Vertical milling attachment vs combo lathe/mill??

i'm going round and round trying to decide on a first lathe. the initial goal with be parts related to vintage motorcycles and then whatever else comes along. Initially i was looking at the optimum tu-2506v (25x500 x26mm spindle bore) with a bolt-on BV20AF mill combo. but the minimum speed is 150 for threads and the few reviews I've read suggest milling combo machines end up being quite limited. And i think the quality may be a bit variable on these lathes.

today's idea is an AL-320 (320x600 x 38mm spindle bore)- much sturdier machine and 60rpm minimum speed - and add a vertical milling attachment to it. that overall costs about the same as the option above, for a much better lathe (I think). but the milling capability will be more limited.

so the question - is a vertical milling attachment on a larger sturdier lathe going to be a lot worse than a smaller lathe with the combo attachment.? is this trade-off worth it? truth is I have no immediate plans or specifications for the mill but a month ago i did and had to get someone else to do it for me.

in case you were wondering, the budget has been increased significantly at least twice. it cant go much higher as i still need tooling etc.

thanks for any comments you can make.

Mike

Since the dawn of the industrial age man has tried to create the perfect lathe/mill setup

None have ever broke the barrier and they are all a compromise, some quite amazing setups have been tried

At the very least, get a good lathe and then take it from there

Most lathe based milling setups lack rigidity and require frustratingly light cuts but with patience much can be achieved. My initial optimism of milling in the lathe was seriously tempered by actually doing it. A milling machine quickly rose to the top of my wish list and when I got it milling became a much more satisfying activity. Hobby mills are still limited compared to an industrial machine but one of the things that make a mill work well is rigidity and this usually comes from a heavily built machine and hobby mills are usually a bit on the light side but are still in another league compared to a lathe based setup.

Mike

As Ady1 says lathe/mill combinations are always a massive compromise and rarely truly satisfactory on milling duties.

Probably the least unsatisfactory style is the type with a self contained milling head affixed to post at the rear of the lathe bed at approximately mid travel. The top two pictures on this page from Tonys invaluable lathes.co site **LINK**. show a typical example of this style that is generally accepted to be well executed and perform well given the inevitable limitations.

The major issues are work-space volume and the engineering compromises needed to make something affordable. By proper milling machine standards the heads are invariably light duty. Necessarily so as the bolt on column cannot match these stiffness of a proper mill. Even when, as in the case of the Emco, the head and column are a straight lift from a small bench mil the purpose built milling version ends up significantly stronger and able to handle much heavier cuts. The common lathe bed V and flat configuration has stiffness issues to when compared to a purpose built mill. Lathe saddles generally need to be set to move more freely than milling table which doesn't help. Although a boring table will be fitted to the cross slide to carry milling jobs its inevitably smaller than a purpose made milling machine table. The cross slide ways are much smaller and less stiff too. Downfeed arrangements are rarely fully satisfactory when compared to proper mills. But that is something where compromises often need to be accepted in smaller, affordable mills anyway.

Even given its limitations such a set up is still a major step up from a vertical slide and pretty effective for small, modellers style, work. Even the professionals have trouble for real size work e.g. **LINK** , and http://www.lathes.co.uk/adcock&shipleycombination/index.html. The milling capacity is small given the size of the machine. Worth a look at the combination machines section over at lathes.co to get some idea of the physical limits.

I seriously doubt that any such combination can have the stiffness and work capacity needed for vintage motorcycle work and the like. Its trite, but true, to say that a Bridegport is about where you can stop worrying about workspace capacity for any 12" to the foot scale jobs that you can lift by hand without help. I always feel its better to scale down from a Bridgeport as you figure out what the smallest machine that can reliably handle your planned work is rather than to try and scale up to something that the job can be squeezed onto. Do remember proper mills of necessity sprawl and take up relatively more space than a lathe primarily because all the work and tool holding equipment has to go inside the nominal workspace.

Clive.

Edited By Clive Foster on 11/12/2018 12:00:26

I agree with all the negative comments about milling vices and combination machines. Both are very constricting compared with separates. But both are useful if you are short of space and can put up with being restricted to light milling on smallish objects only. It's amazing what can be achieved on limited kit by determined operators with imagination and skill. My advice is buy a combo if you are short of space, never buy one to save money.

On the subject of threading, it's true that a minimum speed of 150 rpm is awkwardly high for threading under power, though it's not such a problem if you use carbide inserts and run the lathe in reverse. Most Chinese lathes can do this.

Another good alternative if you're not doing loads of thread cutting, is to make a hand-crank to grip inside the spindle so you can turn the lathe by hand. A hand-crank gives total control and - as long as you haven't got several long threads to cut - it's not seriously tiring. The downside is threading takes longer, but if you only need to cut a few threads every so often and aren't in a hurry, it does a perfectly good job. It's also less stressful because no way will you crash the saddle into the chuck and break something! Worth knowing also that most small threads are cut with taps and dies; lathes are usually reserved for big diameters and/or unusual threads.

Dave

The addition of a milling column to a lathe has always looked spindly to me. For milling in what is primarily a lathe, the vertical slide has always seemed to me far more rigid.

I've wanted a milling machine for ever, but with my double-swivel vertical slide I've so far always found that for model engineering I can actually manage with what I have - so the purchase of a mill goes onto the back burner yet again.

Certainly the wide cross slide on my WM250V is far stiffer for milling than the same setup on the Myford Speed 10 I had previously, and the fine powered cross-feed allows a very good finish. Metal removal rate and envelope are both limited, of course, but - as I said - I've so far found I can manage. There may still came a time when that changes but it's certainly a good working start.

Further to Clive's comments re scaling down from a Bridgeport. I do a lot of vintage bike stuff, mainly pre war. I have a Bridgeport and a 14"x40" lathe with 40mm spindle bore. For me and the work I undertake this combination is ideal.

The problems come when deciding what you want for machinery and start with space and budget restrictions. Good Luck and please do let us know what you buy.

Before you go making any decisions about using a vertical slide or the cross slide to hold work for milling take a closer look at the AL320 you are thinking about.

Unlike the smaller hobby lathes it does not have a slotted cross slide and the surface is not even flat across the whole depth so you are going to have to start drilling the machine to mount a slide and there is no easy way to mount work direct to the cross slide.

I would also doubt that it has the flat area at the back of the bed to mount a column which a lot of the hobby lathes do.

Don't forget to get some decent lathe books and read them as part of your research

They help you focus on what matters

For myself Sparey was the bible in those early days

Edited By Ady1 on 12/12/2018 09:04:42

thanks for the very helpful comments. i think i'm getting a clearer picture. in a couple of days i've got some time to head back around the various shops and kick the tyres some more. currently i'm drifting towards the al320 option tho will check the cross slide and the back for a mounting area or other options. i am constrained on space and money so there are gong to be trade-offs. a Bridgeport is probably always going to be out of my range. But with so many forums posts where people talk about their first lathe being too small I'd rather not have that to look forward to.

when i finally put my money down i'll report back on what and why.

cheers

.

I'm in no position to advise on the matter, Mike

Until a few minutes ago I didn't even know what an AL-320 looked like.

I have, however, just seen this **LINK**

https://www.homemodelenginemachinist.com/threads/al320-lathe-mods-rebuild.26146/

Which you may find informative.

MichaelG.

Agree with the previous comments.

If the Cross Slide is not flat, and lacks Tee Slots, you cannot fit a Vertical Slide.

My Tee slots carry a Rear Toolpost, which IS useful.

Having said that, I found the Vertical Slide on my ML7 to be too flimsy. And the Rodney Milling Attachment which superseded it accentuated the lack of rigidity in the lathe bed. So I bought a Mill/Drill. Would have liked a "proper" Mill, but budget, and space, prevented that..

Have used a larger Vertical Slide on my larger Lathe (12 x 24) which replaced the ML7, but only for co ordinate drilling of a component that was too long to fit under the Mill /Drill.

If possible turn in the Lathe, and Mill in Milling machine. They are each designed to do he job for which they are intended. A small car is useless for ploughing fields!

Howard

Listen to people in the know.

Everyone above has said no. Just don't.

I concur x 100.

Buy a lathe.

Buy a mill.

End of.

Jason / Howard - re the cross slide lacking tee slots, there are a number of videos of people drilling/tapping holes into the cross slide to mount the vertical slide.... is this a bad idea? eg this: **LINK**

thaiguzzi - in an ideal wold, yes. I get the point that milling would be compromised. but i am constrained by space and money. so i'm looking for a viable start (lathe first) and maybe upgrade milling options later.

cheers

I did say in my previous post that you would have to drill the cross slide, some people are happy to do that others would not want to touch their machines. A lot will depend on where the holes can be placed and how much metal you have to cut into.

As I also mentioned and unlike the lathe in your video the AL320 looks to have the cross slide stepped up where the top slide mounts. This will limit what size vertical slide can be mounted and won't allow it to be positioned anywhere along the cross slide which is useful to allow you to get the longest movement for milling. The lower half of the slide would be quite thin so you are not going to get very deep threads into that.

Also think about working on parts that are larger than the milling slide will handle, I often fix large items directly to the cross slide making use of the tee slots. It would be possible to make up a sub table with matching stepped bottom but the thickness of the table reduces ctr height so what you gain in one way you lose in the other.

Edited By JasonB on 13/12/2018 07:56:01

thanks Jason - points noted. there is a vertical slide as an accessory for the al320 on the webpage **LINK** but I'll go and have a careful look at it in the morning.

That looks like the one in the video. Just had a quick look at the manual and the thicker area under the topslide does not look like you will have much to play with due to the large hole so it really comes down to how much metal there is to tap in the lower section.

tomorrow i'll go and measure the thickness of the lower cross slide section. obvioulsy thicker is better for tapping a thread into. any estimates of a minimum thickness that you would feel comfortable with?

Mike B1, what is your general location ? Always good to go and see other members set up to help you decide.

I'm in New Zealand Chris - Central Auckland... are you a kiwi?