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Flexible, powerful benchtop machining setup using a baseplate

jscpm

Titanium
Joined
May 4, 2010
Location
Cambridge, MA
I thought the readers here might be interested in seeing a machining setup I constructed recently using a heavy duty optical baseplate. This kind of setup allows me to get a very good power to size ratio. In the configuration shown in the photo below we are grinding a precision bevel on die. Sure, you can do this with a big $30,000 surface grinder, but here I am accomplishing the same thing on a bench using equipment costing less than $3,000. Also, it is being done just using standard 120V power. This setup is flexible because we can reconfigure it to act as a lathe or as a horizontal milling machine all in the same small footprint. The bench or table used must be VERY strong and stable. In our setup we use heavy hardwood 2" tops with 6x 6" oak pedestals.

The key is the motor. We are using a Baldor CEM 3456, which is a true 3-phase, four pole 1 HP motor. This gives a lot of torque even at low RPMs. We get variable speed control by using a Leeson Speedmaster SM2 type 174605 motor controller. This both converts single phase 120V power to 3-phase 230V for the motor, and gives us the ability to control the RPMs.

The frame of the setup is constructed with thick walled aluminum cylinders and 5/8" aluminum plate, all precision machined for flatness. Everything is bolted to the base plate. Note that it is a "soft foot" motor, so a shim kit is needed to align the motor. Also, the arbor must be carefully aligned with the motor shaft, which requires a skilled process described in mechanical textbooks. The arbor bearing is provided by a simple babbit bearing and oil flask. Felt washers are clipped on to prevent oil from seeping out. For the grinding wheel arrangement we had to machine a custom arbor. Trying to find a commercially available arbor that fits what you are doing is a lost cause, so just plan on machining the arbors you need.

To position the work, here we are using a combination of small linear motion ball screw guide and a scissors Z-stage of the type used in optical work. This Z-stage allows us to control the up-down motion of the work very precisely.

To dress the wheel you can see we use an angle adjustable magnetic chuck. Obviously when using a grinding wheel you need to have a guard, here supplied by 3/8" plexiglass.

base-plate-system_view.JPG
base-plate-system_stage.JPG
 
I’m applauding the creativity while simultaneously crying at the thought of that very nice little positioner being bathed in grinding dust. I’ll have to keep my eyes open for a nice little baseplate like that. I’ll never look at the ThorLabs catalog the same way again.
 
Not cheap, but readily available:


And they have a line of other optical-mechanical devices, also not cheap:


It should be easy to cover things in a set-up like this to shield against grinding dust. Aluminum foil can be your friend here. You can even put it between precision elements because it has a very uniform thickness.



I’m applauding the creativity while simultaneously crying at the thought of that very nice little positioner being bathed in grinding dust. I’ll have to keep my eyes open for a nice little baseplate like that. I’ll never look at the ThorLabs catalog the same way again.
 
That is a very nice composite core table. The one above looks like a plain aluminum one. That can be had from Thor for $550 or $750 for a 2’ square either 0”5” or .75” thick.

 
"Powerfull" ???
It's all relative; 1hp in that footprint is powerful. Horses for courses.

32acb52b9e.jpg

And as some here have operated powerful surface grinders, there are those which make this one look small.

jack vines
 
It's all relative; 1hp in that footprint is powerful. Horses for courses.

32acb52b9e.jpg

And as some here have operated powerful surface grinders, there are those which make this one look small.

jack vines
'while I have run that machine ^^ you posted a pix of, the OP's 1 hp with those ways & no mass to speak of underneath it all is wasted HP.
 








 
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