Lathe Question

[Mike W1]

Have no knowledge but what I'd like to get done is shorten the shoulder on a Lyman sprue plate cutoff screw to eliminate having to use a spacer washer along with the belleville one. Am guessing it would be a job for a lathe, possibly a miniature one, and from posts on here some of you guys must know how to use machines that I don't have OR know how to run. Want to get some shortened about .040 to .050 inches.
Is that something that can be done? I do know a guy with a lathe but I'm sure it's a full size one.

 

[Ian]

It won't work, a new one will have to be made from scratch. See the smooth shank on the bottom? That's where the lock screw contacts it. Threads would have to be cut away to create a new surface for the lock screw, and the bottom of the screw cut off by the same amount that the shoulder is shortened. There would be about 1.5 threads left on the shank after the modifictaions, and with the back relief of the existing threads, there's no material to cut more.

What's so bad about an extra washer?

 

[Brad]

Almost anything is possible.
I would put a small hunk of steel in the lathe. Drill and tap for the threads on the screw, making hole proper depth to let screw bottom out with head well above surface. Thread in screw tight and use this to hold screw while turning.

Far easier to make little things on a big lathe than big things on a little one

 

[Brad]

It won't work, a new one will have to be made from scratch. See the smooth shank on the bottom? That's where the lock screw contacts it. Threads would have to be cut away to create a new surface for the lock screw, and the bottom of the screw cut off by the same amount that the shoulder is shortened. There would be about 1.5 threads left on the shank after the modifictaions, and with the back relief of the existing threads, there's no material to cut more.

What's so bad about an extra washer?

He does have a good point. Why modify a screw if it won't work? Damn, that Ian is smart.

 

[Ian]

Far easier to make little things on a big lathe than big things on a little one

You's smart too! A pin vise will fit nicely in a 16x60 engine lathe, but you can't turn 6" chromemoly shafts on a benchtop.

I'd volunteer to try and make a couple screws, but I'm up to my arse in rebuilding a 99 Savage right now...figuratively of course....during breaks from baby time. I'm getting better at typing one handed on here and holding her at the same time.

 

[KeithB]

That's one of those parts that's easier to make new than to alter old.

 

[Ian]

That's one of those parts that's easier to make new than to alter old.

Just figuring out how to hold it and indicating it true both directions for cutting the shoulder back would take longer than throwing a rod in the 3-jaw, turning down four steps and a thread relief, spinning some threads, parting it off, turning it around in the chuck, crowning the head, and sawing a slot.

 

[Mike W1]

Well fellas thanks for the very prompt info. Guess it'll be the extra spacer washer. I'm down to 5 moulds and 2 of the 5 use screws with that shorter shoulder. 1 of those I bought around '75, the other a couple years later. Other 3 in the last 15-20 years. Don't know why they couldn't have maintained those dimensions as the newer one's don't seem to be any noticeable improvement.

 

[KeithB]

You hit it exactly Ian.

Why does Lyman do anything?

 

[fiver]

I'm sure they just paid less for the different same style screws.

 

[JSH]

You better check those threads. Lyman is known to use some off the wall thread pitches.

 

[358156 hp]

This is too complicated.

Lyman mould repair kits are only about $10.00 ea, and the pivot screw will match the sprue plate thickness.

 

[KeithB]

Yeah, but will the hole spacing and location match the cavity spacing and location? I've run into problems there also.

 

[fiver]

there is actually 2 rebuild kits for the 2 cavity molds.
they list the one you have to call and specify the second one which has a separate part number and closer hole spacing for the cavity's on the plate.

 

[Pistolero]

I'm thinking that if I put the snout into a collet and locked it down, I could turn back the
shoulder pretty well.

Bill

 

[Eutectic]

Far easier to make little things on a big lathe than big things on a little one

Pretty profound there Brad!

Why just the other day both you and Ian didn't even have a lathe...... I'm betting some sort of milling machine is swimming around in both your heads by now!

How about Lamar???? I haven't heard a single peep about his lathe yet!

Pete

 

[smokeywolf]

I'm betting some sort of milling machine is swimming around in your head by now!

If it isn't it should be.

 

[fiver]

I made up my mind long ago a lathe was not gonna happen here.
I know what would happen if I had a lathe, and I don't have the room [nor the funding] for that to happen.

 

[Ian]

If it isn't it should be.

Took me about two lathe projects to realize how desperately I needed a mill. Just having a lathe is like having only end wrenches and no socket set.

I made up my mind long ago a lathe was not gonna happen here.
I know what would happen if I had a lathe, and I don't have the room [nor the funding] for that to happen.

Took me 30 years to finally get one. If the price of gas ever goes back up, buy the house across the street and move your storage stuff over there. Put a small lathe in the garage.

 

[fiver]

that place doesn't have a garage.
it does have a swimming pool in the basement sometimes though.
it would be easier for me to build a 20x30 shop in my back yard, the bottom half is already split as a separate building lot.
like I said a lathe would equal more money than I'm willing to lay out.