Beginner milling chuck key question

[HopperParticipant @hopper]

Good result.

One advantage of having the bevel, besides aesthetics, is it eliminates the square shoulder that is a stress concentrator and could conceivably lead to the square shearing off there under King-Kong chuck tightening loads.

[Chris VParticipant @chrisv]

Quick update on the chuck keys, 2.5 finished just need to order some more bar stock for the last handle.

Overall i'm very pleased with the result, certainly far from perfect but they fit, will do the job and look & feel good to me. Thanks all for your help, of course this first M type/mill project has raised more questions to follow separately!

Chris.

[JasonBModerator @jasonb]

You have made a good job of those.

[Chris VParticipant @chrisv]

Thank you Jason, your help was invaluable!

Cheers

Chris.

[Chris VParticipant @chrisv]

Chuck Key Update. I bought another chuck so will need more keys! (-:

But I wasn't happy with how I secured the cross bar to the stem on my first attempts, several centre punch dots didn't seem quite right given the effort (for me) of making the rest of the keys. So I thought I'd utilise for the first time the previous knowledge learned when I enquired about fitting taper pins. This morning I fitted my first 5/32" taper pin.

All went well but of course I have a couple of follow up questions.

When I drilled through I ended up with a burr on the underside. Twiddling a countersink bit didn't remove it entirely so I used a very fine file, which of course marred the otherwise reasonable finish I had. I rubbed it with a little abrasive but the surface was never going to be the same, unless of course I disassembled the key and put it back in the lathe. I didn't think this was wise so its ended up not 100% perfect for a first attempt.

So the question is can I either prevent a burr forming or if not any ideas I could try on the others to clean it off?

I'm well aware its only a chuck key but I'm keen to get what I do as good as I can.

Chris.

[egaParticipant @ega]

Try a sharp triangular scraper for deburring.

[Ian PParticipant @ianp]

I've never crossdrilled chuck keys but usually fitted a grubscrew axially into the main bar which already has a centre holes from turning operations. A dimple in the cross bar and jobs a good-un

Ian P

[Chris VParticipant @chrisv]

Thank you ega. I'm not familiar with metalworking scrapers, would this be used as a kind of countersink to

remove the burr, or pushed across the surface in a similar fashion to a file?

Thanks Ian, yes I did consider a grub screw which surely would have been easier.

But I'm trying to learn some of the traditional basics for my own satisfaction. (-:

Chris.

[Howard LewisParticipant @howardlewis46836]

Following on from Jason's post.

The determining factor is cutting speed. This will depend on the cutter material and the material being cut.

But assuming High Speed Steel, cutting mild or low carbon steel, 100 f p m (25 m p m ) should do the job.

Slower for harder steels, such a Stainless, or Silver Steel. faster for brass, or Aluminium (But Ali does tend to weld itself to the cutting edge )

If your machine is rigid, and can withstand higher speeds, carbide can be run at much higher speeds.

You also need to take into account feed rates. This will depend on the type of cutter used to cut the material. For an End Mill, think in terms of 0.002"/tooth (0.050 mm / tooth ) So a 4 flute End Mill can be fed at twice the rate of a 2 flute Slot Drill, purely because of the number of teeth

The feed rate will be a product of RPM, Type of Cutter and Number of teeth.

So, as an example, a 4 flute End Mill running at 500 rpm on mild steel could be fed at 0.002 x 500 x 4 = 4"/minute, (100 mm / minute ) as a maximum. On the other hand don't let the cutter idle on the work; it will heat up and soften the edge..

H T H

Howard

[Chris VParticipant @chrisv]

Thanks for this Howard, much appreciated! (-:

regards

Chris.

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