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Making a Light Ball-BearingColumn Grinder

By RAY F. KUNS

need of a grinder for lightwork, such as sharpening drill bits,

bearing scrapers, punches and chisels,and roughing down l ight f i t t ings for en-gine stands, etc., the scrap pile was lookedover for parts that might lend themselvesto the bu i l di ng of such a machine. Acolumn was located and this was broughtup to pro per heig ht by fit t inga brake dr umu n de r it. It was desired to have themotor mounted with the head so that themachine might be set as a unit and movedon occasion without a great deal oftrouble in re-alining parts.

A piece of 5/16-in. bo iler plate was ob-tained and from it a base for the brakedr um and col um n was cut. An othe r pieceof the plate was shaped for the top plateon which the grinder head and the motormi gh t be mo unte d. As a supp ort be-tween base and top, several lengths ofgas pipe were formed, and riveted andbolted in place as indicated in the draw-ing. A crossba r was we lde d into this

SIDE VIEW

brace to eliminateany tendency to vi-brate. The drawin gsindicate the approxi-mate dimensions of

t h e v a r i o u s p a r t s .Before l aying o u tthe plate with theslots for the motorsupport and adjust-ment, however, i t will be necessary tohave the motor at hand.

The motor used in this case is a single-phase, 1/2-hp. ma chin e. The pulley is 3in., and drives the head pulley, which is 2

158

in. in diameter, at about 3,000 r.p.m., sincethe m oto r speed is 1,800 r.p.m. A 2-in.light single leather belt with a glued spliceis used to drive the grin der head. Thisgives a drive free from any disturbingvibration.

The construction of the head is rathersimple. The first con sider ation is thebea rings . Those used in th is case weresalvaged from a worn-out motor genera-tor. Af ter the bea ring s are at ha nd somedimensions may have to be varied to ac-commo date them. Dimension s of sh af tdiameters are given here in order to indi-

cate the approximate size desirable.The blocks B, which are 1 in. thick and

3 in. wide, are chucked in the lathe andbored out to accommodate the bearingsselected. Su ffic ien t stock sho uld be pro-vided at the bottom of the blocks so theycan be bolted to the plate A as indicated.After the support ing yoke, formed by theparts A and B, has been bolted togetherand the bearings installed, the exact di-mensions of the shaft may be determined.

Wh ere the s haft passes th ro ug h the blocksB, a little clearance is allowed to preventits rubb ing. The distance bet we en th eshoulders of the shaft, XX, must be slight-ly greater than the distance between thetwo points marked Y, otherwise the as-sembling of the emery wheels on the shaft

would throw apressure on theb lock s B f r o mt h e b e a r i n graces.

I t wi l l be not -ed that when the

13"END

wheels are as-sembled on theshaft they arelocked betweenflanges. These

HA V I N G

Plan. Side and End Elevations of Light ColumnGrinder for the Small Shop or Garage, Made

from Scrap

PLANBASE

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POPULAR MECHANICS 159

forc e the 1.125-in. collars against recessedwashers, which are in turn forced againstthe inn er bear ing races. This arrange-ment locks the parts together in suchfashion that there is no end play otherthan that previously mentioned at X andY. Since the races of the ball bearin gsare free at Y and rest against the feltwashers on their outer faces, they are leftfree to properly aline themselves and, incase of need, will float in their housingsa slig ht am ou nt in either direction. Whenmounting well-fitted ball bearings, it isessential that this provision be made.Otherwise the heat generated in the shaftwhen the machine is in operation may begreat enough to expand the shaft andthrow an undue strain on the bearings.The washers are recessed on one side toprovide for felt rings, which are dependedon to prevent dirt and grit from entering

the bearings.The shaft C may be made with the pul-

ley integral from a 2-in. round machine-steel bar, or an old axle or propeller shaftmay be used and the pulley made and se-cur ed on it as ind ica ted . Wh en assem-bling the shaft, it is necessary to removeone of the end block s B. The threa ds arecut to run tight, as the load comes onthe wheel. This means that rig ht-h and

threads are cut on the right end and left-hand threads on the left end of the shaft.

When mounting the head on the col-umn, reasonable care must be used tosee that it is not cramped or warped insuch a fashion that the alignment of thebearings w il l be affected. The headis mounted 2 in. from the front edge ofthe top plate of the col um n. This spacemay be used to accommodate the rests.These are made fr om mac hi ne steel. Abar of .625-in. steel has one end forged flatand bent over at right angles: the otherend is thread ed. This fo rm s th e rest fo rthe work being ground and it is supportedin a machine-steel plate by 1 by 4 in.,having a hole in each end. K nu rl edthumbscrews are used to lock the sup-porting plates in position.

The guards for the grinder wheels aremade from 16-gauge sheet iron, fitted soas to be centered when the wheels arenew. They are supported on the blocks Bby means of an angle plate riveted to theguard and fastened to the block with acapscrew. A dj u st m en t of the guard is ef-fected by means of a slot in the angle plate.

No special provision is made for greas-ing or oiling the bearings.

Details of the Grinder Head and Wheel

Guards; Above, Photo of Finished Grinder

WHEELGUARD

SLOT

1" ANGLE IRON

DETAIL OFHEAD

8"FELTWASHER

FELT

" x 6" WHEEL" x 6" WHEEL

2" PULLEY

2 "