Beginner milling chuck key question

To help me set my 4 jaw chuck I need to make a couple of chuck keys. Ive barely used my Amolco mill as yet but would like to make them as aesthetically pleasing as the one pictured above indicated by the pencil. I have a square ER32 collet block so if i can find a suitable length of bar to fit it milling the 4 flats should be ok. I was thinking of milling it with the round bar horizontal.

But its how to add the bevel detail? I could probably make a good mess of it with a file, but was wondering how those with experience would mill the details?

Mill the flats horizontally then set the collet block at 45 degrees in a vice?

Mill it all with the bar vertical & then the details at 45 degrees?

Thanks in advance!

Chris.

If you use a flycutter rather than a milling cutter you can get the chamfer cut at the same time with a suitably shaped cutter. I'm a one key man myself.

Ah thanks for that Jason, I like it. I think I might have a flycutter, though that's a whole new level of scary!

So you mean its akin to grinding a custom cutter for the lathe?

I shall go and find it, think about it, then probably make a simple one for now I think as I'd like to get my lathe set up before I go too deep down that rabbit hole!

Cheers

Chris.

Using a file would be my choice but if you want to mill the chamfers you have stated the method I would use in your post, just do the 4 flats with the flutes and then mount the block at 45 deg and do the chamfers using the end of the cutter. If using a machine with any backlash get the tool positioned so you are not climb milling.

Emgee

Or just use the side of an half inch end mill to give 1/4 in radius. Beware of the cutter rotating or pushing back the stock so do it up tight. Also think of how to jury rig an end stop that lets you position the collet block at teh same location as you rotate it to keep all 4 bevels aligned.

I'm going to be careful not to look at the end of my chuck key until I have forgotten about this thread.

The original was probably made with a tool like this. I turned down the shank to Ø20mm to suit smaller collets.

Martin C

Yes you would need to do a small amount of grinding.

I used to work for a building contractors who had Monument Tools (plumbing tools) as a regular client and remember seeing the machine that they had for making keys with various numbers of flats. The work was held like in a lathe and there was a rotating cutter geared to the spindle so it took X number of cuts for each rotation of the blank

Since you mention holding the work in a square collet block withe the barstock horizontal, why not re-think the relative position of the job to the cutter. I would use the side of an endmill to cut the flats on the 'side' of the work rather than using the endface of the cutter.

The cylindrical shape of the cutter will produce a radius rather than a chamfer, its arguably better from a strength POV but I prefer the appearance anyway.

Ian P

Emgee, thanks yes I might try filing it, then later if it looks rough i can try machining it. Ah yes I was thinking about using the collet nut as the stop but now you mention it i can see that would not work at 45 degrees!

Bazyle, Looking at 1/2" end mills online they all seem to have sharp corners? Maybe you can get them with the rounded corners you suggest, or do you mean I should try to grind the radius myself?

Martin Connelly, would that cut the flats by feeding it into the end of the bar, or just cut the detailing? Whats one of those cutters called?

Right I better get out to the shed!

Many thanks!

Chris.

Too late to edit my last post, but confess I replied without properly reading Bazyle's reply which had already covered what I suggested.

Ian P

Ian P, thank you! My thoughts on this were no I don't understand, repeat, repeat, repeat...ah! b

Brilliant, yes got it! (-:

Thank you.

Yes I see now, didn't understand that bit, I think the nut will now act as a stop for when I turn the part round.

Thank you all

Chris.

This is a Flycut one I just did, found a likely looking toolbit so did not bother to grind anything special.

A few other options would be indexable tool, blunt endmill with corners freehand ground to 45deg or a chamfer mill to do the angle after first machining the flats. Last two could also do it with the work vertical and use it to do the flats and chamfer all at one setting as the sides cut as well as the angled end..

Edited By JasonB on 03/11/2020 13:50:35

Not sure I’d bother myself but you could cut the flats to size first then go round again putting in a radius with a bull nose end mill if you have one. Quite quick and easy and should look ok?

Edit: Reprofiling the corner of an end mill is not a bad idea if you have some spares. They can come in handy from time to time and I usually do this to old (but still sharp) imperial cutters I’m less likely to use. Grinding a tool from scratch specifically for only four cuts makes somewhat less sense.

Edited By Vic on 03/11/2020 15:32:23

keep it simple and do it as Bazyle suggested. That basically how I did my last one - with the side of an end mill but in a dividing head.

Definitely bevelled end mill or slot drill. They produce exceptionally smoothe surfaces and take far longer to blunt.

Also you can mill chuck key ends.

regards Martin

For a simple chuck key, is it worth the bother ?

I made a second key for my 4 jaw chuck, just four flats and a tommybar, simple/effective.

I imagine you could get a sufficiently similar effect shaping the step by passing a suitably angled cutter across the edge in a reciprocating motion.

Hack it out roughly with saw'n file then do the, slow, reciprocating bit on the machine to get them all exactly the same.

Hafta get it right.

If you are the sort of person who likes such things anything more than a thou or two or degree or two error will scream at you every time you pick it up.

Clive

Right then thanks everybody. The photos above show how far I got last night, about 1 hrs worth of milling.

Its a HSS cutter, one I was given, feels sharp but might not be unused. 1600 RPM, as that's what the mill was set at. The material is 16mm dia silver steel, chips are like coarse filings. I was taking off about 8 divisions (8 thou?) at a time. All was going well enough but the further I cut into the bar I'm finding I am having to take finer cuts as the mill seems to protest as I reach the end of my cuts (the radius). On reflection I should have turned the end of the bar down on the lathe to reduce the amount of milling required.

Does the above all look & sound fine?

Chris.

1600 rpm is way too fast for a 16mm (5/8" diameter cutter. It will be losing its cutting edge as you go at that speed, which is why its getting harder going.

BAsic formula for HSS cutter with mild steel material is RPM = 400/diameter in inches. So try more like 600rpm or even a bit slower for silver steel.

You should be able to do it nearly in one cut. Or one roughing cut then a final finishing cut.