Belts for platen grinding?

[Remyrw]

Lately there's been a lot of discussion here and elsewhere regarding belts. Belt value, performance, problems, situations... One thing I can't recall being discussed is which ones are best suited for platen grinding versus contact wheel versus slack grinding. I know it's less of an issue for 2x72 grinders, particularly if you slow things down, but belt "hop" is a hassle with smaller grinders running at high FPM. One of the reasons I use Gator belts a lot on my 2x42 is the lack of any noticeable hop from the joint. Some belts are particularly bad, others are just so so... Some belt lines are specifically mentioned in their documentation as well suited for platen or contact wheel use, others don't say anything at all other than what materials they're for.

I'm just waiting on my 2x72 right now, and ordered a sample of belts to try but figured it's worth asking here as well.

What belts exhibit this hop, which ones don't, which ones do it even on a rubber contact wheel?
I'll start with my experiences in 2x42's since I think these grinders really make things worse with the short belt and high speed.

SY965 Ceramics - Some hop, but not horrid, just don't expect to hold a perfect line
LS309J AO - Same, useable but don't expect perfect holds, a bit more distinct a bounce than the SY965 due to the thinner belt.
CS411X 36 grit - Not a lot of hop noticed, possibly because of the coarse belt as much as anything else. I've never used these in finer grits. This is my 2x42 hogging/profiling belt of choice.
3M Gator Structured Abrasive belts - Best I've found for smoothness. Ironically, I'm not sure 3m's actually making them, I think someone else is making these shorter ones from bulk spools or larger belts. I get mine from Trugrit. 2x42 is not a size 3m lists for this product in their own catalogs.

For slack grinding obviously the 309J's are very soft and flexible, the gators are as well, but tend to bite more at the edge. The SY95 and CS411X are rather stiff and not particularly well suited for it if you want contouring. I haven't used these on a real contact wheel so I can't comment there.

I'm pretty sure I tried some other belts early on and stopped using them because of the belt hop. The ones above are the only ones I have used regularly on my 2x42 in over a year.


Needless to say, I'm excited about the wider options with the 2x72.

 

[ERIK KNIVES]

You seemed to have answered your own question. Hop is worst on a plate, hard to notice on a rubber wheel and even harder to notice on slack. Use the belts that work for you. A 2X72 will make it easier.

 

[rwn2000]

I've tried several different belts since I got my Bader BIII a year ago and generally speaking, the cheaper belts have a lot more hop than the expensive belts. The Blaze and Gator belts are very smooth on my flat platen. The J-flex and Klingspor belts have a lot more hop but I only use them at the finer grits so it isn't that bad.

randy

 

[Remyrw]

Well, it's not "which situation makes it worse" but which belts do better than others. Like Randy said, generally the more expensive belts seem to do better, but it's not a sure thing. I'm glad to hear the Blaze are smooth, now if they'll fix that gunk buildup issue I will give them a try. Anyone using the Cubitron and Cubitron II's? 967F and 984 I think they are. How about 707JE Regalite's? The Norax belts? 977F Regalloy ceramics? 963G Regals? There's dozens out there, I know I would rather learn from someone's experience than try them all one at a time, at different grits....

Mind you, I have some of them already, and once my grinder arrives and I test, I'll post as to which ones I felt worked well, not so well and worst. I just think this issue is worth some discussion along with the other aspects of belt performance.

 

[javand]

I love the cubitron ii's and the 707JEs. Generally speaking, I feel that, the 3m belts show the best quality control. I also prefer the cubitron ii's that I've used thus far to the blaze belts, although I haven't used any in 36g. The 60s, which since I forge heavily, I use way more than 36sers, seems to stay sharp longer, or rather, once broken in, seems to be "much sharper when dull", if that makes any sense.

I've had occasional blaze belts with huge gaps at the splice, which cause some pretty bad skip, and I've also had some that really wobble regardless of grinder alignment. Its pretty rare admittedly, but I can almost always count on any 3m belt to run true.

I also have noticed a lot of platen skip with the j-flex belts, but that doesn't matter much anymore since I'm using them exclusively for wood now, as the 707JEs are much better imho for plunges, and general higher grit work on steel.

Anyway, this is obviously a very subjective topic, so ymmv, etc. I wasn't thrilled with the regular cubitron belts, I think they needed machine pressures to break down and expose fresh abrasive, but I'm thrilled with the cubitron ii's myself, and just generally have better luck with 3m products.

 

[Remyrw]

Glad to hear I was on the right track with the 707JE's. I bought a couple of them to try out for metal work and the regular J's for handles. I figured at worst I'd have the same stuff as I used on the 2x42 so they were worth a try. I got two different cubitrons to try out but you seem to have the same experience other folks were reporting, they aren't nearly as good for us as the cubitron II's, so I'll be ordering some of those next.

Back on topic, I hadn't thought about it like that before, but you're dead on with the brand trend. I just went through my belts and the 3M's are my favorites when it comes to smooth use on platens, followed by Norton's generally. I use, or at least did use, a lot of the SY965 ceramics in 60 and 120. The hop was distinct but not as bad as the 309J's and they last pretty well. Until recently I couldn't find Blaze or other "fancy" options other than the Gators in 2x42 so the 965's were my main workhorses after hogging out with the 36 grit zircs. I always wished they ran as smoothly as the Gators but never really thought about the brand thing.