# Milling on a lathe



## ttabbal (Feb 20, 2018)

So, in my thread about beginner projects a lot of mill projects are creeping in. I don't mind that, it's nice to get ideas, but now I want to mill things.  

So I know the attachments are not rigid enough to do heavy milling. I'm thinking little slots, keyways, etc.. Mostly aluminum, small cuts on steel I'm sure will come up. I ran across this Grizzly adapter... 

http://www.grizzly.com/products/Milling-Attachment-for-G4000/T10721

It's small so it will keep me honest, and the hole spacing looks like it might well bolt up to my PM 1127 cross slide. I'd likely need to make or buy some T-nuts, and perhaps buy or build something to clamp work to the table. Along with something to hold a mill cutter and a couple cutters.


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## Mitch Alsup (Feb 20, 2018)

Issues::

1) I have a similar adapter for my Taig mini (or micro) lathe::
1.a) it is difficult to hold things well enough to mill <accurately>
1.b) the milling performance is <best I can say> slow
1.c) it is hard to see what you are milling
1.d) I did mill some slots in 6061 Al for a telescope I built 19 years ago
........just about the only use that thing ever got.

As to 1.b: I can use a hacksaw and a file at a faster rate than I can mill in the Taig--which was very frustrating

But give it a try, as the cost is "not that much".

I ended up with a real lathe (G4003G) and a real Mill (G0730).


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## ttabbal (Feb 20, 2018)

Yeah, I'd love a real mill. That's not happening anytime soon. I could swing the parts to try the adapter. I could wait a bit and get a mini mill, but even those start around $700. And at that point you get close to a decent benchtop mill for a little more and so on..


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## cg285 (Feb 20, 2018)

my grandfather built his shop and house in 1923. he put this lathe in the basement of the house. he had a machine shop/auto repair business until 1986 when he died. as a teenager i saw he had a bridgeport mill and i asked him what did he do before that for milling. he looked at me like i was an idiot and said "well the .... lathe of course" he never ceased to amaze me on what he could produce. point is a lot can be done on the lathe


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## TTD (Feb 21, 2018)

Hi ttabbal,
I started out (as I’m sure most here have) pretty much exactly like you…a few little (useful) projects on the lathe to get familiar with both machine & process/order of operations. And, like you, it wasn’t very long before I realized that I NEEDED a milling machine. I couldn’t (& still can’t) afford a proper milling machine, so a milling attachment for the lathe was my only option, knowing full well going in of its limitations.

The problem I found with most, if not all,  “store-bought” milling attachments (& even most of the home-brewed ones I looked at while researching) is they tend to place your work piece waayyyy out past the crosslide, making for a chatter-inducing, non-rigid setup, not to mention drastically reducing your workspace (especially when working parallel with lathe axis).

My solution for this was to make my own  milling attachment for my little 7x12 lathe that would hopefully remedy the problems noted above. I won’t clutter up your thread with a bunch of pics of my setup, but here is a link to the build if you are interested: 
https://www.hobby-machinist.com/threads/milling-attachment-for-my-7x12-mini-lathe.37410/#post-405613
…and first project using attachment (indicator holders): 
https://www.hobby-machinist.com/thr...ct-with-milling-attachment.37673/#post-322506

Since that original build post, I have used the attachment on everything from Delrin/Acetal to 4130 CrMoly tubing & everything in between with no problems. Still have to be mindful of your setups, DOC, machine’s ability etc, etc.., but it works good!

Hope this helps rather than confuse your decision more!


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## British Steel (Feb 21, 2018)

Like TTD I improvised until I bought a milling machine - I mounted the topslide  (compound) from my lathe on a large webbed angle plate, then mounted that on the cross-slide  (blessed with T slots), made a long T nut for the topslide's toolpost mount to bolt a small vice to. This gave me about 10x5" of x and y travel (and i could use the cross-feed for powered x-axis) and, with the tailstock brought up to support was *reasonably* rigid.
I used (1/16" steps) collets in the spindle, which limited me to 7/8" shanks, plenty big enough with everything flapping around!

I mostly used that setup to cut short keyways etc., worked pretty well.

Dave H. (the other one)


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## ttabbal (Feb 21, 2018)

Thanks for posting the details of your design @TTD. I thought it seemed like hanging it off the side of the cross slide would introduce flex where one would not want any. I figured the idea was to allow for travel of the work below the cross slide plane. But the stickout plus a vise mounted on there could get excessive. I suspected that clamping the work directly to the table of the commercial unit might help, but then setup becomes a bit more tiresome. 

I don't think that the unit I linked would mount parallel to the ways. That's a design consideration I didn't think of. I could see it being useful though. If I used an angle plate that allowed for the bolts to be in a square pattern, I could mount it in any 90 degree orientation. I see some that use a rotating base, but I suspect that's another flex point and I think I'd rather avoid that for now. 

I'm not in a huge hurry. I don't have any milling cutters or a way to hold them other than the lathe chuck. And I keep reading that it's not a good idea to do that. An MT5 end mill holder isn't terribly expensive, add some all-thread for a drawbar and it should be pretty sturdy. Or there's always a collet chuck, which I already have reasons to want. Though it does push the price up a fair bit and I'd need collets.


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## ttabbal (Mar 8, 2018)

I decided to pick up the Grizzly adapter. It fits, parallel to the ways. So I can have the table face me or away from me, but not toward the chuck. I'm thinking of building an adapter to mate it to the lathe so I can face it whatever way I want to. 

The idea right now is to buy/make some t-slot bolts/nuts to hold a piece of plate steel down to the cross slide in a square pattern so I can rotate it, and have a bolt pattern that fits the milling adapter. I'm thinking about 1" A36 with a ground finish. Any reason that might not be thick enough? Then perhaps adding a spacer and building a solid mount for my tool post for those times the compound is too flexy.


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## ttabbal (Mar 23, 2018)

So I've been tossing options around and think I have most things ready to mess with. I ran into a question I thought would be good here. 

Many people use mills for drilling. Many are advertised as drill/mills, the smaller ones anyway. If I wanted to drill in this setup, perhaps on a flat workpiece, could I use my tailstock drill chuck in the headstock with the proper MT5/3 adapter? I know end mills need to be positively held with a drawbar in that configuration. Do drills? I've never seen people mention it, but that might be because it's too nutty for most people to think about in the first place. 

This is partly because my drill press has so much flex that I almost need more travel than my 1" indicators have to measure it.  But mostly because now that I thought of it I almost have to try it, if only to see that I hate it. But I want to make sure I'm not likely to break equipment or people doing it. And yes, I'm planning to get a decent drill press or mill or both.


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## mikey (Mar 23, 2018)

ttabbal said:


> If I wanted to drill in this setup, perhaps on a flat workpiece, could I use my tailstock drill chuck in the headstock with the proper MT5/3 adapter? I know end mills need to be positively held with a drawbar in that configuration. Do drills? I've never seen people mention it, but that might be because it's too nutty for most people to think about in the first place.
> 
> This is partly because my drill press has so much flex that I almost need more travel than my 1" indicators have to measure it.  But mostly because now that I thought of it I almost have to try it, if only to see that I hate it. But I want to make sure I'm not likely to break equipment or people doing it. And yes, I'm planning to get a decent drill press or mill or both.



Sure, you can use your drill chuck on your lathe with the proper adapters. Do what you need to do to get the job done - just don't damage your nice new lathe. By the way, I vote for a new mill and a good used drill press.


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## agfrvf (Mar 23, 2018)

I was looking into surfacing the side of the bigger HF cross slide vice and mounting that to the compound mount.


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## ttabbal (Mar 23, 2018)

Sounds great @mikey. You have my address, let me know when to expect them.  

That's the long term plan, but it will be a while before new machines get added.


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## menace (Mar 23, 2018)

Once upon a time I tried that on my SB9. I made a 1/2” x 4” angle iron 4”long,secured to T slot on compound! I cut holes in the vertical face of the angle iron and a few slots also for mounting and adjusting items to be milled. You can get creative with this keeping it close to centerline of compound making movable horizontal jaws to hold the work using the holes and slots to fit the workpiece. On top jaw drill and tap 2 or 3 vertical holes and tap fine thread for holding screws, like the ones on tool holders that you can tighten your workpiece with ! As far as holding the end mill,  measure the horizontal length of the part of the jaws that will extend below the diameter of chuck hole! Take the depth length from back of jaws inside chuck hole to end where diameter narrows  and mark the length on end of round stock continuing with horizontal chuck jaw length marking this additional length on stock. Now you have 2 consecutive marks, chuck unmarked end of stock and turn hole depth part to diameter of hole, tight fit. Next turn the horizontal chuck jaw length approximately .250” deeper than first cut (chuck hole diameter). Now you have 3 diameters on stock, turn stock around and mount into chuck and tighten. It should fit nice and tight, you might have to tweek a little. You now have a thicker stub outside the chuck which can’t pull out or push inward. , leave it about 2” sticking out. Put drill chuck in tail stock. Choose your shank size for endmill according to what your lathe size can handle. Buy a Weldon shank, centercutting endmill with flat ground on shank of size you decided. Place endmill on top of stub extending from chuck parellel and horizontal with Weldon flat visible. Measure from center of flat to shank end of endmill, double measurement and mark stub from the end including center of flat from end of stub . Mount endmill into tailstock drill chuck real tight,bring it to stub end and slowly use endmill to drill shank hole to depth of mark on stub make it exact ,you have to peck drill this hole to relieve chip buildups. Get a set screw and drill and tap mark for center flat. Put endmill into hole,line flat with setscrew and tighten! Here is your endmill holder! I know this was long winded but once you understand it,you’ll make it in a few hours! I’ve made quite a few. Your lathe is limited, save for the biggest milling machine you can fit in your shop! Good luck.


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## British Steel (Mar 25, 2018)

ttabbal said:


> So I've been tossing options around and think I have most things ready to mess with. I ran into a question I thought would be good here.
> 
> Many people use mills for drilling. Many are advertised as drill/mills, the smaller ones anyway. If I wanted to drill in this setup, perhaps on a flat workpiece, could I use my tailstock drill chuck in the headstock with the proper MT5/3 adapter? I know end mills need to be positively held with a drawbar in that configuration. Do drills? I've never seen people mention it, but that might be because it's too nutty for most people to think about in the first place.
> 
> This is partly because my drill press has so much flex that I almost need more travel than my 1" indicators have to measure it.  But mostly because now that I thought of it I almost have to try it, if only to see that I hate it. But I want to make sure I'm not likely to break equipment or people doing it. And yes, I'm planning to get a decent drill press or mill or both.



A drawbar isn't so essential for drilling, milling yes because of the risk of and endmill pulling the chuck from the taper, but the pressure from drilling should keep it seated and there isn't the cyclic side-load that tends to work tapers loose when milling so you should be good to go with a taper-shank drill or a drill chuck in the spindle taper. 
In a pinch I've drilled from the headstock, and then offset a boring bar in a 4-jaw chuck for a more precisely round hole - that's a hassle to adjust, trial bore and careful measurement followed by adjusting the 4-jaw with a dial indicator against the tool - a reamer the right size would have been a lot easier and way, way quicker! Anyone have a 30.05mm reamer handy?
One thing I found handy was when drilling a row of holes at precise spacing: drill the first then loosen the vice/clamping, leave the drilll in the hole and wind the cross-slide out (and in to take up backlash) clamp up and then retract from the drill, advance cross-slide by the hole spacing and repeat. Something I couldn't do on my cheap Chinese baby drill-press, particularly with the 7x3 channel I wanted accurate holes in (still haven't finished that press frame!)

Dave H. (the other one)


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## ttabbal (Mar 26, 2018)

So, I got some work done on it over the weekend. Drilled and countersunk the holes to hold down the adapter plate and the mill adapter. Found the T-nuts a bit tall, ground them down. Then discovered that I need longer screws for the milling adapter. So I'll pick those up today. I also discovered I really need some nicer countersinks. These chatter too much. And that my drill press is worse than I thought, the pulley set screw appears to be stripped out, so the motor pulley jumps around and makes a ton of noise. Doesn't have much torque either, as one might expect with the pulley loose. It doesn't help that the operator also has more than one screw loose.   

In the mean time, I figured I'd look at the end mill adapter I ordered. MT5 and end mill side look fine. But the box it came in and the website said the draw bar is 1"-8 thread. Hmm... ok, seems like overkill, but I've seen that size all-thread locally. Go to get some, just to find out they have it, and washers, but no nuts that size. So... why stock the stuff if you can't connect it to anything? pffttt.. Whatever. It was overpriced anyway. I have a lathe, so I instead start getting stock out etc to cut some threads. Only then do I look closer and realize, that's not a 1" hole. No way. 

Turns out, it's a 5/8 and I didn't discover it until after all the stores were closed on Sunday night. facepalm. That's what I get for trusting the spec. Not that I could have actually done anything with it, but still felt like a kick in the junk. Hope you all had more success with your projects!


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## ttabbal (Mar 27, 2018)

Well, I got it mounted up. I think it might be the most accurate pattern drilling I've managed at home, but I'm not happy with it. 

The bolts to hold the plate to the cross slide are off just enough that getting the last bolt in isn't happening. Combined error is just too much. Well, 3 isn't horrible and it's stable, so figured I'd mount up the milling adapter. Those holes ended up working well and all 4 are installed. Feels solid, but I can tell it's not quite square. Indicator tells me that it's off about 0.03 over 3". Pfftt. I think slots and things where depth isn't crucial could be done. Perhaps shiming the table between the vise/work could be good enough. I know this type of set up is never going to be super accurate.


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## Tozguy (Mar 27, 2018)

Would love to see some pictures ttabbal.
This is how I managed to do some accurate pattern drilling on my lathe,


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## ttabbal (Mar 27, 2018)

I did forget to post pictures.  

I also realized that I didn't indicate the vertical, it's under 0.001 over the entire movement range. So that's good at least. 





Just for fun, here's my drill press... It's, um, not so good. I know what they say about a craftsman blaming his tools, but I think an exception can be made for this thing.   I'm willing to take more than half of the blame though.


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