I remove the complete clapper box assembly on my Drummond, for a duty such as this.

I turned up a new spigotted plate and driiled a hole (central, I think), tapped it, and screwed in a cutting tool holder. Works well but is a bit limited to the length of slot.

Clive mentions drilling first, I would agree but I would go much closer to the final size. The bung should ideally be the same material as the workpiece. Fit it flush and centre pop on the joint line. Then drill to close to final size. Maybe 5% under. This takes out nearly 80% of the material. Filing will take out the rest. Although I have shapers, if I only needed one keyway I would do it this way rather than set up to do it on the shaper, which would take longer. Unless it was the one or two sizes that I have already made tooling for of course.

John

Hi Nigel,

There are often posts on here about cutting keyways – and I'm frequently tempted to say "I'd just use a shaper" – but there's not much point if they don't have one. However, in this case, you do – so why not use it?

Don't worry about the cutting edge being under the fulcrum (most of mine are not) and especially not in this case as the clapper will be locked and the tool needs to reach into the hole. Nor do you need to cut on the 'pull' stroke – although some folk seem to prefer this.

I use a simple 'L' shaped holder, which is a bit bendy so only takes light cuts. Make sure the cutting tool has plenty of side clearance. Don't go too deep with relation to the width of the slot. Not in this case – but in larger holes, you can view an internal slot pretty much like an external slot and there is good advice in Delmar about that type of work. If you don't have Delmar yet – then I'd advise downloading it as your shaper reference bible.

You might also have a look through this (rather long & windy) article that has some good ideas about purpose tool holders and set-ups which you may find useful. A simple 'L' shaped tool holder (welded or brazed) will do for a one-off light duty job but if you intend to do a lot of internal slotting then a direct thrust one will be better. On my TUIT list but not got around to making one yet.

Keyway Slotting in the Shaper

Regards,

IanT

I've slotted with the X3 Mill but only in bronze after drilling out most of the waste which worked well but Would not want to do 6mm wide in steel that way. On the VMC it may be possible to raise the table rather than pull down the quill as I had to.

I drive my 1/8" and smaller broaches with my old Narok drill press which seldom gets used for drilling these days. Works OK on steel and CI

Edited By JasonB on 24/11/2020 11:26:31

I have broached a 5/32" wide keyway in a cast iron flywheel using a single edge tool held in the tool post on a "Big Bore" Myford. I tried to cut 0.001" at a time. It was very hard work. I will have to cut a 3/32" wide keyway quite soon and I am not looking forward to it.

Ian Bradley's book "Myford Series 7 Manual" covers cutting an internal keway. He suggests replacing the lead screw on the top slide by a cross head and slide the top slide backwards and forwards by a lever and connecting rod. The lever fulcrum is clamped to the right hand end of the bed. Obviously the tail stock has to be removed.

JA

Edited By JA on 24/11/2020 13:25:27

I have cut internal, and external keyways, in steel, on a ML7, using the Slotting Tool designed by the later Peter Robinson.

Possibly College Engineering Supply still do the casting.

It has since been used, on a riser block, in the larger successor to the Myford.

+1 for drilling a hole to remove much of the metal leaving the tool to just cut out the corners.

On one occasion, a tool was mounted in the Tailstock, and the internal square produced using the Tailstock feed, to rack it to and fro, rotating the work, held in a 4 jaw chuck, for each cut.

An alternative method, might be, like Jason, to use the manual downfeed on a vertical mill to drive the tool through the work, whilst putting on the cut with the table traverse feed.

With a tool of suitable form, and the work on a Rotary Table, it would be possible to cut gears, or splines, in this manner.

Howard

Edited By Howard Lewis on 25/11/2020 12:47:42

Nigel,

When I was making my gearbox, I had a lot of internal keyways to cut and ended up buying a broach. But while researching the different means of machining keyways, I had a look at Stefan Gotteswinter's other video of slotting on the shaper, here.

I didn't go that route, as I said, but did get around to making the tool holder for my little shaper – a motorised Perfecto, like this:

The tool projects from the clapper at a downward angle of 5°, the tool is 12mm in diameter and takes 4 or 5mmØ round high speed steel. It is to a similar design as Stefan's, the beauty of this arrangement being that the back rake is imparted by the down slope of the tool projection. In my case, a previous owner had drilled and tapped a hole in the side of the clapper box, as seen in the photo above, which meant that I could lock the clapper with a suitably sized set screw. The thrust is taken by the enlarged step seen at the join with the clapper box and the tool is retained in the clapper but a couple of grub screws, gripping the rear portion of the tool.

When my current project is complete, I intend trying it out in earnest.

John

Edited to improve clarity – I hope.

Edited By John Hinkley on 26/11/2020 19:38:05

Nigel Graham2,

Look at Joe Pieczinski 's youtube called, "no dividing head, no problem" He makes a lttle disc with a lot of circumferential flats and a lot of holes in diff. nos to accept pins. Clever little job to index a lot of divs. His other youtube videos also very good.

John