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SCMI 24" WIN CS 63 Widebelt Tracking - Pneumatic to Electric Eye Conversion8/1/20
I have a new-to-me 24" Win CS 63 SCMI Widebelt sander. The machine had some electrical control circuit issues when I first brought it into my shop so it wasn't running. I was able to remedy that with some assistance from a few friends, an SCMI tech and a significant amount of wire tracing. Once I got the machine to power on, the pneumatic tracking system was having issues. There are a number of parts that are made of plastic and they had either deteriorated or been broken and repaired by the previous owner with copious amounts of epoxy. I got spare parts from SCMI and now the machine is operational. Yay! That being said....
The machine uses quite a bit of air while running and I'm hoping to make it much more efficient on usage. I have an older Kellogg American 2hp air compressor with maybe a 40-50 gallon tank and I'd prefer not to move to another compressor as this is a good unit and has always worked fine for me. It also doesn't dim the lights when it comes on which is great! I have a buddy (Peter) who suggested converting the pneumatic tracking system over to an electric eye. My understanding is that older machines and also less expensive machines tend to use pneumatic tracking while newer, nicer machines go with the electric eyes.
He said I should only need three parts to make the changeover which are all readily available from McMaster Carr -
Photoelectric Swith with Relay Output (9231K22),
Peter's machine has two pistons that control the back/forth motion of the idler. My sander has a spring return and only one pneumatic piston. I'm happy to post as many pictures of my machine as would be helpful. Hopefully this can serve as a starting off point for someone else in the future as well.
Here's the current pneumatic piston setup on my machine. The blue arrow points to the OEM SCMI pneumatic tracking components (spoon and spoon holder). The yellow arrow points to the pneumatic cylinder which does the steering based on feedback.
I'm hoping for two things from you fine ladies/gents -
1. To obtain a more concrete understanding of how this photoelectric switch and solenoid "talk" to each other and indeed how they get integrated into my 240v machine. I don't have a 120v transformer anywhere in my control circuitry so I will need to either add one (or a 24vdc transformer). I'm putting a 48vdc transformer into the cabinet to control a stepper motor for the up/down motion of the table but unfortunately it doesn't look like they make the solenoids for 48vdc. I can no doubt get a 24vdc one cheap on eBay though and they are tiny so if that would work just as well as 120vac I guess I'd probably opt for that.
2. To determine EXACTLY which solenoid valve I will need. Peter needed one with 5 ports, but he's thinking maybe I only need one with 3 ports. Again, since I've never had any experience with solenoids, electric eye tracking systems on sanders, etc I'm hoping to tap into the vast array of knowledge that's no doubt represented on this forum. Any help is greatly appreciated.
I realize to some that it might seem like too much work for this size machine, but my workshop is small and this is literally the largest machine I can fit into my space. I think it will work well for my needs and my hope is to make it as nice as possible within reason. I plan on keeping it for the foreseeable future.
Before you go to all that trouble, I'd take a much closer look for air leaks. A cracked air line, a loose fitting, or that janky connection shown in your photo could be causing your excess air consumption. Pneumatic tracking shouldn't use that much air.
I did this same conversion on a large double belt sander many years ago (Mid 80's). It was definitely worth doing.