holder and a 3 jaw chuck must make the ends not concentric.
Maybe that doesn't matter for your application.
I would try it Davids way with a knurl on the small shaft that the wheel is press fit onto.
 
Hi David

Yeah, I hate having to turn off all that brass.
The ends of this "screw" are seated.
There will be a 1/4" thick by 1/2" wide and deep brass piece that rides along the threads. So that's what the application is.
Parting is not that easy on my little lathe. I would have to part the knurled wheel and then camfer and then finish parting, correct?
 
I would drill the center hole. Chamfer the end. Start the parting cut. Chamfer that side (done with a 60 degree tool you could chamfer that and the new side of the next wheel at the same time)
Now knurl the wheel.
Finish parting. chamfer (deburr) center hole (by hand).

There are more things to consider. like..drill size and if reaming is needed (likely).
And if the outside of the stock is to be machined concentric first or not.
I would chamfer/deburr the hole in the first side while it is still in the lathe.(can be done by hand)
 
rgray said:
I would drill the center hole. Chamfer the end. Start the parting cut. Chamfer that side (done with a 60 degree tool you could chamfer that and the new side of the next wheel at the same time)
Now knurl the wheel.
Finish parting. chamfer (deburr) center hole (by hand).

There are more things to consider. like..drill size and if reaming is needed (likely).
And if the outside of the stock is to be machined concentric first or not.
I would chamfer/deburr the hole in the first side while it is still in the lathe.(can be done by hand)
Click to expand...

Russ, a few questions.
Knurl the wheel and not while it's still rod stock?
Why chamfer the center hole? Is that to allow it to slide onto .109" piece?
What exactly is reaming?
 
Maplehead. It does help us give better advice if we know what type of tooling you have. Thank you for mentioning you have the Grizzly micro lathe.

What are you using for a parting tool? I would think for that lathe that a narrow parting blade would give best performance, or a lathe tool ground quite thin.

David
 
Hi David
I ordered this bit set from Grizzly when I ordered the lathe. The parting tool is 1/8" wide. I ordered an HSS 1/16" one from eBay but I am still awaiting it.
I looked up reaming. I'm guessing for my needs a drill bit will suffice?

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First for your lathe the thinner the parting tool the better. Like I mentioned, mine is 0.040" wide and I have one that is thinner that I ground from a HSS blank lathe tool.

In the absence of a set of reamers I would drill the hole in the knob first and then do the final turning of the threaded piece so that you can get a slight interference fit to the knob or alternately use loctite.

David
 
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