Pump problem on horizontal band saw

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gangel99
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Pump problem on horizontal band saw

Post by gangel99 » Thu May 26, 2016 1:29 pm

I have an old Jet 7 x 13 horizontal band saw, bought used years ago, that has been a great boon to my work. When I bought it the 'coolant tank' was a plastic bucket with a pump in it and some stainless mesh duct taped over the top of bucket as a strainer. Recently a friend was using it and accidently dumped all the coolant out. This was several weeks ago and today I replaced it with new coolant, put the pump in, turned it on and it sounds normal, however no coolant gets to the saw blade.

I downloaded the manual for the current model and the pump setup is simply pouring coolant into the tank. Any ideas on further troubleshooting?

Thank you,

Vakil

KMoffett
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Re: Pump problem on horizontal band saw

Post by KMoffett » Thu May 26, 2016 3:18 pm

I have one of those saws. Can you post a photo or two of the setup. There should be a hose connecting the pump to a nozzle near the blade. Did you take the mesh off to look in the bucket?

Ken

spro
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Re: Pump problem on horizontal band saw

Post by spro » Thu May 26, 2016 4:38 pm

The pump has lost its "prime". The narrow aperture at the exit is a restriction to the input. You may remove/clean it. By some means you feed into the input and while primed, it will stutter and be primed. It will then pump as before.

gangel99
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Re: Pump problem on horizontal band saw

Post by gangel99 » Thu May 26, 2016 5:11 pm

Attached are three pics. The first one ('Saw') is a pic of the saw (a bit out of focus) where the yellow arrow points to a red toggle that controls the coolant flow. It is in the off position.
Saw.jpg
The next one shows the other side of the saw and the coolant bucket - i removed the stainless mesh.
Saw & Coolant bucket.jpg
The last one shows the pump outside the bucket. The Yellow arrow points to the hose connection at the pump.
Coolant pump.jpg
I was thinking of unfastening the hose at the pump and if it pumped then I could assume the problem is not with the pump. OTOH it would introduce air in the line which might make it worse.

Thanks for your comments.

spro
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Re: Pump problem on horizontal band saw

Post by spro » Thu May 26, 2016 6:04 pm

Edit: The pump would have to be in the media or you can't check pressure. Often there is a valve, a worn gland or seal on the intake which is not apparent until the pump is replaced and cannot achieve the same priming as before. Every vacuum leak which existed before the small network was disturbed, is magnified.

Harold_V
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Re: Pump problem on horizontal band saw

Post by Harold_V » Fri May 27, 2016 1:14 am

One thing to consider is that the pump may not be running, although it may be humming as if it was. Old coolant may have dried in the bearing, causing it to bind.

Lift the pump out and turn it on to see if the motor shaft spins.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

gangel99
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Re: Pump problem on horizontal band saw

Post by gangel99 » Tue May 31, 2016 5:38 pm

I took the bottom of the pump off to see if the rotor turned (it did) and anything was clogged. The picture shows it upside down with the cover removed. You probably know how it works - the coolant enters through a hole in the center of the cover (Right arrow) and the rotors push it up through the tube (Left arrow)
Pump bottom.jpg
So the rotor turns, nothing visible is clogging anything. I am not sure how to prime this pump. I'm going to try to fill it with coolant from the outlet side while it sitting in coolant at the bottom, and try tome suction if I can find something to fit a turkey baster or a squeeze bottle.

Definitely open to better ideas :lol:

spro
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Re: Pump problem on horizontal band saw

Post by spro » Tue May 31, 2016 6:11 pm

Investigate the impeller while here. There may be a lost blade or buildup underneath. The screw is likely stainless and may have a LH thread. Sometimes there is another port under the impeller which you can't see unless its cleaned out. Sure you're going to clean it and the gasket is terrible now but if there is an overload/regulation valve port under the impeller, it could be stuck open.

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warmstrong1955
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Re: Pump problem on horizontal band saw

Post by warmstrong1955 » Tue May 31, 2016 6:28 pm

Yes....a regular little centrifugal...that I have fixed and replaced a kazillion of.
Make sure the impeller isn't clogged, as well as the outlet housing. Impeller flow goes from the center out.
Make sure the pump is turning, (someone said that) and in the correct direction, and the impeller is actually turning. (I'm had pump motors get confused, and run backwards....they're cheap)
Remove the hose, and make sure the hose isn't clogged.
Be sure to submerge the pump above the shaft level, where it enters the pump housing, put the end of the hose in the sump or a bucket, or aim it someone you don't like.... & try it.

Those pumps don't make a lot of pressure.
If you have a clog, or clogs, or too much restriction past where the hose attaches to the saw, it may not be able to force the air out.
Make sure all is open & clear to the nozzle(s) on the saw.

Bill
Today's solutions are tomorrow's problems.

gangel99
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Re: Pump problem on horizontal band saw

Post by gangel99 » Wed Jun 01, 2016 12:39 pm

A BIG thank you to all - the pump (and saw) is back in action. Now I can get back to planning the cuts.

Apart from the engineering and the manufacturing processes to make the rotor this turned out to be a very simple machine. There was nothing fancy. The water goes in the center hole, the plastic vanes turn and force it into the hollow cast part that sends it into the rubber hose. There are no other valves or places where metal particles can clog it. When I took it apart there was nothing wrong with the pump but I did clean it FWIW :D

After rigging up a way to pour water through the hose (did not work) the culprit turned out to be one of the metal J parts that hold the rubber hose as it goes through the hose. It had gotten mashed a tiny bit which was enough to cut off the coolant supply.

Two lessons for me. The first is to be more confident about taking things apart. The second reinforces a lesson I should have learned awhile ago - do a thorough visual inspection before you do anything else. Of course if I had learned this lesson well I might never have taken it apart.

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mcostello
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Re: Pump problem on horizontal band saw

Post by mcostello » Wed Jun 01, 2016 9:01 pm

If You get too over confident We will be here for THOSE type questions also. :)

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warmstrong1955
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Re: Pump problem on horizontal band saw

Post by warmstrong1955 » Thu Jun 02, 2016 11:28 am

There ya go Vakil!

The problem is always in the last place you look!

:)
Bill
Today's solutions are tomorrow's problems.

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