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Post by MrP on May 16, 2017 4:16:39 GMT -5
@shotgunner here is a picture of my 20" saw using air for the feed. The rectangle part, middle left on the front, is a set of jaws that open to accept a 1/4" all thread rod that I use to start the feed. I start the feed with the rod to get the blade started into the stone then put the air to the feed.
The air cylinder is just a one way cylinder. There was a PVC cylinder feed by water when I got the saw. The cylinder is 1 1/2".
Simple regulator to limit input air, pressure gauge to know where you are at, valve on right is closed to give cylinder pressure and open to allow feed to be pulled back, center valve to feed pressure to cylinder.
I have cut a 6 X 9 piece of a picture sandstone, that was very hard for sandstone, in under 3 minutes with a perfect cut........................MrP
Just curios , was that saw made in Minneapolis ? Looks like the one I mentioned earlier . Yes I believe it was. It was set up to use water but being water and oil don't mix I changed it to air. I really like the saw..............................MrP |
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Post by MrP on May 16, 2017 4:27:50 GMT -5
On closer examination MrP seems to have a magnum hydro. Can't mistake that vice, have you ever used the built in slab grabber edge? If it's like the one I fought/maintained for the club the side opposite the arbor flexes a lot and makes for lots of saw lines, my fix was to fabricate a piece to bridge the gap and in made a lot better cuts after that. Yes I have used the slab grabber. I think it works fine. When I use the grabber I put a block of wood on the far side of the vice so there is even pressure on the jaws. It has been a great saw. I enjoy the fact that it will cut at the rate the rock will allow, meaning if the rock cut easier it can be a fast cut. Also the blade will not get jammed if the rock is hard to cut because the carriage will just take longer to move. On very hard rock I will turn the pressure up once the blade has started into the rock to help speed the cut..................................MrP |
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Member since January 1970
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Post by Deleted on May 16, 2017 8:10:34 GMT -5
Rockoonz Lee what do you mean about the bounce in pneumatics? What and where is this action? I get compressed air is a spring. I can't visualize how this is detrimental. I would be grateful if you would describe this issue. Thank you Air is very compressible, you can fit a room full unto the tank on a divers back. With oil, on the other hand pressure doesn't change the volume very much. You could use air, but you need something to dampen the action. The Magnum Hydro saw that the club used to have had a regular screw feed with air assist, the screw set the cut rate and the air was there when needed. Never needed it. Why do I need to dampen the action? That is my question. What is the actual issue with pneumatics? |
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Post by wigglinrocks on May 16, 2017 9:29:41 GMT -5
Just curios , was that saw made in Minneapolis ? Looks like the one I mentioned earlier . Yes I believe it was. It was set up to use water but being water and oil don't mix I changed it to air. I really like the saw..............................MrP Thought it looked familiar . A friend has a 24" that he is switching back to air also . I have only seen the saw a few times and can't recall the name on it . Be good if he has the manual for it , I think he bought it new years ago . |
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Post by youp50 on May 16, 2017 13:04:12 GMT -5
Air over fluid dampens action by orifices or spring loaded back pressure valves.
Air pushes on the fluid, fluid flows through the system to a cylinder. Part of the system restricts the flow of fluid. As pressure is applied by the cylinder any uneven load, such as dirty ways or out of round blade will tend to push back against the cylinder. In a pure pneumatic system, this will move the piston backwards, or slow the forward motion. Pressure will build in the cylinder until the restriction is overcome and the piston will surge forward. Only to be stopped or slowed by the resistance to motion and pressure will build. This back and forth pressure surge and motion is what is referred to as the 'springyness' of air.
Water and oil are virtually noncompressible. A pure hydraulic system will push at a force of area of piston times psi of hydraulic system, no reverse, every stroke or rotation of a pump will advance the cylinder, limited by the pressure relief valve.
Air over fluid is a hybrid system using the best of both worlds in certain applications. (Some hydraulic systems use a pre charged accumulator to soften the force) As applied to saw feed, the air pressure applies pressure to the fluid which applies pressure to the piston in the cylinder which applies force to the carriage. If the rock is very hard, the rock is held against the blade at the force set by the pneumatic pressure set by the operator. (Similar to what the clutch does in a screw feed saw) If the carriage has a rough spot that resists the smooth feed pressure will increase to move it. When the carriage moves it is not sprung ahead because there a flow rate reduction devices in the pipe. It will not surge ahead to be resisted to be returned to be surged ahead etc like a pneumatic system. It will not be forced ahead like a hydraulic system, a given advance per pump stroke.
All three systems can be used to feed rock saw carriage. Pneumatic and air over feed at the rate the rock allows. A steady springy type pressure is applied. They are much cheaper to build than a hydraulic system that utilizes pumps, relief valves etc. Hydraulic systems that use city water pressure could be 'softened' by the addition of a water hammer arrestor.
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Post by MrP on May 16, 2017 17:41:19 GMT -5
Yes I believe it was. It was set up to use water but being water and oil don't mix I changed it to air. I really like the saw..............................MrP Thought it looked familiar . A friend has a 24" that he is switching back to air also . I have only seen the saw a few times and can't recall the name on it . Be good if he has the manual for it , I think he bought it new years ago . I bought mine used so have no manual for it and have found very little info on it...............................................MrP |
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Post by rockpickerforever on May 16, 2017 18:32:14 GMT -5
MrP wigglinrocks - just trying to jog your memories. Could it be a saw made by Great Western Lapidary Equipment Co.? The company used to be located in Chula Vista (Southern California), no more than ten miles from here. But pretty sure they went out of business some time ago.
We picked up a saw like that (hydraulic assist) as a project a year ago (it's still waiting....). It was supposedly based on the Great Western design. I also went looking for a manual, no such luck.
Does it look like this? 
I'm still looking. |
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Post by wigglinrocks on May 16, 2017 18:41:21 GMT -5
I'm not sure the name on the saw , I only saw it a few times . I remember it does have a tag on the front of it but that is all I can remember about it . I will get as much info about it as I can when he is back in town next week . Forgot to tag , rockpickerforever |
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Post by MrP on May 16, 2017 19:06:19 GMT -5
MrP wigglinrocks - just trying to jog your memories. Could it be a saw made by Great Western Lapidary Equipment Co.? The company used to be located in Chula Vista (Southern California), no more than ten miles from here. But pretty sure they went out of business some time ago.
We picked up a saw like that (hydraulic assist) as a project a year ago (it's still waiting....). It was supposedly based on the Great Western design. I also went looking for a manual, no such luck.
Does it look like this?
I'm still looking. I talked to an owner of a rock shop that was very knowledgeable who told me it was a Magnum Hydro that was made in the Twin Cities.............MrP |
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Post by Rockoonz on May 16, 2017 22:45:41 GMT -5
Air is very compressible, you can fit a room full unto the tank on a divers back. With oil, on the other hand pressure doesn't change the volume very much. You could use air, but you need something to dampen the action. The Magnum Hydro saw that the club used to have had a regular screw feed with air assist, the screw set the cut rate and the air was there when needed. Never needed it. Why do I need to dampen the action? That is my question. What is the actual issue with pneumatics? explained better than I can the process, results are smooth cuts and efficient operation. Honestly, though, when my non screw feed saw is sold and in someone else's shop I'll be estatic. |
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Post by wigglinrocks on May 23, 2017 23:35:12 GMT -5
@shotgunner , I talked to the guy about the air/water feed saw . Said he has the manual somewhere but is sure it wouldn't give specs or anything about the valves and such on the saw . It is a Magnum Hydro , same as the one MrP posted photos of and explained the system pretty much the same as my friend did . If there is anything else you want me to ask him , just shout . He will be off and running again next week . |
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