Helplessness. Tormek BGM-100 does not work on different Stonediameters :(

[fritz Mayer]

Hello, please help me to use the BGM-100.
After I have been using the Tormek T-8 for over one year, I bought the BGM-100 for my new  bench grinder.

Now I have big problem, that the (angle)result on the Bench Grinder is not the same as on the Tormek T-8
What could be the reason? Is it a problem that both have diffent wheel-diameter (Tormek=250 and bench grinder has 200mm on stone diameter)?
Or is my installation from the bgm-100 wrong?

And the bad results are always the same, it does not matter if I use hole ,A' or ,B'.
The same shit is by the use of SVD-186, or I change the height of the wood-block☹

Please help me to clear this situation! Thanks a lot!!
regards Fritz Mayer from Austria


Now here are photos from the problem.

Pic1: I use the hole B on the Tormek to adjust the usb
Pic2: After I marked the bevel with permanent marker, I rotate the wheel to see the result
Pic3: Same in a bigger resolution
Pic4: The result is a parallel clear area. Which mean all is right adjusted
Pic5: Now set the TTS-100 on  my bench grinder. Also hole ,B'. Stonediameter is 200mm
Pic6: It's hard to photograpf, but the bevel has a gap, and it is not full on stone
Pic7: On the marker we can see better the bad result
Pic8: Here you can see the distance b with 35mm

[fritz Mayer]

Pic9: Here you can see the whole solution

[Jan]

Mr. Mayer welcome to the forum. 

As you know wheel grinding results in slightly hollow shape of the grind. Smaller grind stone causes larger hollow grinding. Thanks the hollow shape of the grind, the edge angle slightly changes its size with distance from the tip of the tool.

The TTS 100 sets the edge angle for the tip of the tool and your picture no. 7 confirms it. The smaller stone cannot touch the whole length of the bevel grinded on larger stone. So, in my understanding, everything is OK.

Please let us know what stone you use on your Tormek. Thanks.

Jan

[fritz Mayer]

Hi, it is a CBN Wheel
https://www.dictum.com/de/schaerfen/schaerfmaschinen-und-zubehoer/schaerfmittel-fuer-schaerfmaschinen/704887/optigrind-cbn-schleifscheibe-oe-250-x-40-mm-superfein

It has exact 250mm as Pic10 show.

I made some more fotos, but the problem ist he same ☹

Pic10: The Tormek Wheel has exact 250mm
Pic11: 35mm is also on the top
Pic12: The bench grinder wheel has 200 mm
Pic13: The usb is mounted o Degree
Pic14: The grinder is also mounted 0Degree

The strange is that the error-angle-distance is different.
This mean if I use a tool with SVD-186 (JS=6,P=75,B) I must longer the distance from the usb the the wheel on grinder, when I use a tool (JS=0,P55,B) I must shorten the distance ☹
This mean also that the ,,error-difference" is not constant ☹

Is it ok, that the Tormek-Wheel has 250mm and the grinder has 200mm?
If yes, what could I do to solve this problem?
br fritz

[Ken S]

Welcome to the forum, Fritz.

The two wheels on the TTS-100 are Tormek's patented method of automatically compensating for variations in grinding wheel diameter. The same TTS-100 works with both the T4 and T8, the T4 having a 200mm diameter grinding wheel and the T8 having a 250 diameter grinding wheel. It works equally well with both diameters and no adjustment is required in switching between them.

I use both the T4 and T8 and have reshaped a turning gouge with each. I am writing from hands on experience, not just theory. All of the settings with the TTS-100 and the SVD-186 are the same, regardless of which grinding wheel size is used. In fact, the only difference in settings between the T4 and T8 is the wheel diameter setting with the Anglemaster. When I first acquired my T4, I was surprised to realize that it uses the identical handbook with the T7 and T8.

What is different is the the amount of arc on the ground surface. The 200mm diameter will produce a very slightly more hollow grind. If you use the 200mm wheel for your coarse grinding and use a black marker on the bevel, a 250mm wheel will remove the marker only from the two edges during the power off angle test. This is normal.

Please reply again if this is not your situation. If this is not the answer, we will continue until the problem is solved. Either way, I do not think this will be a long term difficulty. Once solved, you should have smooth sailing.

Ken

ps I have found that CBN grinding wheels work very well with the Tormek. I have a 200mm 180 grit wheel for the T4 and 250mm 80 and 180 grit wheels for the T8. Either grit will reshape a turning gouge in two minutes. While that may not be quite as fast as with a high speed dry grinder, it is plenty fast for me, and the grinding is cooler with the Tormek, wet or dry.

[Jan]

Fritz, in the past I have carefully studied the properties of the TTS 100 jig and have found that it works with very, very small angular error for stones with diameters from 160 to 250 mm. It does not depend whether the stone is mounted on Tormek machine or a bench grinder.

The distance b = 35 mm is recommended for 200 mm stone, but has no influence on the edge angle setting. If your stone warns you will still use the same b distance. So, do not vary about b accuracy. 

Your setting procedure documented in pictures 1 to 7 is correct. To be sure that the edge angle was set correctly simply measure it using the notches of the Angle Master WM-200.

Please keep in mind that the edge angle is defined in the near vicinity of the edge.
Good luck! 

Jan

[cbwx34]

The strange is that the error-angle-distance is different.
This mean if I use a tool with SVD-186 (JS=6,P=75,B) I must longer the distance from the usb the the wheel on grinder, when I use a tool (JS=0,P55,B) I must shorten the distance ☹
This mean also that the ,,error-difference" is not constant ☹

I don't actually sharpen these... so this may be more of a question for those that do, than an answer.   

I noticed in the book "Shaping and Sharpening Woodturning Tools" that comes with the BGM-100, on p. 25 it has a picture with various jig settings and edge angles.  According to that chart. only a couple of settings.... JS2/45° and JS4/55°  you can "use the TTS-100 method".  For other geometries it says to "use the Marker Method or the Spacer Block Method".

Since your settings in the quote seem to fall outside the "TTS-100 method"... I'm wondering if this is the source of the "error" you're seeing? 

[fritz Mayer]

Thanks for you answers. Now I played two days with it. My experiances are:

• BGM-100 is only to form the tool, which mean the figure is no perfect. For a perfect tool you must finished the grinding on a Tormek. Bench Grinder do nly a start job. Sometimes it take longer time and somtimes it is fast on the tormek
• Grinder wheel and Tormek wheel should have the same diameter (250mm), if not you get "hollow" reasen is the diffent radius as Ken said before
• So it is not the easy tool that I hoped

br Fritz

[Ken S]

Fritz,

Übung macht den Meister. I believe you will find your BGM-100 setup as capable as your T8 for reshaping. I prefer the cool running Tormek for final resharpening.

I would not worry about the very slight difference in hollow with different diameter grinding wheels.

Make sure you register your T8 on the tormek.com website. This not only activates your warranty, it lets you watch a very good video on the Tormek website which Tormek reserves for registered owners.

If you do not already have the Tormek turner's information box, I highly recommend it. I do not know if  it is available in any languages besides English. It is very well done. I consider it essential for Tormek turners.

Have patience and keep learning. You will master the Tormek.

Ken

[cbwx34]

• BGM-100 is only to form the tool, which mean the figure is no perfect. For a perfect tool you must finished the grinding on a Tormek. Bench Grinder do nly a start job. Sometimes it take longer time and somtimes it is fast on the tormek

I thought this was the point of the bench grinder setup... to do the major removal... then transfer to the Tormek for final shaping, sharpening, and maintenance? 

[RichColvin]

Fritz,

I added the BGM to my 8" grinder, & use it for reshaping tools that I later resharpen on the Tormek.  As you noted, the difference in diameters (8" vs 250 mm) does leave a slight hollow grind when first coming off the bench grinder.  That's ok for me as the Tormek then adds a micro bevel, & over time the slight hollow from the bench grinder gets ground away.   

I haven seen what you are talking about regarding different angles.  But I did notice you have mounted the BGM quite high off the bench.   I didn't add blocks like that.   Don't know if that makes a difference or not. 

Oh, by the way, I use the BGM all the time on some scraper tools which have carbide inserts.   It's the only way I can get a significant burr easily. 

Rich

[Ken S]

I prefer to do my coarser grinding with my Tormek. I do not own an eight inch dry grinder. I have not converted my six inch grinder with a BGM-100. Therefore, I must admit that I have no direct use experience with the BGM-100.

That stated, I can not imagine why the BGM-100 arrangement would not be able to grind any combination with the SVD-186 that a Tormek can grind.

Also, as long as the BGM held the universal support bar level and parallel with a properly trued grinding wheel, I can not see where placement, within reason, would make any difference in performance. As long as the Distance between the universal support bar and the grinding wheel was consistent with the TTA-100 or Anglemaster, the BGM should be capable of any set up the Tormek can do. Dry grinding wheels will wear with use and decrease in diameter. So will Tormek wheels. The TTS compensates automatically for this wear. The Anglemaster easily corrects for this manually. When Jan states that an angular error is very, very small, that gives me the confidence to disregard that error.

I have compared chisel bevels that I have just ground with the T4 and T7, my mind knows that both are hollow ground and that the eight inch wheel produces more hollow. If I look closely, I can detect the hollow ground. If I look VERY closely, I can detect more hollow grind from the eight inch wheel. I look at a bevel hollow ground with a six inch grinder, the hollow grind is obvious to me. As Rich states, finish grinding with a 250mm wheel over rough grinding with a 200mm wheel soon obliterates any hollow grind difference.

One reason why learning the Tormek may seem difficult is that we learned so many life skills many years ago. I am certain that using a Tormek is no more difficult than driving an automobile. Since I have been driving  for fifty years, any difficulties have long since been forgotten. With a new Tormek, whatever difficulties we encounter are in the present. With study and practice, these difficulties are soon overcome.

Ken