Milling curves

[Clive WoodfordParticipant @clivewoodford40780]

Hi, I’m an absolute beginner and on advice I’ve purchased a Warco 250V lathe and a small Warco 16 mill. I also purchased a Set of Stuart Victoria castings and after some tuition from my CAD engineer son I got on with the model. All has gone well but I’m lost how to mill a semi circle in a piece of steel angle plate that supports the cylinder. The Mill has a DRO fitted but I can’t understand the Chinglish in the manual, if if I could would it help and what’s the best way forward?

Clive

[Clive WoodfordParticipant @clivewoodford40780]

Stuart Victoria build

[Dave HalfordParticipant @davehalford22513]

A heavy duty rotary table would be better something with decent size teeth on the worm and wheel.

[JasonBModerator @jasonb]

The DRO method is probably one of the harder to understand in most instruction book but once you work it out a very smooth curve can be made with a series of overlapping plunge cuts.

Other more traditional methods are to mount the workpiece on a rotary table so that it moves in the required arc around the cutter.

Another method is to use a boring head set to swing the correct radius and plunge that down as the work is moved towards the spindle.

 

Another option is to ask your CAD engineer son to print you off a set of co-ordinates for a series of overlapping holes which is basically what the DRO does inside it's box of tricks.

Failing all those a half round file will probably be just as quick

 

Edited By JasonB on 29/03/2018 19:06:18

Edited By JasonB on 29/03/2018 19:14:31

[SillyOldDufferModerator @sillyoldduffer]

All the small engines I've made were done as described by Jason with a boring head. It's also possible to use a fly cutter in a similar way to cut even larger semi-circles.

Requires patience and you will same a lot of time if you cut out most of the unwanted metal by drilling/cutting/grinding or milling first. Last time I needed a 22mm diameter curve, I got rid of most of the metal by plunging with my largest milling cutter (20mm), then tidied what was left to size with a boring head. With the work horizontal I've also successfully roughed out using smaller cutter to cut out a step profile.

I learned a hard lesson first time I tried this job. When roughing out don't remove too much metal by accident …

Dave

[Clive WoodfordParticipant @clivewoodford40780]

Thanks everyone, I think as I have the DRO I’ll try the arc method – the video makes it all sound quite straightforward. , although I need to get my head round the programming as this is an internal curve.

[blowlampParticipant @blowlamp]

I have a Sinpo DROII 3m console, which is likely to be similar in operation to yours. Here is a cleaned-up version of the manual that I found on the net. It's not a perfect example of clarity, but it is better than the one supplied originally.

Martin.

[Alan VosParticipant @alanvos39612]

Posted by JasonB on 29/03/2018 19:05:25:

Another method is to use a boring head set to swing the correct radius and plunge that down as the work is moved towards the spindle.

I was contemplating that setup recently, but got stuck at how to set the correct radius. How would you do that?

[JasonBModerator @jasonb]

I will either use an edge finder to locate the edge of the work, then move the table until the spindle is the radius away from that edge. You can then set up the boring head and gently rotate it by hand as you adjust the cut radius until it just touches the work, you will now have it set at the correct radius so start cutting and just advance the work into the tool.

Sometimes I will clamp a piece of scrap opposite the face being machined so that the tool cuts both parts, you can then just measure between the two and adjust the boring head until you have the required diameter.

[roy entwistleParticipant @royentwistle24699]

Clive Don't forget that you will need two of these brackets, one for each end of the cylinder

Roy

[Author]

Posts