I was always taught that you need to engage the mag when testing for level. There's fluctuations between the layers on the surface that can only be found when the chuck is engaged. e.g. magnetic pinpoints and surface pulling. Also, I was taught that you should engage the chuck for 48 hours before grinding, this allows the chuck to settle with it engaged so you get better repeatability. Just something my shop instructor always "ground" into us :)
Oh, interesting. If we're being pedantic, and I think we are, I should also turn the spindle on and let it run for a while to warm up and stabilize, and I shouldn't be stopping it between setups.
32 years precision grinding and i have never checked a mag chuck like that. Now put it on that sine plate, bolt it down, and grind it again. Im sorry for making fun, almost like you just started grinding a few months ago, hehe. I am really enjoying the videos. Please forgive me if i go through your video collection and give you the new apprentice treatment.
That 50-millionth you’re seeing is likely from the amount you’re wasting off of your wheel as it makes its way across the chuck. You can try taking lighter cuts to minimize that, or clocking the chuck 90 degrees between grinds. It’s a dance. Great vid!
Very good job especially for your experience level. About 80% of the life time grind hands I know could not do what you did. Someone commented that you used the diamond dresser wrong but he is wrong. You used it the correct way. If it was rotated 180 degrees into the wheel you would have put a flat on the point and ruined it. Mag chucks are hard to get flat. You have many more variables to overcome. One thing to consider changing is your roughing method. It generates a lot more heat than just coming across it with about .05 step over verses .4. You can take huge deaths of cuts with less than .05 step over and keep the cooler than taking big step overs. I don't do a true step over but just keep the Z axis moving while traversing in the X but it would be close to a .05 or less step over. Also, you don't have to worry about the wheel grabbing the part and throwing it off the table as much. This method work great for light mag work as well. Again great job, I am impressed.
Larger stepovers distribute wear better on the grinding wheel, plus maintain thickness of work from one side to the other (2/3 wheel width). This was the practice when I was using grinding machines. Plus 1 for the diamond, agree with engaging the magnet. I once dressed the wheel too hard, lost the diamond (melt the braze) and told to fish it out of the coolant tank. More to make the point, I think. Surprising, I found it, sitting on the slurry.
@@BillDavies-ej6ye Don't need to worry about the wear in roughing cuts, the heat build up is the real enemy. You true the wheel up with a redress before the finishing cuts. I grind under fifty Millionths all the time with this method on both small and large parts.
Thank you for the nice shoutout at about 5:00 ! I also bought one of these squaring chucks on eBay. I found the bottom bulging significantly, and it cleaned up with a full grind. I'll go finish watching now. 😁
I wish that I could offer some useful insights, but alas, I can only offer praise to you for the process that you ran through while restoring this magnetic chuck. As always, I have thoroughly enjoyed watching your travel through the process of making something better out of its history. Keep up the great work. Your humble admirer, Mark.
we rarely step over the whole wheel width . Most of the time we used lighter cuts ,takes longer but theres a crap load of heat being put in the metal. Alot of the time we left the wheel on all through the project , even through set ups , it's pretty much standard practice in tool and die shops the spindle and column heat up and settle in. in fact it was considered kinda rude to shut it off if you knew some one else was going in right after you. variable mag. chucks are super nice when grinding for flat.
Thanks for the tips. Next time I'm doing something serious, I'll let it run in for a while. That's kind of hard to do when shooting a RU-vid video though, due to the background noise and the comment safety police. :)
I opened some tools my dad had that were NEVER used. He took them out, repacked and put on a shelf for use later. They looked very much like that chuck. Stained, rust, etc. We live in 4 season weather...lots of moisture abound...so it can happen fast...less than 5 years.
James, As an observation, I see alternate conventional and climb grinding. A suggestion from an old guy; for precision work only conventional cut. When climbing the swarf must go up into the wheel prior to being expelled by centrifugal force plus greater contact area for the wheel adding unnecessary heat, not an ideal situation; also the wheels bonds are stressed from two directions. I was taught ( in the early 1970's) by a master toolmaker to only conventional cut! Another thing I see is the grinder being turned off between grinds, every time the wheel is started it needs dressing, as it may become eccentric on the hub. I was taught to start the machine and let it warm up while collecting the tools and work to start with. This next part is not the safest procedure but the most accurate. With the wheel running move the table to the extreme right to place the diamond on and secure, dress the wheel, and again move the table to the extreme right to remove the diamond. Move the wheel well up out of the way and clean the chuck. After wiping slide your hand over the magnetic chuck to ensure no grit or swarf remains. The wheel spins until the work is finished. The largest enemy of precision grinding is dirt in the wrong place, the second is heat, as metal moves as it warms or cools. Try it, you may like it!
I really don't see anything I would have done differently. Yes, checking the bottom would have been on the initial inspection, but the order of operations wouldn't have been any different (other than grinding the machine's mag chuck first, of course). Nice work, James.
If you are getting the results you wanted then you must be doing something right. Next step is start on the project to automate your grinder? Looking forward to that one 👍🏼
I have just had a look through all the comments so far. Nothing from Mr Renzetti, maybe he is still smarting from not getting on eBay first. This could make the BarZ bash a little exciting for you Mr Clough..... you might not be winning any competitions this year!! All this is way over my head, but great to watch. Thank you.
That Mitutoyo 2923S-10 dial test indicator is the most gorgeous thing I've ever seen and I have instant jealousy! Then I looked at the new price, $175. Well, not _that_ bad. Anyway, great video as always.
Congratulations James, that was pretty spectacular for a first go at trying to get that chuck to a much better tolerance than from the factory. I think anyone who has any experience with surface grinders would call that a win. And now you have a serviceable mag chuck for the sine plate system, ( after you've ground the sides square and all the other bits that is lol )
Sounds like you're the perfect candidate for my insanely good priced 8" x 24" permanent magnet chuck. No rust (really) and the price is even less than what you spent on the smaller one.
Begin by disassembling the chuck, followed by a thorough cleaning of each part. Proceed to individually grind the plates, ensuring they are aligned for contact and parallelism. Once reassembled, perform an additional grinding. This method addresses any geometric inaccuracies that may have arisen from incorrect assembly and avoids creating a chuck whose disassembly would disrupt its overall geometry.
I just watched a old video from Suburban Tool on a very similiar chuck. I also just finished rebuilding a 618 mag chuck, lterally just an hour ago. For once I beat you to a project.
One tip ill add is that when i was in the shop, we all used blue sharpies instead of a pencil for a flatness reference when grinding. the pencil is a little hard to see in camera, but i think the sharpie should pop for both us and you.
Nice, James. I'll admit that I was worried about flatness when you were hitting the chuck top pretty hard. But it worked, the proof is shown on the surface plate.
We had a guy at our shop that "cleaned up" the mag chuck every time he used the grinder. Didn't measure it, just ground it. Every. Single. Time. Shop manager wasn't pleased when I told him. But, hey, we got extra clearance under the wheel ...
I just purchased a compound magnetic sine plate on eBay. It is older and needs some help after it is repaired. I think that I will surface it in the mill first before putting in on the surface grinder. I am looking forward to see how it stacks up against the Suburban. Thanks for sharing.
not to be too nitpicky, but it looks like the mag on the machine had a little bit of a scallop/fish scale finish to it when you were done. there are two causes for this phenomenon: grinding wheel is slightly out of balance, or the arbor bearings have a bit too much slop. you can compensate some of the bearing slop with balancing the wheel better. and then dressing it. the machine i have has a built in wheel dresser which gives a really good finish on the wheel. if your machine can be retrofitted with one, it is an accessory that i highly recommend and would not want to do without on any surface grinder
As a person that loves to surface grind, I have found that using a piece of yellow legal paper under your part always works good for part removal from the chuck. For some reason yellow legal paper is very consistent at .008", or it used to be. But there will not be any scratches on the chuck when you're done.
Some nice work. I would have been tempted to remove that bottom plate and ensure it had uniform thickness, and possibly grind it by itself to ensure the chuck doesn't ring up with both top and bottom with matching slopes of a few tenths. However, that's the OCD kicking in. Do you forsee any issues with grinding the chuck while it's magnetized, but inspecting it while demagnetized?
James, I like your voice so much! Have you tried to narrate audio books? And thnk you so much for video quality. it's a pleasure to watch it on big screen
Don't try to recondition the Sine plate. It needs all parts ground individually using the pivot as a reference. You do not have the equipment to do that. Also if the pivot has any rust in it at all it will need to be rebored and pinned. Get a price for a factory recondition. Edit: BTW some mag chuck base plates have a VERY slight hollow in the center - allows the perimeter to sit dead flat.
One thing's for sure.......there ain't nothing like having a surface grinder even if it is well used and a manual model.......a shop without a surface grinder is a struggle place and I've worked a few of those in time gone by.
I'm glad somebody else has seen Hyperdrive. I tried commenting with some song lyrics, but apparently the humans and their culture will live to see another day.
Nice fix James! My suggestion would be to check your grinder accuracy from front to back. I think you will find the 50 millionth error resides there. Probably will just have to live with it or scrape the ways (Hmmm, another vid?)
You have to think in 3 dimensions. The chuck surface may be perfectly flat, but still coplanar to the ways which may contain the error. You could take a similar size piece of metal and grind it, then see if the error repeats. Then you will know it's the ways.@@Clough42
The error could be from going full wheel width on the grind. Small increments leaves a full size side of the wheel for longer when doing larger surfaces finish passes. Or so I was taught. Outside of training i have never used a surface grinder 😊
@@klausnielsen1537 I think either wheel wear or thermal expansion are at the root of the taper. Though let's keep perspective: 50 millionths is just fine for anything I will ever make. :)
We have stuff like that chuck at the shop I work at that is pretty well stuck in the 40s that I know has never been used and just from how this stuff was stored it's in similar to worse condition. I wouldn't be surprised if that chuck was new and was just in a shop like ours where nobody cared about it for the past 25 years.
Nice work. The finish “flatness” and “parallelism” is the final “judge” if you did a proper job.😎 My only suggestion is flip that dresser around. The diamond should be “facing” the wheel front not pointed “away”. Also, when dressing the wheel the diamond should be “past center” so that if the table is not locked and the diamond “grabs” it won’t explode the wheel, it will just throw it off. I always lock the table though when I’m dressing the wheel. Otherwise looks like you are doing fine work.😀
I don't think I've ever heard/seen that anywhere. Almost all directions I've been told and read for dressing the wheel say to have it pointed in the same direction as the rotation of the wheel, not against it.
OK, I'll be the odd man out. When I started (1970's), I ground chucks kinda like you showed here. One day, an old-timer that I learned to trust told me to grind my 6 x 18 so it looked like a wash board. So that required large steps and only conventional cuts - no climbing. My diamond was mounted in a rectangular block. At the end, you take that block on its broad side to each corner of the chuck, rotate it 30-45 degrees, and see if it sparks out. Repeat that in the center, front to back. I had to learn that how the chuck looks is nowhere near as important as the pieces you grind on that chuck. Heat is your enemy. Guys used to put Crisco over the entire surface, but I was the guy who introduced mist coolant. For the guys who insist on using the leading edge of the wheel, one could also use a 1-inch wide wheel instead of the 1/2-inch. Incidently, I used my same method on a war-era Thompson grinder with a 12 x 24 and could grind a die block that was maybe 10 x 14 dead flat. I think you did a great job for a newby!!
Some indicators are anti magnetic, and some aren’t. The better ones usually are and the rest? Well, take a guess. Suburban’s specs are a maximum error. Generally, my experience with a “new” tool from them is that the actual error is much less. This could have been new. It depends on storage. I’ve seen some new tooling that looked as though it had been used for years. But I’m skeptical. The surfaces that were rusty shouldn’t have been. The only thing I can think of as an excuse is the it was new, taken out of the box, cleaned off the protective oil and sat around for some time, maybe used once or twice.
I'm sure you have heard of this trick, but I will sandwich a piece of paper between something I grind when dealing with a mag chuck. Don't know if I am not supposed to do that but I haven't encountered any problems and the work lifts right off when the magnet is off.
Nice job, you should get many years of service out of it now. As for things getting rusty, I can literally sit and drink a cup of coffee and watch the rust form here in the Pacific North West in Winter when it's raining all the time. I literally have to leave a coating of oil on all my machined surfaces and tooling.
To start, I would have inked up the precision stone and printed the top and bottom of the chuck to see where the highs and lows were, then used the indicators. A good visual could help direct where to focus on.
I'm in the process of looking/buying a home in Eagle and you mentioned "No rust" which was a concern of mine as I have a full shop of wood tools. Very sweet words too. hear after living in places that even leaving a piece of paper towel for a day or two can sometimes leave slight rust staining on an untreated cast iron surface.. Being just an engineer (i.e.self taught in the shop) I always appreciate your semi-side tracked commentary re. Do/Don'ts, & Maybe's as they stir up valuable internal thought provoking/learning moments. re: "Should you use the Mahr indicator w/ or w/o the magnet engaged? I can think of so many arguments for both ways... Is there an absolute Yes or No answer?
To the best of my knowledge All Mahr indicators are non-magnet and are not influenced by normal magnetic field strength found in the average shop. I'm fairly certain that's not a guarantee for them however, and any medium Tesla strengths over .5 may have an effect since the gears are brass, the case and stem are stainless, and the springs are in tension rather than compression. MikeC
@CothranMike Thanks for the confirmation. From my limited machining background (but still wide breadth of engineering)I would assume the same as you stated, and I would assume the same for any "high" quality indicator. but who knows what type of tip (or even what kind of stainless) could be on some other imported pieces of equipment... it could be like wearing a watch into an MRI.
your variations are slight. but did you by chance make sure your entire (top and bottom) main mag chuck was true? saw you touch up the top surface. but the bottom of your new one bit you on its irregularities a bit.
Maybe it's just myself being a novice. But. If both sides are not flat. If you machine one side but the bottom is not flat, aren't you just making it worse? I would have thought you would need to use a level and some shims or something, to get you as close as possible. Am I wrong?
as you were grinding i noticed you made a pass and the shifted and then went back for another pass. basically you were clime milling on the way back. you should go back for the clean up cut before you make the next pass. and do i get a prize for being the 1000th like lol
Always a pleasure watching James' videos. Regarding the precision flat ground stones, kind of pricey for a hobbyist. Any reason not to use fine sandpaper with, say, a 1-2-3 block as an alternative?
Yes! They're a totally different thing. The precision ground stones have been made mostly flat so lots of surface area is in contact with the metal you run them over. They don't cut because you're not applying enough pressure to make them cut - sort of like how a bed of nails works. Only raised burrs/dings get cut by the stone because they concentrate the force or go between the grains of the stone and get cut. If you run sandpaper over your precision surfaces, it WILL basically sand it so at best it will be scratched. The budget option - and definitely not as good - is to take an old file and run it across a stone (preferably a decent diamond one but mainly it needs to be flat) and grind it until you put a flat on the top of each tooth. That way you have a flat surface that will run across the surface you're working on without causing damage but if anything sticks up, it'll get between the teeth and be sheared off.
To remove the chuck from the grinder does it help to put some compressed air on the corner where it touches the grinder chuck? maybe you can get some air underneath to pop it loose?
How many inches shorter is that chuck compared to when you bought it? 😁 I doubt the magnet in the chuck will affect the gauge much if at all, I expect the magnetic field will rapidly trail off as you move away from the surface because of the way the magnets are arranged inside. I think it's a Halbach array if I remember rightly. That said, it'll be a fun science experiment to get a Gauss meter and see what the magnetic field strength is like on the surface and an inch or so away with the magnet on and off 🧲
Magnetic chucks are nice basically. They direct magnetic flux trough tapered magnetically connective parts to smaller areas than the permanent has by separating areas with magnetically non conductive material. to either make circuit trough work piece or internaly trough chuck. High grip power is mostly because magnetic flux is denser in top of the chuck than it is on top of the magnet.
“Including you”, well,… I’m still using an angle grinder with flapdisk and my poor eyesight as measurement 😂😂😂 and guess what… still happy! You rock man!
How can the surface grinder give a flat surface, the gringing wheel doesn't become smaller with every mm of grinding?? I don't know anything about machining, this question is in my head the last 2 days!
@@Clough42 You may have been, it's just the fact that ebay sellers can't be trusted. I've been burned too many times on ebay. And then you can't even leave feedback because if you do they give you bad feedback in return even though you were the one getting ripped off. It's - Just Plane Silly - ....
I think one of the things that makes this youtube channel great is that you try not to tell people how to do things you don't know anything about. I say "try" cause you sometimes blead into it, but I appreciate the effort none-the-less.
35 years in moldmaking here. The only thing Suburban got right was their spinner. Never cared for their squaring blocks as they required frequent regrinding. Save up your dollars and look for Hermann Schmidt stuff.
I have been watching "upir" on RU-vid. He is doing interesting work with arduino pots and displays that you might find interesting for your applications where a full display may just not fit. I am looking to adapting his lighted pot to a guitar amp. Though I think it's beyond my skillset, I'll give it a go.
"Its not healthy going thru life counting millionths of an inch". It will consume you till there is nothing left to consume. Oh and what was the ambient temperature of the room when measuring?
Looking forward to seeing how you get everything square and parallel on that chuck. I wonder how the bottom got so far out. Maybe Don wasn't there that day. I expected you to bust out the electronic indicator for final inspection. Any reason you didn't?
As you step across the part for each pass, if you use a small stepover, only the edge of the wheel is doing any real work, and only it is losing any significant diameter. So while it may, after a while, not grind to the right depth, the piece of the wheel just inboard will still be the correct diameter, and will remove the bit the wheel edge didn't get. If you only step over in one direction, only one edge of the wheel will get the most wear. Eventually the wheel will be cone shaped from wear all the way across, but this usually happens long after you have completed work on a part. In any case, you grind in at least two passes: one or more roughing passes, and one or more finishing passes. You re-dress the wheel flat before you start the finishing passes.
The photo of the wheel has the model number written on it in sharpie. I do that because invariably the wheel adapter covers where it's printed on the blotter. :(
Well I would have thought: Outer surface of bolt- on base is crap. That means, the bolted on face is crap & likely the bottom of mag unit is crap too. Best option is to: Remove base and check / grind mag unit base. Then planar grind the bolt-on bit. Then bolt on the bottom bit & grind it. Then attack the upper (work surface) with the grindwheel. But during my deliberations, I wondered how many mills, shapers, surface grinders etc, do you know that have alluminium or lead or copper or mumetal or brass beds? I don't know any either. So: now my dylemma is enriched, I have to ask what sort of idiot designs & sells a MAGNETIC chuck / vice /base that bolts down onto a great big lump of Iron? Why not have a single actioned duplex magnetic system (dual surface / upper & lower) that releases from the workpiece & bed at the same time & visa-v magnetically grabs the machine & the work simultaniously? Less grief, less to warp, less cost and a gained z height.
Well best way to get as flat of a surface on a surface grinder that I know off is to have the part spinning well you grind it ( that way your only interdusing half if the grinders own axes flatness error over that distancecompared to the full error over the parts full size ) As we say in my country. The first pass is just a light pass to make sure that it doesn't just suddenlysay butthole on us
Just giving my personal opinion: I really prefer this type of machining content vs some of the 3D printer & electronics projects you've been doing lately.
Same. But I i don't think he's obligated to make every video for me. I'm free to skip the weeks that don't interest me. And I'm glad that content is out there if I ever become interested in the future.
