Using Gravity to Feed a Saw in Cutting
| chad | Post by chad on Jun 30, 2012 10:07:03 GMT -5Looking to pick up a 10". Had a conversation with an agate cutter who adamantly advocated gravity feed over power feed for cutting precision slices out of high end agates. A lot of what he said made sense as I don't believe the feed speed is adjustable on most power feed saws (though this is a guess that may not be based on reality). I love the idea Lee posted in another thread about letting the weight drop into a bucket of water near the end to avoid the saw nubs. This just convinces me more that the gravity feed will provide more control and cleaner cuts with less waste. I've seen an ad somewhere for Covington saws that have a sliding table that feeds into the blade under the rock, which seems like a good idea.... But I can't find that again so not sure of the model number. Also seems like a good idea. Are any particular gravity feed saws better than others for any particular reason? If not I'll be keeping my eye open for a clean HP or one of those covvies if I can find one. I've let 3 10" saws slip through my fingers because I didn't think they were what I needed at the time, but now I need to find the right one. Will be running a thin blade and need clean gentle cuts. Any thoughts/suggestions on models to look for? |
| LarryS SoCal desert rats Member since August 2010 | Post by LarryS on Jun 30, 2012 10:29:31 GMT -5I was having problems cutting hard jasp-ag with my 10" Covington saw and fabricated a gravity system for it. Come to find out the problem was with Johnson Brother's Lube Cool, which is total crap. Experimented with RV anti freeze & Borax. Ended up with Kingsley North's Gem Lube which is awesome stuff. Water soluble, biodegradable and mixes 10/1. I use 303C .050 and 303P .060 blades which cut cleanly with no saw marks. These are solid blades and no wobble like the thinner .040 blades. I've cut hundreds of slabs using the power feed since switching over to Gem Lube and never had an issue. Covington's power feed pulls 1" in 8 minutes. |
| Last Edit: Jun 30, 2012 10:30:40 GMT -5 by LarryS |
| jakesrocks RIP Don Woodward AKA jakesrocks Member since April 2010 | Post by jakesrocks on Jun 30, 2012 10:38:27 GMT -5I agree mostly with Larry. However, with a gravity feed, you have more control over feed speed simply by using lighter weights to slow it down. I've had very few problems with the power feed on my vintage 10" covington. However I have heard some complaints about their newer saws. Some of the older large saws used an adjustable hydraulic feed, but I've never heard of this type of feed on the smaller saws. |
| Don --- USN Retired |
| 3rdrockfromthefun | Post by 3rdrockfromthefun on Jun 30, 2012 10:39:20 GMT -5I currently use a 10" tile saw w/a barranca 303C blade. Not long ago I cut some agates up to 6" long using 'body weight feed', lol. I did the cuts at 1" depth passes - surprisingly they came out incredibly beautiful. What that tells me, and my experience with cutting others rocks the same way and having felt the saw's response, is that gravity feed seems like a really good idea for smooth clean cuts. As with my body weight feeding, I should think gravity feed gives the rock and the blade more control over how fast the cut goes (even agates have vugs and inclusions) and that seems to make a big difference. There's that or getting an auto-feed that snails it - this would work best but you'd want it to go slow if you're cutting thick agate (like 7 to 10 minutes per inch - varies some depending on blade, motor speed, agate etc) to get the smoothest cut and fewest chips and nubs. Also be sure to use a blade with fine cutting grit (a 303C is medium I think and though there's minor chipping it's smooth enough grit to polish hard agate as it goes through). My 21 cents and some things to consider... |
| 3rdrockfromthefun | Post by 3rdrockfromthefun on Jun 30, 2012 10:45:17 GMT -5Larry - I use a .04 303C - no wobble problems at all unless I accidentally run it dry. Maybe with oils and lubes that's different - can't say, I'm on a water budget. Anyway I LOVE the super thin .04 - like so much I want to marry it, heh heh... |
| paulshiroma Psalm 145:1 Member since March 2011 | Post by paulshiroma on Jun 30, 2012 11:48:48 GMT -5My setup is almost identical to LarryS's. I did a "ghetto-mod" and rigged a gravity feed for it and used a small 1/2 quart bucket at the end so I can vary the amount of weight. Only difference here is that I use mineral oil for the coolant. I do occassionally get saw nubs if I'm not careful. |
| chad | Post by chad on Jun 30, 2012 12:53:35 GMT -5I only use 303 or 301 blades so that's not a problem. Just looking to fine tune the feed speed on a PRN basis. I LOVE the tip about the water bucket. Now to just settle on/find a saw I like. I'd really like to find some more info about the table-feed covingtons but I'm not having luck figuring out a model number. Might need to write them as its not in their catalog either. |
| Bikerrandy Say what?? Member since September 2005 | Post by Bikerrandy on Jun 30, 2012 13:15:29 GMT -5I converted my 16 inch Covington from power feed to gravity feed.... I'll NEVER use power feed again!!! |
| geoff | Post by geoff on Jun 30, 2012 18:29:18 GMT -5Hmm. This is all relevent to my interests. Been researching the exact same ten inch. |
| LarryS SoCal desert rats Member since August 2010 | Post by LarryS on Jun 30, 2012 18:48:28 GMT -5 |
| Last Edit: Jun 30, 2012 19:05:55 GMT -5 by LarryS |
| Rockoonz Member since August 2009 | Post by Rockoonz on Jun 30, 2012 23:21:42 GMT -5My 18 inch ROC hydraulic saw is by far my best saw but I use my screw feed saws a lot more simply because they shut themselves off when they're done. I only use the hydraulic when I'm in the shop with it. Lee |
| "If history could teach us anything, it would be that private property is inextricably linked with civilization." |
| johnjsgems Member since August 2007 | Post by johnjsgems on Jun 30, 2012 23:27:02 GMT -5I don't know of any "sliding table Covington saws". Covington 10" is available with weight feed. I hand cut a lot of slabs on 10" saws with .032" blades but would not recommend anything thinner than .040" on power feed or gravity feed. A rigid blade has less tendency to deflect. No matter how you cut always manually push the blade against the rock and observe blade hits square and does not deflect to either side. I move the cross feed back or forward until blade hits a square spot (even if I get a slab a little too thick or thin). Once you check that, engage the clutch and start the feed. |
| jspencer Member since March 2011 | Post by jspencer on Jun 30, 2012 23:37:04 GMT -5I also ghetto engineered a gravity feed for my 14" saw using items from my garage and some nylon coated cable from Home Depot at about 30 cents a foot. I hung a paint bucket and used diving weights from my diving weight belt. I made a landing pad of foam rubber to ease the bucket thru the crucial point of the cut. I get way less nubs (many times none) than almost any autofeed cuts I have seen. |
| QuailRiver Member since May 2008 | Post by QuailRiver on Jul 1, 2012 18:20:05 GMT -5Rock's 10" slab saw is weight driven and has a sliding table. |
| chad | Post by chad on Jul 1, 2012 19:18:38 GMT -5Like the idea of a gravity saw factory made for power option from the start... But without looking I still feel safe guessing the cost would be prohibitive. DP = $$$ Will check out rocks. Thanks for the info! Edit: looks like that rock's saw is my next one! The vise is like the one on my Covington 16" which is the best vise I've used. It seems like the sliding table would be ideal in terms of keeping the feed perfectly straight too for slicing thin stuff like iris. Thanks again! |
| Last Edit: Jul 1, 2012 19:21:53 GMT -5 by chad |
| johnjsgems Member since August 2007 | Post by johnjsgems on Jul 1, 2012 20:39:37 GMT -5Not to nitpick but Star Diamond was bought by MK/Barranca not DP. DP bought Frantom and HP (HP from Contempo who bought it from MK when HP went under). |
| QuailRiver Member since May 2008 | Post by QuailRiver on Jul 1, 2012 23:19:21 GMT -5My mistake John. I meant Beacon Star rather than Star Diamond. |
| johnjsgems Member since August 2007 | Post by johnjsgems on Jul 2, 2012 7:44:44 GMT -5I forgive you. The history of the many companies that flourished in the 60's and 70's and then died is pretty interesting and confusing. Some of them sold off divisions to different companies before going under or selling out completely. Both of my old Frantom 10" saws had the weight feed pulleys and were tough little saws. |
| chad | Post by chad on Jul 2, 2012 8:40:26 GMT -5Does anyone have any experience with that rock's 10"? It has the perfect feature set I'm looking for. Hoping the build quality is up to snuff. Also there's a site called kreigh lapidary or something with some lapidary mfr histories. Interesting site all around. Find via google |
Source: https://forum.rocktumblinghobby.com/thread/53484/gravity-power-feed-10
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