Hand Slotter.

[Michael G]

Rather than brass grub screws, how about a little disc of brass in front of a steel grub screw?

Michael

[BaronJ]

Rather than brass grub screws, how about a little disc of brass in front of a steel grub screw?

Michael

Hi Michael,

Thanks for the suggestion ! Yes I could do that. I have a hollow punch that will make 5 mm diameter discs. Though I do have a short length of 6 mm diameter brass bar that I could turn plugs from.

I mentioned the brass grub screws simply because they were brass and loose in the bottom of a cardboard box that originally had an old style "Wylex" consumer unit in it. They are about 12 mm long and the threads on them look like 2BA, so they probably are from this electrical item.

At the moment I'm busy making the bits for the pivot and lever to move the ram in and out.

[BaronJ]

Hi Guys,

I got a little further on with my hand slotter.

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I've got the handle done and made the pivot pins. The bar for the handle is a 13" piece of 13 mm silver steel that someone at some time has heat shrunk a plastic handle onto. The pivot pins are 6 mm silver steel cut to size and hardened. The one driving the ram is secured by a 2BA grub screw bearing on a flat filed into it. I used a 12 mm length of 12 mm round bar with a 6 mm hole drilled through as a spacer for the end of the two 6 mm X 12 mm flat bars securing the handle. The round bar for the handle is drilled and threaded for M5 screws. I used countersunk hex screws to secure one side plate and used nuts to secure the other side.

More later.

[BaronJ]

Hi Guys,

I've finished the hand slotter today. Got the holes drilled and threaded in the top plate for the adjusting screws and the locknuts.

These are the final photographs. All I need to do now is test it out.

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Thanks for looking.

[Anorak Bob]

Looks good BaronJ.

I am keen to hear about how it performs.

Bob.

[BaronJ]

Hi Bob,

Yes I would like to put it to work ! I've a 4 mm slot to put into this gear hub for my MK2 mill table traverse. So as soon as I can get a new piece of 4 mm square HSS tool steel I'll get on with it. I've lost the original piece that I used when slotting the original gear hub using the lathe saddle. I haven't a clue what I've done with it. It should be in the tin with the other tool steel but it isn't.

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New gear hub to be slotted with a 4 mm keyway.

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Original MK1 gear hub and gear that I slotted 4 mm.

Ah well ! Later !

[oohsam]

wow.
Some of the work you guys do, leaves my jaw dropped.

Excellent stuff.

[pipeclay]

Hope your able to pick it up, dribbling is such a distraction.

[BaronJ]

Hi Guys,

I finally got my new piece of 4 mm square tool steel. Dammed expensive ! Still for a one off plus postage & packing...

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This is the 4 mm tool steel. as you can see its "Osbourne" branded and came in that nice little red plastic box.

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I didn't take any pictures whilst I was making the broach. Its intended to fit into the slotter ram and hold the tool bit in the slot.
The material is 10 mm diameter high lead content free machining steel. Its 90 mm long with a 65 mm X 4 mm slot machined centrally down the length. A 3.2 mm hole was drilled and threaded M4 to fit an allen hex grub screw 25 mm from the business end.
The other end was turned down to 7 mm diameter to fit the slotter ram. The red handle screw driver is a 2 mm hex allen driver. This fits the grub screw.

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The above three pictures show the broach with the tool bit in place and the allen driver in position just to stop it from rolling over.
The next picture shows the tool bit extended slightly by the grub screw. The last picture shows the method of using a coil spring to retain the tool bit and create a force that returns it into the slot. I actually machined the slot 4.25 mm deep to make sure that the tool bit was just below the surface of the bar. The scratches you see are where I stoned off the haridge on the slot edges and the screw hole. I ran a counter sink on the inside to deburr the hole after threading it.

All I need to do now is to sharpen the tool bit and test it.

PS. I still haven't found the original piece of 4 mm square tool bit !

[BaronJ]

Hi Guys,

Moving on from the last post, I've finally got round to slotting the brass bush using the hand slotter and broach.

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This is the setup on the lathe with the quick change tool post, the hand slotter with the broach fitted all mounted on the cross slide.
I've learnt a lot just doing this setup. With the work piece clamped in the chuck jaws, the lathe spindle being locked so that it can't rotate, the slotter has to be adjusted for hight and the tool post angle set to be accurately in line with the bore of the workpiece.
It took some fiddling about to get it all in line and then when you have and start to lock things up you find that its moved.
I ended up locking the saddle, the top slide and the cross slide in addition to the QCTP. Then I had to take the hand slotter off because the nuts holding the handle fouled the top of the top slide and turn it over 180 so the nuts were on top. It actually took far longer to get it all set up than it did to do the actual keyway in the brass bush.

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These four pictures show the broach fully inserted into the brass bush and fully out. You can see the allen screwdriver that I used to adjust the tool bit in the left hand ones and the slightly extended tool bit in the one on the right. At this point I had cut a key way about 1 mm deep. The bubble at the bottom of the work piece is a drop of oil that I put on the broach to lubricate its movement.

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The pictures above are shots of the finished keyway. The tiny steps on the edges are where I've given it a rub with a file to remove any burrs and to ease the fit. The slot is a very tight fit on the key, I'd already cleaned the burrs off the key when fitting the original brass bush, but this keyway is a fraction tighter.

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The final result... A perfect fit, with no play and no slop ! I now need to re-assemble the gear and it ready to go.

Thanks Guys ! Your comments are appreciated.

[Bryan]

Ok I get it now. Interesting approach BJ, and very well done. I think the way you've retained, adjusted and retracted the cutter is ingenious. Had you seen this idea somewhere or is it original? I've never used broaches but this is different from how I thought they worked.

[BaronJ]

Ok I get it now. Interesting approach BJ, and very well done. I think the way you've retained, adjusted and retracted the cutter is ingenious. Had you seen this idea somewhere or is it original? I've never used broaches but this is different from how I thought they worked.

Hi Bryan,

Thank you for your kind comments.

I've probably seen the idea somewhere and its stuck in the grey matter ! I've seen springs used in various odd ways so doing this to retain and control the tool bit doesn't seem unusual to me. It seemed logical to give the tool bit something to push against rather than trying to apply force from the lathe cross slide with an unsupported tool like I did originally and moving the saddle in and out to cut the keyway.

If I was doing it again I would use the drill press and have everything in a straight line. The twisting forces on the tool post were far more than I would like to have.

[Ueee]

Like Bryan i had NFI until you showed it in use. A far better idea than relying on the rigidity of the lathe and tool.
I have seen plans for a "slowpoke" broach, a single toothed broach and wedge that works much like a normal broach but is much slower. Next time i need a keyway i know what i'll be doing. I may cheat and find an elastic band to hold the HSS in place though.

Cheers, and well done!
Ew

[BaronJ]

Hi Ueee,

It hadn't occurred to me until you mentioned rubber band ! I have one of those "Hellerman" rubber sleeve kits. It has several sizes of rubber sleeve that you expand with a three legged tool. It's used to finish off the ends of electrical cables and the like. I could have used a sleeve to do the same as the spring and it would have been a lot easier too. The problem with springs is the ends perforate the fingers when you are trying to unwind them and get them onto the mandrel. Otherwise they work just fine as retainers.

I still haven't come across the original bit of 4 mm square tool steel. Mice ! I'm sure of it

[Steamwhisperer]

Hi Baron,
I want to come and live at your place. I have been doing this stuff for over 35 years now and even after seeing the slotter I doubt I would have come up with that idea of adjusting the HSS for cutting keyways.
I like Ewans idea of the rubber retainer.
If you are worried about the twisting forces on the toolpost, could you bring the tailstock up against it maybe with a special attachment inserted if the quill is in the way.
Just thinking but feel free to tell me I'm an idiot.
Loving your threads.

Phil