Milling Rite

[pontiac428]

I don't think there's anything actually wrong, here; I think it's just unsightly. But, I can clean that up if I feel like doing so; it would be really easy with a mill...but I guess a file will do the trick.

The threads are sharp like a v- thread, and should be blunt like an acme. Lucky for you, you're a resourceful hobby machinist and you have options. You can buy bronze flanged acme threaded nut blanks if you look hard enough, which is what I'd do, and machine to fit. Or you can go full smurftard and turn your own. It might turn out to be less effort to cut the internal acme than to source a suitable acme nut, but I am a wuss about those kind of deep, precise, and heavy inside thread jobs. I know I should smurf up and grow a pair, it would be good growth opportunity, but sometimes getting a project going means farming out a step or two... Anyhoo, I would not be keen on re-using that pre-worn backlash magnifier based on my presumptive assessment of one cell phone pic in an Internet forum. So there's a pile of salt to take it with.

 

[Ischgl99]

For the nut, just file or grind the sharp part away, it’s just the end of the ACME thread and is the same on new nuts. I’m not sure why yours is bent like that, it’s possible there was a lot of wear on the threads and it rolled that over, but on the nut that came out of my Millrite, that part is sharp as well, just not rolled over. You can screw that on to your leadscrew and see how much play there is and decide if it needs replacing.

 

[Dave Bonzo]

The threads are sharp like a v- thread, and should be blunt like an acme.

I think the internal ones are okay; it's just that outer surface where the thread was really thin that looks deformed...but I can't figure out how it actually got that way without the rest of them being messed up as well. I'll get a picture here, afterwhile; right now I'm trying to figure out how to detach the saddle.

Lucky for you, you're really good at waving your hands and screaming for help, so you have options.

Fixed it for you.

You can buy bronze flanged acme threaded nut blanks if you look hard enough, which is what I'd do, and machine to fit. Or you can go full smurftard and turn your own.

Never go full smurftard.

I don't think I'll have to replace this one, but once it comes out of the kerosene bath in which its currently soaking, I'll know more. I'm surprised that there isn't a replacement part available, though.

It might turn out to be less effort to cut the internal acme than to source a suitable acme nut, but I am a wuss about those kind of deep, precise, and heavy inside thread jobs. I know I should smurf up and grow a pair, it would be good growth opportunity, but sometimes getting a project going means farming out a step or two... Anyhoo, I would not be keen on re-using that pre-worn backlash magnifier based on my presumptive assessment of one cell phone pic in an Internet forum. So there's a pile of salt to take it with.

Let's hope I don't have to go there, at all...but if I do, I'll just do the hand-waving and screaming-for-help thing and give you a growth opportunity involving a deep, heavy and precise inside thread job.

 

[Dave Bonzo]

For the nut, just file or grind the sharp part away, it’s just the end of the ACME thread and is the same on new nuts.

That's kind of what I was thinking.

I’m not sure why yours is bent like that...

Friday afternoon at the factory, usually; I'm new to rebuilding the depths of machine tooling, but definitely experienced with people that just wanted to clock out and get to the pub.

It’s possible there was a lot of wear on the threads and it rolled that over, but on the nut that came out of my Millrite, that part is sharp as well, just not rolled over. You can screw that on to your leadscrew and see how much play there is and decide if it needs replacing.

Good idea; I'm going to clean the leadscrew here in a bit, as well...so I'll check it then.

 

[Ischgl99]

I'm surprised that there isn't a replacement part available, though.

DC Morrison used to sell Burke parts, that’s where I bought my replacement, but it doesn’t look like they make parts any longer. I’m not aware of any other places that make Burke parts, so any replacements for this mill will likely be custom made.

You can contact them and see if they might still have anything available, or possibly a print they could send you so you can see what the original specs are. https://dcmorrison.com/

 

[Dave Bonzo]

Stupid question: the knee comes off by lifting it up vertically, off the elevator screw, yes?

 

[Ischgl99]

I haven’t taken my knee off yet, but I believe that is correct.

 

[Dave Bonzo]

I haven’t taken my knee off yet, but I believe that is correct.

Then it's probably going to stay on; I don't have a safe way to lift it. Hilariously enough, it was really loose; I took the top locking screw out and noticed that it shifted...so I'm not sure that ANY of the gib screws were doing anything to hold it in place.

 

[Ischgl99]

It doesn’t take much to make the knee loose, and if those screws are not adjusted properly, the knee will droop. You’ll want to make sure the knee elevation screw is well lubricated, if it runs dry, you’ll get slip-stick when trying to lower it.

 

[Dave Bonzo]

It doesn’t take much to make the knee loose, and if those screws are not adjusted properly, the knee will droop. You’ll want to make sure the knee elevation screw is well lubricated, if it runs dry, you’ll get slip-stick when trying to lower it.

Yeah, I'm basically pulling them out one at a time, cleaning them, and then reinstalling until they're snug and the knee still moves up and down freely...and that's how I discovered something vaguely unsettling: every second turn of the elevator handle has a location where it wants to stick. It's a very palpable sensation; it's not just dryness. I stuck my head underneath to see if anything obvious was going on, and this is what I found:

Pictured: "Houston, we've had a problem..."




I'm not sure what's happening up there, but I'm pretty sure that brass pin shouldn't be hanging out in midair to that extent. I don't think that's the cause of the sticking/hesitation - which is a heavy and palpable feedback through the elevator mechanism - but it still doesn't look very happy. So, I guess I need to figure out how it all comes loose.

And here's the weird thing; I don't recall the knee doing this before now.