Need Application Advice

[slevy]

I am a stone fabricator and am trying to make an automatic linear cutting saw. What I have so far is a worm drive circular saw mounted on an aluminum base which slides upon a extruded aluminum track. The track is 30 inches in length. My desire is to propel the base along the track to the end, reverse the travel back to the starting point and cut all power to the saw and drive until the operator starts the process again. Additionally, I need to be able to control the speed of travel.

From what I have been able to glean from the web, it seems I can either use some kind of threaded rod or somehow mount a motor to the saw with a wheel that is in contact with the track.

Any help to get me started would be greatly appreciated.

Thanks

[Evodyne]

Originally Posted by slevy I am a stone fabricator and am trying to make an automatic linear cutting saw. What I have so far is a worm drive circular saw mounted on an aluminum base which slides upon a extruded aluminum track. The track is 30 inches in length. My desire is to propel the base along the track to the end, reverse the travel back to the starting point and cut all power to the saw and drive until the operator starts the process again. Additionally, I need to be able to control the speed of travel.

Slevy,

Hi! How simple do you want to go and what is your budget? And how are you with understanding electrical schematics? The only way I know to convey the information is via a schematic drawings.

You can do a lot of what you want with a few electrical relays, some limit switches, and some pushbuttons. The right combination of these parts will handle the out and back and powering down part and will be very reliable

The "other" part is the speed control for the saw movement. I assume you want to control the cutting speed, but have a fast retract speed to boost production. Remember you need enough "oomph" to push the saw through the stone. A smallish DC motor will be too fast and not have much power. By reducing it's speed via belts you will get the rpm you need and also boost the torque. The most basic speed control can use fixed resistors to give fixed speeds. You would select speed A, B, or C... A relay can reverse direction. Big power resistors get hot, can be expensive, and limit you to only certain speeds. Cheap motors can be 12V electric window motors from an old car.

The next step up would be to use a small variable speed board. A potentiometer with a knob would set the speed. It would be infinitey variable. These can be purchased with a control for direction, so making it reverse is not to difficult. The drive has to be able to handle the current that the motor will draw when loaded down.

Why not write back and let us know your complexity/budget constraints. We can go from there...

Evodyne