Lathe turning question (round toolpost)

My lathe has a round toolpost and a couple of lathe bit holders that look like they are for 3/8 inch bits. Maybe I am really wrong, but it
seems like they are not big enough for this large lathe? Am I missing something? Can I use 5/8" bits without the Armstrong tool holder?
Flame away!
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The tool needs to be adjusted to have the cutting tip exactly at the centerline of the work. Hard to do that with square tool bits and no holder.
Bite the bullet and buy a quick change tool post. You will want the 200 or BXA series. Aloris is the top brand, Phase II works well. Wedge holders are better, piston types are fine. Enco and others have regular sales
Part number 505-2172 at www.use-enco.com $120 on sale.
Ignoramus13075 wrote:

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I just bought one today. Thanks.
i

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Iggy,
If you have the cash to buy a BX knock off then by all means you should also get some replacable carbide type holders and inserts... Quality, (not top of the line but made in America) Holders are under $50 each from Enco, and the import inserts are under 2 bucks each.
I'd suggest some C2 (for brass,cast iron) and C5 (for steel) TNMG inserts and 3 holders, an MTENN (thats a "straight" one), and a MTANR and MTANL, those are "sight" and "left" handed.
For under $200 you can have a pretty classy setup :-)
Here's a few Enco part numbers.
these 2 are import and I forget the tip radius.. you can look them up 344-3212 TNMG C2 344-3215 TNMG C5
these are 5/8 shank holders and should fit the BX just dandy fine. 422-2954 MTENN 10-3B 422-2958 MTANR 10-3B 422-2961 MTANL 10-3B
They way cool thing about these is when you break/dull a insert, when you replace it the machine stays in calibration..
As Iggy said... Flame Away.. :-)
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No flames here!
How about the same set of recommendations only for a smaller AXN used on my 10" Logan?
Dave August wrote:

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Roy,
Enco has 1/2 shank tool holders too that take the T*** inserts. The AX takes 1/2 doesn't it?
FYI those holders I spec'ed for Iggy ( and I recently bought for the 5914 and *MY* BX knock off) were manufactured by Dorian and are VERY nice... The Dorian site (www.doriantools.com) lists them for $52 and Enco sold them for $44.... hey that's almost 20% off :-))
STAY AWAY from any of the holders that take the TT inserts ( Enco and others sell sets for SUPER cheap), they are made in India and are pure junk..
Hit the Enco site (www.use-enco.com) and run the numbers I gave Iggy, all the holders are on the same page.
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    Agreed.
    Learning to grind tool bits from HSS blanks is a good thing too, because there will be things which you can't find insert tooling for -- or can't afford for only one or two uses.
    [ ... ]

    [ ... ]

    Yes -- 5/8" shanks are the max size for standard BXA/Series-200 toolpost holders.

    And -- you don't have to purchase a new insert right away. Each insert Of those suggested (negative rake with a chipbreaker groove which makes the effective rake positive) you have three corners, each providing a cutting tip, and you can flip it over and get another three cutting tips if your original ones have just gone dull. If you've crashed and broken them, you will have damaged the other side too, so you can't use the flip side tip.
    And -- for much of your turning, a single holder, the Aloris BXA-16N will hold two inserts at the same height. One is used for normal turning along the length of a workpiece. The other is used (with the holder mounted on the other dovetail) for facing work. And, they will use the same inserts already suggested. This will take the place of two of the three insert shanks suggested, leaving just the straight ahead one (which produces a nice angle for chamfering/deburring the edges of a workpiece.
    So far, I have not found a clone of one of the BXA-16N holders made by anyone else, and have not found the holders on eBay at a reasonable cost (when the eBay price for a used holder is past 80% of the *new* price, I choose to pay the new price, which is what I did with the BXA-16N which I have.
    Eventually, you will want other holders and shanks -- such as ones for threading insert tooling. And the holder which I find nicest for the threading insert tooling is the one which provides an extension, so the shank is well supported while you have enough extension so you have a better chance to thread something supported by a live center without hitting the center's bearing housing with the toolpost's other dovetail.
    Enjoy,         DoN.
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Gotta agree with DoN on the threading tool holder too, I just didn't want to brag/confuse the issue.
I have the "mini-thin" one (Enco part number 359-5020). It's extra long and as DoN points out it makes it nice if you have to hang it out for what ever reason. You can get threading tips and VERY thin groove/cut off tips, my fav for cutting brass tube is the .019 cutter. The tips have 2 cutting edges on either end.
Besides 3 "normal" tool holders I've also have the cutoff blade, the boring bar, the knurling tool which will mount a regular tool holder too but is on the "backside" that I usualy mount a facing tool on, and a genuine BXA-5 #2 morse taper holder which I have yet to find a use for.. LOL.. I'd buy a 16N but it's too much cash, and all these holders came with my BX when I bought the Lathe.
And yes I learned how to hand grind both regular and threading tools from cobalt and use a "rocker" (lantern) tool post and holders in high school, these T*** just make life too easy.... :-)
--.- Dave
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adding my 2 cents - the genuine ALORIS stuff is quite a bit better than the Chinese copies - get a real ALORIS tool post (used if you want to save $) and a couple of BXA-1 and BXA 2 holders. you can get some cheap chinese ones too, but they don't work nearly as well
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I have two high-quality tool holders set up for threading and finishing and several Chinese ones for roughing, left-hand turning, indicating, etc.
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William, being a little pompous aren't we? I have been using the "cheap chinese" on 3 of our bigger lathes here for about 9 years. They still hold less than 0.001" when changing inserts. I can't see how an Aloris could be any more accurate than that.
They are repeatable to within 0.001" when changing tools in the holder. One lathe here does 3 different diameters on a production shaft and the cross slide dial has not moved off a single setting. It must have made 20,000 small shafts in it's time. Sounds accurate enough to me.
If you or anyone else wants to waste money then have at it, but don't knock stuff just because it is not stupidly expensive.
Dave
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I've almost never used bigger than 3/8", and my Reed Prentice has 7-1/2 hp. Get a quick change, one of the best investments I ever made!
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On Sun, 13 Jul 2008 21:20:12 -0500, Ignoramus13075

=========No flames but perhaps some cold water.
The type of work done on the typical home/hobby lathe does not require or justify the jumbo tool bits and inserts used in a heavy machining production environment.
In a production environment, time is money, and a few minutes saved on each part times 5 or 10 thousand parts quickly justifies the more expensive tools/tooling.
In the home/hobby shop, it is very seldom that more than one or two parts are run, thus a few minutes saved is meaningless unless you are really turned by heavy blue chips and lots of smoke from the cutting oil.
The typical hobby/home shop the lathe is either older but won't turn fast enough to fully utilize the more expensive coated carbide tooling, or it is newer and faster, but lighter weight and not rigid enough to fully utilize the more expensive tooling.
Unless you are *WEARING* the tools out it is generally a waste of money to go for the large premium / high-cost tools. In general these tools, while harder and more heat/wear resistant, are also more brittle and subject to chipping and cracking. They are also frequently more susceptible to thermal stress which is a problem with the typical paint brush or drizzle can coolant application in the home shop.
Compare the prices for the 1/4, 3/8 1/2, etc. tools and you can see a fairly steep increase in prices with very little if any additional use/utility.
So unless you are turning full size train wheels or axles, try smaller rather than larger inserts/bits. The smaller brazed carbide tools are cheaper and the smaller HSS blanks are both cheaper and easier to grind. Again unless you are actually wearing the tools out rather than chipping, the premium HSS blanks with 5% or 10% cobalt are simply *MUCH* harder to grind, more expensive and are more brittle. The super premium TanTumg HSS tools are even harder to grind and even more brittle than the 10% cobalt.
Even for Acme threading, a 1/4 square toolbit should cover most home shop requirements, although a 5/16 or 3/8 bit may be handy on occasion. The larger square tool bits do however make fine parallels, and you should have several pairs for set-ups.
If by "round post" you mean the traditional American style lantern tool holder, while these are slower to change out tools, these have turned out enormous amounts of high precession work over the years. I would consider 1/4 square tool holders to fit the lantern style holder. These come in two types, one called "carbide" with no built-in back rake but usable with HSS tools and necessary for threading to get the proper profile even with HSS tooling, and the HSS type with built-in back rake [typically 15 degrees] that simplifies tool bit grinding because you don't need to grind in back rake. I have found the HSS holders to be quite acceptable for use with brazed carbide tools for most home/hobby shop use. For insert carbide tooling the front clearance my be a problem and you may have to use a 0 back rake holder.
Most mill supply stores will have the lathe tool holders but as an example click on http://www.use-enco.com/CGI/INPDFF?PMPAGE6&PARTPG=INLMK32
The key to using these holders is to get the tool set exactly on center and an easy way to do this is to keep a new sharp dead center just for tool setting. Put the dead center in the tail stock and set the lathe tool to just touch the tip of the center. There are also plans [or at least pictures] on the web for tool height gauges. http://www.sherline.com/3009inst.htm http://www.tallgrasstools.com/HeightGage.html http://home.iprimus.com.au/stevor/lathehtgage.htm [about 1/2 way down page]
FWIW -- if you decide to use 1/4 HSS blanks as standard, buy 30 or 40 as it looks like the prices are shooting up like everything else and these are cheaper by the 10 pack. [watch for sales] http://www.use-enco.com/CGI/INSRIT?PMAKA83-5316&PMPXNO9967&PARTPG=INLMK32 http://www.wttool.com/product-exec/product_id/37958/nm/Ground_Square_Tool_Bit for price comparison between sizes see http://www.wttool.com/product-exec/product_id/37985/nm/Ground_Square_Tool_Bit and even http://www.wttool.com/product-exec/product_id/37988/nm/Ground_Square_Tool_Bit
Good luck and let the group know how you make out.
Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
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