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Post by stardiamond on Apr 17, 2015 14:02:42 GMT -5
After buying it seven years ago - I made my first cuts. This is a chunk of blue biggs that I don't want to cut until I have it figured out. First slabs are Laguna lace bubble agate. Everything was fine except getting the thickness right. Ill be able to use three of the slabs. Next cut was Owyhee which was uneven but I can use it. The clutch disengaged before the cut was complete. Next cut was condor agate and the clutch kept disengaging when cutting. The rock was secure in the vise. Do I need to cut a clay brick so soon after this few cuts? What else could be wrong? The blade was a new MK 301 that came with the saw?
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,640
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Post by QuailRiver on Apr 17, 2015 14:13:47 GMT -5
Do you have the feed speed set on the slowest speed? Larry C.
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Post by stardiamond on Apr 17, 2015 14:58:22 GMT -5
I called Covington and they said that the blade needs to be dressed and recommended 200 grit silicon carbide. They confirmed there is no speed control on the saw. I know that blades need to be dressed. I just didn't expect after so few cuts. They say it is normal when cutting hard material.
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Fossilman
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Member since January 2009
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Post by Fossilman on Apr 17, 2015 15:15:34 GMT -5
I can cut quite a lot of rock-agates and petwood too,before I need to dress the blade..
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,640
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Post by QuailRiver on Apr 17, 2015 15:17:33 GMT -5
Well if there is not a variable speed that rules that possibility out. It's difficult to determine scale in the photos but those rocks don't look large enough that you would need to be dressing a brand new 14" MK 301 blade after only five or six cuts. Are you sure your blade is a MK 301 and not a Covington 301 blade? If it is a MK 301 blade then the only other thing I can think of that might be causing this is that the slip clutch is set to slip too easily and needs adjustment. Larry C.
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Post by stardiamond on Apr 17, 2015 16:18:06 GMT -5
The first cuts went well. I ordered some dressing sticks from Covington. The blade is MK. I'll dress the blade when I get the sticks and if it doesn't resolve the issue, I'll try to adjust the clutch. The blade is 16" and the rough was under 4". There seems to still be a lot of paint on the blade. Maybe it needs a break in period and will get better.
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,640
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Post by QuailRiver on Apr 17, 2015 16:28:27 GMT -5
The first cuts went well. I ordered some dressing sticks from Covington. The blade is MK. I'll dress the blade when I get the sticks and if it doesn't resolve the issue, I'll try to adjust the clutch. The blade is 16" and the rough was under 4". There seems to still be a lot of paint on the blade. Maybe it needs a break in period and will get better. Not being confrontational but paint on an MK blade? MK hasn't painted their 301 blades for many years. What color is the Paint? If it is red it may be an old MK blade but if it is gold it is probably a Covington Blade. But either way with a new painted blade you should always cut through a brick or dressing stick before you start cutting rocks with it to remove the paint from the cutting edge or the paint can gum up and interfere with the cutting action. Larry C.
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Post by stardiamond on Apr 17, 2015 16:49:24 GMT -5
I'm kind of color blind. The blade is painted a deep red/brown. The blade was purchased 8 years ago and not used until yesterday. The Covington instructions are very limited. I have no experience cutting with a saw like this. The paint issue makes sense to me. Nothing was mentioned regarding pre cut dressing.
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QuailRiver
fully equipped rock polisher
Member since May 2008
Posts: 1,640
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Post by QuailRiver on Apr 17, 2015 16:55:08 GMT -5
Yes that is one of the old MK 301 blades from when they were still being made in the U.S.A.. That should be a very good blade. So I would just try dressing it a couple of times and then try cutting again. And if the clutch is still slipping then try tightening the clutch adjustment. Larry C.
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Post by Peruano on Apr 17, 2015 17:37:31 GMT -5
Fine advice, but the Covington drive system is a bit of a mystery so some experiments might be in order. 1. I'd start with a small rock. Does it cut well now? 2. I'd dress the blade or cut something soft like a rhyolite or jasper that is known to be on the soft side. Does it do the job here? The Covington drive is a constant speed but with the clutch it presumably is designed to slip a bit on tough stuff, and drive on through when dealing with softer or smaller, or easier stuff. So check this using different sized, and hardness of rocks. If the clutch slips on all of of them or those that it should plow through then tighten it a bit. Hold the drive rod and turn the nut at the far end of the shaft clockwise to tighten, counter clockwise to loosen. If that does not help, you may have to disassemble and make sure the clutch is OK. There is a set screw in there that if loose will allow the clutch to slip excessively. Usually a result of abuse by a prior operator. Go slow and go analytically. Keep us informed. tom
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Post by jakesrocks on Apr 17, 2015 17:41:53 GMT -5
While you're waiting for your dressing sticks to come in, if you have a hunk of plain old black obsidian laying around, make a few cuts through that. It works just like a dressing stick, and plain black obsidian is cheap.
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QuailRiver
fully equipped rock polisher
Member since May 2008
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Post by QuailRiver on Apr 17, 2015 18:16:02 GMT -5
One other thing I just thought of that should have been one of the first questions I asked; What type of coolant/lube are you using? Larry C.
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Post by stardiamond on Apr 17, 2015 18:22:52 GMT -5
I don't have any obsidian. I have hundreds of clay bricks. I've waited a long time to use the saw and don't mind waiting a little longer. I feel pretty good that the dressing sticks will resolve the problem. I would think that when it left the factory everything was set up correctly. When I bought the saw I thought it was the best new saw for the price range I was looking for. The feed system is a mystery to me also. To activate the feed you attach an alligator clip to the threaded rod on the feed system. The first 5 cuts, everything worked fine.
I have been getting some good experience using it without wasting much material. I've got some bruneau where I want to get the cuts exactly right and a lot of the rough is uneven and not large. I need to start experimenting with wedges and a slab grabber to get the cuts lined up correctly.
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Post by stardiamond on Apr 17, 2015 18:27:33 GMT -5
One other thing I just thought of that should have been one of the first questions I asked; What type of coolant/lube are you using? Larry C. Covington Rock Hound oil that I ordered with the saw. The shipping was either free or discounted when I ordered the saw. The best news I got was that the saw is relatively quiet. My lapidary area is outside the master bedroom and grinding cabs is a lot louder.
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QuailRiver
fully equipped rock polisher
Member since May 2008
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Post by QuailRiver on Apr 17, 2015 18:46:20 GMT -5
One other thing I just thought of that should have been one of the first questions I asked; What type of coolant/lube are you using? Larry C. Covington Rock Hound oil that I ordered with the saw. The shipping was either free or discounted when I ordered the saw. The best news I got was that the saw is relatively quiet. My lapidary area is outside the master bedroom and grinding cabs is a lot louder. Just wanted to make sure you weren't using a water based coolant with a saw that large. I've got two Covington 20" saws that I bought used. Both have variable speed belt/pulley systems. I always run them on the slowest feed setting. One of them had some clutch slipping problems when I first got it so I disassembled the clutch system, cleaned it, and reassembled it and tightened it up a bit tighter than it had been and so far so good. Larry C.
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Post by Rockoonz on Apr 17, 2015 18:46:58 GMT -5
The old style MK301 is a great blade, the 14 inch blade in my old Highland park has been super. Sorry Don, don't want to argue but while obsidian does a great job of cleaning residues from blades, it will not sharpen them. It's not abrasive. You can prevent a blade from needing sharpening with obsidian, but it will not remove steel.
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Sabre52
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Me and my gal, Rosie
Member since August 2005
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Post by Sabre52 on Apr 18, 2015 7:59:36 GMT -5
I run a ten inch Covington and for best results, I dress my blade very three rocks or so which means maybe 12 cuts or so between dressings, That really helps a bunch. I use cheap medium grit SC wheels which cost about $5 each and will do a whole lot of blade dressing per wheel. Regarding the clutch, well that still remains a mystery to me. I'll tinker with it and think I have it set and then it will stop cutting. Then I tighten it a bit and it starts cutting again. I seem to have it adjusted pretty well now but it took a lot of experimentation. When cutting agate and such, you definitely want it set at the lowest possible pressure that will still cut at that constant feed rate. My power feed seems to overheat and shut down a lot in hot weather too but that's another issue. Hopefully that will not be a problem with your rig because here in hot Texas, that is a real constant pain in the ass.....Mel
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Post by roy on Apr 18, 2015 11:27:23 GMT -5
i would switch to the mk-303c i never have hade a crimped rim blade that has worked well for me ! also if you dont have obsidian just pay the shipping and i will send you some i have way more than i need
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Post by Rockoonz on Apr 18, 2015 13:18:43 GMT -5
roy it's not a crimped rim it's the old style continuous rim. I cut lots of brazilians and everything else with the one on my 14HP. The 303 might be more aggreeable with the Covington clutch though, judging from what my saws sound like when I switch over the 303's cut quieter which probably means less effort. Plus they can run faster rpm but with the Covington that also means faster feed if you don't change pulleys on both blade and feed.
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Post by stardiamond on Apr 18, 2015 14:31:35 GMT -5
The blade I have is suppose to be good. I'll give it a chance. I generally don't like crimped rim blades. The first trim saw I had was crimped rim. I also bought a slab saw that was suppose to be 10" but was only 8" and I used a 9" crimped rim blade. It had a gravity feed and didn't cut worth a darn. I got rid of it. The Genie trim saw attachment uses a 8" mk continuous rim blade and it trims like cutting plywood. Blade life was good except when I started using it for slabbing. Even though I didn't force it, I probably fed to quickly and that led to shortened blade life. I'm sure that a continuous rim MK will work very well with my Covington, I expect to need to replace blades more frequently. My dressing sticks should be here Tuesday and I'll see what happens.
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