SCMI 24" WIN CS 63 Widebelt Tracking - Pneumatic to Electric Eye Conversion

[Matthew McMillan]

Hello,

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),
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Bicycle Reflector (9231K31)
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and a solenoid. Peter has a Powermatic machine and had to replace several non-functioning parts on it. He ended up using an Air Directional Control Valve Electrical Solenoid (6124K512).
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I'm not sure if I will need the same valve or a different one.

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.

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Here's the current pneumatic piston setup on my machine. I have no idea why the picture orientation is messed up when I post them?
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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.


Thanks!
Matt

[Steve Jenkins]

My only comment on electric eye tracking is if your dust collection is marginal make sure you keep the eye wiped free of dust. I made several service calls for no tracking and all I did to fix it was wipe off the eye. Thanks

[Matthew McMillan]

Hi Steve,

Thanks for your message. I have a 7.5hp Torit cyclone. I assume that's enough to handle things, but I have heard the same thing you're saying.

[Stan Coryell]

I don't know anything about your sander.
Why is it using so much air?
What's the thing before the piston? A valve of some kind? It looks mangled.
3 port valves are for single acting non vented pistons.
5 port are for double acting non vented pistons.
If the piston is double acting, but with no air to return it (a spring instead) you need 3 port. This assumes the 2nd port on the piston is vented to atmosphere.

[Ron Selzer]

following as want to do the same

[Stan Coryell]

following as want to do the same

Why? How does it work now? Is it unsatisfactory?

[Ron Selzer]

Why? How does it work now? Is it unsatisfactory?

Air usage is higher than I like.
Have to run the two stage compressor to supply enough air with some downtime for the compressor.
Pancake compressor will run it, however never shuts off.
If there is a viable solution for $100 not using air then I am interested as the price goes up I lose interest.
There is a constant air bleed/usage whether the sander is running or not.So shut the air off when not using the sander, ok when batching wood thru it. Pain when wanting to sand one's and two's. Forget to turn the air on and ruin a belt, leave the air on and compressor runs just as much as if the sander was running all the time.
Ron

[Matthew McMillan]

I'm not sure if the air consumption is just really high on this particular model or if my machine has some extra leak(s) somewhere. I can tell you that when I have just air pressure to tension the belt it's not using much. Then, when I allow air to go to the tracking system it starts using lots of it.

What's the thing before the piston? A valve of some kind? It looks mangled.

I think you're talking about the spoon/spoon holder. That's what controls the pneumatic tracking. The spoon holder was previously repaired and has a bunch of epoxy on it. I have since replaced that so now it's a new plastic piece that doesn't have any extra holes in it.

I'm not sure whether my piston is vented or not? I'm assuming it is. It is only a single action and has a spring to return it.

[Matthew McMillan]

This is my problem too. The machine is running and tracking properly, but my compressor doesn't stop running once it starts. I just don't see it as a viable long-term option without timing myself for only 5-10min of sanding per session. It would be nice if I could use my same compressor but have the sander using less air.

I figure it has to be possible since the pneumatic tension of the belt would be high pressure but low usage even with a vent on the piston. And then the pneumatic tracking would have to be substantially less if it were optical instead of adding essentially two more vents to the system.

My buddy Peter said he runs his electric eye machine with a small compressor and it's also a 24", though it is a Powermatic.

[Stan Coryell]

Like I said, I don't know anything about belt sanders. I'm not sure how the photo eye solves the air consumption issue
I'd make sure there aren't any air leaks. I'd guess that air cylinder is passing air.
It looks like there is a solenoid after the regulator and before the spoon. What does that do?
What do you have for motor controls?
Do you have a schematic?

[Bobby Robbinett]

I have had both styles of wide belt sanders, one electronic and one pneumatic. My current sander is a 25” Cantec that is only two years old. It uses pneumatic I believe (haven’t got it set up yet) and the sander that it replaced was pneumatic as well. As a matter of fact I might attempt to convent my old sander to electronic tracking before I sell it just to practice on a sander before I go modifying my new sander. Years ago I worked in a shop with a big 51” or so sander with electronic tracking. It used very little air.

I was told by a tech with one of the big industrial manufactures that you will spend $800 to $1,200 changing them over. I have been considering this even before this thread was posted. I just get lost when the electrical part of this comes up.

[Matthew McMillan]

That solenoid is an emergency brake. I can't remember what sets it off, but it has an air line that goes down to the main motor. A simple trip of one of the safety switches doesn't seem to activate the emergency brake.

The pneumatic tracking involves a constant stream of air getting blown at/around the belt. The optical version doesn't use any air until the belt needs to be steered back to center. My understanding is this would be a constant back/forth motion with the belt but still the optical version would be way more conservative with air usage.

I have a schematic for the control circuit but it doesn't show anything with the pneumatic system.

[Matthew McMillan]

Peter told me it costs about $300 to move over to an optical setup. I'm hoping someone who has done this might see the thread and could give some guidance. That's using parts off the shelf from McMaster Carr.

There's another thread that I found where some people are talking about it. David Kumm seems to know about this but I haven't figured out how to send him a direct message. Fingers crossed he sees this thread!

[Ron Selzer]

Like I said, I don't know anything about belt sanders. I'm not sure how the photo eye solves the air consumption issue
I'd make sure there aren't any air leaks. I'd guess that air cylinder is passing air.
It looks like there is a solenoid after the regulator and before the spoon. What does that do?
What do you have for motor controls?
Do you have a schematic?

On mine you can hear air blowing all the time
When changing belts I insert the belt until I hear the air flow change at which time the top head angles. Pull the belt back a touch and it will angle the other way and air flow sound changes back. At this time it is close enough to use. When it starts up the belt will start tracking with the control moving the head a little bit as needed. If the belt goes too far either way than there is a finger on a limit switch that shuts the machine down. Sometimes a belt gets to where it will constantly run of to one side, I then remove the belt and turn it 180 and insert it back in. Seems to fix that problem. Have a schematic somewhere that lists the airflow requirements. Would be nice to use a smaller compressor to tension the belt and only run when needed for changing belts.
Ron

[Stan Coryell]

I need more information. Can you show/explain how the pneumatic tracking works. What reads the air stream and triggers the piston. 1 sensor or 2?
I guess you want to replace them with a photo eye. What do you have for control voltage?