Upshur Flywheel

[Tom GullanParticipant @tomgullan59234]

Hello,

I once again find myself looking for some advice.

I am now at the point where I am about to turn the the two flywheels for my little Upshur IC Engine. The plans call for me to turn my cast iron blanks down to 3 1/2” diameter. Each flywheel has to be 0.562” wide with a 0.625” diameter hub protruding 0.125” on each side. My question is, What would be the best method of removing the material between the hub and the outer edge of the flywheel (this has to be reduced to 0.250". The flywheel should end up looking like the flywheel on a Lister D Type

A friend suggested that I mount each flywheel in a chuck and mill the required material out using a rotary table and an End Mill.

Any advice would be gratefully appreciated.

Regards
Tom

 

Edited By Tom Gullan on 31/08/2017 18:22:47

[Tom GullanParticipant @tomgullan59234]

[JasonBModerator @jasonb]

This is a variation of an operation known as trepanning and a similar tool can be used to make a series of plunge cuts or one with a more rounded end can be run back and forth across the area to be recessed. If your lathe can be reversed without risk of the chuck unscrewing then you can do the final cuts on the hub by working on the far side with the same tool but rotating backwards, the rounded tool is also handy for getting the look of a casting.

You can do similar with a boring bar that can be ramped in towards the rim and then move round to the back to cut in towards the hub.

[Jeff DaymanParticipant @jeffdayman43397]

A drawing of the finished item, and knowing the diameter and with of your stock would help people make meaningful suggestions. Not really knowing enough about what you have, here are a couple of initial thoughts.

If there's enough stock between rim finished dia and stock dia maybe you could screw the blank to a faceplate and turn it in the lathe.

If not, probably you could bore the centre hole and mount the blank on a stub mandrel made from mild steel scrap, a nut holding the blank onto a threaded part of the mandrel, and some sort of keying feature to keep it from turning while the recesses are turned on the lathe. Mandrel could be held in 3 or four jaw chuck on the lathe.

[Tom GullanParticipant @tomgullan59234]

Hello,

Sorry Jeff…. I'm a Driving Examiner not an engineer. I thought I'd given enough information. Thank you for your input, here's the plans I'm working from.

Regards

Tom

 

Edited By Tom Gullan on 31/08/2017 20:50:32

Edited By Tom Gullan on 31/08/2017 20:50:47

[JasonBModerator @jasonb]

Can be done as I said, that's a 100mm bit of cast iron in the photo much the same as you have to start with. Drill the six holes last.

This is a pic of a boring bar being used to cut the step in teh rim, move the tool outwards to make the cut.

Edited By JasonB on 31/08/2017 21:03:32

[Anonymous]

I have cut a recess using the rotary table and a ballnose cutter, but it is time consuming. I'd only use it for deep recesses, 1" deep and ½" wide in this case:

For the flywheels in question I'd use a trepanning tool, as illustrated by JasonB or, if you have them, RH and LH boring bars in alternating sequence. If nothing else it will be much easier to get a good finish.

Andrew

Andrew

[Ian S CParticipant @iansc]

You can use left and right boring bars, or depending on how your chuck is fitted to the lathe, you can push the normal type boring bar past centre, and reverse the lathe rotation and do it that way, that's what I do(very carefully with a screw on chuck).

Ian S C

[Martin ConnellyParticipant @martinconnelly55370]

I think Tom's issue here is how do you get the boring tool in deep enough to start with when there is a hub not a hole in the centre. Using a boring bar as shown in JasonB's picture would require a lot of cutting with the tool being fed in at a shallow angle and regularly swapping from left hand tool to right hand tool. I think the earlier JasonB post regarding trepanning is what is required by Tom, even if it is only enough to get a boring bar in to finish the machining.

I have used a 6mm button insert in a similar way to JasonB with his rounded trepanning tool. The bottom of the holder needed a little bit of adjustment with the grinder to ensure suitable clearance but otherwise it was straight forward.

RDG sell a suitable button tool. I don't know what size tooling you can use but this is for an 8mm shank tool.

**LINK**

Martin C

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