+- MetalworkingFun Forum (http://www.metalworkingfun.com)
+-- Forum: Machining (http://www.metalworkingfun.com/forum-5.html)
+--- Forum: General Metalworking Discussion (http://www.metalworkingfun.com/forum-6.html)
+--- Thread: Thoughts About Small Lathe Tool Holders, Part 1 (/thread-3668.html)
Pages:
1
2
Thoughts About Small Lathe Tool Holders, Part 1 - randyc - 08-19-2017
One of my lathes is a small Austrian-made Emco-Maier 8 x 18. It’s a remarkably rigid machine, short and stout, capable of work that many medium size lathes cannot duplicate. But it has limitations, small work envelope, no QC gear box and non-optimum toolpost..
This lathe had been lightly used when I bought it nearly thirty years ago and it was equipped with a four-way tool post. I’m going to start this thread by noting that I have much fondness for both the four-way tool post and the Armstrong tool system, also known as the American tool system.
I have an inexpensive Aloris-Dorian-style QCTP mounted on the larger lathe and it mostly works just fine but the Armstrong system – properly deployed – in my opinion can be the best combination of versatility and rigidity for one-off work. Further comments expanding this opinion will follow below.
But let’s first get back to the four-way tool holder on the small lathe. Since I purchased the machine in 1980, rarely was the four-way tool holder removed except to mount a shop-made boring bar.
For demonstration purposes, here’s a comparison of the boring holder compared to the QCTP boring bar holder, note the difference in tool overhang..
Boring bar is ¾ diameter steel holding a 1/2 shank C2/C6 carbide boring tool or ¼ HSS cutting tool in 1/2 adapter
[attachment=14839]
[attachment=14830]
[attachment=14831]
Let’s acknowledge that boring usually entails a fairly shallow DOC so rigidity may be of lesser concern but the above is a useful illustration of how the QCTP may fall short in rigidity - and the example applies to any tool installed in the QCTP holder to a greater or lesser degree.
The Armstrong system, if it is used casually and without much thought, will be even worse.
Some ten or twelve years ago, I decided to make a few simple tool holders with much better performance than the original four way tool holder.
I made the tool holders shown below which work quite well. The height of the tool holders and the slot depths were cut to the correct depth so that the tips of cutting tools were on center when the tool holder was mounted to the compound slide. There is no tool post, each tool holder is mounted directly to the compound slide.
I made holders for three commonly used cutting tools, 3/8 square HSS tool, a knurling holder and a 3/32 holder for a parting blade. (BTW, the tool overhangs are NOT typical, just posed for the photo !)
[attachment=14832]
[attachment=14833]
These are about as sturdy as a tool holder can be for a small lathe. They mount at a near-optimum location using the same mounting stud as the four way tool holder. Although I don’t use these holders routinely, they are handy for special needs, notably heavy cutting, including single-pointing large threads.
But why not just use the Aloris-style, like everyone else ?
Small lathes must employ every trick one can devise to improve rigidity. QCTP designs are highly convenient and fairly repeatable (the “real” ones are VERY precise) but they are, arguably, the second worst tool post in common hobbyist use for rigidity.
This is mainly due to the distance from the mounting stud to the actual cutting edge of the tool. It’s quite a long way, relatively speaking, and the tool is pretty much just hangin’ in mid-air. That distance creates a cantilevered load that tends to lift and tilt both the compound slide AND the cross slide, a condition that can lead to chatter.
[attachment=14834]
Any tool holder will exhibit similar behavior but most, due to the shorter distance from tool tip to mounting location, have less leverage and hence less cross slide loading. A method that keeps the cutting tool as near the center of the cross slide as possible will generally be the best one.
There are special cases and conditions, of course. A configuration used for heavy industrial turning at Westinghouse Marine Division while I was employed there, was to mount the cutting tool upside down and run the lathe in reverse.
This will also cause the cross slide to lift (compound slides were rarely mounted) but the force tends to push the cross slide dovetails more tightly together rather than apart, which is far better for preventing chatter.
A variation is the rear-mounted tool post (on the opposite side of the carriage from the normal tool post) with upside down tool which accomplishes the same effect to a degree. This configuration allows the lathe to be operated in the forward direction. (An obvious advantage is that the two tool posts – one on each side of the carriage - can be used simultaneously to perform different operations.)
Returning to the topic of the four way tool post, parting operations were sometimes uncomfortable on the Emco-Maier. Depicted below is the original, still in use, four-way tool holder. It is normally loaded with a cut-off blade, a sharp HSS right hand turning tool and a carbide insert tool holder.
One station is left vacant for special needs like a small boring tool. All cutting tools are held in shop-made holders fabricated so that the installed cutter is positioned at the correct height. Tools may be removed, sharpened and replaced without re-positioning provided that the cutting edge height is not reduced. (This has not been a problem so far.)
[attachment=14835]
The further left corner (closest to headstock) of the toolpost bears the load from the cutting process. Like QCTP tool holders, that corner was unsupported and just hangin’ out in space. By tightening the front grub screw, one of the two that clamp the cutting tool, it was observed that the corner deflected under modest pressure.
Although this wouldn’t seem to be a major problem, it occurred to me that if the cutting force of the parting tool could be directed straight down at the cross slide rather than behaving as a lever and minimizing the tool post deflection, the lathe would be WAY happier. A further advantage is that any flexibility in the compound slide is no longer a problem.
A fifteen minute chore justified this premise. I made a steel post to support the “weak” corner of the four-way tool holder – the point of maximum cutting load. The post is threaded into a tapped hole on the cross-slide. (I should note that I keep my compound slides more or less permanently angled at 30 degrees, which determined the location of the post.)
[attachment=14836]
Compound slide retracted and tool post rotated a bit for a different view:
[attachment=14837]
And with the support unscrewed when the compound rest needs to be advanced or rotated::
[attachment=14838]
(continued in Part 2)
Part 2 - randyc - 08-19-2017
After adding the support post described previously, parting became totally free of drama and deep DOC’s when turning or facing became commonplace using sharp HSS tools. This is the 8 inch Emco-Maeir taking a .250 DOC at .007 IPR without cutting fluid, reducing a one inch diameter steel shaft to ½ inch in one pass - no chattering, nice finish:
[attachment=14840]
This improvement, although intended for the four-way tool post, might suggest improvements to other cutting tool systems, possibly even the QCTP.
At the risk of causing controversy, it is my personal opinion that the most common QC tool systems used by hobbyists, although convenient, are not a particularly sturdy method of holding cutting tools.
Having said that, generally hobbyists are not particularly concerned with removing a lot of material quickly. After all, the faster metal is removed, the faster the fun is done
The Aloris-Dorian-style system was designed for production usage and reasonable cutting loads, the type of tasks that most of us will never be required to perform. If removing truly massive amounts of metal in an industrial environment (e.g. my previous comment about Westinghouse Marine Division), one will not find either a QCTP or a four-way, although the tool room lathes are almost certain to have them.
I'm going to diverge momentarily for entertainment purposes - machine tool porn. One of the many styles of large lathes that were typical at Westinghouse is shown below. It’s difficult to discern but if you look closely near the headstock end, you will see the lathe operator standing on the carriage !
I seem to recall a couple of these large lathes with TWO carriages and seats mounted on each. A machinist was seated on each traveling carriage, monitoring the operation and making adjustments. The tailstock dead center had to be re-adjusted often to accommodate thermal expansion of the workpiece.
[attachment=14841]
In days of yore, most intermediate-size American lathes were equipped with a lantern/rocker tool post and the Armstrong (or American) system of cutting tool holders. Four way tool posts were preferred by our British cousins by this time although many large four ways had a rocker for adjusting cutting tool height, just like the lantern.
[attachment=14842]
[attachment=14843]
For the hobbyist, there are many advantages to the Armstrong system:
- Small cutting tools are easily held – small HSS tools are inexpensive and, more importantly, much easier and faster to sharpen.
- There is an Armstrong tool holder for just about any situation
- Tools usually can be sharpened while secured in the holder (no burnt fingers)
- Simple and quick to orient the tool and set it on center
- Top rake doesn’t have to be ground on the tool, as it may on QC and four way cutting tools; the Armstrong holders are angled to the approximate required top rake.
- Above all, the system is very universal
- Inexperienced operators may have trouble grinding and adjusting the tool properly
- Probably the least rigid of any system in common use in many setups (note the tool overhang in above photo of the Armstrong tool holder)
- Unsuitable for production rates where multiple operations must be performed on a single workpiece, e.g. turning, threading, facing
[attachment=14844]
[attachment=14845]
Any operation that can be performed with a QCTP system can be performed with the above method, with more rigidity. In fact, the complete Armstrong tool system can sometimes be more rigid than a QCTP when it is adjusted properly (cutting tool located as close to the lantern as possible)
Perhaps a minor disadvantage of both the QCTP and the four way tool posts is the inability to turn small diameter balls or small radius convex/concave shapes. In the past, cranks, knobs, levers and so forth were gracefully shaped, in the manner of wooden colonial table legs, for example.
These shapes were quite easily turned by adjusting the compound slide appropriately, loosening the compound locking bolts, locking the carriage and slowly rotating the compound by hand. These are a few parts that I made using this technique:
Jeweler’s chasing hammer
[attachment=14846]
Crank handle
[attachment=14847]
Ball turning
[attachment=14848]
The ability to turn small radii requires that the cutting tool be adjusted very close to the rotation axis of the compound rest pivot point. The configurations of both QCTP and four way tool holders preclude this – the cutting tool is too far from the pivot point of the compound rest. The smallest convex or concave shape these tool holders can produce is on the order of a two or three inch radius.
I suppose that this is the reason ball-turning projects are so popular on hobby forums. It’s possible that most hobbyists haven’t even considered using the compound rest for this purpose.
In fact, I wonder what percentage of commercial shops even have a lantern/rocker tool post, ha-ha-ha - ? But then, how many radii need to be turned on an engine lathe, it’s not exactly a routine operation, right ?
These are just meandering thoughts about a topic that may deserve more attention. Those with experience will know all of this but perhaps some information can be helpful to those learning the craft. As previously noted, one can take the position that hobbyists do not need to be concerned about the efficiency (time savings) of turning operations. That is certainly true so this can be treated as light entertainment :o)
However, here's something worth thinking about: what's not to like about having a lantern, rocker and a few Armstrong holders (especially the bent ones, both right and left) for that rare occasion when they solve the unsolvable problem ? It's not like this stuff is expensive, probably way less than the typical Chinese-made QCTP and sme holders.
These thoughts are not particularly comprehensive or even orderly – just things that have occurred to me when I started writing about improving my four way tool post.
It would be interesting if others added their own ideas/experiences. For example, I read somewhere, sometime, that a long boring tool might be partly supported by a machinist’s jack. I actually used the idea once and benefited from it !
RE: Thoughts About Small Lathe Tool Holders, Part 1 - f350ca - 08-19-2017
Some food for thought Randy. I've never had a rocker tool post for a lathe but have used the Armstrong tool holders on my Logan shaper. The built in angle saved grinding top rake in the tool, though not always necessary on the shaper. I haven't found any Armstrong tool holders for the larger shaper I have now, forget what number Im even looking for.
A while back I was thinking about making a tool holder for my home made quick change tool post that presents the cutter at an angle as did the Armstrong holder. Would simply be a matter of cutting the tool slot at an angle.
![[Image: X2zmDmoQxBRERSZlpP2iJ0n86_iB53BYTyV8h3YP...2-h1276-no]](https://lh3.googleusercontent.com/X2zmDmoQxBRERSZlpP2iJ0n86_iB53BYTyV8h3YPT-ypZbmQHIiiXW8WG9aoJtKw5yij08T07beJ_A5FVX7IzLf6RkPciU2qddwUmcOlZTozSVfpAGialEJQv_62sc3RbOJwVWEwkF4DBMIzkVII7uKrlXz2-HkEWLdZ8liC0eRxoA-xz-s0xhMGvPk5cNOnHuiHJks9Yj9xXmf-Gu-6XaIBio6wzX5pWtaLLrYdhkOV2bg7sHtGXkQWXusAMEsYiMu9rP0QgSNUgLPFAjq8bGWJO2DJJTiapwFidBOHtRz2O_fGMZDrilY7pIaXEy9PqnHNM0RRPeGG9cDivvG6nkX44JWIRtOcBK0rEDEFPi42cfhSOKhRKKwvdEgFjqCbSPCuLZnMxLZPsmY-JUVBxtEeowhMW3dK2v6wlt_gjJtqWcJivKfMUlGLm5cxOOzPoKIBAiVtJ_qaezmyWmFaxhyPvwQzLaA35uBfVVvy9_874-XLgCEecxx-ZZ_hV5JDlfhouW5WzlGXN3i0tIzGgL6-J_ubTPM_RBTFCJcGgyN6sQ6N9XH8olO1WRhapFzGeTlRzqskgfg00zdTRm3UdW17dAHDAEoYZ1lIQd5IXWUAFodLOGzR=w1702-h1276-no)
Making a tool post for the Summit to hold boring bars has been on the list for some time. I've made 2 inch dia boring bars for it BUT lost rigidity by cutting a flat in the end to grab with a tool holder for the quick change tool post. It was stiffer than my 1 inch indexible bar though. I used it here to bore the cylinders on a Wisconsin engine but built it originally to bore out bearing blocks on the tracks of an excavator after I built them up with weld.
![[Image: 9yF825Dhlcds9PtydLzgn1X4C9MoCVj-injn0v5J...2-h1276-no]](https://lh3.googleusercontent.com/9yF825Dhlcds9PtydLzgn1X4C9MoCVj-injn0v5JD5UMbVjkfFnts4uQaPQ8itk4hE_1_T9eJfT9I9Rt-RBfQcwa12dsK55Qp2bvA05bNoHCEMYYmdR6KkFtAneIiYsjlwnukybwsnmLB0wL8PN_N3R7oAxw43vPpcD2TosxV9IIjPDut-uIqBt9p9971hSqMnRD4Jbw5_EuGVD-DofTcL04R60dUclb_2hPxDbdE5KX18D0acAUcXHRkZyBXfxB1UdULkh3S-qYUCIhIHtkAhcRPJsg_tDg1tS6Ic4Wa42ttrokeFY48WUSbEqrIV6Dy72YieNfI08FwBiF8w4cTgDgLvQRoJmkqkb7Q3CIsO7YXyIntqmtzR5pChROyrQbcwAKaYOo1B0oS_YoV17fh677DPFV4xx7OzLbZe7FHBowvJfUWRdNWyCqyTwp-6F9otaYsjqKdyAoqKiOF07m5QuG9xWtkm04Pxdj0mF6OpdKX3P8Bc3wliB-mOKO8sl7sO_6ksy-4PP7FEyJqg0Ncwd9NyBdIeb43ar4lg8PFjvLSjt43XCaqEakZiSQESfeDKWY4UM8eSnlitHyTWKbyn_xY6zBNcckex_o4XpjlTKilbOAOY7g=w1702-h1276-no)
RE: Thoughts About Small Lathe Tool Holders, Part 1 - randyc - 08-19-2017
<<<<speechless>>>>
<<<<<almost>>>>>
Greg:
You are a Michelangelo of metalworking (AND woodworking) ! That is beautiful tooling - well conceived, designed and executed. It's a statement of how the concept of "form following function" can result in eye-catching work like yours. I really like that cool tool height gage but it's all great !
Being a complete hack, I could never summon the patience (and skill) to create tooling like that. BTW, are the holders bead-blasted or maybe acid etched, the finish is very attractive ? (I usually just torch my parts and drop them into a can of used motor oil, ha-ha-ha.)
Is that a HVL-H ?
P.S. I'm curious - why use the QCTP to hold your two inch boring bar instead of making a sturdier holder for it ?
RE: Thoughts About Small Lathe Tool Holders, Part 1 - Dr Stan - 08-19-2017
The Emco-Maier lathes are probably the best in their size and I was disappointed when they ceased manufacturing their manual machines. I was fortunate enough to visit their factory before that happened.
Their line of CNC lathes, especially the small trainer are matched by no one. Just by switching out the membrane over the controller you can learn different brands of controls.
RE: Thoughts About Small Lathe Tool Holders, Part 1 - the penguin - 08-20-2017
Randy,
interesting post, I have a set of the Armstrong tools, in a factory metal box, but I don't have a lantern post to use them.....
RE: Thoughts About Small Lathe Tool Holders, Part 1 - f350ca - 08-20-2017
I've been called a lot of things but never that Randy, Thanks lol I certainly wouldn't call your work hack.
No special finish, the body was a cut off from a shaft, didn't know where it came from, but it was really hard. Harder than heat treated 4140, no sign of wear after years of use. The form was what was left after I cut the dovetails. Don't know what I was thinking or not thinking, I didn't make the dovetails to match commercial ones. So My tool holders are proprietary. In defence I'd never used a QCTP before this one.
The height gauge works on the saddle or the top of the compound.
The boring bar was put together quick while I was having problems machining the welds I'd done to build up bearing blocks. Someone let the shafts on the idler and drive end of an excavator track wear through the bronze bushings and into the casting. This was quick and helped a lot. Making a proper mount is on the ever growing list.
The lathe is an HLV, drop the H. Picked it up on a government auction. Needed some work but had very little wear. Its a year younger than me. Here's as link to the repairs.
http://www.metalworkingfun.com/showthread.php?tid=1010&highlight=hardinge
RE: Thoughts About Small Lathe Tool Holders, Part 1 - the penguin - 08-20-2017
Greg,
awesome work
RE: Thoughts About Small Lathe Tool Holders, Part 1 - Highpower - 08-20-2017
It always is as far as I can tell.
RE: Thoughts About Small Lathe Tool Holders, Part 1 - randyc - 08-20-2017
(08-20-2017, 08:49 AM)f350ca Wrote: .....The lathe is an HLV, drop the H. Picked it up on a government auction. Needed some work but had very little wear. Its a year younger than me. Here's as link to the repairs.
http://www.metalworkingfun.com/showthread.php?tid=1010&highlight=hardinge
Greg,
God, I wish I hadn't read that thread. I'll forever feel that my 1945 Sheldon is a POS. Why, oh why, did I not wait until a $1200 10EE or $1200 HLV-H came on the market, ha-ha-ha
Insofar as making your tool post compatible with Aloris dovetails, IMO parking eBay tool holders on that Hardinge would be near-sacrilege when compared with your own tooling system !
Hey Jack,
I see lanterns/rockers on eBay all the time, from $20 to $50, the smaller ones anyway. You might give the Armstrongs a try on a special job where a QCTP is sort of awkward.
Cheers !