Using the Wrong Tool to Balance a Grinding Wheel
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- čas přidán 30. 06. 2024
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Today we're balancing a wheel for the surface grinder using an RC prop balancer. It's definitely the wrong tool for the job, but it might work anyway.
Tools used in this video:
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Bondhus Metric Hex Key Set (Amazon*): amzn.to/3eqZzwb
Bondhus SAE Hex Key Set (Amazon*): amzn.to/3h9bJLZ
HHIP 2-4-6 Blocks (pair) (Amazon*): amzn.to/2Wi03eM
Knipex Pliers Wrench 3-Piece Set (Amazon*): amzn.to/2ruzS8m
Noga MC1700 Mini-Cool Kit (Amazon*): amzn.to/2qgemiM
Raw Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 3.0 License
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00:00 Intro
00:50 Balancing hardware
04:38 Shopping for balancers
07:52 Prop balancer as a design pattern
12:10 Or maybe the prop balancer will work?
15:47 Test grind!
20:27 Inspecting the result
21:48 Wrap
I have hours of experience watching surface grinders on CZcams. Everything looks good to me!
Who said CZcams University isn't accredited?
In my case: days, so I have even more expertise, and I actually agree.
😀😁😂🤣😃😅😅
@@mpioman9885 CZcams UNI is way more accredited than the Universities that used to be great that now pump out activists rather than useful members of society with actual skills.
That’s funny
Your grind looks good to me.
Fish scaling or scalloping: Sloppy spindle bearings (doubtful, yours is new) Cold spindle, a cold spindle will usually have about .0001 radial play until it warms up. Balance combined with cold spindle is also common. (Who wants to wait around for 45 minutes to grind for 10 minutes?)
Stepover lines: Sharp leading edge of the wheel can create stepover marks, just touch the leading edge with a Norbide stick (after dressing) to make a slight radius, the leading edge of the wheel does the heavy lifting, the trailing edge does the fine finishing, grind either front>back or back>front, don't alternate.
Welcome to the rabbit hole.
agree 100%, make sure you take a well sighted in gun with you so you can get that dam rabbit if you ever find it;)
Thanks, Stan. I hadn't thought about warming the spindle. That's totally worth trying.
Assuming something is good because it's new, is pitfall I have to make a conscious effort to avoid. This goes doubly true for car parts. "It *_CAN'T_* be that sensor, I *_JUST_* replaced it." Uncannily often, it *_IS_* that sensor, off spec from the factory.
I know it's not a sensor in question and this isn't car, but I've found the concept applies universally.
@@charlesstaton8104 ugh. I hear you. Starters and alternators are the worst.
@@charlesstaton8104 This applies to so many things, in my industry $10,000-$20,000 power supplies have been bad right out of the box, $70,000 new out of the box radar simulators out of calibration, so cost and new don't guaranty accuracy or functionality.
The key to a good surface finish is to, before starting starting up the surface grinder, lean down and whisper "you can do it, buddy". The difference is like night and day.
Just remember not to do it AFTER you have started it up.
Or just tell it if it doesn't perform, you will ship it to ElectroBoom or AvE for a live post-mortem.
Peter again if you want better finish try on the spark out passes lightly run a 1200 die makers stone across the wheel face.
It's more in how you hold your tongue after you whisper.
To inspect your true surface finish, take your precision ground stones and run them over your ground work. This will expose balance issues, wheel hop, step-over and any heat you may have put it the part from grinding. Use this to perfect your skills. You’ll be surprised at how much this will show you
The rolling type balancers shouldn't be underestimated. A good one with hardened steel rods is *very* sensitive. They are also very easy to make. It would take air or magnetic bearings and large wheels to be more sensitive. You prove they are accurate by flipping them around, just like calibrating a precision spirit or electronic level.
Grinding wheels are funny things. Eccentricity makes them imbalanced. Balancing and dressing can throw them a little bit out of balance again, and they will dress a bit eccentrically again! It may take 2-3 sessions of balancing and dressing to get them close to perfect.
Never use aluminum on any balancing device, it dents microscopically from weight.
I agree with you and a balancer using even drill rod like the one I made seems to work very well. Getting the balancer level is of course very important so I use a precision machinist level. I am quite pleased with the results I get with my Harbor Freight grinder I bought more than 10 years ago. I can grind test blocks in 5 places on the chuck to within a tenth. This is more than good enough for a HSM.
I actually ordered a couple of HSS drill blanks to use as rails, and the ones I received were awful. The grind on them is so bad you can file your fingernails with them. Guess I need to throw a couple into my next McMaster order.
@@Clough42 Yikes, that must have been disappointing! In a pinch, I guess you could sand them longitudinally, which should make a smooth rolling surface even if it appears a little rough. I hope McMaster's blanks have a better finish!
I saw a great tactic for balancing wheels. You use an accelerometer and a tachometer and connect the two to an oscilloscope. This way you can see the phase difference between the vibration and place you put the reflector
Accelerometer and Scope... That is right is James' wheelhouse.... I smell a follow up video....
Was this on "The Gadgets Playlist" channel? He's done a number of videos on building balancers - pretty sure before he retired he used to do balancing professionally
@@gorak9000 don't remember unfortunately
"Real" aircraft propellers have relatively inexpensive setups to do this.
@@UncleKennysPlaceAviation and "relatively inexpensive "😊
1. Anderson balancer is the ONLY way to go to get a good balance. (The one shown in your video for $1925.00). I looked for 4 months & found a used one for $250.00 & it's perfect. They are available. Even the guys @ Anderson told me not to change the wheels: each wheel has a precision bearing & is balanced @ the factory. Wheels for my balancer, (which will hold a wheel up to 22" in diameter & 10 inches wide), sell for over $200 each. Spin a wheel with your finger @ it will spin for about 2 1/2 minutes. 2. Make your own test shaft--I did. Between centers & taper of 1/4 inch to every inch of width. Simple to set up & turn.
3. Wheel goes on test shaft & tap shaft on solid surface to seat. Test your shaft with machinist blue to check contact. It will stay easily if the shaft is correct. 4. Every time you mount your wheel in machine, true it. Diamond tip should be about 3/4 inch behind center to make it be about 15* angle of contact. Too close to center will wear the tip off of the diamond. 5. Your finish grind shows signs of hopping. Look @ the reflection & you can see it. Slow your pass, decrease step over until wheel grinds very smoothly. Watch for loading.
6. My finish pass with an 8 inch Radiac ceramic wheel, 36 grit, on 55 Rockwell steel is .000025 inch to .000050 depth @ .005 inch step over & it produces a mirror finish that you can shave with. Try it & see. I can't even get that good a finish with my 150 grit diamond wheel, no matter what I do. 7. Check out Steve Barton @ Solid Rock Machine Shop on CZcams. He's the best I've found. Works within 50 millionths of an inch & his products are unsurpassed in quality & accuracy. Sorry this was so long....
Steve Summers put up a video several years ago about using the DuBro balancer for grinder wheels in the shop. He says it works great. I got one for my balancing needs and agree with Steve. Just handle it carefully and be gentle. It should last indefinitely in the home shop.
Ha! I didn't know that.
Well done for remembering who it was.
@@tonyray91 it wouldn't be hard if like me you are an avid follower of Steve's channel. I visited his shop last year when on a trip to the states from England. A really nice bloke and very humble.
@@samrodian919 Yes, I know he has to follow the interst but a bit of a return to machining would be welcome.
I'm also new to surface grinding and learning every day. One thing I did learn was, after you balance a wheel, then dress it. If you put it back on the balancer, it show out of balance. So, I've had the best luck and the best finish, if I balance, then dress, then balance again, then dress again. It's a little longer process, but way better results.
It's the same logic when balancing tires. Mount them on the machine, balance them then loosen the tightening mechanism then move the wheel/tire 15 deg or more then re-balance it. You may or may not see any changes but it's worth the extra 60 seconds. Probably 20 minutes on the grinder.
Honestly, I never balance my wheels. I give em' a ring test, throw them on the arbor and just dress it true. Never had an issue...
I think you may have a few things that are contributing to the surface finish that you are getting. I have been in the trade for 30+ years now and a couple of things..
First the type of coolant is very important, we always used grinding coolant as apposed to milling coolant. My experience has shown that if you are using a milling type of oil, the wheels would tend to clog , and this led to poor finish and even burning of the part.
This leads me to the second point.
You really need to use enough coolant to really keep everything really cool and theotetically you should not see any sparks, especially on light cuts. Also bear in mind that the coolant is also there to clear the wheel in operation.
The other thing that I have experienced is that some of the modern import grinders don't seem to be as rigid as the old school (Cincinnati for example) machines and I found that I just couldn't get the same quality finish unfortunately.
Hope this helps for what its worth.
Adding to this statement "You really need to use enough coolant to really keep everything really cool and theotetically you should not see any sparks, especially on light cuts. Also bear in mind that the coolant is also there to clear the wheel in operation"
The coolant we used in my parents shop for the cylindrical and surface grinders was the same overall coolant from Rocol, Just at a radically lower concentration - recommending 20 to 1 for cutting and 60-80 to 1 for grinding
One part that needs to be considered is that mist coolant may cause more problems than flood coolant - Just like a whetstone, The wheel will be absorbant and swell until it is saturated - with mist I doubt you will reach that point and will be loosing some accuracy: but we are talking a few tenths of a thou here
i dug an old TOS tool grinder off a pallet, cleaned the dust off it, set it up, ground a few chunks of carbide for a job.
boss whinged and whined that i "wasnt a machinist, it wasnt economical".
i got the effin job done. along with several others...
he sold it. $500. glad i pinched the magnetic chuck.
same job(s) comes up.
cant do...
"why not?"
sold my grinder, you wanker. (ad verbatim)
"it wasnt worth the time..."
so youre telling me its more "economical" to now send the carbide away to get ground the same way i did? FFS...
never got them jobs again. lost a big contract for FAE... those forestry mower things.
i left. paid a visit one time. oh my... a new surface grinder hiding in the corner... not even a shadow against that TOS. chinese rubbish.
can you tell it still hurts me?
I feel the pain!
That's exactly what my professor told me, start the machine let the coolant fill the grinding wheel fully. He always told us to be keen on not seeing sparks. He did have a similar idea on the oil, he was also very keen on the mixture to avoid inverted emulsion.
@@paradiselost9946 good call leaving the wanker! Even though you used the dollar sign, you sound to me like you're a Brit, (like me) working in the states or Canada maybe?
I still have my Dubro balancer from my RC flying days over two decades ago. I'm always finding new uses for it and it always continues to impress me.
Finally, a long awaited episode that delivered pure entertainment. I look forward to the next release! Looked like a nice grind to me but I'm not a grinding expert.
I might be being too particular. That happened that one other time. :)
@@Clough42 YOU!? No way! 😂
Started this video and you spoke of making a balancer for the arbor. I stopped the video to find a link to the one I have used for many years. Came back and continued your video. :) you brought forward the very same one I've used forever with my R/C planes. You got this, those things will last forever. Like all precision machines even the smallest need care.
Good job, appreciate the video and the time you put into it so we can enjoy it.
If you want a balancer with 2 horizontal rails, you might get some inspiration from "Adam the machinist". He makes high precision jigs with....3D printed plastic and carbide rods. He shows that plastic differential adjustments are surprisingly effective.
As a matter of fact, I have already 3d-printed something like what you describe. :)
I’m glad to see other fans of Adam. His channel is under appreciated for the quality of his work.
Adams channel is amazing
Love Adam's work. Up the Robin and Stefan
My first thought for this went to graphite air bearings, which are surprisingly easy to make. Virtually no friction, and by carving the channels after assembly you can get rid of almost all misalignment. You could also add a feature to the part of the arbor that goes in the bearings, such as a flange, and a corresponding feature in the bearings, you could "key" the arbor axially, while still allowing free rotation.
I have that same balancer and was going to try the same thing. Glad to see that it worked.
I was looking at the same cheap propeller balancer for my small surface grinder. Thank you for trying it out!!!
nice job James very clean very clean work thanks for sharing the time with us
Funny, I literally just 5 minutes ago minute threw that same balancer in a box of rc stuff to sell. Now thinking I should keep it for this purpose 😊😊
Good work James, I found this interesting even though I can’t use the knowledge, yet.
For friction free bearings the first thing that came to mind was some kind of air bearing. Maybe others who have used such things can chime in.
I was watching you balance that prop. My dad the aerospace engineer just taught us to sand a little off the end of the heavy blade, no sense of using tape or that blob of glue. That Du Bro prop balancer works great on small stuff way past 20,000 rpm. Great Video!!
Another great video James. If it works or works well enough for your use it is an excellent use of existing tools to meet a purpose as opposed to purchasing an expensive tool that would have limited use.
I don't claim to be an expert at surface grinding. I've been using a similar Radiac wheel on my grinder for several years now. I don't use it that often. Started out with a 8" OD wheel now around 7"- 7-1/4 OD. Have never used a balancer to balance the wheel. Does leave a nice finish most of the time. I noticed the last time I used it, it started to leave a ripple like you had shown before balancing the wheel. Time to try your balancer and see if it makes a improvement in the quality of the finish.
Your grind sample looks very nice! Thanks for the video, Ken
Great video, I think the simple little prop balancer worked fine. It worked to do the job and I think you can build one that will work for heavier and/or larger wheels. The finish appeared very good. I think it worked great.
Thanks for sharing.
I had the really simple prop balancer that just held the shaft between magnets. Excellent idea!
Thanks I've needed to build one of these for a while.
While I was in the Navy, we used accelerameters to balance the rotors of the generators.
I guess using it is easier than spelling it. 😉
@@interstellarsurfer While EM doesn't mean 'english major'.
@@matthewmiller6979 Well said - spelling nazis are the bane of the fart (sorry fat) finger typist.
James, reading the comments .. you’ve got to try the accelerometer method. It would be so you (and, to be honest, me). I’m waiting …
@@zorbakaput8537 I love it. 😆
I have a couple prop balancers. I actually grabbed one identical to yours that was behind me while watching the video. Great idea.
One of my uncles worked for Liford grinding X-ray photo plates, they used two devices for balancing the wheels, the first one for initial balance had two parallel knife edges as sharp as razor blades, the second used air bearings on the shaft and flashed a dot of light to show were to add weight or remove it. My Uncle said the balancer machine cost as much as a grinder and him and another guy were the only two in the shop certified to use it. the machine reminded my of a tire balancer refunded and shrunk.
I've designed infant pendulum swings for 15 years that rocked infants to sleep. We paid a lot of attention to bearing decay, as the lower the friction, the better they would work. One year instead of a hanging pendulum style seat, we made a curved track and wheel system for the child's seat to "rock" on. I was in charge of the drive and track system. I prototyped many different track, wheel, wheel cross section, ball bearings, plain bearings, etc. And counted the system decay on each one. What that meant was putting a 20lbs weight in the seat, pulling the seat to the hard stop of the track, and counting how many cycles it went until it stopped. It ranged from about 8 cycles to 70 cycles, with all the different combinations. This is all very relevant to the balancer you showed. What I found was the following: The smaller the ID of the wheel, the better. So if a plain bearing, a shaft diameter of 1mm worked better than a shaft dia of 4mm. If a ball bearing, a shaft dia of 4mm worked better than a shaft dia of 8mm (608 skateboard bearing). In all cases, a ball bearing worked better than a plain bearing, even a small plain bearing compared to a larger ball bearing. Next was the wheel diameter that the bearing was mounted inside. The larger the diameter, the better it worked. A 2" wheel was much better that a 1" wheel, etc. Last was the cross section of the wheel and how it contacted the track. In general, the smaller the contact area, the better it worked. I had about 100 data points on all the variables, and plotted them all out, and that led to the mass-produced product that we sold tens of thousands of. So in my experience, if I was to make a wheel type balancer, I'd use a much smaller bearing than a 608. Something with maybe a 4mm ID from McMaster. Get the FAG brand that's what they sell if you get their Japanese bearings, and they are very high quality. (sorry, this was 10 years ago, I forgot the bearing trade numbers now). Then use a large diameter wheel. Maybe 2-3" in diameter. Turn the wheel on the lathe and bevel its edge to maybe a flat about .050" wide. Smaller would be even better, but I think the risk of it getting dinged will override the decay advantage. IMO:)
Hello….I not only use the same Dubro balancer for my RC props, but also for my lawn mower blades. So far it works great!
I have one too, works great.
A very useful review of the balancing stands. Thank you. Was good to see the range of prices. I have one which looks like the $629 stand, which I bought for about $20 at a flea market. Cheers
I had made the exact same style of balancer for my grinder, I used small bearings but their was too much friction, then I tried larger bearings which helped but still not satisfied. I was considering using the round stock or putting a inverted Vee on the top of the side pieces and getting rid of the bearings all together.
I had operated a Berco crank grinder and a large surface grinder and both used the large wheels for balancing. I deduced that you need the fulcrum effect that the wheels provide with the low friction of small bearings. Now you have given me another consideration. Machining the tapered disc's and keeping it all concentric was a concern.
Another nice video. Always well presented.
Thanks for the video! It would be nice to hear your thoughts on dynamic balancing too (not just for wheel; but in general)
Years ago I used the Du-bro type balancers for model prop balancing but then switched to a magnetic balancer, it was much more sensitive and settled quicker. Absolutely no friction or rolling resistance. When I got into larger models I made a bigger version. The only critical dimension is the concentricity of the shaft and mounting cones. With the rare earth magnets available today it should be easy to make one large enough to carry a grinding wheel.
I have never seen a magnetic balancer for grinding wheels. I agree it would be ideal, but that's a lot of weight to support, and very expensive it it slips out.
I have a balance wheel setup similar to what you have. Wheels are about 150mm tapered to a near sharp edge using ball bearings with the seals removed. I use WD 40 to clean foreign material out of the bearings before each use. Very accurate. My wheels are 10" and 12" diameter. George from Indiana
Have you thought of the magnetic style bouncers. I use them for rc props and they seem to be far more sensitive. They also will never wear out. You would obviously have to build a bigger one to hold the weight.
I had a conversation with someone about those this week. I suspect it would work great, but would also require very powerful magnets.
They also sag so the wheel spindle may not be horizontal. Does this matter? I don't know.
@@Clough42 i figured it would need large magnets. I am curious of how well-balanced you can get a wheel and doesn't make a massive difference. if the regular rolling style balancers are good enough then i would think what is ever. Cheaper is best
I painfully went down this same rabbit hole a few months ago. Static balancing is good, but the king of balancing is dynamic balancing. You identified the core problem, overcoming static friction. If the magnitude of imbalance is below the amount of leverage needed to overcome the friction, it doesn't move. Or it settles into a position that is not truly indicative of the imbalance. Dynamic balancing can reveal greater detail, below what is needed to overcome the static friction. All one needs to do it install a reflective sensor on the mounting wheel for phase, as well as a *very* cheap accelerometer, and then run those two signals into a pocket oscilloscope and you can balance in place on the machine. :D
I made a motorcycle wheel balancer with skate bearings, and I pulled the seals out, washed the grease out, and lubed with kerosene. I can detect less than a gram out on a 5kg wheel!
This is the path I'm on. :)
The finish are getting could be due to the hardness of the block. I have always notice a difference in surface finish from soft and hard. Most surface grinding is done after a piece has been heat treated. Also I can’t remember if you did but ALWAYS grind the magnet after mounting it on the grinder. If you are new to surface grinding that will be a learning experience in itself, tip plenty of coolant while grinding the magnet and make sure the magnet is turned on.
Several years ago I worked with a precision machine shop who made aerospace parts, specifically large optical mirrors at the time.
I noticed they put a lot of effort in iterating between redressing the grinding wheels and rebalancing them. They mentioned their static balancer was designed and built in house and used magnetic bearings (and worked better than a dynamic balancer they had purchased).
I haven't been following your video series, but if you really want to balance your grinding wheels as best as possible, you could probably come up with a relatively simple magnetic bearing setup yourself.
How about air bearings? That'd be an interesting project.
Thanks for the video. I love seeing tools re-purposed for things they never were intended for, but balancing is balancing.
I recently used a record stylus scale to compare the weight of some some coins. Worked like a charm!
My experience of the Du-Bro balancer is that it is very, very good for balancing lighter stuff like propellers for model air planes, which is its purpose.
It is also suitable for balancing heavier stuff like grinding wheels, but it seems like the friction in the bearings somehow increases with the heavier load. The bearings might not be premium class, but who could ask for that when the complete balancer cost less than just one premium class bearing?
But still, the Du-Bro balancer is extremely good for its price and it is good enough for most of us.
But I would recommend removing the grinding wheel from the balancer when moving the weights, simply because the balancer isn´t meant to be used with the weight of a grinding wheel. Add to that the forces that you inadvertently add to the balancer when working with the grinding wheel and you might stress those tiny bearings even more.
Anyway, good video, thumbs up!
Cheers from Sweden.
It's incredible how much money you can save by clever application of cross-industry parts/tools; economies of scale can sometimes put things way out of whack and result in getting a lot of bang for your buck if you're smart about playing to the strengths of whatever part or tool you're co-opting.
I've got a couple tips for you.
1. Use the appropriate wheel hardness for the material hardness. Softer part = harder wheel. Harder part = softer wheel.
2. Rough on one side and finish with the other. It takes more time since you'll be traversing back mid air but the last thing you want to be doing when chasing a critical size is having both edges of the wheel worn out/glazed.
3. I suspect your balancer is too light and deflecting under the load. I use an Anderson 40 balance stand and never gotten a lucky balance.
4. Here's how I balance the wheel:
4a. Unload all weights and true up the wheel (dress enough off the wheel so it is round, I've taken up to .020" off)
You can dab a bit of crayon to the wheel to make sure it all clears up.
4b. Place onto balancing stand and locate the heaviest spot. Put one weight directly across the heavy point.
Check that the heavy spot moved. If it didn't, you could use two but you should begin suspecting something.
4c. Place the two other weights equidistant around the pocket.
Fiddle with these two weights only.
Check out Cutting Tool Engineering's youtube channel (@CTEplus) for more Science behind grinding.
That wheel is actually one that I use at work with flood coolant. You can have the spray going onto the part/table, but getting the spray into the pores of the wheel to keep the swarf out of it will definitely help more, in my opinion. Your feed looked a little fast, maybe half or three-quarters of what you were going may improve the surface finish as well. Also, balancing isn't super critical if your tolerances are around +/- .001 as it can easily hold that with just a dressing of the wheel. When you get into a tolerance of +/- .0005, then you want a good balance on it.
I don't know if anyone else has said this -- You can find "LEVEL" by taking a standard bar level and placing it upon your stone flat surface plate. then rotate the level up to 360 degrees in the horizontal plane until it shows "LEVEL" in the spirit bubble. Then rotate the level 180 degrees to verify the spirit bubble bar level is actually accurate, thereby indicating the "LINE" on which your surface plate is level on. Place your balancer on this line and it will be level to the accuracy of your spirit bubble... A better spirit bubble level will deliver better results.
Hi. We have couple of these type machines. Each wheel that is delivered is checked in weird way by operator. He taps wheel with small hammer and sound has to be even all round wheel. If not he states wheel needs drying, it efects the balance. Also homemade unit for balance using tile cutter replacement wheels, same design as prop unit. The bed gets a very small grind after wheel has been done with diamond tip. Hope this helps🤷♂️
Very interesting video. Thanks for the video keep on keeping on.
Great content! Keep'em coming
I made my own arrow shaft spinner by hacking up the casings of old magnetic disc hard drives (exposing the discs) and fixing the remainders in pairs, much like the wheels of the prop balancer. Big discs; delicate bearings; discs precisely sized and balanced and mounted on those bearings. Wasn't pretty but it worked.
I've learned so much from RC aircraft, I've balanced many things on the same dubro balancer , shafts , motor armatures, all nothing to do with the hobby. If it gets the job done no harm
I'm no expert but got about 15 years as a tool and die maker at a bearing manufacturer, got a few things that will help you.. that coolant isn't going to work. It's not directly in the cut, you need to flood that right in between the wheel and the job.
Don't get truing the wheel confused, when you mount the wheel you true it first to balance. Dressing exposes new grain structure to allow the wheel to cut. Now I always worked on Jones and Shipman surface grinders which don't have an Arbor just like yours and we always mounted then trued up the wheel to balance and was always good, I know wheels are never consistent but it worked fine and what I was taught to do as an apprentice.
Not sure on the colour coded you have in the US but that wheel would be softer here. I would probably grab an aluminium oxide wheel. To grind mild steel. As they are generally harder acting.
Best truck to check for true to is to grab a wooden brush handle and just touch it against the surface of the wheel, you will feel any vibration through that and it won't bounce like steel.
A wheel never cuts at its best straight after a dress, generally it's just to Sharpe and you need to grind a couple of parts... That's more of a general rule..
The last thing and probably the most important. When you mount a wheel and start the spindle you dress it and then don't stop the spindle. You leave it run, spindles could be on for days...
Oh and don't forget to ring test a new wheel and let them dry for 10 mins if using alot of coolant. 👍
When I balance a wheel, I start without any balance waits. Find the heavy spot, then place two waits 90 degrees from that spot. Now more each wait toward the heavy spot. Retest, and adjust until you achieve balance. I have never understood how you can use three waits to achieve balance. You just keep chasing the balance until you finally luck into it. The two wait method always works with a minimum of fuss.
That is also my way to do it, this is the fastest and most correct way to balance a wheel. The most important is to place the first waits very precise.
The Dubro balancer I own has been used for anything from hollow 20" Carbon blades weighing under 7g to spin at 1200RPM to 4" Pylon racing props doing 30+k RPM and 1/4 scale wheels and pulleys and ..... Great bit of kit for the $
Great video! And awesome tip I’ll probably be buying one of those balancers to experiment with!
PS. I hate to be the guy but I cut about 3/8” of pointer finger off cleaning my grinder with a rag like that while the spindle was turning. Do what you’d like with that info lol.
Keep up the quality videos and keep your digits!
by counting the oscillations and measuring amplitude, you cam estimate the friction to a high degree and hence the accuracy. Also by taking the center of final postion from both ways, im pretty sure you can get within a degree from what I see. Also using a pin drill with a bit of fine cerium to polish in the pins, clean and lubricate with a drop of isopropyl, That prop balancer will probably match the performance of a set of ground rails.
First one of your videos I've seen. >SUBSCRIBED< great little demo, really like the tone of the video! looking forward to seeing more.
You can overcome bearing static friction by wiggling it rotationally. I balance motorcycle wheels an an arbor and two bearings sitting on sawhorses. Just bumping one bearing slightly makes them turn relative to the wheel/arbor inertia, breaking the friction. As long as you keep it moving, it's extremely sensitive. 8 used this technique to balance a large fan in the motor shaft by rocking the fan housing slightly until the heavy point settles.
If I wanted to make a balancer for myself I would look into the engineering and technology of automotive wheel balancers for inspiration .. I mean if youre going to go through the trouble, might as well go big
Another useful and informative video James...Thanks. Now I gotta go root through my old RC stuff in storage to find my DuBro balancer. I have a stalled attempt at fabricating my own flanges but might find it easier to source the ones you used in this vid. Can you share the link to where you purchased them? Looking forward to more surface grinder content...Thanks
you just need to find the right stone and keep on using your balancing jig and you'll be fine. awesome vid 👍
Not an expert or even proficient on a surface grinder by any means but the surface finish looks great to me James! 👍👍
Would love to see a shop made balancer as well as seeing you CNC the grinder in the future.
Looking good James. I recently built a bearing/roller style balance for my grinding wheels as well, and quite happy with it. I used Boca Bearing MR-6300C bearings. They are steel race/ceramic ball, with the dust seals and grease removed. I'd pass on a photo, but not sure how to go about doing that here?
There's an interesting tradeoff between deflection and mechanical advantage with that balancing shaft.
Plus, you have to assume that the shaft itself is perfectly balanced...
I made one using hard drive platters on 4 dry ceramic bearings. Riding a simple frame I welded up using a chunk of 5in x 2 steel C-Chanel with shoulder bolts used by stamping dies to hold the bearings..
Any wheel you use needs to be balanced and harded to nearly the same as the shaft the will be used
How fortuitous. I need to balance a cheap CBN cup wheel for my drill grinder. I don't really need another project so I'll see if i can get a Dubro prop balancer. Thanks.
Hi James.
I'm wondering about re-dressing the newly balanced wheel. Wouldn't dressing introduce new unbalance? It feels to me like one of that multi-iterative processes that influence each other.
In the same way that bumping in square stock on the lathe chuck concentric *and* perpendicular influence each other and have to be done multiple times in a row.
I wondered if you’d posted. And here it was. Excellent content as ever. Maglev is clearly the proper solution here. Break out the liquid nitrogen
Ha haha! "Some aluminium that came out of the scrap bin". I wish I had a scrap bin like that.
Your balance looks good, the chattery finish is a sign of a dull diamond or too slow a dress. Softer material=harder wheel, softer also likes a more open grit structure.If the wheel is "bouncing", its to hard, out of balance or needs more dressing. Coolant(especially oil based) needs to be mixed lean, think 5%, I have found synthetic best for grinding. Consider putting your part at 45 deg on the chuck to limit heat build up. .001 is an ok ruff cut, on soft ,a big cut loads the wheel, on hard material, it wears it. Ruff , redress, then .0005 and sucessive .0002 finish cuts and spark out passes. On CRS, Id use a J or K wheel, a porus wheel would be best. Also, tighten the nut on the wheel adapter as tight as you can, loose wheels slip and will be out of balance again in addition to being out of round. I mount, dress, balance and dress again. Some grinders are more fussy about balance then others.
Thanks for the tips. This is an open structure wheel, but it's a G. I have a K, but was getting similar results. The soluble oil coolant is mixed at 20:1, which is the 5% you recommend. I've done more balancing work since and have some better results. Video coming soon.
For something as heavy as a grinder id recommend the method matthias wandel used for his planer blade. Idk if that comes precise enough but its certainly a good method for a rough balance
Place a small clear plastic cup of water on top of the grinder cover and look at the ripples to check for vibration.
In my former Die Shop we never balanced the wheels. We did dress new wheels as soon as they were installed.
Think about it as you dress the wheelthe balance changes.
We would also flood with Fuchs coolant.
We ran a 60+year old Thompson and 30 year old Chaviler grinders.
When balancing a Grinding wheel, Start off with all the balance weights removed, so you can find the "Heavy point of the wheel".. then Mark and mount the first weight directly opposite of the heavy point, that way, the center of mass is on the line between the heavy point and the first weight.
Keep that first weight where it is.. and place the other 2 weights symmetrically, you then have to move the both of them up or down to properly balance the wheel.. with some experience it can be done in 5 minutes..
i Used this method for years, and colleagues always turned to me to balance the grinding wheels..because it would take me 5 minutes..
With any roller bearing system, the technique of "position, release, observe" can only get you so close to a true balanced state. One needs to initiate rotational force sufficient to obtain one or two full turns of the wheel before observing where it comes to rest. What's more is that you need to repeat this multiple times to ascertain that it comes to rest in the same (or very near the same) location repeatedly.
THIS is the difference between balancing on rollers and balancing on zero friction hardened rails.
We do this in watch repair to balance the balance wheel (except the rails are knife edge ruby rails).
Thanks for the great video! I’m exploring different options on balancing slot car motor amateurs and wheels. Looks like what you did should work great for grinding wheels. Wanted to offer my opinion about your surface finish. First let me say that getting a good ground finish on mild steel is tricky and yours looks acceptable. If you wanted to improve it, I would try switching to a non porous Norton 60 grit wheel or equivalent.
The Radiac wheel you're using is a porous 46 grit wheel. Porous wheels grind a little cooler than non porous wheels and can be used without coolant in some cases. Since you have a coolant setup, I’d try a non porous 60 grit wheel, balanced with your method, and it should improve your finish.
Hey you know what'd be sweet, a wheel balancer using porous carbon air bearings. They're not so expensive and i've even seen hobbyists like AppliedScience make them on youtube very easily, and then demonstrate theri sensitivity!
I use iso-molded graphite for nozzles in high-power rockets. I tried to test a nozzle o-ring seal by plugging the nozzle, immersing, it in water and pressurizing the casing. I was shocked to see the tornado of air leaking though the graphite. I couldn't get it to 50 psi through my compressor regulator and the motor lpruns at 1000 psi!
Sidenote- there is a static balance and a dynamic balance. Dynamic balancing is the one to go, especially on higher rpm it becomes more Important 🙂
since you statically balance each wheel independently, this is the same as dynamic balancing. no difference
I have seen self balancing wheels where the mounting flanges are split with a circular groove between them and a good number of ball bearings inserted. any vibration causes the balls to move - eventually when the vibration stops the wheel is in balance.
That's slick. Do you have to start it and stop it multiple times to get the balls to settle down?
@@meocats it would rebalance every time you start it
Looked like that worked perfectly. Don't fix what aint broke.
As soon as I saw the Bearings model, and he says it did not work because of Friction. Immediately I thought of CERAMIC.. We use them in Fishing Reels, and they are very very fast , and extremely low Friction. Any Oil in a Bearing will slow it down somewhat .
There are two type of unbalancing. This is a static balancer and for this thin shape maybe enough. But dinamically unbalanced pieces can cause of vibration even they indicaing statically balanced perfectly. Tyre shops use dynamic balancers. Those are much hard to build but i'm sure you could do it if you interested.
Can you lightly dress the sides of the wheel to reduce dynamic imbalance?
@@Bob_Adkins Unfortunately i'm not an expert of this, it depends on how the mask divided on the wheel causing unbalance. Briefly, dinamc unbalance is when the axle of mass is not the same like geometrical axle. See wikipedia, it is much clearer than my explanation
*mass
Regarding wheel choice on the advice of the guys on the Practical Machinist Abrasive Finishing forum 46:grit J or K is my go to wheel, I get good results on tool steel, mild cast iron. You are using Radiac - which I could get them in the UK. Steve at Solid Rock highly recommends them. In time you will probably improve your finish but the difference will be small, I’d be happy with what you are getting now.
Hi. Great video. Do you have any links or information to the supplier of the the balance arbor? I can’t seem to find them for typical US style taper spindles. Thanks!!
Balancing and dressing are all important. Try setting the work piece at a 30 degree angle to the fence. Then down feed about .0005" per pass and reciprocate the table very fast. On the final pass, no down feed, but use a fast reciprocating motion. Of course harden steel and chromium steels will result in a better finish. Wheel selection: now that's a whole new video!
I hope you don't mind, but I have a few tips for you. First of all, always remove the weights before balancing. The first step is to look for the heaviest spot on the wheel. When you get that, the heavy side will point down, so put the first weight on top. It's very important that you can't move this weight further on. The second step is to determine whether the stone or the weighted side is the heavier one. For that, you have to rotate the wheel 90°. It will roll again, so when you have the heaviest spot, put the 2nd and 3rd weights in a symmetrical position to the light side (e.g., +30 and -30). Rotate it 90° and see which side it is rolling to. Now, you only need to open or close the angle between the 2nd and 3rd weights to balance the wheel. It's important to do it in pairs and symmetrically.
The second tip is that after balancing, do a proper dressing. Mark the wheel's circumference with a marker and dress it until the paint is gone. After that, check the balancing again and correct if necessary! Trust me, your spindle bearings will thank you for that! This way, you eliminate chatter (parallel lines on the surface) and vibration.
And finally, check the balancing once in a while. With wheel wear, you will get a completely new weight distribution. For example, you might dress away the "heavy spot" quickly, so you are "unbalanced" again.
This is how a Japanese engineer taught me how to do it. He is a service engineer for an almost 100-year-old Japanese brand.
Balancing is very important to keep the bearings' condition, and on a precision grinder, it's all about that. I know some of those balancers seem to be very expensive. But if you take care of that, it will last forever, and definetly look after your machine's condition. I hope everything was understandable; please forgive me if not. I'm not a native speaker, obviously.
I always perform balancing and trueing in a regressive manner, balance then dress repeat at least once. If you balance then dress you removed material that may affect the balance etc. I always do this on a fresh-mounted wheel.
Check the design of a Jones and Shipman wheel balancing unit. Instead of ground rods as rails they use knife edges these are brought into contact with the arbor by means of a cam. They have 3 feet on the base 1 fixed and 2 adjustable so that you can center the bullseye level.
I believe that a clever guy like you could make a wheel balancer with a couple of drill blanks and a few leftover scraps of steel, or aluminum.
Nice with the prop balancer. I have an Anderson, one of those 1900$ type. Works great even on grinding wheels, but I have also done some large items. nice grind, oh listen to Stan.
try bluing that arbor to find what the fitment problem is , small burr or wrong angle taper
I built an air bearing balancer out of junk inside a couple of hours. Works absolutely perfect. 🎉
I would love to learn
how to make simple air bearings such as you mentioned. Are there any CZcams videos showing how?
@@ellieprice363 I’ve not been posting but I’ll try find time to post a short one. I’ll name it, “simple air bearings for wheel balancing”.
spring pass without coolant.
only go one direction from in>>out or out>>in going both is out when taking a few tho but not if taking less then a tho
also might want to pull and clean the rails the table glides on grit in the bearings or bad rack mesh can make this happen as well
That looks like an archery arrow spinner!! It typically comes with wobbly frame that goes in between the end bits. About $40 CAD where I am at.
It's probably worth a laugh at this point, but I modified a du-bro to balance my first 254mm compressor section for an axial jet engine built from a cornucopia of other jet engine parts. Did the job, but I started banking out for professional laser balancing when going larger than that. Peace of mind at 85K rpm is certainly worth something.
I think the wheel/material combo you're using is the main hindrance to finer surface finish. When grinding vanilla 1018 CRS and I want "wringable" surface I usually use a 32a120-kvbe with a closed dress for my finish passes. I've also had a great time with straight AlOx wheels (pure white in color). I think a longer warm up will help too. These tips worked on a full wet grinder instead of mist cooled, so you might encounter burning with a wheel that hard? Hard to say.
I should clarify, by "wringable" I mean I could wring them to a clean granite surface plate, but If I had 2 workpieces treated in the same method they wouldn't wring together without lapping
So when are you adding the servos and controller what for making the grinder do grinder things all by itself?
The RC balancer should work fine, most likely could use some upgrade for the heavier grinding wheel. It's likely important that the balancer roller wheels remain parallel and planar vertical and parallel. May want to beefing up those threaded rod supports with something else. The RC turbine guys have some open source software for a dynamic balancer that shows the angel and amt of mass to add. Wonder how hard it would be to add an accelerometer on a wheel drive setup or directly on the grinder.