keyway on involute cutter

Must be something with me and tools, when I bought my lathe a pair of internal threading tools seemed like a useful addition.

The tips were brazed directly to the shaft so in theory should thread fairly small internal diameters, when the items arrived they were nothing like the picture, the shaft was bent over 90 degrees and the tips brazed to that. Instead of approx 8 - 10mm your now looking at 20mm +.

Ordered an involute gear cutter, pictures and specs show a keyway, when the item arrived there is no keyway. argghhhh

Seller offered half my money back, but now i need to make an arbour without a keyway and make sure the gear cannot slip. How much pressure does an involute cutter take? Is a keyway essential?

Thanks.

Edited By Dave Smith the 16th on 29/06/2016 17:07:04

Hi Dave,

I have involute cutters bought from a reputable shop and they have a keyway. I have also made my own gear cutters without keyway. I use both types on an arbor without a key, I feed a bit slow I guess and have never had any cutter slip.

Thor

I've never bothered to fit a keyway into my gear cutters when I have used them, seem to work fine.

Hello Dave,

You can cut a keyway in an involute cutter with a square diamond file. It is slow work on HSS, the alternative is to spark erode it instead

Arc Euro sell sets of those files. I have no connection other than being very pleased to resolve just such a problem and open out a small half round keyway on a commercial cutter. Taking very light cuts without a keyway does not actually do the cutter any favours, they are intended to cut to full depth in one pass and will lose their edge if made to work in small bites.

Regards

Brian

You probably want to start buying from a proper tool supplier...............

All my involute gear cutters have keyways, and I always use keys, even though you might get away without it for larger DP, ie, smaller teeth. But then again I drive my cutters fairly hard on rigid machines. Of course Brian is correct, there is no point in taking multiple cuts with involute cutters, it just wears them out and wastes time.

Andrew

Proper supplier, mmm the internal threading tools i bought were from a company mentioned on here quite a bit. not sure if you class them as a proper tool supplier though.

Or are they just a UK branch of a Chinese supermarket with ever changing stock that can vary from week to week?

I need another trip to ARC or an online order for some digital scales i think Tempted by the glass scale kits though.

Thanks.

My one inch horizontal milling shaft does not have a key slot. Presumably this was deemed good enough for the full power of 1HP of the original motor.

Neither do my 250mm circular saw nor my angle grinder. Agreed, it may depend on the contact area and torque, but I doubt the average hobbyist really needs a key, in most situations, for gear cutting.

Select your tools carefully. Most rolson, silverline, black spur (and others) tools are avoided by me, unless they are for a one-off easy duty task. 'Buy cheap, buy twice' is a good maxim to follow.

It might just be an economy measure to make the arbors cheaper? All my arbors, for both vertical and horizontal mills, have keyways. But the horizontal mill is 5hp with a gear box, so high torque when running a typical involute cutter at around 100rpm.

I'd agree wholeheartedly with the maxim about not buying cheap tools; they're a complete waste of money.

Andrew

I think the biggest risk to tooling caused by operating without a driving keyway and relying on the grip from spacer collars alone is to slender cutters, like slitting saws.

If the saw stalls in the cut, but feed continues to be applied, even by hand, the result may well be enough to shatter the cutter from buckling, something it cannot tolerate.

Brian

Apprentices at R - R were taught NEVER to key a Slitting Saw. I narrowly escaped injury when a fellow Apprentice ignored the advice and the Saw shattered! If it jams, the saw just stops rotating. Have NEVER had a Slitting Saw shatter because of a jam up.

I use my Involute Gear Cutters without keys and always cut full depth (d+f) have never had a jam up

Better to slip than buy a replacement for a broken cutter.

Howard

I don't use keys for any of my 1" and 1.25" bore cutters and I've never had a problem but then I don't expect industrial production rates. However, I could forsee a problem if the cutter was fitted in a dirty state and then tightened itself altering the position when gear cutting. Colin

I slot 303 Stainless Steel, .051" wide ( sorry no Metric ) X .373 deep. Broke many, key way or not.

It might just be an economy measure to make the arbors cheaper?

Andrew,

It may not be the original arbor, but is likely. Doubt it was a cheap economy measure, if original, as it is a Centec.