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View Full Version : Need some basic help milling an angle....

cuemaker
01-27-2015, 09:53 AM
I need to mill a 60 degree angle on a piece of square stock that is 2" and 5" long. The angle will run length ways..

I have nothing in terms of tooling for angles. I do have a BP, Kurt vise etc.

What is a simple way to do this?

Please know before you answer, I am NOT a machinist, I suck at math and I can follow detailed instructions.

I have spent 30mins watching various videos online..but its not coming together for me.

Thanks

PixMan
01-27-2015, 10:08 AM
I can't see how you'd get a 30º or a 60º angle the full length of 5" on a 2" square piece because it's too steep an angle for that thickness and length.

Do you have a protractor of any kind? That's all you need to set the part in your Kurt vise at whatever angle you want. It's just a matter of having three hands (or two hands and an elbow, knee, head) to hold the workpiece, the protractor and close the vise.

loose nut
01-27-2015, 10:22 AM
Drawings of what you want to do would help.

What level of accuracy do you need? arc seconds or plus or minus a couple of degrees. This is important. it determines the methods you can use.

If accuracy isn't to important them you could lay it out with Dykem and scribe a line at the required angle using a protractor etc. and set it in the vise. For higher accuracy you would need angle blocks to set it in the vise and for really high accuracy gauge blocks and a sine bar or equivelent.

Once we know what you need it will be easier to say how you can do it.

TGTool
01-27-2015, 11:25 AM
Actually I think Cuemaker's problem isn't trivial. If it were a short piece I'd pinch it in the vise between the jaws and use angle blocks or a protractor to set the angle. There are still some sticky points about making sure that what needs to be cut off is above the vise and that the part is parallel and not cocked a little in the jaws.

Since his part is 5 inches long and his vise jaws may not open that far this gets a little trickier. If the part were in the vise with the 5" dimension running transversely then he's got the corners of the part held in the vise jaws which isn't very secure, particularly if he's removing a lot of stock.

In my shop I've got a vise that can be set at an angle but the jaws are only 2-1/2" or so which means at least half the part is hanging out, again a suboptimal setup.

Without knowing more about what he's got to work with I'd think about this. Make two small angle plates with a notch at the lower end so the stock will sit securely. Also make two toe clamps if required that can mount in the T-slots. Clamp a parallel or barstock in one T-slot for a backer, set the workpiece on the angle blocks, press it up against the backer and grip it with the toe clamps. If using a large milling cutter or flycutter, make sure that the pressure of the cut is against the backer bar.

SGW
01-27-2015, 12:43 PM
Assuming the block is exactly 5" long, if you set it in your vise with one end 2.5" higher than the other it will be at a 30 degree angle.

elf
01-27-2015, 01:04 PM
The OP didn't say the angle had to run the full length of the 5" side, just that it was lengthwise.

vincemulhollon
01-27-2015, 01:14 PM
Three off the wall ideas that could be expanded on.

Luckily 60 degree dovetail cutters are off the shelf and cheap, you might have one laying around. I'm not suggesting milling the whole surface (that would be pretty crazy) but indicate the work perfectly flat and use the cutter to chop a perfect 60 degree, maybe tenth of inch "nick" across it, and then remount and indicate off the milled angle to remount it to the table at a perfect 60 degrees (or as perfect as the cutter was ground and as perfect as you can indicate off the dovetail). So if you're indicated in to less than a thousandth over a tenth of an inch slot, then over an inch you're probably good to a hundredth. Cutting forces might fling the thing across the shop best be careful.

My other crazy off the wall idea is you got a BP bridgeport lathe I'm guessing and you could play similar games with the lathe to create the 60 degree angle. I guess if you did the math and cut some tapers, or cone line things, with certain length and diameters to make two round spike shaped spacers under the work (which will be a lot of fun to clamp..)

You could turn the work into something like a wanna-be sine bar itself without too much work.

Hard to guess the accuracy and how much you wanna spend.

Brian H.
01-27-2015, 02:51 PM
If the part looks like what I think, why not just rotate the vise 90 so the length of the stock runs along the Y axis, set the part up on parallels, then tilt the head over 30 degrees? That way, you get either 30 degrees with the side of an end mill, or 60 degrees with the end. If the angle has to go from corner to corner of the stock, can you add a couple of threaded holes to the bottom and bolt the part to some sort of riser block?

-Brian

photomankc
01-27-2015, 03:21 PM
I can't see how you'd get a 30º or a 60º angle the full length of 5" on a 2" square piece because it's too steep an angle for that thickness and length.

Do you have a protractor of any kind? That's all you need to set the part in your Kurt vise at whatever angle you want. It's just a matter of having three hands (or two hands and an elbow, knee, head) to hold the workpiece, the protractor and close the vise.

I'm having the same issue here. 2" square solid stock 5" long with a 60 degree taper cut down the length seems like it's going to run through the thickness before the end of the length of stock is reached (I think like 3.5").

My usual routine when I didn't want to break out the trig book (and before CNC) was to just draw it up and use the CAD to figure what the thickness of the wedge will be at two points Usually the max thickness and mid-point. Using that data I'd clamp right to the mill table on some sacrificial material. With the CAD data I could calculate how much I needed to kick one end of the stock forward in Y to produce the needed angle by cutting it along the X axis. I'd do this using a *dial* indicator on the head to tap the part into alignment with that angle over the x travel. It's one of those things that is 10 times harder to explain than to do. This assumes that exacting accuracy is not needed.

Now clamp it down on sacrificial material and cut it along the X axis. This should result in the desired angle being cut into the part as I advance the Y forward. I usually did this with a scribed line on the part to indicate when to stop advancing the Y. Accurately measuring an angled surface is another barrel of fun. I avoided needing angles as much as possible.

One of the great joys of CNC is rarely needing to futz with this kind of stuff anymore.

ETA:
(slaps forehead) AAAhhhhhh, I see. So we are cutting off a corner of the 2" square along the length of the stock instead. Makes more sense now. My take would be to rotate the head and use an end mill to cut a cradle for the stock into two riser blocks at the needed angle. Leave some extra stock at the ends of the part and use that extra to clamp it into the cradles. Now it's just a regular milling job. When done, load it in the vise and remove the clamping stock.

A couple of these guys can be real handy cause I HATE tilting my mill head:

cuemaker
01-27-2015, 04:04 PM
You all are helpfull.. I had to work hard to understand some it..

So I am thinking this will help me in many ways... especially visualize how to solve the problem

http://i201.photobucket.com/albums/aa129/xringx/71A1ZpYt9rL_SL1500__zps5786bd83.jpg (http://s201.photobucket.com/user/xringx/media/71A1ZpYt9rL_SL1500__zps5786bd83.jpg.html)

I can see show a 2" block wont do the job... might end up with a 1.5" long block in the end (or whatever the math works out to be) ... but I have plenty of other scraps to work with...

Accuracy.. minimal is needed..

With the above tool, I just can clamp stuff up and have a go at it. Plus the tool looks very handy.

Kiwi
01-27-2015, 04:45 PM
if your tolerance is not so fine ? how about one of those cheaper Chinese angle vices ? if it will fit 2"X 2" square stock I would think you will be cutting into the vice at 60 deg ? if so you may have to buy or fabricate a angle plate to clamp it to

Lew Hartswick
01-27-2015, 05:45 PM
Need a sketch and the thickness of the piece. Then is the Kurt a 6" one or smaller.
Questions like this need complete info.
...lew...

metalmagpie
01-27-2015, 10:12 PM
I had to machine a precision angle once, starting with a rectangular solid. What I did after some thought was carefully locate the part, then drilled and reamed two holes using the mill's DRO. Then I pressed in two pins. Finally, I opened the vise jaws enough so the part could slide down but not the pins. I basically hung the part from the tops of the vise jaws by the pins, then carefully tightened the vise making sure the pins still touched the tops of the vise jaws. When the part was solidly clamped, I just milled straight across. The angle came out plenty close enough for the girls I run with. :-)

Of course, you have to be able to figure out two hole locations that form the correct angle ..

metalmagpie