DIY Space-Frame, Slant-bed Lathe

[Toymaker]

Shortly after moving to Thailand from the USA I spent a few months looking for a lathe but didn't find what I was looking for, so I decided to build from scratch a lathe with a rather unique design. While researching CNC lathes on the internet I stumbled upon a design I really liked; In place of heavy castings was a framework of steel tubes welded together. All the moving parts of the lathe,... bed, cross-slide, head and tail stock, were all mounted inside a steel frame; this looked incredibly strong and ridged.
Below is an early photo of my lathe.

Specs:

• 14" Max turned diam. over bed rails
• 10" max diam. over Z axis carriage
• Z axis travel: 35.5" @ 136 inches/min max
• X axis travel: 8" @ 204 inches/min max
• Overall dimensions w/o table: 142.4cm L x 55cm H x 74cm Deep
• Spindle RPM max 1600 with 2.5HP DC Motor
• Coolant system

Below is a photo of the frame sitting on it's bench in the welding shop.

One of the unique features of this design is the adjustable bed (the green frame) which sits on screw jacks which allow for pitch, roll, and yaw adjustment. Once the bed is in alignment, it's bolted securely to the frame.

The traditional headstock is replaced by a framework of steel plate and tubes welded together.

A 2.5 HP treadmill motor & speed control power the spindle. Step motor for the Z axis is mounted behind a steel plate to keep it clean and shielded from chips.

 

[Toymaker]

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[Toymaker]

I've tried to upload a video, but perhaps I don't have permission.

 

[rafe03 G]

That's an amazing piece of machinery you're building there.! What a chip maker!
Any advantage to filling the steel tubing w cement mortar (or other) to dampen harmonics n vibration? Some steel structures ring like a big tuning fork.? Chatter maker.?
While cast iron is naturally dampening (oh really?) steel less so (I think.).
Perhaps the sound deadening "stick-on" mat used by the Hot Rod Mob.
Keep us posted please.

Gus

 

[Toymaker]

That's an amazing piece of machinery you're building there.! What a chip maker!
Any advantage to filling the steel tubing w cement mortar (or other) to dampen harmonics n vibration? Some steel structures ring like a big tuning fork.? Chatter maker.?
While cast iron is naturally dampening (oh really?) steel less so (I think.).
Perhaps the sound deadening "stick-on" mat used by the Hot Rod Mob.
Keep us posted please.

Gus

I appreciate your concerns and suggestions and during the design and build phase, I posted a build-log on the CNC Zone forum where I had several DIY builders express their concerns about the likelihood of my frame ringing. However, in the 10 years I've been using my lathe, cutting brass, 6061 aluminum, 4041 Chromoly steel, or 304 stainless steel, I've had no problems with the frame ringing or vibrating. Even if I strike the frame with a hammer in an attempt to make it ring, it doesn't.

I did take precautions against ringing by using 303 aluminum sheet to cover the entire bed, that sheet is sandwiched between the linear bearing rails and the steel frame; this was done to dampen vibrations generated by the cutting tools.

Below is a short video (8 seconds) of the lathe cutting 304 stainless. You can hear a very short "chirp" or squeal from the boring bar at the moment the bar is pulled out, but that noise doesn't transmit into the frame.