Flywheel recess

I have made a few flywheels so far out of aluminum with not much problem, but to get my flame eater engine going I am making the flywheel out of steel. The problem I am having is cutting the recess, I am using a parting off tool in stages to 3mm deep, but its giving me some concerns. With aluminum its not a problem, how do you make recesses like this on a lathe. I have a rotary table so is the mill the best option.

I've cut a deep and narrow (1" deep by ½" wide) slot in a pulley using the rotary table with a ballnose end mill. However, if you only need to go 3mm then I'd use the lathe. I'd either use left and right handed boring tools, or grind up a round nose HSS tool. The advantages of the ground HSS tool are that you don't have to try and match depth of cut when swapping the hand on the boring tools, and you get a nice radius in the corner.

Andrew

A parting tool doesn't have enough side clearance for this. I ground a special shape tool from HSS with loads of side clearance that is the side nearest to you. It needs to clear the recess. The shape is like a parting tool but twisted anti-clockwise as you look towards the chuck from the tailstaock. You can buy trepanning tools (which I believe is what the operation is called) but they are pricey. Pictures of similar flywheel cutting and tool shape *** HERE ***

Cheers John

A tool shaped like D-bit but with more top-rake works well.

Neil

I dig out as much as I can with an ordinary lathe tool, then take the rest out with a boring bar, to save having a boring bar with the tool on the opposite side for getting at the hub, I move the tool past the hub and reverse the lathe rotation. As I have screw on chucks, I take very small cuts on the reverse cutting, OK so far. Most of my fly wheels are made in 3 pieces, so no recesses.

Ian S C

Edited By Ian S C on 15/10/2016 13:06:14

Something like this, the curve on the outer edge needs to be a smaller dia than the recess so it does not rub. You can also round the corners so it leaves a nice internal fillet if you want it to look like a cast flywheel

and one in action on a 4" bit of cast iron

I found a tool as shown in the diagram and ground a D shape on the end, I also ground a top rake for it, but it did not cut that well. The tool seemed to rub and became quite noise with powder type swarf coming off, so I ground a slight top side rake and found this a little better but could only cut in at a thou, sought of taking my time. When I cut about 15 thou and cut across it was a fine cut and nice and smooth and no problem. I have tried slow speed 100 and found 500 about the best, I have made a recess 3.5mm which is not enough but this one side has taken me over two hours to do. Looking at the photo thats what I would like to achieve, I have made sure that no play on the top slide so every thing is correct, sorry for this basic question, but I am doing this incorrectly.

You probably still don't have the side clearance on teh edge nearest to you.

If anyone is having problems with a cutting tool's clearance, the easiest solution is to mark up the faces of the tools and try to take a cut. The marking fluid will be rubbed off where there is not enough clearance. If it can't be seen make it so it can be.

I ground a "v" shaped tool similar to Jason's but relived both sides. I managed to cut the hub, rim and the back of the recess with it. I chose to use brass though for my vacuum engine flywheel.

I have used a similar tool and technique and yes there a potential clearance issue on the outermost cut. I usually get round this by disturbing nothing but just lifting the cutter well above centreline in the Dickson toolholder.

The cutting geometry might be all wrong but as long as nobody knows, the end result is fine.

Ian P