Gear cutting

When Tubal Cain describes the principles of gear cutting, he makes use of a "lathe mandrel". This is a slightly tapered mandrel. Does anyone know where these can be purchased, short of ordering from USA.I have looked at the regular Engineering suppliers,but to no avail.

Try expanding mandrels, available from the likes of Arc Euro, RDG Tools etc.

Or make one.

These are more suited for light work, grinding etc.

Would not fancy using one on things like gear cutting with interrupted cuts.

If you need a mandrel them make one as John says but hold the work with a big washer and nut.

These mandrels used to be made by Jones and Shipman and as JS says they are not really suitable for heavy work. However they are very useful for dealing with jobs that cannot be easily mounted other than buy an existing hole. They have very shallow tapers and so are size specific. The work has to be forced on and off using a mandrel press.

I have some up to 5/8" and would like to get a few bigger ones but I have not found any source of them. They are occasionally advertised on eBay and fetch good prices.

Hi Roger,

As John say, why not make one. I have made my own mandrels for cutting gears, I have tried to attach a photo that show a mandrel I made for cutting some module 1 gears in Delrin. The mandrel is intended to be used between centers.

To make sure that the gear blank doesn't rotate on the mandrel I drilled a 2mm hole in the flange of the mandrel (red arrow) - using the washer you can see in the photo as a drilling jig. I also use the washer to dill a corresponding hole in the gear blank. A short piece of 2mm silver steel prevents the blank from rotating. The left end of the mandrel is threaded and I use the washer and a nut to clamp the blank.

Thor

In my last year at school, we made a hand grinder, that required two gears to be cut, the large one was mounted on a taper mandrel, the small one was integral with the shaft. We made our own mandrels.

For most work requiring a mandrel these days (not gear cutting), I turn a step on the end of a larger bit of shaft, drill and tap the end, put the artical on the mandrel, then bolt a substantial washer on the end of the shaft.

Ian S C

I often make a split mandrel for things like that (assuming a decent sized hole). Make it a close fit, then drill the end and tap with the tip of a taper tap. Slot across, wind in a suitable screw and it grips much better.

Neil

Exactly what I do as well, works very well and gets a good grip on the part.

Steve

I would like to thank everyone who has contributed to this thread. Very interesting.It was not so much about how to do a particular task,but why a product for doing that task is not readily available in UK wheras in USA they are cheap and widely available. Tubal Cain did make the point that when milling or gear cutting using one of these mandrels,because they were mounted against the cutting action,the tendency was to drive the gear further on to the mandrel,thus tightening it further. I take the point of unavailability further, Dave Gingery's book re dividing heads can be obtained in UK at a grossly inflated price , a 20DP,14.5PA,No 4 Involute gear cutter is rarer than hens teeth in UK,but 2 a penny (I exaggerate) in USA. What has happened to the great British engineering tradition ?? I suppose it has moved to Taiwan,China and India. Sorry Rant over

Tracy tools stock that cutter.

I phoned them last week to order two gear cutters,they supplied one but were out of stock with the other and didn't know when new stock would arrive. Same with RDG, 12 weeks until new stock arrives.

Do have a look at Ivan Laws gear cutting book one of the workshop practise series. In it you will find details of how to make an accurate single point cutting tool. I have used involute and single point cutters and the latte does work very well.

Yes but they are a pain to make, I made one and then gave up and bought the next. Ok if you can't buy one though.
Also the bought cutter did a far better job and the DIY cutter....... well lets just say it'll not be getting used again!

Steve