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Adapting A Machine Dovetail?

mephits

Iron
Registered Member
#1
I have a question for the more experienced folk out there.

I have an Atlas 3981/Craftsman 101 12" lathe. I'd very much like to put a slotted cross slide on it for light milling work as I don't have a milling machine. I know where I can buy an Atlas Clausing slotted cross slide right now for a decent price, but it looks to have come from a larger machine. The female dovetail on the bottom of the slide is about half an inch wider and about an eighth of an inch deeper than the male dovetail on the top of the carriage.

So here's my question. Is it worth it to get someone to mill an adapter to fill in the larger dovetail until it fits the smaller one? There's certainly space for one. My gut says this would introduce instability and reduce rigidity but I'm not a machinist. What say ye, oh smarter and more learnéd? :D
 

4gsr

Global Moderator
Staff member
H-M Supporter-Premium
#2
You going to run into more problems than it's worth in the long run. I made one from a casting for a member here back earlier this year, I think it was for a 10" Atlas lathe, not sure though. The casting was designed to use over several sizes of lathes. The casting was stabilized for warpage but was nasty to machine! I would suggest buying a chunk of G-2 Durabar to make one out of. I would offer to sell you a piece of G-2 but at the moment I can't get my hands on anything small enough to make one out of unless you want to whittle down a 4" square to about 1" x 4". Ken
 

mephits

Iron
Registered Member
#4
You going to run into more problems than it's worth in the long run. I made one from a casting for a member here back earlier this year, I think it was for a 10" Atlas lathe, not sure though. The casting was designed to use over several sizes of lathes. The casting was stabilized for warpage but was nasty to machine! I would suggest buying a chunk of G-2 Durabar to make one out of. I would offer to sell you a piece of G-2 but at the moment I can't get my hands on anything small enough to make one out of unless you want to whittle down a 4" square to about 1" x 4". Ken
Yeah, it seemed to me like it was going to be more trouble than it's worth. The problem with making my own from scratch is that I don't have access to a milling machine. That's kind of why I'd have liked to find something relatively "turn-key". Unfortunately, this particular cross slide appears to be too large. I'll just have to keep looking.

Drill & tap your existing xslide for an angle plate then you can attach whatever you want. I used my compound to give me my vertical axis. To the compound I attached a 3/4" steel plate with a field of 3/8 x 16 TPI holes.

View attachment 141622
That's bloody cool! Very smart idea. Unfortunately, the cross slide on these old Atlas bench lathes is quite small. I doubt it would be rigid enough or large enough to mount something like that on. I'm definitely going to file that away for future reference, though. Thanks!
 

mephits

Iron
Registered Member
#6
Thanks for the links! I didn't know of Tall Grass Tools, so that's been added to my bookmarks for later. I lust after Metal Lathe Accessories' Atlas slotted cross slide, but as I mentioned above I have no milling capabilities myself nor can I find anything local to me other than commercial machine shops who're out of my price-range. I've chatted with Andy at MLA but he no longer has anyone he partners with to do milling.

When I came across an actual, Atlas-branded slotted cross slide I was hopeful, but the dovetail is significantly larger than the male dovetail on my carriage. Must have been for one of the larger Clausing lathes. My only thought was trying to adapt the dovetail down with an insert, but that idea strikes me as a bad one. Perhaps something will come along.
 

Randall Marx

H-M Supporter - Premium Content
H-M Supporter-Premium
#8
Hi Hurley and welcome!
How much are you calling "significantly larger?" I'm wondering if it is such that a well-fitted gib would be sufficient to take up the extra width. You would need a gib anyway so that you can adjust for wear and for rigidity. I've been considering the MLA slotted cross slide for my Atlas/Craftsman 12" lathe, but have no good access to milling capabilities to finish it. I followed Savarin's build on-and-off. He did a GREAT job and I've been considering doing something similar to that.
Good luck with whatever you choose and please share it with us. We LOVE pictures! :D
-Randall
 

gi_984

Active User
Active Member
#9
Perhaps a forum member within a reasonable distance from you will mill it for you. Might be cheaper shipping to next state over compared to across the country.
 

mephits

Iron
Registered Member
#10
Randall, the female dovetail is almost three quarters of an inch wider and an eighth of an inch taller than the male dovetail on top of the carriage. That's a bit much for a gib to take up. That's what got me thinking about some kind of adapter. Sort of a smaller male dovetail nested inside a larger female dovetail. But I think this would introduce slop and be less rigid. If I can find someone relatively local who's willing to mill one of Mr. Lofquist's slide castings I'd be perfectly happy with that, but I've not found anybody yet. It's early days, though. I don't even have the lathe in it's final, working location yet.
 

entityunknown

Active Member
Active Member
#11
I just wanna say that I made my cross slide dove tail for my Grizzly G8688. I just need to drill the holes in the cross slide but there's a guy on Youtube that did this mod for his Grizzly based on the Craftsman dovetail. Search "G0768 Compound Modification" and you can see what he did. It looks great and I look forward to testing it out but I can't see how it will fail. It's a wonderful design!

So how could this help you? Well I made the dove tail setup on the lathe just as the guy did and most lathe parts are built on a lathe so you should just be able to do this yourself? You do need a functional compound to make the dove tail but you could always take off enough material then use an angle file to shape a dove tail in.

With a carbide insert tool and 2" cold rolled steel, I had my all in one dove tail/base for the compound made in what would have been about 2 hours at n00b skill level with a pretty decent finish. With those cheap carbide tipped soft steel inserts, I had an extra 4 hours into it, tons of chatter, 3 tool breaks, and a terrible finish which I needed the inserts to finish and clean up the dirty work.

The only real problem was how close your tool holder and tool will be to the chuck teeth but with a lil care and probably a shop magnifying light, you'll be safe ;)
 
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mephits

Iron
Registered Member
#12
Thanks for the video entityunknown, but unfortunately, I'm not looking at replacing the compound. I'm looking at replacing the cross slide; the part the compound mounts to. Check this photo ( https://i.ytimg.com/vi/0lsZSF4MTvw/maxresdefault.jpg *) to see what I mean. On the left is the standard Atlas cross slide with the compound removed and on the right, a factory-original Atlas T-slot cross slide. I have a source for one of these factory-made slides, but it's too big for my lathe. That's the dovetail I was talking about adapting.

I'd actually prefer to have one of Metal Lathe Accessories' Atlas T-Slot Cross slides ( http://www.statecollegecentral.com/metallathe/A-11.html ) but I have no milling capability at the moment, nor have I found anything local that isn't a commercial shop charging commercial rates.

May I also say that my opinion of Grizzly tools just went down a great deal from watching the video you referenced. That's a terrible lathe design and very chinzy-looking parts! I know they're just rebadging import equipment, but they could at least take a bit of time to think about what they're potentially selling before slapping their name on it. I'm a total Newb and I can tell that's crap.

* Note that this linked photo is from one of Lyle Peterson's (Tubalcain / MrPete222) YouTube videos. I claim no ownership and use it only for illustrative purposes.