# Order of Operations



## tonydi (Aug 24, 2021)

I'm going to be machining the part shown in the attached.  It will be made out of one piece of 2.5"OD 6061 using my mini-mill and mini-lathe.  I've been debating on the most efficient and least problematical way to machine this, which order to do each operation.

I've got to make four of these so my current thinking is to machine it from the "bottom up", and do everything up to the hex, flip it over in the chuck and do the rest with the exception of the hex, which I'll do last on the mill. 

Am I just overthinking this or is there an argument for doing it in a different order?


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## pontiac428 (Aug 24, 2021)

It's not overthinking; you need to think things through when starting a part.  I think you are on the right track by machining from the bottom up, flipping the part in the chuck where you have a nice surface to grab, and finishing the part to include threads.  Then you can cut your hex. 

Are you making parts for the Sloan Valve Co.?


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## SLK001 (Aug 24, 2021)

tonydi said:


> View attachment 376152



Your drawing doesn't make sense.  There appears to be a counterbore under the threads that will remove all the threads.  It's the top .50 dimension on your drawing.


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## BladesIIB (Aug 24, 2021)

Couple thoughts. I am not sure I follow the whole drawing with what appears to be a bore after the threads the same diameter?  That aside, how concentric do both ends need to be. Are you using a 4 jaw when flipping or is 3 jaw close enough?  Also if you are using an index head in the mill be sure you have an end mill that can reach. For me my index head Chuck is large diameter and I would need several inches out of the Chuck for spindle clearance to cut the hex. Having what looks like .650” out to the end of the hex would be tough for me. I would machine the top end, thread bore step etc. complete. Then put in the mill and cut the hex. Then cut it off in a band saw or put back in lathe and part. Then turn. Grab to hex and machine the bottom side. If needed I would grab the hex in a 4 jaw and dial in on the small shoulder behind the hex. I may be missing something from the drawing but that would be my initial thought.


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## vtcnc (Aug 24, 2021)

SLK001 said:


> Your drawing doesn't make sense. There appears to be a counterbore under the threads that will remove all the threads. It's the top .50 dimension on your drawing.



Unless it’s a threaded hole and the exposed thread is a threaded adapter… you are right this doesn’t make sense. Plus threading up to a shoulder is very problematic.

Otherwise your bottom up approach seems sound.


Sent from my iPhone using Tapatalk


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## tonydi (Aug 24, 2021)

Heh, yeah, might have been helpful to actually say what the part is!

It's a replacement for the center cap on my wheels, meant to simulate a real center lock hub/nut assembly.  Something like this...




The "threads" are just fake and I cobbled together the drawing with just the threads offset to the outside of that top protrusion.  It's still all just one solid piece of aluminum.

Tolerances?  +/- anything I feel like except for the 2.37 diameter, that one needs to be probably within .010" because it has to fit down in a recess but not be too small.


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## BladesIIB (Aug 24, 2021)

Ok so based on that if the bore goes right through, or even if a partial bore then I would go with top side, hex then back side as I outlined above. That will make sure you have a full shaft to hold in the mill set up for the hex then turn and hold the hex in a 3 jaw and finish the back. As vtcnc mentioned though, that is a tight thread up to the shoulder. For the look you want a relief won’t work?  That will be tricky. Have to turn slow and wind out fast while disengaging the half nuts. At least thread size is not critical so just go until it looks good.


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## Janderso (Aug 24, 2021)

Good thread!
Order of operations for us mortals is very challenging.


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## tonydi (Aug 24, 2021)

BladesIIB said:


> As vtcnc mentioned though, that is a tight thread up to the shoulder. For the look you want a relief won’t work?  That will be tricky. Have to turn slow and wind out fast while disengaging the half nuts. At least thread size is not critical so just go until it looks good.



I wanted the thread to *appear *to continue past the top of the hex because that's how it is on many real center lock hubs.  I was going to chamfer the hex where it meets the thread to make it look like they are separate pieces.  But this is all just rattling around in my head and I wanted to get the basic part done, maybe leaving thread for last.  That's because it's hard to visualize just how the proportions of this whole thing need to be.  It might be too big or comically small, won't know till I make one and slap it in there.

The thread thing may not even be necessary as some real setups have the end of the hub as a pilot and no visible threads.  Obviously that would be a lot easier for me.


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## BladesIIB (Aug 25, 2021)

Makes sense. Saving the thread for last and seeing how it comes together sounds like a good strategy. Can’t wait to see it. Fun project for sure.


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## RandyWilson (Aug 25, 2021)

You might consider making the nut and the threaded section as separate pieces. My wheels have the treaded section mounted into the wheel from behind, then the nut (spinner) threads on the outside. In this case the nut holds a cover over the lug bolts.


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## MrWhoopee (Aug 25, 2021)

How is your threading? Generally, I try to do the most challenging operations early on if possible. Nothing worse than having everything else done and scrapping the part on the last op.


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## Eyerelief (Aug 25, 2021)

I tend to agree with MrWhoopee, make sure the most challenging details are covered first.  I also obsess about rigidity, so I like to do all of my OD profiling first and save the ID profiling for last (if possible and it doesnt compromise the set up) since those steps remove material ultimately weakening the part.  Not a big deal with thick walls, but the less flex in material you have, the more accurate your part will be.


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## tonydi (Aug 25, 2021)

Given that it's for appearances only and most likely you'll only see a few threads, I could probably achieve the desired effect without actually cutting a thread, just some concentric grooves with a threading bit.  I still haven't settled on threads or no threads and the material won't be here until next week so I have lots of time to change my mind on that part twenty times or more.  ;-)

@RandyWilson  Oh, I'm familiar with those knockoffs, having spent 27 yrs in the performance aftermarket biz in a previous life.  We sold a lot of those kits and sold even more of just the 3 wing knockoff part to all of the kids who had them fly off driving down the road!

Not sure I see the advantage of having a threaded adapter for my center lock and then a separate nut.  It seems like a lot of extra work to make something that's fake function as though it was real. It's a lot easier to make it all from one slug of aluminum bar than to make it separate pieces.  Looks exactly the same either way once it's installed.

I'm playing with an idea to 3D print some sort of lug nut cover but will wait until I see what the finished center lock nut looks like.  Your wheel lends itself perfectly to the cover you have, not so much on my wheels.


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## BladesIIB (Aug 25, 2021)

I like the groove idea for easy control and the look you want. Great thinking.


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## RandyWilson (Aug 25, 2021)

Actually, those wheels can be had in either center-lock pin drive or bolt on with the covers. Same nut. They attach a bit better than the plastic spinners the Mustang crowd used to love.  The point I was making was you don't have to cut all the intricate details to make it look two piece in a single block.  Cut the nut. Cut a stub with treads. Attach them post machining. Press fit, even glue.  to me that would be easier than trying to machine it to look like separate parts.


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## tonydi (Aug 26, 2021)

The fake spinners we sold were actually pot metal, chrome plated.  They even offered a brass plated version.  Those things were heavy, though, so heaven help whoever got in the way of one of those bouncing down the freeway!

That was actually my first inclination, to make the hex nut as a separate part.  But finding aluminum hex rod larger than 2" proved to be a tall order. 

Making it from the larger round stock requires the six cuts for the hex no matter if it's a separate piece of part of the one piece.  If it's a separate piece then you have more operations to do to the nut and more material to remove from the "stub".  I think you're trying to make the threading thing easier for me but as I said, it may not be part of the final design and if it is, it's a couple of mins to fake threads.  I was never intending to set up real threads because my mini-lathe can't make a big enough thread pitch to look real.


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## Maplehead (Sep 1, 2021)

I second or third... what Mr. Whoopee said. If the actual order does not matter then I like to do the most challenging function first so as not to waste time. I can't tell you how many of my guitar parts I've made and scrapped after spending hours on them. Foe example, for my bridge I'll spend a good amount of time hogging out the blank and then save the most dangerous part for last, threading the 48 holes. Of course I break the threading bit in one of the holes which instantly makes the wanna-be-bridge useless. Now I'll thread first and then hog out afterwards, and, my new Tapmatic has made threading so quick and easy and tool-breaking-free. So hard stuff first, easy stuff last.


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## tonydi (Sep 1, 2021)

Are there any "challenging" operations here?  IF I do the "thread" part, it's likely just going to be 2 or 3 concentric grooves done with a 60 deg tool to make it look like a thread.

Probably for me the most challenging will be cutting the hex since I don't have anything on my mini-mill except a vise. But today I experimented with a scrap piece of Delrin and a protractor and with virtually no effort got a perfect hex cut in no time.  The other operations are simple turning and drill/bore.

At this point I'm afraid the biggest challenge will be in getting the actual aluminum bar from FedEx.  It was due Monday and yet it's been (supposedly) sitting in SoCal about 600mi away since Sunday.  When this sort of thing has happened in the past, the item never arrived.


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## tonydi (Nov 6, 2021)

Well, better late than never.

By the time the stock got here I had decided to forego the fake threads on the hub.  That's a detail that would have been so small that once on the car it wasn't really going to show up, so, not worth the effort. 

I also decided that the recess in the bottom of the part, originally designed so I could use some set screws to retain the whole nut in the wheel's hub was more trouble than it was worth as well. So I shorted the whole part and just put a 1/4"x20 thread and made some crossbars to register in the wheel hub. (green lines)





After making the first one I felt that it was pretty heavy so I measured it and it was 190 grams!  That begat the six holes in the bottom, which took out almost 80 grams of aluminum!  Plus, I wanted to mess with the circle function on my TouchDRO setup since I'd never used it for something other than a test.

Ok, back to my original question, order of operation.  Yes, it definitely makes a difference, even in a relatively simple part like this.  I considered BladesIIB's idea but since it was the opposite of mine I just chose to ignore the ton of experience and talent he has. ¯\_(ツ)_/¯

So on the first part I machined the bottom stuff first, then flipped the part and did the center bore before removing the part and putting it in the mill for the hex.  As soon as I went to mount the piece in the mill vise I realized exactly why BladesIIB thought I should do the hex first!  The amount of material that the vise contacted was really small, like .245". (red lines on drawing above)  Had I done the hex before the lathe work, I would have had a lot more surface area to grab on to. I knew at this point that I needed to just go slow and take smaller cuts when making the hex.

I finished the first nut and switched to BladesIIB's idea, reversing the order.  I figured once I got the hex done I could then clamp the lathe chuck onto the hex and have a more solid setup.  What I didn't anticipate was that the .250" "hub" above the hex stopped me from being able to get the chuck jaws onto the hex at all!  So I had to grab it with inside jaws, expanding out into the hub ring.  Of course that hub area is pretty thin walled so I couldn't really crank the chuck jaws too tight but it worked out as I again just went to smaller DOC's.

Here are some pictures of the finished project.









What did I learn?  That even when you overthink something, dwelling on it for days and days before starting and getting opinions from people far smarter than myself, there's still going to be something that nobody could have predicted. 

But hey, this was a fun project and it came out as good as I'd hoped and I kept myself busy for countless hours.


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## rwm (Nov 6, 2021)

Those came out great! They look factory. Is that paint or anodizing?


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## BladesIIB (Nov 6, 2021)

All that matters is that the parts look amazing and significant learning occurred.  All the input from others will never be better than that.  Thanks for sharing the final product!


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## MrWhoopee (Nov 6, 2021)

You do some nice work!


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## vtcnc (Nov 6, 2021)

My son likes these, now he is eyeballing my lathe. What kind of car did you put these on? Veloster?


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## tonydi (Nov 6, 2021)

Thanks everyone for the kind words.  @MrWhoopee, but I consider myself a hack compared to the amazing stuff I see made by most forum members here.  

@rwm  It's DupliColor Metalcast paint, made to simulate anodizing.  I looked at real anodizing locally but couldn't get past the $$ for such a small job.  I'm sure somewhere down the road they'll need to be painted again but I've got another can ready to go.

@vtcnc   No, it's a Genesis Coupe Track 3.8.


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## tonydi (Nov 12, 2021)

Oh man, I could have used this setup last week!


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