robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 9:50:41 GMT -5
Any advantage to adding a counter weight in the front I wonder or would that just be give and take? Thought it might offer a more controlled type deal not sure. Also seen other things like stretch cords, fish scales etc.
I don't have any exp using gravity on large saws and would like to hear how you do it etc. I can add powerfeeds that's not an issue. I have a vise set up that has very little drag because of the design and I thought it might be a good candidate because there would be very little resistance otherwise in other words a free rolling vise.
Big difference between that setup and the standard 2 rods or 1 rod and metal on metal. It's like pulling a car with all 4 wheels inflated vs. pulling a car with a flat tire.
No pics at the moment just giving you the general idea and would welcome any comments to consider once I start messing around with it here pretty soon.
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Deleted
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Post by Deleted on Oct 1, 2013 11:16:34 GMT -5
I had thought it might be beneficial to add a air spring (think screen door) to the front. Not so much to push, but to act as a bounce absorber.
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Post by catmandewe on Oct 1, 2013 11:40:58 GMT -5
Great Western saws are gravity feed with a pneumatic shock absorber for when the cut breaks through. I have an 18" and a 24", both work great and the speed of your cut is dependent on the size and hardness of the material being cut not on the speed of the auto feed.
Tony
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Post by jakesrocks on Oct 1, 2013 11:41:57 GMT -5
I've used both power and weight feeds. Presently using power feeds, but weight feed has its advantages. You can vary the weight to suit the material you're cutting. Softer materials like obsidian can take more weight than agate or other hard materials.
Most weights that I've seen or used were nothing but a cable from the vise running over a pulley at the rear of the saw, with weight suspended from the cable. For the weights, I've always used deep sea fishing weights. They can be purchased in 1 pound increments from a pound up to several pounds.
A third feed option that has been used on saws is hydraulic. A hydraulic cylinder which has adjustable pressure pushes the vise into the blade. I've never owned or used one of these, but I seem to remember a couple of our members having this sort of feed. Maybe they'll see this thread and offer more info.
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jamesp
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Post by jamesp on Oct 1, 2013 12:08:11 GMT -5
Gravity sure sounds logical.
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robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 12:50:33 GMT -5
Gravity sure sounds logical. Steve at Covington did tell me one time that gravity never failed him. LOL. Other advantages......less broken crap to worry about. And.........trying to stay away from hydraulic altogether. Works great, just don't want to deal with it at the present time. As far as the Great Western saws they also have easily moveable vises which is why the gravity works well. I only seen one time and was wondering why a hydraulic saw would need a weight feed now I know it's just a shock absorber. Question is does it offer counter resistance, not just a device for the end of the cut, which would fall in line with Shotguners idea? I'll just play around with it later this week or next.
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Post by catmandewe on Oct 1, 2013 13:00:26 GMT -5
Gravity sure sounds logical. Steve at Covington did tell me one time that gravity never failed him. LOL. Other advantages......less broken crap to worry about. And.........trying to stay away from hydraulic altogether. Works great, just don't want to deal with it at the present time. As far as the Great Western saws they also have easily moveable vises which is why the gravity works well. I only seen one time and was wondering why a hydraulic saw would need a weight feed now I know it's just a shock absorber. Question is does it offer counter resistance, not just a device for the end of the cut, which would fall in line with Shotguners idea? I'll just play around with it later this week or next. It has an adjustable rate, you can set it to resist the cut or to just be a shock absorber, which ever you prefer. Tony
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robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 13:06:18 GMT -5
Having problem with the link but just read placing the weight in water or oil will reduce the cutting force and reduce end of cut breakouts. That makes a lot of sense. I would assume doesn't work as well as the plunger but it might work good and this might be something of interests to others here to try and see. I certainly didn't know about it.
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Post by johnjsgems on Oct 1, 2013 13:07:48 GMT -5
Great Western uses a heavy weight and the adjustable cylinder as a brake. You can delete the cylinder by varying the amount of weight. Most common thing used is a plastic jug of water or sand. Lower into a bucket of water helps slow down at end of cut. Slow cuts are always better for smooth cuts and longer blade life.
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robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 13:14:20 GMT -5
Here's a saw I haven't seen yet. What a bargain lol: www.diamondpacific.net/swing_arm_slab_saws.htmlAnd apparently someone is thinking just like me because I thought of this design a long time ago so it was kinda odd seeing it. Not much of a hydraulics guy so didn't do it and I was going to use some kind of brake system. Except mine was going to be a 36" saw and the rock would go in the very bottom so you didn't have to lift it up, etc.
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Post by johnjsgems on Oct 1, 2013 13:30:21 GMT -5
That price doesn't include a blade either. I think a drop saw would be easier to build than a traditional slab saw. You would need some way to slow down the drop rate. China HP is making a 36" drop saw now.
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jamesp
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Post by jamesp on Oct 1, 2013 14:18:59 GMT -5
I thought about a lot of those designs. I have a 72 x 36 x 24 inch deep cabinet of 1/8 steel. It is laid over and i welded 5 gallon sumps in each end to manage sludge.2 inch drains on each. It is on 8 inch castors. I was going to do it like a Highland Park or Covington except lose the screw drive and rig a steel cable on a pulley up in the air so it would have 3-4 feet of travel(ie long drop). And build a simple stout carriage and simple rails to run it on. It would weigh 1000 pounds easy. So. Use red iron for most of it. Target was a 30 inch blade.
I have the container finished. I one day may build a big saw. To me bigger is easier. Little 18 covington is fairly complicated. Lots of moving parts and lite.
The big box is strong enough to be structural so welding directly to it would be fine.
But my thoughts was to have a horizontal carriage with a steel cable and weight to pull it along. Fixed blade. Just feels safer than drop arrangement.
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Deleted
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Post by Deleted on Oct 1, 2013 14:25:21 GMT -5
in any saw the vice to hold the stone is the (forgive me) "keystone" of the deal. Without a good solid vice. Nothing else works.
Jim are you utilizing a pulley/cable/weight to pull the carriage? 3-4 feet of travel is very long and requires the weight have a similar 3-4 foot drop. Thatsa tall saw! I guess you would build a platform around it and a gantry/hoist system above for positioning giant rocks. Hell, you could have the lid on rails so it will simply roll back and out of the way.
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Post by Hard Rock Cafe on Oct 1, 2013 15:30:43 GMT -5
I love my 18" Great Western; it's no HP, but it's a fine, compact hobbyist saw. As others have said, it uses a hydraulic cylinder to adjust the feed rate. I have a lot of weight on mine and adjust the pressure (feed rate) with the hydraulics. I've never tried the shock absorber approach with it; might have to give that a try. I usually don't have tearout at the end of a cut unless the rock is not very solid.
Chuck
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robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 17:09:56 GMT -5
in any saw the vice to hold the stone is the (forgive me) "keystone" of the deal. Without a good solid vice. Nothing else works. Jim are you utilizing a pulley/cable/weight to pull the carriage? 3-4 feet of travel is very long and requires the weight have a similar 3-4 foot drop. Thatsa tall saw! I guess you would build a platform around it and a gantry/hoist system above for positioning giant rocks. Hell, you could have the lid on rails so it will simply roll back and out of the way. You just put the weight feed rope under the first pulley and then have a pulley mounted higher and loop it over the top of that to your desired distance. Much easier than building a platform or digging a hole. The hoist system is not a bad idea,neither is a rolling hood however a hood that opens along the long end of the saw is a possibility so it's not sticking up in the air so far. Maybe even a 2 pc type set up, fold down in front etc etc there's endless possibilities.
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robsrockshop
has rocks in the head
Member since August 2012
Posts: 715
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Post by robsrockshop on Oct 1, 2013 17:15:31 GMT -5
I thought about a lot of those designs. I have a 72 x 36 x 24 inch deep cabinet of 1/8 steel. It is laid over and i welded 5 gallon sumps in each end to manage sludge.2 inch drains on each. It is on 8 inch castors. I was going to do it like a Highland Park or Covington except lose the screw drive and rig a steel cable on a pulley up in the air so it would have 3-4 feet of travel(ie long drop). And build a simple stout carriage and simple rails to run it on. It would weigh 1000 pounds easy. So. Use red iron for most of it. Target was a 30 inch blade. I have the container finished. I one day may build a big saw. To me bigger is easier. Little 18 covington is fairly complicated. Lots of moving parts and lite. The big box is strong enough to be structural so welding directly to it would be fine. But my thoughts was to have a horizontal carriage with a steel cable and weight to pull it along. Fixed blade. Just feels safer than drop arrangement. I doubt I would ever actually build that because I also think it's not as safe and would just be a lot of headache. It's just an idea I kicked around in my head being someone that likes to build things. I couldn't really think of any advantage to it.
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jamesp
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Post by jamesp on Oct 1, 2013 17:33:05 GMT -5
I got started on that box cause it was sitting around destined for scrap. Never know. It sits in the boneyard in case.
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quartz
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Post by quartz on Oct 1, 2013 23:31:22 GMT -5
I did a repair on a rock saw that had the pump and cylinder feed system. Owner said it worked well for a long time, but over the years, the pump-cylinder oil reservoir had accumulated some grit and it ate the pump, and, after fixing that part, I found the cylinder seal was leaking by too. The hydraulic system wasn't isolated well enough from the coolant side. Not a cheap repair. My opinion, not a good design. I've run a couple metal cutting bandsaws with a needle valve on a cylinder to meter the rate of drop, they work great. The cylinder refills via suction on a one way valve when the saw is raised for the next cut, manual lift.
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jamesp
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Post by jamesp on Oct 2, 2013 8:06:25 GMT -5
Tumbling slurry and sludge from the saw is best avoided by particle/foreign oil sensitive mechanical systems.
The saw oil would also concern me.
I think hydraulics is over kill. Old mechanical systems are so bulletproof and simple.
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Deleted
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Post by Deleted on Oct 2, 2013 13:17:20 GMT -5
hydraulics are pretty simple.
Switch, Pump, pressure regulator, hoses, ram. Done.
We have two 24" hydraulic feed saws at school. They claim that they have been repair free for over 15 years. The only working part of the system that seems cutting coolant is the ram shaft as it extends. There is an additional "wiper" rubber gasket with tight hole mounted on the ram body over the shaft to keep rock snot from getting back into the ram. I am sure it aint perfect,but 15 years seems pretty good.
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