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Omal Hinge Borer Troubleshooting

Jeff S Member

I recently inherited an almost functional Omal Hinge Boring/Insertion Machine. I believe it is the "Easy Bore" model.
I've been using it at our cabinet shop for the past 10 years. It's been a solid workhorse.
The issue it is having is with the boring head not returning back up the cylinder. When the machine is turned on with air supply, you have to manually slide the head back up the piston (which is hard and heavy). When you depress the bore button, everything functions correctly except it stays at the bottom of it's path and keeps rotating the bits. Any help would be greatly appreciated. Thanks,

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2/5/21       #2: Omal Hinge Borer Troubleshooting ...
Oggie Member

I believe that green button controls pneumatic valve(s) for the main piston, as well as two small pneumatic clamps.

It could be an electrical button in which case valves controlled by it are most probably some solenoid controlled valves (i.e. they open or close with electrical signal).

It could also be just a push button of the pneumatic valve that is controlled mechanically by that button, and the rest of it is inside the control box.
I believe this is more likely than previous case.

Starting and stopping of the drilling motor is probably controlled by some electro-mechanical limit switches that get mechanically triggered by the head traveling up and down somewhere along the way.

Your pneumatic cylinder is double acting so the problem is with the air supply at the bottom side of it (that's why it's not going up). I would suggest opening that control box and see what's inside, or try to peak from underneath it.
Just follow the air hose from the bottom of the cylinder backwards to the control box and see what gives it its air.
The cheapest try would be to replace that thing first and see if it helps (I assume you don't hear any air leaks at this time and some hose is not pinched somewhere so that air can not flow through).

If possible try to read the name of the part, find out what it is and than find locally available equivalent replacement. Save yourself money and time by not trying to find the original part.
Local rep from was extremely helpful in my case.

2/5/21       #3: Omal Hinge Borer Troubleshooting ...
Oggie Member

"I believe that green button controls pneumatic valve(s) for the main piston, as well as two small pneumatic clamps."

Not the two small pneumatic clamps. That's the black switch bellow :) Sorry.

2/6/21       #5: Omal Hinge Borer Troubleshooting ...
Jeff S Member

Thanks for your help.
I noticed one other important thing that the machine is doing. When air is hooked up to it, there is a constant flow through the "clean out" hose. The hose I'm referring to is right over the boring head and it's function is to blow away the shavings created by boring.
I know this machine (when functioning) only would put out a stream of air from that "clean out" hose momentarily during the boring process.

I am with you on thinking this is an air flow/valve problem, I will follow the air lines as you suggested.

For further explanation, here is how the machine is supposed to work. There is a switch you turn 90 degrees to engage pneumatic hold clamps (that works).
Then you depress and hold down the green bore button until the boring is complete. Upon release, the boring head travels back up and I believe that's when it shot the stream of "clean up air".

I'll post if I find anything out.

2/6/21       #6: Omal Hinge Borer Troubleshooting ...
Oggie Member

If there's a constant flow of air through the clean-out hose than most probably that is where the machine is loosing pressure and there simply may not be enough of it to pump the piston up.
In that case check that thing first before anything else.
If you can, close that hose somehow and see if the rest of the machine works as it should without it.

2/6/21       #7: Omal Hinge Borer Troubleshooting ...
Tom Gardiner

Sticky valves is my guess. Have you ever added air tool lubricant to the air supply? How clean is the regulator filter? Try plenty of drops of oil in the supply line and numerous cycles to free up the mechanism. Next step is disassembling the works for a deep cleaning and checking the seals.

2/6/21       #8: Omal Hinge Borer Troubleshooting ...
Jeff S Member

Thanks Oggie and Tom for your time and responses. I will try everything you all suggested and let you know how it turns out.

To answer you Tom, likely was not maintained with oil.

2/8/21       #9: Omal Hinge Borer Troubleshooting ...
Jeff S Member

Tried multiple cycles of oil and it didn't change it's behavior.
I opened up the control panel and had a look. The green bore button goes to a mechanical valve which has multiple air lines running to it. See photos for part.

Is it likely enough that this has failed and that it warrants buying a new one and swapping it out? Depending on where I purchase, it's around a $40-$50 part. Would I be better off doing some further diagnostic before I begin throwing money at it?

I have never worked on pneumatic tools like this and don't have an understanding of how they operate. Once again - appreciate the help!

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2/8/21       #10: Omal Hinge Borer Troubleshooting ...
Oggie Member

It depends how much you value your time.
I would not blink over $50 if it could save me few hours or bring my machine "online" today instead of, like, next week.
The loss in time (and time = money) caused by machine not working or me fiddling with it instead of building and installing cabinets is ridiculously disproportional to that part's cost.
However, if you have some spare time or want to learn more about your machinery (which is always a good thing), then why not.

Replacing that part is straight-forward operation. Those are quick connectors (just push-in to connect the hose, and depress the ring and pull-out to disconnect it), and everything should go very easy. Just make sure you buy new ports (those things that accept that black air-hose); they need to have the right thread size that will fit into your new part and have to accept exactly that diameter of your black air-hose).

I'm not expert on pneumatics, but it looks like every major industrial country has it own standards regarding the threads used in pneumatic/hydraulic industry.
I think if you send that photo to and measure the diameters of those black air-hoses someone will give you exact part numbers that will fit with each other.

Or, if there's some pneumatic supply shop in your area it may be even faster.

2/8/21       #11: Omal Hinge Borer Troubleshooting ...
Dennis Bean  Member


Hey Jeff,

There are a few possibilities;

The seals in the cylinder are the most likely cause.

The green push button valve may not be functioning properly. It is simply a pneumatic valve to route the air pressure to the top or bottom cylinder chambers.

The guide bearings on the posts may be gummed up with dust, debris, rust, etc., but that is highly unlikely


2/12/21       #12: Omal Hinge Borer Troubleshooting ...
Jeff S Member

I swapped out the pneumatic valve behind the green push button and am still having the same problem.
Are the seals in the cylinder something I can purchase and replace? There are no markings on the outside of the cylinder.
The only other component I see in the chain is another small valve (directional valve I think). Attached photo. I'm leaning towards the cylinder seals.
Appreciate any other thoughts or info on sourcing seals.

View higher quality, full size image (2016 X 1512)

2/12/21       #13: Omal Hinge Borer Troubleshooting ...
Oggie Member

I'm suspicious about the seals being the problem, because there would probably be some problems with going down operation and drilling too since it's the same piston that goes up and down.

However, it should not be a problem to open the cylinder.
First detach the piston from the drilling head then just unscrew the round tube from the square aluminum base. Make sure to support the drilling head with something when doing that, because it will fell down otherwise. Also, be very careful with unscrewing and screwing back the cylinder since those will be some fine threads in aluminum and it is very easy to ruin those since aluminum is soft and if you start screwing the cylinder while it's not exactly perpendicular to the base you may ruin those treads before you notice that something is wrong. In other words, don't use too much force when screwing it back, it should go easily if you align the threads correctly. Start tightening only when you're sure everything is aligned.

If I was in your place I would check if that valve at the bottom gets correct control signals.
Most likely that is some directional valve controlled with "pilot signal". In this case the controlling signal is pressured air that comes through (most probably) that black hose connected at the top side of the valve.
So, it's either that valve is no good or it does not get good pilot signal, then trace back that signal and see what supplies it.

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