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Discussion in 'METROLOGY - MEASURE, SETUP & FIT' started by Bob Korves, Jun 12, 2017.
WOW! Just wow!
I watched that yesterday at work. Amazing.
Hey Bob, you have a surface grinder. Are you taking orders?
Not yet, but I am looking closely at 7" 1A1 diamond grinding wheels, 150 grit, and at the Norton combination stones. For those who do not use stones for cleaning up burs, it really works well and the original geometry and surface can be kept mostly intact when used correctly. Robin's methods kick that idea up by several more notches, and I will definitely be going there...
I'm probably going to get slammed! I have a dedicated granite surface plate that I use for such purposes. When it starts to look ugly and or not work as it should, I will go buy another plate. But I have been using the current plate for about 20 years now and it still works great. Yes, I know a surface plate is not a deburring station, but it’s my shop and I have more than one plate…Dave
I have been using very fine hard stones, albeit much smaller, for as long as I remember for the same kind of things Robin was demonstrating. Something I picked up from my mentor many moons ago.
It never occurred to me the stones may not be flat or to use a second stone to keep the surfaces of the stones clean.
Seriously wish I had room for a surface grinder. Grrrr...
Which stones are you looking at?
Stones are on order. Should have them Saturday on my Amazon Prime. Now, all I have to do is mix up some coolant for the surface grinder and mount my diamond wheel and I'll be ready to go!
I am looking at the same stones Robin was using, Norton 61463685560. That was the 6 x 2 x 1".
Like this https://www.zoro.com/norton-combina...81&gclid=CPn2_8WxvtQCFQlVfgodQFMFcw&gclsrc=ds
but still looking for a better price.
Robin also showed the same stones in 8 x 2 x 1" and 4 x 1-3/4 x 5/8".
I thought they were $500/pair?
If you buy them ready to use from me they are. That is at my $1.00/hr labor rate. My labor includes procrastination time...
Very good video, but in all reality does the average hobby machinist need to get the stones that flat, I think its overkill. yor just removing burs
I recently bought some Japanese water stones for knife sharpening, 200 grit, 4000 grit and 6000 grit. there were around $60:00 each.
I also bought a flattening stone for $50:00 and a cleaning stone for $30:00 does everything I want and does a darn good job sharpening knives.
I also have a sharpening steel, but it's ceramic at 8000 grit
I'm not sure how many hobby machinists even think about stoning precision surfaces. From the outset it seems like a bad idea ,and could be if you used "any stone". Once you understand that with the correct stone and technique you won't damage the precision surface. Robin did a good job of explaining that in his video.
There are lots a precision mating surfaces that stack up in our work holding that benefit from good machine practices.
I know I have gotten some sideways looks when I take a stone to the spindle nose and back of a chuck or a tool with a tapered shank. As we move around our not-so-hard big clunky chucks and vises or have a bunch of tools with precision ground shanks floating around together in a drawer they get bumped and nicked and need to tuned up occasionally.
I'd bet money I'm not the only person who has drilled a hole too close to a parallel and turned that nice crisp ground edge into a saw tooth. With a proper stone and technique that can be cleaned up without further damaging the parallel.
Did Robin mention in the video what diamond wheel he used on surface grinder? If he did I missed it.
7" O.D., 150 grit, 1-1/4" bore, 1/2" wide, 1/8" thick resin bonded media, 100% concentration. I just ordered one of that description from Shars, p/n 505-2233. $81.00 plus freight from Shars, $91.00 and free shipping on eBay. I went with the eBay order, saved about five bucks. I also ordered the stones today, Norton 6 x 2 x 1" combination aluminum oxide, part number 05108568. $15.99 each.
Every mounting hole I see is for 1-1/4". My grinder takes 3/4"
OK, but isn’t it a simple lathe operation to make a bushing reducer. Or, am I missing something? My little Sanford has a 1/2” spindle. All my wheels have 1 1/4” holes. I just made some bushings. And the arbor flange and washer still catch the sides of the wheels. All is good now. Note; make sure you use a paper washer on each side of the wheel when mounting…Dave
1-1/4" with a 3" spindle taper per foot is a very common size for surface grinder wheel adapters (hubs). What kind of grinder are you contemplating using? This project requires an accurate grinder and flat and true chuck, a smooth running and tight spindle without runout, and a wheel with near zero runout (well dressed.) Not sure yet, but it might require coolant as well. If you do not have all that, you will not achieve what is needed to make quite flat stones with quite flat abrasive surfaces with a large surface area so they will work correctly. Make sure you understand what Robin is achieving in the video. It is incredibly cool, but not easy to achieve.
Got a lathe? Make a bushing.
This may be a silly question. Robin rubs his stones back and forth. Would it not be better to rub them in a figure 8 motion? I was wondering if that would help keep them flat.
Ask Robin the answer to that as a comment to his video. He is so far ahead of me that I would not presume to know the answer. You can bet there is a well considered answer. Robin does not do things "just because." Robin is the most talented machinist I have seen yet, not that I am any kind of an expert. Seriously, ask him, and then report back with what he says...
(I got my two stones yesterday and the diamond wheel for my surface grinder today. Ready to get started...)
Bob, I picked up a set of stones made by GWHOLE, made in China. I was quite impressed on how flat they are right out the box. Not sure about the quality of the stone. When I rub them together, they seem to wear down producing powdery superfine grit. I also have a set of Norton stones as Robin uses in his video coming sometime next week. When I get them, I'll see how flat they are coming out of the box. Then I'll set up and SG all four stones and report my results. Ken
Thanks, Ken. I will be trying it, too. I do not have flood coolant on my surface grinder and I wonder how the diamond grit in the resin bond will do against the stones. I do have a mister setup I could use, or perhaps a plastic pump bottle like for various household cleaners. It might be good to find a pump bottle that can send a real stream, I will look around in my stuff for one. We want to flatten the grains, not tear them out. Heat could cause problems with the grit coming apart from the bond, or with damaging the resin bond on the wheel. Wisdom?
I have a flood coolant system set up but haven't used it yet. I've been dry grinding since day one. The only real problem I see using dry grinding on these stones is the dust it will create. A mister I think will be your best bet keeping the dust down. I think from our standpoint, we will see very little difference between dry and wet grinding of stones. As for clogging up the diamond grinding wheel, I don't think that will be a problem. I don't think using a mister will clog up the grinding wheel either. Should help keep it from clogging up. Ken
As much as I have used diamond wheels to grind carbide, I've never had a problem with the wheel clogging up on a 150 or 220 grit wheel. Now, the 800 grit wheel I have on the old slow speed grinder for sharpening my scrapers, it seems to load up a little, but a wipe from a rag when it's not running usually all it needs to remove spent grit. Now, the few Chinese diamond wheels I've bought, I have mixed results in using them. They don't seem to cut as good as a good old Norton diamond wheel will. Just my opinion!
I loved the video and ordered an offshore diamond wheel and 2 - 4" X 1" stones to try out. I intend to dry grind the stones and see what happens. They say that I'll get them some time mid-to-late Jul. Fingers crossed!
Let's all keep in the loop on this. I have the diamond wheel and the stones, but it has been blazing hot here (108 F forecast today, 110 F tomorrow) and I have some other things I need to get done as well. I am quite interested if dry grinding will work for this. My plan at this point is to use my mister unit. I wonder if cutting oil or shortening might work?
I don't think you want to try that on a diamond wheel.
Just as hot here if you figure in the humidity, just have too many irons in the fire here to play right now. Maybe this weekend before I can play.
My friend Bert only dry grinds with his diamond wheels. I know about toxicity of carbide, etc, but from the wheel longevity of the grinding wheel, his have lasted 30 years.
Thanks, Dabbler. I am not in my comfort zone with these resin bond wheels. I have a 4" cup wheel with resin bond diamonds, 600 grit, and it works good dry, but I only use it at very slow RPM for sharpening carbide scraper blades. Robin was taking some eye opening plunge cuts in his video, and I don't think I am ready for any of that yet, don't want to destroy the wheel or throw a stone. Speaking of which, are there other work holding ideas beyond the feather board tools Robin was using? Is just blocking them in well with steel near the stone thickness good enough?
I plan to make a steel fixture for grinding my 4 X 1 stones, consisting of a channel that is wide enough for the stones plus 2 layers of notepad cardboard. There will be set screws along one side to put even force on the stone and a plate at the end for support. I'll pregrind the bottom so the stone will be held flat (or on 3 points as necessary). When I'm done the jig I'll post a photo or 2.
I believe Bert's diamond stones are vitrified bond, I'll check with him on this.
My diamond stones are coming as resin bond (cheap, less than 20$ CDN each). I know that you can't put much pressure or generate much heat or the resin is toast. I'll be plunge cutting as well, but in tenths with very slow hand wheel feeding, and waits at the end of each pass. I won't be using coolant, even though I have the setup. I don't intend to clean up 100% of the faces, so if there's a little around the edge not flat, NBD. I want to get to the end result for this test with as little fuss as possible.... About the jig - for a very experienced grinder hand, I'm sure the finger boards are very safe. I'm absolute novice to SG, and rely on Bert for my info. For this test I'm much more comfortable making the jig. Maybe one day I'll make finger boards and try it. -- When I've got a lot more miles on the grinder.
I worry if the parts are just blocked in, then there is too little pressure on the stone to keep it from vibrating and moving. just my $.02.