Need Help!- How do I make a circular cut?

[Micro Milling]

I need to cut around a small circle, not make circle as that is easy, but cut around the outside of a circle. I will only cut around a half circle.

Its hard to explain, but bascially I want to make cut that will be rounded, and i need it to be an even cicule.

How would I do this without a cnc machine? Only thing I can think of is a vice that rotates, I'm new to this but I'm not sure if that is the intended purpose of the vice.

Thanks for any help on this.

[modoleinad]

make a trammel. I can send you a pdf if you can't find any info.

[Fastest1]

That would work fine. I am not sure there is a right way. The right way seems to be the one that allows secure holding of the workpiece while cutting it. As long as the dimensions are obtainable and acceptable to you then the method is acceptable. I have seen so many work arounds when people dont have a specific tool/vise/mill/lathe/drill (you get the idea). It is only up to your imagination, there is no 1 or right way as long as safety is still a priority. Youtube is full of machining solutions and most are getting the job done well. A life long machinist watching some of the videos would crack up with laughter at the solutions hobbyists come up with. He would also be amazed at the ingenuity used at times. Watch some of "Simpson36" videos. Cool ideas. Sorry for the rant but via cnc there will be many options. Btw is the vice on a rotary table? How were you going to cut the arc?

[Micro Milling]

I thought I could use one of these, or maybe even rotate a regular vice that can be rotated, I don't have one of those so no sure if they can rotate while everything is clmamped down.

But here is a rotary table.

http://www.littlemachineshop.com/pro...ory=1034788869

I could mount the object in the right distance from the end mill that it will cut a ciruclar cut while rotated. Just take a peice of paper and hold a pen in the center and rotate the paper, it will just make a dot in the center of the page. If you hold the pen towards the edge of the paper and rotate, it will make a ciruclar line.

[Micro Milling]

Hey everone again,

Here is a lock that I would like to make similar cuts to. You can see the circular cut, you can also see that diagnal cut.

Please give me some ideas on how you would make these cuts, and what tools I should use.

Thanks for any help you can offer.

[Fastest1]

How many do you need to make? If only 1, I would do everything manually and slowly. The rotary table would be nice and would make that interior semi circle without a problem. Trying to pivot a vise with the compass technique you were referring to would probably have more play and the finish would be borderline. The diagonal cut could be done easily too while everything was still mounted on the table, just rotate the piece til the diagonal cut will be parallel to the x or y axis and cut a straight line til it intersects with the side and top. However if this was a production piece, then a jig on the table would allow minimal set up time. Hopefully someone else with chime in with a few other ideas.

[CNCRim]

hmmmmmmm without cnc machine... you can make jig and an endmill attach to Demel, it should work.

[Micro Milling]

How is a jig built? Do you mean to build some kind of custom holder that allows the object to be moved in only that direction?

Also did you mean attach to a dremmel?

[sp1nm0nkey]

We need to know your tolerances and what equipment you have available. If you're trying to hit +/- 0.005, use layout die, scribe it, use an optivisor and pretend the mill is an etch-a-sketch. Don't overshoot your scribe marks. If you're not confident enough for that, get it close and sand it to the scribe marks. If you have a DRO, alternatively you could make a list of points that correspond to points along the curve or diagonal, and try and hit each one individually. That's going to give you accuracy within your glass scales or the resolution at which you sample the curve or diagonal, the latter is likely to be much more coarse. If you need +/- 0.001, use a rotary table to do the curve, and for the diagonal, use a rotary table or rotating vice. How many curves are there in the design? If there's one curve, center your stock on center of the curve so you can hit every point and then rotate the stock through the curve when you're ready. If there's multiple curves, center it on one curve, cut, reposition on the center of the other curve, cut.

[sp1nm0nkey]

Looking at the picture, I'd say... etch-a-sketch the hole in the center and the border, and smooth the hole in the center with a die grinder, and use a belt sander to take care of the outside curve.

[HuFlungDung]

I've been machining for 30 years and wouldn't want to try to make that on a manual mill But I'm not a tool maker either.

I'd draw it up correctly and send it to the laser guys to have it cut. You might be surprised how cheap stuff can be lasercut, if you've got sufficient quantities to make the minimum order.

But if you do it manually with a rotary table, I'm sure you'd learn a great deal about using trigonometry and offsets, and coordinate systems.

[CNCRim]

Originally Posted by Micro Milling How is a jig built? Do you mean to build some kind of custom holder that allows the object to be moved in only that direction? Also did you mean attach to a dremmel?

Go to local bookstore and check out some of the hobby woodworking magazine, it will give some ideas what I am talking about. Explain on here will take forever.