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Rockwell Belt Sander

double

Aluminum
Joined
Oct 12, 2003
Location
Greeneville Tn. US
My old retired machinist buddy gave me a 6X48 Rockwell belt sander.After replacing all the bearings and fixing the rollers I need to know what to power it with. Ive got an old (probably wash machine) motor 1/3 HP with a 2" pulley. It turns it fine with just the lower pulleys turning but havent installed the belt yet. Do you think this motor is big enough or do I need to scrounge some more. TIA.........Jack
 
These belt sanders need more than 1/3 HP. You will stall it on the littlest parts, if it will reliably start at all. 1.5 HP would be good, 3/4 HP would be barely adequate. Delta's home grade 6 x 48 comes with a 1 HP motor and the industrial grade 6 x 48 comes with a 1.5 HP motor.
 
I just took a look at my Rockwell series 31-520 6X48 sander and it currently has a Craftsman 1HP 1725 RPM motor wired for 220V.

I don't know what size pulleys are on it as I didn't remove the cover.
It has never stalled out on me.

It has deburred thousands of parts.

Les
 
1/3 HP is on the edge of not enough. I do have a old (maybe 195?)Craftsman belt & disk 6 X 48 equiped with an Emersion capacitor start 1/3 HP 1725 rpm motor, with the smallest pully you can buy for a 1/2" shaft (I think it is a 1-3/8" IIRC)on the motor and about a 3" pully driving the sander. It is an old motor and open face so I made a deflector for each end to sheild it some from the sawdust and metal dust I make while sanding. I have used this setup since 1975 and estimate it sees only about an hour a month use. I can stall it if I push hard on the object being sanded. For a hobbist I think it's okay but if you do a lot of sanding I'd guess a 3/4 HP would be better and even more HP for production work. With the more recent way motors are advertized regarding HP, I'm as confused as the next fellow. From a performance standpoint I prefer an old 1/2 HP Induction Repulsion motor to a new 1 HP motor. Motor amps are probably a better indication of the power you can expect than some HP ratings. Or compute the HP by using the equation volts x amps = watts and 746 watts is a HP.
 
1/3 is low but it depends in part on the belt speed. I realize this is a metal forum ... but if you are setting it up for wood you'll want around 1500 to 2000 sfpm and 1/3 might work. If for metal, 3000 to 4000 sfpm and 3/4 hp is about the minimum. If you plan to hog out a lot of material at 4000 sfpm, 2 hp is a better choice.

Bob
 
We have two Delta 6x48 belt sanders both have 1.5 hp motors. A 1/3 hp motor is too small. The advantage of the large motor is that you can really push and remove large amounts of material with a course belt and never stall the motor. That is why you have the big sander, putting a very small motor on it means you will not have anything nearly as useful as it was designed to be and in some ways it will not be as safe since bogging down etc. is like having a dull saw blade or other dangerous situation.
 
I have one with a 2HP motor and I can stall it sanding the end of a piece of 2X3 X .120 steel tube with a 36 grit belt. If I ever have to fix the motor I'm going to replace it with a 3HP 3 phase motor.
 
I say if it is stalling out with that size motor, you are using the wrong machine for the job.

When I want to square something up or really remove metal, I use the Apex 16" disc sander. It has a 1HP 3PH 1800 RPM motor on it. I even do hardened A-2 on the thing. It just loves to eat metal.

I use the belt sanders for lighter work.

Les
 
You're right. Normally I use a disc. Some times it has the wrong grit disc on it so I pop a coarse belt on the 6X48 for a quickie.
 
Ken Thanks a million for the link. I wish I had that when I had this thing in a million pieces. Ive come across a 1HP but seriously we tried it last night with the little 1/3 and it done a good job. Now I know what bolts to the housing and why it has a degree plate on the side. I didnt get the adjustable plate with it. Thanks again...Jack
 
double, I'm happy for your success with the 1/3 HP motor.
I want to add a comment/caution about the 6 X 48 sanders. My old Sears sander does not have a removable platten like the Rockwell so running slower and on the lower end power wise is perhaps a way to ensure a longer life for the cast platten. Moving the work around, back and forth across the belt as well as up and down the length of the sanding surface, will keep heat and wear to a minimum. Over the years of reconditioning power tools I have had 5 of the Rockwell sanders (I have one to rebuild now, this one will stay in my shop when I get it done)none of them came to me with a motor but all of them did have a common condition - the plattens were seriously worn. They had hollowed out spots (wear depressions) near the work rest. I suspect they were abused by someone holding the work in one spot, pushing too hard, for too long with enough motor power to allow this to continue until it caused the dips in the platten. Quite possibly they were used for production deburring. Maybe unskilled labor interested in numbers of parts done and could care less about the proper care of the machine (speculation on my part). Getting anything close to square is impossible with such a condition. So not having a way to regrind them (at least 1 was too far gone for a regrind) I replaced them. IIRC @ about $109.00 each in ~1980. I'm almost afraid to see what a platten will cost today for the sander I want to rebuild. Somebody on this forum just bought himself a blanchard grinder, maybe he could use this one I have for practice - hint, hint. Another thing about it is that once you wear the platten (scooping out depressions) the belt stretches at these locations making belt tracking more difficult and the outcome from this is the belt wandering off and cutting through the sheetmetal side cover (if so equiped) or the aluminum cap cover I have repaired a few of these too.

Treat her right and she will last a long time, enjoy your sanding.
 
Great post Steve.

I will have to take a look at the platten on mine. The belt tracking can be kind of finicky to adjust and the cover has been cut by the belt in the past.

Do you know who made the Monkey Wards line of 6X48 sanders? I have one of those also and I wonder parts are available.

I don't have to be hit up side of the head with a 2X4 to catch a hint.
As soon as I get proficient on the blanchard I could try grinding that.

Les
 
Les, my first thought was Power King but I'm not sure. You caught that subtle hint!

Doug, I tried making a platten once of 3/16 parallel ground plate welding 1/4" by 3/4" about the edge. With the wrapage I got from my non-professional weld job I was back to square one - in need of a grinder to flaten it out. I wasn't awear of the stamped replacement option, I will look into that. Thank you. I really didn't think about getting one bent up - another good option, thanks.
 
Ive got a Gremlin this thing I cant kill! Ill adjust the tracking and watch it run "forever" then shut it off and go back a lil later and that crazy belt travels one way or the other. I guess thats why the outer guard is cut up so much. Is there a way to tram this thing where itll be still? Theres a little sloppage in the top rollers Should I try to shim them a little tighter? Thanks Jack
 
re paper backed belts
We used to make wood boxes and had a big 22 inch wide sander that used paper belts, but one false move and they were trash, went to cloth belts,
 
Mine has done that since it was new (1979). I blame it on the belt getting hotter and expanding more on one side than the other, then shrinking back when it cools, with the attendant tracking change. Does it with 3M belts, and Klingspor belts. I never tried cheap belts or paper belts. The drums have little to no crown, perhaps some crown would help.
 
I have a 6x48 Delta belt sander and I always back off on the belt tension after I use the machine if it is going to be a day or two before I use it again. If I leave tension on the belt is stretches enough to effect how it runs. I use Norton cloth backed belts. As a general rule I wear a full face shield when I use that sander as it is kind of a thrill when a belt breaks up. I haven't been hit in the face with a belt but I figure a course grit would give you quite a rash if it hit you. It does a number on the occasional finger nail or finger that gets too close.
 








 
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