Need help machining a Smallish Steel Part

Hey machine shop folk, I’m trying to force a thing to start existing because it’s far less useful bouncing around inside of my head than it is in the real world. But I have approximately no experience making metal things, and exactly no sanctioned training on the machine tools.

The part in question is a hall-effect trigger wheel roughly 2.3" in diameter that will eventually help a pair of sensors tell my engine management what its spinny bits are doing.

Plastic prototypes have been promising in terms of fit, so I’m just about ready to go for the real thing in steel, but the quotes I’ve gotten to machine it one-off have been steeper than my pockets are deep, with backlogs long enough that human-driven cars will be illegal by the time they get around to it.

So I’m looking for advice or help in turning this into a thing rather than an idea. I’d love to take the Haas training and try to figure it out myself, but my schedule doesn’t line up with what I’ve historically seen on the calendar, so until I get that worked out, and training starts again next year, that doesn’t seem likely to be a thing. Any thoughts?

(Side note: there is a version without the spokes that I imagine would be easier to machine, but it doesn’t look as cool)
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Devil’s advocate:
what’s with the shape?
Most hall effect sensor tone rings are simply “gear shaped”, e.g. these on an ABS wheel
image
or sheet metal like this one


Here is one from a Ducatti, where the flywheel starter gear is employed in double-duty
image
and another where it’s basically sheet metal, keyed to the crankshaft snout
image

Part II of Devil’s advocate: what kind of engine? Many of them already have something which can serve as hall effect tone generators; e.g. the starter ring gear, camshaft gear(s).

At any rate, if you can use something simpler like those, you could probably cut it on the PlasmaCAM easily enough, though getting it “just right” might take a trial or 2 and some cleanup. It looks like you’ve already got the CAD file, though. Just need to optimize for that.
:+1: Curious to see the finished product…

You could likely to that on the dividing head. It would take likely multiple setups to do. Shapeoko might but I’m not sure if we can do steel on it.

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The Shapoko isn’t going to do it - the rule is no cutting fluids.

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Constraint of the engine it’s going on:

There’s no practical way to read from the side on this engine, which makes those styles of trigger unusable for the application.The only place to stick a trigger is in the stock exhaust cam location, so it has to fit inside of the cam gear.

Moreover, there are no off-the-shelf parts that suit this engine and my engine management solution. I can have one or the other, and even if I have to farm this out to a job shop, the custom piece would still be cheaper than an engine management solution that is compatible with any off the shelf options. (Which are also small-production-run parts, but they’re from New Zealand, cost even more than I was quoted, and the vendor isn’t willing to ship farther than Australia) Even the OEM part, which isn’t compatible with my EMS, will set me back more than the quotes I’ve gotten.

This is what I get for building an engine that isn’t available in the US, but damn.

Give Nick Silva a little while to check in. He’s our resident Haas expert, and can probably give you a good candid evaluation of the how of it. Given that you already have a 3d drawing, the haas might be the best way, but going to take a Haas guy to tell you.

definately a cnc type job. fixturing it could be the real issue since we don’s see a backview. The way the ‘teeth’ stick out from the surface is ok if the back is flat. however, if they also protrude from the back you’d probably need to cut a fixture to secure it as well as to correctly align it for a flap. That one lone tooth that sticks out is just annoying (but doable). I can see why the quotes are high, this will take a long time to cut. Being steel, it will require better tooling than we have on hand. I won’t be around much for the next 90 days. an alternative might be to check with
Shapeways for a quote. I think they are now doing a metal 3d print. good luck.

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If you are reading this face on only, you don’t even the outside features either. I would lathe turn the blank, possibly including trepanning out the volume not in the main teeth, or your indexing pin, then use the dividing head to cut the teeth. They would wind up pie shaped, unless you went to some extra work, but I doubt the sensors would care as long as enough metal is there.

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Here’s a view of the back of the part, taken from Shapeways’ viewer: (I don’t have access to the home desktop for anything better right now)

None of the features on the back face are critical. Only the 4 bolt holes and the teeth, including the lone tooth (cam sync) are really critical features.

On the topic of Shapeways, 2 problems:

  1. Shapeways’ steel product is a 60% 420 Stainless, 40% bronze composition with very weak ferromagnetic properties. As the part is a hall-effect trigger, that material is poorly suited to it.

  2. The part fails their automatic checks. I haven’t looked into what the issue is yet, and I probably won’t, considering part 1.

@kbraby might be onto something, but I also don’t have any lathe experience or training.

Okay, here is how I’d do it for a simple accurate functional piece:

If you want the cool slots in the first picture, can easily be done on rotary table.

Turning on the lathe will give high roundness.
Rotary Table allows machining round/circular items concentric with center.
I it does hurt, when On lather It put a center mounting through so when put on rotary table, no guess about center. If you can do out of Aluminum - very easy.

Alternative: Take Haas class and machine out of what you want, engrave name, log, whatever.

While the teeth can tolerate being tapered toward the part center (pie shaped) they do need to be basically the configuration shown.

For some background, the part is intended to be a crankshaft position trigger with camshaft sync, located on the exhaust camshaft. The outer ring is made up of 36 teeth with 2 removed at opposite positions, to allow the camshaft to emulate 2 identical 18-1 trigger wheels, since the ECU being used is unable to interpolate crankshaft position from camshaft position in software. (Camshaft rotates at exactly 1/2 crankshaft speed) The additional tooth triggers a second hall effect sensor offset from the main ring, to provide camshaft position to the ECU. (Known as Cam Sync Trigger) All teeth need to be 2mm wide at minimum, with at least 2mm spacing between them, due to limitations on sensor resolution. Cam sync tooth must also be at least 2x2mm square. (2x3 was chosen to improve resolution at lower sensor sensitivity needed to remove any noise from nearby cam gear mounting bolts and main trigger ring)

Regarding the Haas classes, are there any trainers aside from Nick? Being as he’s not available for the next few months.

I understand about the gap and hale effect transducer, it’s the up and down, on the outer diameter between the uprights I was referring to, that can be done, using an indexer, but lots of work if not functional.

Part can be made, but a fair amount of time.

Do you have the old one? have you considered making a silicone mold an casting a new one?

There is no “old one”. This is an all-new design to replace an OEM sensor which is based around a 360-slit optodiode trigger wheel that is in no way compatible with my EMS solution, due to hardware and software limitations. Additionally, not only did my old sensor fall to pieces, but replacements aren’t readily available.

Also, metals that can be cast in silicone aren’t suitable for hall effect triggering, and I don’t have the facilities to try making a quality steel casting of a 3D print of the part. (As an aside, 3D printed prototypes have come out decently, so I’ve got that going for me, which is nice)

Could you do this? Use the Shapeoko to machine it out of pink foamboard. Once you have it right, use the “lost foam” method to cast it out of aluminum.

Just curious - if the Hall sensors are pointed at the face of the wheel, what do the radial protrusions ( past the edge of the disk ) do for you ?

As noted above, those are going to be a real pain to machine, whereas if you extend the disk out to the ends of the teeth radially, it gets a LOT easier.

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Needs to be steel if it’s for Hall sensors. Aluminium is non-magnetic.

Ah… that makes sense. Still, melting aluminum would be fun, but I digress.

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Best way to fixture this on the HAAS is to super glue to it another piece of steel that could be held in the vice.

The piece in the vice must be machined flat and square on all sides, it also should be made out of the same material as your part or else the difference in thermal expansion could cause the super glue to break.

The part of your stock that is super glued to the metal in the vice must also be machined flat.

It’s very important that your part remains cool or the heat will cause the super glue to let go.

This way of machining will create less chatter than fixturing it with bolts.

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Agree Haas would be best - but he can’t just Haas for probably two months.

@suchsojasco what is diameter and and thickness?

For fixturing:

Cylindrical billet, 4 oversized holes to main face depth, and then continue the holes through at proper sizing.
Then you could bolt the entire face to a backing plate.

You’d have to be careful that your toolpathing didn’t cross over where a bolt was holding the thing down, or you’d crash a mill but that’s not impossible.