Angle blocks

[Mike K]

Feel free to move this.  This is a beginner's effort at making angle blocks.

First off...I got the idea from the Yahoo mini-mill group.  When I saw it I thought it was a great idea, I could use them for various things.  The idea is to create angle blocks based on the two end points of the hypotenuse of a right triangle.  Straightforward trigonometry.  Gotta love spreadsheets!  So you drill one hole, then calculate the X-Y offset of the second hole such that they create the angle you desire.  Here's how it works...



X = The distance between the two holes in X travel.  Pick a number to suit.  Larger will have a smaller machining error.

Let's make X = 0.998".  Put your calculator in degrees mode, punch in "10" (the angle), and TAN, and then multiply by 0.998.  Y travel equals 0.176".

Position one hole somewhere on the plate.  I chose 0.500" in from each side for the four blocks I made (10, 12, 15, 25 deg).  The second hole is then positioned 0.998" over in X travel and 0.176" in Y travel.

I tried it out by cutting up four pieces of scrap aluminum, about 1.5" x 2.0".  I cleaned up the edges and faces and milled them together as one lump:



See, it's really four blocks:



One is setup on parallels for drilling the holes:



One thing I should point out is that the original idea was for a set of blocks where the distance between the two holes (the hypotenuse) was one inch for all of them.  I'd guess this was so that they could all have the final milling done together.  This meant, however, that none of the offsets were in whole thous.  I redid the math so that all of my offsets were in whole thous, which reduced the error to just that of my machine (and setup).  But this also meant that I had to mill each one separately.  Also, I probably should have made two of each at once.

The holes were drilled and reamed 0.25":



Drill rod was inserted into the holes and setup in the vise:



The top is milled off in about ten passes (this is a mini-mill afterall):



Finished product:



Pretty neat idea, I thought.  I'm heading back downstairs to make three other angles.

Mike

[Bernd]

Perfectly fine were it is Mike.

Nice idea using holes like that. Thanks for sharing. 

Bernd

[Mike K]

Thanks, Bernd.

One thing I found out from this project is that my metal protractor isn't very accurate.  The 10 degree block measured 11 degrees on the tool.  I'll probably make a 29.5 deg block with a little lip so I can setup the mini-lathe cross slide for screwcutting.

Mike

[Darren]

Mike,

Not many responses, but I have to say I'm a little lost here. I'm a little short on the what, y's and wherefores....

[John Hill]

Ya not the only one Darren............

[kvom]

Whys:

If you want to mill an angle onto a piece of metal held in the vise, it needs to be tilted at that angle.  So if you have an angle block, you can place it on the bed of the vise and lean the workpiece against it.

Since 30, 60, and 45 are common angles, it's useful to have two metal triangles, one 30-60-90 and the other 45-45-90.

If you need other angles, you can build them using a set of angle blocks.  These are typically precisely ground.  Or you can use a sine block or sine vise which you set with gauge blocks.

I made a couple of the standard blocks at school.  I used the commercial ones to replicate the angles to mill the edges, and then ground them on the surface grinder.

The post shows a way to generate the angles fairly precisely when you don't have a reference.  Just drill the holes at the desired angle relative to the flat base, and then use drill rod to support the piece on the vise jaws before milling.  It's similar to that way you mill the crank webs on Bogs' engine.

[Bernd]

Thanks, Bernd.

One thing I found out from this project is that my metal protractor isn't very accurate.  The 10 degree block measured 11 degrees on the tool.  I'll probably make a 29.5 deg block with a little lip so I can setup the mini-lathe cross slide for screwcutting.

Mike

Now there's a good project to post. Make one and show us how it would be used. It sure would be easier than trying to crane your neck around to read the dial.

Bernd

[Mike K]

Very sorry, guys.  I left out the most important part.  

I've edited the post (starting with the 3rd paragraph) to include it so the information isn't all over the place.

Sorry again.  I guess I was too excited about the results.

Mike

[Darren]

Right, I'm with you now, the how helps a tad too.....

Well that looks simple enough and pretty useful too, thanks...

[Arbalist]

I know this is an old post but this a very useful idea Mike, thanks a lot!