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[jalapeno333]

Hello,
I have an LST-12 Lortone 12'' slab saw.  I've noticed the slabs coming out with a tapered effect, thinner on one side than the other.  I've noticed, by stopping the saw mid-cut, that the blade is cutting crooked.  I've tried my best to start the cut withOUT the power feed turned on, so as to initiate the cut.. from what I can see, the blade is spinning straight, and the cut begins in a proper manner.

yet still, over time, the blade curves as the vice moves the piece through.  Picture of the bent blade included below.  Also, I removed the blade, and gave the arbor shaft a spin -- The arbor shaft appears to be wobbling, here's a link for a quick video of the Arbor Shaft spinning - https://vimeo.com/manage/videos/759670548

I'm wondering if I should replace the arbor shaft and bearings (i'm not familiar with the full terminology, or anatomy of slab saws) -- OR is a brand new blade is step 1?

and if i SHOULD replace the bearings/arbor/shaft, does anyone know where I can source a full replacement? 

thanks in advance!

[jalapeno333]

Update:  I've decided to order new bearings and bearings straps, found them cheap on ebay

https://www.ebay.com/itm/2-Pack-3-4-SBPP204-12-Pressed-Steel-Pillow-Block-Bearing-SBPP-204-12-ZSKL/172268410394?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649


Also, i will order a new shaft from Lortone
https://www.hplapidary.com/collections/ls12-arbor-parts/products/highland-park-arbor-shaft-for-ht12-and-lortone-ls12-slab-saws?variant=34563167158423


The flanges I will re-use, and I'm going to of course replace the blade:
https://www.ebay.com/itm/264769827601?hash=item3da582f311:g:rdAAAOSwuAVW1K5W&amdata=enc%3AAQAHAAAAoJ%2BaufIHGZ4d336d7YrIfBCEEeOcmochuUbmR6Tm2FyEUMjHkxZAKuo5kfv%2Fx3M%2BBh%2Fz2BHe47AJHMEQS33x3UF5216Xfy7wKz3svBHLhqiLS4qJBMTbojCJydVmqmJtWuYDxB3G%2BBsDY7i5Nkaf6w7CVxPzpWxvTLaC1ToR1TCd4U1%2Bf2tNXWJgDAQFhj5xVNx59tbgLsADJ5og99EnQ9w%3D%7Ctkp%3ABk9SR6jhie_5YA

[vitzitziltecpatl]

Good for you.

When you get it all back together, you'll want to check the alignment of the blade to the carriage travel.

[55fossil]

Great....  you might also want to check the rock vise for any looseness / wobble. Clamp a good size rock in the vise and see if it moves in any direction.

[bilquest]

Where to start...

Spitballing based on your images, especially the first one, I'd say the rock is moving in the vise.  There's a lot of torque applied by the power feed and if your rock isn't clamped down tight, it will move.  There's also potential alignment issues as previous posters have mentioned.

As someone who's lied awake in the middle of the night wondering why my LS-12 was doing this or that, I feel your pain.  For such a simple, yet elegant saw, the variables can seem unlimited.  My LS-12 is an ancient version (gunmetal gray) but I have replaced all of the guts, and even converted the A/C feed motor to a D/C variable speed.  It's taken several years to get command of my saw, but I'm stubborn and like to learn the hard way.

Also, for parts, Highland Park (hplapidary.com) sells most bolt-in replacement parts for the LS-12 and their prices are decent.

Good luck, and let us know if you need any more ideas.

[R.U. Sirius]

I agree, there are lots of plausible explanations. To add to the list of usual suspects, a dull blade and/or too viscous oil will increase radial force on the blade, and eventually something will have to give - the rock will move in the vise, the blade will deflect, bearings will drift, carriage rails will deform...

What kind of oil are you using?

[jalapeno333]

What kind of oil are you using?

I am using UltraPro Food Grade Mineral Oil
https://www.amazon.com/dp/B00VNI1JI0/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=1c327ef98beaf8897a2940d40bc03468&content-id=amzn1.sym.cf8fc959-74aa-4850-a250-1b1a4e868e60%3Aamzn1.sym.cf8fc959-74aa-4850-a250-1b1a4e868e60&hsa_cr_id=4777212590401&pd_rd_plhdr=t&pd_rd_r=93567e45-2ae0-4977-9cf1-f369ec9cba8c&pd_rd_w=t1jzC&pd_rd_wg=s0orV&qid=1665780618&ref_=sbx_be_s_sparkle_atgssd2_asin_0_title&sr=1-1-9e67e56a-6f64-441f-a281-df67fc737124

[jalapeno333]

  My LS-12 is an ancient version (gunmetal gray) but I have replaced all of the guts, and even converted the A/C feed motor to a D/C variable speed.  It's taken several years to get command of my saw, but I'm stubborn and like to learn the hard way.

thank you kindly for the suggestions, and also I'm wondering if you were able to view the video in my original post?  The arbor shaft appears to be gunked up, and as it's spinning it also seems to have a wobble.  What do you think?

Arbor Shaft Video: 
https://vimeo.com/manage/videos/759670548

Thanks again!

[bilquest]

I didn't see the video the first time, but watched it now.  You definitely have a wobble, but it's difficult to determine if it's a bent shaft or bearings.  If that clunking noise is coming out of the shaft assembly I suspect bearings.  If you can remove the bearings from the shaft and roll the shaft on a smooth surface it should roll true (no wobble.)

[R.U. Sirius]

That oil is 11-14 cSt viscosity, ideal range for rock cutting is said to be in the 5-7 cSt range. Not too far off, so likely not a problem, unless you were cutting in a really cold shop.

[vitzitziltecpatl]

Thanks for posting that "ideal" range for rock saw oil.

The stuff I've been using is 15.3 mm2/s - which appears to convert 1:1 to cSt. Have been happy with it, but now I'll pay more attention to that 5-7 target range.

[R.U. Sirius]

Thanks for posting that "ideal" range for rock saw oil.

The stuff I've been using is 15.3 mm2/s - which appears to convert 1:1 to cSt. Have been happy with it, but now I'll pay more attention to that 5-7 target range.

Unfortunately, we have to walk the fine line between cutting performance (the lower the viscosity, the better), and reducing oil mist (higher viscosity means less mist). Even without rocks involved, inhaling oil mist can lead to serious health issues. Add to this silica dust carried by tiny oil droplets, and we have a real hazard to address.

I prefer low viscosity mineral oil, with slower blade rotation to minimize misting and a patient 5-minute wait before opening the lid. I am even considering building a mist scavenging system (simple air circulating system with a coalescing filter cartridge to capture mist, connected to the saw enclosure).

[irockhound]

Late reply since we have been traveling.  I have had the same issues with my Lortone LS12.  One thing I didn't see mentioned is the blade sharpness.  This is a common cause of the tapered cut you describe.  I have tries the sharpening stones sold by kingsley and rio and Obsidian, old SIC wheels etc.  After getting turned on to sharpening the blade with the edge of a rasp file my saw always cuts true.  Obviously if you have worn bearings and an arbor problem fixing those first is critical.  One thing I notice is the difference in sound the saw makes before and after "sharpening" the blade with the file. All you are really doing is exposing new diamond edges by tapping the edge with the file.  Lots of vid on you tube about this method.  Lapidary channel, Highland park and many other YouTube sources.  After Highand drove Lortone out of the saw market I bought 3 extra arbors, feeds rods, bushings etc.  Bearings are easily available everywhere so I just keep 2 sets on hand for those.