Grinder Belts and Blow Outs.

B

BizzarroBladeWorks

Joined
Sep 19, 2016
Messages
7
Not sure where to post this one.

I bought my first KMG 2"x72" about a month ago, but the Hermes belts don't seem to perform as expected. I ordered a bunch from Tru-Grit and the dang things keep busting at the glue joint.

I called Tru-grit, they are great about sending replacements, but I'm still having trouble with the belts blowing out.

I'm here to tell ya, it is no fun to be concentrating on a grind, the whole world shut out, nothing but you and the blade, head down, focused in...then BANG!! belt blows out.... and I'm out in the shop looking for clean drawers....

Anyone else run into this?

It's happening so often I'm starting to get jumpy around the grinder.
 
I've had that problem with old belts stored open in the unheated shop -

age and humidity seems to contribute
 
I've never had that happen... Is your grinder running too fast for the belt rating? Or you might be pushing too hard on the belt which is another reason I hear can cause this to happen.
 
Are the hermes the purple ones? I've had several brands, including the purple ones, that have spent a couple years in my shop without climate control and have never had one snap yet. I'm also using a KMG and I torque the arm down so its almost parallel to the tool arm.

Just speculating here but it sounds like you might be getting a bad batch. Just for the hell of it order a different brand of belts from someone else and see how they hold up. You can get cheap AO belts from Amazon and see if they snap. Only ~$2 a belt and I personally prefer them for handle shaping over ceramics.

Your post made me laugh by the way :D

-Clint
 
Kinda what I thought at first was a bad batch, but the second order is doing the same thing. My shop is unheated for the most part unless I'm in there, so that may be the issue. It was getting well below zero degrees (F) in there until recently.

I think I'll order some 3M and see if that helps.

The Belts where the brown backed Hermes. The J Belts have not blown out.

I'm running on medium speed wheel, grinding a 220 grit and the 400 when they bust.

Could be the cold...... never thought about that.
 
bad belts happen as can the age of them
2 times in the last 10 years i have had a batc of them pop on me ir i remember right was late winter early spring (i by in batches of 10 ) supergrit didnt bat an eye and repaced them and then checked the inventory
 
I run those same hermes belts from TruGrit. Not have a blow out yet and use them a lot.

Could be a bad batch for sure.
 
oh yea that wakes you up pretty quick ! belt smacks ya a good one,you act like a child and wonder what you did wrong!!!
then you realize the belt broke and smacked you one,you get mad after checking for injury.
sometimes it is because there was too much tension on the belt,or you left the belt under tension on the machine after last use.
it could be bad belts ,might be too much tension ,try to back off the tension 1 notch and see if they break
(stand to the side when turning the machine on)
 
I had 3 belts in a row blow out on me this weekend. If I had not been wearing a ball cap I'd probably have a bad road rash on my face about now. It appears that I got a bad batch of Bora-7 belts, but Supergrit did not hesitate to replace them.
 
I have never taken a belt off any of my machines, nor have I needed to.
And I use both cheap and expensive belts-wet and dry.
 
I've had that happen with a bunch of belts that I found in a local hardware store, they're old 3M resin bonded belts, I got hit with one so hard today that it left a welt on my shoulder. I got them at 80 cents per belt so its not a huge deal, they cut really well until they snap, its like a scary game. Ive been really happy with ceramic Blaze belts for rough grinding , and silicon carbide from Combat abrasives for finishing.
 
I had a discussion with Pop's this past weekend over this issue. He said that Klingspore and others tell him that the shelf life on a belt is one year. I have had belts that stayed on the shelf for 10 years and never broke... and ones that popped for no reason after barely a year. I suspect that the manufacturers use the one year rule to avoid the issue of occasional bad glue joints. Tension, heat and humidity seem to be the major factors in shortening the life.
 
It should never happen!
In many years and a lot of belts, I found that the breaks are more frequent when you realize flat grindings. The friction between the belt and the plan is great and puts a strain on the belts not perfect. Try to use the belts of the bunch that break, to achieve concave grinding. Usually in this grind the tapes are better resistant.

_________________________
Riccardo Mainolfi
 
Do any of you use any kind of guard for protection? I have thought about just a bar across the belt area near the wheel. Anyone tried it?
 
I had three Hermes belts from Tru grit snap at the glue joint. All 60 grit AO. They sent me replacements and they were fine. Only time I ever broke a belt.

Sent from my ASUS_Z01BDC using Tapatalk
 
Talked with Tru Grit today. There is no way they are old belts. They move them almost as fast as they can stock them.

If they are breaking give them a call again.
 
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