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Lathe tool holder bit hole angle?

Turnaround

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#1
This question has to show what little I know, sorry for its kindergarden tech level. Years age, to assemble my retirement play shop, I bought a new 14 x 40 Harbor Freight lathe, round column, belt drive drill mill, and a bunch of "car body" fabricator sheet metal tools. Now retired, its time to make stuff. I bought about twenty Armstrong (and others) lathe tool holder, and a gang of Ebay, already ground tool bits from 1/4" up to gnormous. Problem is nothing works. My tool holders mostly have the bit's holes leaving at an up hill angle, which, when added to the relief angle under the cutting edge of all my ground bits, just too great to work. I have to wedge the tool holder down hill at ridiculous angles just to get a sharp edge against the c/l of the stock. It looks like I need tool holders that have their cutting bit holes horizontal, not up hill. What in the world are all my uphill bit tool holders for? And where can I get horizonal tool holders?


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RandyM

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#2
Please post pictures of your set up it would be of great value to answer your questions.
 

Charles Spencer

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#3
Please post pictures of your set up it would be of great value to answer your questions.
Sure would. Could be the lantern tool post is too small, the rocker is incorrect, etc.

A quick solution would seem to be to grind the tool bits so that the relief angle is correct.
 

wa5cab

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#4
Turnaround,

It is my understanding that the reason for the design of the Armstrong style tool holders was to provide top rake with little or no grinding on the top of the cutter. Which is the hardest surface to grind without grinding your finger tips. From your description of the problem, I surmise that all of the pre-ground cutters that you've acquired were ground for use in either a 4-way turret or in a quick change tool post holder, both of which hold cutters horizontally. So your solution, rather than regrinding all of your cutters, is to acquire one or the other.

Between the two types of tool holder (turret and QCTP), given today's availability of cheap chinese QCTP's, that's what I would go with. 35+ years ago when I bought my lathe, the QCTP I bought after a week of fighting with the lantern type with the Armstrong style holders cost me the better part of a week's salary. Today, the numerical amount of dollars is about the same. So they're nearly dirt cheap by comparison.

With a 14X40 lathe, you will probably need the BXA size (from smallest up, they come in 0XA, AXA, BXA, CXA and maybe larger). The so-called complete kits (which are the cheapest way to acquire the start of a set) come with one only of each of the more common tool holder types. Be sure that you buy several extra of the Turning and Facing holders (may be called #201 or just #1). and a couple of extra Turning, Facing and Boring holders (#202 or #2). The reason is that any given turning job may require more than one cutter. If you only have one turning holder, every time you need to change cutters you have to get out the Allen wrench, remove the first cutter, install the second, and get it on center. Which takes several minutes instead of just lifting one holder off and dropping the next one on. At last count, I had 13 #1 and 4 #2 holders, most with a cutter in them, aligned and ready to go.

And if you ever decide to go with replaceable carbide inserts instead of HSS, get a #16 holder that holds inserts oriented such that they can turn to a shoulder (at least one that I've seen can't). They are pricey but It's my most commonly used holder.
 

Charles Spencer

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#5
Today, the numerical amount of dollars is about the same. So they're nearly dirt cheap
Ha! Reminds me that I told a younger guy that a cross peen hammer I had cost me $9.00 over forty years ago. I explained that was two hours gross pay for me as I was making $4.50 per hour. And I was making twice the minimum wage.

I agree that getting a QCTP would be much easier than regrinding your tool bits. Since you're likely to get one sooner or later it would also be easier than grinding them again to fit it.
 

ELHEAD

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#6
Ha! Reminds me that I told a younger guy that a cross peen hammer I had cost me $9.00 over forty years ago. I explained that was two hours gross pay for me as I was making $4.50 per hour. And I was making twice the minimum wage.

I agree that getting a QCTP would be much easier than regrinding your tool bits. Since you're likely to get one sooner or later it would also be easier than grinding them again to fit it.
And you still will need to learn to properly grind and set your bits to cut efficiently
 

Bob Korves

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#8
I agree with Robert's recommendation of a QCTP. I also recommend you keep your lantern stuff. Once in a while, they can get into a tight space that your other tools cannot.
 

willthedancer

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#9
The flat orientation tool shanks were for shapers and brazed carbide bits.

As said above, the angle buys you less grinding to get back rake on the tool. New bits are cut off at an angle to save grinding on the front clearance. That leaves you touching the front up, grinding side clearance and side rake.

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RJSakowski

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#10
The later edition of South Bend's "How to Run a Lathe" has a detailed description of the use of an Armstrong tool holder. I don't know what edition I have as the cover and front piece is long gone but I would guess that it is similar to the 1942 edition which is available as a reproduction for around$5 on Amazon.

IMO, the Armstrong tool holders have one advantage. They can get into tighter spaces than other types. To do so, though, they sacrifice rigidity. They are more difficult to set up as every time a tool holder is removed, it must be readjusted for proper cutting. Since going to to a QCTP, my Armstrong tool holder gathers dust in the tool box.
 

wa5cab

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#11
One other reason not to get rid of at least the lantern tool post, rockers, etc., is that you may come across a specialty tool that only fits the lantern. Like a nicely made ball turner that I bought last year.
 

Turnaround

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#12
Well thank you all. I scrounged around all my stash and found I guess what you call a foir way turret. Problem then was its slot amd three clamping screws would only accept an inch and an eighth tool holder, while my 20 or so antique tool holders are all just shy of an inch and a half. I milled one of the four sides to 1.520" and the horizontal tool holder with a factory ground carbide 3/8" bit is dead nuts on the work's centerline. Yes, there is joy in North Carolina tonight. Thanks again yo'all.
 

Reeltor

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#14
My initial thought was the same as Kernbigo's. Do you have the rocker for your lantern tool post? If so you shouldn't have any trouble setting the Armstrong style HSS bit holder level allowing the built in angle of the holder set your top rake. Either that or the Lantern style tool post is not the correct size for your lathe.

You may have the rocker in a pile of parts and didn't think it was of any importance or what it was for. I just took a quick look at eBay and saw that more than half the lantern tool posts being sold didn't have the required rocker. They are often separated from the tool post.

I see that you have found a 4-way post to use, and that will get you making chips. I've always preferred the lantern over the 4-way and now a QCTP over the lantern.

I was always told the only stupid question is the one not asked, and your question is neither stupid or in any way "kindergarten level"
 

Turnaround

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#15
The mounting hole in my carriage for the lantern limits the diameter of the lantern body, my lantern looks to me like its probably for a smaller lathe. I had considered making a longer lantern body to gain tool holder height, but had not done that because my latest acquisitions of a couple hundred dollars worth of antique Armstrong tool holders are both too wide and too tall to fit through the slot in my lantern. Yeah, now I know (thanks to you guys) I could have bought a "B" or "C" series quick change holder.

The "tuition to the school of hard knocks just has to be paid" is all.


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Turnaround

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#16
By the way, no one talks well of the Harbor Freight stuff, but it was within the budget, whereas a good lathe would not have been doable. I did a lathe job for my farmer buddy that proved to me the cheapoo lathe was capable of better work than my skill level. I cut a full 40" piece of 2" CRS down to 1 1/2", and only had two thousands taper from headstock to tailstock. I could probably loosen the tail stock and move it over, but its questionable whether I could get more dimension accuracy (and probably lose what I have now).


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Turnaround

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#17
That 40" piece was cut several Summers ago and was probably not down to 1 1/2" (which could have been bought), but was to some size to become an spindle replacement for a piece of farm equipment, that only had to be accurate to about an 1/8"


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wa5cab

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#18
The 4-way Turret tool holder that I was thinking of would have held your 3/8" or 1/2" square cutters directly (just as the AXA or BXA holders do). However, no reason that someone couldn't have built one to hold the Armstrong style cutter holders. I've just never actually seen one.
 

Turnaround

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#19
I am calling it a turret. Not necessarily the correct terminology. Here is a dark photo. Any way, it works and I can use the gang of Armstrong tool holders. By the way, after reading about speeds and feeds, I tried different speeds and got some really nice (to me) finishes. Who knew? IMG_1494.JPG
 

darkzero

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#20
Does your tool bit sit on spindle centerline with that set up?
 

Turnaround

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#21
Does your tool bit sit on spindle centerline with that set up?
Yes as to the cutting edge of most of my second hand tool bits sitting on the work's c/l. But, I have to use straight tool holders like a shaper uses, rather than angled tool holders like other people have for their lathes. Some one posted about putting a feeler gauge between the bit and the work to see if the cutting tip was on center line or not. That revelation was like a magic statement, and me doing that was life changing. Thanks to whomever originally said it.


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Bob Korves

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#22
Yes as to the cutting edge of most of my second hand tool bits sitting on the work's c/l. But, I have to use straight tool holders like a shaper uses, rather than angled tool holders like other people have for their lathes. Some one posted about putting a feeler gauge between the bit and the work to see if the cutting tip was on center line or not. That revelation was like a magic statement, and me doing that was life changing. Thanks to whomever originally said it.
I think it was me, but I actually use a 6" pocket rule typically, saves a trip to the tool box...
 
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