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mklotz70 belt sander build


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  • 4 weeks later...
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Figbuck has had discs for several weeks now. He's still posting, so I'll assume the brakes are still working :) Anyway.... I was a bit frustrated with the motor situation. I tried the pool motor on 220v and it still wasn't any better. I've since figured out that it has a RUN capacitor, not a start capacitor. I tried another 115v 3450rpm 1.5hp motor(new) and it wouldn't do any better.....so I finally just decided to make it a 220v grinder. It's going to be a bit of a bother for now, but oh well. I need to get busy on the Z'd control arms.....so I guess I'll be working on more than one project at a time for a bit. :)

 

Here's how the 3hp motor worked...WOW! In the final vid...the belt speed is 6880sfpm....not the 8000 I thought. The step up ratio is 1.33 to 1.

 

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I've saw something similar to this, but done with a hinge and wood. I've been thinking about this, mulling it over for quite some time. I finally went to Home Depot to see what my options were and this is what I came up with. Certainly not the cheapest...over $23 for these parts, not counting the switch. Anyway....I think this is going to work out exactly how I wanted it too. :) I started with the 15A swtich, but when I switched over to the 3hp motor, I had to upgrade. Just thought you'd like to see how much beefier the 20A switch is. What I'm creating here is a safety switch. You can't accidentally turn it on...you have to poke your finger through the hole. To turn it off, you simply hit the cover anywhere. :)

 

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Somewhat important note:

Steve M brought up the switch rating. A true 3hp motor would require a bigger, better switch than the 20A one I'm using. Absolutely! But...this is a cheap HF motor with a 12.26A rating and a 14.02 SF(service factor) rating. It's not a true 3hp, but it does the job nicely on here. Even if I end up changing the switch out to something different, I'll leave the previous info up because it's still a really nice way to do a 115v switch :)

 

Steve....maybe you can put some links or info up about how to figure the switch rating for any certain HP of motor.

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Talked to my bro(journeyman electrician-commercial) about the switch. He said the switch is fine because the motor has it's own thermal overload. So, I guess what it comes down to is just like the rest of my project threads...follow at your own risk and make your own decisions :). I'm going to use the switch for now since I already have it. I'll keep my eye on it and I'll upgrade it at the first sign of trouble :)

 

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I got started on the platen. It will be removable, but I doubt I'll have much need to take it off. I want it as long as possible. In hind sight, I should have made this to use 2x72 belts. I thought they were 2x60, but they're actually 1.5x60. I might have gone that route because the large platen wheel I used was not 2" wide. I know I went with the 60" to help keep thing compact. Again, in hind sight, It would not have been significantly bigger with the 72" belt.

 

When I machined the width of the platen, I simply put a 3/8" cutter in the mill and touched it to the back of the vise. Since the plate is 3/8" wide, this centered the mill on the platen's gusset. I ended up about .024" off center, but it's certainly close enough for this project. I should have clamped the platen to the gusset better before tacking....there's a gap...oh well. :) At this point, it's not as much about getting it done perfectly as it is just getting it done!!

 

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*****IMPORTANT NOTE!!!!!*****

 

The switch above WILL NOT WORK SAFELY WITH A 230V MOTOR!!!

 

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Steve M pointed this out thankfully! My bro was giving me advice on what to use, but I must have missed telling the part about the motor being a 230v motor. I was giving him amp ratings and such....as soon as I told him that it's a 230v motor, he came up with the same switch as Steve M was cool with..anyway.....

 

Here's the prob with that switch and a 230v motor. There are two legs of 115v going to the motor. With the current switch, only one leg is being switched on/off....leaving the other leg to just feed into the motor, where it may/may not safely terminate. If there's any kind of path for voltage, it can either burn up(worse case) winding or create a potential shock hazard. Since I'm going to be using this for metal grinding, there's a distinct possibility of creating a voltage path in the motor. This will make a great switch for a 115v project, just not this one. :( I'm an electronic tech by trade and really should have noticed the second leg problem. I've been doing it for about 29 years and I've hated it for about 28 of them! LOL I rarely do electrical and trust me, there's a huge difference between them. The basics are the same, but you have to switch thinking modes between them. Black to me is ground....in electrical it's the hot...wtf?? :)

 

So...a bit of digging on Grainger and I found one that both guys agreed on right away.....so it's on order, along with the enclosure at the top right of the page.

 

 

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I figure I'll leave the other switch info on here since other guys building their own grinders will use 115v motors. Here's a shot of the box part numbers from Home Depot.

 

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  • 4 weeks later...

I put some more time into it yesterday. I had some grief with the wiring, but that's figured out now and working right. I ended up having to replace a $70 circuit breaker in the house panel in the process. :( But, the old one that wasn't tripping correctly is now gone...yea!

 

First two pics are of the switch box and housing box in case someone wants to order the same.

 

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I was looking at some vids on youtube of another guys belt grinder. He said that there needed to be some tension where the belt goes over the platen. He wanted 1/8", I didn't think it needed that much, but I did tend to agree that it needs some. So, I put two pieces of 1/16" sheet in as spacers. By using the 2x1/8" bar stock clamped to the rollers, I was able to hold the platen in the same plane as the belt and with just the spacing I wanted. It worked out perfectly! The rest of the pics are of fabbing up the spacer and mount for the platen. As you can tell, it's removable.

 

 

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video walk around(same as above pics)

 

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...dang pic limit! lol

 

You might notice in the 7th? pic above that I moved the entire grinder back a bit on the main plate. I wanted more throw on the belt tensioner and that was about the only way to get it.

 

The grinder vids I mentioned above.....here's a link. He's got about 7 vids of his grinder and walks through dimensions on it. It's way simpler than this one, but way slower. I think a lot of guys would be more tempted to build one like his. :)

 

 

 

 

....but this is about my grinder :)

 

 

I started making the tool post. I think it's going to come out just right and give me a perfect 90deg. I've got more of the heavy bar stock, so I can make something different later....as in an adjustable one....but I need to get this dome enough to use so I can get on to other projects.

 

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Very cool Mike. We run the crap out of those belt sanders at work, and yes, they are spendy. I watched the vid and noticed the bandsaw in the background. I have the exact same one.

 

When you go into production on these, I'll take one,lol.

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Thanks! No production on this one....way too much work to build. My buddy Dave(a100addict) had an awesome idea about another design just after I started building this one. I was far enough in that I didn't want to change at the time, but I've started the CAD work on it. Here's a sneak peak at the platen assy. It's already changed slightly from this, but it will give you a good idea. :)

 

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Thanks. :)

I'm expecting this next design to be able to run on a 1hp motor. I won't have it run as fast either. Holy Cow does 6000sfpm + create heat quickly!!! ....and I can run over 10,000sfpm! If I slip, I'll grind off a finger before I can flinch!! LOL

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Thanks :)

I drew most of that at work. I showed a co-worker what I was doing and how much I enjoyed doing the CAD work.....he said I should get a job where they'd pay me to do that............I said "I've already got one!" LOL!!

 

As my as I hate my job.....there are nights where I get to sit on my rear for 3-4 hours and play with stuff like this. Funny thing is.....I make more than a lot of CAD designers. I'm a professional CAD designer!! :)

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I clamped up the tool rest and tacked it in place. Welding it caused an expected warp in the plate. I probably could have compensated for the slight skew from 90 deg when I did the final machining of the top surface, but it's really friggin close......and this grinder is about high rate of removal...not extreme precision! :) I'll see if I can get the vid edited and up soon.....it's a metal removing monster!!!

 

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I clamped up the tool rest and tacked it in place. Welding it caused an expected warp in the plate. I probably could have compensated for the slight skew from 90 deg when I did the final machining of the top surface, but it's really friggin close......and this grinder is about high rate of removal...not extreme precision! :) I'll see if I can get the vid edited and up soon.....it's a metal removing monster!!!

 

 

 

Did you machine before or after welding? After is best. :)

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both. You can see the difference in surface finish. I machined it rough...put it together, welded....first pic against the ruler shows the warp...machined...nice finish....second ruler pic shows it flat :) It was rough hot rolled which is why I machined it the first time.

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  • 2 weeks later...

Thought I'd share some more CAD work on the second version......but this will be the last of it. My buddy came over and refreshed my memory on his idea for using plate....after a bit more brainstorming, this design is getting scrapped. I can reuse some of the parts for the next one, but most of it will not be used. I thought you might like to see how far I got with it. At least it looks kinda cool :)

 

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Since I tend to like to show the evolution and progression of projects, I guess I'll post up Ver3 as it gets created. I may not show quite all of it until it's ready to cut, but I will finish up on Ver1. :)

 

I can't find a way in my CAD program to do a constrained belt feature. I know SolidWorks will do it. I had to find an alternative way to do it. Once I had the physical measurements, I recreated the same thing in CAD and went from there. I'm liking the new design even better. I think it will be way cheaper. We're hoping to be able to make these available as kits and as finished units(for those that don't weld) for waaaay less than the $800 the KMG grinder goes for. Probably be at least a few weeks before I can submit for quotes....got other projects that need attention :)

 

The motor pics are just me checking the CAD print to make sure I got it right. I always think it's cool to print out a 1:1 and have it perfectly dimensioned!

 

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  • 1 month later...

Now that I look at those CAD drawings, I realize just how much that design has changed! I'm sure pics of the new design will come at some point....just not yet.

 

Anyway....posted a vid of the grinder in action. :)

 

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