snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Apr 29, 2013 20:01:50 GMT -5
I've had this HP saw cutting for four years now,no problems.The other day,went out to check on it and there was no progress on the cut.Ihad cut a bunch of slag glass and figured the blade was glazed over,cut a brick and it started working again.Now its doing the same thing. My question is,what is happening when the power feed keeps turning,and the blade is not cutting? Do the clamps have a feature to spread them out when this happens?To avoid stripping out the allthread rod or the threads on the clamps?Got me puzzled,know some of you have had this problem I would think.No damage to the threads anywhere I can see. I just went out and it cut a brick just fine.
snuffy
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,558
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Post by jamesp on Apr 29, 2013 20:13:23 GMT -5
The Covington has a slip clutch if you wanna call it that.The worm gear is allowed to spin and the lead screw can be stopped for what ever reason.In other words,the worm gear is rotating and the allthread shaft is not turning.On the cov you tighten the gland nut to compress the leather washers that serve as the slip clutch to put more torque from worm gear to allthread.HP may be way different design. Looking at the Highland that Don rebuilt the worm gear is on front of saw.Take cover off.Worm gear may be missing teeth or pinion is worn out.I slid the pinion down the shaft a bit and picked up some fresh threads on it to get more use.
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,487
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Post by Sabre52 on Apr 29, 2013 20:19:34 GMT -5
Snuffy: I had this happen a lot with my old 20" saw. Way it was explained to me is the blade edge becomes too rounded ( should be square). Since the top of the rounded part gets deeper into the stone than the edges, the blade eventually binds in the cut and stops. I used to send my blades to Barranca for reforming for like 50 bucks and it was great but they no longer do that. I know some folks hammer form the edge so it's square again but I've never tried that.
If your blade is still spinning but making no progress, then something is wrong with your worm gear as it cannot advance the vice properly without either having the blade cut or bind if it's working right. Saws with clutches like the Covington will simply have the power feed screw drive stop if the blade encounters too much resistance....Mel
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Post by Bikerrandy on Apr 29, 2013 20:19:36 GMT -5
I always had the same problem with the screw-feed on my Covington. The threads inside the nut on the clamp would wear out. It got so annoying that I stopped using the saw for a year or two. I finally converted it to gravity feed (cable, lever and weights) and I've never had another problem!!
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Post by roy on Apr 30, 2013 8:59:31 GMT -5
on my hilandpark the spring got weak wouldnt pull the two arms together tight enough it would get to the the rock and start to cut the quite moving forward changed the tention spring and solved the problem
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snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Apr 30, 2013 9:15:40 GMT -5
on my hilandpark the spring got weak wouldnt pull the two arms together tight enough it would get to the the rock and start to cut the quite moving forward changed the tention spring and solved the problem[/quote Thanks Roy,I had wondered about that too.Seems to have good tension on it,but maybe just not enough! This saw is only 40-50 years old,cant understand having a problem with it this early in its life. snuffy
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riverbendlapidary
fully equipped rock polisher
Member since September 2006
Posts: 1,058
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Post by riverbendlapidary on Apr 30, 2013 12:16:33 GMT -5
probably need to re-tap the threads on the split clutch. It's easy to do yourself, just need the right tap and a vise and some vise-grips.
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Post by phil on Apr 30, 2013 15:30:08 GMT -5
The HP 24 inch my friend uses at work did the same thing. I loosened the two bolts that hold the clamp arms, allowed them to "reset" while clamped then re tightened the bolts. Also took a toothbrush, cut the bristles down to about 1/8th inch, and used it to clean the threads inside the clamp. They do get clogged up if you don't change your oil till it's 100 weight sludge... also took a large "c clamp and used it to hold the clamp arms shut for about 1 inch of travel to help clean out the thread. The saw has worked like a champ ever since. hope this made sense and helps!
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snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Apr 30, 2013 15:49:59 GMT -5
That makes sense Phil.It would seem the problem is either the spring or the threads in the clamps,as you said.At least I have a spare saw to use until I figure this one out.
Thanks for all the replies everyone! snuffy
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Post by phil on Apr 30, 2013 23:09:20 GMT -5
If I can find it, I can forward you the HP manual.... Just let me know if you want it and where to send it.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,558
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Post by jamesp on May 1, 2013 7:57:05 GMT -5
The old stuff was built so well.It is good.
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on May 11, 2013 15:42:48 GMT -5
As I understand , parts for the old HP saws are available from the company importing the new Highland Park machines from China.
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Post by Peruano on May 11, 2013 20:37:54 GMT -5
While the problem may be resistance, i.e. something causing the drive threads to slip; I'd check to make sure that the sled will move forward through the entire trajectory when there is no rock to be cut. If not then its definately a feed drive problem (split nut, or the drive shaft , etc.), but if the sled moves with no resistance and not with a rock in place then you can start looking at blade issues. Again I'd try a small softer rock (i.e. minimal resistance to cut and compare it with something harder (if its a blade problem, the soft rock should cut and the agate might constipate the system. Maybe some of this will help diagnose the problem. Good luck. Tom
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