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carlquib
04-23-2008, 01:44 AM
I got some grinding wheels from Little Machine Shop for a tool post grinder. They have an odd size 20 mm arbor hole. The problem is that the sides of the wheel aren't very parallel. I sent an inquiry to Saint-Gobain Abrasives and the response was as follows. "Thickness variation should not exceed .010. Beyond this variation, the product should be returned to Saint-Gobain via the distributor the product was brought from on a quality complaint. The sides can generally be reground to correct, but this process should always be done by the manufacturer." After talking to LMS they are telling me that they aren't comfortable replacing my out of spec wheels because the new ones will probably have the same problems. So my question is how do you regrind a wheel? I thought about chucking in soft jaws and then use a diamond to true the sides but that would make a huge grit mess on the lathe. Any suggestions that I am overlooking? Could I grind them on a surface grinder? Probably have to use a diamond wheel?

-brian

Evan
04-23-2008, 01:52 AM
You aren't supposed to mess with the sides of the wheel. I suppose though you could try using a chilled cast iron lap against them. Stand to one side of course. What is the wheel type?

Davek0974
04-23-2008, 07:51 AM
If the dealer wont change them in case the new ones are just as bad, I would raise that with saint-gobain. Sounds like a poor quality problem to me.

They have a duty to replace them if out of spec.

I would not mess with the sides of a wheel myself.

Dave

kap pullen
04-23-2008, 08:44 AM
You can machine a grinding wheel with a carbide tool in the lathe.
Run it slow with a heavy feed so you break the grains away
instead of cutting the tool.

Hold the wheel with your outside chuck jaws, with several layers
of index card, or shoe box material between the jaws and wheel.

Do not over tighten the chuck.

You will have to set the wheel with the same tir condition as on
the grinder, to take clean up the high spots on one side, reset,
and cut the other side parallel.

This will not do your lathe any good. Cover the ways, and slides,
and carefully clean when done.

This was done on a Bullard Vertical Boring Mill for wheels up to 36" dia
by 3" thick when I was just an apprentice boy.

A daimond dresser will also correct the problem.

When finished, hold the wheel on your finger, or a dowel, and tap it with a piece of hard wood or similar material.

A sharp ring indicates a good wheel, a dull thud indicates a crack.

If it has a crack, cover it with a rag, break it, and dispose of it.

Keep body parts clear of the line of fire, first time you start the wheel at grinder speeds.
-------------------------------------------------------------------------

Always use a wheel guard, and eye protection!
-------------------------------------------------------------------------

Realize that this can be a hazardous procedure, and do it at your own risk.
------------------------------------------------------------------------

This was standard procedure for opening wheel bores, and roughing special wheel shapes where I served my time.

Another option is BUY GOOD QUALITY WHEELS.

Kap

Carld
04-23-2008, 10:03 AM
I am with kap but I would make a mandrel to hold the wheel with a nut on the outside so I could flip the wheel to dress each side. I prefer to use a diamond dresser to do the job.

Have you contacted the manufacturer and told them about what Little Machine Shop said about returns? They may be very interested in that.

oldtiffie
04-23-2008, 12:36 PM
This exact same topic regarding the "as supplied" 80x10x20mm grinding wheel and problem with regard to the LMS tool-post grinder was discussed in the recent past.

I can't recall the original poster (OP) or the title of the thread else I'd search it out and post the link.

Hopefully, the OP or one of the other posters to that thread will recall it an post the link.

LastOldDog
04-23-2008, 07:45 PM
Hermann Schmidt sells a fine device for dressing the sides of wheels.

https://www.hermannschmidt.com/productcart/pc/viewPrd.asp?idcategory=15&idproduct=197

carlquib
04-23-2008, 09:42 PM
LMS is more than happy to refund me the cost of the wheels, that isn't the issue. The problem is the 20 mm arbor. I have looked in vain for a wheel that has a 20 mm hole, or larger. I actually did find some made by Dumore with a 1" bore, but at $89 a piece they are more than I will spend. I am going to make an add-on arbor for this grinder when I have time, but right now I just need to use what I have, so was looking for a fast solution to make the wheels that I have work. The wheel size is 80x10x20mm there are a range of grain sizes from 60 to 240 all are a K hardness.

Tiffie what size did your arbor end up being? I have found quite a few wheels in the 3 1/2 to 4 inch range, but all have 1/2 inch bores so that is the size I thought I would make my arbors when I get enough roun-to-its to actually make them.

-brian

wierdscience
04-23-2008, 10:26 PM
Any possibility of machining the arbor down to something common like 1/2 or 5/8" bore?Even if you do fix these wheels,you will have to go through the headache again when they are gone.

MSC carries several types of small TP grinder wheels,but most have a 1/2 bore IIRC.

carlquib
04-24-2008, 12:17 AM
No can't really machine the spindle without just making a new one. But the solution that tiffie used was to make a stub arbor that would mount on the existing arbor. I am going to do this when I have time. Right now I just need to get it put together so it will work.

-brian

Evan
04-24-2008, 01:22 AM
?? 1.25" bore wheels are standard issue in all sorts of sizes. I have wheels from 4 inch to 14 inch all with 1.25 arbor hole.

oldtiffie
04-24-2008, 01:37 AM
LMS is more than happy to refund me the cost of the wheels, that isn't the issue. The problem is the 20 mm arbor. I have looked in vain for a wheel that has a 20 mm hole, or larger. I actually did find some made by Dumore with a 1" bore, but at $89 a piece they are more than I will spend. I am going to make an add-on arbor for this grinder when I have time, but right now I just need to use what I have, so was looking for a fast solution to make the wheels that I have work. The wheel size is 80x10x20mm there are a range of grain sizes from 60 to 240 all are a K hardness.

Tiffie what size did your arbor end up being? I have found quite a few wheels in the 3 1/2 to 4 inch range, but all have 1/2 inch bores so that is the size I thought I would make my arbors when I get enough roun-to-its to actually make them.

-brian

Hi Brian.

The ones from LMS were OK - sort of. The problem was in the arbor set-up on the Tool-post grinder.

Look for grinding wheels under "Tool Room". These wheels have an internationally standard bore of 1 1/4" (31.75mm) and come with those plastic/nylon concentric sleeves that you use to "sleeve" the 1 1/4" bore down to 20mm (0.787").

I've tried contacting Sain Gobain (which owns Norton Abrasives) and on the net as well. But no success. The best thing is to go and see a SG/Norton distributor and have a look at the SB/N catalogue. The variations in size, type, grain, shape etc. is huge. What you want will be there.

If you are using the LMS TPG (which other than the arbor problem) is excellent, I'd suggest using a 100mm wheel as it will help get over the obstruction of the spindle bearing case.

I hope this helps.

macona
04-24-2008, 02:18 AM
My Tsugami tool grinder uses 20mm bore wheels. They have to be order specially. Seems they are common in Japan and I have found a supplier of diamond wheels in england.

The wheels on my grinder are made by Winter Superabrasives.

My diamond wheel is about shot so I am going to get to find how much they cost... Gee.. Cant wait...

oldtiffie
04-24-2008, 06:06 AM
Brian.

It seems that we have posted on this subject previously.

See the following:
http://bbs.homeshopmachinist.net/showpost.php?p=329674&postcount=5

http://bbs.homeshopmachinist.net/showpost.php?p=339587&postcount=11

Peter S
04-24-2008, 08:43 AM
It is common practise to true the sides of grinding wheels on surface and cylindrical grinders, mainly because the side of the wheel is sometimes used, but also because any runout is a bad thing when you want accurate and well-finished surfaces. On surface grinders, the whole wheel side can be relieved, leaving just a small area on the perimeter to cut. Even if there is no relief, it is not unusual to true the wheel sides, it only takes a few minutes to do.

On cylindrical grinders another method is to true the wheel sides, then angle the wheel head slightly, and dress the wheel face. This provides relief on one side of the wheel, often this is all that is required.

The truing is done with a diamond dresser fixed in whatever fashion is necessary to reach as far into the wheel side faces as possible. The wheel head is moved against the fixed diamond.

Having said this, the wheels we used were never running out much, it was a truing operation, not fixing some manufacturing fault. I have no idea what is actually going on here, so take care.

carlquib
04-24-2008, 11:32 AM
I don't think that a 4 inch wheel will fit inside the wheel guard. If I measured correctly 3.75 is about the max. Making a new wheel guard is possible and at some point I might make one of those to go with the spindle adapters. I did go to my local abrasives place, they have a large variety of manufacturers but she wasn't able to locate a wheel that had a whole that was 20mm or larger and a diameter of 3.75 or smaller in a type I wheel. I have found several companies that list wheels that are the right size, but when I went to their online stores I couldn't find the wheel in question. Which leads me to believe that they might be a special order.

Tiffie, where did you get your 100mm wheels? I haven't found any in that size here. Does a 100mm clear the wheel guard or did you just remove it?

I'm waiting for Roger at LMS to get back to me, after he has a chance to check and see if any of his current stock is better than what I already have. But in the mean time I wanted to come up with more alternatives if possible.

-brian

Evan
04-24-2008, 11:44 AM
My wife sells 100mm by 32mm bore diamond and CBN wheels. They aren't cheap and I can't make any promises for her but she usually gives a very good discount to forum members. She is away right now at a convention but if you can wait until next week I can tell you how to reach her. PM me if you are interested.

oldtiffie
04-24-2008, 08:20 PM
I don't think that a 4 inch wheel will fit inside the wheel guard. If I measured correctly 3.75 is about the max. Making a new wheel guard is possible and at some point I might make one of those to go with the spindle adapters. I did go to my local abrasives place, they have a large variety of manufacturers but she wasn't able to locate a wheel that had a whole that was 20mm or larger and a diameter of 3.75 or smaller in a type I wheel. I have found several companies that list wheels that are the right size, but when I went to their online stores I couldn't find the wheel in question. Which leads me to believe that they might be a special order.

Tiffie, where did you get your 100mm wheels? I haven't found any in that size here. Does a 100mm clear the wheel guard or did you just remove it?

I'm waiting for Roger at LMS to get back to me, after he has a chance to check and see if any of his current stock is better than what I already have. But in the mean time I wanted to come up with more alternatives if possible.

-brian
Hi Brian.

The info in the following links should help in that it should be self-explanatory. I have posted it previously. If you require any additional info just post a reply.

This is a very good TPG - but does need some "juggling" to fit to a lathe - but the small effort is worth the result.

I would suggest making new wheel mounting flanges to suit 1 1/4" bore for Tool Room wheels.I'd also suggest using 4" diam x 1 1/4" bore "cup" or "saucer" wheels" as are used on Tool & Cutter grinders so as to get both the OD and the "stand-out" to counter the protrusion of the spindle wheel mounting nut into the work-space. I'd also make a new wheel-guard both for personal safety and to contain/limit the distance that the inevitable grinding dust will travel.

Modify this sketch to suit:
http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG1.jpg

The following pics should clarify issues that need to be addressed:

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG2.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG3.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG4.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG5.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG6.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG7.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG8.jpg

http://i200.photobucket.com/albums/aa294/oldtiffie/Grinding_Wheels/TPG9.jpg

carlquib
04-25-2008, 02:28 AM
Thanks Tiffie, but it will probably be November before I get to that. The farming has started hot and heavy and I don't expect any real breaks 'till harvest is finished and it freezes for winter again. So many projects so little time. http://bbs.homeshopmachinist.net/images/icons/icon9.gif


-brian

oldtiffie
04-25-2008, 07:35 AM
It is common practise to true the sides of grinding wheels on surface and cylindrical grinders, mainly because the side of the wheel is sometimes used, but also because any runout is a bad thing when you want accurate and well-finished surfaces. On surface grinders, the whole wheel side can be relieved, leaving just a small area on the perimeter to cut. Even if there is no relief, it is not unusual to true the wheel sides, it only takes a few minutes to do.
............................................
.............................................
...............................................

.

Peter,
that post is one that is really needed - thanks - I have been meaning to mention side of wheel dressing and true-ing several times but either forgot or got side-tracked.

As you say, there is little side run-out of significance in a good quality wheel. All my wheels on the surface and tool & cutter grinders are Norton/Saint Cobain. Their balance as received is quite good as well.

I do dress the sides of my surface grinder wheels as soon as they are mounted on their own dedicated balancing hub and then possibly not at all there-after. Because there are no balancing hubs on the T&C grinder, the wheels are dressed all over to restore a reasonable balance every time they are mounted - the difference is quite significant.

The area of concern in this post and to which you indirectly referred is "side-wheel grinding" (aka "Side-wheeling").

As the wheel will be cutting on the land formed by dressing it is absolutely necessary that the grinder spindle be "trammed" to a plane that is both vertical/normal and parallel to the grinder table path.

This is just as a vertical mill spindle is trammed to the mill table - and for exactly the same reason/s.

I use an angle plate on the magnetic chuck. The plate is vertical and is "true-d" to the table path by a TDI registering on the angle plate and aligned to the table path by moving the angle plate just as a vice is moved on the mill.

The surface grinder spindle is trammed to the angle plate by moving the grinder spindle body "up-down" and "left-right" until there is no defection of the TDI on the angle plate as the spindle (to which the TDI is mounted/fixed) is rotated.

If the spindle is not "trammed" the effect on "side-wheeling" can be quite dramatic/significant.

If the spindle is tilted up or down but OK left-right, the wheel will cut a tilted/beveled surface instead of a vertical one.

If the spindle is tilted left or right but OK up-down, the wheel will produce a face that is elliptical with a vertical "long" axis.

If the wheel is tilted both up or down and left or right the surface will be an ellipse with a tilted "long" vertical axis.

This effect is not evident when surface grinding on the peripheral/round/curved surface of the wheel as it will still grind a flat horizontal surface.

carlquib
04-25-2008, 04:27 PM
That is interesting, I didn't know that it is common practice to dress the sides. I wonder if that is why I can't get the last little wave out of my ground surfaces. I have balanced my wheels but only on a static balancer. On a simple 6x12 manual grinder how would you set up to true the sides of the wheel? I was always under the impression that side truing was a no-no. I guess that on my grinder I would have to take the outside of the wheel guard off and then use the table to dress across the sides?

With a tenths indicator I can't pick up any variations in my surfaces, but when you look at the surface in the light you can see variations. Would that be because the sides aren't dressed.

-brian

Evan
04-25-2008, 05:26 PM
The eye can see variations below the sub micron level depending on what sort of variation it is. Vibration from unbalance can certainly cause that sort of variation which changes the quality of the reflected light. It's even possible to see variation at the atomic level since that is what color is.

oldtiffie
04-25-2008, 10:51 PM
That is interesting, I didn't know that it is common practice to dress the sides. I wonder if that is why I can't get the last little wave out of my ground surfaces. I have balanced my wheels but only on a static balancer. On a simple 6x12 manual grinder how would you set up to true the sides of the wheel? I was always under the impression that side truing was a no-no. I guess that on my grinder I would have to take the outside of the wheel guard off and then use the table to dress across the sides?

With a tenths indicator I can't pick up any variations in my surfaces, but when you look at the surface in the light you can see variations. Would that be because the sides aren't dressed.

-brian

HI Brian.

Evan's post was correct.

That you can't pick it up with a tenth DI is not surprising either but other that "looks" the surface finish is OK.

To side dress the wheel, put a diamond dresser stick in a small vice on your magnetic chuck and just "dress away" until all the "Grey" surface turns white.

Wheel and surface finish are generally reliant on the "sharpness" and correct grade and type of wheel as well as "balance".

Balance is in two parts which act in concert:
- the dynamic balance of the motor rotating assembly as a whole; and
- the static balancing of the wheel and the hub that it is mounted on all of which in turn is located on and fixed to the motor/dynamically balanced assembly.

The static wheel balancing works very well if done correctly.

It is an iterative process.

First, balance the wheel on the balancing hub, mount the hub and dress the wheel so that all of the "grey" surface is removed and all you have left is "pure white".

Now re-check the static balance.

If all is OK you are set to go - finished.

If not, with the "heavy" part of the wheel "down" release the grip of the flanges on the wheel. The wheel should "drop to the bottom" and be eccentric. Clamp the wheel, re-balance it and re-dress it, and check the balance again. If all is OK, no further action is needed.

A note on dressing the peripheral surface of the wheel.

After you take a pass with the dresser, lightly put your fore-finger "print" upward under the dressed surface. You will feel the imperfections in terms of "blunt" and "sharp" as well as dressed and not-dressed.

A word or two of caution is in order here - very much so - as if you get it wrong you are going to have considerably less finger and considerably more pain. A grinder burn is most inconvenient!!!.

Just make sure that there is ample room under the wheel. Keep on the periphery only and you should not get burned.

Put your finger on the "corner" of the wheel and you almost certainly will get burned.

If the dynamic balance of the motor and shaft is not OK, you may well have to have it re-balanced by a specialist. But it has to be a long way "out" to be of real practical concern. Failed or failing bearings can have a similar effect as can replacement bearings on the rotor.

Chances are that your grinder is quite OK for practical purposes. If that is the case - leave it alone.

Grinders are classic cases for the "if it ain't busted, don't fix it" approach.

Peter S
04-27-2008, 09:39 PM
Brian,

I guess the main reason we dressed the wheel sides on the surface grinders was because we needed them true for grinding the sides of recesses etc, and on a cylindrical grinder you are often using the wheel side to grind a shoulder.

On the surface grinder, the diamond was mounted in a steel block and for normal dressing the block sat on the magnet. For side dressing you could hold the steel block in a grinding vice stuck to the magnet. You didn't have to remove the guards, there was plenty of room to reach the wheel sides. The diamond can be angled to help it fit into the space available. We used the rise and fall of the wheel, with the table locked, to dress the wheel sides. As I mentioned earlier, for grinding with the side of the wheel, you would relieve it, so leaving a small margin on the corner of the wheel to do the actual side grinding. Only minimal side grinding was ever done, usually it meant just cleaning up surfaces after hardening. It is easy to get overheating and cracking doing this, only a few 'tenths" are removed at a time.

I think on the cylindrical grinder we had an attachment for dressing the wheel sides (for normal dressing the diamond was permantly fixed in a holder on the tailstock). It was a base that clamped to the grinder table, with a post and an adjustable clamp for holding a long rod with a diamond on the end. You could adjust and lock the long rod to give the reach required.

I should add, all our wheels were only static balanced. The grinders were substantial machines in good order and using coolant. I guess it is possible a light or small grinder, possibly a bit tired in the spindle, with no coolant is never going to give perfect results.

All of the above was done on substantial toolroom machinery, with good sized wheels. There is always care needed with these machines, please don't rush ahead on the strength of my comments without thinking it through.

One more thing, we had a special grinder which only used the sides of the wheels. This was a Coventry Tool and Die gauge grinder, made specifically for grinding "Go, No-Go" gauges made from hardened plate. The wheels were very fine grit, about 400mm/16" diameter x 19mm/ 3/4" wide and were specially made with heavily relieved sides. So the only dressing required was to the small margin on the wheel side, the circumference of the wheel was never used. Sizing was done with slip gauges.

oldtiffie
04-27-2008, 11:45 PM
I agree with everything that Peter S said - a very good informative post.

Grinding wheel ''dressing" is not just about "balancing". It is very much about keeping the wheel "sharp", maximising accuracy and minimising "rub" and "burn".

My previous comments regarding "tramming" the wheel spindle are very relevant in the context of side-grinding to ensure that the sides/vertical surfaces ground with "side-wheeling" are truly flat, vertical and, where applicable, parallel - often within very high orders of required accuracy.

If slip-guages are not available then consider buying and using an "Adjustable Parallel Set" as at:
http://littlemachineshop.com/products/product_view.php?ProductID=2552&category=1962771978

They are precision tools and require a good "feel". They work very well indeed with a good micrometer to guage "inside" measurements with parallel sides.

But do not be "heavy-handed" else you may end up using them as "fox/folding" wedges (two identical wedges back-to-back) as considerable forces can be exerted.

Peter S
04-28-2008, 01:47 AM
Brian,

Old Tiffie's raises a point I was taking for granted, but maybe needs to be stated - the wheel is usually re-dressed every time you use a grinder, and often during a job, e.g. just before the final cuts, or when the wheel starts to load up or show obvious uneven wear. The dressing would be quite fine, say taking a 'thou' off as a final dressing, and the diamond is usually on an angle, see a dressing handbook. It is years since I used a grinder, hopefully my memories are still correct :)

We used to grind some really difficult tool steels which required constant dressing because of wheel loading, and smaller surface grinders couldn't handle this sort of work at all. Other materials like sprayed-on hard facing used to wear more off the wheel than they took off the job! Sometimes the wheel choice may not have been perfect, but you can't be changing out wheels all the time.