Using a vertical slotter attachment to make a male spline

[minimutly]

The job is to make an oversized mini primary gear, part of which as many know is the clutch spline. My vertical mill has a slotting attachment which doesn't have a clapper, in other words if the tool doesn't cut cleanly it will drag on the job on the return stroke. I've done very little with this, mostly due to not having a cutting tool, but the tool will need form grinding, unless by some miracle I can get one in a standard form. Does it need the clapper?
I'm all for trying to see what works, but if anyone has any pointers I would appreciate it. I fully expect one or two will suggest broaching, which is how this is done at the factory, but simply I don't have the capability to make such a thing.

 

[minimutly]

Here’s a mini primary gear:-

And so, I’ve been thinking, could I cut the splines with a gear cutter, shaped suitably?

 

[minimutly]

I like the idea more than slotting, and the witness marks on the used gear say that I might have the meat, as long as the margin is shared with the seal surface…
So does anyone have an en40 or other suitable stock, 80mm or so?
@pressbrake1 - got anything?

 

[gaz1]

id say you was better using a vertical head for doing that piece as its too close to the material infront of it

if you want to use gear cutters then using smaller ones will get you closer

used to show the smallness of them

 

[Agroshield]

If you want to use gear cutters then using smaller ones will get you closer

The diameter of the cutter is determined to some extent by the diameter of the arbor that turns it. Most commercial cutters are 1" bore (sometimes 1 1/4").

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What is the OD of the seal surface compared to the OD of the spline teeth? If the difference is enough, you would not need to worry about cutting into the seal part as you could shrink fit a sleeve or use a speedisleeve after cutting the gear. Bung up any gaps with JB Weld.

As you suggest, have a look at the female part and see just how deeply the splines engage. From the shiney bits on the old gear, there seems to be a reasonable amount of unused spline outboard of those marks.

If it is tight, so that a full-depth spline is not possible right to the needed position, countersinking the female part to a minimal extent could get you out of trouble.

I suspect the original may have been made on a Fellows gear shaper, which is indeed a vertical slotter-type machine.

 

[minimutly]

Speedysleeve, now that's a thought...Will see if I need it, but good to know it's an option. The small cutters I have that are suitable for grinding are inch ID and 3/4, the smallest one has the biggest id, so no brainer which to use.
There is a redundant fellows gear cutter not far from me, might be for sale soon, I'm not sure I want another rabbit hole to go down though. It's a few Tonnes, and right now I don't have room for it either.

 

[Martin Hocking]

Does the bit need to be heat treated afterwards?

 

[gaz1]

you could make the gear cutter out of solid carbide and go smaller

 

[minimutly]

Does the bit need to be heat treated afterwards?

Well the gears (not the splines) are the main drive from the engine to the gearbox, they are to be straight cut, but yes, they will need to be heat treated, which is another can of metallurgy worms.

 

[Martin Hocking]

Well the gears (not the splines) are the main drive from the engine to the gearbox, they are to be straight cut, but yes, they will need to be heat treated, which is another can of metallurgy worms.

I’m just trying to get my head around what needs making.

It seems to me that if the part needs heat treatment and the associated post heat treatment machining, maybe you’d be better off getting someone to make it for you.

I don’t want to be a Debbie downer, you like a challenge and I enjoy watching you tackle them. But if you need to take it somewhere to be properly heat treated and they handle the corrective gear grinding or whatever and then you take the bit home and correct the splines and bore. Seeing as the place you take it to would probably be somewhere that makes gears it might become slightly farcical or at least a bit of a faff.

It’s very out of character for me to try and be sensible so I’ll go back to making crap jokes instead.

 

[Agroshield]

FWIW, a spline probably has tighter engineering requirements to function well than a gear.

Grinding an involute cutter to the correct profile will be extremely difficult. It is a multi-tooth cutter, where every tooth has to be identical, both sides symmetrical and every tooth needing relief.

If I were to attempt this, I would gash the splines with anything and then make a (single tooth) flycutter to finish them. Starting with a square piece of HSS, you are only grinding one tooth, it will be easier to add relief and easier to keep symmetrical.

 

[minimutly]

I’m just trying to get my head around what needs making.

It seems to me that if the part needs heat treatment and the associated post heat treatment machining, maybe you’d be better off getting someone to make it for you.

I don’t want to be a Debbie downer, you like a challenge and I enjoy watching you tackle them. But if you need to take it somewhere to be properly heat treated and they handle the corrective gear grinding or whatever and then you take the bit home and correct the splines and bore. Seeing as the place you take it to would probably be somewhere that makes gears it might become slightly farcical or at least a bit of a faff.

It’s very out of character for me to try and be sensible so I’ll go back to making crap jokes instead.

Lol, Debbie downer...
I get your point though, and it is a good one, shape changing during hardening and tempering is something I'm not exactly an expert on, but that doesn't mean I shouldn't learn. There is a locallish guy who makes gears, I think I might give him a ring.

 

[minimutly]

FWIW, a spline probably has tighter engineering requirements to function well than a gear.

Grinding an involute cutter to the correct profile will be extremely difficult. It is a multi-tooth cutter, where every tooth has to be identical, both sides symmetrical and every tooth needing relief.

If I were to attempt this, I would gash the splines with anything and then make a (single tooth) flycutter to finish them. Starting with a square piece of HSS, you are only grinding one tooth, it will be easier to add relief and easier to keep symmetrical.

This is something I know a bit about, having bought and adapted a Quorn tool and cutter grinder to modify an existing cutter (with correct forms and reliefs for all teeth) to make a helical steering rack pinion (non standard cutter needed).
I'm no expert, but what's the point having a shed full of machines if not to use them.

 

[Martin Hocking]

I think this sort of stuff really embodies the spirit of the forum, excellent have a go attitude @minimutly.

Mind you if there’s no point in having a shed full machines and not using them, then I’m going to have to reassess my life choices!