[How-To] Cutting a 90° slot/groove in a 1.5" bar.

If you mount the material in a vice at 45 degrees, you have to 'center' the corner by matching 'Z and X axis motion. TIlted head or chamfer only requires moving 1 axis.
 
Thanks Erich, that's exactly why I was thinking of tilting the head. I do have a chamfer cutting tool, I think I'll try that first. It's always nice to know how to do things in other ways though.
 
I did it once by setting up at a 45 in a dividing head. Used a height gauge to scribe the center line. I clocked it in the dividing head by running a height gauge along the line (turn the dividing head to get the line parallel, though it wasn't essential for my project). Eyeballed an end mill to the center line and moved Z down and X in equal amounts. After I had a cut of decent depth, clamp a dowel pin in the "V" and measured from the pin to the edge of the part above and below the pin. Did the trig and changed just the X or Z to get the "V" centered up. Then proceeded moving X and Z equal amounts (pass with X, next pass with Z).

Bruce
 
In 15 years of owning a Bridgeport, I have never had to tilt the head. It’s always been way easier to tilt the part, or clamp it to a tilt table.
Knowing a little trig, at least the basics of sine, cosine and tangent functions seems fundamental to good machining.
And really, in an hour, I believe anyone could learn these functions.
Am I wrong?
 
Just for fun said:
I just happen to have a 90° chamfer; I may try that since I don't have one of the cutters that Dave linked to.
Click to expand...
was that in the stuff that I sent you? Be interesting to see how you get on with it. One thing that I've read is that the tip doesn't like cutting as it's rotating so slowly, so a good solution is to cut a relief slot the full depth of the V and then a little bit more before cutting the V. That way you're only cutting on the sides of the cutter.
 
Winegrower said:
In 15 years of owning a Bridgeport, I have never had to tilt the head. It’s always been way easier to tilt the part, or clamp it to a tilt table.
Knowing a little trig, at least the basics of sine, cosine and tangent functions seems fundamental to good machining.
And really, in an hour, I believe anyone could learn these functions.
Am I wrong?
Click to expand...

I agree, and I am learning.

mattthemuppet2 said:
was that in the stuff that I sent you? Be interesting to see how you get on with it. One thing that I've read is that the tip doesn't like cutting as it's rotating so slowly, so a good solution is to cut a relief slot the full depth of the V and then a little bit more before cutting the V. That way you're only cutting on the sides of the cutter.
Click to expand...

No, I already had one I just didn't think it was designed to cut like that. Now reading your post, I believe my initial thought may have been correct. Thanks for the pro tip on cutting the relief cut.
 
You pretty much got the whole selection of ways to do it. If you go flat and use a countersink or chamfer tool, make a small groove first for the tool point to ride in. The point doesn't want to cut real good and will drag and slow you down. If you go with the angle setup, you can scribe the center line and bring a sharp edge endmill til it touches and then move in and down the same amount. The guys were right that this not a critical design feature. However, with that said, since you are asking how to do this, I would use it as a learning experience. Jo Pi has a half dozen or more videos on finding angles, locating starting points, using toolballs, Trig, etc. I would watch all them first. I would then go for a perfectly centered angle to a specified depth. As stated, it's a machinist jack, just make it look pretty. But, sometime in the future you will have a project that does require precision, so practice on something that doesn't require it. Trig is simple as explained by Jo. A $2 calculator with online tables and math websites will do it all. Once you get used to it, a $6 engineering calculator will work even better. I have two, one at my desk and one in the toolbox.
 
Well, I got it done. I used my 1/2" chamfer tool. It didn't work real well but it worked. I didn't go a 1/4" deep as planned. I just thought it didn't look right, I stopped at an 1/8" deep for the deep cut. I did cut a shallower groove as @Parlo suggested. As mentioned the tip does not like to cut, shallow cuts were the answer.

I thought the groove turned OK for being in mystery metal and using a tool not designed for cutting V grooves. Now on to the rest of the project.

20220801_182430.jpg
 
You must log in or register to reply here.
Back
Top