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Post by phil on Jan 26, 2013 16:47:47 GMT -5
OK. A friend of mine cleaned out the overdue 24 inch highland park saw at work. The crud was about 4 inches deep, and it hadn't been cleaned in years. Everything worked fine before he shut it down and shoveled out the gunk. Blade was not removed. Gunk was cleaned off the rails, drive threads, etc. Not much more was done. Now, when he puts in a rock to cut, it cuts into the rock about 1/2 inch and stops. The blade is still spinning, the drive thread is still rotating (outside gear is going, can't see inside actually). We tried putting in a small 4 inch piece of petrified wood to dress the blade, got 1/2 inch. So, the blade seems to be cutting, but the sled stops moving. I checked for bare spots on the drive thread, found none. Silicone greased it and the rails just in case. Looked at the spring pliers and they don't look stripped, I can see good thread both sides, but can't see the whole thing. Spring that hold the clamp closed on the drive thread is strong, takes effort to operate. Released the clamps and the sled moves freely back and forth, can't feel any hang-ups or anything. But we can let the saw run and the sled goes no further. Also tried a larger piece of alabaster, same result with this softer stone. Blade is not glazed, I can feel sharp edges at all the notches and feel diamond on the "cutting edge" and diamond on the sides. Will try dressing the blade but as it cuts the first 1/2 inch, I don't think it's the blade. It seems that something is keeping the trolley from moving past 1/2 inch into the rock. The cut is full of oil and not dry. But when the clamp is not engaged, the trolley moves freely the whole length of the saw. Only thing he changed is that he removed the gunk and replaced the old oil with fresh mineral oil and replaced the old oily belt. He has the oil about 1/2 inch up the blade, but not covering the notches. I watched the unit turned on, and all pulleys and etc ate moving, there is no slippage in the drive train that I can see. The drive gear doesn't stop rotating, sound like the blade is rotating, besides, he didn't remove it loosen the blade at all. Everything else is as it was. Only thing I can think of at this stage is to cover the blade with a box next week to contain the slinging oil, turn it on, and watching the innards to see what happens when it hits the area where it comes to a halt. It's an older Hp, I'd guess about 50's or 60's era, but it was working very well before he drained and cleaned..... so... has anyone run across this before and can anyone help me figure this out for him. He knows how to use the saw, but has zero mechanical ability. It's gotta be something simple, I just can't see it yet. Thanks!!! Phil
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Steve
has rocks in the head
Member since June 2005
Posts: 506
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Post by Steve on Jan 26, 2013 16:58:48 GMT -5
I have a 16 inch Royal that currently has the same problem. I was told that the clamp onto the drive thread has most likely become worn. The fix is to remove the clamps and grind them a bit until they again get a good hold onto the drive thread. Haven't had the time to do this yet, but my friend has had to do this several times for old saws. Just waiting until we both have a free afternoon on the same day.
Then there's always the unhelpful answer - put the gunk back.
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Post by Peruano on Jan 27, 2013 10:09:53 GMT -5
You probably have the right answer from Steve above, but its not obvious to me in my quick read that you have done the true null friction run. IE engage the clamp and let the saw run past the stop point with no rock contacting the blade. Then you will have the absolute proof that it is the worn worm drive or something blocking the trajectory besides the rock (not present in this case). If it stops does it stop in the same position everytime. If it stops with no rock, what does it do if you advance the sled 0.5" and then reengage? I do like Steve's solution and will store that one for the future. Tom
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Post by johnjsgems on Jan 27, 2013 10:52:37 GMT -5
Good idea on the running without a rock. If it stops while cutting only I'm guessing the long drive belt is slipping or else blade is slipping. The blade could be slipping after cleaning. By the way, you can't dress a blade by cutting petrified wood. You need something abrasive like an old SC wheel, fire brick, or dressing stick. If it is an old style notched rim blade try reversing the blade. I used "paving stones" on my 24". They are the 2" thick toppers for cinder block walls.
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Post by snowdog on Jan 27, 2013 11:05:13 GMT -5
I have a 18" lewaco that does that to me too -- usually I find it's the clamp for the drive ( even tho it looks like good threads the edges are worn and being spring loaded , they will slip over the threaded rod ) mine are reversible so I turn them over or sometimes put a small vise grip pliers on the clamp so it can't push apart too much --then it cuts like it's supposed too -- other times I check the belt tension as it may be slipping a bit when the friction get to be more, and have also dressed the blade ------ one of these three things should get you back to running ;D -------- my next thing is to have a new set of clamps made or mill a little off top/bottom and run a new tap to recut the threads in the old clamps there has been one or two agates that are so hard I have given up on them but when I got a new blade and tried them again , the saw went on thu them ( think the old blade was warped just enough that it would bind up once it got 1/2 way thu the rock )
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Post by phil on Jan 27, 2013 13:16:27 GMT -5
Thanks everyone. Yeah, I've already told him we need to run a trial empty and see what happens. The odd part is that it ran fine when all gunked up but now stops at the same spot regardless of which rock. I need to ask him if he may have bumped the blade when he was shoveling, if he bent it a wee bit, it could be binding when it gets that far into the blade. Belt is brand new, and the pulleys have been cleaned of all rubber detrius, oil, etc. So no slippage there. I've watched it run (lid closed) and nothing is slipping or stopping that can be seen from the outside. Don't really want to drain all that new oil to be able to run it dry, will try fabricating a cardboard cover for the blade so I can watch everything else with lid open and running. Will recommend he reverse the blade (it's been used for years and never reversed). And also will take an old broken 220 grit carbide wheel to cut thru a couple times. So, tomorrow will go over and do a run empty, check blade for warpage, and take a tooth brush to the threads in the clamp so I can see if they're worn (possible but ??, as it worked fine before). The clamp spring's strength we already checked, it's not weakened at all. When engaged, we can't force the carriage to move. If the clamp was worn, I'd think we could make it jump a few threads? Will also check blade run out and dress it. So, anything I've missed or forgotten? I think everything above should have it covered? Thanks again! Phil
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Post by snowdog on Jan 27, 2013 15:40:45 GMT -5
Phil -- I can't "push" mine forward either--- think it's more like just the pointed edges are rounded off on the clamps and when the friction gets too much they open just enough for the threaded rod to jump over the rounded part to the next thread -- like drilling thu a knot in a piece of wood ( you only need a 1/2# of pressure until you get to the knot , then you sit there and spin in the same spot or you apply a little more pressure to get thu) I put the vise grips toward the back on the clamp so it can still open but is a little harder to spread it -- I've tried putting more tension on the spring that holds them together but that doesn't seem to make the difference I need --- put on a new 303 blade and I don't need the vise grips for awhile --got sharp little diamonds chewing out the rock then ;D
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Post by Rockoonz on Jan 28, 2013 0:24:39 GMT -5
Are you sure that the nut that holds the blade on wasn't inadvertently loosened, causing the blade to stop turning when it gets so far into the rock? It would look like it saw still spinning from the outside.
Lee
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Post by Woodyrock on Jan 28, 2013 2:53:24 GMT -5
One other thing you can check is the bronze feed nuts (the plier like things) . They can LOOK fine, but still be worn to the point the carriage will not move forward into a cut. Unbolt the fixed one, and check to see if the half threaded hole is actually round, and not elliptical. If it is not round, or half round but, elliptical they are worn beyond use, and need to re placed. Diamond Pacific probably still has some, but the new Highland Park company ones are better. They have replaceable nut inserts. A good machinist could do a braze build up, and rebore/rethread the old ones but that could be more expensive than replacing them. My 20in HP was doing this,and the fix was replacement. If you search, you can find before, and after photographs of the worn/new nuts. Woody
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Post by phil on Jan 28, 2013 11:13:34 GMT -5
Thanks! Will check and let you know what the fix was if we can find it.
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Post by phil on Jan 29, 2013 20:06:08 GMT -5
OK as far as t he saw fix. Today we started checking the #1 suspected culprit, the clamp. It was cruddy and full of mud. First I started cleaning it off so I could remove it and check the threads, but they didn't have the correct tools. I took a trimmed toothbrush, and moving the threaded rod to first one side then the other, cleaned the clamps threads well. Thought I'd to remove just the clamp, but they didn't have the tools needed.... 1/2 the sockets in their set were missing. Upward and onward. Looked at it some more and decided if we removed the 2 bolts holding the clamp, we could take off the whole assembly easier. While my partner was looking for the right socket for them (1/2 inch) I started cleaning them. To my surprise, I was able to unscrew them with my fingers.... Hmmmm. So, I started to remove them. But wait..... what if that was the problem??? So I tightened them, and nope, they need to be somewhat loose, just not too loose. Tightened, we couldn't operate the spring clamp mechanism at all. So I backed them a wee bit and we turned it on to see if the sled would movewhile empty. Nope. It moved to the same spot and quit with no load. OK. no choice, gotta remove them and take them home to tap new threads. Then I remembered a suggestion by someone to clamp the clamp closed so it can't open and etc. We gingerly applied a clamp just tight enough to prevent the clamps from opening once closed. Voila, the sled moved past the stall spot. OK, so all we've done so far is a little more cleaning and some bolt tightening....Hmmmmm. So.... my friend is so far behind in production (saw's been down for 2 weeks), I said if he wanted to try and get caught up a wee bit, as long as he didn't overtighten that clamp, we could see if it'd cut rock, then take it fully apart later to fully fix it. He really wanted to try and make some $$ by a little cutting, so we took a piece of soft petrified wood, clamped it in the vise and were going to clamp the bottom when I said, lets try it without the hand clamp. We may have gotten lucky and forced it to clean, cut, reset itself, and besides, I'm curious, So we ran it that way. It cut all the way past the stall spot, and cut the whole rock. yea! making sure it wasn't a fluke, we tried a bigger piece of rock, from the list of things they needed cut. Yea! It cut all the way through! By this time, it has been a very long day (lapidary at the senior center all morning, then repairs here.... I said it was Miler time, and as I'm not on a time clock, was done for the day. He agreed, and will try using the saw tomorrow to do some production, and see what happens etc. So, we still need to remove the clamp and tap it to cut new threads, but at least we now have the problem square in our sights and will do a long lasting fix in the near future. Thanks everyone, your experience and suggestions made this a lot easier! Phil
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The Dad_Ohs
fully equipped rock polisher
Take me to your Labradorite!!
Member since September 2012
Posts: 1,860
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Post by The Dad_Ohs on Jan 29, 2013 20:26:04 GMT -5
I had the same problem with my 18 inch Lortone, the solution was the lever that released the sled to slide back and forth. There is a set screw on the handle to set where the handle sits when it is released and the set screw allowed the handle to slip over just enough to keep the threads from engaging properly when in the closed position. Sooooooo, after crawling over everything else on the saw, we snuck an Allen Wrench in under the vise, loosened the set screw, moved the handle away from the rest spot a little farther than it was, tightened it and have not had a problem since!!
I would check that before anything else.... just loosen the screw and move the handle about 1/4 - 1/2 inch over from where it is now then tighten it down good and give it a try!!
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riverbendlapidary
fully equipped rock polisher
Member since September 2006
Posts: 1,058
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Post by riverbendlapidary on Jan 29, 2013 23:14:33 GMT -5
try a new spring first
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Post by snowdog on Jan 30, 2013 9:20:02 GMT -5
;Dsounds like you now see what is happening !--- will prob be okay for awhile, until it gets some more crud in the threads or he puts a bigger , harder rock in there and the blade pressure is equal to the clamp/spring pressure and will stall again if you do clamp it shut with a vise grip just be careful that it doesn't stall the blade and make the belt/motor burn up ( that's why I put it at the back end of the clamp ,so it can still open ,but does put just a little more pressure on it) I've tried tightening the spring more but that doesn't seem to give me the pressure I need
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Post by phil on Jan 30, 2013 12:53:34 GMT -5
Thanks. will keep an eye on everything. he's going to try and use it today.
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