herb
spending too much on rocks
Member since November 2011
Posts: 442
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Post by herb on Nov 2, 2022 15:00:39 GMT -5
I have a Raytech 10" saw. The clutch started slipping a bit last year and it is only slowly getting worse. I remember seeing posts here saying you could still buy the part for around $100 (I think). I'm not 100% certain the issue is the clutch and not the threaded rod the clutch clamps to, so before I spend the money for a new clutch, I took mine out of the saw to look at it and started wondering if it would be possible to refurbish the existing clutch rather than buying a new one. Here are some pics to show what I am talking about: IMG_9833 by Shiny Objects, on Flickr IMG_9836 by Shiny Objects, on Flickr IMG_9840 by Shiny Objects, on Flickr The threaded rod goes thru the smaller hole. The larger hole is where the guide rod goes thru. The threads look most worn on the right side of the top half and the left side of the bottom half. Measuring the threads on the rod, it is 19 TPI. I inherited a tap set from my dad that has an 18 and a 20 TPI bit but, of course, no 19 TPI bit. I was wondering if it would be feasible to get a 19 TPI bit and put the 2 halves in a clamp like in the 3rd pic and then redo the threads with the 19 TPI bit. I've never tried tapping threads so I have no idea how hard or easy it is to do. Potentially complicating the whole procedure is that the hole appears to not be perfectly round. It is a little shorter than wide as you can kind of see in the 3rd picture. I don't know if it is that way by design or from being worn down. If by design, I guess I could put a thin spacer in between the pieces. It was hard to get an accurate measure with my calipers but it looks like the hole is about .03 inches shorter than wide. Also, because the threads have been worn, I'm thinking I'd have to file off a bit of material where the 2 halves join to make the hole a tiny bit smaller otherwise the tap might not do much of anything. Just thinking about it now, I guess the tap would not really be able to address the thread wear on the left and right sides, just the top and bottom so maybe this whole idea isn't going to work!
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,332
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Post by quartz on Nov 3, 2022 0:16:09 GMT -5
There is no common thread that is 19 TPI, there is a 1/4-20, 1/2-20, 5/8-18, and 9/16-18, and no metric thread {1.33mm pitch} falls into that range either. Start by measuring the diameter of the threaded rod. Likely it is not metric, I would think either 1/2 or 5/8 dia. If you shave the split line you also shave the guide hole diameter, will that work then?
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Post by Peruano on Nov 3, 2022 9:46:44 GMT -5
The threads do not look clean in your photos. This probably means they are not engaged deep enough by the drive rod (as you have already deduced). If this was my machine I would clean the threads, and take tiny bit off of the faces of the two pieces so that the threads of the respective halves better gripped the drive rod. It might not take much and no harm done if this does not solve your problem. I have an old covington saw that just a bit of increased pressure to bring the two halves together is enough to make it work instead of slipping. You may need space between the halves to allow them to tighten just a bit more. JMHO.
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herb
spending too much on rocks
Member since November 2011
Posts: 442
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Post by herb on Nov 3, 2022 16:37:24 GMT -5
There is no common thread that is 19 TPI, there is a 1/4-20, 1/2-20, 5/8-18, and 9/16-18, and no metric thread {1.33mm pitch} falls into that range either. Start by measuring the diameter of the threaded rod. Likely it is not metric, I would think either 1/2 or 5/8 dia. If you shave the split line you also shave the guide hole diameter, will that work then? I took another look at the threads. I don't know how I came up with 19 TPI, it is actually 24 TPI! I must have had a temporary counting impairment! Here is a pic of the rubbing I took of the threaded rod. The short lines are the threads, the longer lines I added to mark every 5th thread, and at the bottom is 1" marked off. IMG_9842 by Shiny Objects, on Flickr The threaded rod is .302 inches wide. The area of the threaded rod that gets the most use is down to .298 inches so that might be part of the problem too. The end of the rod at the back of the saw is not threaded and in .25 inches wide. Not sure what width the tap should be since .302 inches doesn't really line up with any fractional inches. Good point about if I shave the halves of the clutch it also reduces the diameter of the guide rod hole! That shouldn't be a problem because the guide rod actually slides inside a cylinder that runs the length of the carriage and the clutch clamps on to that cylinder, not the guide rod directly.
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AzRockGeek
has rocks in the head
Member since September 2016
Posts: 627
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Post by AzRockGeek on Nov 3, 2022 17:01:58 GMT -5
It is most likely a 5/16-24
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herb
spending too much on rocks
Member since November 2011
Posts: 442
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Post by herb on Nov 3, 2022 17:03:42 GMT -5
The threads do not look clean in your photos. This probably means they are not engaged deep enough by the drive rod (as you have already deduced). If this was my machine I would clean the threads, and take tiny bit off of the faces of the two pieces so that the threads of the respective halves better gripped the drive rod. It might not take much and no harm done if this does not solve your problem. I have an old covington saw that just a bit of increased pressure to bring the two halves together is enough to make it work instead of slipping. You may need space between the halves to allow them to tighten just a bit more. JMHO. I can try cleaning the threads both on the clutch and the threaded rod. But that would be only a temporary fix since nothing stays clean very long in a saw! I was thinking of just shaving down the halves of the clutch a tiny bit but am concerned about the lever shown on the right hand side of the 1st picture. It has the be facing toward the front or toward the back of the saw when you flip it up in order for it to engage and clamp the clutch tight. Just shaving material from the halves would make the clutch looser without screwing down the lever a bit more so it is 180 degrees (or multiple 180 degrees) tighter from where is sits now. That is why I was thinking the threads would need to be re-tapped too because shaving off enough to be able to screw the level down an additional 180 degrees might mean making the hole too small height wise.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,332
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Post by quartz on Nov 3, 2022 22:11:54 GMT -5
If you skin a bit off the split line you could shim the lever and spring to make it work without having to rotate the lever. It looks like replacing the threaded feed rod and a good cleaning of the clutch threads would be a good place to start.
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herb
spending too much on rocks
Member since November 2011
Posts: 442
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Post by herb on Nov 15, 2022 16:24:27 GMT -5
Thought I'd give everyone an update on my clutch refurbishing. It turns out for all the tap bits I inherited from my dad, he didn't have a 5/16-24 bit so I had to wait a few days for one to arrive in the mail. I didn't know how much I should shave off the 2 halves of the clutch, so I first just clamped the 2 halves of the clutch in the vice, ran the tap bit thru, and then inspected the results. I could see a little bit of the threads had been refurbished by the bit but not a lot so I took the clutch halves to some sand 100 grit paper on a flat surface for a bit and then clamped and retapped the clutch. I could see the bottom half of the clutch was getting more refurbished than the top so I just sanding down the top half and retapping until I was happy with the results. The existing hole in the clutch halves is a little wider than tall, so the 5/16 tap could only refurbish about 80% of the threads, from the bottom to most of the way up the sides. When I reassembled the saw, it turned out I had removed enough material that the lever now locks in place exactly 180 degrees from how it did before, so I am just going to leave it like that rather than trying to put a shim in place. I did not replace the feed rod. I couldn't figure out how to remove it. Here is a picture of the front end of the feed rod. There is a set screw on the left side of the coupling which will release the rod from the gear motor. There looks to be a pin of some sort on the right side which I couldn't figure out how to remove. Drive Rod Front by Shiny Objects, on Flickr Here is the feed rod in the back. There is another pin holding the end in place. I tried pushing the pins out but they didn't move and I didn't want to force it. IMG_00Drive Rod Back by Shiny Objects, on Flickr If anyone knows how to remove those pins, I love to hear about it! For now, the saw is back up and running though. The fact that the threaded rod is slightly thinner in the middle where it gets the most wear does not seem to be a problem for the refurbished clutch. Hopefully the saw will continue to feed for a long time, but the slabbing season is over for this year so I'll have to put the saw thru its paces next year.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,332
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Post by quartz on Nov 16, 2022 0:01:10 GMT -5
Years ago the pins were called "roll pins", then they became "spring pins", and now "split pins" only your hardware store will know. They have a light press fit into the respective holes and are driven out with light taps with a hammer and drift punch. Drift punch having a straight end of a diameter the same as the pin and a flat face on the end, or ideally a few thousanths of an inch smaller. If your pins are 1/4 inch in diameter, a 1/4 drift punch is what you want.
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herb
spending too much on rocks
Member since November 2011
Posts: 442
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Post by herb on Nov 16, 2022 0:59:17 GMT -5
Years ago the pins were called "roll pins", then they became "spring pins", and now "split pins" only your hardware store will know. They have a light press fit into the respective holes and are driven out with light taps with a hammer and drift punch. Drift punch having a straight end of a diameter the same as the pin and a flat face on the end, or ideally a few thousanths of an inch smaller. If your pins are 1/4 inch in diameter, a 1/4 drift punch is what you want. Wow! I think I almost learn more new things about tools, hardware, and fasteners from this group than I do about lapidary things! I did try pushing the pin out with a small nail set, but not knowing if that is really how it is supposed to be done, I didn't want to force it. Are they directional? I assume you can tap it from either end? Are the pins reusable, or would I need a new one to put it back together? That pin makes getting a replacement threaded rod more complex since I'd have to drill holes in it for the pins and the hole would have to be pretty close to what the pin diameter is so it doesn't just fall out.
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quartz
Cave Dweller
breakin' rocks in the hot sun
Member since February 2010
Posts: 3,332
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Post by quartz on Nov 16, 2022 23:33:44 GMT -5
Normally if you or someone else in the past hasn't mashed up both ends on a pin they can be reused, and are not directional. The pins come in standard sizes, measuring your picture I'd say yours are 3/16", very common. That is the size the hole should be carefully drilled. the pins are about .010 {ten thousanths of an inch} over size, and the split in the pin allows them to compress a bit to fit into the hole fairly tight. The hole can be marked on the shaft by putting the flanged hub on the shaft where it will be permanently positioned and using a piece of sharpened 3/16 rod, or the same size center punch if you can come up with one and hitting the "punch" to mark the shaft. There are transfer punches made just for this but they come in sets, perhaps someone you know has a set. The end of a pin entering the hole should be chamfered, tapered just a bit, to aid in it starting into the hole. If you get your old ones out and can reuse them at least look at a new one to see the chamfered end. Thought about this today, forgot one thing. If you go ahead with replacing the rod, drill the pin holes with a drill press and the rod in a vise if at all possible. The opportunity to get an on center hole is greatly enhanced. Let the vise do the holding part which allows you better control over the process.
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