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Post by bobby1 on May 17, 2012 21:28:06 GMT -5
I have a HP 18" saw and the threads in the brass jaws that grip the feed shaft have finally worn enough that it is slipping and not driving the rock into the blade. My questions are: 1.Is there a kit to install new threads by modifying the brass jaws? 2. Can I get replacement jaws? 3. What else can I do? Thanks for any help that you can offer. Bob
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Post by deb193redux on May 17, 2012 21:47:03 GMT -5
if the threads are right, you might be able to use one of the pliers type of clutch. Covington sells them as "split pliers" in their catalog. I think it is 13 TPI. (p,55 of 2012 catalog).
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Post by jakesrocks on May 17, 2012 21:47:03 GMT -5
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Post by deb193redux on May 17, 2012 21:53:28 GMT -5
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Post by bobby1 on May 17, 2012 22:01:20 GMT -5
Don, Thanks for the info. I see the parts on their site for $120. I'm going to ask them if I can get just the inserts and I can install them myself. Bob
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Post by jakesrocks on May 17, 2012 22:05:01 GMT -5
Daniel found the right link. $40.00 is a lot better than $120.00
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Post by johnjsgems on May 17, 2012 22:06:17 GMT -5
Make sure they are the same. I heard they changed something on the feed system. Diamond Pacific probably has the parts you need.
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Post by catmandewe on May 18, 2012 8:35:10 GMT -5
The new feed system is not the same as the old one. The original feed system does not have the inserts, it is all one part and the threads are machined into the part. You can buy the $120 part and it is supposed to bolt right on to the old system and the next time you only have to buy the inserts.
Tony
PS- You can also braze new material onto the old part and then recut the threads, but you really need someone who knows what they are doing to make it work.
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keystonecops
freely admits to licking rocks
Member since October 2010
Posts: 957
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Post by keystonecops on May 18, 2012 9:15:34 GMT -5
To back up what Tony said, our rock clubs shop has an 18 HP. If the rails are round, it's probly pre 1960. In keepn ours goin, we discoverd that pre 60 they just used what was layn round the shop. Still good quality, just makes it harder to get parts. We had a member what was a machinest, and he did what Tony said. Brased the gears and remachined it. As many hours as our shop puts on saws, were replacn it with a new HP. At least parts won't be an issue. Later Clyde
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Post by bobby1 on May 21, 2012 11:11:37 GMT -5
Thank you all for your help! Down the road I may have to go for the new jaws with the replacable thread inserts. I rechecked the feed screw threads and found them to be 1/2-20 not 1/2-40. I dug through my tools and found that I had the 1/2-20 tap so I removed the drive rod and rethreaded the jaws. When the jaws are engaged on the feed screw shaft they make contact with each other at the bottom side of the feed screw. I filed this contact point in each jaw down slightly so the jaws would come together in a tighter manner and the tap would engage the threads a little deeper and make better threads. It was about a total 20 minute fix. So far it is working great! Some trivia: I did a few calculations and measurements and found the feed rate of the saw. The feed screw makes 1 revolution every 15 seconds, thus 4 rpm. With the feed screw having 20 threads per inch it takes 5 minutes to move the carriage 1 inch. Bob
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Post by deb193redux on May 21, 2012 11:42:48 GMT -5
Good for you! I have started to say you can't run a saw for any length of time without becoming a bit mechanically minded.
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Post by bobby1 on May 21, 2012 13:28:23 GMT -5
Yes, My background in equipment maintenance helps a lot. I'm on my way now to replace some gears on the club's saws. They get a lot of use because all of our club equipment is in the Modesto Junior College's lapidary and jewelry classrooms. Bob
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Wolfden
fully equipped rock polisher
Member since November 2007
Posts: 1,368
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Post by Wolfden on May 21, 2012 20:14:35 GMT -5
i just used a tap and recut the threads on our 10 inch saw , works as good as new now
Dennis
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rocpup
spending too much on rocks
Pink Limb Iris
Member since March 2011
Posts: 465
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Post by rocpup on May 26, 2012 10:51:56 GMT -5
I have two HP 14" saws both experienced the problem described. I got mine working in two different ways. One would not feed and I tried cutting new threads with a tap. That worked for about three cuts. I filed the stops down to get more a better clamp on the feed rod and again the tap. After failing again I checked the feed rod and found it had worn undersized and the threads very sharp. When the feed put pressure on the cut the feed rod would slip and cut out the clamped thread. I gave up with the threads in the feed clamp and made a clamp by cutting a nut in half and welding it to a spring clamp that now pushes the vise through the cut. After finding the feed screw was the worn out part on the first HP saw I repaired the feed screw on the second. A trip to the hardware store brought back A piece of all thread and two long double nuts. Hacksawed out the feed screw and being careful ground off the threads in the same place as the removed piece. This stops the feed in a long cut or the shut down switch does shutdown the saw. Both repairs work great and Diamond Pacific does not have my gold.
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