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I've been threatening to get started on a CNC lathe as soon as Thor was complete. Thor is now basically done, so time to move onto the next project.
The design for the lathe is fairly straight forward. The part I am struggling with is what headstock / spindle to use.
Is it worth buying a standalone headstock from a parted out lathe and use this with a bunch of decent rails / servos? Suppose I could try and make something but not sure I can get the accuracy needed.
Thanks
Have you got a lathe or access to one?
What kind of tolerances can Thor produce?
Given the effort you put into Thor, I cant wait to see what you come up with this time for a lathe, tool turret on the cards?
I have my Emco 120 which Ill sell. Just not big enough for what Id like to do.Quote:
Originally Posted by Lee Roberts
Tolerances, not checked yet, should be doing some calibration cuts this weekend once I get a new table installed. I'm also aware that I have a slight offset in my Z axis, getting a bit of deviation across the Y plane, when measuring Z movement. This is due to the spindle clamp I am using, Ill probably replace it or machine something better than what I bought.
I have two main options for a lathe. One, use my massive metal structure that I used for referencing as the base for the lathe, simply bolt rails to its one side, install 3 carts each side, fabricate a simple X and Z Table. Toolchanger, multiple options, id possibly got for a non turret option as its easier (I think) based on a large working area.
The idea is that I get a headstock that I can then just add a nice high power servo motor to and go from there.
Another option is to form and cast another concrete structure but this is a lot more work. I may start with the metal structure, prove the concept, then convert it to Concrete (or make another a decommission this one).
Depends on what you will use it for. Have you thought of indexing and lather 4rth axis, all in one? LIke this one . basically that guy has his build log on the cnczone
http://www.theinturn.com/
So something like this on Thor? I am keen to do a 4th axis, so will certainly explore this. Estimated costs?Quote:
Originally Posted by Boyan Silyavski
PRICING:
InTurn™ MEGA Duty 4th axis US$ 2,950
InTurn™ ULTRA Duty 4th axis
Sealed Ball bearing model US$ 3,795 (introductory price)
InTurn™ Ultra-T
Tapered Roller Bearing model US$ 4,995 (Introductory price)
InTurn™ Tail Stock II US$1,495
Bicycle disc brakes, some aluminum, 700w servo motor , you machine the pulleys and so, some belts. So basically the extra controller may be or you figure another way to do it.
I find that really an useful thing to have
Explain more please ..... I should be able to machine most of this - not sure about design and bearing selection, not an area I understand.Quote:
Originally Posted by Boyan Silyavski
As far as i remember 7:1 ratio of a 700w servo motor. Hydraulic bicycle brake brakes and fixes at certain position when indexing. Bearings are fairly simple. They are so cheap now. Something like the rotating ball nut. A pair of oposing angular contact bearings with sufficient size. Thats it
Check his channel on you tube. There are 10 or so videos where he explains everything in detail https://www.youtube.com/user/Simpsons36/videos
The InTurn development thread can be found on the mach forums - http://www.machsupport.com/forum/ind...c,11422.0.html
IIRC lots of the design aspects were discussed, but it's been a while since I've read through the thread. It's certainly worth having a read if you've got a couple spare hours.
It's a good solution, but the downsides are lathe tool mounting, having to swap the belt to change speeds, and having to continually install/uninstall it.
I can see the appeal if you're limited for space, but I'd opt for a decent lathe.
Lathe spindles are not complicated. Spindle, housing, couple bearings. Job done. The problem is the spindle itself, as you either need to start with a big lump of metal and remove most of it, make it out of two parts and weld/screw it together, or get it forged. And if you want to use a Camlock chuck, you need to find the correct specification document with all the dimensions (Chuck specs are easy to find, but the spindle specs not so).
Off course, you could buy a spindle - http://www.posa-spindle.com/en/index or http://www.royal-spindles.com.tw/
There is the possibility of a headstock from a more hobby type lathe, but I'm not sure who would supply something like that in the UK.
Thanks. Good info.Quote:
Originally Posted by m_c
I sometimes see Boxford lathe headstocks (or similar) being sold for around £250 on fleabay. Is that not worth looking at?
I see the appeal of Inturn like 4rth axis if you are doing stuff like gears, pulleys, small intricate parts. Basically what i believe is worth having at home for a CNC lathe. Now if you want a CNC lathe for bigger parts that do not need indexing, i agree its not the best choice.
i am waiting for the day to come, but basically what i am going to do is fit to my mini lathe 700w servo motor, additional hydraulic disc brake from bycicle and thats it. Fit it in my machine. maybe change to bigger chuck.
Something like a boxford headstock would work. Ultimately suitable headstocks depend on how big a bit of metal you want to be able to fit through them. The bigger you'd like, the fewer and more expensive the options.
However, if you design it with a bolt on headstock (which you'll really want anyway for alignment purposes), then swapping at a later date won't be as big of a challenge.
My thoughts are something like these:-
http://www.ebay.co.uk/itm/BOXFORD-HE...YAAOSw32lYuejJ
or
http://www.ebay.co.uk/itm/MYFORD-ML1...8AAOSwxu5ZOIUw
Is the cheaper Chinese stuff worth considering - like this - http://www.ebay.co.uk/itm/Headstock-...MAAOSw8gVX2sAJ ?
I picked the Colchester Chipmaster as its a tool room spec lathe and had the spindle capacity that i needed. had a lever operated collet chuck as well. bonus :0)
I think I'd go for the Boxford or Chinese option. My original CNC lathe was based on an ML10, and I always thought the spindle was a bit noodly.Quote:
Originally Posted by Chaz
Before deciding on a headstock, you need to think about what size of bar you want to be able to fit through it.
ML10 limit was a 5/8" throughbore IIRC (I used an adjustable reamer to open mine up so I could fit 16mm bar in). That CJ16 should be 20mm, and a quick search puts the Boxford at 3/4".
That Boxford seems very nice. Nothing beats buying a complete head stock.
I'm tempted to buy this.
http://www.ebay.co.uk/itm/Smart-Brow...QAAOSwyltZWUgD
It's tatty, might work as a manual lathe, I Can then break it down and take / keep the headstock. Not sure if its worth trying to convert it, just use as is until I am ready to take the headstock.
Thats what i was saying, Mini lathe + servo motor and brake and fit inside the machine.Quote:
Originally Posted by Chaz
Cause once you restore it , it will be beautiful and difficult to salvage it for parts
So I went to go look at this machine. Lovely little machine - almost too good to break, the pics make it look bad. Turns out the guy is a professional photographer who happens to fix diesel generators and other stuff like that, nice guy.Quote:
Originally Posted by Boyan Silyavski
I may try and CNC the machine as it is, the headstock looks substantial, large bearings, meaty thing. Some play in the crossslide etc but not really a problem I think.
Considering a headstock alone (ignore the cheap chinese one) will be around £250, getting this for around £450 with some options is probably reasonable enough. It will work as it is now. I can fit a ballscrew in the centre of it or the front, there is space to mount rails if needed, so options exist.
The other question I had was around max spindle speed. The machine is rated to run 1200 max. Whilst not bad, for alu, higher is better. I cant find any details around the bearings used, any idea if this will be an issue to use this headstock to mainly machine alu?Quote:
Originally Posted by Boyan Silyavski
Did you see this? Ended a few days ago but didn't sell - worth making an offer maybe?
http://www.ebay.co.uk/itm/hardinge-c...AAAOSwXXxZSa2l
Ye, I did, thanks. Issue was its collection only and not close for me. But it certainly was suitable for what I was looking for.Quote:
Originally Posted by bikepete
So I have bought this Smart & Brown machine - a number of options exist. Will take a look once it arrives to see if I should just CNC it as it stands or do something else with it.