Just got a Boyar Schultz 6" x 12" grinder for the home shop. It seems grind pretty square for an $200 old machine, ie. two sides of a bar within 0.0002 over 4", but the surface is a little wavy looking. The spindle is tight, but there is about 5 degrees of backlash between the motor shaft and the spindle shaft. I think it's direct drive with some kind of toothed coupling between the motor shaft and the spindle. The
3/4 hp 3 ph. motor looks original. Maybe this coupling is effecting the finish? I did a google on Boyar Schultz but no response. I guess they are no longer in the grinder business...anyone have a manual for this machine or parts info? Also I plan on grinding valve shims for the Jag DOHC engine, these are ~1/2" diam, 0.080 to 0.100" thick. I'm thinking they can go right on the magnetic chuck, with perhaps some kind of a "backstop" to keep them from flying - any suggestions?
Let me preface this by saying that I do not (yet) have a surface grinder. I do recall reading somewhere that the surface finish from a grinder with a 3ph motor can be affected by poor 3ph power as in from an unbalanced rotary converter. The developed leg gives a "lumpy" torque profile which is reflected in vibrations and surface finish. A good quality VFD should provide clean power.
Lots of factors to consider. - grit and hardness of the grinding wheel. - how you dress the wheel - are you using coolent? - are you using VFD, static phase converter, RPC ?? - feed rate - hardness of material I'm sure harold will have a few more!
Well I am using a rotary phase converter. I've never checked the output voltage/current balance at light load, ie the grinder at 3/4 hp. It's balanced to less than 5 volts difference on each phase when I run my 10hp motor on my lathe. I'll try running the grinder with the lathe motor on to see if there is a difference.
I have 67 E roadster that I have Raced in SCCA for a long time. Started as a autocross car, then GT1 then finally got it reclassified with 45 DCOE webber carbs to GT2. Was reasonably competive in GT2, especially considering the money dumped into the Nissan and Porsche competition. Has Carrillo rods, Weaver dry sump, AP Front brakes, Wilwood outboard brakes on rear, Torsen diff, and coil over Penske shocks on the front, as I couldn't fit stiff enough torsion bars. Lots of homemade parts since pretty much everything needs to be custom made. Last ran at the runoffs several years ago, but parked since due to a house project. I'd like to get back and do some NEDIV regionals sometime if SCCA has not screwed with the classification. Tires, entry fees and fuel are about 5 times more than they used to be....
I really really doubt it's your phase converter. I suggest you balance your wheel, dress it, break the corners with a dressing stone, and balance it again, make sure the ways are lubricated correctly, check the belts, and try your test again. If your wheel adapter isn't set up for balancing you can get one that is from Chevalier's office in Los Angeles. I know because I ordered 2 of 'em.
You're right. Lots of factors, most of which are not real obvious and may not appear to be related. My money says the machine has bad bearings, but it could be something else. I'll toss in some ideas, but without seeing the machine, it's really hard to get a clue.
Most importantly would be matching the abrasive to the material. Aluminum oxide for steel, never silicon carbide, be it green or black. The wrong wheel will yield that result almost instantly due to it's behaving as if it's dull or loaded.
Wheel should be firmly tightened, but not over tightened. Use short handled tools with no cheaters.
It is well known that minor bearing defects in surface grinders will manifest themselves as waviness---and it takes less than .000010" deviation for the surface to appear that way. In essence, if the bearings are marginal, it's not beyond reason for the surface to have a wavy appearance, all the while being quite flat, at least in general shop terms. Nothing but bearing replacement will fix the problem, and then only if the bearings are installed properly, and they're high precision bearings.
A wheel that is too hard will also yield similar results, as will a loaded wheel. Each of those conditions are very similar to one another and are often hard to discern from one another. A close inspection of the wheel will often speak volumes.
It's entirely possible the coupling is affecting the finish, particularly if it does any moving about. Flat surfaces are very sensitive to minor deviations, and it takes very little to create an undesirable pattern. If the machine was belt driven, I'd even suggest flutter in the belt, which often has a profound affect on the finish. Any similar action by a coupler could be a problem.
Grind wet, if possible. Dry grinding is always trouble, and should be avoided if possible. Flood cooling is best, but spray mist is better than nothing.
I suspect the shims are heat treated, maybe around 45/50 Rc. An aluminum oxide wheel, maybe a Norton 38A, 46 to 60 grit, L or M hardness, vitrified bond, diamond dressed (don't break the corners as Grant suggested. That serves NO useful purpose), and *don't* plunge grind. Start on an edge and feed across, maybe .030" per pass, with anywhere from a couple tenths up to maybe .005" depth of cut (how they stay put on the chuck will determine how much each pass will tolerate, plus how much has to come off will also dictate), and allow the balance of the wheel to spark the part. Grind all the way across the part (@ .030"/per pass), until the wheel leaves the far side. If finish is important, dress the wheel and take a finish pass of only a couple tenths, again, about .030" per pass.
As you suggested, block the pieces with a thin steel strip to prevent them from moving under the wheel. Grind this way until the working edge of the wheel starts to break down such that finish starts to suffer, at which time you should dress the wheel slightly more than the depth of cut, to restore the wheel to a flat condition side to side. You should be able to grind one hell of a lot of pieces before the wheel needs to be dressed. If not, there's something wrong with your choice of wheel. Remember, softer wheel for harder material, harder wheel for softer material. Finer wheel for better finish, coarser wheel for faster stock removal, but at the cost of a better finish.
I also have a Boyar Schultz 6 x 12 and replaced the hard rubber / fiber coupling. Just take the part to a bearing supply house and they can identify the replacement. Mine was a Lovejoy L076?. Less than $20 if I remember correctly.
Changing is relatively easy, but you will likely need a copy of the manual. Email if I can help
I have 67 E roadster that I have Raced in SCCA for a long time. Started as a autocross car, then GT1 then finally got it reclassified with 45 DCOE webber carbs to GT2. Was reasonably competive in GT2, especially considering the money dumped into the Nissan and Porsche competition. Has Carrillo rods, Weaver dry sump, AP Front brakes, Wilwood outboard brakes on rear, Torsen diff, and coil over Penske shocks on the front, as I couldn't fit stiff enough torsion bars. Lots of homemade parts since pretty much everything needs to be custom made. Last ran at the runoffs several years ago, but parked since due to a house project. I'd like to get back and do some NEDIV regionals sometime if SCCA has not screwed with the classification. Tires, entry fees and fuel are about 5 times more than they used to be....
Anyone want a pair of these Boyer Shultz..Ive got a pair to give away free to anyone who wants them. Both need spindle bearings, and some paint/tlc.
If not..they are going to sit outside until they rust to pieces.
Gunner, with a Ramco 6x18 and just scored a Covel 6x12 thats pretty nice.
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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