Suggestions for drilling a v shape

Hi Guys,

I need to drill a v shape into mild steel for a depthing tool i am making.

I would like the outer diameter to be approx 5mm tapering to a point so the v can hold a variety of arbor diameters when so adjusted.

Any ideas?

regards

Chris

Edited By Chris TickTock on 27/10/2020 17:14:43

Spotting drill

Centre drill

Countersink bit with pilot hole first

D bit

Reground drill bit

Graver

All these will do it for starters

Using a 90 deg c/sink drill 2.5 deep to leave 5mm diam start to taper.

Using a 60 deg centre drill go 4.33 depth to leave the 5 mm diam hole start.

Emgee

If it's just a shallow countersink, the ideas above are fine, but looking at the pic (which isn't easy to make sense of) I'm wondering if you're looking to make a long, tapered hole several diameters deep?

If so, you might have few other options than to make a tapered reamer out of (eg.) silver steel. I'd find that pretty challenging, but clockmakers might not. Probably start the hole by drilling a series of steps with reducing diameters to carefully-controlled depths, then finish ream.

Trying to bore it would be a bit like microsurgery, but there are probably folk on here who could do it?

Edited By Mick B1 on 27/10/2020 19:30:29

Thanks Mick,

I am as yet unsure as to depth but I tend to think the longer the metter interms of stability and diameters covered. Maybe a 60 degree spot drill or graver but still thinking and asking.

Chris

You might also make copper electrode and get it spark eroded. It occurred to me that that's the way the toolroom would've probably done it back in the day around 1980 when I was a tool designer.

I don't hear much about sparking these days, and I've often thought engineering has fashions, same as phone apps and skirt lengths, so perhaps it's out of favour - but looking at the Bay, I see there are spark erosion machines that appear to be comparable in price with a decent hobby mill, and there are companies offering a service to carry out such ops.

First ... I’m surprised by the proposed use of mild steel

However: to address the actual question:

Edited By Michael Gilligan on 27/10/2020 22:28:25

Use a graving tool ? Grind it to any shape you want. As used by watch and clock makers etc.

I don't think you will find a 60deg spotting drill Chris, main reason I put one at the top of the list is that it will leave the smallest diameter at the bottom of the Vee so you can fit a good range of arbors into it. A "Drill mill - Chamfer mill" would work in the same way but also 90deg like the spotting drill

The downside of a centre drill is that your arbor will only sit on the 60deg angled part so you can't go down any smaller than the diameter of the pilot and at 5mm across the Vee a typical pilot diameter would be 1.5-2mm

You could use mild steel if you want an easier to drill material and simply drill and loctite in hardened points at the other end say 3mm dia.

.

Not quite sure, Jason ... but I assume that 5mm would be the outside diameter of the runner, rather than the Vee.

That would be typical of a Clockmaker’s depthing tool, and seems to be what Chris was describing in his opening post.

MiichaelG.

.

https://www.tap-die.com/contents/en-uk/d300_Centre_Drills_1mm_12.5mm.html

Edited By Michael Gilligan on 28/10/2020 08:00:59

We'll have to wait for Chris but I read "outside diameter tapering to a point" to be the OD of the hole probably using 6mm OD rod. Regardless of that any ctr drill will have a pilot that will limit the smallest dia that can be held.

Maybe it's a clock thing but I have not used a depthing tool for years, I tend to find a method to mount one gear in it's position and then hold the other in the mill and run the two together, once happy with position just remove the second gear and form the hole in the part.

.
... neatly tabulated here : **LINK**

https://cuttingtools.ceratizit.com/ie/en/products/10708.html

MichaelG.

Thanks Guys for all posts all noted and appreciated.

I am buying in a 90 degrees spot drill which should do the job. Still chewing over using brass bushes which would allow me to use centre drills with various DIA tapers and end holes, but then this would mean making additional parts and possibly introduce errors. I will see how the centre drill does.

If I only had 1 or 2 tapered holes then maybe making a D drill would be the answer. The issue with making a simple jig to hold anything from under 1mm to 5 or 6mm and over a limited depth of 4 mm is limiting on the tools available off the shelf. From my calculations I expect the 90 degree 6mm centre drill will be acceptable...I will see.

Chris

Make sure you get a spotting drill and not one designed for spot welding - names are confusing.

Gadgetbuilder says he used a countersink.

The drawing for the runners on Colin Walton's depthing tool gives a centre drill 0.093" dia. with a pilot 0.04" dia.