Question On Double Cross Slide Tool Holder And Compound Rest Base

Shiseiji

Shiseiji

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Are the compound rest bases on Logan/Wards, Atlas/Craftsman, SB the same sizes? I've been looking at tool holders and pages of forum postings and darned if I can figure it out. And if not, what do I need to check for when looking to purchase one or finish one from Metal Lathe!?

TIA

Ron
 
Not quite sure what you're asking. Are you looking for a QCTP?
 
To answer your first question, generally yes, at least up to 12". However, the T-slots are all slightly different. And there is some variation in the vertical distance between the flat top of the compound slide and the lathe center line. If you are looking at making a QCTP for an Atlas built 12", make it the same size as the AXA or 100 Series. The BXA can be made to work but in general people who bought a BXA fall into two groups - those who admit that they made a mistake and those who don't. And you will probably get more comments over in the Atlas forum, but I'm not going to move the thread.
 
Clive,

I read through the thread and asked him whether he wanted me to move it.
 
Cleve, you are spot on. Sorry, I do have a Logan 821, S/N 48113, ~ 1948 so I thought I should start here. I've read a lot about the pros and cons of doing milling on a lathe. I still want to try it. I don't have access to a mill, so can't use a rough casting from Andy @ State College Central. I've been offered a cross slide like eBay item 261934867376 http://www.ebay.com/itm/261934867376 @ "less than eBay prices, $125 + S&H. I don't know anything about what can move between a Logan and anything else, so have to ask.

Sorry for the poor starting explanation.

Ron
 
There are two ways to do milling on a lathe. The Globe unit is one, and actually the only example of that approach that I have ever seen. The gadget moves the secondary spindle containing the milling cutter in the vertical direction. To complete the setup you need something like a boring table (usually a cross slide with T-slots for clamping parts) mounted on the carriage in place of the standard cross slide that holds the compound. And you get movement in the other two directions out of the carriage and the cross slide.

The other method uses a different gadget commonly called a "milling attachment" which usually mounts in place of the compound. The spindle holding the cutter remains in one fixed location and the milling attachment furnishes the vertical movement. There is usually a small vise on the milling attachment to hold the work pieces, which are generally pretty small. The Atlas version can also be used with the rotary table off of the Universal Compound Vise (nominally a Drill Press accessory). With this setup, I have successfully milled slots in BC-611 cases, which are about 3"x3"x12".

Myford offered a similar attachment, which may be a little stiffer than the Atlas one. I don't recall whether I have seem similar attachments from Logan or South Bend, but they probably made them.
 
[I'll be able to get back into the shop this week. Once I do, I'll start a new thread in this forum to post my progress on machining the replacement cross-slide using Andy's casting.]

Regarding the original question, I think most small (9", 10", 11") benchtop lathes had compound slides that were roughly the same size between South Bend, Logan, and Atlas (though the slot sizes were different as mentioned previously). Each vendor attaches the compounds to the cross-slide in very different ways. I believe SB uses a "circular dovetail" clamping mechanism of some sort, while Logan uses clamping bolts in a circular tee-slot. The dovetail design is probably slightly superior, but I've had no problems whatsoever with my Logan compound. Andy's casting certainly fits my lathe just fine (the gross dimensions are shown at that link).

Andy does make a different casting expressly for an Atlas lathe, but it's solely intended as a separate "boring table" rather than as a complete replacement of your existing cross-slide (that is, you aren't expected to mount your compound to it).

Regarding milling on a Logan: I've got a Palmgren milling attachment and before I acquired my mill I successfully milled a few simple parts, but man was it a pain. Amongst other problems, attaching the Palmgren to the compound (rather than in place of the compound) just doesn't provide sufficient rigidity. The heavy vise/milling-attachment is just too top heavy that way. Tramming is a real headache, and my Palmgren just has a knurled knob for traversing in Y (up and down) — believe me, turning that knob gets old quick. I think some units have ball-handles for cranking in Y, which would be very welcome (if I end up using it again for anything, I'll likely replace the knurled knob with something better, but the vise handle limits the available space for a ball-crank).

Basically, the stock Logan cross-slide (on my 1941 Monkey Wards 11" Powr-Kraft lathe) just doesn't provide a good attachment point for the Palmgren milling attachment — you're forced to attach it to the compound itself.

I've no direct experience yet, but I'm convinced that a "boring table" (or longer, and squarer, replacement cross-slide) will provide a much more rigid attachment point for tooling and parts during milling/facing/boring operations. It's the difference between bolted-on legs and welded legs on a table — its surprising how much rigidity you lose with each bolted-together connection.

Even though I eventually threw in the towel and purchased a mill ("honest, honey, I need just this one more machine") I suspect that some milling-style operations are still better suited to the lathe. Sometimes you just want to spin the part rather than the tool. As a hobbyist, I also really enjoy old-school ways of doing things (like using faceplates, turning between centers, using toolmaker's buttons to setup for precision boring, etc.). Such operations are far easier to accomplish with a "boring table" style cross-slide vs. the stock short slide which has few square surfaces.

For my summer projects, I purchased Andy's castings for the boring-table/cross-slide, rear-mount toolpost, and a "transfer block." I'm making good progress on the boring table, but haven't started the latter projects. I'm happy as the proverbial that these projects are exposing me to all sorts of new techniques (slot milling, scraping, etc.) and, even better, forcing me to build or purchase more tools! <laugh> I'm also pretty sure that once complete, I'll be able to do even more with my lathe than I could with only the stock cross-slide.

The beginning of the entire adventure for me was acquiring George H. Thomas's "The Model Engineers Workshop Manual." As I started making a few tools from that book (the scriber, rule holder, and finger plate so far) I started lusting after a "boring table" type cross-slide to allow me to use some of the other projects from that book. It appears that Andy's castings are based on Mr. Thomas's designs (or at least are quite similar).

Regards,
--
Rex
 
Rex, thanks. Like so many things, it's learning enough vocabulary to be able to communicate. I guess what I was envisioning was mounting the Tee Table on the cross slide (carriage in the Logan manual?) , then using something like Andy's boring and milling transfer block shimmed as necessary for height to mill slots at a right angle. About as KISS as I could see. Hence the original question on mounting the Tee Table to the cross slide. Ignorance on how it is all built up . . . I knew the attaching methods were different, and I suspected far more then that was different too. But . . . couldn't find anything so I asked.

R
 
Yup. Communicating accurately in written text is hard (which is why photos, drawings, and video are so valuable on this site).

Wikipedia has a pretty good article that names the various parts of a metal lathe (follow the link in that sentence).

Here's the relevant diagram from that article:
1280px-HwacheonCentreLathe-carriage-mask_legend.jpg

I think the relevant words you are searching for are "saddle," "cross-slide," "compound slide," and "boring table". Confusingly, some people also call the compound slide a "top slide" (usually the same people that add an extra syllable to "aluminum" ;-).

The saddle is part 4, and includes the dovetail way for guiding the cross slide — the (male) dovetail is visible on the far side of 3b and underneath the cross slide (part 3).

The cross slide is part 3 in the diagram and the compound slide (or top slide) is 2.

What you are calling the "tee table" is, I think, usually called a "boring table" which I understand is itself a form of cross slide. They slide fore and aft across the ways of the lathe, usually guided by a dovetail on the saddle (part 4) as shown. It wouldn't make sense to mount a boring table ("tee table") to the cross slide — you use it as a cross slide itself (with things like boring bars or parts mounted to it).

Some lathes (like mine) only have a short cross slide that is only used to mount the compound slide and toolholder. They don't have a table like 3a that extends all the way to the back of the lathe like the one shown.

Andy Lofquist at Metal Lathe Accessories makes both a pure "boring table" casting for Atlas lathes, as well as a "hybrid" replacement cross slide with a long table that holds the compound as well as providing tee-slot mounting locations at the rear. The former requires you to use the original short cross slide when using your compound, and the latter acts as a complete replacement for your cross-slide (making the original redundant).

The castings require you to mill the correct sizes of the dovetail, etc., specific to your lathe. So to answer your original question at the top of this thread, you need to verify that the basic dimensions shown for the casting you want fit your specific lathe (the castings are, of course, larger in coarse dimensions — you need to mill them down to the appropriate size). Here is a nice explanation of one person's experience in fitting the S-4382 to her South Bend lathe. I'll be posting a similar thread to this forum regarding my experiences milling it to size for my Logan.

Hope this helps.
--
Rex
 
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