Baldor 10” 3 phase grinder restoration and modification

[RSwannabe]

So I thought I would post my most recent project. I came across a Baldor 1021w 10” grinder with cast iron stand for a good deal and picked it up. It was rough, but fairly complete, so I stripped it down, repainted it Rustoleum Smoke Gray, and installed new bearings.

 

[RSwannabe]

It is a three phase 1.5 hp grinder, and I don’t have three phase in my shop, so I bought an ATO 2hp vfd with the idea that I would incorporated into the base of the stand. I was surprised when I got it and found that it would just fit into the top of the main shaft of the stand. It’s almost an interference fit, but it did print a 3-D bracket that just holds it there at the top and prevents it from sliding down. In that position, it actually pulls air from the bottom of the stand, and exhaust it under the grinder at the top of the stand.

 

[RSwannabe]

So i drew up in Onshape and 3-D printed a switch cover plate that accepted the control panel from the VFD to mount on the switch location on the stand. And because I like my vintage tools to look vintage I also drew up and printed a cover for the control panel.

 

[RSwannabe]

I did this resto and upgrade because I had the idea I wanted to make myself a powerful variable speed belt grinder for my shop by combining a grinder like this with a belt grinder. I’ve been looking for something like one of the old Delta 6 x 48 belt Sanders to see if I could make it to a grinder like this. In my searching, I came across a complete Atlas 5010 sander for $50 that I thought might be perfect for this. It’s like a three-quarter scale delta, with all cast-iron construction, excepting the shroud which is cast aluminum. The Atlas is really well built, and I thought it would suite my desire for a vertical oriented belt grinder with a good work table.

 

[RSwannabe]

I drew up in CAD an adapter that would bolt to the Baldor in place of the wheel guard that the Atlas would mount to. I printed the early iteration in petg to test fit, with the expectation that I would then machine the piece out of metal. But then I thought well let’s see what is possible with the new engineering filaments. So then I printed it on a 45° bias for greater strength out of PAHT reinforced with carbon fiber. I mounted the atlas using this adapter, and it was more than strong enough to hold the unit without breaking, which frankly surprised me a little. But it was more flexible than I would like, so then I went to the strongest and stiffest filament I can print with, a PPA reinforced with carbon fiber in the core. I printed a third adapter using that filament, made it a little oversized, and turned it to final size on my lathe and it was more than strong enough. I was quite surprised. The sander with table is not light and it is significantly cantilevered off the mount, but this carbon fiber reinforced nylon adapter seems to be more than up to the task. I’m continuing to inspect it to see if there is any significant creep or deflection over time under load.

 

[RSwannabe]

I cleaned up and repainted the Atlas, and installed new bearings, and mounted it up to the Baldor. I also drew up and printed a custom 3.25 inch diameter by 4 inch wide drive pulley, bolted it all together, and fired it up.

 

[RSwannabe]

I reached out to Matt Blast here on Garage Journal, and he made a new wiring sticker, and a new number plate for the grinder for me which look fantastic.

 

[RSwannabe]

The good: it runs smooth and quiet, and the motor’s got lots of power at its rated rpm. The Atlas looks like it was made to mount to the Baldor and the size is just right. The tracking and adjustment of the belt on the Atlas are rock solid. The cast-iron construction quality of both units just go together like peanut butter and jelly.

I really like how I was able to mount the VFD inside the base, and incorporate the control panel in what I feel as an elegant manner. I also really like what I have learned about what is possible with these modern engineering grade filaments for 3d printing. I was able to do in printed nylon what I was sure would have to be at least machined aluminum when I started this project.

The bad: the Atlas has a drive wheel of just 3.25 inch diameter. So at the 1800 RPM of the Baldor grinder the belt on the Atlas is only turning 1530 surface feet per minute. I knew this math going in, which is why I wanted to use a three phase grinder with a VFD. I had read a lot about being able to spin a four pole motor up to 120 Hz or more without problem. If that was the case and I could spin the grinder to 3600 RPM plus, the belt speed would’ve been at least 3060 ft./min. Not optimal, but probably good enough. BUT the Baldor will not spin up to 120 Hz under any kind of load. It is an old non-inverter rated motor, and it really doesn’t want to spin much beyond 80 Hz. When you do try to spin it up to 120 it starts to get too hot too fast and bogs down. So that being in the case, I’m really not able to spin the belt on the Atlas fast enough to do what I want to do. It works, but is sub optimal. So unfortunately, at this point, this seems to be an unsuccessful experiment.

 

[ALLFAST]

The good: it runs smooth and quiet, and the motor’s got lots of power at its rated rpm. The Atlas looks like it was made to mount to the Baldor and the size is just right. The tracking and adjustment of the belt on the Atlas are rock solid. The cast-iron construction quality of both units just go together like peanut butter and jelly.

I really like how I was able to mount the VFD inside the base, and incorporate the control panel in what I feel as an elegant manner. I also really like what I have learned about what is possible with these modern engineering grade filaments for 3d printing. I was able to do in printed nylon what I was sure would have to be at least machined aluminum when I started this project.

The bad: the Atlas has a drive wheel of just 3.25 inch diameter. So at the 1800 RPM of the Baldor grinder the belt on the Atlas is only turning 1530 surface feet per minute. I knew this math going in, which is why I wanted to use a three phase grinder with a VFD. I had read a lot about being able to spin a four pole motor up to 120 Hz or more without problem. If that was the case and I could spin the grinder to 3600 RPM plus, the belt speed would’ve been at least 3060 ft./min. Not optimal, but probably good enough. BUT the Baldor will not spin up to 120 Hz under any kind of load. It is an old non-inverter rated motor, and it really doesn’t want to spin much beyond 80 Hz. When you do try to spin it up to 120 it starts to get too hot too fast and bogs down. So that being in the case, I’m really not able to spin the belt on the Atlas fast enough to do what I want to do. It works, but is sub optimal. So unfortunately, at this point, this seems to be an unsuccessful experiment.

Hello RSW,

Beautiful work and creativity!

I briefly owned ( about 3 years ago) a 1937 Baldor 1021 (I think it was a w model)) and it was a beautiful machine. It weighed about 178# !

No stand unfortunately, its footprint was massive. Anyway, I ended up speaking with one of the oldest living original Baldor employees ( a former early 70s era manufacturing plant/repair tech turned sales rep) who helped me identify the year ( the metal ID badge was partially worn out) by pictures, etc.

He related that the windings were quite special in comparison to the higher rpm models-they were designed to stay cooler during longer run times.

These 10” 1725/1800 slow speed motors were engineered to be machinist’s tool grinders, to keep from overheating expensive tool bits. They are also MUCH safer and pleasant when using a wire wheel.

Mine was a torque monster 1 hp single phase 120V. I think it was 9 amp?

Are you going to return it to the original slow speed grinder configuration ? Your hidden VFD/retro 3D switch plate creation is FANTASTIC.

I’ve since purchased a late 40s skill 10” 1 hp slow speed grinder and have been enjoying it greatly.

If you can, please share any updates on this one…it’s a beautiful machine and you have much to be proud of!

Best regards,


Shawn

 

[RSwannabe]

Hello RSW,

Beautiful work and creativity!

I briefly owned ( about 3 years ago) a 1937 Baldor 1021 (I think it was a w model)) and it was a beautiful machine. It weighed about 178# !

No stand unfortunately, its footprint was massive. Anyway, I ended up speaking with one of the oldest living original Baldor employees ( a former early 70s era manufacturing plant/repair tech turned sales rep) who helped me identify the year ( the metal ID badge was partially worn out) by pictures, etc.

He related that the windings were quite special in comparison to the higher rpm models-they were designed to stay cooler during longer run times.

These 10” 1725/1800 slow speed motors were engineered to be machinist’s tool grinders, to keep from overheating expensive tool bits. They are also MUCH safer and pleasant when using a wire wheel.

Mine was a torque monster 1 hp single phase 120V. I think it was 9 amp?

Are you going to return it to the original slow speed grinder configuration ? Your hidden VFD/retro 3D switch plate creation is FANTASTIC.

I’ve since purchased a late 40s skill 10” 1 hp slow speed grinder and have been enjoying it greatly.

If you can, please share any updates on this one…it’s a beautiful machine and you have much to be proud of!

Best regards,


Shawn

Shawn,

Thank you. I've been using the wire wheel and Atlas belt sander on the Baldor as I contemplate what I'll do. I'd like to try mounting the Atlas on a high speed Baldor to see how it would perform, but they don't make a high speed 10". They do maker a high speed 8", but it only is 3/4 HP. It is also too narrow I think to leave enough shaft to mount the 4" drive wheel. Baldor does make high speed 8" and 10" buffers that might work. So I'm keeping my eye out for one of those at a good price local to me. Until then, I'll likely just keep using this one as it is. I also picked up a vintage Delta Rockwell 6"x48" sander I want to restore and hot rod for metal use as well. I'll post on that when I get to it as well as any updates on this project as well.