Belt splice problems

S

Storm W

Joined
Feb 19, 2019
Messages
915
I have been having a problem with belts breaking. The first is cork belts. They just tend to let go. I assume that they just can't handle much grinding pressure. If there is anything that I can do to keep them together I would love to know it.

The second is a extra heavy scotchbrite. I love the thing. It takes out 120 scratches super fast and runs cool. The belt is very stiff and the splice is stiffer. It's slowly coming loose. Is this a defective belt or am I using it wrong? Is there a way to repair it? Its barely broke in and its expensive.
 
I was hoping someone with similar problem would take the time to speak up, but it doesn't seem anyone else is having these problems.
I will offer some suggestions and hopefully facts which may help.

Check with the belt manufacturers and see what their recommended speeds and tensions are. If they have literature on your specific belts offering suggested use and procedures read it.

Belts have a shelf life, In specific the tape joint is the first to go. My experience is they are all good for three years from date of mf. some may make it to 5 years. Beyond this you are grinding on borrowed time. if you hear a fapp, fapp noise start when grinding step away from the grinder; this is usually a sign of a tape joint starting to let go. I assume cork belts and woven belts will follow these trends.
Jim A
 
I have some cork belts I have used for several years.

What brand of cork belt are you using?
 
Age is the enemy of belt splices.

I had a batch of expensive ceramic belts that I overlooked for several years on the shelf. When I found them and put them on the grinder, every one broke within seconds of turning the grinder on. I have had this happen with 6X48 bets that were too old as well.
 
I've only had a few belts break, but was able to identify the culprit. I had my platen, which is made from hardened D2, set slightly too far in front of the upper 2'' wheel. It also had a pretty sharp edge, which I assume was peeling the splice off. Once I radiused the top edge of the platen and set it more appropriately in front of the wheels (by about 1/16''), it eliminated the issue. A secondary issue was speed - cranked to max with a 7'' drive wheel adds a ton of stress on the splice. Once the platen was adjusted, it runs flat-out just fine now.
 
i have had my cork belts for years. can you be sure you are not going too tight on the tension ? is your grinder a spring tension, or ratchet like a tw-90 ? the belt only needs to be tight enough to vibrate or make a sound/tone when you pluck the edge like a guitar string.
 
I do agree that the age thing isn't universal. I have some pretty old 3M belts that work fine. The ones that broke were all Klingspor belts. I have to box them up while moving things to the new shop and send them back for replacement or re-splicing.
 
john april said:
he belt only needs to be tight enough to vibrate or make a sound/tone when you pluck the edge like a guitar string.
Click to expand...
Do you run your cork belts that tight? What about the scotchbright belts? I'll run abrasive belts pretty tight, but the cork less so, and the scotchbright I've not ran tight at all, and don't leave cork or scotchbright belts on after use so they're not under tension while just sitting overnight.
 
Ken H> said:
Do you run your cork belts that tight? What about the scotchbright belts? I'll run abrasive belts pretty tight, but the cork less so, and the scotchbright I've not ran tight at all, and don't leave cork or scotchbright belts on after use so they're not under tension while just sitting overnight.
Click to expand...
Answering for myself, I’ve only had issues with belts breaking on over 5-7 year old grinding belts. Not on cork or Scotchbrite belts and I never leave any belt under tension when I’m done for the day because it can warp, Put a flat spot on your contact wheel(s).. leaving them that way overnight, for a weekend while you’re at a show etc ...The late Bob Loveless taught me that!
 
Laurence, You echo my own thoughts on leaving tight belts. Nothing to gain and a good bit to lose.
 
yes i run the cork belts so they sound a note. its really not much more tension than it takes just to keep the belt on there. i have scotchbrite belts, but hardly use them. i dont think they will sound a note like a guitar string, but i am not sure. i always loosen them before walking away from the grinder. i think the spring tension type are actually harder on belts than the ratchet tensioner. you need a lot of tension pushing back via the spring so the belt wont wander across as you apply pressure.
 
Stacy E. Apelt - Bladesmith said:
I do agree that the age thing isn't universal. I have some pretty old 3M belts that work fine. The ones that broke were all Klingspor belts. I have to box them up while moving things to the new shop and send them back for replacement or re-splicing.
Click to expand...

Re-splicing how do you do this ? I have a ton of belts that i bought and everyone of them comes apart as soon as you turn the grinder on.
 
I have a esteem with a spring tensioner. The cork belt that broke now that I think of it came from pops. He said that he had had them sitting around for a long time and took them off of the site since they didn't sell well. Its probably just really old. This extra course scotchbrite has a thick glued seam that is slowly coming apart. It might just be a defective seam. It's not like the other scotchbrite belts that I have. I find scotchbrite belts have to be run a bit tighter to keep them running straight. I might have to call up trugrit about the scotchbrite belt. That extra course belt is awesome for getting out 120 scratches on some 15n20 chef knives I'm making. I'm grinding lengthwise with no plunges to get washed out. I did have problems with some 3M film belts but I think that it was just the cold season I was grinding in. Above 32 I haven't had any problems. If my new cork belts hold up then age is probably the problem.
 
I have successfully used CA glue to repair Scotchbrite belt joints. On my belts, the edges of the taped joint start to separate. I lightly stretch the belt across a horizontal flat surface covered with wax paper, apply thin CA across the joint, then clamp a flat plate with wax paper across the top of the joint.
Because the scotchbrite is "fuzzy" the CA glue runs down to the tape level. My scotchbrite belts seem to hold up well after this.

I have also tried to glue sanding belt joints with CA glue. It doesn't last long, doesn't work. My broken belts turn into shop roll material for hand sanding.
 
The rep from Klingspor told me the glue they use has a very short shelf life and is kept packed on dry ice until used. He said you can't splice a belt yourself.
 
I should post a pic. Maybe later today. This belt has a typical taped splice in the back as well as a large glue joint on the belt. The glue joint broke slowly and the splice in the back is still holding. I used it a bit more and now the glue joint is broke all the way. It works so good but it was kinda scary since the splice wanted to grab if I got anything horizontal to it. It's not a normal scotchbrite seam or it might have been defective. If I can get it to work I really want to run the belt. It runs cool and blends nicely and if going for a scotchbrite finish it's a quick transition from ceramic belts.
 
Stacy E. Apelt - Bladesmith said:
The rep from Klingspor told me the glue they use has a very short shelf life and is kept packed on dry ice until used. He said you can't splice a belt yourself.
Click to expand...
Another reason for me to not buy Klingspor belts. To me, they would cut well for about 30-45 seconds. For the money, I’m most happy with VSM belts and don’t remember one ever coming apart at the seam..
 
The short shelf like was for them to use it to splice belts. He didn't say how long a belt should last before the splice fails. I have been told it is a few years.
 
You must log in or register to reply here.
Back
Top