Tool post build

[BCRider]

Ah, tool posts.... one of my favorite topics. And one sure to get a lot of responses from folks around this part of the interwebz...

Before I finally bit the bullet and ordered up an AXA clone and bunch of holders I was very close to doing own thing based on the sketches shown.

I'm not a fan of the actual four way posts because after some years of using but not really liking them I find that the tools often foul the adjacent positions rending them at best a three way post and often as not limiting them to a two way post instead. Plus as tools come and go there's the need for stacks of shims to deal with each tool so the cutting edge is dead on the center height.

So my thoughts for keeping it simple but at the same time make for easier switching between tools was to make up multiple two position tool blocks that could be made fairly easily. This started out with the boring bar and knurling tool blocks shown in pictures below. And it even got to making up one block to try out an option for a multi angled cutter which could be sharpened from the ends right to where there would be just a little nubbin left. That's also shown below.

As well as the basic tool holders I'd planned on making a block with one side that held parting blades correctly. Just need to play with some options for figuring out how to make the slightly angled cuts to allow for tapered parting tool blades.... If you like this idea we can discuss it and work it out together. Of course if you have a milling machine then it makes it pretty simple.

In use the blocks are easily and rapidly swapped by simply spinning off the cap nut, switch blocks and spin the cap nut back down. The extended cap nut is both to make it easy to thread on rapidly and also to lift the box end wrench up away from the clamping set screws. I prefer a cut down box end wrench for the tool post because I can position it in any of twelve angles as I alter the angle of the compound and thus where the wrench would be if it was a dedicated fixed rod. But of course we now need some way to make the hex. But if you're patient it can be done using a file. Or perhaps a good size nut could be welded to some stock then turn the rest to finish size.

In the end I decided to just get on with other things and about two years ago bought one of the imported AXA clones just because the cost had come down or I had just gotten impatient. And I do like it. But I think that a few of these tool holder blocks could have been a fairly decent option. And best of all you could make them directly in the lathe if you don't have a milling machine.

[Bented]

This is a new low dollar lathe that I have been running since this past March, it sports a 4 position horizontal tool turret, it is simply a 4-way that indexes automatically. There are many ways to crash a long tool into something, I have hit the door and the tail stock so far, the indexing mechanism has little power on its own so no harm has been done.
If OD turning when using the tail stock the black sheet metal box that houses the indexing components will quite easily crash into it.

Beats the hell out of a QCTP when running several hundred parts with 4 tool changes per part.

I have however spent a good deal of time shimming tools to height in this machine. Spindle center is 1" from the bottom, most insert tooling for OD work holds the insert at the height of the square shank, so 1" square shank tools do not require shims, internal tools are a different animal.

[J Tiers]

After looking at it closer there is no one size fits all is there? Thanks

There can be a one size fits most. I have one, and would be happy to post dimensions if you like. it takes 4 sizes of tool, and holds them all with the top at the same level. That works for me, as I have insert, brazed, and HSS tools, and like to have the edge at the top.

If interested I will measure and post.

[Doozer]

I thought he had a Smithy lathe and mill combo.

--D

[Paul Alciatore]

OK, attempting to provide some concrete answers. Well, hard rubber ones at least.

First, here is a link to an internet search for "four way lathe tool post plans build".

https://www.google.com/search?sxsrf=...ih=569&dpr=1.5

Wow, that is a long link, probably due to the multiple search words. Anyway, they have a bunch of photos and some of them are for drawings. But, as you probably already suspect, these things must be sized to YOUR lathe.

I have not built a four way tool post. Instead I opted to design and build my own Quick Change tool post which was a tremendous success. I will provide a link at the end of this post. But many of the design considerations will be the same.

My first observation is that the four way tool posts come in a number of variations and many of these variations are of a ONE piece version which does not have any base or ability to index it. They are simply a block of metal (cast iron or steel) with channels milled in the sides for the lathe tools.

If you are going to make that simple version the design math is rather simple. From your 1.5" center height of your lathe you subtract the size of the tool bits you wish to use and that number is the dimension from the bottom of the post to the bottom of the groove. You probably should subtract a bit more to allow for differences in different brands or lots of the bits; perhaps an additional 0.010" or more.

To that number you add the height of your tool bits and then about 1/16" for the slot to make installing the tool bits easy. Then add another 1/2" for the screws that will hold the bits in the groove and you have the height of the tool post.

The only other dimension is the size of the square as viewed from above. This is also the width of a face. You did not say what size your lathe is so I must assume it is around 8 to 10 inch swing. For that I would suggest a face width in the range of 2.5 to 3 inches.

The rest is just a matter of screw and hole sizes. The center hole is sized to the stud you will use and that depends on the width of the Tee slot in your compound or cross slide where the post will mount. I would guess 3/8", but you should measure any existing stud or screw you use for the present tool holder(s).

Next there are variations of the four way that do have indexing. These work in a number of ways so it is hard to generalize on the base design. One thing I can say is that the base height needs to be subtracted from the bottom of the tool post to the bottom of the tool bit slot number I mentioned above. And AFTER subtracting that base height, you need to have enough remaining of that dimension to provide a ledge that is strong enough to support the tool bits with all the cutting forces they will generate. Again a guess but I would recommend at least 1/2", certainly no less than 3/8".

I said I would provide a link to my QC tool post/holder. It provides a number of advantages over any of the four way designs. Like any QC tool post, it provides the ability to have tools return to the same position so if you are making multiple parts you can use several tools with the same dial settings. This can be an enormous time saver when making identical parts. It is also very solid; I believe more solid than most other QC tool posts. It features the fastest tool change of any QC holder, bar none and that change can be done with ONE HAND. As for making it, probably the most challenging part of making many QC tool posts is the dovetails which must be cut on both the posts and on the holders. My design does not use dovetails so the work needed is only standard turning in a lathe or milling using standard end mill cutters. It is a bit of a project, buy I believe it is possible even for beginners.

PS: Even though my post uses a round design, it also incorporates features that allow precise return of the tool to the same position after a tool change. Many round column, QC tool posts do not have this feature and others that do, implement it in a poor manner. My design is very robust in this regard and is even self compensating for the inevitable wear.

You can read more about it in these previous posts:

https://bbs.homeshopmachinist.net/fo...00#post1872000

Scroll down to post #5.

And

https://bbs.homeshopmachinist.net/fo...93#post1220993

Scroll down to post #6.

Here is a photo:



There are links to where the article describing it's construction in the above threads. The original article appeared in the Feb-Mar 2010 Machinist's Workshop which is still available on the Village Press website.

https://secure.villagepress.com/stor...ge/5/item/2048

The latest version is for sale at $10 here:

http://www.homemadetools.net/forum/q...st-lathe-52118

And you can download a free version (Rev. B) here:

https://www.dropbox.com/s/dxj9jv20ji...ostRc.doc?dl=0

PS: I just noticed that BCRider mentioned the shimming that is necessary when using a tool in any of the four way designs. I have had to deal with this on other machines and it can be a real PITA. Although it is not readily apparent in the photo, my post does incorporate a separate and independent adjustment for tool height in each tool holder. It is in the hole on the top of the holder between the post itself and the left most screw. It is easier to use as compared to that on the dovetail holders in that no locking nut is needed. Just adjust it and it holds that adjustment.

[Doozer]

Ok, keep it simple.
Start with what size tool bit do you want to use in your lathe?
Say 1/2" square for example.
The tip of your tool has to be on center.
Basic, but worth repeating if you are just starting out.
So if your top of your 1/2" bit is on center,
then how much distance between the tool and
the top of the compound where the tee slot is for bolting
down the tool post.
Maybe you have 1" of space to spare.
Then find or make a toolpost that accommodates your 1/2"
tool bit with 1" of space below it, down to the compound.
Lathes can be different swings and still have different
measurements for the height of their compound slides.
So begin with figuring this dimension and see what
you need. Look at the web sites of some big name
toolpost manufactures and read up on how to measure
your lathe and select the proper series toolpost.
It is NOT based on swing. Read between the lines.
Even if you make your own, you will still see what
to look for as far as dimensions.

-----Doozer

[BCRider]

If you're dead keen on a four way then I believe that most of the pictures out there will show a post that is pretty well the same size across the square as the compound rest is wide. Sort of like the one shown in Bented's picture.

As suggested they are not made from plates that are bolted together either. Although for a lighter duty machine I suppose that it could work. if you opt for that option then use lots of smaller screws rather than only four bigger ones so you more effectively "sew" the plates together with more points of full contact. For example a four inch square outside post might have a 3 inch square mid plate. For something of that sort I'd go with 1/4-28 NF screws set with mid or higher strength thread locker since this will be a permanent joining. And for the 3 inch square size I think I'd use at least 8 screws. Four in the corners and four at the mid points. Run then in from below so you don't have unsightly hex sockets to collect swarf.

Bented, that's a slick machine. I'm thinking pick your shims and actually bond them to the tool holders so they fit directly and the shims don't get lost? Or at least make up a little container so the tools and shims stay matched up?

[Randy]

Decades ago I built a 4-way tool post to replace the rocker style. I based it on a catalog photo of a Royal 4-way, which indexes at 30° increments. Repeatable tool postioning is a big benefit. (I made mine 15° increments.) It served me very well for a long time, shims notwithstanding. Eventually I replaced it with a shop-built QCTP, carrying over the indexing feature. Another huge step up. I wish it had done it much earlier, but the 4-way worked well enough that I wasn't strongly motivated. I considered purchasing a QCTP, but none of them have the indexing feature which I was unwilling to forego, and none but the very smallest would work. and I didn't like the smallest. (One of the quirks of my Jet 1024 is that it is only 3/4" from top of compound to spindle centerline.)

When you're upgrading from your rocker tool post I'd suggest you consider making the jump to a QCTP, whether you buy or make. If you step up to 4-way you'll need to make your own. With a QCTP you have the option of buying or making. The Chinese ones have become pretty affordable, and I gather they're resonably good. If you decide to make one you may not save much, but the satisfaction and enjoyment are reason enough to build. A lot of time, but this is our hobby, after all. There are lots of great ideas here and on YouTube, some of them plenty do-able.

As for the indexing feature that I'm so fond of, I think it's almost essential for a 4-way, not so much for a QCTP, at least if there are two dovetails at 90° like most commercial ones. I still like it, and made it practical to have a single dovetail, which I can swivel to the two most important orientations. The first QCTP I ever saw was a KDK, so a single dovetail was in my mind from the very start. If you choose to make a simple, single dovetail design, like several out there, at least make a way to index those two positions. Repeatablility as you change from turning to boring and back to turning is very desirable.

Lots of good advice here, and I agree with BCRider that a 4-way really gives you only two or three useful positions most of the time.

[welderskelter]

Wow. I have a lot to read here now.I have always been one to build what I can so will probably build it.
The center of chuck is 1 and a half inches higher than where the tool post will sit.

[Doozer]

...The center of chuck is 1 and a half inches higher than where the tool post will sit.

Who's your cherry popin' daddy ? Yeah !

-D

[mklotz]

30 sets of plans for lathe toolposts...

https://www.homemadetools.net/forum/...ol-posts-83181

[J Tiers]

The one 4-way to hold 1/4", 5/32", 3/8", and 1/2" no shims.

[Paul Alciatore]

No shims = not on center.

I have played that game and tool bits do vary in size, not to mention changes in the height of the tip after resharpening. I am sorry, but for best results in tool holders without their own adjustments, shims are a necessity.

The one 4-way to hold 1/4", 5/32", 3/8", and 1/2" no shims.

[J Tiers]

No shims = not on center.

I have played that game and tool bits do vary in size, not to mention changes in the height of the tip after resharpening. I am sorry, but for best results in tool holders without their own adjustments, shims are a necessity.

Sorry to burst your absolutism, but it works.

It's a really odd thing but the toolpost does not realize that it actually does not work.....so it just keeps working as always. And it really does not care about your opinion, when you have not ever used it.

Have never used a shim with it, and for some reason it puts things on center no matter what any armchair critics think.

[BCRider]

You must not be taking any material off the top of the blanks then. Or are you using it with insert holders that happen to put the insert at the nominal shank height? For form tools, and I do have a bunch for all sorts of things, the carefully made block as you show would work. But all bets are off as soon as I start grinding on the top side.

I'd also think that I'd want to do the 4 way posts with only one size per post so I could set the tools into the corners from either adjacent side. So while I like the idea of the blocks intended for each size of tool blanks I would not want to mix them on one block since at some point they would get into each other's way.

It's this constant getting in the way between tool directions that made me finally adopt the idea of the two slot narrow bars in my sketch. And having both "right hand" and "left hand" versions to deal with all the options.