Machining Horizontal Grooves?

[JDLaCoss]

Hi to all!

I'm hoping someone can impart some wisdom on a new guy. I'm trying to machine the cylinders for a radial I found on GrabCad. It's a relatively simple piece, but one part has me stumped. Is there a good/easy way to machine the grooves in the sides? I am working on a benchtop cnc machine with minimal tooling. I thought a woodruff cutter might work, but the piece is about 2.5" tall, and -- while the profile would be easy -- I don't think I can safely get enough reach. A person might be able to do it with the part turned on its side in a rotary table with the right radius, but I haven't had the money to purchase that yet. Any wisdom from the folks that have been doing this a while?

 

[Cogsy]

Thinking out loud here but maybe a slitting saw of the right radius?

 

[Swifty]

You could turn up a disk and silver solder a piece of HSS to it, then grind it to the correct thickness. Mount it on a shank that gives you enough clearance. The HSS will take a red heat and still be ok if you are careful.

Paul.

 

[kvom]

If you can't cut them all with the reach of a Woodruff cutter, cut halfway down and flip the part.

 

[///]

Yeah, slotting/slitting saw would be the go.

Photo found via google, source: http://www.amdengineer.com/machining-the-cylinders-part-2-050114/

 

[Chiptosser]

The slitting blade is the way to go!

 

[xpylonracer]

I like Kvom's suggestion, do half and flip over. To use a slitting saw means getting the exact diameter/thickness or smaller for the correct depth of cut and chordal length.
Emgee

 

[JDLaCoss]

I'll give it a try. I thought slitting saws still had a pretty short arbor (typically). Maybe I just wasn't looking in the right places. Thank you to everyone for all the feedback.

 

[///]

Turn up your own arbor

 

[abby]

JD you do not say what machinery you have but mention a rotary table and do say that you can't afford to spend.
I presume that you have a vertical mill ? so why not make a simple single point cutter the width of the groove .
A broken centre drill through a piece of bar that can be held in your milling chuck will suffice.
Make the cutting edge the same distance from the bar centre as the fin radius.
Mount the job vertically on a bolt through the bore with provision to rotate through 90° x 4.
The rest should need no explanation.

 

[Jon]

You say that you are using a CNC machine. I am assuming it is a mill. You could just lay it in the vise with the cylinder horizontal along the X-axis. Using an endmill of the appropriate diameter, program a g02 or g03, give the Y and Z coordinates with the J and K coordinates and cut your groove. Then move to the new X coordinate and repeat. Using a stop and the back jaw as a reference, it's simple to index to the next side. I am no expert on CNC, but that's just my $0.02. Good luck with it.

Jon

 

[JDLaCoss]

Hi Jon. I have a ProLight 1000 that I refitted to run off LinuxCNC. A really nice unit as far as small mills go, but still just a small mill. I thought about your method, but my thinking was that type of cut leaves the bit perpendicular to the workpiece and will cause thinning at the end of the cut. That said, I decided to modify the cylinder by making it round-ish (more tear drop shaped). That opens the fins to milling exactly like you said and leaves me with the benefit of a unique piece of work.

 

[JDLaCoss]

Abby, I do like your idea of making a custom cutter with the drill rod. I guess I'm so new to this that I hadn't considered tooling that wasn't found in a catalog. (It's ok to roll your eyes ;-) ) Sometimes the simplest solutions are the best. Thanks!

 

[JDLaCoss]

Here is a model of the modified cylinder. I cut the crankcase and one of the basic blocks for the cylinders, then decided I didn't like how chunky it looked. As long I get the order of operations right, I think the I'll like the modified cylinder and it should be pretty easy to machine.