Interesting cold saw problem

No, I do not have a cold saw, but an acquaintaince of mine does. This
is a Dake cold saw. My own participation was making a base on casters for
this cold saw.
It has a coolant pump that is driven by the main motor shaft. The
problem was that the pump was not pumping.
The following observations were made.
0. This is a 3 phase saw.
1. Today was the first time the saw was started after ebay purchase
2. It was initially wired incorrectly so that the blade rotated
backwards (local wiring problem).
3. Despite that, there was healthy coolant flow.
4. The saw was rewired to rotate properly
5. The saw cuts well after reversing
6. There no cooland flow any more and the little pump does not pump
anything, maybe 1 cubic centimeter per minute or some other
ridiculously small amount
Any idea what could possibly be wrong?
Besides that, it was a day of fine 7018 welding and some fun
fabrication and algebra.
Reply to
Ignoramus6145
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I would check the coolant circuit from the pump intake to the outlet for an obstruction. Try removing the delivery hose and give it a quick burst to see if the pump is really at capacity. If it is, try rodding the delivery system out with a piece of welding rod or something like that. Sounds like there is some clogged up gunk in there.
Jim
Reply to
Jim Chandler
Was the blade on backwards initially?
--Winston
Reply to
Winston
I don't know how this particular pump is built - I've seen pumps with rubber impellers - the impeller touches the metal sides of the pump - it gets brittle with age - if it reverses the impeller can break into bits.
it's also interesting that you said it worked when the motor was running backwards - I think I'd think hard about that piece of info - are you sure it wasn't running the right way?
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Reply to
William Noble
What happens if you reverse the phases to go back to original condition?
Wes
Reply to
Wes
The pump is fine, your thinking is not. The pump is now going backwards. Swap the phases back the way it was and swap the blade around because you mounted it backwards. Additionally, the curtting circumference should be pulling the work into the fixed side of the holding vice for safety reasons. In other words AWAY from the operator! Steve
Reply to
Steve Lusardi
On Sat, 31 May 2008 22:53:54 -0500, with neither quill nor qualm, Ignoramus6145 quickly quoth:
Damn, Ig. Don't troll us. Rewire to original and reverse the blade so it cuts properly.
Reply to
Larry Jaques
The blade was not backwards. It has to rotate in a certain way so that it does not throw the chips at the operator. It is kind of a interesting idea, but I think that the blade should rotate so that the chips are removed away from the operator and not thrown at his face.
Reply to
Ignoramus31682
See my previous reply. I think that it was wired wrong (local 3 phase plug was wired wrong) and now it is wired right. But the pumps seems to disagree with that!
Your hypothesis about the impeller, however, sad, may be correct. However this guy thinks that it is a diaphragm driven pump, though no one is sure at this point.
Reply to
Ignoramus31682
That's exactly how it is wired now. The blade pulls the work in towards the fixed side of the vise. It was wired wrong and pushed work away from that side.
i
Reply to
Ignoramus31682
It does sound like something is screwed up. Dake still exists, so can probably be persuaded to provide a manual.
Joe Gwinn
Reply to
Joseph Gwinn
I wonder if the cold saw was made by the same Italian manufacturer than made my Wilton cold saw. If so the pump is a diaphragm pump on an eccentric so rotation direction does not matter. I am guessing a stuck check ball or some corruption in the line is the problem. I was told the pump is the same as a fuel pump on a Fiat car.....which one is another question. I bought a coolant pump and tank from Enco and forgot about all that monkey motion. Steve
Reply to
Up North
Check to make sure any check valves or foot valves are free and clear and pointed the right way, and the In and Out hoses of the pump are on the right nipples. And make sure the hoses are clear and not collapsing on the suction side.
The previous owner may have had a production reason to run the blade "backward" and throw the chips forward into a bin, and reversed the pump hoses to get proper coolant flow on opposite rotation. You put the rotation back the way it's supposed to be without reversing the prior owner's modifications.
After that, open the pump and check the impeller. If it was petrified rubber, running it backward and then forward might have been enough to rip the vanes off the impeller. Dumber things have happened.
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Reply to
Bruce L. Bergman
don't think there is any standardization for phase sequencing or rotation between different systems. So, how the previous owner had the saw wired has no bearing on how it will rotate when it is connected someplace else. As far as I have been able to learn, you always have to check rotation when connecting a 3 phase motor regardless of how it was previously connected. Of course if both motors are three phase one might rotate correctly and the other incorrectly if the internal machine wiring is incorrect.
Don Young
Reply to
Don Young
No issues were found along the above suggestions.
Maybe.
I think that the good approach would be to find the manual, read the manual, and give Dake a call.
Reply to
Ignoramus31682
Most of the cold saws I have seen have a diaphragm pump working off an eccentric spot on the blade drive shaft. They are notorious for clogging up with rubbish on the intake side or getting a little flake of swarf under th intake valve. They will pump happily independantly of the direction of rotation. . Take off the inlet line at the pump and blow a bit of compressed air through it. If that doesn't fix it, then blow the air through from the tank end of the hose. This may dislodge what ever is under the valve. The valves are usually removeable, so you may be able to unscrew the cap over the valve and clean it out. Careful, though, ther is a spring in there that will jump out and roll under your milling machine if it gets a chance. If that doesn't work, then panic.
Reply to
Grumpy
The phasing of three phase wiring isn't usually standardised. Most electicians just hook it up, start it up and if it runs backwards, just reverse any two of the three wires.
Reply to
Grumpy
And reversing the blade would make it cut IMPROPERLY.
Reply to
Ignoramus27711
What he is trying to say is that if the pump is 3 phase, swap two of the three wires feeding it. Do not swap the wires for the main motor.
Shawn
Reply to
Shawn
I think that the pump is mechanically driven by the motor shaft. That makes the story so very puzzling.
Reply to
Ignoramus27711

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