deserthound
spending too much on rocks
Member since December 2013
Posts: 390
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Post by deserthound on Jul 4, 2014 20:38:43 GMT -5
I have read alot of articles lately on slab saw. speeds of this and that and all kinds of rpm's sfpm, and on and on...so of course now i'm more confused than ever ..hope i can make this short..lol..saw in question..16" covington combo..problem rock jamming and excessive clutch slippage..answer:feed speed to fast. right ? ok..i cant slow the feed speed down that i know of it has its own lil motor and is set at 12" per hour..so no way to change that besides changing that gear reduction motor. Ok.the saw in question is less than 5 yrs old, it came with a continous diamond blade 2" pulley on the motor 3" on the arbor giving me approx. 1100 blade rpm and the 12" feedspeed.... the arbor went bad, the lil gear reduction motor went bad within a year. after about 25 cut and jamming and clutch slipping i bought the MK303, ..no real change...ok what i did learn that the continous blade will go 1100 while the slotted Mk should be 800..so i was a bit fast with the new blade..now to get the 800 or so i go with a 2" motor pulley and a 4" arbor pulley and of course 16" blade getting a blade rpm of 805...but still having 12"per hour. i really dont see how this will help with jamming when i just changed blade speed not feed...what am i missing...what would be the recommended cutting speed for an agate in inches per hours i think i read 5" somewhere dont remember, mine is 12 no matter what speed everything else s going. any help is greatly appreciated.
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Post by phil on Jul 4, 2014 21:04:35 GMT -5
Contact Steve at Covington and have him explain how to adjust the clutch so it slips like it's supposed to. Also ask the correct blade and feed speed for that system. If it's out of balance it can cause all sorts of problems.
Slippage could also be dull saw blade, making the autofeed overdrive the blade cutting ability. Jamming could be dull blade, or rock moving in vise, vise worn and doesn't stay straight, etc. When you slow down the blade, you're slowing how fast the blade cuts thru the rock, NOT how fast or slow the autofeed runs. Better to have blade cut (go) faster than the feed can feed the rock into it than vice versa, if you're overdriving the blade, it can cause jams, dishing, excessive blade wear (dulling), blade overheating and losing diamonds, etc. How often do you dress your blade? Did you take the time to align the new arbor properly? If it's the least bit off, you will jam everytime. Sounds like you need to revisit the alignment. It's unusual for both arbor and feed motor to go in a years time, you should have been under warranty? Regardless, I've always found Steve to bend over backwards to help and explain things on the phone. He's the main saw man there. Oldtimer too. I'd call and enlist their help.
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Post by Rockoonz on Jul 4, 2014 21:24:54 GMT -5
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deserthound
spending too much on rocks
Member since December 2013
Posts: 390
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Post by deserthound on Jul 4, 2014 21:33:13 GMT -5
thanks Phil for all the info. i have sent emails but maybe i will call instead... i keep the oil clean and use a good grade mineral oil i sharpen the blade with a silcone oxide block..i try and follow all recommendations. most of what you mentioned i have checked and rechecked and am thinking i will rebuild from ground up this time..and yes the lil motor was replaced no charge, the arbor was a few months over warrent so i paid..but this is not about all that..
you said : better for the blade to cut faster than the fed can feed, what my problem is overdriving the blade, so i need to slow down the feed speed...if i increase the blade speed its beyond mfg recom. of 805 blade rpm for the blade..i am trying to get in my head what i will ask Steven and not get all confused..
i would still like to know what is recommended for cutting a hard rock in inches per hour.. i really think its all in the feed speed but dont know how to change it, really dont understand why i should have to
and last but no least if this is a losing battle with this machine please let me know, i need a reason for a 20" anyways..
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Post by phil on Jul 4, 2014 21:43:53 GMT -5
you said : better for the blade to cut faster than the fed can feed, what my problem is overdriving the blade, so i need to slow down the feed speed...if i increase the blade speed its beyond mfg recom. of 805 blade rpm for the blade..i am trying to get in my head what i will ask Steven and not get all confused.. I think you've got it backwards for those saws. The feed speed is fixed. Only thing you can adjust on the feed is the blades "clutch". So no, you don't need a slower feed, you need a faster blade speed which will make it cut faster than the feed shoves the rock into the blade... The "manuf's" recommended speed was for the blade that came with it, NOT the saw. the unit can handle the increased speed. You ALWAYS want to follow the BLADE manufacturer's blade speed recommendations, that's what matters. i would still like to know what is recommended for cutting a hard rock in inches per hour.. i really think its all in the feed speed but dont know how to change it, really dont understand why i should have to Nope, you don't have to change the feed speed! feed speed is different for different manufacturers saws, design ,etc. As Rockoonz said you can run the blade way faster than you have been. You're adjusting things the wrong way and making things worse. Speed up that blade!and last but no least if this is a losing battle with this machine please let me know, i need a reason for a 20" anyways.. Not a losing battle at all, you just need to reverse your thinking.
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deserthound
spending too much on rocks
Member since December 2013
Posts: 390
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Post by deserthound on Jul 4, 2014 22:00:00 GMT -5
wow the light went on..i got it..yeah i am azzbackwards sometimes..lol..thanks you guys ..it may have been that red lettering that did it
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