Thoughts on my threading...

Carbide is for high surface speeds in a gotta make money production shop. One off, home lathe, slow speed is the domain of HSS tooling. Can carbide work? Yes, but it's an inefficient, money wasting way to do slow speed machining.

https://littlemachineshop.com/reference/cuttingspeeds.php

http://www.carbidedepot.com/formulas-turning.htm

 

^^^
Bullhockey.
Stupid old myth about carbide and manual machines.
What's inefficient and "money wasting" is time spent grinding and honing hss.

Positive rake inserts and many, many types of formulations and profiles make modern carbide very much suitable for manual machines, even smallish ones. Yes, you have to experiment with feeds & speeds which are different but I'll never go back to hss unless i need a special profile.

And that looks like a partial, not full profile insert- thread crests also don't look like they've been topped.

 

SLOW SPEED isn't carbide's realm. Argue with the carbide tool manufacturers or do you know more than them? Plus you can purchase inserts in HSS from Warner Tool.

https://www.arwarnerco.com/60-Degree-Threader-Groover-Right-Hand-p/inserts-60deg-groover-rh.htm

https://www.arwarnerco.com/60-Degree-Threader-Groover-Right-Hand-p/inserts-60deg-groover-rh.htm

 

I would make the move to hs tooling that is razor sharp. The type of insert shown is for cnc lathes. It is not sharp enough, creating to much tool pressure. Which in turn, sets up harmonics/vibration which is shown perfectly in your wavy finish. Just my .02

Paul

 

I also have this threading kit:
https://www.arwarnerco.com/Kit-18-1-2-inch-Threader-NV-p/kit-18.htm

 

I use the same tool, but got tired of the HSS inserts wearing. I use the identical insert with back rake in carbide. The HSS inserts are just as expensive as carbide.

 

Did the same cuts today with HSS and got same results.

Yes, mine is like that.

@
eww1350
, is this where you put the rubber (on top and bottom)?

 

Wouldn’t the angle be 60.5 degrees rather than 59.5?

 

I used Warner...HSS doesn't last as long and I honed them for a while and then went to CARBIDE.

I'm not going to get into a pissing contest over carbide, or over what you say, "manufacturers say".
I use carbide successfully on 3 manual lathes.

I'd bet a chambering job that most riflesmiths that work on manual machines also use carbide.
All I'd need do is go looking through the posts here for pictures.

 

I use carbide too on manual machines but run fast and don't use it for threading tenons or up to a shoulder. It's not made for slow stuff on ANY machine. The question is about using it to do threading tenons or up to a shoulder. Unless you run fast and are quick on the half nut and dials, it's a non starter. I submit that if one is using carbide for threading on a manual machine are they also using carbide chamber reamers? As far as manufacturers, it's common knowledge that carbide should be run with high surface speeds and rpm required should be calculated for the diameter of tool or machine.

 

Dave, I also have a Grizzly lathe getting chatter like your photos with 18 pitch threads.
I was engaging the half nut on #1 or #3 like the thread chart shows. The chatter went away when I only used #1
for half nut engagement. That Chinese lathe must have some error in the way the metric gears convert to inch for threading.
Now I only use #1 for half nut engagement and cutting great looking 18 pitch threads.

Here is a photo of my #3 LH Kennemetal carbide insert running upside down so I can cut away from the shoulder.
You can only do this if your lathe has a cam-lock chuck and not a threaded chuck, so you can run in reverse.
I believe my RPM was around 70 or 115, defiantly not faster than that. "tool wear is directly proportional to RPM" even when using
carbide.

Good luck, hope this helps.

 

The number you engage on should not have anything to do with chatter. Just not really sure the rationale of threading upside down in reverse. Its plain silly if you ask me, lol. I've seen it all, so if it works and your comfortable, go for it.

 

I hate to bust your bubble but I don't use carbide tried it went back to hss an haven't look back LOL P.S. I do use carbide a lot on turning an facing an such.

 

Joe,
Now you peeked my curiosity..lol. Now that you mention it, Threads were much better when I first started out and I was always engaging on #1. As I gained more confidence, I engaged on multiple numbers. Mostly do 24 and 28 pitches. If I remember correctly (and I'm not in shop right now) on those pitches I can engage on any of the numbers. Just for shits and giggles, I'll try that in the morning. Don't know if it makes sense, but I gotta try it!

 

What are the odds that at any given time every gear in the train and every position on the lead-screw and every position on the bed axis will all be lined up the same? Now think about why engaging on the same number on the threading dial should have any effect? Unless you engage it once and never disengage (like for metric threads) the whole alignment of the gear-train on any given pass is a crap-shoot.

 

Well, it was worth a shot. But, of course it made no difference.

 

Those are the exact same pictures as the first post.

 

You are absolutely correct! I screwed up when uploading to my hosting sight. Here are the ones that should have been posted!! Sorry for any confusion.

 

The angle of the compound does get confusing for some. Even though the picture isn't accurately drawn, you should get the point. You want to be 29.5-30° off from having the compound being parallel with the cross slide.

 

Hog
I don't want you have a orgasm looking at all them little curly chips I would like to have one nickel for every barrel that's been threaded with HSS tooling on this machine I would estimate easy 1/4 million barrels still chugging along.