How to make a neat shoulder on lathe?

[paul]

The problem I've found with 'hacksaw and face' method is the small amount left to grip in the chuck; for example today I made a simple crank for my tiny engine and the finished thickness is only 4mm which makes it difficult to set in the jaws accurately whilst leaving enough sticking out to actually face! (I had about 6mm to face down to 4mm). It also makes protecting the work very fiddly!

Still, it worked a treat I also learnt a valuable lesson...drill and tap the two holes in the crank first as it's the most difficult bit to get spot on - on the first attempt I spent a fair bit of time machining to size first which was completely wasted when I bugggered up the drilling!

[SteveW]

Paul,

REALITY CHECK ON... Its just a simple fly wheel!

Why do you really want a sharp corner between the boss and the face of the wheel? Unless you use a very sharp pointed tool you won't get one. If you do use a pointed tool it'll be very difficult to get a decent surface finish.

Going for a more rounded point with top rake suited to parallel and facing you can tidy up a roughed out shape with one final light slow and careful cut in which ever direction suits.

If you can lock the saddle and set the top slide to cut parallel (or perhaps a nice taper) you can achieve a fairly precise cut with just the knobs on the saddle.

If you want to get really clever and save weight while maximising the fly effect try going for a concave face on both faces (an 'E' section both sides) of the fly wheel. Yes its a load more tricky but it looks great and puts the major mass out near the edge. It'll also look great if the top is curved and safer if there are no sharp corners, it's all too temping to test the torque and risk a cut on any sharp edges.

[davidimurray]

Remember , sharp corners = stress raisers whcih could lead to a crack starting.

Cheers

Dave

[steamjohn248]

Paul,

Try heavy feeds, plenty of oil, lock the saddle, and moderate speed. Above all listen to the tool and watch the chip curling off the tool, if it stops coming out of the cut in long even "catherine wheels" you are about to have a smash, back out quickly.

Feed the tool in again gently until you have knocked off the hard lump of chip that had started the heating and jamming proccess. then go into the cut again as before.

I' m not an engineer or a turner, I've simply learned the hard way by smashing up lots of parting tools. Nowadays following the above rules I rarely have a problem though I still prefer not to auto feed.

Like most things listyen to all the various advice, practice, and get the hang of it.

Steamjohn

[paul]

Cheers chaps! SteveW: as the flywheel is less than an inch I think I'll give the E-section a miss until I've got more experience!

[SteveW]

Paul,

JFDI, see elsewhere if you need an explanation.

If you don't push your experience a bit you won't learn. The more screw-ups you make and recover from the more you'll learn. It's how the rest of us got here. Just think safety first.

At one inch diameter you could almost afford to make it in brass. At that size have you considered how you're going to fix it to the shaft. What exactly are you making?

Maybe as a new start-up your scrap bin is empty. That was my problem when I started. I had any amount of odd electronic bits but no odd bits of metal. Save your pennies and get to one of the up-coming MEXs and look out for the alleged bargain bundles of metal. You're going to need odd bits for future projects and rescue missions.

[paul]

Steve, the scrap box is growing considerably - I've remade most things at least once and some considerably more!

It's for a small engine from Stan Bray's 'Making Simple Model Steam Engines'. I'll fasten it with a grub screw.

Any idea where I can find a list of upcoming exhibitions BTW?

[SteveW]

Paul,(All)

The next MEX that I know about is the "London Model Engineering Exhibition" in the Great Hall Alexandra Palace 19th - 21st January 2007.

The usual Model Engineer MEX just after Christmas got shifted into the future.

Both would be a long way from sunny Staffordshire, its over 2-1/2 hours from me.

[paul]

Cheers Steve - looks like I missed the Midlands show....

EDIT: Flywheel completed except for tapped hole for grub screw! The shoulder is not bad either!

[paul]

Now I've finished this I'm thinking about 'recessing' one face (the 'plain' side not the side with the boss). I guess it would need a boring tool to do it properly but I don't have one. I practiced on some scrap with various tools but the edges of the 'bore' were angled rather than perpendicular to the face.... thinking.

[John Lee]

stevew said:

Paul,(All)

The next MEX that I know about is the "London Model Engineering Exhibition" in the Great Hall Alexandra Palace 19th - 21st January 2007.

The usual Model Engineer MEX just after Christmas got shifted into the future.

Both would be a long way from sunny Staffordshire, its over 2-1/2 hours from me.

A long way?? hmm I live in Yorkshire. If I make the effort and it does not surpass the show in Harrogate ( land of my birth) I might be a bit antsy....

[SteveW]

John,

A ride out in the fresh air will do you good. Blow out all that good clean Yorkshire air and get a bit of soot in them lungs and maybe spend some of that hard earned money you've got stuffed in that old mattress.

Only kidding.