Millling curve with a boring head

[starr256]

I am trying to make the finger clamp designed by clickspring as show in watch. My quandary is how to cut the curve in the clamp. The video skips over that detail. I am considering using a boring head with the radius fixed and easing in to the location 0.010" deep, backing off, and going down another 0.010". As in all things, I am sure there other methods. Looking for the safest, most accurate and repeatable method.

 

[catsparadise]

Are you thinking of using the boring head like a large milling cutter and milling 10 thou deep and moving x (or y) to produce the cut? I guess it might work - I've never tried. I'd have been tempted to set the boring head to the desired radius, line up the y axis with the centre of the desired arc, use the quill or knee to plunge the cut the full depth, then shift the x axis over 10 thou, plunge and repeat till you've blended the arc in with the straight section. That way the whole final cut gets done in one pass which should give a less steppy finish.

I guess Chris didn't describe how he made it as he probably just had at it with a file, producing an arc to a better tolerance than a mere mortal would with a decent mill!

Rob

 

[RJSakowski]

The curve in the clamp is purely esthetic. It looked like it was done by hand by clickspring. It would function equally well to just run two intersecting straight edges. I would machine the edges with an end mill to produce a natural fillet.

 

[brino]

I just watched both of those Clickspring videos.
Thanks for mentioning it, because I hadn't seen them.

I believe Chris finished all the edges of the clamp on the belt sander and die filer.

-brino

 

[Latinrascalrg1]

Does the clamp have to be an identical match to the clamp in the video, meaning are the dimensions critical to function that I'm not seeing? If not couldn't you simply mill the 2 edges using something like a 1/2" or 3/4" end mill in a 4 part setup (2 per long side)?

Use the vertical cutting surface to mill to the center point of the arch cut then slightly rotate the part to the desired angle and continue to mill to the end of the part. On side 2 setup the part parallel to side 1 and repeat the cut only this time you rotate the part the opposite direction and you should end up with a clamp that looks relatively close to the one in the video.

 

[starr256]

With all my efforts with cutting metal, learning the skills and techniques is the primary focus. Secondary is the functional aspect of the results. Hence, I seem to make things twice, which is OK with me. That is why my original question. I have tried Mr. Catparadise suggestion and find it a worthy one. The results are better than what I was getting. It's a slow and friggin' noisy process though.
Next project is a Die Filer. Next tool purchase is a belt sander. I'm learning...........

 

[TakeDeadAim]

I have had parts that required a similar cut and did it with a boring bar. I used as short a bar as possible and took it in small bites. Your right its a noisy affair, rather like rounding a square or rectangular part in a four jaw on the lathe. Earplugs help. Since my DRO has a radius function it will help guide me cutting a radius, (not like a CNC mind you) but if I go slow it gets me close enough to work it with a file to acceptable finish when I'm done.