Boyer Schultz 618 Challenger

Jonathans

Jonathans

Joined
Jan 9, 2008
Messages
588
My B&S surface grinder is really lacking power at 1/2hp. It doesn't take much of a bite to bog it down, which is fine for precision work, but not so much when I want to flatten a piece quickly. I am thinking about increasing the HP and was wondering whether any of you guys have already done so.
Jonathan
 
Amazing timing for this question.............................

Just this afternoon I was musing about my, long overdue, pending, conversion of my Boyar Schultz to belts and wondering if converting it to variable speed (with a new motor) was worth considering dpong at the same time and, if so, would that require a special motor?

BTW I'm not unhappy with the motor it has, which, I believe, isn't the original but is still working fine with wheels, but in for a penny in for a pound, ehhhhhhhhhhhh?

Corey "synthesist" Gimbel
 
Jonathan, how much downfeed are you taking at a time, and how much cross-feed per pass?

If you are using a stone wheel rather than a belt conversion, .005" down per cover and .020 crossfeed per pass are what I'd consider pretty aggressive roughing. If I step up to .080" over per stroke while taking .005" downfeed the belt on my 3hp 8x24 will sometimes begin to slip.
 
IIRC I read somewhere, and I think it was Nathan, that said the motors on surface grinders are special because they are precision balanced and should not be replaced. I suppose a factory replacement would probably be OK but I imagine that they are not cheap. I have a stone on mine and like Salem said you can't really remove much metal each pass though everything I've read and heard is you can be a bit more aggressive with a belt at the cost of precision.

-Clint
 
Well Salem, I would say you identified the cause of my problem. While I have only been taking a .005 or so deep bite each pass, I've also been moving the wheel over three turns each pass which is around .25 or more each pass. When I get close to flat I only go .003 deep and around .125 cross feed per pass. So I guess The hp is fine for what the machine is meant to do. Maybe I need to do a belt conversion for more aggressive grinding, but then I might lose the fine finish that I can get from the stone. Thanks for the info.
 
Well, that would seem to be in keeping with my understanding of the way my machine works, at least. When I got it, I'd try to take too much depth at a pass- quit doing that, to find that I still had a warping problem that even the addition of flood coolant didn't really fix. What I found helped that, and helped my machine rip through hogging cuts with full power, was reducing my step-over with each pass.

I've been debating the merits of conversion, as well. For now, I don't think I'll do it- my machine works fine, and since it's auto as long as I'm doing other things while it cuts, much time is saved grinding out billets and the like.

There are guys who know more about these machines here though, I'm still a relative surface grinding novice.
 
I'm surprised you've been able to push it that hard. .005" @ .250" is pretty fast for a grinder that size.

If you need to take a large amount of material off with a surface grinder in order to flatten things out, the fastest way to do it in my experience is to take a larger depth of cut with a smaller infeed. Say, .020" depth of cut but with a .010 or .020" infeed. It does take longer for that particular pass, but usually it's faster than taking 4 passes at .005" DOC. One reason it's faster is that it breaks down the corner of the wheel quickly exposing new cutting surface, where multiple shallow passes has a greater tendency of loading the wheel rather than breaking it down.

Additionally just like belts, coarser wheels are faster at removing material. I've always liked Radiac red wheels for that type of work.

Last, a little trick, when dressing the wheel with your diamond, after you've set your depth and trued the wheel up so you know where everything is, take a .0015" pass at very rapid infeed rates. Maybe 75% as fast as you can turn the infeed. This will leave a coarser surface on the wheel which will also help eliminate loading. It may be tough to get the finish you want with it dressed that way, but usually it is fine.

I have zero experience with belt conversions. And my favorite surface grinders are automatic and programmable, like Salem said, who cares how long it takes if you can be doing something else.

To get surface grinding precision flatness and finish in a faster process, the only option is really blanchard grinding, which is out of the realm of most people given the nature of the machines and it's not quite as precise or as good at finishing.
 
Thanks Kuraki,
I was so happy to have gotten a killer deal on my manual surface grinder and chuck. I must say though, for anyone looking to get one, get an automatic one. The wheel spinning can get quite tedious with a manual machine. I would have much more patience if I could just "Set it and forget it"! Kuraki, what grit Radiac would you use for "quick" stock removal?
 
If I were picking a wheel for planing, just decking flat typical blade steels for quick stock removal I would likely pick 1 wheel for roughing and 1 wheel for finishing. The roughing wheel would be an RA (Friable Ruby) 24 (grit) G or H (grade- hardness of bond agent) 14 (open structure) V8 (vitrified bond) and the finishing wheel would be a WRA (Friable mixture) 46 to 60 (grit) K (grade - harder than rough wheel) 8 (more dense structure) V8 (vitrified).

Basically a coarse grit wheel that is friable and open to rough, and a denser higher grit wheel for finishing. The wheel I specified for roughing will not hold it's form very well so would not be good for any form grinding, the point of using that wheel is for it to break down from the corner to keep fresh abrasive cutting. Just for making things flat.
 
So to be practical I looked around at suppliers and it will be tough to find that wheel I spec'd for roughing in anything but an 18" or 24" diameter.

You may be limited to 46 grit. I would still want a more friable, open wheel for roughing.

This Norton is about as close as I can find readily available on MSC anyway. http://www.mscdirect.com/product/details/05934005
 
kuraki said:
So to be practical I looked around at suppliers and it will be tough to find that wheel I spec'd for roughing in anything but an 18" or 24" diameter.

You may be limited to 46 grit. I would still want a more friable, open wheel for roughing.

This Norton is about as close as I can find readily available on MSC anyway. http://www.mscdirect.com/product/details/05934005
Click to expand...
That's the one, diff hardness but real close.
 
The people that I have seem trying to hog off a bunch of material, say knocking the tops off pressed ladder pattern damascus, have used a big face mill or a large angle grinder. Surface grinners don't seem to be designed for that kind of heavy stock removal. I don't have a surface grinder so I use and angle grinder for the roughing and the platen on my KMG and a magnet for the last bits.
 
Thanks Kuraki and Don for the very helpful info.

jdm61 said:
The people that I have seem trying to hog off a bunch of material, say knocking the tops off pressed ladder pattern damascus, have used a big face mill or a large angle grinder. Surface grinners don't seem to be designed for that kind of heavy stock removal. I don't have a surface grinder so I use and angle grinder for the roughing and the platen on my KMG and a magnet for the last bits.
Click to expand...

That's great JDM! I actually did take down a ladder Damascus billet on the surface grinder. Took all afternoon, and not to be done again. The Angle grinder with a cup she'll has worked out best, but I still yearn for a method that is easier on the back! Perhaps one of those 20" disc grinders with a 36 grit disc on it.
 
Build yourself a grinding station with a grinder holder. Ed Schempp has one, I was looking at it when I was over there. A pretty simple build.
He had a big magnet IIRC that would hold stock down to be ground, using a snagging/cup wheel on a 7 or 9" angle grinder. The grinder hanger was the best part, a track made from square tube, aligned overhead above the magnet, with a top roller from which hung a chain and spring for the grinder to hang from. The chain and hook made it height adjustable, and combined with the spring made it possible to make the grinder "float" close to the work surface, requiring very little effort to move around. The whole works would roll along the track, left or right while grinding billets. Ed had a big dust collection plenum on the wall right where the sparks would go, too.
I wouldn't use my SG for ladder billets, if not for the auto table. As it is, I still have to walk over there a lot to start each new depth cut, but that's OK.
 
You know, if you're doing a lot of that ladder Damascus, that's got a lot of similarities with snagging castings. In the foundry I worked in anything that needed a lot of material hogged off went to what we called a swing grinder.

Think if a compound miter saw from hell was crossed with a 24" grinding wheel on a tool balancer. That one ran on a 1” airline but a smaller version would make really quick work at stock reduction without using your back since it's neutrally buoyant with the counter weight. With some bike handles in front it's quite easy to control.

I'll try to find a photo on the web.
 
I can't get a link on my phone Google swing grinder and they pop right up.
 
Guys, you're putting my brain into overdrive with ideas. A parallelogram, cantilevered, holder for the grinder, counterbalanced to let the grinder float sounds great. My old back its already applauding. If I ever get it built I owe you guys!
 
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