Wobbly wheels on my bench grinder
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- เผยแพร่เมื่อ 8 ธ.ค. 2020
- And how I almost fixed them. I got more wheel wobble than I expected on my new Draper GD825L bench grinder. I tried two ways of fixing it, but did not have as much success as I had hoped.
I returned to this topic in April 2021, see • Wobbly wheels on my be... - วิทยาศาสตร์และเทคโนโลยี
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See also my later th-cam.com/video/rVKHdoRmV9g/w-d-xo.html and the comments below it for other suggestions..
I have been down this road myself. All your problems are where the plate meets the grinder shaft step, as you said in the beginning. The shaft fit on the arbor is less than ideal. The only way you will get it even close is to buy a grinding wheel with a 32mm center hole, then make an arbor that fits neatly on the shaft and neatly inside the wheel at the full depth of the wheel. Then you will get the length of the shaft / arbor supporting the wheel. Only then you might be close to getting a balanced grinder. Hope this helps, Cheers
As usual in your series very thought provoking. I really enjoy the 'forensic' analysis and attempts at making a silk purse.....Of course in the final analysis and as you said the fundamental issue is the abutment being ridiculously small in diameter. The swash readings are + to - (total/2)
In practice we do trim the grinding wheel as you said but not on the side as this can be dangerous however I do trim up on my 'domestic' machine! however true industrial machines run true so its just the error in the wheel being corrected.
Just to let you know re one of my posts about the MW14 quill tracking out from the stop to full extension. Warco have offered to send me a new head Warco do endeavour to support their products. Look forward to your next investigation.
Thanks. I feel your pain.
Great video. Love your stuff. Really thought provoking. I too have the same issue and I too believe it to be an issue with the tine lip and the ill fitting plates. I'm looking at having a short sleeve made that fits over the lip and is part of the plate itself. I put CBN wheels on and the issue is the same as we know they are true when made.
I'm late to this thread but I had a similar experience with the Axminster 8" slow grinder, except my problem was the grinding wheels. When I first switched it on it wasn't bolted down & it nearly fell off the bench, I mean that literally because I had to unplug it to stop it as I daren't go near it!!!! I bolted it down to a purpose made heavy wooden stand & I'm pretty sure that the bolts removed the vibrations ability to go anywhere so it sounded like the wheels were going to disintegrate any second. With CBN wheels though, it ran OK. As sent out by Axminster, it was an absolute danger to life & limb & this is a full UK company sending out untested rubbish. Like Samuels, my wheels wobbled side to side so couldn't be dressed. My view is, unless you're buying something from a real manufacturer that makes real machinery where THEY monitor quality control, everything else is just cheap Chinese rubbish with a lowly brand name. Whether that name is Amadeal, Warco, Draper, Stanley, Scheppach or any other one you can think of, it will all be untouched by UK hands & straight off the ship to your door. You'll then find people reviewing this rubbish & playing down the defects as no one wants to admit they picked the £400 branded version over £150 unbranded version & they were both equally garbage!!!
I would make a new plate that fits the shaft better. Then you'll have more "purchase" against the very small shoulder. I had the same problem with mine. How loose that plate is on the shaft, it's kind of acting like a ball and socket and when you remove it then put it back, even if clocked the same, the will be no repeatability. That's only my .02 cents on the matter. Good luck sir.
Yes I think you're right. We need a thicker plate to engage better with the shaft, rather than the shoulder, but we also need to avoid moving the wheel outboard much, or we run out of thread on the nut.
It doesn't need to be thicker, it needs to be a much closer diametral fit on the shaft.
Also, any tiny burr on that tiny shoulder will make it absolutely impossible to get consistent results.
Oh and your washer plates are die cast, not stamped
I thought the problem lies in the very small lip on the shaft, which fails to locate the back plate at rightangles to the shaft axis. There is no scope for improving that lip in situ. It has been suggested off youtube that one solution would be to stop relying upon that lip entirely. Machine a bush that is a tight fit to the shaft, and that is long enough to align itself to the axis of the shaft, let it use the lip just as a back stop, and then locate the back plate on the new bush. The only problem with that is that it would move the grinding wheel 20mm say outboard, requiring rejigging of the wheel guards and also risking running out of thread on the shaft for the nut to engage with.
Oh!
I mentioned this in a reply, sorry I didn't read this comment before posting.
"An additional thought!
You could machine a new holding plate with the sleeve from a single piece of metal, to sit around the lip by just 5mm”
Harold Hall addresses this in his "Tool and Cutter Sharpening" book. I did what he suggests, making the busing. Mine only extends 1mm past the factory "lip" and there's about 6mm of the bushing pressed onto the larger diameter of the shaft.
Make a sleeve that will slide over that tiny shaft step and go clear back to the motor bearing inner race that the motor shaft goes thru and have the sleeve terminate at the step in the shaft.
Then turn yourself a nice arbor collar that fits the shaft nice that has the inner washer as part of your collar and use stones with 1” center holes to fit your turned collar OD with a second turned outter washer to press against the outer stone area
I had a similar problem, this is the reason I searched on youtube and found your channel, I have a Hilka model, but on fitting new draper wheels, I found that if as I tightened the wheels up I had the same wobble, as the clamp plates on mine are in fact pressed steel, rather than your cast items, I found that if you can adjust the run out by manipulating the wheel, (whilst spinning it by hand), as your tightening up the nut on the end of the shaft, I couold get it to run true by eye. Hope this is not too late for this to try and help you, best regards, Dave
Thanks. I've tried this and I think it does make some difference, but with my wheels it doesn't completely solve the problem. I suppose the principle is that if both the wheel and the clamp plate have some runout, then by careful adjustment one can get them to cancel each other out to some extent.
@@samuelfielder I think because you have the thicker casting flanges, it would be harder to get the wheels running true, with mine being pressed steel allows a certain amount of movement. Every video I've seeen on this has been the same, these are very crude machines, I used to build prescision grinding machines, and the flanges were on ground tapers and the runout was just microns, if that, and that was just by clamping the wheels up. The only runout was in the periphery, none side to side. Apart from re-engineering the spindles, I can't see a solution.
I just bought this exact same draper 8 inch bench grinder and for anyone worried I can say mine is very smooth and no wobble. Hence I wD surprised to see these videos. I think this is just a balance issue with the grinding stones and a case of bad luck. Using a bench grinder not bolted to anything solid could also add to the potential for vibration. I am going to mount mine to a bench grinder stand and use it primarily for wire wheel and metal polishing purposes.
Just bought this model. Man I wish I'd seen this video beforehand, would have saved me wasting my money! Having made similar attempts at rectifying this obvious design flaw I think Adrian Britton's solution should do the job. Just eliminate the useless casted flange entirely and machine a tight fitting backing plate that just uses the lip as a backstop. So long as the plate fits snug to the spindle and is made to protrude no further than the supplied flange I think it should be fine.
Yes. It is also the case that not all wheels are themselves flat and hence free of wobble. So part of the observed wobble is due to my wheels. I had wondered about using a diamond in a gradually expanding radius from the centre to true the side of my wheel. Not quite obvious how to do that. I feel I shouldn't have to. What I thought was a good quality Norton wheel turned out not to be flat.
Joe Pie has a video of a lathe modification you can make to your chuck that will allow you to get very accurate parallel surfaces on such items as you are dealing with in this video.
Thanks. Which one is that?
Proper way to fix is to glue the part on the shaft with epoxy, then true it with the grinder itself running, then no more problems.
Yes, glue it correctly, and also wind a thin sticky faceplate for a tight nozzle. But I wouldn't recommend a corner grinder, it's very rough and also dangerous. It is better to use a Dremel type machine with a diamond cylinder and sharpen with a stop.
And the author also forgot that in addition to the end runout, there is a radial runout and, as a rule, it gives more vibrations. Therefore, it is necessary to remove the imbalance in weight. There are many videos on TH-cam. Simply put, you need to find a lighter half and glue a piece of lead onto the epoxy. The weight of the lead must be selected until the imbalance disappears.
Hi Samuel. I have had this exact problem since I first purchased my Bench Grinder 25years ago!!! I have attacked the issue a few times over the journey but to no avail until today........On dis-assembling again i actually noticed that the nuts that do up on the shaft to hold the wheels in place were obviously tapped by someone who was asleep because they tapped on an angle which make them out of square when they are screwed onto the shaft which in turn puts angular pressure on the washers that clamp the grinding wheel.
I simply replaced the nuts with perfectly true ones and oh my god my marathon of a riddle was instantly solved!!!
Hope this helps you?
Thanks, that's something else that I should check. I did fix mine by other means in the end see th-cam.com/video/rVKHdoRmV9g/w-d-xo.html .
@@samuelfielder another great video. Think I'll check out the balance of my wheels too.
I have been having the same battle.
180 pounds... You got ripped.. That is the exact grinder that ryobi have for sale in Australia for under $100 aud so at the price you paid works to roughly $320 aud..
You need a to create a shaft spacer adaptor to slide over the shaft which then locates up againt the shaft bearing and then up against the face of the grinding wheel. Common issue on bench grinders
I will have to deal with the same issue. The small height of that lip on the shaft is a big issue on my grinder. The discs that hold on the stone are stamped metal. So I really have my work cut out for me. You will have to dress the sides and the front of the stones. But most of all, balance the stones due to their inherent problem of having differant densities while being made.
Did you ever CK the run out on the step of the tiny face of that shaft itself? After all that's where it all starts
Too small for the spherical point on the end of my DTI.
I am in the same situation, and a little worst. I am on my way to buy anotner bench grinder (more expensive) but I am scared that the new one will be the same. I am dressing my old grinder for two days and still there is wobbling. I am done.
I did some more work on this th-cam.com/video/rVKHdoRmV9g/w-d-xo.html . However, I think the most important thing to do first is to balance the wheel. I now think the best way of balancing the wheel is to use an off-balance flange or washer that can be adjusted to neutralise any off-balance in the wheel itself. See also th-cam.com/video/Lci46fahHKc/w-d-xo.html . Only when the wheel is balanced worry about problems in the grinder itself.
That washer looks like cheap cast stuff not pressed
Hi man
I thought you was crazy to worry about the run out all the way through that video, right up until you showed the grinder running at the end.
That noise it made on down spin is concerning, I would be tempted to make a new holding plate on the lathe and make it run true.
I think the noise as it runs down is just a resonance at a particular shaft RPM, probably nothing to worry about. But one can worry about what's going on all the time when the grinder is runnnig at full speed. I did think about machining a new plate from scratch, but doubt if it would be any more accurate than the plate I now have. I think the problem is the very small lip on the shaft which may prevent proper alignment.
If you made a new tight fitted steel holding plate it could be made to run true. Plus if the small lip is a problem, Then why not lathe a steel sleeve/washer to slot over the axle lip, that would solve it.
I thought that the noise on the grinder during run down was a vibration / shimmy of the granite disc on the axle. If this is right and not addressed, then it could eventually damage the bearings and gears of the motor.
FIRST THING IS TO BALANCE THE WHEEL!!!!!!!!!!.......same as you do on a surface grinder.......That stops that vibration in its tracks...then dress it...........trust me. I use 4 grinders with 8 different wheels......look on the "Tube" for how to build a balancing ring OR buy one on eBay......or build a mandrel and "Drill balance" it..........plenty of you tubes on it.....mainly under "balancing surface grinder wheels"
Cheers from Aus.....Davo
I had some limited success by making a washer/ sleeve combination .
I have a similar problem and I think I am going to take the grinder in the garden and dress the wheel true with a diamond.
Dressing the circumference - the normal area to be dressed - is necessary and useful, but it won't remove the side to side wheel wobble. I suppose you could dress the whole sides of the wheeel, but some people advise against this on safety grounds. Presumably they think dressing the sides will weaken the wheel and increase the chance of it exploding.
@@samuelfielder I don’t see a problem with dressing the sides, it will true them up and I think there is plenty of thickness to the wheel
I do not understand English, perhaps the author explained why he did not grind the side on the shaft of the sharpener itself, but since the cups were machined in parallel, the probable cause was an uneven protrusion on the sharpener axis.
You were unfortunate. I've bought a PELA benchgrinder, unboxed it "yesterday". It ran well, made a nice humming, standing still on its rubber feet on the floor.
At the time 04:20 You use a cast surface as reference. That can't be the best.
Time 04:50. What are You doing? Did You turn that outer surface in the earlier moment? If not, that ought to be really unknown.
Not being an expert I almost think about making a new plate from raw stock.
But, as You say, poor discs are not easy to correct for.
At 04:20 I do use a cast surface as a reference, because there is no machined surface on the plate to use. But my reasoning was that since the plate does not grip the shaft closely it can easily align to the surfaces I am machining. One has to start somewhere. There is a ring of large diameter on one side of the plate, and ring of smaller diameter (which butts up against the lip on the shaft) on the other side. So I used the latter as a reference to machine the large ring, and then turned the plate over and used the now- machined large ring as a reference to machine the small ring. So then both rings are in parallel planes. But because of the initial cast reference, those planes may not be exactly at rightangles to the axis of the hole through the middle of this plate. But that doesn't matter since that hole is a loose fit on the shaft. The plate surfaces will align to the shaft lip anyway.
I did think about machining a new plate from scratch, but doubt if it would be any more accurate than the plate I now have. I think the problem is the very small lip on the shaft which may prevent proper alignment.
@@samuelfielder Yes, that minimal lip is a suspect. I suppose a mandrel would have been useful in order to check that disc up.
You Piesz... uses a technic where he used the talstock to press the object towards the chuck. Then the flat surfaces of the disc ought be useful.
Joe Piesz....
@@Stefan_Boerjesson Yes, I've seen Joe Pie's technique. But I made an arbor instead to hold the plate for the first turning operation, which IK thought to be ok.
@@samuelfielder Yes. I just spotted that, Time 05:00. That should ensure parallellism of the 2 surfaces and the surfaces being square to the axle. I missed that looking the first time.
This guy had the same problem and resolved it with a special spacer assembly which can be purchased. -th-cam.com/video/dHx0uItIvVA/w-d-xo.html - I hope this can rectufy your problem for you.
Thanks, that's another aspect of it: the nut face not being true. He does say in a comment that it didn't work well for him using all-abrasive wheels (as opposed toi the metal cbn wheels he got to work). Whether my nut faces are off I don't know. His grinder at least has much fatter flanges on the spindle than mine.
If he had followed the instructions in the Utube video "Bench grinder Setup. Part one" then his problem would have been solved without all this fuss!
Prooves you can't make chicken salad from chicken crap!!!,
little obsessed aren't we lol
The only issue here is an individual with no understanding of what he’s trying to achieve with a bench grinder? He’s got a severe case of OCD? I have never watched somebody with a complete lack of understanding of what the fxxx he is doing? The only wobble here is in his mind? He is in need of a reality check? This has been an episode of someone about to hit a complete mental breakdown!!! If anyone decides this is the way forward with a Bench Grinder? They should seek immediate psychiatric advice? Course you’ll need it!!! Totally over the top!!! 😀😀😀.
sorry, this is the first dislike, the video is completely junk... it just you try to figure out what the issue is and neither at the end of it it succeed
The video is exactly what is says in the title - it's about the wobbly wheels on his bench grinder, it never claims to offer a solution, it shows a process. Whiny prick.