Problem mounting the BGM100 to match my Tormek

[RandyHeinemann]

I use my Tormek SuperGrind 2000 with the SVD186 and a diamond wheel to sharpen my bowl gouges. I recently puchased an 8" set of CBN wheels mounted on a slow-speed grinder and a BGM-100. The reason I bought the BGM-100 was to be sure that I would match the grind from my Tormek with the 8" grinder. I have installed the BGM-100 on a plywood platform and have attempted to follow the instructions in the manual provided with the BGM-100. Unfortunately the result was that there isn't a direct match of angles between the Tormek and the 8" grinder/BGM-100. I use the TTS-100 to set both the Tormek and the 8" grinding wheels up, but they don't yield the same result. I assume it has something to with the mounting of the BGM-100 in relation to the 8" grinding wheels but I don't know what to change to correct the problem since I believe I followed Tormek's instructions when mounting the BGM-100. Does anyone know what the solution is?

[RickKrung]

Curious.  Sure seems like following the instructions should work.  Some pictures of your setup would be helpful for others to understand exactly what that setup is like. 

I mounted the BGM-100 on an 8" bench grinder and found it too limiting to have only horizontal movement/adjustment.  One could say I had been spoiled by having an FVB on my Tormek.  So, I added the FVB , giving me both horizontal and vertical adjustments.  I get it that setups for woodturning tools are designed for use on the Tormeks, both 8" and 10" diameters, so it makes sense it ought to work for a similar setup for the bench grinder.  Also, for sure, my uses are close to the wheel as I don't sharpen woodturning tools, but it is something to consider. 

Rick

[RichColvin]

I also find the FVB makes a big difference 

[RandyHeinemann]

It seems I can't figure out how to attach pictures.

[RandyHeinemann]

You cannot view this attachment.You cannot view this attachment. 

Two pics . . .One is the overall grinder installation with the BMG-100 installed, the other showing (not very well) that the resulting grind will not be exactly as it is off my Tormek. The pic is supposed to show  that the black marker I used to color the bevel isn't rubbing off over the entire bevel, thus changing the angle slightly. The marker was rubbed off near the cutting edge but not toward the bottom of the bevel. This will change the angle slightly, admittedly probably not significantly. However, the whole point, based on the BMG's description, is to allow the user to create exactly the same bevel on both the Tormek and the 8" grinder using the BMG as a tool rest.

The instructions in the BMG-100 manual are really not completely clear on exactly where to mount the base, leaving some things to, more or less, "deduction".

[Dutchman]

I use my Tormek SuperGrind 2000 with the SVD186 and a diamond wheel ...
... snip
I recently puchased an 8" set of CBN wheels mounted on a slow-speed grinder
... snip

I assume the diamond-stone on the Supergrind-2000 has a diameter of 250mm.
On the other hand, the diameter of the stone on the slowspeed-grinder is mentioned to be 8".
Then you will have to adjust the distance from the USB to the stone to get the same grinding angle.

If the stones have the same diameter AND the distance from the USB to the stone is the same in both cases then the grinding angle should be the same in both cases.

[Ken S]

My thoughts are like Dutchman's. Either the 250mm Tormek wheel or the eight inch Wheels will produce acceptably sharp edges; however, the two edges will not be identical. Using two different wheel diameters moves resharpening slightly into reshaping. If you first grind with the 250 mm wheel, a short test spin with the eight inch wheel and black marker should remove the marker only in the center of the 250mm bevel. If this mark is not centered, you can shim either the BGM or the grinder to make it so.

If your test mark is centered, the diameter difference is the problem. If so, is the difference visually unpleasing or does it effect the sharpness of your tools? Ideally, your wheels should be the same diameter; however, if your diamond wheel is the 600 grit fine wheel, I would do the heavy grinding with your coarser eight inch wheel. I occasionally do this with my eight inch 46 grit Norton 3X wheel. Then I finish with a 250mm wheel.

If any of the replies do not solve your problem, please keep posting. We will solve the problem.

Ken

[RandyHeinemann]

Normally I would agree with the wheel diameter argument and, I would guess that the 8" wheel would produce a bevel that is a tiny bit more concave. However, the reason I believed differently is a video online which I think is by either Tormek or Nick Agar which actually demonstrates the compatibility of the two systems for sharpening gouges using both the BGM-100 as the tool rest, SVD-186 to hold the gouge, and finally the TTS-100 to set the distance.The result of that video is that you can move freely back and forth and get the same result. In practice, for me at least, since I already use my Tormek to maintain the edge on my gouges (and other turning tools), the Rikon grinder with 8" wheels would almost always be used to change a profile, etc. In fact the 2 wheels on the Rikon 8" are 80 grit and and 180 grit with the coarsest grit of my Tormek diamond wheels is 300 with the 600 grit diamond wheel being the one I use to touch up gouges while turning. I am really just trying to be sure that, in fact, the new grinder/wheels/BGM-100 is actually mounted correctly. It's been a little more complicated and less easy than I thought it would  be.

[RandyHeinemann]

I just happened to see the section of an October, 2022 post Rich Colvin quoted below:

"Last note, if you are looking to change the shape of the tool, consider getting the BGM-100 Bench Grinder Mounting Set.  That will allow you to use your bench grinder's fast cutting action to quickly set the shape using the same setup (USB and Grinding Jig) you will use on the Tormek.  Then you can move back to the Tormek and sharpen the new shape.  I use that approach often.  Only caveat is to be slow on the high-speed grinder if you are sharpening tools which are not high speed steel.  You don't want to remove the temper from the steel."

This would indicate that my original expectation is correct. However, since the wheel diameter on the Tormek machine versus the 8" grinder is different, does this post mean the actual result won't be exact when moved between the two setups? Maybe the basic profile is the same but the final sharpening would change the actual profile slightly when done on the Tormek?

[tgbto]

Hi Randy,

There is exactly zero chance that you'll get the exact same profile on 10" and 8" wheels. The BGM manual mentions using it with 10"/8"/6" wheels that account for almost 100% of the bench grinding market. If you need more convincing, think 3" wheel and you'll see that concavity will ensure you get a different grind.


Using the TTS ensures that the angle is the same at the point in between the points of contact of the rollers and the wheel.

The actual setup of the BGM-100 matters not so much for angles as they which depend solely on projection distance, wheel radius, and USB height. The TTS allows you to manage the USB height when the projection is preset, and uses the two rollers to approximate the tangent to the wheel.

The setup matters more for making sure you can actually work without hitting anything with the jig (see the section about the riser block, the height of which is left TBD). Finally, a difference in the 'a' distance will be compensated by a different USB "height" setting.

You just have to make sure that the USB axis (or BGM baseplate) and grinder axis are parallel, or else the angle will change (slightly) as you move the jig along the USB.

The only way I see to get the exact same results is to use a brand new T-4 SG wheel (or diamond wheel), and a brand new grinding wheel of the exact same diameter on your bench grinder.

[EDIT] ... whatever difference you get will be minimal, and grinding on the 8" bench grinder initially will save you a lot of time even if there is a tiny bit of reshaping to do on the 10" Tormek [/EDIT]

Cheers !

[RichColvin]

I follow the process outlined below for my lathe tools, and many others also (especially if the cutting metal is HSS).

You cannot view this attachment.

For the shaping of a tool, if a lot needs to be done, then I use a bench grinder with the BGM-100 to do that work.  How much does the grindstone's diameter matter?  The picture below shows a side view of a ½" high tool (the gray part) being ground.  The first grinding was using a 6" wheel (the red part), and then with a 10" wheel (the tan part).

You cannot view this attachment.

As you can see, there is not much difference in reality, and an 8" bench grinder would have even less.  The red part barely peeks our from behind the tan part.  And over time, that concavity will be ground down (if I don't do it on the first sharpening).

What I found with the BGM-100 is what Rick seems to have also found:  it is not easy to use some of the jigs on the bench grinder.  The angle just never seems right.  What I (and it seems Rick also) found is that using a FVB with the BGM made the whole process a lot easier.

What I did not find is that the overall shape of the tool was different when using the bench grinder with a BGM-100 than it is on the Tormek.  I suspect that the problem being experienced is more to do with how to use the jig and properly rotate the tool in the jig. 

The bench grinder's 1" wide grindstone also made this more difficult.  I had to slide the jig on the USB more to hit all the parts of the ground surface.

Hope that helps.

[RandyHeinemann]

When Tormek made diamond wheels available, I bought both the 300 and 600 grits. I mostly use the 600 grit wheel for maintenance of my bowl gouges and scrapers. The setup is quick, completely repeatable, and, with the 600 grit diamond wheel, the edge is sharp and more refined than the surface resulting from what most turners use to sharpen; anywhere from 120 - 220 grit wheels.

My new Rikon 8" grinder is equipped with CBN wheels, both 1 1/2" wide; one 80 grit and one 180 grit. Having tested the 180 grit on my scrapers with the SVD-110 on the BGM-100, the result was excellent and fast; a nice burr on the edge (although I tend to re-create the burr by hand later. However, I was able to get the exact bottom angle on my NR scrapers that I wanted. I suspect the purchase of an 80 grit wheel was likely a waste as the result was achieved very fast with the 180 grit. However, with the 80 and 180 grit CBN's and the 300 and 600 diamonds I was going for a range of grits.

My new grinder will have a second tool rest; the Lee Valley (Veritas) rest which I'm now mounting. Between that and the BGM I suspect I can handle almost anything I need to shape or sharpen.

Initially my expectations were based on what I saw on YouTube from Tormek staff and Nick Agar concerning repeatability between the 8" wheel with a BFM and the Tormek. In retrospect those videos created unrealistic expectations. I would agree that the way I have my BGM mounted in relation to the 180 grit wheel yields a result that is very close to what I would get from the Tormek with my gouge jig and the diamond wheel; close enough that finishing the sharpening on the Tormek would yield exactly what I want. I would also agree that it may well be impossible to get the same exact profile on an 8" versus a 10" wheel. Because all the wheels are either diamond or CBN, reduction in diameter will likely never be a problem for me so once something is set and I can leave it setup it should stay correct.

Since I did buy the Rikon for easy rough shaping and possibly some additional rough work with my bench chisels I think they will serve my needs. Mostly this post was prompted by my interest in determining whether I had actually mounted the BGM with my Rikon grinder correctly. I think I'm satisfied that I have mounted it so that it will function as I intended.

But, anyway, thanks for all the feedback. It has been very helpful.