2x72 belt grinder build

[extropic]

Very nice Randal.

I got a chuckle out of the cat, when he/she wakes, if he/she steps to the wrong side of that box . . . Yeow!



Looking over the machine, I offer a couple of suggestions. Regarding the square tube (to be removed), rather than removing it, consider using it to mount a rack to store spare belts and/or other accessories. Regarding the filter for the VFD cabinet, add a PVC fitting to add a 90° ell so gravity works for you. Lots of options as to size and configuration.
YMMV

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[rabler]

Very nice Randal.

I got a chuckle out of the cat, when he/she wakes, if he/she steps to the wrong side of that box . . . Yeow!

Looking over the machine, I offer a couple of suggestions. Regarding the square tube (to be removed), rather than removing it, consider using it to mount a rack to store spare belts and/or other accessories. Regarding the filter for the VFD cabinet, add a PVC fitting to add a 90° ell so gravity works for you. Lots of options as to size and configuration.
YMMV

That whole litter of kittens has been amusing. They are about 5 months old now.

The square tube section is less than ideal as belt storage. For one thing it would make the running belt harder to remove. Another issue is when the grinder rotates to horizontal, that tube would be vertical and the belts won’t hang right.

 

[extropic]

The square tube section is less than ideal as belt storage. For one thing it would make the running belt harder to remove. Another issue is when the grinder rotates to horizontal, that tube would be vertical and the belts won’t hang right.

D'oh!

 

[rabler]

Some specs, for anyone curious about trivia:
I'm running a 6" drive wheel, with an inverter 2HP motor, rated 1750 RPM motor. I'm using a 3HP Teco L510 series VFD. Plan was to allow
45 Hz to 100 Hz, giving a range of 2060 to 4580 SFPM. What I've seen suggests 3000 to 5000 SFPM is ideal so I'm a little slow. It's a cheap (Boston Gear/WEG) inverter motor so I'm not keen on pushing it too far.

There is some merit in running it much slower to get the initial tracking aligned if it's completely out of wack. I reprogrammed my VFD to go down to 5Hz when I was initially playing with that. But then the useful grinding speed range is represented by about 1/3 of a turn of my current cheap potentiometer. If I leave it with that range I make look into a multi-turn pot, although reducing the acceleration time to something very small would also help, and should be feasible with the minimal mass to spin up.

Anyway, would be easy enough to change out the drive wheel if I need something significantly different. IIRC I had calculated a 6.5" wheel would be close to ideal, but 6061 tube stock was either 6" or 7" in short sections from McMaster. I'll see after using it if a 7" wheel is more attractive.

 

[rabler]

Some delay as I had to drive a horse out to Massatuchets last week, about 40 hours on the road over 4 days pulling a good sized gooseneck trailer.

Got the belt grinder painted before I left so the paint had a few days to set up. Made a small panel for a switch and potentiometer going to the VFD in the back cabinet. Put back together and test run. Two of the idlers running a little hot. I believe the central shaft that mounts the bearing for the idler below the platen is a hair too large causing the bearing to be tight. A little time with emory cloth will fix that. The tracking adjust idler on the tension arm is also running warm, I think that one is too much axial pressure on the bearings and needs a shim.

Still need to epoxy the glass to the platen, and filter over the VFD. Also just ordered a compression spring from McMaster to keep the tracking adjustment from drifting. I did drop the VFD deceleration time to 1.5 seconds, which gave me an over voltage error on deceleration, so I upped the deceleration time to 2.5 seconds. Tomorrow I'll set the parameters to allow it to temporarily maintain speed on acceleration/deceleration on error, so that it doesn't tend to error out and instead is more self-regulating.

 

[rabler]

@rabler, that a nice bright workspace. I'd be eager to get back in there too!
Brian

The semi-gloss white walls and high gloss metal ceiling really help with making it brighter. That was definitely the right thing to do. Just need to put a few things on the wall to personalize it.

 

[rabler]

Got this belt grinder/sander all done. Quite happy with it. I did have to make a jam nut for the tracking adjustment, the classical spring solution didn't stop it from drifting. Could be some vibration in that pulley/idler, some work on balancing it might help, but it is not obvious.

I'm attaching the plans both in PDF and in FreeCad in case anyone wants to use them as a starting point. Overall I'm quite happy with this. Only design change I would make is to extend the base plate that is under the motor forward about 2" as it would balance better. A non-issue with the way I have it mounted but not ideal. I did have to make a bit of a cutout in that baseplate to handle pivoting to horizontal, and the motor also hangs below that plate in the horizontal position so that plate isn't suited for a direct benchtop mount. While I discussed adding a side mounted disc sander, decided that was too much of a compromise to do elegantly. If anyone has questions about more detailed design points I'm happy to discuss.

 

[rabler]

A few more of the PDF files, as the limit is 20 attachments per post ...

 

[wachuko]

Just came across this thread… interesting…

I ordered the plans from Jer yesterday… sigh…

Inch plans - https://www.etsy.com/listing/969297008/inch-plans-gen-2-tilting-belt-grinder

 

[Just for fun]

Thanks Randle!