Stihl USG chain grinder angles... Question for those running one

[Mike Kunte]

Hi Guys & Gals!

I have a question regarding the Stihl USG chain grinder. As far as I know, the markings for the side plate angle (referred to in the manual as the A-scale) show the zero degree setting at the top, i.e. the 12 o'clock position, or when the wheel is vertical. This setup is different from the Jolly/Tecomec/Oregon grinders, which have the 90 degree setting at the 12 o'clock position. Am I thus correct in assuming that in order to get a side plate angle of 60 degrees on the USG, that it has to be set at 30 degrees?
On the Oregon, it's as simple as setting the scale to 60 degrees.

The reason for my question is that I have a friend who has the USG, and has recently added a CBN wheel to his grinder collection. He called me to say that his CBN wheel is contacting his depth gauges on the way down, so I suggested to him that he set the A-scale to 30 degrees (90-30=60). He is hesitant to set it at 30 degrees, because the manual stipulates a 40 degree setting. This just does not seem right to me. Could someone clear this up for me please? Surely the 40 degrees in the manual results in a 50 degree side plate angle. This is waaaay too acute... especially considering Stihl calls for a 60 deg angle on the RS chain, and even steeper 75 to 80 deg on the RM and Duro chains...

Regards,

Mike

 

[SimonHS]

Hi Guys & Gals!

I have a question regarding the Stihl USG chain grinder. As far as I know, the markings for the side plate angle (referred to in the manual as the A-scale) show the zero degree setting at the top, i.e. the 12 o'clock position, or when the wheel is vertical. This setup is different from the Jolly/Tecomec/Oregon grinders, which have the 90 degree setting at the 12 o'clock position. Am I thus correct in assuming that in order to get a side plate angle of 60 degrees on the USG, that it has to be set at 30 degrees?
On the Oregon, it's as simple as setting the scale to 60 degrees.

The reason for my question is that I have a friend who has the USG, and has recently added a CBN wheel to his grinder collection. He called me to say that his CBN wheel is contacting his depth gauges on the way down, so I suggested to him that he set the A-scale to 30 degrees (90-30=60). He is hesitant to set it at 30 degrees, because the manual stipulates a 40 degree setting. This just does not seem right to me. Could someone clear this up for me please? Surely the 40 degrees in the manual results in a 50 degree side plate angle. This is waaaay to acute... especially considering Stihl calls for a 60 deg angle on the RS chain, and even steeper 75 to 80 deg on the RM and Duro chains...

Regards,

Mike

Yes, it is the complimentary angle I believe. Here is a link to the manual:

https://www.google.com/url?q=https:...4QFnoECAcQAg&usg=AOvVaw0SmKv3-0WgtVA0JMrB_Ane
It's also worth noting that Stihl recommends that the grinding wheel be dressed asymmetrically, with more radius on one side. The picture below shows it. I think that this helps grind a better hook shape.

 

[RedneckChainsawRepair]

I do A 40 - B 10 - C 30 https://www.google.com/url?sa=t&rct...es_chart.pdf&usg=AOvVaw2kGWI1YCVr1kvQ8um5cyoO

 

[Mike Kunte]

Thanks, Simon!
The manual contributes to the problem, since it never states another angle for the A-scale than 40° (see p.20). However, on p.16 it specifies the different angles for different chain types. How can one achieve different angles without adjusting the A-scale? It's just not possible. The A-scale has to be adjusted to suit the chain.
I hope we can clear this up.

Mike

 

[SimonHS]

Thanks, Simon!
The manual contributes to the problem, since it never states another angle for the A-scale than 40° (see p.20). However, on p.16 it specifies the different angles for different chain types. How can one achieve different angles without adjusting the A-scale? It's just not possible. The A-scale has to be adjusted to suit the chain.
I hope we can clear this up.

Mike

I have a USG in pieces in my shed. I haven't had time to get it working, so I haven't hit this problem yet.

If you set the angle by eye, so that the wheel clears the depth gauges, how many degrees do get?

 

[Mike Kunte]

Simon,

The grinder belongs to a friend who is 300 miles away! I'm doing telephonic support. If I had the grinder with me I'd measure the angles directly.

Mike

 

[Mike Kunte]

Anyone willing to put a protractor or digital angle gauge on the wheel to confirm the angles for me?

 

[RedneckChainsawRepair]

I just use this for a guide.

Not rocket science or that picky to grind.

 

[Dennisthemenace]

Yes, it must be the complimentary angle. I too have been confused by this but I've learnt to sharpen Stihl chain with the super jolly at what angles suits me. RS 57 30 0. RM 60 30 0. 404 in fairly clean, fairly green Oz hardwood

 

[Mike Kunte]

Thanks, DTM!

I think your angles on the Jolly are pretty spot on. Interesting that you went below 60 degrees on the RS chain. In the harder Ozzie woods, I would think that an angle closer to 70 degrees would give you better life on the cutters.

Thanks for your reply!

Mike

 

[bullittman281]

I run one all the time at work. I follow the Stihl guide on the 3 angles. We run 3/8 .050 RS and 3/8 pico .050. Use the wheel guide to set the radius on the edge of the grinding wheel. I find stetting the depth of the wheel the most confusing and touchy part. I've found that the "corner" of the grinding wheel should pass through about the middle front to back of the top plate of the chain cutter. This "corner" is where the radius ground on the end of the wheel ends and becomes the side of the grinding wheel. It sounds confusing but is easy enough to see when the wheel is spinning. I find these wheels load up really bad with metal and need dressed all the time. The heavies deposits show up in a band just below this "corner" of the grinding wheel I speak of. I typically have to dress the wheel after each chain. I've found the included wheel dressing stones lacking as well. I ended up with a diamond coated block for dressing bench grinders and its far and away better. Its agressive and takes a very light touch but the wheel cuts far better and stays clean longer. Its obvious when the wheel is dirty. The sound, feel, cutting speed, and propensity to burn cutters change when the wheel loads up. I've experimented with different angles and tried to replicate the grind of a new chain but in the end I've ended up back with the instructions recommendation. Everybody at work likes the way the chain cuts, especially compared to the way others use the chain grinder. The two big errors I found at work were cutting the cutters WAY too deep and burning them with impatients. The too deep comes from setting the grinder to grind just a little deeper than before to make sure its down in there. Half way through the chain its into the tie straps. There is no need to touch the tie straps. If its getting into them the radius on your wheel is wrong. I use calipers to measure the cutters and make sure that both sides are the same. With a light touch and effort to do every thing the same these work pretty good and turn out consistant cutter length. It takes a light touch. In the end I like Oregon style grinders better but they only grind saw chain, not everything else like these things can.


Bullittman

 

[John Lyngdal]

I have my USG set at the factory suggested angles and those seem to work fine. If you're having clearance issues, position the stop behind the raker rather the cutter to gain some extra clearance. I bought a Diamond Corp. CBN wheel for my USG and even after using the supplied dressing stone it doesn't cut worth crap. It like the compound it too fine of grit sot to say, it leaves a mirror finish on the cutters but removal of material is painfully slow and burning cutters is far too easy. I just switched back to a rock wheel and keep it dressed properly. What brand CBN wheel did your friend purchase?

 

[Mike Kunte]

We're both running Baltic Abrasives CBN wheels. They cut cleanly, quickly, and they keep their cool!
Mike

 

[bwalker]

You set the grinder up to net the tooth profile you want. You can't just set to the angles on the grinder and expect great results, especially with the Tecomec clone of a Oregon 510 and its clones. With my 510 clone the angles even varied from side to side. They just aren't that precise. Maybe the USG is or something like a Silvey is different?

 

[John Lyngdal]

We're both running Baltic Abrasives CBN wheels. They cut cleanly, quickly, and they keep their cool!
Mike

Is there a US distributor for them, or do I need to have them shipped from Lithuania?

 

[Del_]

USG Square grinding accessory. I'm just tossing this into the mix in case anyone else has or has seen one. Bought it directly new from Stihl in VA back in 1990 or so.

 

[Mike Kunte]

Not sure. We're based in South Africa. We shipped on from Lithuania. Goods arrived in about 2 weeks. Very good service from Inga.

Mike

 

[John Lyngdal]

Not sure. We're based in South Africa. We shipped on from Lithuania. Goods arrived in about 2 weeks. Very good service from Inga.

Mike

Thank you for the correction.

 

[John Lyngdal]

USG Square grinding accessory. I'm just tossing this into the mix in case anyone else has or has seen one. Bought it directly new from Stihl in VA back in 1990 or so.

View attachment 967951

Major league envy.
I'd love to stumble on to one of those upgrade parts set.

John

 

[Dennisthemenace]

Thanks, DTM!

I think your angles on the Jolly are pretty spot on. Interesting that you went below 60 degrees on the RS chain. In the harder Ozzie woods, I would think that an angle closer to 70 degrees would give you better life on the cutters.

Thanks for your reply!

Mike

Clean and green timber, if it wasn't I'd be using the RM