What tooling is used for making internal splines?
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  1. #1
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    Default What tooling is used for making internal splines?

    I want to make internal splined shafts. How do people do it? I have seen some info, but no suppliers, just a few random videos or links without sources. I have seen a few rotary broaching tools, but not a supplier of the tool or tooling. I have seen people using a mill or lathe like a shaper with a single tooth cutter that plunges into the piece. I also recall seeing air powered shapers that could be mounted on a lathe at some trade show, but I don't know if it can only cut a keyway or if it can cut splines.

    I am using a large mill, a Deckel FP50CC/T and a Hardinge Superslant with a rebuilt controller that we can add any IO as desired. The Deckel is an old PLC (Dialog 11) but the Hardinge is running LinuxCNC and I can write any code there. I can lock the spindle at any angle.

    I am looking at broaching holes for 22mm and 50mm shafts.

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    "I have seen a few rotary broaching tools, but not a supplier of the tool or tooling."

    Have you by chance googled "rotary broaching tools splines"?
    Or the video by Slater Tools showing how to use their rotary broach tooling on lathes and mills to make internal splines?

    Asking for a friend.

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    22mm is getting close to the max size for rotary broaching with commercial tools. If you can index your lathe spindle and lock it as you say, you can just slot the splines with a properly shaped tool. PH Horn may have the tool or be able to make it for you.

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    Higher quantities (e.g. automotive etc.) were commonly done with an in-line multi-multi-tooth broach -- very pricey tool and requiring equipment to drive it you don't have. That would be a job you send out.

    As others have suggested, you might be able to get something from Slater or others, but that tool will require a fair amount of force and won't be cheap. Likely limited in depth of engagement as well. Never seen a rotary broach for 50mm and suspect the tooth load would be too high in all but the softest material. The rotary spline types typically available are also pretty shallow. Not the deep form you'd typically expect from, say, a PTO spline.

    Mud's approach is likely what makes sense for low quantities.

    Never done it, but I suspect you could make a broach guide and grind an ordinary key broach to tooth form and, slightly faster than stroking one at a time, cut internal splines (one at a time in your guide) and have it last long enough to do several between sharpenings? Would only be as accurate as your guide and ground-to-profile broach.

    It's possible to buy off-the-shelf internally broached profiles, which you might find some way to incorporate in your design ??

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    Rudd,

    I was searching for a few days in my free time. I found a few seeing sites talking about broaching, but not specifically making splines. I found a few companies, but it didn't always line up. I kept on finding semi-incomplete leads. Like, I would find a website that claimed their tool may work but when I try to find a part number or a document describing it, they didn't line up. The one I did find was a supplier in Australia that looked like a website from the early 2000s.

    I also don't know how much of what I was finding on searches was a product I could use. I found a few videos of rotary broach tools that looked like it was doing what I want, but without a company lead, I didn't know where to look.

    It felt like trying to find information on spherical sheet metal forming processes. The odd video here and there, but when I tied to find the exact suppliers or manufacturers I was given PR responses and not the actual tool.


    As for going forward, I will look at those companies. A lot of times it is finding the name of the company is half the battle. Thank! I think I may have to use a single tooth cutter.

    The machine is for a grinder, so about 10klbf-in torque on the shaft. We found some tsubaki shaft clamps that work, but not ideal and we would like to go into splines.

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    Why reinvent the wheel? There are large numbers of pieces with internal splines such as you describe. They are listed as U-joint yokes and driveshaft slip splines. Figure out how to use existing parts and concentrate original thinking on the portions of your project that don't have off the shelf solutions.

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    Can you explain what you mean here:
    "10klbf-in"
    because I read it 10,000 foot pounds inch. Which doesn't make sense.
    Grob makes splined shafting and splined bushings for example.
    Cold Rolled Broached Sleeves & Flanged Bushings • US Made | Grob Inc.

    Hoping I won't get banned here, but Thermite once said something to the effect of "Only make what you can't buy, pilgrim."

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    We broach ours

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    In a grinder for grinding up material the torques get big, so yes, 10,000 inch pound-force of torque.

    As for reinventing the wheel, we have the main motor to a garbox and output shaft to a grid coupler to the main shaft. That goes to a secondary gear for the opposing grinder shaft. Shafts are machined hex.

    The piece of equipment goes into a machine about the size of a wahsing machine. As a result having large grid coupler and compression hubs adds almost a foot to the size of the machine. As well, most competitors use splined shafts and gears. Our gears are off the shelf catalog gears with a machinable bore.

    I do not want to do something new. Many companies that make grinders have splined gears. I do not have any realistic price for how bad an idea it is to machine our own splines. I do not have a solid idea of what spline tools are on the market are common or not. I cannot make a educated answer to if we should use splines until I know that cost. I can find videos of some unique setups making splines but I can't find the price or cost for us to use those tools.

    In terms of a solution, I think that idea of getting a custom single tooth broach may be a good way to go. Make a rigid jig to rotate the broach to each of the different splines. There is also using a single tooth cutter and driving the spindle or turret like a shaper. Those are the two leading paths I think could work for me.

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    PH Horn could make something like that. I just quoted a very similar tool to what you want through them for a customer.

    How deep does the spline need to go?

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    Quote Originally Posted by Rudd View Post
    Can you explain what you mean here:
    "10klbf-in"
    because I read it 10,000 foot pounds inch. Which doesn't make sense.
    Grob makes splined shafting and splined bushings for example.
    Cold Rolled Broached Sleeves & Flanged Bushings • US Made | Grob Inc.

    Hoping I won't get banned here, but Thermite once said something to the effect of "Only make what you can't buy, pilgrim."
    I read it as 10,000 pounds(force)-inches aka 10k in-lbs In thermodynamics and statics classes the books used lbf to mean pound force to avoid confusion with lbm pound mass.

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    Ooh-kay.
    "inch pounds" or "foot-pounds" when I came up. In statics class as well. Abbreviated in/ft or Lb/ft.

    O.P., I think you would be well served to see what the splines cost outsourced (by someone in the business of making splined tubes and shafts) and comparing it to your in-house number. If I was a bettin' man, I'd bet on the outsourced being cheaper, esp. after considering machine time (would you have to buy a machine for this operation, or would it slow everything else down using the machines you have?), depreciation on machines, learning curve, etc.

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    Quote Originally Posted by Rudd View Post
    Abbreviated in/ft or Lb/ft.
    I sure hope they didn't teach you that in your statics class. Torque is a force times a distance, not a force divided by a distance.

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    One thing I'd be curious about is shaft/mate compliance. With a grid coupling or other "flexy" union you've not just got a mate, but a way to accommodate misalignment with reasonably low localized wear. Shock loading tolerance can be higher too, as well as potentially having higher torsional capacity with a full diameter shaft and clamp on coupling.

    With a spline, you might have to upsize your basic shaft diameter, and have a better axial alignment control to prevent uneven wearing at the spline mate. Have you calculated these effects and compensated for them? Or is it a small enough issue in your use?

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    Quote Originally Posted by Vitran View Post
    In terms of a solution, I think that idea of getting a custom single tooth broach may be a good way to go. Make a rigid jig to rotate the broach to each of the different splines. There is also using a single tooth cutter and driving the spindle or turret like a shaper. Those are the two leading paths I think could work for me.
    If you want the parts to take about twelve hours apiece to cut and have bad tooth-to-tooth spacing, go for it.

    Otherwise, buy a gear shaper with internal for 5 thou or so or a broach for less, but the broach itself will be a few thou. (The machine is a broach and the cutter is a broach, a bit confusing.)

    Broaching will take about thirty seconds per part, shaping a few minutes. But the shaper is more versatile, if you decide to do 22 teeth instead of 24, it can do that easily. With a broach, what ya bought is what ya got. And if someone forgets to clean the chips out of the gullets, you can lose the whole broach.

    Forget that indexing shit. I've done it on very low quantity jobs with no other alternative and it sucks. Badly.

    But there is a pair of nice Pratt & Whitney slotters on Cregs List, they'd be better than your homemade indexing thingamajig. Cheap, too.

    Or the last alternative is to find a gear or broaching shop near you and send it out. Broaching is pretty cheap if it is a broach they have. You can ask Pioneer Broach in Californee, they have a ton of broaches, but that's a long way away.

    You're in Ontario, I don't know anybody back there but CGC and they do 2 and 3 meter parts, so probly too big for you. If you're designing your own parts, Ash Gear has worn out used broaches for about 4/5 of new. Look through their catalog. I'd buy a new one from China instead, it's cheaper and better.

    Or if you shop it out, ask the shop what they have that's about XYZ diameter, PDQ number of teeth and design to match.

    Do you want involute or straight-sided ? That's another kettle of fish.


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