Size of a tool (lathe!)

Ed described their versatility very well. I made this one from a bolt to be able to use the lathe:

fender washers trimmed to fit into the tee slot on the compound. The chain-drilled slot was very rough at first but that didn't matter, only the spherical washer and the bar that rests on it need to be well finished. I fitted the bar by smearing blueing on the washer and repeatedly filing off the contact marks, mostly with a coarse rasp that left the crosswise lines. The clamp bolt should be hardened or it will mushroom on the end, as you can see. I will need to grind that one down with a Dremel to get it out.

Instead of the spherical washer and rocker bar you could use a stack of large washers or a section of water pipe. A threaded joint cut from pipe and a fitting would be adjustable for height. As Ed said they have no real advantage in use, but they are easy to make from common hardware with simple equipment. That one was turned between centers and drilled a little crookedly on a drill press.

I still use it occasionally when I need a less bulky tool post, for instance to turn a ball by swiveling the compound.

This is the tool post I like best, the Multifix, which is quick and solid like an Aloris but rotates almost like a rocker post. Chinese clone tool holders from Tools4cheap fit the Swiss center column perfectly.

Phase II.

Jim Wilkins

They are a very old design. They originally held high carbon steel tools which were shaped in a forge to provide the needed tip orientation, and then hardened by quenching and (likely) tempering.

Later, there were forged steel holders for the standard square HSS lathe bits. Armstrong was the originator (I think). They were available with the bit pointed straight ahead, bent to the left (for working on the right-hand end of the workpiece), and bent to the right (for working on the left-hand end of the workpiece.

The HSS bits were put into square holes broached through the forging. The holes were tilted to produce rake, so you did not have to weaken the HSS toolbit by grinding rake on the tip, since the HSS bits were a lot smaller than the original tools.

Later, when brazed carbide tools came into use, there was another series with the broached hole horizontal instead of providing rake.

But the original thing which make the Lantern style toolpost and the holders quite popular was the ease of making the toolpost, and the ability to raise or lower the tip by tilting the rocker.

But they did lack rigidity -- one of the things which made turret toolposts, and later quick-change toolposts popular.

At the bottom of the toolpst is a segment of a disk of steel (similar to a Woodruff key) which rests on a ring with a section of a negative sphere turned into it. This allows tilting the tip up and down, adjusting the height (but with the disadvantage of also changing the rake angle).

Metal shapers use a lantern style toolpost -- but with a totally level ring around it -- no tilting, because that is handled by the clapper box on which the post is mounted.

Nope -- the HSS bits in Armstrong style toolholders in a lantern style toolpost are tilted to produce a rake without having to grind one into the bit. The quick change toolpost is normally used with carbide insert tools, so the carbide can be used with zero rake from the post and the holders for the inserts introduce either zero rake or negative rake, depending on the insert in use. Brazed inserts all have zero rake as far as I know.

Yes it does -- significantly.

Just not as much of a disadvantage on a floppy machine, because the machine is already contributing enough flop for everyone. :-)

Enjoy, DoN.

I've used an O.K. Rubber Welders square indexing tool post for years. I prefer the design over the quick change holders, but only for small work. If you mount a boring bar with a short shank, and the work is small, you can still mount four tools. I've even crowded five tools in a setup, although the fifth tool was mounted at a strange angle, held only with one screw, and was used strictly for chamfering. The OK tool block offers positive indexing @ 3 degree increments.

Harold

Fact is, it has little to do with comfort. A rocker tool post does not allow for production machining. They are totally worthless for that purpose, which is why they are not found in industry. They are flexible in that you can achieve pretty much any angle of approach to the job, but you can't mark dials and make time with them. I would avoid a rock toolpost at almost any cost, assuming I had intentions of making more than one of anything.

Harold

I thought I could achieve pretty similar result by shimming the workpiece so it sits higher up in the jaws. I tried it with the chuck on the table and it seemed to look OK. Of course looking is one thing and turning is another...

Even grinding I do not rely on the magnets alone. That is where the central boss comes in. It stops the lateral movement of the piece. The magnets (4 of them) stop the vertical movement. I was hoping that the combination might work for facing if the boss is sufficiantly tight inside the doughnut hole.

>

Looking in Advanced Machine Work that seemed to be the only toolpost then. In fact they do not discuss toolposts much at all.

OK. In the picture the rocker bar is "upside down". Now I see why they called it a rocker toolpost. In a lot of the literature and web references this feature is by no means obvious.

Looking at it I wonder if the slot was milled in the threaded part of the bolt could one not use a nut or two to adjust the height of the tool? Aslo, how is the toolpost held on the crosslide? I take it there is a capscrew that goes through the hole in the bottom and screws into a tee-nut which then goes into a tee-slot? Or does the whole thing screw down directly into a taped hole in the crosslide (or compound)? Given the nature of the rocker bar and its position the capscrew length must be fairly critical so that it is long enough and not too long to interfere with the bar.

In all honesty I think I am jumping ahead of myself. I think the first toolpost will be something very simple

(page 6)

just to establish that the concept actually works. However, I now know more than I did before and when (if) it comes to making a permanent toolpost the choice will be easier

Well, if you're doing production turning in industry, a recreational crafts newsgroup may not be the best place to ask about toolposts. d8-)

I'll remember that the next time I do a production run in my basement.

-- Ed Huntress

Check the back issues of the "Home Shop Machinist" or "Machinist's Workshop" for exactly this project. IIRC this was called a Swiss type holder.

You might want to take a look at the KRF "omnipost" plans/kits. You can make these with only a lathe [with milling attachment] and a hacksaw. I made these and they work fine. You may want to buy the notched index plate that goes under the tool post as this can be difficult to make, but these are not expensive.

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).

If this looks interesting, I came across this website showing step by step procedure during another search.

FWIW -- The first few holders I made were before I bought the KRF plans. [I don't know if KDF still sells these] These worked well enough, but the screw sizes are such that I need two sets of hex keys to adjust. With the plans and the specified hex screws, you only need the single set.

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).

Don't redesign it before you understand it. The flange on the lower end fits into the tee slot on the compound. The top screw clamps the washer, rocker and tool bit/holder solidly down onto the top of the compound, meaning that you have to readjust it all if you loosen that screw. You use the tailstock center point or an experienced eyeball estimate against a chuck jaw or the work to set the cutting edge height. Hopefully you won't use one long enough to become an expert.

The strap+bolts is how I turned the rocker post. I would have 4 tapped holes in a square so the bit could be set closer to parallel with the ways, to bore the center hole for instance, and to put a second strap further back for improved leverage.

Carriage bolts are easier than hex heads to modify into tee slot studs . File a washer to almost fit the square and pound it on, trim it to the slot width and grind the head thinner if necessary.

A disadvantage of that design is the fixed height of the tool bit which as shown doesn't allow Armstrong-style holders. If you find some, and you should look, you will need shims to set the bit on center. A stack of small thin shims is a royal pain since you have only one hand to hold them in place while tightening the clamp screws with the other.

With the turret or KRF styles you don't have to shim and clamp the bit as often, only when you change or regrind it.

The rocker post avoids small shims by tilting the holder, which also changes the effective front and top rake of the cutting edge. It will hold naked tool bits if you block them up with bar stock or other tool bits. Neither type is ideal but either will get you started.

Jim Wilkins

It is tricky doing this. You need a set of parallels of the right size to support it -- or an aluminum extrusion "spider" which fits between the chuck jaws and holds itself in place with magnets gripping the chuck body face.

The spiders are neat -- but are rather expensive for what they are.

The parallels must be removed before you spin up the chuck -- or they are likely to hit you somewhere.

The advantage of turning soft jaws for the purpose is that you will have support over most of the radius of the workpiece. Your workpieces are fairly thin and would be likely to ring. Hmm ... if you make the soft jaws from aluminum, you can embed permanent magnets in the end away from the gripping step. (You will have problems with the chips from steel piling up on the magnets, however. For brass or aluminum, no problem. But good strong magnets in the jaws will help to control ringing, and since you are going to be doing this a lot, it is worth while making proper tooling for the task.

Of course -- there are also pie wedge soft jaws, which form an nearly complete circle when the chuck jaws are at the tightest setting, and those can be turned for your workpieces. You can even turn several diameters working as steps from shallow at the OD to deep at the ID, so progressively smaller discs can be gripped.

Your "doughnuts" are actually disks not things thick enough to be proportional for a doughnut, aren't they? Say an 8" disk perhaps 1/4" thick or so?

I'll bet that you will find that the magnets are not strong enough for turning -- the workpiece will spin around the boss.

Good Luck, DoN.

[ ... ]

Because there was only one common choice back then. It was when production lathes like turret lathes came along where the ability to quickly change the tools and have them repeatably positioned became important. First, indexed turret toolposts, later quick change toolposts of various sorts.

:-)

I've got some small ones designed for Unimat lathes which have a two-part ring without the rocker feature. You adjust it for the needed height by turning the top part which is threaded into the bottom part. The bottom ring has a raised part which engages the T-slot so it will not turn while you turn the top part.

Looking at the image in the URL left quoted above, look at the bottom of the toolpost. It is turned to a diameter and thickness so it fits into the T-slot cleanly. The ring and rocker press on the top of the compound when the tool holder is clamped in place by the screw at the top. The traditional ones had a square head screw with a flange so standard wrenches which also fit other clamp screws and such could rest on the top of the screw for easy access when you need to change something. Once you clamp down with the screw, everything is firmly held in place.

I've seen some with a two-part base -- the round one shown there, and a rectangular one with a counterbore to accept the round base of the normal toolpost. This is done mostly (I think) to adapt a smaller toolpost to a larger lathe compound.

Similar to (but cruder than) the one for the Unimat which I have.

And the "between centers" explains the apparent hole in the center of the bottom -- it was for making the post, not for a screw to secure the post in place.

[ ... ]

That is a steal! How many tool holders came with it for that price?

O.K. The whole design of the lathe shown there is rather crude, but should work for light cutting at least.

Good Luck, DoN.

I checked my back issues and the article you want is

St. Louis, C. (2007 August/September). "New Light for your Lantern Tool Post." Machinist's Workshop, 20.4, 6-15.

The article shows the standard rocker style tool holder and how that works as well as showing an improved height adjustable feature, which can incorporate the existing ring/rocker if desired, but not required.

Note that there is no modification to the tool post or lathe if this is a consideration.

The "Swiss" reference I recalled was to a Schablin manual toolroom lathe.

Some cautions:

As is common in many hobby projects, the machining appears to be more elaborate than necessary, and some avoidable problems are created by buying material close to the finished sizes, leaving no room for "service flanges" used to hold the work while machining, but which are turned off, or the part parted off as the last operation.

Three specific examples:

(1) The milled anti-rotation flats on the adjuster screw/sleeve that fits over the tool post are not required. A much simpler anti rotation solution is to drill and tap holes in the proper location and install small [#8/#10] SHCSs. This eliminates the need for a milling machine or lathe milling attaintment for this part, although precision layout and careful drilling, possibly on the lathe faceplate will be required for a close fit in the compound [top] slide T slot. Get sufficient length of material [1_3/4 OD + tool post ID + c. 0.010/0.020 [or solid] X 4 to 5 inches] to clamp in the three jaw, and part off the completed part. This is an external 1_3/4 X 20 thread. For our international participants I am sure that a 1.25 or 1 MM thread will work as well. If you face the part, drill and bore the part, externally thread the part, and then part off the part [c. 5/8 but your lathe may require different thickness], this will insure that the faces are parallel and the thread is perpendicular to the faces.

(2) While the vertical fluting on the adjusting nut is very elegant looking, and I am sure works well, it requires a milling machine and dividing head. A good coarse knurl will provide the same function, and no finish at all may well be adequate. At the very least a knurl eliminates the need for a milling machine and dividing head, and it may well be possible to skip this step entirely.

(3) If a longer piece [4-5 inches] of heavy tubing or even a solid bar is purchased for the adjusting nut [2.75 OD X 1.70 ID], it can be clamped in the three jaw chuck. This will have an external knurl [or possibly nothing] with an internal 1_3/4 X 20 thread. I strongly recommend that you bore/drill the hole through or at much deeper than required, and cut a recess/relief for the tool to feed into. While it is possible to thread to the bottom of a blind hole [after many years of practice] it is much easier with through hole. If you face the part, drill bore, and thread the part, and then part off the part [5/8 thick], this will insure that the faces are parallel and the threads perpendicular to the faces.

Good luck with your project, and let the group know what you discover and 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).

Also, different parallels for different thickness pieces. The current method of holding looks better all the time :-)

You are right. That might damage them!

That is right. The most common ones are 4.5" OD with a 2.1" ID and about

0.19" thickness (that varies quite a bit). But I have some with 5.5"/3.2"/0.25" on deck and some even bigger. So far none larger than 7.5" OD. Although my biggest piece was 12" OD it is unlikely I shall be doing something that size in the near future for various reasons.

Here is where I was thinking the other way: Face as close to the centre as possible. Then bore out the "dirty" bit...

No takers!

I got the hacksaw...But thanks for the detailed information here and in your next two posts. I shall keep them for future reference. They will be very useful.

OK. I think Don explains the hole in the bottom further on. The "between the centres" bit...

I got good at that when I discovered that my new drill press t-slots did not take the common t-nuts. Why do the Chinese like 7/16" so much?

Thanks.

I think I am about to re-define "crude"...

------ Because this is not 7/16. It is a standard metric size T-slot that 7/16 happens to fit.

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).

Pie jaws:

have to be quite close to the size of the work. It's nice for lens rings etc but not for general work. The internal mechanism is slanted bar cams as shown in an early Holtzapffel drawing.

Your 3-jaw shims can be rings cut from plywood or discarded plates with a scroll saw.

I make pulley and other wheels on a plywood-covered faceplate. First I drill a small center hole for a locating & centering pin. Then I attach the blank to the plywood with screws in the waste areas and turn the friction-reducing recess between the rim and the hub on both sides, using the pin to recenter the blank. This is equivalent to you facing both sides, BEFORE turning the OD and ID.

If you want a bevel around the inner hole you could cut a shallow recess where the hole will be and bevel its edge, leaving the center to support the disk.

Next space the disk out from the plywood with collars on the screws, in your case probably the inner ones, and turn the OD.

Add a ring of screws and collars around the OD, with washers under the heads to spread the grip and protect the finish. Cut the center loose by wiggling the bit sideways slightly for clearance as you run it toward the headstock. This should work on the OD as well, with the benefit that the outer screws support the blank better. The bit I use for this plunge cut is rounded on the end with parallel sides, both relieved to cut. I use it for the cable groove too.

Or reverse it, bore the center first and clamp the disk to the plywood with a plate larger than the hole and again the spacers on the screws to support the disk. This way will be harder to assemble but safer.

The best way might be to attach a temporary wooden block to the center and turn it to fit the bored ID snugly, then screw another clamping plate over it to sandwich the disk. Then the disk could slip without causing a problem when you turn the OD. The lathe's tailstock does a fair job of clamping the outer plate.

Use brass or soft steel screws, NOT sheetrock screws which are hardened.

You could make clamps out of small short bars drilled through the center for the clamp screw and tapped through the outer end for a stand-off screw to make them sit flat on the disk. Be careful, they grab clothing.

The spacer collars are easier to mill than turn to identical length. They don't have to be cylindrical, cross-drilled bar stock is fine.

My lathe will take collets and a faceplate simultaneously, so I center the blank with the locating pin in a collet and then attach it to the faceplate. Unscrewing the faceplate pops out the collet adapter.

Hals und beinbruch,

Jim Wilkins