View Full Version : Turning Question
01-04-2006, 11:06 AM
Ok I will try to explain my question as best that I can. I have an axle set up exactly like the one pictured but it is not true so I want to chuck it in the lathe and true the faces up to the shaft. My question is will the bolt holes that are in it be a problem?
01-04-2006, 11:21 AM
No, it's what is known as an interupted cut. Be sure your setup is rigid and take a minimal cut. The only casualty will be your nerves. It sounds like its beating the macine apart. Usual cutting speed and feed data apply.
BTW I would recommend a HSS bit. Carbide and Inserts don't like impacts.
01-04-2006, 12:04 PM
01-04-2006, 03:29 PM
Your spoiled. :lol: :lol: :lol: :lol:
I'm running this little 12" Atlas/Craftsman with little rigidity. Brazed carbide was a very short lived experiment. A couple of friends with sturdy lathes swear by them. My insert tooling consists of a set of 3/8" square holders with soft headed hold down screws :twisted: and inserts that match that quality. They do a nice job if I need to hog,(hogging is a .050 cut on this thing) but I've knocked enough tips off to shy away for interupted cuts. The only good toolholders I've found for real inserts require a 1" tool holder. My toolholder will only accept 1/2" sq and less.
Most of my turning is 1018 and 1020 because of the limitations of the machine.
Anytime you guys are throwing out a good heavy lathe that isn't huge give me a call. Your only a couple hours down US 24 from here. :D :D
01-04-2006, 05:01 PM
Heck, I'll take huge! I'm working on a 10" Yam (Yamamoto Machine Tool Company). Wanna talk about a joke for rigidity? Wanna talk about gibs in need of adjustment and scary backlash (not very repeatable at that)? It needs to be torn down and adjusted (cleaned, lubed and everything else), but I'm not the only person who uses it.
The lathe has an Aloris-type quick-change toolpost (the PhaseII version of the AXA). Our shop made holders will handle a tool shank just a hair under 3/4". So, I've been buying 3/4" and 1" shank indexable tool holders off ebay for nearly nothing (like 2 brand new Kennametal holders for $12.50!) and milling them down to fit.
The carbide inserts will handle an interrupted cut quite well. However, for some uses, I still like HSS too.
Got to agree that Joe is spoiled :) . Must be nice :lol: . Some of use have to buy this stuff out of our own pockets - HSS starts making a ton of sense :lol: .
01-04-2006, 06:30 PM
There are many different grades of carbide. Some are harder and are good for light finish cuts and get good tool life even in hard material. Some are softer/tougher and are good for roughing forgings etc. They even have some ceramic grades now that can withstand interrupted cuts. Milling grades are usually tougher since by the nature of the process they are always entering and exiting the cut. Some of the tools they make now are pretty amazing. We use a drill made by Iscar called a Chamdrill, the head of the drill is a replaceable carbide tip and the drill body has coolant through. While you can't feed it as fast as some of our other (larger) indexable drills,they are unbeatable for high diameter:depth ratios. We just finished 312 holes .625" dia. X3" deep in HT4140. 1140 rpm and .01" IPR, and the drill head dosen't even look used at all! Only drawback is they are bad expensive and you can only use them in cnc's.
01-04-2006, 09:52 PM
Hey Joe, does that mean you guys are the one's driving up the cost of tooling on eBay? :lol: I've bought a fair amount of tooling that way, simply because the stuff in our machine shop sucks! There aren't even any unchipped inserts!
Guess it's just as well. Went to use the indexable end mill the other day, and our "machinist" had put new inserts in it - 2 TPU322 and 1 TPU321! For those unfamiliar with the terms, the last digit refers to the radius on the tool. The bigger the number, the larger the radius. Why would that make a difference? Well, the smaller radius tool ends up being longer.
Bought 53 RTW-brand C-5 grade TNMA324 inserts for around $20 with shipping a few weeks back, so deals are still out there. Got a Kennametal holder with 5 new inserts for $15, and the previously mentioned pair of holders (without inserts - they use TNMAs :) ) for $12.50.
A bit of time with a catalog from MSC, Travers or J&L will fry your mind with tooling options and specs!
01-05-2006, 08:08 AM
Don't apologize for being spoiled. That's just our envy talking! :lol:
That set of carbide holders is the exact set I have, but mine are 3/8" and take a smaller insert. My new AXA holder will take 1/2" so I've toyed with the idea of a new set. Problem is I've been soooooo disappointed with these. Poor performance, soft holddown screws, etc, etc. I've limited myself to HSS bits. I grind my own GP bits but was given a lifetime of specials by a machinist turned manager that are really works of art.
I may dive into another set of holders or a couple of individual holders eventually, but for what I do the HS is mostly fine. It seems the insertable tools really work well when I need to hog only want to rub the finesse cuts. I get nice fine cuts with my HS. Make any sense?
You know, I like to ***** about the little lathe, but having it is so much better than not having it. Same with my mill/drill. They do what I need. I've seen a lot of beautiful work turned out with a lot less.
01-05-2006, 02:06 PM
Wish I had Ralph's lathe in my garage too :)
Ralph, look around at some of the "high-end" holders on eBay too. As I said, you can buy larger shanks and cut them down. I generally buy 1" shank tooling and cut it to a hair under 3/4" to work with our quick-change setup. Find something that uses TNMA or TNMG inserts and stick to something along the lines of a TNMA-321. A 320, if you can find it, is basically a zero radius tool, the 321 is very workable. The 323s and up require a hogging cut to cover the radius - otherwise you get the chatter that Joe mentioned. A zero radius insert might help that 3/8" shank set of holders you have now - just a thought :)
I am by no means a machinist, but I'm getting plenty of practice and instruction - my current boss spent 31 years as a machinist for Gardner-Denver. He's taught me a lot of the little tricks, and my skills are improving every day!
You can also replace those soft screws with a decent allen bolt, just machine the bottom of the head to match the screw you're replacing.
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