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Post by Dredger89 on May 20, 2010 19:19:11 GMT 12
Just wanted to know if you all use them, they seem to be common place on dredges these days! In the USA at least! Can not remember seeing one fitted on any dredge operating in Victoria Australia prior to 1990. I fitted the keene supplied one to a T80 compressor and the mounting bolts shattered on the first 6 hour run, never been a fan of the T80, getting the belt tension correct and the pathetic small mounting bolts is virtually impossible. As a recreational dredger i have killed 4 T80s in 23 years, with fairly minimal use. I think i will bin the T80 i have. Keene released a new model compressor KCA, purchased one of those, mainly due to the strong looking mounting feet, attempted to fit supplied snorkel? what can i say? Mexican engineering. Nothing fits? Don't know who designed it or put the bits together? After purchasing correct fittings it fell to pieces and floated down the river within 6 hours. I took my pump and compressors to a friend that is very well qualified in engineering, he feels that the Keene P180s i have do not allow correct clearance for V belt pulley to supply drive for compressor. He could not believe that people would trust such inadequate engineering for Divers supply air! I did co own a 6 inch precision dredge in Canada a few years back it was fitted with the Gast 263 and a well engineered snorkel. Kind of keen to purchase one of them, only drawback is the substantial weight increase. I have always thought hot exhaust gases would rise! Placing a snorkel at an elevated position puts the intake in a toxic gas cloud. Rod
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Post by 2dredge on May 21, 2010 2:15:42 GMT 12
I fitted the keene supplied one to a T80 compressor and the mounting bolts shattered on the first 6 hour run, never been a fan of the T80, getting the belt tension correct and the pathetic small mounting bolts is virtually impossible.Change the mounting system; bolt the compressor to a separate plate permanently using bolts that are a perfect fit (not to short) with locktite thread lock, this is a must and use the plate to adjust the tension. In the past 28 years I have never had a t80 fail in any way. Or with a bit of thought hint use a hinged plate and its self adjusting. It takes me just 2 seconds to flip the belt on or of and 10 seconds to fit the compressor. When time is important I hate stuffing around with fiddley bolts. Another problem I occasionally see is running the compressor at to high a speed because of the wrong choice of pulleys and the air pressure wound up to max resulting in broken con rods and bearing failure. Got to agree though they are a bit weak but treat them carefully and---For 20 years I had a brand new T80 still in the box unused and not needed so I sold it. Still got a big breather and don’t bother with the 263 to save lugging the extra weight around. I took my pump and compressors to a friend that is very well qualified in engineering, he feels that the Keene P180s i have do not allow correct clearance for V belt pulley to supply drive for compressor. ?? Never seen this problem, got the right pulley? Fitted quite a few of them. He could not believe that people would trust such inadequate engineering for Divers supply air! They were adapted for diving and not really designed for this, I did hear that (unconfirmed) that is why they were stopped being sold in Australia because they were not approved for diving so giving rise to liability problems. As to the snorkel can’t help you there as I have only got a home made one out of PVC tube and that has survived a couple of seasons use but haven’t had the chance to give it a work out myself. Placing a snorkel at an elevated position puts the intake in a toxic gas cloud. If I remember correct the most dangerous part of the exhaust fumes is the Carbon monoxide; it is a heavy gas and sinks. Dr.edger
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Post by Dredger89 on May 21, 2010 19:41:33 GMT 12
The pulley is supplied form Keene! Correct according to there specs, even used there supplied V Belt. The main issue i feel is the limited adjustment between too tight or too loose. Too tight destroyes the bearings and too loose the belt bounce will start rubbing in the cast lugs of the pump back plate or cause slipping of the belt. I have compared the Keene P180 to the Proline equivalent. The proline pump is far superior in quality and clearance. A member of this forum now sells them! Allan from Naseby, (snuffy). The snorkel issues are due to the engine vibration and lever factors amplify this, i am quite surprised high tensile bolts clean snapped in half! I have often used a 12 volt hookah system and a little Honda Generator, it is way more reliable but a bit of extra gear to cart in. Of all the T80s i have had best life would have been around 100 hours, the 1st one. Got about 50 on the second, 30 on the 3rd. Number 4 has only done 10 hours. I wish i had purchased an Eldorado big breather when they were on the market back in 1980s. Another issue i have had with the T80s is significant internal corrosion, not sure what caused this? Aluminum oxide could be of concern if breathed in over many hours of use. A filter may resolve this issue. Rod
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Post by 2dredge on May 22, 2010 0:08:41 GMT 12
Gee you have had a bad run with those compressors, my first T80 I got around 1982 and used it on four different dredges before selling it fitted to a 5” that I no longer used. Never a problem; so what is the difference to between the two? Got to think back, first thing I did was to get rid of the Keene mounting plate because of the excessive time and very fiddley job of fitting it up and it was unnecessary extra weight. To do this the pump was mounted direct on to the motor using a design simular to Jessies which worked well and very quick to fit. Next would be the choice of belts, the best I found was an internal ribbed belt, the ones with the deep groves moulded on the inside of the belt and not quite as wide as the old industrial ‘A’ section. The reason for this is they are a lot more flexible, lighter, less drag hence less power loss and give a better grip; less tension is also needed to tighten them. By using these types of belts on car power steering and air con they solved a lot of problems like noise, vibration slipping and wear. Now the Pulleys; I have always used off the shelf aftermarket ones, they have got a nice large off set boss that is easy to machine to fit any shaft, this must be the difference as because of the offset on the pulley it has got enough clearance. The engine pulley was about 2” in dia, max 2.5” and the compressor 6” got to check this out in case I am wrong. To cure the vibration resonating up the snorkel isolate it; try using a flexible coupling between the snorkel and compressor, for ideas look at the flexible concertina drain tube on a washing machine. Last always use a filter, the rubber diaphragms disintegrate over time, more so with age, one dredger that I know could not get back in the water for several years possible due to breathing in rubber particles, he was quit ill with the effects. As to the corrosion problems can’t help you much there except that it is most likely occurring in down time and storage in damp conditions, as I doubt that it happens when in use because the heat generated will drive off any moisture. Dr.edger
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Post by boaraxa on May 22, 2010 14:57:44 GMT 12
hi iv got 1 of those new KAC1 compressors it goes pretty good the best thing about it is the cooler air its no were as warm and dry as the t80 though im not shure how much more grunt it has over the t80 as it came supplied with air for 2 but i had a m8 come out with me 1 day ina farely deep hole "maybe 10-12 foot,ish"and yep didnt do the job not enuf air but haveing said that thers a few leaks in the hose at the join,s so il have to get some plumbers tape and fix it up and give it another go.one thing im undecided on is the big vents in the sides wilst it helps to cool the air when it rains it can just go straight on in! the other thing i like over the t80 is were the snorkel goes straight into the top of the KAC1 and attaches on a decent mount at the top not like the t80 that has the snorkel vibrating on the side with a wee near usless bracket that keene supply.... regards phill.
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Post by 2dredge on May 22, 2010 17:35:30 GMT 12
All this talk about snorkels and their problems got me thinking and the best thing to do is get rid of them; the alternative is to use a flexible hose and I found three just looking round the house; the first was the drain hose on the washing machine, 1inch ID next is the suction hose on the vacuum cleaner @ 1.25 inch ID and finally pool hose at 1.5 inches ID. Or any other ones you can find. Plug one end into the compressor and hook the other end up anywhere on a pole. So much more simple, NO tools, vibration or breakages anymore. It's worth a try, from now on it looks like what I will be doing, another problem solved for the better. Dr.edger.
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Post by Dredger89 on May 23, 2010 23:22:27 GMT 12
I think i will be devoting Winter to designing something better than the Keene base plate. I want to be able to fit and align the compressor real fast and easy! Have been thinking flexible hose for the snorkel, could probably be run out on mounting ropes putting it further out of harmful vapors! Did notice one time when dredging had a blockage, had to get pole ramming down flare and jet, the air was real still and stream in a deep kind of gully, gorge nearly choked on me exhaust fumes! So i guess a snorkel of some sorts is better for safety! Going of the dive tables your taking in more air deeper you go, pollution is going to increase along with additional air consumption.
Rod
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Post by RKC on May 27, 2010 14:12:18 GMT 12
G'day,
If I remember correctly there are a number of posts about dredging compressors, in threads going back as far as the previous forum on MSN, , and over the last few days I have been trying to find them ... however I still can't get the Proboards or Google search feature to work. Next chance I get I'll go through the old threads manually to see what I can find (I'm in Australia at present so I don't have my own computer ... which is slowing me down). I noticed today in the admin section (only accessible by myself) that there have been numerous searches done by "unregistered" for the word "compressor" and if they are having the same poor results I have experienced then they would have not got any results except for the posts in this thread.
Its a real shame there is no decent workable search on Proboards as in every other respect Probards works exceptionally well and I am very pleased I chose Proboards after the old MSN forum closed.
Regards, Rob (RKC)
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Post by RKC on May 27, 2010 15:59:46 GMT 12
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Post by RKC on May 29, 2010 19:53:10 GMT 12
G'day cobungragold, Like you I don't remember seeing any snorkels on dredges in Victoria during the "good ole days" ... the 1980s! Its not hard to imagine that if anyone had turned up on Big River, or the Goulburn, in those days, with a snorkel, they would have probably got a roasting from the serious dredgers. I've never used one myself and would not ... except maybe if I was dredging in a small stream enclosed by vegetation on all sides. And I can't recall too many instances where I have dredged in an enclosed area ... just this one on the Arrow river ( tinyurl.com/2827xw5 ). Snorkels seem to be mostly used in North American rivers (Americans probably like them as they can double as somewhere to hang their flags from . While I personally consider the use of a snorkel on a compressor unnecessary in most dredging situations, I would use a filter on the airline. My experience with the Thomas T80 compressors is that they are subject to severe internal corrosion of the cast aluminum and we all know about the possible long-term effects on health by breathing in aluminum dust particles. We even knew about this health hazard as far back as the "good ole days" and most serious dredgers on Big river (Victoria) back then used filters. The Thomas compressors used by the professional Big River dredgers in the 1980s would regularly fail. But back then the Thomas brand was the only compressor readily available to us (and the only compressor we were aware of, except for the Tuffey aka Eldorado's Big Breather). Out of necessity they had to be regularly maintained and would simply be replaced when they inevitably failed beyond repair. By far the best base plate for mounting a T80 compressor is sold by Keene ( tinyurl.com/238u7dp ). I bought one back in the 80s and used it on this dredge ( tinyurl.com/24roq7u ) and it worked brilliantly. If you could get one in Australia it may solve the problems you have experienced with mounting the Thomas compressor (if you still want to persist with Thomas compressors). As Dr.edger mentioned above, the surest way to destroy a Thomas T80 compressor is to run it too fast. Just another reason to use a large motor on a dredge rather than the motors that come as standard on nearly all recreational dredges, which have to be run at near full reves just to get enough suction. If you have a large motor with HP to spare, then the motor can be run at reduced revs. And this has many advantages, such as reducing noise ... and additionally, the compressor will last longer as it will run slower. More reasons why dredgers who are serious should use Production dredges rather than minimalist recreational dredges, even if it means more weight and the overall size of the dredge is increased. Recreational dredgers are always going to experience continual mechanical problems such as the ones you experienced with your compressor. Recreational dredges are compromises, through and through! But recreational dredgers will still only purchase recreational dredges as they buy to price and most recreationalists put their dredges to so little use the design problems that continually arise are not the major problem they would be to a professional dredger. A professional can't afford down time as he must run his dredges for 6 to 8 hours a day and have the dredge available ready to use at any time during the season when weather conditions allow dredging. The "correct clearance for V belt pulley to supply drive for compressor" is shown here ( img.photobucket.com/albums/v521/NZGOLD/Equipment/NZGOLD022.jpg ) on a Jessie pump ( img.photobucket.com/albums/v521/NZGOLD/Equipment/NZGOLD021.jpg ). Regards, Rob (RKC)
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Post by Dredger89 on Oct 9, 2010 22:19:34 GMT 12
Just found out something i did not know before about Thomas T80s. There is two models, The grey one is a heavy duty model & the blue one is a lighter duty model. I think this explains why some people like them & others do not. Some people get 20 years out of them while others curse the hell out of them. Rod
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Post by fudnz on Oct 28, 2010 7:46:01 GMT 12
Hi Rod, and Rob, interesting reading on the Thomas air compressors... both of my Keene dredges were fitted with the blue Thomas compressors. Both of them gave me trouble with the bearings in them. Another problem with them was the way they were mounted just the proper pain to try and adjust. I ended up using a Braemar link belt to make the adjustment a bit easier. This has been successful on my six-inch dredge over the last few years.
Proline dredges, use the grey Thomas compressor and the base plate mounting is different from that of Keene. Instead of having an angled bracket setting up off the base plate Proline use the same flat base plate with slotted holes making to a very easy adjustment and good locking down. Rod, I had a spare base plate here I did not know that you are actually having a problem as I could've sent one of these over to you to try. Proline have standardized their base plates and now three of them do the job for the whole range of their dredges. Another thing that Proline do because they run the grey model Thomas is use a slightly bigger driving pulley that speeds up the compressor slightly but to well within their limits even when the motor is flat out. I will have a few of these base plates on hand when the new lot of gear arrives from the states early November. I am bringing in a four-inch and a 5 inch dredge short of motors. I will be fitting my own motors that I import from China to the Proline pumps to try to keep the cost back a bit. Interesting, the new Honda motors, the 2.5, 4 and 5.5 HP are now produced in Thailand, while the 6.5 , 8, 9 , 11, 13, 16hp's are mainly built for Honda in China. Must be a sign of the times, I found this out when making an inquiry from my supplier to see if he could search out original Honda for me. No problem was the answer I can get them but they will cost a lot more than our own. You have to pay for the name he said.
Rod, if you wanted a picture of the base plates that are Proline produced send me an e-mail to snuffy@es.co.nz
I'll set the 5 inch dredge up and get it running and it is at this stage that I might downsize to it and sell my six-inch twin 9 hp under and over Keene. Might be something to do with my getting near 70 :-) Time will tell.
Snorkels, I threw mine away years ago when I got the first one fitted to a 5 inch dredge -- boaraxa did ask me about snorkels when he was making inquiries about Proline dredges I told him then that I did not think they were a good thing to have above a motor that was throwing hot air up in the sky. One thing I do have to watch now is that the heat exchanges that I have fitted to my Keene don't throw out a hell of a lot of hot air as most of it is being used to eat the water for my suit. But as long as I am aware of this and the wind is not blowing back towards the compressor from the motor I am happy. Most times my dredging is done in pretty much open areas.
Take care guys and happy dredging -- Allan (fudnz) Naseby. 03 -- 444 -- 9292
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Post by Dredger89 on Oct 28, 2010 18:29:32 GMT 12
This weekend is being devoted to manufacturing & designing a better bracket system. Pictures will be put up for anyone who is interested in improving there own dredge. ;D
Rod
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Post by Dredger89 on Oct 30, 2010 20:52:55 GMT 12
What a Day! Work is progressing well on the new sliding bracket mount system. Initially i am doing my 5" Dredge powered by a 7.0hp Subaru engine. The Dredge is built by Alan Trees, of "Gold Dredge Builders Warehouse". I purchased the dredge minus hoses and engine, i had assumed it was coming without a hookah compressor but it arrived with a silver Thomas T80? I have found out the silver one is a more heavy duty than the blue one. The engine & compressor plate that came with the dredge is similar to the Keene set up, slotted holes etc. A very talented friend with very well equipped workshop is assisting with the design! The workshop motto is: If its worth doing its worth overdoing! ;D Also keep it simple applies! We have used Aluminum flat bar. The bracket now is a 3 piece unit, a base with milled slots & mounting feet. We then milled up two smaller brackets to match the milled slots, one each for the engine & compressor. The compressor bracket has slots milled in to adjust for loose & tighten. It was quite tricky as working from a centre line the compressor slots were a little offset? I will post pics to explain set up. At the days end we assembled what we have, adjusting the belt tension is now a breeze. It could be performed with cold wet hands and minimal tools. A major issue with the keene style slotted plates is its a struggle to get both pulleys aligned due to play in holes to bolt size. The system i have perfected does away with this as it is now spot on! The T80 is mounted to its base bracket so the small mounting bolts are not taking the strain of the belt drive. ;D I took my camera today but did not take any pics as we were on a roll with production! It was interesting seeing the milling machine mill the slots & drill holes. It is fitted with Digital readout for X & Y table movement plus tool depth. The resolution of display was down to 0.001mm, one button press the display converts to imperial inches. Also drilling a series of holes means they are all evenly spaced. The mount holes for T80s are 3 & 3/8 " apart, we drilled and they lined up perfect. It would not be possible to do this task accurately with out the milling machine. As it turns out the bracket system is not to much heavier than original set up. The last part of the job will be an adjustment screw system. The best thing about the workshop is the river is out the back, great spot for testing any modifications. Today Heavy rain caused the level to rise. Rod
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Post by RKC on Nov 1, 2010 14:34:16 GMT 12
G'day fudnz,
Its interesting to learn that Honda motors are now made in Thailand and China ... its actually something I've wondered about. I'll have to try and find out where Honda motorbikes are now made. My present preference for a dredge motor is Briggs and Straton. The current model B&S motors are much improved on what they have been in the past and they have proved themselves in PNG on the National Gold dredges. However, they are probably too expensive for most Kiwi dredgers.
I would not personally employ any Thomas compressor on a dredge unless I absolutely had to. And if I had to use one, I would be sure to have a spare always on hand so there would not be any downtime if it should fail in the field. Back in the 80s the Thomas compressors were the only viable dredge (dry) compressors available to dredgers, but these days there are a number of alternative compressor models available (listed above) to chose from. The new KEENE KAC1 compressors looks particularly interesting ... I'd be interested to hear some feedback from anyone who has used one for an amount of time.
Anyone making one of the larger production dredges, such as 6-inch and bigger, would probably be best to use a GAST compressor. Although they are expensive to purchase these compressors will probably last much longer than any of the dredge compressors available these days.
I vaguely remember seeing a photo of one of your heat exchangers (HWS) on an Internet forum many years ago that, if I remember correctly, was made from stainless steel. If you would like to post a photo of your heat exchanger on the forum, please feel free to do so.
Regards, Rob (RKC)
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