Slant-bed lathe question

[zephyr9900]

I was wondering last night--if 30 degrees is a good angle for the slant bed, why not 60 degrees? How about 90 degrees? Assuming linear ways, they are not dependent on gravity to keep them in engagement. Why not put the Z axis behind the spindle and have a vertical X axis? Am I missing something? The context is a small (Sherline-sized) homebrew with linear ways.

Thanks,

Randy

[Geof]

I think if you sketched up a concept and figured out how much material went into it the machine would be much heavier than a conventional machine. The basic frame structure would have to be L shaped. With a small machine such as you are considering this is probably no problem but with large industrial machines it could be a factor.

You are quite correct about the linear ways not caring about which way is 'up'. If you had a big reinforced concrete wall handy you could bolt a conventional machine to it and now you have it . Although it is likely that the weight of the machine itself would cause distortion leading to inaccurate operation. The bed of a lathe is machined sitting level, the casting has to sag a little between the supports but when it is installed and levelled for use the sag will be the same as when it was made. If you rotated it 90 degrees now the sag due to its weight will be perpendicular to the direction it was machined; the machine would be warped downward which is sideways from the conventional view. The original sag would turn into an upward bow which would be outward when looking at it hanging on the wall.

[zephyr9900]

Thanks for the reply, Geof. I just wanted to see if there was anything obvious that I hadn't thought of. Of course, on a large machine there would be significant gravity effects and that would take some FEA to get right.

But my machine will be tiny--the 3-jaw chuck in the picture below is 2.4" diameter. The lathe will use a couple of small THK linear actuators I got surplus a few years ago, and the headstock from my Sherline lathe on a spacer. Baseplate is a chunk of aluminum tooling plate. I will probably experiment with slant-beddedness by just tilting the whole thing up on some supports.

Best regards,

Randy

[Geof]

For a small lathe having the spindle close to eye level with the tool coming in from the top might make it very easy to use. Totally unconventional but you would not need to stoop over to try and see the tool and settings things up could be more convenient. This would probably work for big machines but the structural challenges are more serious.

This idea is about as far outside the box as the one I had a while back for an upside down milling machine. You would not need to worry about re-cutting chips when interpolating a hole or cutting pockets .

[gridley51]

In the early days of cnc,Dean Smith & Grace a well respected British lathe buider,built such a machine as you describe.They called it a Monarch,and it was an extremely rigid machine.Had some form of concrete base.By the eighties you couldn`t give them away,due more to the GE550-1050 controls more than anything else.I haven`t seen one in years and sometimes wonder if there are any left.
Mark

www.ems-fife.co.uk

[zephyr9900]

Originally Posted by Geof ...with the tool coming in from the top

Ooooh, that's even more out-of-the-box than I was thinking. I like it! The linear ways won't care what direction the cutting forces are coming from. Instead of a rear cutoff toolpost (the only rear thing I've seen on Sherlines) a rear cutting post. Since I don't plan on turning anything more than about 1/2" diameter on this lathe (specifically small-scale model railroad wheels) there won't be a problem fitting front and back toolposts. And maybe one more in the middle for drilling and face work.

Thanks again, Geof, for helping rip that box apart...

Best regards,

Randy

[zephyr9900]

Originally Posted by gridley51 In the early days of cnc,Dean Smith & Grace a well respected British lathe buider,built such a machine as you describe.They called it a Monarch...

I haven't found any pictures of that, Mark. I'll keep looking. When I search for "Monarch" I find endless pictures of 10EE toolroom lathes...

But look what I just found:

http://www.machineco.com/Lathe_CNC_8...L_stkP0159.jpg

which is a little bigger than what I'm considering.

On the other hand, I guess it's not toally unknown to just bolt a lathe up sideways like Geoff said:

http://www.micksmisc.com/wp-content/...4/cnclathe.jpg

Best regards,

Randy

[Geof]

Obviously the box was already weakened . And 'far out' ideas turn out to be close in.

[CarbideBob]

Course you could turn you pictured late up on its end, Chuck facing up, mount the lengthwise axis on the in/out axis and then you'd have a VTL.
The reason for a slant bed design is to get the chips to fall to the bottom of the machine. This is the same reason horizontal mills are preferred for high production use over verticals.
Rear feeding tools are used so the machine won't be so deep and the operator can get closer to the chuck for loading.
Over the years lathes have been built in just about every orientation imaginable.
On a small lathe like this you've got lots of options so you might want to build a strange configuration just for the wow factor when you show it to others.
Bob

[gridley51]

Randy,you will struggle to find a pic of a DSG Monarch on the net.It`s well over ten years since I`ve saw one in the flesh and I doubt there are any left.
The Boxford you linked are quite common,I know a guy who has four larger versions of these,all needing retrofits.The Boxford software is another problem usually leading to a retrofit.
Mark.

[zephyr9900]

Mark, I just found this video and two others by the same guy:

http://www.youtube.com/watch?v=ck-JyqBouqM

He's using Mach3 to control his Boxford. Maybe your friend can talk to him. Mach3 is really nice software. My Tormach mill uses a customized version and I really like it (having used TurboCNC for several years on my Sherline mill)

Best regards,

Randy

[zephyr9900]

Originally Posted by CarbideBob On a small lathe like this you've got lots of options so you might want to build a strange configuration just for the wow factor when you show it to others.

Maybe I'll just mount my Sherline upside down. Most of the chips end up on the floor anyway...

What would really be wow would be finding a tiny power chuck to fit the Sherline spindle. Then I could crank out my model railroad wheel blanks by the dozen!

Best regards,

Randy