# Milling Attachment For My 7x12 Mini Lathe



## TTD (Jul 31, 2015)

Wasn’t sure what forum I should post this in, so Mods please move if needed…

As much as I would dearly LOVE to have a proper milling machine, current finances won’t allow that to happen for at least another year . So, my next best option was to buy or make a milling attachment for my little Craftex 7x12. I looked at the one Busy Bee sells specifically for this lathe http://www.busybeetools.com/products/milling-attachment-for-lathe-cx704.html , but wasn’t overly impressed with it for the price, not to mention the geometry was wrong for a couple specific jobs I needed it for. Well that settles that then…guess I’ll be making one.

Searched around the ‘net looking at different designs, but most (if not all) had the vice/material hanging wayyyy out over the cross-slide and in mid-air…not the most rigid configuration and uses up a lot of space - 2 commodities the 7x12 doesn’t have a lot (or enough) of to begin with. So I took a bunch of measurements of the lathe, sat down at the computer and proceeded to draw up a set of plans that would work for what I wanted to do. Once I was satisfied with the design (after numerous tweaks) I picked up some metal from Metal Supermarket in Ottawa and it was finally time to “git-r-done”.

Like most designs I have seen, I am using the lathe’s compound mounted to a ½” thick angle plate for the Z axis, and a small, used milling vice I picked up attached to the compound via an adapter plate. Right off the bat I needed to mill a pocket in the bottom part of angle plate and another pocket on backside of adapter plate to fit the tool post section of compound, but how does a guy with no milling capabilities yet go about this? Now, normally I would try to jerry-rig some sort of contraption together, hack my way through it and just try to deal with what would undoubtedly be a sub-par job…sounds stupid I know, but I would prefer to struggle (to a point, mind you) with an inadequate tool I built myself rather than bother other folks with my piddly projects or problems. This time around though, I wanted/needed the job done right and accurately if I wanted any hope of it being accurate once done. Sometimes a fella has no choice but to ask for help. Thankfully and  luckily (for me anyways), forum member Greg (a.k.a. f350ca) only lives about 30 minutes from me and said he could help me out. I am SO glad he did! Actually, he did ALL the major machine work for me seeing as he already had it set up, squared, etc - all I did was supply the drawings and the metal. Very nice work, VERY fair price and a helluva nice guy as well! Thank you once again, sir!

Once I had all the pieces back home, I drilled/tapped my compound 10-32 (6 in total) to hold adapter plate and started assembling. The low profile SHCS’s you see are just to keep swarf out of holes while working on the rest.



All pieces finished and ready to assemble. Angle plate, adapter plate and clamp nuts all made from ½” thick CR 1018 flat bar:



I kinda figured there would be a hiccup somewhere along the line (seems there always is...), and true to form there was, albeit a minor one - the 2 holes in vertical section of angle plate to attach compound are tapped ¼”-28 and wouldn’t ya know it, all I have left here is 20 TPI…not a single 28 TPI to be found anywhere…. Will get a bunch later today. Anyways, here it is all assembled and (mock) mounted to lathe:








Centerline of mounting bolts on cross-slide for compound lines up with center of vice mounting plate…just enough room to allow vice to fit in pocket. FYI, I needed that pocket in order to lower vice far enough to use my ½” dovetail cutter on a 1” thick breech…leaves a whole 0.060” to spare!! 



I still have a few little things to do like mount a dial indicator for precise Z axis measurements (learned the hard way not to trust the graduated dials on a cheap, Chinese lathe - sometimes they work, sometimes not so much…on mine anyways) and maybe paint or most likely blue the pieces to slow down the rusting process. I admit that for a 7x12 she’s a fairly bulky unit (just a hair over 11lbs) and might be a bit cumbersome at times depending on what I’m doing, but nevertheless it should prove to be a useful addition for what I want to do until I can afford a proper mill.

Now, to just find the time to use it…

Thanks for looking, hopefully it’ll give some ideas to someone else in the same boat as me!


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## T Bredehoft (Jul 31, 2015)

Glad to see you mounted it directly on the cross slide, didn't attempt it on the compound where there are too many joints for rigidity.


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## f350ca (Jul 31, 2015)

Was a pleasure helping you out Todd.


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## Bill C. (Aug 3, 2015)

If you have the time make some drawings or scaled photos for those who would be interested building their own. I like your design. Thank you for sharing


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## schor (Aug 3, 2015)

Nice work there Todd.


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## TTD (Aug 4, 2015)

Bill C. said:


> If you have the time make some drawings or scaled photos for those who would be interested building their own. I like your design. Thank you for sharing


Drawings???

As long as you use the term loosely, then yes I do have some, but be forewarned: I only used Sketch-Up as I don‘t have a proper CAD program anymore so “chicken-scratch” or scribbling might be a better description…. Other than that, I have no problem at all posting them for others to see & use as this is one of those very rare occasions where I actually seem to have something worthwhile to contribute here instead of always looking for info, but now you are all going to see just how “non-technical” I really am!… . Pics are definitely NOT engineer grade by a long shot, but all the relevant info is there…I think(?). I spent enough time on the computer drawing (and re-drawing) them that they make perfect sense to me, but if anyone has any questions, by all means fire away and I’ll do my best to answer them.

Not sure how to convert them to PDF (bit of a Techno-tard with computers), but hopefully these will work for you. If not, somebody may have to hold my hand and walk me through it…lol










OK….now for some issues I found. In the first pic above you’ll notice that the heads of 10-32 SHCS need .045” shaved off to fit flush with plate. I did that due to the pocket milled on backside which fits compound where tool post usually resides. Technically, there IS enough room left to counterbore for a full height 10-32 head, but it only leaves .079” of meat left which, right wrong or otherwise, I didn’t think was enough. If I had to do it over again, I think I would make the mounting plate out of 5/8” thick material. That way I could just mill the pocket a little deeper, still have enough left for a full depth counterbore while at the same time eliminating the need for the shim I currently need to support the top 2 screws.

The gap I mentioned above:



Also, the top two 10-32 thru-holes in mounting plate measure .968” c-t-c…. it might be a good idea to shrink that number to around .750”-ish c-t-c. When I drilled/tapped these, the one that’s on the same side as gib actually comes out pretty well centered right on the edge of gib…something to keep in mind. A 1” long SHCS fits perfect without actually protruding into dovetail area so no worries in that respect, just be careful if drilling it while compound is still attached to its base like I did (I held base in cross slide vice on drill press while drilling/tapping compound). Luckily I caught this little boo-boo before forging ahead and made sure I stopped right before breaking through.

Arrow is where hole will come through if using dimensions in pic 1:



The only other issue I’ve had (so far) that I can think of right now is that the two factory M6 cap screws used to attach compound to cross slide will be too long if used with attachment. On the compound the threads stick out .250” from bottom, while on the attachment they stick out around .400” IIRC and will bottom out long before the attachment tightens up. I picked up some M6x16 and trimmed them to the proper length with a cut-off wheel in the Dremel.

So as you can see, it’s far from a perfect design. Having said that though, the few minor issues that I’ve come across so far don’t really affect the performance, but would have saved some work in the beginning (shaving down cap heads, shimming gap, etc)… although almost drilling through into the gib would have irritated me to say the least. Should have been a little better, more thorough planning on my part for that one no doubt.

I got a chance to try it out last night for the first time in some 6061 aluminum as I started making an indicator holder for my new attachment. Granted, I took it easy for her maiden voyage only taking cuts from .010”-.015”, but….Ooooh, I like it! So much better than my “caveman mill” I use to (very sparingly) use - cheap drill press with a cheap cross slide vice from Princess Auto….now THAT setup had  some “interesting” moments I’ll tell you!

Seemed to work quite well with no chatter and felt as rigid as can be expected from a 7x12, but like a said, I was taking it easy just to make sure everything “settled in” before really working it. To help with the rigidity of the setup, I think I will loosen the 4 clamp nuts and move the vice up so that the bottom clamp nuts will be flush with end of vice. This of course depends on the size of cutter and/or material I may be using. My thoughts are this will allow the compound to fit fully on its base and then I will have all 3 gib adjustment screws pretty well supporting gib…I would think that could only help the situation?

Pic showing the room for adjustment (5/16” end mill in lathe) :



If you are still awake to read this, I apologize for the long-winded post. Hope this helps answer a few of your questions!


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## Downunder Bob (Jun 16, 2016)

TTD said:


> Wasn’t sure what forum I should post this in, so Mods please move if needed…
> 
> As much as I would dearly LOVE to have a proper milling machine, current finances won’t allow that to happen for at least another year . So, my next best option was to buy or make a milling attachment for my little Craftex 7x12. I looked at the one Busy Bee sells specifically for this lathe http://www.busybeetools.com/products/milling-attachment-for-lathe-cx704.html , but wasn’t overly impressed with it for the price, not to mention the geometry was wrong for a couple specific jobs I needed it for. Well that settles that then…guess I’ll be making one.
> 
> ...



Excellent job, Love your idea of mounting it on the inside of angle plate, getting the action over the middle of the cross slide, must be a great improvement in rigidity I might try to scale up for my new lathe 12 x 16 when it arrives, I'd love a decent mill but simply don't have room so will have to compromise.

Thanks for posting.

  Bob


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## T Bredehoft (Jun 16, 2016)

Great write up and marvelous job. Just a suggestion, add a couple of gussets, triangles to fill the corners of the inside of your angle plate, small enough not to interfere with long pieces in the vice, but long enough to give support to the angle plate. A couple of 1/4-28 cap screws in each side would be enough, just to secure it.


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## Billh50 (Jun 16, 2016)

I saved all the  photos in case anyone wanted me to put them into an actual blueprint and all together in a pdf.
With the authors permission that is.


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## Andre (Jun 16, 2016)

Is that an airgun breach you're machining in the first post (5th photo)?


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## TTD (Jun 18, 2016)

Billh50 said:


> I saved all the  photos in case anyone wanted me to put them into an actual blueprint and all together in a pdf.
> With the authors permission that is.



No problem at all, Bill....thank you very much for doing that!

Now that I've used it for awhile, one minor change I would make to original drawing is the location of the top two clamp nuts. Instead of making them 3" c-t-c between  top/bottom clamp nut locations, I would place them @ 2.72" apart c-t-c (same as the width I needed for my particular vice). Then I could easily change vice position from vertical to horizontal depending on material size/operation needed without having to move top clamp nuts every time.

Don't know why I didn't think of that little detail right from start....


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## TTD (Jun 18, 2016)

Andre said:


> Is that an airgun breach you're machining in the first post (5th photo)?


Yes and no....yes it is an airgun breech, but no, I didn't machine that particular breech. Have done two since that pic was taken, but not the one in photo.

Had a buddy from an airgun forum I frequent make that one for me before I even had a lathe. Used his breech as a guide while making a radius cutter for my wee lathe to check for any clearance issues. Pic was just a mock-up of how my eventual "finished" setup would look & work.


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