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Author Topic: Free jasper/agate/other for helping with 18” slab saw questions  (Read 641 times)

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Craigab

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After 2 weeks, I finally am about done redoing  an old rusted out 18” slab saw.  I purchased an 18” 301 Gemking blade from mk Diamond and will be buying another 18” 303c shortly. I have never slabbed before but want to try out the different blades to see how they cut as well as noise level. If you have experience please feel free to chime in. I know they run at different RPM speedss based on manufacturer recommendations.   I have a few questions that I would greatly appreciate someone chiming in on.

I installed a 4rpm power feed motor which I have added regulars pulleys to slow down the feed to about 6-7 inches an hour. Is this too fast for hard stones?  What will happen if it is? Will my saw blade be ruined or will the blade  motor just stall out?  Should I leave slack in the power feed belt to allow slipping?  Do most saws have some kind of clutch pulley?


Second question,  Do you usually alternate the speed of the saw blade motor.  If you do swap out the pulleys to adjust the speed what factors go into this consideration. MK Diamond says the 301 should run between 640 and 960rpm and the 303C between 960-1270rpm for 18” saw blades.  I bought many pulleys to make sure I had what I needed just wasn’t sure what is ideal. I was going to start the 301 at 800rpm, does that sound resonable or should I start at the high or low end? 


Third question, I am using an arbor adjuster washer because my saw has a .75” arbor and mk diamond only sells 1” arbor saw blades. mk Diamond sent me a copper or brash washer, how do I install this, by hammering it in? Secondly, will this pop out as my saw blade is held by two discs on either side which sand which the blade. However, the discs have recessed centers that are recessed far enough the washer could easily fall out into the recessed area. Do I need to purchase these discs without the recessed area toward the center so they sandwhoch the blade all the way to the arbor shaft rather then just on the outer 1/2 inche of the disc. See photo for details.


Last question, anyone know where to buy a saw blade splash shield as mine is rather rusted, sharp, and doesn’t go up as high as some of the models I have seen. Want to make sure I can see inside the window.

Thanks for your help and I am happy to buy anyone that answers these questions a stone on the major online auction website  up to 10$ for the help. Just pm me your address and the item number and I will bid or buy it. Thanks a bunch, I would have never been able to get my saw running without reading online forums like this.
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Craigab

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #1 on: May 15, 2018, 01:46:05 PM »

Pictures
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irockhound

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #2 on: May 15, 2018, 02:00:14 PM »

Not sure about a true splash guard but an old bike tire fender works great as a guard.
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Sapphireminer

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #3 on: May 15, 2018, 04:30:17 PM »

Hi I have cut alot of hard stone using mk303 its a quite cutter and leaves the stone with almost a pre polish finish. I have just changed over to a 301 its quiet noisy compared to the 303 but it is better suited to hard stone as the blade has a higher carbon content making it a stronger blade. It to leaves a very smooth finish on hard stone. The finish will also depend on your saw condition not just the blade.
Dave
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Craigab

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #4 on: May 15, 2018, 04:46:05 PM »

Thanks, what factors would go into a saws condition to effect cuts?  I have replaced all the bearings and am replacing the cross feed stainless steel rails in the carriage as well as adding bronze bearing sleeves for the two cross rails to help eliminate wiggle. Saw shaft and power feed bearings were all replaced and are tight with no wiggle. Any other considerations?  My saw has a steel bar frame so I assume it has not warped and wouldn’t know how to check if it was.  Do people usually use a gauge to measure the saw blade angle to carriage?  Was planning on using anti vibration rubber pads for the feet unless people think that might make it worse by causing movement/flex
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Sapphireminer

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #5 on: May 15, 2018, 04:48:04 PM »

A bit more info if you have a cover over your machine you will not need a spash guard on the blade the only time the oil spraying onthe sight window is a problem is when the oil becomes dirty and I take it as time to give the saw and oil a clean out as far as rock feed  time if you check online with saw companies like Lortone etc and see what speed ther saws are set at unsure what speed mine is but probably 30mlm for 7 inches will check next week when home. The arbor adjuster washer should be a firm push in by hand and you  can put a little locktite on it to make sure it doesnt move.
Dave
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Sapphireminer

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #6 on: May 15, 2018, 04:54:18 PM »

Sounds like you have the machine set to a high quality even if the blade an carriage  was out a small amount as long as it was consistent for the full length of travel after the first cut all the slabs would be exactly the same so no problem. My saw just sits on a wooden bench no rubber as long as all pulleys are true should have no vibration.
Dave
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Craigab

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #7 on: May 15, 2018, 05:03:26 PM »

Thanks again. Do you know if the arbor ring actually have support during cuts or is it only during mounting until the outer ring of the two contact bushings then provide the support. I will take your suggestion with locktight. I was thinking of using a thin piece of plastic to fill the void in the two flanges to make sure the thin arbor bushing could not squeeze out to the side. However u am concerned they may have left the centered hollowed out to avoid stress at the inner section of the blade so I would need to be careful with not being thick enough that any pressure could transfer to center when flanges tightened. I just want to make sure blade arbor bushing doesn’t hop off during a cut as I imagine that would ruin the blade by causing a hula hoop type spin. Thanks again for the help.  I did check with Covington for the power feed speed and they recomended 7” per hour as “slow” and up to mid 20” as fast. I just wanted to get other people’s experience before I start to see if this ball Park was correct. I’m going to be cutting 4-5” thick jasper when I start. I may even try slowing it down with a larger pulley till I get the hange.
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Sapphireminer

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #8 on: May 15, 2018, 08:43:42 PM »

I believe that the flange does all the work on the blade and the insert is to true the blade when fitting I never had any trouble with the insert on the 303 but put a little locktite on the 301 which is no problem if you dont want to change blades to a different saw with different arbor size.I dont see the slow travel speed as a problem it would put less pressure on your blade but if you are cutting a lot of larger slabs you will need a lot of time.
Dave
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Slabbercabber

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #9 on: May 16, 2018, 05:16:16 AM »

The plastic is a good idea.  I use arbor shims that give me a small clearance overall for the same purpose.  I wouldn't trust Locktite in this instance.  If the spacer does slip out, the blade will most certainly move under the pressure of the cut.  The blade must be as close to perpendicular to the motion of the carriage as possible.  Any misalignment will cause the blade to bend as the cut is made.  The bigger the material, the greater the flex.  This will eventually cause the blade to cup and become useless.  The best way to check is with a machinist's dial indicator but you can put a pencil in the vise and run the vise up and back until it makes a solid light line all the way across the blade.  Also, if this is not right the slabs will show saw marks.  Since my oil runs through a cascade system and pump, it is always clean.  Nonetheless, I still run a bicycle fender to deflect it away from the window.  A clean window is always better than one covered with oil.  It sounds like you are doing everything needed to make the carriage run true.  That is important.  Putting the entire machine on rubber may have some effect on noise but I doubt you would notice the difference.  The noise comes from the sides of the blade abrading the stone without force.  The blade then acts as a speaker.  The only thing I have found that can have any effect on the volume is turning up the amount of oil sprayed on the blade, dampening the noise at it's source.
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peruano

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #10 on: May 16, 2018, 05:37:47 AM »

The copper insert provided is good but can be bolstered if too thin with other "arbor bushings" available at Lowes or any good hardware store (primarily to hold the good one in place as you have pondered). 
Speed can be varied but the slow speed that works well for your biggest and hardest rocks will work for all others.  If you know you are cutting small and soft all day or week it may be worth speeding your saw up to save time.  7 minutes per inch is a good speed.  I suspect you are overthinking blade speed too.  960 is the overlap speed and probably 800 is fine for either blade as well.  Its the extremes that you might not want. 
I use a motorcycle fender for a blade guard (diverts the spray back onto the blade).
I'm not sure that you have a top, but if not you will want some shields on the sides to control spray as much as possible.  There is a H shaped aluminum bracket made for shower stall installations (basically a slot on each side to connect two pieces of glass or plastic).  It makes a great holder for plexiglass panels and can be quickly moved to accommodate arms, weird sprays etc.  One slot goes on your tank top, the other holds the plastic panel. 
If you are worried about your set up run a few small rocks first to gain confidence - - then drag out the big agates.  Good luck.  No free rock for me. . .  just show us some photos of your progress and share your hounding successes down the road. 
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Craigab

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #11 on: May 17, 2018, 03:13:15 AM »

Thanks everyone for your help, I added the blade last night and it was wobbling like crazy. Turns out, the bushing they gave me had about 2mm of clearance causing the blade to be slightly off center from the shaft. This resulted inter blade to rise and fall slightly as it spun in a hula hoop manner. Obviously not good. will have to get a better fitting arbor adjuster before can try again.

I was wondering if most people lock down the cross feed/slab depth spinner before a cut. Does the vibration of the motor running cause the depth to change at all during cuts if your don’t?  My carriage does not have anything to do so and if most do I may add something. It’s not excessively loose but also not tight either. Once I install the two bronze bushings on the two carriage cross bars I am hoping it solves the wobble problem I have as the cross feed on the carriage teeters ever so slightly on the two cross bar slide rails on either side of the cross feed screw due to the holes being a tiny bit wider then the cross bars
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Slabbercabber

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #12 on: May 17, 2018, 05:16:24 AM »

Once the blade engages the rock, that interlock will stabilize the crossfeed.  There should be no vibration in any case.  As this is essentially a grinding operation, a nickel should stand on edge on the machine while it is running.  Unfortunately, belts do add some motion so this is seldom achieved in practice.
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peruano

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Re: Free jasper/agate/other for helping with 18” slab saw questions
« Reply #13 on: May 17, 2018, 05:38:26 AM »

Not all saws have a set screw to lock the cross feed mechanism, but many do. I'd say watch your cross feed handle and if it moves much during a long cut, you may need some locking mechanism.  I have an HP saw that even with a lock down screw on the cross feed, the handle migrates to the 06:00 position no matter where it starts out.  Maybe its just the handle but if feels funny to find it moved.  I agree that a bit of slop in the vice sled probably is not of concern.  The blade contact with the rock will tighten it all. 
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