Surface grinder belt conversion - super easy

Finally found this thread... I've decided after saying I wouldn't for a very long time, to put belts on the little Doall here. I'll do a build thread for that and one of my other upcoming projects when they happen. I'm thinking of an aluminum wheel and a slight workaround design to allow the wheel guard (at least the back cast part) to stay on while using belts, so there is no temptation to run without a guard when switching back to a stone.

That's the one problem I see with this setup... I've seen stones blow up, and its not the most fun thing to be around
 
I have also seen wheels come apart but it was allways from running them into something. He big thing is if your wheel is even .001 of true the belts will create a scalloped finish. That’s the great thing about using a stone wheel. You can dress the wheel to run perfectly.
 
Don’t know how you would dress an Aluminum wheel on a surface grinder while it’s in the spindle.i mean it’s possible but it would require a lathe turning tool bolted to the end of the mag chuck. You would basically be turning the wheel like you would be on a lathe.
 
I'd be inclined to go for sandpaper on the mag chuck, it works for rubber wheels. File would probably work well enough too
 
Sandpaper would work perfectly .Surface grinders are very precise machine .Grind first with stone from both side small , say 3 x 3 inch steel , glue sandpaper on one side and work with aluminium wheel like it is stone . I mean like you grind blade with stone......done !
 
It was fun being part of coming up with this modification, talking to JT... he thinks a bit different/crazier than a lot of us, when he made the leap to "well maybe I can just run a belt over the stone..." I was like ...."wow that's a crazy thought but I'll bet it would actually work!"
It is a big deal in my book, not only because it makes conversion a lot easier and less expensive, but because it makes running stones or belts on the same rig that much easier.
If course there is always a danger of a crash with an SG, but I think if anything that a stone coming apart is more likely if you crash it without a belt running on its surface. Make no mistake, it's a dangerous machine and needs to be operated with focus and care, but beyond that I don't see why this method is any more dangerous than running a plain stone.
I have a very hard contact wheel on my machine (same Abrasive 3B that JT runs) and I can pull .025" DOC at .120" stepover on medium hard billets, with a fairly sharp 36 grit belt. In practice though I routinely grind all rough stuff at .010" DOC and .120" stepover. I can see taking .025" DOC with the right stone wheel, if the stepover is only .005. You have to think about it in terms of the overall amount of steel being removed per stroke. But that still means that the stone grinder is taking off as much material in 24 table strokes as mine can in ONE stroke.
But again, if you run a belt over a stone like JT, you can have the best of both worlds with no hassle at all switching between the two.
 
Shit I run .025 DOC at full engagement on mine (2"), with a contact wheel, until the machine starts bogging down, with the auto traverse, and walk away, come back 10 mins later, and crank it down again.

To me, this is the only real reason to run a belt, and while I'm about as far from a "Safety Sally" as it gets, there's no way in hell I'd try that with a stone under the belt.


JT, you understand the risks, so by all means, do what you feel comfortable with, no judgement here, but I hope you guys are clear to any novices, stone explosions aren't just "scary" they're legit deadly, and even if they don't kill you, they're maim-ey as hell.

The thing that typically mitigates this danger with a stone, is the wheel guard (which far too many knifemakers don't have on their SGs). It's one thing for someone with experience using these machines to "measure the risk" and take it, knowing how to avoid a crash, but I'd really really hate to see someone try this "mod" that hasn't had hundreds of hours on one of these machines like we all have.


Personally, I don't see the advantage here, for me, the only reason belts work is because of the compress-ability of the contact wheel, allowing for extreme, hands-free hogging, but maybe I'm missing something. Anyway, I hope anybody else that considers this, understands, this is potentially, extremely dangerous. Salem, I can see how it "makes sense" in the mind that it would be safer to have a stone explode with a belt wrapped around it, but I don't think you're considering that it's likely channel the fragments forward in a cone, as opposed to most of it flying centrifugally as it would un-wrapped by a belt. It seems likely more dangerous to my mind.

Be safe guys.
 
That is precisely my worry. The wheel guard on my G&L (not the grinder I have set up and running, but its the one in the class of the 3b apart from being manual) is heavy cast iron. It probably weighs 50#. And the front is covered. A belt may as well not be there in regards to stopping a blown up stone compared to a proper wheel guard. And as mentioned if it does anything, it will likely make the stone bits come towards the operator much as using a wheel guard with the front off would.
Now granted the only wheel I've seen blow up was 12" diameter and 2" wide (big pedestal grinder with a defective new stone) but a vitrified wheel going off is not something you want to be around. Grenade comparison wouldn't be that unreasonable if you were in the path of the shrapnel.

Solid aluminum wheel would be cheap and easy, as would getting sunray to make a wheel in their non soft compound (the number for it escapes me, but its as hard as a plastic hardhat). Either of those would be a hell of a lot cheaper than the hospital bill resulting from having that stone blow up.

He's not on here anymore that I'm aware of, but Deker recently had his big Landis grinder somehow grab a power hammer die, take a decent chunk out of both the contact wheel and the mag chuck, and fired the block of steel right across the shop with enough force to dent the wood beam it hit. And that was halfway through the job without repositioning the part or changing the setup, and there was nothing that obviously caused it to crash. If a freak accident like that happens with this setup, you better hope those stone pieces miss you. All it takes is one part coming loose, too heavy of a cut, forgetting to turn on the chuck, ect.
For me the risk vs reward of making an aluminum wheel just isn't there.
 
Geoff Flato said:
That is precisely my worry. The wheel guard on my G&L (not the grinder I have set up and running, but its the one in the class of the 3b apart from being manual) is heavy cast iron. It probably weighs 50#. And the front is covered. A belt may as well not be there in regards to stopping a blown up stone compared to a proper wheel guard. And as mentioned if it does anything, it will likely make the stone bits come towards the operator much as using a wheel guard with the front off would.
Now granted the only wheel I've seen blow up was 12" diameter and 2" wide (big pedestal grinder with a defective new stone) but a vitrified wheel going off is not something you want to be around. Grenade comparison wouldn't be that unreasonable if you were in the path of the shrapnel.

Solid aluminum wheel would be cheap and easy, as would getting sunray to make a wheel in their non soft compound (the number for it escapes me, but its as hard as a plastic hardhat). Either of those would be a hell of a lot cheaper than the hospital bill resulting from having that stone blow up.

He's not on here anymore that I'm aware of, but Deker recently had his big Landis grinder somehow grab a power hammer die, take a decent chunk out of both the contact wheel and the mag chuck, and fired the block of steel right across the shop with enough force to dent the wood beam it hit. And that was halfway through the job without repositioning the part or changing the setup, and there was nothing that obviously caused it to crash. If a freak accident like that happens with this setup, you better hope those stone pieces miss you. All it takes is one part coming loose, too heavy of a cut, forgetting to turn on the chuck, ect.
For me the risk vs reward of making an aluminum wheel just isn't there.
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Yeah, I've shot parts as "bullets" through the sheet metal guards at the end of my table, on my Landis hydraulic SG. It's not a huge one either, it's a 618 Hydro with a 2 or 3 hp spindle.


FWIW, it's not that hard to modify most SG's so you can easily swap between stones and contact wheel (yes, this is a $250 or so investment if you get it from Sunray, but there are other options, lots of cheaper "off the shelf" contact wheels can be bored out for your spindle hub, in about 5 minutes on a lathe), I did this on my larger one by cutting two slots in the top of the wheel guard, and mounted my tensioning arm for the belts on the back of it also. In the case of this grinder, it's 1/2" thick cast iron.

All I have to do to swap from stones to belts, is open the guard door, pull the stone off, put the contact wheel on, tighten the hub flange, slap a belt on. Takes 30 seconds or so, and I've got a guard in each circumstance. Yeah, I probably reduced the efficacy of the guard a bit for stones, by cutting those two slots in the top for the belt to pass through, but, if a stone does blow up, I'm not concerned so much with a couple of pieces flying straight up through those holes, and the guard is still super stout.


I'll admit I do run my two smaller grinders without wheel guards, because whoever had them previously removed them, and lost them, but I'm *very* cautious with setup on those grinders (and they're little baby 6x12's), and it's never a "hogging" situation. I'll still put guards on them if I can ever find any replacements, although I'm probably too lazy to actually make guards. Still, I can't count the number of hours I've got in front of a SG, I consider the risk acceptable, but I'm certain still aware that it is a risk. I wouldn't run the bigger ones without them though, not with stones, not for any money.
 
javand said:
...the only reason belts work is because of the compress-ability of the contact wheel, allowing for extreme, hands-free hogging, but maybe I'm missing something...
The thing that typically mitigates this danger with a stone, is the wheel guard...
...the only reason belts work is because of the compress-ability of the contact wheel, allowing for extreme, hands-free hogging, but maybe I'm missing something. Salem, I can see how it "makes sense" in the mind that it would be safer to have a stone explode with a belt wrapped around it, but I don't think you're considering that it's likely channel the fragments forward in a cone, as opposed to most of it flying centrifugally as it would un-wrapped by a belt. It seems likely more dangerous to my mind.
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First, the contact wheel works great if marginally compressable, or not really at all... i.e., an aluminum contact wheel with no tire. (mine runs very hard rubber 'cause that's what I had.)

A wheel guard could be fairly easily modified to work with a belt over the stone if a person wanted. Cheaper and faster and easier than ordering a custom contact wheel.
And the reason I see a belt helping a stone be safer, is that the belt itself offers some cushion to the stone, especially a 36 grit ceramic belt such as we'd be hogging with. The belt would pop if a relatively small mistake was made... if a large mistake is made, well... we learn not to make those at the surface grinder.
 
javand said:
Yeah, I've shot parts as "bullets" through the sheet metal guards at the end of my table, on my Landis hydraulic SG. It's not a huge one either, it's a 618 Hydro with a 2 or 3 hp spindle.


FWIW, it's not that hard to modify most SG's so you can easily swap between stones and contact wheel (yes, this is a $250 or so investment if you get it from Sunray, but there are other options, lots of cheaper "off the shelf" contact wheels can be bored out for your spindle hub, in about 5 minutes on a lathe), I did this on my larger one by cutting two slots in the top of the wheel guard, and mounted my tensioning arm for the belts on the back of it also. In the case of this grinder, it's 1/2" thick cast iron.

All I have to do to swap from stones to belts, is open the guard door, pull the stone off, put the contact wheel on, tighten the hub flange, slap a belt on. Takes 30 seconds or so, and I've got a guard in each circumstance. Yeah, I probably reduced the efficacy of the guard a bit for stones, by cutting those two slots in the top for the belt to pass through, but, if a stone does blow up, I'm not concerned so much with a couple of pieces flying straight up through those holes, and the guard is still super stout.


I'll admit I do run my two smaller grinders without wheel guards, because whoever had them previously removed them, and lost them, but I'm *very* cautious with setup on those grinders (and they're little baby 6x12's), and it's never a "hogging" situation. I'll still put guards on them if I can ever find any replacements, although I'm probably too lazy to actually make guards. Still, I can't count the number of hours I've got in front of a SG, I consider the risk acceptable, but I'm certain still aware that it is a risk. I wouldn't run the bigger ones without them though, not with stones, not for any money.
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Rob's Landis is a 12x18, with either 5 or 7.5hp spindle. When things go wrong on that grinder, they go really wrong really fast.
I am planning on doing exactly that what you described when I eventually set my 6x20 G&L up. That, and getting a second hub so I can swap between the 10" stone and the contact wheel without constant rebalancing. The baby doall I'll be converting for now though doesn't have enough guard to cut anything into, so I'm going to make a contact wheel with 1/2" of backspace on it to push the belt in front of the edge of the fixed portion of the guard. Pop the cover off for belts, stick it back on when a stone goes on. It'll only run 1" wide belts, and it only has a 1hp spindle, so I'm not too worried about moving the wheel out half an inch with the fairly light cuts it will take in comparison to what something like my G&L with 3-5hp will do.



I still really don't like the running belts over a stone idea mind you. As a proof of concept, sure. But a solid aluminum wheel would be a hell of a lot safer for not much time or money. I'd almost be inclined to put this in the category with the hot oil tempering inside a shop as recently started a fire on TV.
 
Salem Straub said:
(shrug)
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No competition here bruv, not trying to criticize you guys for trying something new, it's interesting, and big ups for having the balls to give it a shot. I think 99% of the "be safe" posts here are excessive, egregious BS. However, the danger of surface grinders here, is HIGHLY underrated IMO, especially considering the god-like reverence given to buffers, so I just wanted to offer some critical feedback.

I don't personally see the advantage of running a belt over a stone, but I've been very vocal also, that I see *VERY LITTLE* advantage, to using belts *at all*, for most knifemakers, as opposed to just using a stone. If you're not ripping, 2" Y x 0.025" or more with a contact wheel and walking away, to me, it's a waste of time. You absolutely can get better than any belt finish with a stone if you know what you're doing, and you cannot, under any circumstances, hog as well, with a stone, or hard backed belt, as you can with a contact wheel and belt.

If someone can show me proof otherwise, I'll happily concede. However, in fairness, I have a pretty binary view of these machine's objectives; 1) flatness, parallelism, and finish = stone. (period). (2) rapid metal removal, ignoring the factors of 1; contact wheel + belt. I don't frankly, believe that "the best of both worlds" exists, without heavy compromise.
 
Hey fellas, I know there's a bit of debate to the usefulness, accuracy, and safety of this idea. Especially with high horsepower machines. Found this very interesting.
 
No one wants to be the safety nag guy but I'll throw this in. I had a rep from Norton's abrasive cancel a scheduled meeting once. He had to go to Iowa to follow up on a surface grinder stone that blew apart and killed the operator. You can have a custom wheel made at Sunray in 100 duro-A hardness that takes the exploding wheel of death off the table for less than the cost of a hospital visit.
 
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