rockbottom
starting to spend too much on rocks
Member since August 2008
Posts: 117
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Post by rockbottom on Feb 24, 2009 20:40:43 GMT -5
Chris, it looks good and I bet it will work great.
Bob
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Post by Hard Rock Cafe on Feb 24, 2009 21:59:14 GMT -5
So, you got a working motor?
Looking good!
Chuck
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Feb 25, 2009 0:11:13 GMT -5
Hi Chuck, Well, funny enough, this is the "original" motor I had to begin with, bought it at an auction for 10 bucks, and hoped it worked, never got around to ever firing it up, or even knowing "why" I even bought it until I recently decided to build a lap, then I realized why I was previously driven to buy the motor, it was one of those "meant to be things", funny how that happens! Anyhow, I first planned on using this motor, which is a 1725 RPM motor, single speed, and then it occurred to me that being able to slow down the speed might be an advantage after talking to a few people who mentioned it was a bit fast for polishing things like opals and such, so I bought that 3 speed motor from the surplus store, which turned out to be a dud afterall...lol. I guess I was "mislead" into thinking that this 1725 RPM single speed motor could be "speed controlled" via the blower motor speed controller I bought from that same surplus store, and also I thought I read on here somewhere that someone used one on their home made lap too, I dunno, I'm still not really "sure" what will "happen" to the motor if I were to hook up the speed controller to it, what actual effect would it have on the motor? Anyhow, I fired it up for the first time tonight, I only have some crappy peel and stick carborundum abraisive papers from the surplus store, (stuck onto a 60 grit 7" grinding wheel, lol) they seem to polish for a bit, then fizzle out, (especially after getting wet, even though they are "water sandpaper") exactly what I expected, but had to play with anyhow "just because"...lol. I cut some slabs of a large black tourmaline crystal with the tile saw, then "pre-formed" them with the "side" of the sintered diamond saw blade after cutting them, then attempted to polish them with the flat lap wheel, but like I said, it is a futile effort, and I'm aware I"m skipping a whole lot of steps in grinding, and smoothing before stupidly attempting to "polish" them with only 400 grit carborundum paper. I will get "serious about the actual "use" of the lap once I can either "make" or buy the proper grinding/polshing wheels for it, right now I've just finished concentrating on making the thing actually "work", now I'll concentrate on making it work "well" and "properly" with all the correct abraisive materials ect, and hopefully I'll be able to get some decent results. The next project after this one is confirmed "complete" is a slab/trim saw, a "proper" one Chris
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Feb 25, 2009 0:32:44 GMT -5
Here are a couple of black tourmaline slabs I cut and shaped, and then "partially" polished, which are awaiting the "rest" of the steps to bring them to their full potential as nice shiny slabs I'll probably wire wrap in sterling silver wire If I can do these to this stage with "what I've got", I'm really excited to see what I can really do once I get the "proper" material to work with! Chris
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Post by Hard Rock Cafe on Feb 26, 2009 8:37:05 GMT -5
Congrats and have fun!
Chuck
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Mar 1, 2009 0:36:27 GMT -5
Lamp dimmers have a problem with inductive loads like AC motors. Dimmers essentially work by chopping the AC sine wave and removing or expanding the length between the "chops". Inductors like transformers, and coils in motors create large voltage spikes the current is abruptly changed in them. These spikes can destroy the triac in the dimmer and/or break down the insulation in the motor or coil windings. At low speeds this creates an exorbitant amount of heat in the motor/coil also. The best way to control the speed of induction motors is with a variable-frequency power supply, but they are pricey. If you what a variable speed motor, look for a 120V DC (brushed) motor (think tread mill) and get a www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=43060And you could calibrate the dial with one of these www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=41727Dr Joe .
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Mar 4, 2009 15:14:26 GMT -5
Thanks Dr Joe! I really appreciate your feedback and suggestions! That router speed controller you posted brought up an interesting question (especially since my home made lap is built upon a router table!) which is could one make a flat lap out of a "router", and a router table, rather than a furnace blower motor like most people use. Would it just not have enough "tourque" to get the job done? I wonder if it would be any good to try? What do you think? Chris
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Saskrock
fully equipped rock polisher
Member since October 2007
Posts: 1,852
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Post by Saskrock on Mar 4, 2009 19:35:36 GMT -5
Most routers go about 20000 rpm. I'm not sure if even one with a speed contol on it would go slow enough to be used.
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Mar 8, 2009 18:49:52 GMT -5
Thanks I just bought another motor, it's a 3450 RPM pump motor, it's a 1HP 19A motor, nice and quiet, I'm wondering if that RPM is a suitible RPM for a rock saw? What is the optimal RPM for a rock saw anyhow? I know it seems to be "blade related", as I viewed a "chart" displaying appropriate RPM's for various saw blade sizes, but that didn't really explain much to me. Is there a certain "preferable" RPM for certain materials you are cutting, or for certain types or sizes of blades? Is 3450 RPM too fast? I hope I can use it for the rock/slab/shaping saw I intend on building next! Thanks all! Chris
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Mar 8, 2009 18:50:35 GMT -5
Oh, BTW, it's a "wet" saw I'm building, thought I'd better add that fact
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Post by Hard Rock Cafe on Mar 9, 2009 6:07:50 GMT -5
Chris: 3450 rpm is tile saw speed, twice as fast as you need for a rock saw (broadly speaking; it is blade diameter related).
Do some searching on the web and you'll find recommended speeds. Diamond Pacific's web site is a good start.
Chuck
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Mudshark
fully equipped rock polisher
Diplomacy is the art of saying 'Nice doggie' until you can find a rock. Will Rogers
Member since December 2008
Posts: 1,083
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Post by Mudshark on Mar 9, 2009 17:19:25 GMT -5
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Post by akansan on Mar 11, 2009 9:08:10 GMT -5
With a motor that fast, you'd have to seriously reduce the motor speed through pulleys to get the blade speed down. Most rock saw motors are 1750 - 1775 RPMs, and the pulleys cut down the speed to 600-1000 RPMs. Many of the blades on the market aren't recommended for over 1100 RPMs... and that's a matter of they'll go that "fast" (1100 RPMs), but it's not recommended.
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Mar 17, 2009 16:12:59 GMT -5
Thanks for the tips and info everyone, I really appreciate it! For some reason, I thought that a saw was very much faster than a lap, not sure why. Anyhow, I'll do the belt/pully thing on this saw I'm building as opposed to a direct drive, as it's not likely I'm going to be able to regulate the speed on this motor either, as per the earlier discussion about motor speed control. One question I do have is what "style" of saw to build, there are the types that look like a regular wood cutting table saw (like the tile saw I have), with the blade "resting" in a resivoir of water below, and then there are the ones that look like a "bench grinder" almost, and have water fed from the top on both sides of the blade, and you hold the material to be cut "up to it", so that it makes contact with the bottom of the saw blade. What kind of saw do you have, and what kind of saw is better? Take a look at this "youtube" video showing the latter saw type I described: It looks pretty good for just trimming off the "usable" opal with pretty good precision, and cutting away the potch, but I don't think you could make decent "slabs" with it unless you had some kind of table or attachment below to regulate the thickness as your cutting it to get an even thickness slab. Maybe "both" styles of saw are of use in their "own" way"? What do you think? Which is the better more versatile saw to own? thanks, Chris
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Mar 21, 2009 9:17:21 GMT -5
The one in the video is a true "trim" saw used by experienced cutters. The water supply on the one is all fresh to keep old grit away from your cuttings, it can be used on a "table" type saw too, just drain the water out of the saw quickly and adapt two lines (one on each side of the blade) to spray water on the blade from underneath the table. I'd suggest the "table" style saw for beginners, it's just easier to work with and you get straight edges. You also don't have to worry as much about shaky hands and broken stones. You can do about everything on a table saw, just some cuts are easier on trim saws (mostly pre-carving stuff). If your cutting Opal, stay with the thin blades, as thick (tile) blades can cause vibration in the stone which leads to cracking. Thin blades don't/won't last as long as the others so use judiciously and they can be damaged easily so this is where the steady hand comes in (.006 thin-.012 thick). And keep these just for the Opal, use the tile saw for jasper etc. Stay away from segmented blades for everything but the roughest cutting of "rocks" & side carving, and never with Opal (vibrations). And as a point of order, you don't " trimming off the "usable" opal" just the "potch" (which can have two meanings too). (Your Opal buddy would get a kick out of that). For ref. here's another blade saw speeds www.gravescompany.com/blade.htmDr Joe .
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cooknet
starting to spend too much on rocks
Member since February 2009
Posts: 169
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Post by cooknet on Apr 10, 2009 2:05:42 GMT -5
Thanks for the info Dr Joe, I appreciate it. I just purchased another motor, it's a "gear head motor" which is 557RPM's. Would this be a more suitible motor for a rock saw? Perhaps I could make a saw using this motor as a "direct drive" type rather than a "pully type"? Providing that 557RPM is ok for a rock saw that is? I just figured it was a better speed, because all the previous higher RPM's I mentioned were recommended that I "step down" the speed with a pully system. I figure belts and pullies are high maitenance, and will eventually need the belt replaced, tightened ect, is that true? Am i better off with a "direct drive" system? This gearhead motor was a special OEM design, I contacted Bodine Electric, the manufacturer, and they happily gave me the specs and wireing diagram, real nice guys, the torque rating is 4.0Nm, the gear ratio is 3:23:1, it is 6.1Amps, so I get the feeling it is a fairly beefy motor, good enough for the job? What do you think? Thanks all! Chris
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drjo
fully equipped rock polisher
Honduran Opal & DIY Nut
Member since May 2008
Posts: 1,581
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Post by drjo on Apr 10, 2009 6:21:04 GMT -5
Is that the output shaft speed? High speeds (3000rpm) are only for the small (4") saws. 6" and bigger drop down to 1725-1020 rpm and lower. Pulleys give you the option to change speeds for different types of stone and cutting rates. They are relatively maintenance free (kept clean and tensioned properly). I'm guessing most here change a belt once a year just for something to do. Tile saw blades can handle the higher rpms, just not the lapidary ones. If you used a pulley system on this motor, you could easily drive a 14" blade. Direct drive is fine, but you have the bulk of the motor to deal with (it gets in the way of the rock passing by it). Creative design work needed here. Dr Joe .
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Post by akansan on Apr 10, 2009 9:13:52 GMT -5
You might have to use pulleys to speed the machine up. Lapidary saw blades normally run between 600 - 1100 RPMs, if I remember correctly...
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