cherdarock
starting to spend too much on rocks
Member since December 2012
Posts: 140
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Post by cherdarock on Feb 23, 2013 0:49:09 GMT -5
If you read the title of this thread, THAT is what I had the pleasure of hearing last night on the ol' slabber. SO this is to remind folks to double check the rock in the vise, sight EXACTLY where the cut will happen, and ask, "WILL the kerf affect the strength and integrity of the stone? I was slabbing a piece of wonderstone. I had a good bite at the vise, but I didn't site the cut prior. I had a bite that was actually a little overhang, :nono: and I was cutting the second slab, which was pretty close to the visejaw edge. The stone cracked, "gong" wanged the blade, and forcing the bulk of the rock between the blade and the jaw edge, jammed SO HARD it took about 5 mins. of finesse to work it free. a cursory spin of the blade indicated a problem. The actual force: 1) Stopped the blade so fast, the pully set screw cut a distinct groove on the shaft as the pully took two and a half revolutions to realize the blade was stuck. 2) forced the shaft AND bearings to shift in the pillow block. The pully couldn't follow, and so that set screw groove was cut into the shaft like a screw thread!!! I finished off last night and part of today doing a rebuild. OH! the pully jammed up so hard I had to unbolt the table hinge from the sump box to seperate the table from the plastic sump tub. All is working fine now, (little worse for wear?) THANK THE LORD! I tell y'all whut, Gonna be checkin' that ol' saw/rock/setup REEEEEELLLLLLLY dang good from now on... :blush: The "Bnnnn" was the sound of a 3/4 hp motor suddenly meeting a "torque defyer" and stopping dead, but not giving up. "takata takata" is a noise you do NOT want to hear when you try to spin your slabbing saw blade. Oh, I was REAL quick shutting her down, yesseri bob! Be careful out there YAH? ;D
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rxscram
has rocks in the head
Member since August 2011
Posts: 513
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Post by rxscram on Feb 23, 2013 1:19:44 GMT -5
Wow, glad everything worked out okay. I guess that's another great reason not to walk away from your slab saw when it's cutting.
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jason12x12
freely admits to licking rocks
Member since October 2011
Posts: 798
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Post by jason12x12 on Feb 23, 2013 1:48:08 GMT -5
sounds terrible!! im pretty good about double checking, but that doesnt mean accidents could happen even with all the prep in the world..just like anything.. cut rock one slice at a time
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Post by sheltie on Feb 23, 2013 9:28:03 GMT -5
Yesterday must've been a bad day for blades. You were lucky. The cookie monster took a bite out of mine and I have no idea why.
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Post by Peruano on Feb 23, 2013 10:38:31 GMT -5
I'm not sure I understand what happened. There is always a chance that the rock will break and or give way out of the vice and rock down against the blade (wedging or not). I'm not sure what sighting you failed to do that caused the problem. Did you cut a wedge instead of a true slab that was more prone to breaking off early? Having the vice close to the blade is something that will occur as you try to get the last slabs (unless you can project it away from the vice using a stub to hold the specimen). I'm sure that we could all benefit from your scare and efforts, but might benefit from an expanded description of the circumstances. Thanks and I too am glad things worked out eventually. Tom
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rockingthenorth
fully equipped rock polisher
Member since January 2012
Posts: 1,637
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Post by rockingthenorth on Feb 23, 2013 11:05:20 GMT -5
glad you got it fixed and your back to slabbing
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Feb 23, 2013 16:08:35 GMT -5
sheltie - Did you cut through a fracture that was at a very low angle to the blade? Sometimes When that happens a small piece of stone inside the large stone will come loose and wedge the blade in the cut. I have never had it bite a chunk out of the blade but it has tweeked the blade a little and if the stone would have been more solid I think it would have taken a piece out of the blade. When mine happened it just broke the slab and wore a groove in the blade. It you can see where a small wedge hole in the slab or mother stone there is a good chance that is what took the bite out. It must have made a hell of a racket after the big bang. Jim
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Post by sheltie on Feb 23, 2013 16:57:52 GMT -5
No, I was just cutting through a piece of fortification agate. You know how the sound of the blade changes a little just before it completes the cut? That's kinda like what it sounded like although I knew it was way too soon for the cut to be completed. I shut it off immediately, but as you can see the damage was already done. I've never had any problem with it with any rock before so I'm guessing there was a flaw in the manufacturing of the blade. Incidentally, the blade was brand spanking new less than five months ago.
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cherdarock
starting to spend too much on rocks
Member since December 2012
Posts: 140
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Post by cherdarock on Feb 23, 2013 18:26:49 GMT -5
Sheltie, I do a lot of metal work, THAT fracturing of the blade looks to be from the manufacturing end. The alloys used, along with the processes for annealing and hardening leave opportunity for flaws, and it requires two or more types of inspection per operation to detect. NOTE how the fracture doesn't extend beyond the segmented section. The rim work had a flaw. I am willing to bet that if you took the blade to a lab that works with alloys and exotics, they would find at least one more flaw on the segments. Sometimes flaws sneak past, and the results can be catastrophic! I like the pro-slicer. Less than 1/16" thickness, continuous rim, and the one that got jammed FORTUNATELY didn't bend or tweak. Mine has over 300 cuts, ALOT of "barely fits" and a very wide variety of materials. At first glance the P-S looks like a disk of flimsy sheet metal with a bit of grit glued to the edge, but the blades have suprised me. OH! My saw has the "threaded auto-feed". I modified the feed with a DC motor, and use a switchable (+to-) DC transformer that has multi voltage options. This allows me to reverse, speed up or slow down the feed according to the material, with a simple flick of the switch. I also put a beefy 3/4 hp for the drive (still @1725 RPM) The blade company notes that the 10" P-S CAN be run efficiently @ 3450, so I may go and p/u some pully choices, but the big at the motor-small at the shaft will cost me in torque. I have a 2 hp 3450 but I don't know about that much hp considering what just happened...lol I really DO enjoy the feed options tho. I can creep along on brutally tough agate without over feeding, and I can breeze through the small stuff incredibly fast. I'll have to getcha VIDEO! Careful with your cuts, glad there wasn't any horror stories (yet?) All it takes is the picture of someone with a half a blade stuck in the chin and a doctor shrugging his shoulders to make me dread switching on for a cut... Peruano: It was the shape of the material: ------------------- ^ --------------[___]^ The view is top looking down, the two arrows are the vise, and the bottom right is a protrusion. The saw was almost through the protrusion, which didn't have enough strength. the rock collapsed, and fired the main rock body in between the right vise jaw and the blade. What I should have done is site up from the top looking STRAIGHT down, to ascertain where, exactly, the blade was going to slice. I normally do that, but when I am lazy, I know the number of turns needed to advance the vise for 1/8" slabs, (2 turns) 1/4", (4 turns) or 3/8" (6 turns) and also I just slid the vise table to make sure the blade cleared the jaw, before engaging the half nuts. DOH!
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cherdarock
starting to spend too much on rocks
Member since December 2012
Posts: 140
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Post by cherdarock on Feb 23, 2013 18:33:03 GMT -5
One more thing, I also made a lexan box top lid for the saw. Clear and 3/8" thick at the top, it is alot more sturdy than the 1/8" thick molded poly carb plastic the saw came with... ;D ;D ;D
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Post by Peruano on Feb 23, 2013 19:29:46 GMT -5
Cherdarock, Thanks for that explanation. I like the idea that I don't stand in line with the blade rotation and take some confidence in the fabricated top that I'm using is a heavy duty Rubbermaid travel trunk and pretty tough. While some folks say they don't need "no stinking window", I like having a chance to watch what is going on when the saw starts to sing louder than normal or reaches a critical stage. Sometimes I have to illuminate things with an additional shoplight but its nice to see if sparks are flying or my specimen has shifted. Stay safe and work safely. Tom
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Post by Rockoonz on Feb 23, 2013 21:15:01 GMT -5
I am leery of motor driven screw feeds. Problem is when the saw stops spinning the feed does it's best to bend the blade. A belt running off the arbor shaft will stop the feed if the blade stops. My 10" slabber has the rotissere motor drive and it choked on a piece of Bruneau and ruined a blade.
Lee
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Post by johnjsgems on Feb 23, 2013 22:03:15 GMT -5
Sheltie, you could probably benefit from contacting BD/Mk to see about a warranty. You would have to download an RMA request form and jump through the hoops but if defective they will replace it. Especially if there is no apparent blade damage.
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cherdarock
starting to spend too much on rocks
Member since December 2012
Posts: 140
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Post by cherdarock on Feb 26, 2013 1:26:09 GMT -5
Rockoonz: I understand the feed worry, but that is why I modified the feed, (motor/electrics) I will say this, looking at the switch box, there is a big hole in it. The original motor had issues... ENTER... the HAND CRANKED FEED! Yes for about 15 or 20 cuts back in the 90s, the ol' slabber was hand cranked. Each crank of the handle was the muttering, "GOTTA make this autofeed work. WORK AWESOME!" :drool: tell ya whut, RARELY get a stall, binds only when I don't have a rock that the vise can find 3 points, (or has an overhang in conjunction with lazy slab-daddy) and only a lil nub on the slab after the cut. Must admit, with hand cranking, you develop a "feel" within several cuts, and the only inconvinience is that the second you start cranking, EVERYTHING is somehow beyond reach. Energy drink, shop rag, cell phone, smart-asses watching...
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Post by sheltie on Feb 26, 2013 9:32:34 GMT -5
Sheltie, you could probably benefit from contacting BD/Mk to see about a warranty. You would have to download an RMA request form and jump through the hoops but if defective they will replace it. Especially if there is no apparent blade damage. Hi John, Since the blade came with my new saw (HP), I took it to John Rowland and he is handling it for me. Denny
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Post by Hard Rock Cafe on Feb 26, 2013 9:36:40 GMT -5
I've had more problems cutting rock with my 10" saw than my 18". The vise on the 10" isn't as good and there just seems to be fewer good contact points on the small rocks, unless you make some blocking cuts.
For reference, I use a 1/2 hp motor on my 10" Star Diamond and a MK 303 blade. (In the past I used a 1/3 hp motor without issue.) The saw has an auto screw feed with a little motor. One of the nice features is that it uses a wood block to engage the screw feed. If I adjust the contact between the wood and the screw correctly, the block will slip if the blade stalls.
For a cut like you described, I would normally flip the stone so that I'm cutting from the end, rather than the middle.
Chuck
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True Grit
noticing nice landscape pebbles
Member since January 2013
Posts: 76
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Post by True Grit on Feb 26, 2013 18:06:15 GMT -5
Can I use the title of this thread as my ring tone? Glad its up and running again. Thanks for sharing too, something to keep in mind when/if I get a slab saw.
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