1:10 conical reamer for Neumann Stylus DIY

[farmersplow]

I had the problem of finding a suitable reamer to drill the receptacle for a Neumann stylus into an aluminum or brass part.

The pitch of the cone is 1:20 (on each side). A reamer is then referred to as a taper as 1:10.

Sketch:

Neumann Stylus.png

Neumann Stylus 2.png

In my search I came across a huge number of reamers with a 1:50 taper.
But I could only find 1:10 from a diameter of 3mm (which is too big).
So I need a taper reamer with a pitch of 1:20 with a diameter of 0.8mm (0.0315inch) to at least 1.4mm (0.0552inch).
My inquiry to a tool manufacturer was answered with a cost of EUR 600 and a delivery time of 12 weeks.
Since I'm poor and impatient, I needed my own solution.

After all, all I need to do is drill into soft aluminum and it only needs to be 1.2mm to 1.35mm accurate for the stylus to stick.

I built this construction accordingly.

20211031_112204.jpg

So I firmly mounted a Dremel in a bracket that I can adjust at an angle. An angle can easily be set: a deviation of one cm must be set at 20cm. (or 30cm with 1.5cm deviation or 40cm with 2cm deviation ...).

20211031_112244.jpg

I mounted this construction on a simple 3D milling machine from Proxxon. The Dremel rotates the 2mm drill at about 10.000 rpm. The cutter rotates the grindstone at around 20.000 rpm.
The drill (Dremel) is moved back and forth along the X-axis. Only a small amount of material is removed due to the low feed rate in the Y direction. After five back and forth movements, everything is ready.

20211031_112209.jpg

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20211031_112225.jpg

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20211031_115412.jpg

The 3D (manual) milling cutter costs about 230 euros
The Dremel costs 50 euros
The 2mm drill costs 1 euro.
I have saved EUR 319

P.S .: It works Nice

greetings from Vienna
Thomas

[dmills]

I think you have just reinvented the cylindrical grinder, very cool.
Be careful about clean up, grinding dust is evil and if it gets into the ways will completely ruin any precision that Proxxon ever had.

Regards, Dan.

[farmersplow]

Thanks Dan for the tip!
I try to keep the sanding dust away from the machine as well as from my eyes, nostrils and other inevitable skin wounds.
In this way, the precision of Proxon and myself is largely retained.

greetings from Austria
Thomas

[sifis1983]

Hi,

It's really amazing that you make this with a reamer!

I just 3d print (in aluminum) a torque tube with 1.38mm hole and the 1:20 cone seems that fits well.
Don't test it yet, cause I'm building a new head for it.

What kind of aluminum tube do you use exactly?

check mine below:

aluminum torque tube1.jpg

aluminum torque tube2.jpg

aluminum torque tube3.jpg

[evildrome]

Well done! That is a novel solution to a difficult problem.

Model engineers have the same problem reaming small tapered holes and what they do is to make a " D Bit Reamer ".

https://www.homemodelenginemachinist.com/threads/making-a-tapered-d-bit.23861/

It's usually done on a lathe but there seems no reason you couldn't just do what you did but instead, turn the plain end of the drill into the tapered element.

Then creating the flat would simply be a case of locking the Dremel so it doesn't turn, setting the table parallel & then grinding the flat.

Cheers,

Wilson.

[Phinster]

Hi..you don't happen to make corundum styli with facets for Neumann's by any chance? All we have are Japanese 'Adamants' and they're expensive and not that brilliant.

Thanks for taking the time! Pete

[farmersplow]

Hi..you don't happen to make corundum styli with facets for Neumann's by any chance? All we have are Japanese 'Adamants' and they're expensive and not that brilliant.

Thanks for taking the time! Pete

Unfortunately, no. That is far beyond my capabilities.

[farmersplow]

Hi,

It's really amazing that you make this with a reamer!

I just 3d print (in aluminum) a torque tube with 1.38mm hole and the 1:20 cone seems that fits well.
Don't test it yet, cause I'm building a new head for it.

What kind of aluminum tube do you use exactly?

check mine below:

aluminum torque tube1.jpg
aluminum torque tube2.jpg
aluminum torque tube3.jpg

Aren't you afraid that the stylus will only hold on the outer edge and that it has too little contact surface? I would fear that the stylus would then change the angle (10 °) as soon as (or after some time) the stylus gives way in the bore.
Please tell me your experiences with it.

I think it is possible to press such a small cone into aluminum just by pressure. But I decided on a reamer because I can then finalize the diameter more precisely.
I don't have an aluminum tube directly. More like an aluminum stump. I then drill a 1mm hole (at an angle) into it - that is then rubbed off.

20211109_211550.jpg

Nice greetings from Vienna
Thomas

[farmersplow]

Stylus.png

Here a picture with Stylus

Thomas