Lapidaryforum.net
Gadgets, Gizmos, and Dohickeys => Cutting, Grinding, Polishing => Topic started by: lithicbeads on August 26, 2016, 10:36:59 PM
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I have a friend who has a saw that is leaving saw grooves in the finished slabs. No cupping problems and the feed rate is standard. Any idea of a cause?
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I can think of 2 possible reasons.
#1- Vise carriage is loose on its rails, allowing the vise to shift very slightly.
#2- Too fast of a feed rate on the saw vise. As the vise moves forward, too fast of a feed will cause it to stop from time to time.
I'm sure others will chime in with other possible causes.
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I would also check for warped blade and worn arbor bearings. But I agree, worn carriage bearings are the most likely.
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Arbor bearings is my guess or the bearings on the vice carriage. The blade warp or being dull will normally cause curved cuts but not grooves unless the material has varied hardness's through the stone.
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i would tap the face of the cutting edge to bring out a sharper cutting edge.
Mine does that, i stop cutting, break out the tiny hammer and sharpen my blade with it, tap tap tap all the way around and start cutting again.
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Looks like the blade might be out of alignment with the carriage.
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Usually a clutch slipping or a feed dog slipping on the feed screw, might need a tighter spring.
Depends on the make.
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In six responses, you received a pretty broad and accurate picture as to what causes saw marks. Ultimately it is 1). surges in the feed rate (clutch slipping etc.) which can result from 2). dull blade making the feed faster than the cut; or 3) an alignment problems causing the blade to bind (and thus surge periodically); or 4). a bent blade (causing the blade to tend to bind); or 5). bearing problems causing similar issues. Its all important and relevant. Ain't knowledge wonderful; lapidary is a mental challenge.
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One more to add regarding feed rate slippage. I have a very "tight" alignment on my saws which both have been modified by me to keep things tight and adjustable.
1) When I see any misting occurring (results in slight saw marks) I know the blade needs sharpening.
2) When I am moving the carriage to start a new slice I make sure it still glides on the rails. If it is tight I use lithium grease spray on the rails and threaded bar. On my tight carriages I need to grease the treaded bar and rails every 5 to 10 cuts depending on the size rock and hardness. On VERY large rocks I use the lithium spray on every slice on the 24 inch saw.
3) When the locking mechanism for the carriage to the threaded bar gets to taking a full half turn to lock I tighten the adjustment screws enough to take 1/3 turn. I do this by getting the carriage aligned to the bar to get a solid lock up and then tighten both adjustment screws tight to be sure it is aligned dead flat to the threaded bar. I unlock it and see if it will lock up again. Sometimes I have to slightly loosen the adjustment a bit to get an solid but consistently tight lock up.
4) I look at the blade spacing to the cut face of the rock after each slice for the slightest hint of a blade cupping either in away from the cut face or tighter to the cut face. The first "solution" is sharpening the blade but if the alignment still is off from what I find "perfect" - I reverse the blade. Between these two solutions I get even cuts for the blade life. I have not had a blade cupped bad enough to need to send out for straightening in probably 4 years since I figured out this seems to cure the first indications of cupping are occurring.
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Who would you send it to to straighten a cuped blades and what is the approximate cost for a 10"?
Jerry
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10" blades aren't that expensive. You could probably get a good blade cheaper than having someone who knows how straighten your old blade. That is if you can find an old timer who still does it.
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It is only cost effective to send in top quality blades at least 18 inches with at least 1/2 their life left.
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Thanks everyone.
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OK, I get it. It was stupid to ask about 10" blades but since our club saws go up to 24" I would still like an answer to the question: who does this?
Jerry
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Puget Sound Saw Service
9823 160th St SE
Puyallup WA 98375
253-845-9629
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Thanks
Jerry
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To see if it is an alignment problem or cupped blade, mount a pencil or pen in the vice so that it just touches the blade behind the sintered section. Manually move the blade forward and see how the point aligns with the blade. A bright light helps. If you can get the light right, you can see if there are gaps between the blade and the pen point.