Gear cutting with just a slitting saw

[not done it yetParticipant @notdoneityet]

Saw this on Youtube.

Seems to be the ideal answer to those wishing to make the odd gear of any usual type.

**LINK**

[not done it yetParticipant @notdoneityet]

[Michael GilliganParticipant @michaelgilligan61133]

Clever stuff … and nicely demonstrated

MichaelG.

[Alan CharlestonParticipant @alancharleston78882]

Presumably this could be programmed into a cnc mill.

Alan C.

[John HaineParticipant @johnhaine32865]

Indeed it could. The Gearotic package will generate code to do this, though it assumes the use of a standard end mill rather than a saw blade.

[JasonBModerator @jasonb]

Maybe OK for large teeth but typical ME sizes would need a thin and flexible saw.

Would possibly be better with the blank horizontal, drill a hole for each root the mill a radial slot of the same dia to remove most of the waste and then just move it round as he does taking material off the edge of the tooth with the side of the milling cutter, subject to gear thickness

If you have the CNC mill then you just use a ball nose cutter, or CNC cut a HSS single point gear cutter then use that.

[Roger QuaintanceParticipant @rogerquaintance14196]

oh my the time that takes would warrant making correct profile single point flycutter and cut in one pass.

[blowlampParticipant @blowlamp]

I went the whole hog and made a proper gear cutter, although I have used Gearotic to end mill one-offs successfully too.

Gearotic generated the correct tooth profile, which I took into MoI and made the model.

DeskProto then used the resulting STL file in a rotary axis operation to make the part.

It performed very well to make some Myford ML7 bull wheels.

Martin.

[Jon GibbsParticipant @jongibbs59756]

I know this is quite an old thread but I've been after a 12/25 slow feed cluster for my old ML7 for quite some time and too mean to pay the £40 Myford charge for a factory made one or for a gear cutter for that matter.

So, I thought I'd give this method a go for making a 20DP 12 tooth gear out of cast iron on a 5/16" keyed shaft so I can use the 25 tooth gear from the change wheel set. I was pretty hesitant having read Jason's comment but thought the only way to find out for sure was to try it.

The spreadsheet from Andy's YouTube channel has an imperial sheet and a quick hack of the page allowed me to add .050" to the diameters to reduce the undercutting and provide more clearance on the 3/8" shaft. I used a small .032" thick slitting saw which is slightly thicker than the value recommended which would be about 0.63mm. I didn't notice much flexing in the saw since the cuts were pretty light after the first two which excavate the majority of the waste.

Anyway, it seems to have worked well. I now have a gear which meshes well with the larger gear it drives in the chain and I now have a working slow feed.

As mentioned above, it's not the fastest method but it does work even for relatively small gears. It's also obviously very low cost.

Edited By Jon Gibbs on 08/06/2022 18:07:39

[Pete RimmerParticipant @peterimmer30576]

Well done John. The actual correct shift for a 12T 20DP pinion is 0.062" larger in diameter but for a change gear it hardly matters.

[Jon GibbsParticipant @jongibbs59756]

Thanks Pete.

I didn't know about the correct shift .

I just rounded up the dimensions from this thread… **LINK** to add 0.050" extra. But, as you say, it doesn't matter a jot because of the banjo adjustment.

[Pete RimmerParticipant @peterimmer30576]

Posted by Jon Gibbs on 08/06/2022 20:03:11:

Thanks Pete.

I didn't know about the correct shift .

I just rounded up the dimensions from this thread… **LINK** to add 0.050" extra. But, as you say, it doesn't matter a jot because of the banjo adjustment.

John if you look at the table I posted in that link it gives the info for all tooth counts from 10 to 33. You look up the tooth count in the first column (12 in your case). Now take the number in the second column and divide it by he DP (20DP for your Myford). 1.2477"/20 = 0.062385" or 62 thou. Add this to the diameter that you would get from the normal calculation for gear diameter.

[Jon GibbsParticipant @jongibbs59756]

Thanks Pete.

I remember seeing your table now but didn't see the significance – sorry. I was swayed by the discussion about sizing the blank for an extra tooth which obviously adds 0.050" for 20DP.

I'm new to gears and so clearly making it up as I go along

[JasonBModerator @jasonb]

Jon, what diameter was your "small" saw. I imagine the smaller the dia the less likely to flex. You can see the cut faces taper on the video which would be where the saw has flexed.

[Jon GibbsParticipant @jongibbs59756]

Jason, I used a 45mm diameter saw on a 25mm (outer edge) diameter arbor.

So, it was fairly well supported but with 10mm unsupported I'm sure it could still flex.

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