spokanetim
has rocks in the head
Member since October 2009
Posts: 656
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Post by spokanetim on Jan 24, 2011 2:38:26 GMT -5
Hello to you saw experts, I need some help. I bought a very old and beat up rock 14" chop rock slab saw, should have taken a picture of what it looked like before. I used to have a run down 3/4 hp motor and a broken submersible pump for the oil coolant. I tore it down, had it sand blasted and then powder coated to make it new again. I replaced most the hardware (bolts etc) put on a new 1/2 hp motor, new blade and converted it from a oil saw to a water saw. I redid the coolant feed so its attached to an adjustable vaulve from my hose feeding as much water as I want to both sides of the blade. It's a beautiful setup if I do say so myself. I turn it on and it runs straight and true purring like a kitten. I also attached a tension spring to help in pulling the saw into the stone, needed at the start as it's fairly well balanced. So, with the new blade its first cut into agate was great. Second cut slower but not bad. Third cut and every cut since it cuts good for the first inch then it just stops cutting. It just spins and spins and cuts nothing, no matter how much force I put on the blade! I've added weights, manually pushed fairly hard and it still spins. Sure with the extra weight it cuts a tiny bit more but no where near what it should. If I push really hard (way more force than I would use on a tile saw blade) it will stall out the motor. Even with obsidian! What am I missing here? Blade is spinning good, at the right speed, plenty of downward pressure, blade is cold cause I can flood the blade with water, and it doesn't cut with basically a brand new blade. I've attached a bunch of pictures so you can see what I've done. Any idea's would be greatly appreciated as I've sank about $500 into what I thought would be a perfect saw for my needs. thanks for any advice, Tim
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Post by texaswoodie on Jan 24, 2011 7:26:00 GMT -5
Tim The only thing I can think of is you apllied to much pressure on the first few cuts and dulled the blade. Try cutting a piece of obsidian and see if that will help.
Curt
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Post by rockmanken on Jan 24, 2011 7:44:55 GMT -5
I have 2 of them. WILL NOT cut with water. Went back to oil and it is OK. Also, won't cut with mineral oil with a sump pump. Won't lift it up. changed pump to Lil' Giant and it pumps now, but oil goes everywhere, had to make side shields out of plexiglass. Ken
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Post by johnjsgems on Jan 24, 2011 9:05:37 GMT -5
Use a dressing stick, fire brick, fake cement brick, etc. to dress the blade. More pressure as blade dulls makes it worse. I had a home made 14" drop saw I used with Covington's green water soluble coolant and it worked OK. Ken is right though, oil works better for blades that large. Look at the latest Covington catalog and you will see every saw they make over 10" now comes with an MK blade (they are relabeling them but same picture,etc. as the MK blades listed in last year's catalog). Tells me either the Gold blade didn't work well or wore out too fast. I would call Covington and ask them what you need to do but am guessing dressing with something more aggressive will work.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Jan 24, 2011 10:38:28 GMT -5
Man, I had one of those saws too, till I got mad at it and killed it. The problem you are probably having is adjusting the amount of pressure you need to have on the blade. On it's own it'll cut OK for awhile , then it won't cut worth spit unless you add weight to the top. Add too much weight and it will glaze or dish your blade quicker than you can imagine. I finally made up lead filled socks at various weights for various hardness stones to adjust the downward weight but still, I never had a saw that ruined blades faster than that one and was messier to work with too. Plus a bugger to clean with that lift out tray and the damn sump pump would only handle the cleanest thinnest oil. Once a little sediment built up, it wouldn't cool the blade enough and it would bind in the cut. True story, that bastard screwed up one time to many and I put it in the driveway salvaged the motor and took a sledge hammer to it. With great satisfaction, I might add!. I expect you've applied too much pressure and dished or glazed the blade. If glazed, sharpening regularly might help. If dished, it's got to be straightened or thrown away......Mel
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spokanetim
has rocks in the head
Member since October 2009
Posts: 656
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Post by spokanetim on Jan 24, 2011 11:20:08 GMT -5
Damn, well this sucks! I was really thinking that as long as it was well cooled it wouldn't matter if it was water or oil. I'm sure I've applied to much pressure and dulled the blade, over and over again. I've went back to obsidian till I figured out the problem and even dulled it on that. I REALLY wanted to stick to water to keep the mess to a minimum but the best plans of can turn to crap. What about a big ass thiner 14" tile saw blade? I can see how going back to oil in this saw would be a cleaning nightmare, including the crappy lower pan design.
Mel, the funny thing was I bought before and started the project when I read your post in the 10" saw thread about your experience with a chop slab saw. I was praying that this wasn't the same saw that you took vengeance on. Now I understand why you killed it.
Tim
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Post by lonetreestudios on Jan 24, 2011 11:32:57 GMT -5
Not that this has to do with cutting performance, but be sure you are (at a minimum) running this thru a GFCI since the motor is not enclosed and I see there is water spray on the mounting. Having been on the receiving end of water induced shocks more than once (maybe that is why I haven't learned??!), they aint no fun! Also, assuming you are cutting with the spring in the straight position (2nd and last pics), not sideways on the adjustment wheel? Probably wouldn't seem like much, but at the end of an arm like that, you may be putting side load on the blade and adding to the problems. Nice looking set-up, hope you get it fixed and back up running..
Rodney
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spokanetim
has rocks in the head
Member since October 2009
Posts: 656
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Post by spokanetim on Jan 24, 2011 11:57:56 GMT -5
Thanks Rodney, yep I have a good breaker at the end of the cord. It's actually puts out little to no spray directly behind the blade, everywhere else is fair game. My plan was to buy a new 3/4 hp sealed motor once I knew it was all working properly. I use that little hook during cutting for a more direct pull straight down. My thought was the spring would only be needed at the beginning till mid way then the weight of the saw counter balance should have been more than enough force to continue the cut till the end.
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Post by bobby1 on Jan 24, 2011 12:12:47 GMT -5
The problem with using water on a larger saw is that it isn't a particularly good heat remover at the point of contact. What happens is that as the blade/diamonds heat up with more pressure the water flashes to steam (at the point of contact) and steam isn't a very effective heat conductor. As it gets hotter the blade gets duller rather quickly. Bob
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Post by parfive on Jan 24, 2011 12:23:11 GMT -5
Disregarding the blade, I see two issues here. Ken took care of the first one – you don’t run water in a 14” saw. The second one is the weight of the arm.
- You replaced a ¾ hp motor with a ½ hp motor. Did you weigh them? I doubt they weigh the same. If not, you threw off the designed balance of the machine, unless you changed the motor location to compensate.
- A lighter motor mounted in the same position would result in more weight on the blade – maybe good on a hard agate, maybe not. And you certainly wouldn’t need a spring adding more weight.
- A spring is not a constant tension device, so it’s a lousy replacement for a properly weighted arm. It’ll pull more when stretched out at the beginning of the cut, and decrease as the cut progresses and the spring gets shorter.
- You say the spring is “needed at the start as it's fairly well balanced.” That seems to confirm your setup is off. It’s not supposed to be balanced when the arm is lowered to the cut.
If you want, I’ll check my saw with a scale to see what the actual weight is when the arm is down for a cut. Gimme a holler.
Rich
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Post by texaswoodie on Jan 24, 2011 12:45:55 GMT -5
I beg to differ with the people who says water won't work with a 14 inch blade. I have a brick and block saw with a 14 inch lapidary blade that I use water with and it cuts great. BUT it has a 1 1/2 HP motor on it that dims the lights in the house when I turn it on. They ain't made a rock that it won't cut with water.
Curt
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Rockpox
starting to shine!
Member since March 2010
Posts: 38
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Post by Rockpox on Jan 24, 2011 15:56:28 GMT -5
I helped a friend with one of these. He insisted on water and ruined 2 blades. I found a 14 inch turbo tile blade on e bay that has lasted 9 months so far in his saw running water. the blade is thick (.100) for this small of a saw but it works. I would recommend oil if you want a thinner blade. I would also lose the spring and use a counterweight.
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Post by Jack, lapidaryrough on Jan 24, 2011 18:28:08 GMT -5
Lapidary Blade Speed Recommendations Blade BD-297 BD-301 BD-303 Series Recommended RPM Operating Range in Surface Feet Per Minute 3000 - 3500 3000 - 4500 4500 - 6000 Blade Diameter Approximate Arbor Shaft RPM Range 4" (102mm) 2860 - 3340 2860 - 4300 4300 - 5730 5" (127mm) 2290 - 2670 2290 - 3440 3440 - 4580 6" (152mm) 1910 - 2230 1910 - 2870 2870 - 3820 7" (178mm) 1640 - 1910 1640 - 2460 2460 - 3270 8" (203mm) 1430 - 1670 1430 - 2150 2150 - 2870 9" (229mm) 1270 - 1490 1270 - 1910 1910 - 2550 10" (254mm) 1150 - 1340 1150 - 1720 1720 - 2290 12" (305mm) 960 - 1110 960 - 1430 1430 - 1910 14" (356mm) 820 - 960 820 - 1230 1230 - 1640 16" (406mm) 720 - 840 720 - 1070 1070 - 1430 18" (457mm) 640 - 740 640 - 960 960 - 1270 20" (508mm) 570 - 670 570 - 860 860 - 1150 24" (610mm) 480 - 560 480 - 720 720 - 960 30" (762mm) 380 - 450 380 - 570 570 - 760 36" (914mm) 320 - 370 320 - 480 480 - 640
* Home o History o Contact o Warranty o Technical Library o Lapidary Dealers o Stone Dealers o Catalogs & Price Lists o Dealer Resources o Product Search * Lapidary * Stone
Then use, The Obsidian to sharpen blade.
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spokanetim
has rocks in the head
Member since October 2009
Posts: 656
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Post by spokanetim on Jan 24, 2011 20:48:08 GMT -5
Hey Rich, I checked the weight of the blade at the bottom of the cut and it's right at 2 lb's. I'd be very interested to know what your's is.
I'll swap out the spring for a weight system. The 1/2 hp motor that replaced the 3/4 is actually heavier so the weight shifted more to the rear. If you were to look at photo two the cutting arm is basically level, the balance point is only 20-30 degrees above level. After that it will tip back. Looking at the photo and thinking about that you can see that only the smallest of rocks would fit and not have it just tip back with little to no pressure on the rock without the spring or the addition of weight.
Sorry, forgot to add that according to the calculations it's spinning at 940 rpm.
Thanks for all the advice, still hoping to try and get this to work somehow without going to oil. Maybe I just need the 1.5 hp motor!
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Post by Jack, lapidaryrough on Jan 24, 2011 22:19:56 GMT -5
All diamond saws cut best at 5 - 7 minutes to the inch
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Post by parfive on Jan 24, 2011 23:39:25 GMT -5
Tim – I checked the arm weight in a couple of positions. Due to the swing arm geometry, it’s not constant, but increases gradually as the blade descends.
~ 6 ¼ lbs at 4” height, start of cut
~ 7 ¾ lbs at 2” height, halfway through
~ 9 ¼ lbs at 0” height, end of cut
Obviously, it’s your heavier motor causing the problem, with only 2 lbs at 0”.
Even on my saw, I occaisonally add weight(s) during a stubborn cut. I have some 3 lb galvanized steel blocks that fit my arm, and I’ll add one or two during a cut if I think it’s taking too long.
Rich
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Post by catmandewe on Jan 25, 2011 0:16:25 GMT -5
Your problem is the Covington gold blade. Get a different blade it will work just fine. I wasted alot of time and moolah to find out that they got a bad batch of blades. I am surprised they have not thrown the whole batch out. Maybe they will replace it for you. They replaced one for me, but the second one they would not replace. I replaced it with a cheap chinese blade that is still going strong.
Have a great day..................Tony
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spokanetim
has rocks in the head
Member since October 2009
Posts: 656
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Post by spokanetim on Jan 25, 2011 10:46:30 GMT -5
Hmmm, Thanks Tony. That could be the problem, the blade is a few years old blade but new out of the box. I'll give them a call. I have a feeling thats a big part of it.
Thanks Rich for taking the time to check your weights. Obviously my saw is not putting enough pressure on the stone. That spring I put on only makes 4 lb's pressure at 5", at 2" the spring has no effect, 1 lb pressure, and 2lb's at the bottom of the cut.
Makes me think a defective blade is more the problem than the setup. I gave it a good inspection and it's totally dull at the cutting edge. I can't see how with such little force, even with water, the blade could be wiped clean.
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Post by deb193redux on Jan 25, 2011 14:13:00 GMT -5
the diamonds are not wiped off the blade, rather the metal glazes over the diamond. more heat generally means more glazing.
does sound like you need to try a different blade
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Post by Jack, lapidaryrough on Jan 25, 2011 15:54:24 GMT -5
reverse the blade, then send it back.
In the 70s i bought a MK-18" 297, it was part of a bad lot. Piss`ed off employee did not add the 80-mess diamond to the metal bond.
I sharpen it, slab a 10 Lb. blue sheen on it. then a brazilian crap blade. I reversed it ran heel of obsidian two cuts.
Brazilian 1/2 inch into blade. I hang the damm thing on the wall. Where it is today
Oh I only well use MK-Blade, And Star Blades.
Jack
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