Drilling specific angles on round stock in mill

[schemer]

I am going to start a new project where I need some exact angles drilled into the circumference of a piece of aluminum 2" in diameter. I understand the part of using an end mill to make a flat, or even drilling the complete hole with one. But the part I am puzzling with in my head is how to set it up for the angles. I don't want to re-tram my mill so that is out. I have a 3-way compound angle vise (https://www.grizzly.com/products/Grizzly-4-Three-Way-Precision-Angle-Vise/T10059) so that may work. But I thought maybe somebody else ran into this before and has an easier way. Like is there a simple formula where I could just shim the aluminum to the correct angle and just use my regular vise? What it the most accurate way to get and measure the angle, say 30 degrees, with what measuring tool? Should a buy an inclinometer and if so, what would be a good one for short pieces, like 2" long?
Thanks,
schemer

 

[rwm]

What you are describing is a sine vise.

That would work and be very precise. You put the appropriate stack of gauge blocks under it to achieve the correct angle.
This is a perfect application for a rotary table with a chuck mounted. Then you only need to find the center once. Your vise should work as long as you recenter after each change of angle. How you approach this depends on the degree of accuracy needed.
Robert

 

[schemer]

What you are describing is a sin vise.
View attachment 335171
That would work and be very precise. You put the appropriate stack of gauge blocks under it to achieve the correct angle.
This is a perfect application for a rotary table with a chuck mounted. Then you only need to find the center once. Your vise should work as long as you recenter after each change of angle. How you approach this depends on the degree of accuracy needed.
Robert

Those are usually pretty small vises. Do they come with gauge blocks? I am making a tungsten sharpener that looks like this:

 

[schemer]

I just watched this video on setting up a sine vise. Looks easy enough but I would have to buy a nice sine vise and gauge blocks. Now I have added this to my "To BUY" list but maybe not for this project. I normally make things I could buy and it always costs more than buying it, but what fun is that?

 

[schemer]

Ok, so I see I can afford a sine vise if I go with a 3" version with a 4"+ opening but I have a question on the gauge blocks. Amazon sells an 81 piece set but will that magically cover any angle or will feeler gauges be involved? Never have owned or used these before.
Thanks

 

[Flyinfool]

What you want is simple.
Use a rotary table with the center line of the part on the axis of table, Have it mounted so that the axis is parallel to the table. Now to get the angle you want just move off center. You will have to do some simple trig to get the position and angle to what you need. Once set up it is just a matter ofmake a hole, turn the part the required degrees for the hole spacing and do the next hole. Be real careful when breaking thru to the inside bore at an angle. Drills and taps do not really like cutting on just one side. You might want to put in the tapped holes before you bore the ID.

Yes you will need to spot to bigger than the thread OD with an end mill and then spot drill then finish drill and tap.

 

[Flyinfool]

Ok, so I see I can afford a sine vise if I go with a 3" version with a 4"+ opening but I have a question on the gauge blocks. Amazon sells an 81 piece set but will that magically cover any angle or will feeler gauges be involved? Never have owned or used these before.
Thanks

Nothing magic, yes that 81 piece set will cover nearly everything from .1000 thick to 4.000 in .0001 increments.

Using the sine block will require a setup for each hole. A LOT more work than a rotary table.

But a sine block and a gauge block set are still nice to have around.

 

[Bob Korves]

The angle needed for your tungsten sharpener is not that critical. You may be over thinking this. As stated by others, a rotary table mounted vertically would certainly do the job. Something like an angle vise would also do adequate work for that job...

 

[schemer]

Thanks for the info Flyinfool. I think I will get the sine vise and the gauge blocks just because I can with my birthday next month. I was thinking of drilling and tapping before boring so you confirmed that. On the rotary table, will that work on a small length part like 2" maximum length without the quill getting in the way?

 

[schemer]

The angle needed for your tungsten fastener is not that critical. You may be over thinking this. As stated by others, a rotary table mounted vertically would certainly do the job. Something like an angle vise would also do adequate work for that job...
View attachment 335174

I have a compound vise as shown in the link on the first post. I have a 10" rotary table that I have never used yet. Maybe a good time to get a hernia and try it out. Or buy a smaller one. Initially I was more worried about achieving the angles think really simplistic like using my regular Kurt vise and some shim under one end but how to measure the angle. I just found this:

4" PRECISION TILTING ROTARY TABLE w. 3"/65mm 3-jaw chuck Part#TTSK-100CK- NEW | eBay

The TTSK series tilting rotary table can be tilted and locked from 0 - 90 degrees any angle. Ideal for machining oblique surface and holes. PRECISION TILTING ROTARY TABLE w. Clamping kit-new w. 3"/65mm 3-jaw self-centering chuck and centering adapter.

www.ebay.com

Don't forget I have a birthday coming soon so I have to buy something!