USB Height When Installing the Bench Grinder Mounting Set

[RickKrung]

I just bought a new "low speed" (1750rpm) bench grinder with aluminum oxide wheels, meant for sharpening HSS wood turning tools, etc., in the absence of a wet grinding system such as the Tormek.  My use will be for rough grinding of drills and other HSS tools before taking them to the Tormek for finish grinding and sharpening.  I am in the process of mounting the grinder and installing Tormek's BGM-100 Bench Grinder Mounting Set on a base board to allow use of the Tormek USB and related jigs. 

The design purpose and installation instructions for the BGM-100 seem to be focused exclusively on sharpening of wood turning tools, based on the manual that comes with the BGM-100: "Shaping and Sharpening Woodturning Tools on Your Bench Grinder".  On page 7 of the manual are a  couple of diagrams and some text showing and describing how to make a base board, with dimensions for the board based and horizontal distance of the back side of the mounting bracket from the vertical centerline of the grinder spindle.  There is an adjustable mounting :block" that allows varying the height of the XB-100 USB bracket from 56mm (2.2") to 89mm (3.5"), based on the wheel size of your bench grinder. 



There is, however, no information about how high to mount the bracket so the USB is at a good height relative to the grinding wheel, based on the size of the wheel.  This seems strange to me as the USB height, relative to the horizontal centerline of the wheel seems like it should matter and the adjustable block makes that possible.  So, why not guidance from Tormek on (approximately) where the USB should be relative the the grinder centerline?  Particularly since jigs other than those for woodturning tools may depend on that vertical relationship. 

Who among us has already installed a BGM-100 and what did you do in regard to setting the USB height? 

I ask more out of sheer curiosity, as I believe it will not matter in my case because I will be using a version of the modification of adding an adapter to hold an XB-100 in a vertical position which is adjustable away from the front horizontal USB mounting holes. This allows both the height and horizontal location of the USB to be varied, in relation to the centerline of the grind stone. 



I want the USB bar to be as close to horizontal as possible, but using the provided "adjustable block", there is not apparent method of ensuring the top and bottom are parallel. To satisfy my internal need, I used an adjustable parallel placed between the top and bottom brackets to ensure parallelism of the bracket surfaces.  Anything of suitable thickness could be used, it sure doesn't need to an adjustable parallel.



I set the height so the USB bar clears the front lower lip of the grinding wheel housing so that the bar could be set to within a couple mms of the wheel.  That height is 58.7mm (2.3").  The resulting height differential between the top of the USB bar and the horizontal centerline of the grinder is 28.5mm (1.235").  Beside the practical clearing of the wheel cover, it looks and feels good (right) (refer back to the second photo).  I'll have to wait to actually get it all installed and tried out with some drill bits to find out if it really is. 

Rick

[Grizz]

Knife grinders give some good advice for the paper wheel set up. you might get some information from them. I don't know if it will help you out any for the grinding wheels tho. I too got the same set up as you and still playing with the install. mine will be for the paper wheels tho.

http://knifegrinders.com.au/11Shop_PWsupport.htm

[RickKrung]

Knife grinders give some good advice for the paper wheel set up. you might get some information from them. I don't know if it will help you out any for the grinding wheels tho. I too got the same set up as you and still playing with the install. mine will be for the paper wheels tho.

http://knifegrinders.com.au/11Shop_PWsupport.htm

Thanks, Grizz,

I had not seen that page before, although I've had the applet for a while.  I have not had reason previously to look at it closely, but it is exactly what I need for this setup.  I'll re-examine my planned install with all that in mind, but I am sure it will work, one way or another. 

Rick

[Grizz]

I find it easier to measure the center lines by measuring from the shaft to the top or back side of the usb and subtracting 6 mm, since the usb is 12 mm.

[RickKrung]

I find it easier to measure the center lines by measuring from the shaft to the top or back side of the usb and subtracting 6 mm, since the usb is 12 mm.

Yes, I agree. 

I do this routinely, lately with the Tormek and related grinders, but for many years when locating holes in an existing part.  Measure the distance to the far side of the hole from an edge and the distance to the near side of the hole from that same edge.  Add 1/2 the hole diameter to the near side measurement and subtract the same from the far side measurement and average the two.  If they don't agree well, remeasure.

For more precise layout, I put in a gauge pin that snugly fits the hole and measure to the near and far sides of the pin.  This eliminates errors associated with width of the caliper tips and vagaries of hole wall variations.  This latter procedure is essentially what you said. 

Rick

[Ken S]

Rick, I don't know what the soon to arrive Multi Base 100 will bring. It may be a game changer, as may being able to grind accurately on the flats. These may or may not change your plans.

As far as being level, my gut feeling would be to accurately level the bench top and work up one level as a time, being certain to keep each step level. You may well end up keeping the entire set up more level than was originally planned. Knowing you, that is a goid thing. Just as small errors are cumulative, so also do smaller, tighter tolerances compound.

I would suggest you dedicate a separate usb to this operation and devise a simple inspection system.

Keep us posted.

Ken

[RickKrung]

Knife grinders give some good advice for the paper wheel set up. you might get some information from them. I don't know if it will help you out any for the grinding wheels tho. I too got the same set up as you and still playing with the install. mine will be for the paper wheels tho.

http://knifegrinders.com.au/11Shop_PWsupport.htm

After sitting at my bench, with the grinder and the combination of USB stuff, I don't think that applet is going to be usable for this setup.  The applet is designed for wheels rotating away from the USB, not into it.  My grinder is rotating towards the front, that is, into the the USB. 

If I turned the grinder around and switched the wheel guards left for right, the wheels would be rotating away.  In Wootz's photos, I noticed that the power cord is on the near side (toward the USB) and the power switch is on the far side.  It appears to me that turning the motor around and removing any guards is how he set up his machine(s) for use of the USB and the applet. 

Perhaps I should consider doing just that, as one of my primary uses will be rough grinding drills using the Tormek jig and it is designed for use on the horizontal USB on the front of the Tormek with the wheel turning away. 

For now, I will go forward with the planned installation without intent of using the applet and see how things work.  The grinder is brand new and is running very smoothly, so I am loathe to remove the wheels to get at the covers to switch them.  I have marked the shaft/nut/flange and wheel positions so I could likely get it all back together and retain that good balance, but it ain't broke now, so....

Rick

[RickKrung]

Ken,

Your reply came in while I was composing mine.  I have not considered how the new Multi Base may change how we grind, ie, on the side of wheels.  I was leaving that for after the diamond wheels and MB arrive and there is time to figure things out. 

As far as leveling goes, I will start with a base board onto which the grinder will bolt.  That will form the baseline for determining alignment of the USB in relation to the grinder.  It is much like leveling a lathe.  It doesn't need to be level to the world, just to itself (which is why they can be leveled even on a Naval vessel which is rarely level to the world). 

I have a 12mm dia. by 560mm long SS bar, from which USB legs have been taken, that I can lay across the front of the grinding wheels, resting on the guards.  I've determined that bar is essentially level with the shafts, with a very small slope of 0.0025mm over the width of the grinding wheels (25.4mm)(0.1%slope).  I doubt I can do any better aligning the USB to that bar, so that will be my reference.  It also serves as a reference for perpendicularity across the face of the wheels. 

A USB comes with the BGM-100, so there will be one dedicated to the bench grinder setup.  Only problem is I pirated the micro-adjust nut for another USB that came without one.

Rick

[cbwx34]

...
There is, however, no information about how high to mount the bracket so the USB is at a good height relative to the grinding wheel, based on the size of the wheel.  This seems strange to me as the USB height, relative to the horizontal centerline of the wheel seems like it should matter and the adjustable block makes that possible.  So, why not guidance from Tormek on (approximately) where the USB should be relative the the grinder centerline?  Particularly since jigs other than those for woodturning tools may depend on that vertical relationship. 
...

I could be mistaken, but I don't think the "USB height, relative to the horizontal centerline" matters.  From the manual part you posted, the adjustable block is there so you can set the height basically to give you room to work.  (I think, obviously you'd want the tool to contact above the centerline so you can see what you're doing, but whether the USB is above or below the centerline shouldn't matter).

After sitting at my bench, with the grinder and the combination of USB stuff, I don't think that applet is going to be usable for this setup.  The applet is designed for wheels rotating away from the USB, not into it.  My grinder is rotating towards the front, that is, into the the USB. 
...

The app, if you decide to use it, doesn't matter which direction the wheel is rotating.

If you're looking for a way to set the angle... my guess is measuring directly to the USB from the wheel (some version of Rich Colvin's calculator page) might be the route to take for some setups, with that you don't need to try and figure out a horizontal and vertical distance that the app requires.  For the other jigs... the TTS-100 should work, right?

Edit to add:  I "stole" a picture from Rich's page to illustrate what I'm thinking... I can take a setup where the USB is above the centerline, rotate it so it's below, and still set up the tool/jig to sharpen the same.  (How I'm picturing it anyway).

[Grizz]

the gage pin sounds like a good idea. will have to make me some.
it is important to level it to itself (very well put), and very important as you said to have the USB parallel to the wheels.  checking with the long bar is another great way to check the parallel of the USB.
since my grinder was a leather machine leather burnisher, I have no shields over the paper wheel. currently I have a block of wood 8" tall mounted so that I can use the top of the wheel going away. It doesn't seem stable enough so I will get a boat seat pedestal 7" high and bolt it down and mount the BGM-100. I have the MB-100 and the diamond wheels coming also, so it will be interesting to see what configurations we can muster up.

[Grizz]

Rick, I don't know what the soon to arrive Multi Base 100 will bring. It may be a game changer, as may being able to grind accurately on the flats. These may or may not change your plans.

As far as being level, my gut feeling would be to accurately level the bench top and work up one level as a time, being certain to keep each step level. You may well end up keeping the entire set up more level than was originally planned. Knowing you, that is a goid thing. Just as small errors are cumulative, so also do smaller, tighter tolerances compound.

I would suggest you dedicate a separate usb to this operation and devise a simple inspection system.

Keep us posted.

Ken

Get well soon Ken !

[Wyo6050]

This is timely as I just got my bench grinder setup over the weekend and was wondering he same questions regarding height.  I have the rikon slow speed 8" grinder and tried it but with the base wouldn't extend tall enough to be able to present the tool above the centerline on the wheel without having to extend it longer from the jig, so I added a piece of 3/4 plywood and it seems right.  I'd add another one so that the base isn't fully extend - so I want to add 1-1/2" in total. 

I'll post a pic when I can.

[Wyo6050]

Here are the pics of the setup- pictures corrected for size.

[cbwx34]

Not having used this configuration... I'm not sure how much it matters... but in your middle picture, it looks like the bar is sloping down slightly, in relation to the grinder?  (Comparing it to the label edge, and the guard on the wheel).

It also looks angled in the bottom picture (the other dimension)... but that may not matter as much?

Just thought I'd mention, in case it matters.  (Probably depends on what's being grinded also, I would guess).

[Grizz]

cb , are you trying to say its not level nor parallel to the main shaft ? lol......