Help with belt grinder tracking - general design

It's a Reeder, not a home built one, so it's certainly possible you've seen it somewhere on YouTube. I don't have a YouTube channel.
 
There is my setup before/after. I took bearing housing part from bike hub, removed outside part where spikes are connected, and shaped it with angle grinder with flap disc. Use face mask and eye protection, aluminum dust is not what you want to breathe.
https://imgur.com/JvrULqd
https://imgur.com/eK1z7jV
https://imgur.com/gF7jkhP
https://imgur.com/9RQeA6b
As you can see, I have driving wheel made from plywood. It also have crown, made in place after assembly, with files, sandpaper, angle grinder. It cost me literally nothing. All grinder was made with that in mind, how to make stuff without big spending. It is doable.
Crown your tracking wheel, flatten your idlers and you should be good to go.
 
lynx85 said:
Crown your tracking wheel, flatten your idlers and you should be good to go.
Click to expand...
yes you are right, and bearings as iddler wheels is genius :D
Stacy E. Apelt - Bladesmith said:
Also, try more tension spring pressure on the belt.
Click to expand...
maybe i could try a stronger spring

but anyways, this morning i made huge improvements because of the help you all gave me!!! thank you guys very much!
i gave the tracking wheel a crown with tape, and ¨flattened¨ the iddler wheels low spot with tape also, and got it to work :), not perfect but is an improvement and im happy.


https://imgur.com/QJ7DWIl

as seen in the video, ive got it to work but my tracking wheel needs to be fairly angled towards the grinder body for the belt to be centered with the grinding plate, maybe with some tweaking i can get it to be more parallel.

and also, with just a few minutes running the bolts head get kind of hot, if i touch them for 5-8 seconds it starts to burn my fingers, is this normal??

https://imgur.com/a/ZozPsN3
 
Hot bearings is not normal. I use bearings for idlers, it was temporary solution but here I am, year later. I usually work with belt speed at 20m/s @50Hz, sometimes if I feel the need, I turn VDF to 75-80Hz, which gives me 30m/s (almost 6000sfm). At that speed bearings are louder and start to get hot. Not that I can't touch them, no. I know that there are variations in the same size, dirt cheap bearings usually have lower speed rating. Item names may vary, depending manufacturer, but high speed bearings is what we want.
 
If the bolt is getting too hot to touch you may be overheating the the wheels. This may cause them to warp which will cause your tracking to go cattywampus. You should probably go to high speed bearings. They aren't that expensive.
 
lynx85 said:
Hot bearings is not normal. I use bearings for idlers, it was temporary solution but here I am, year later. I usually work with belt speed at 20m/s @50Hz, sometimes if I feel the need, I turn VDF to 75-80Hz, which gives me 30m/s (almost 6000sfm). At that speed bearings are louder and start to get hot. Not that I can't touch them, no. I know that there are variations in the same size, dirt cheap bearings usually have lower speed rating. Item names may vary, depending manufacturer, but high speed bearings is what we want.
Click to expand...
My specs are 1500r motor, 7 inch drive wheel. In the video im at 50hz that would give me 13-14 m/s, seems kind of low 🤔. 75-80hz would get me to 20m/s.

My bearings are skf 6204 2rs, these are the only ones i could get in my country. Maybe theyre not suited for high speed 🥲. Although Is the Bolt head that gets hot, bearings seem Fine but i should check them after a long grinding session.
 
tim37a said:
If the bolt is getting too hot to touch you may be overheating the the wheels. This may cause them to warp which will cause your tracking to go cattywampus. You should probably go to high speed bearings. They aren't that expensive.
Click to expand...
Searching online these are the specifications of the bearings im using. I dont know if theyre ok or not. Can you point me which bearings Will be apt for high speeds with those measurements?

6204-2RS SKF 20X47X14mm
Dynamic Load Capacity: 3,000 lb. Static Load Capacity: 1,500 lb. Max. RPM: 20000 Operational Temp. Range: -40 Degrees to 212 Degrees F
 
3,14 x 0,047 x 20000 / 60 = 49m/s. If my calculations are correct, these bearings can withstand almost 50m/s speed. Looks perfectly fine to me to use even bare, like in my grinder setup.
Another reason for bearings to get hot is if they are under tension. Not load, but side to side tension. Do you have sleeve between both bearings, inside that grilon wheel? Is it repurposed part or did you order it to someone to make it? That sleeve (or calibrated tube, or what is it's name) is designed to interference fit, one bearing shoulders against the wheel, another just floats, for lack of better name. When you torque that bolt, then bearing inner races and sleeve is what is being torqued. Bearing outer races and wheel have interference fit. That is, if you have that sleeve. If not - there are torqued preload on all bearing and heat from working.
 
lynx85 said:
3,14 x 0,047 x 20000 / 60 = 49m/s. If my calculations are correct, these bearings can withstand almost 50m/s speed. Looks perfectly fine to me to use even bare, like in my grinder setup.
Another reason for bearings to get hot is if they are under tension. Not load, but side to side tension. Do you have sleeve between both bearings, inside that grilon wheel? Is it repurposed part or did you order it to someone to make it? That sleeve (or calibrated tube, or what is it's name) is designed to interference fit, one bearing shoulders against the wheel, another just floats, for lack of better name. When you torque that bolt, then bearing inner races and sleeve is what is being torqued. Bearing outer races and wheel have interference fit. That is, if you have that sleeve. If not - there are torqued preload on all bearing and heat from working.
Click to expand...
This
 
lynx85 said:
3,14 x 0,047 x 20000 / 60 = 49m/s. If my calculations are correct, these bearings can withstand almost 50m/s speed. Looks perfectly fine to me to use even bare, like in my grinder setup.
Another reason for bearings to get hot is if they are under tension. Not load, but side to side tension. Do you have sleeve between both bearings, inside that grilon wheel? Is it repurposed part or did you order it to someone to make it? That sleeve (or calibrated tube, or what is it's name) is designed to interference fit, one bearing shoulders against the wheel, another just floats, for lack of better name. When you torque that bolt, then bearing inner races and sleeve is what is being torqued. Bearing outer races and wheel have interference fit. That is, if you have that sleeve. If not - there are torqued preload on all bearing and heat from working.
Click to expand...
here is a picture of my wheels assembly

https://imgur.com/a/oKc8ZhJ

from right to left is, BOLT - WASHER (ONLY TOUCHES INNER RACE) - BEARING - GRILON WHEEL - BEARING - WASHER (ONLY TOUCHES INNER RACE) - LOCKING NUT - PLATTEN - LOCKING NUT

i dont have anything inside of the wheel between the bearings, i think i understood what you mean but im not sure, i need to put a turned cilinder between the inner races of both bearings inside the wheel?

here is a picture of the wheel without bearings, i bought them separately and pressed the bearings on the cavity. i torqued the assembly with the locking nut just until it moves freely with no play.

https://imgur.com/lFNhOU1
 
taviii11 said:
here is a picture of my wheels assembly

https://imgur.com/a/oKc8ZhJ

from right to left is, BOLT - WASHER (ONLY TOUCHES INNER RACE) - BEARING - GRILON WHEEL - BEARING - WASHER (ONLY TOUCHES INNER RACE) - LOCKING NUT - PLATTEN - LOCKING NUT

i dont have anything inside of the wheel between the bearings, i think i understood what you mean but im not sure, i need to put a turned cilinder between the inner races of both bearings inside the wheel?

here is a picture of the wheel without bearings, i bought them separately and pressed the bearings on the cavity. i torqued the assembly with the locking nut just until it moves freely with no play.

https://imgur.com/lFNhOU1
Click to expand...

Inner sleeve needed.... Yes. Or just make sure you are not over tightening your nuts.

Just for an experiment, loosen them so they are just snug. Tight enough to keep the assy together. Run it again, is it Hot?
 
Try to leave little play and try again. And make sure that when you torque outside nut, it doesn't turn bolt and make more tension on assembly. I would try to run it with open play before buy more parts.
 
first of all thank you guys for taking time for helping me.

Crag the Brewer said:
Inner sleeve needed.... Yes. Or just make sure you are not over tightening your nuts.

Just for an experiment, loosen them so they are just snug. Tight enough to keep the assy together. Run it again, is it Hot?
Click to expand...
they are like that right now, just tight enough to keep the assembly together, if i lossen them just a little bit it rattles.

i would try to make some inner sleeves then, the bolt axle is 20mm, i have steel tube lying around 25mm outer diameter - and 21mm inner diameter, if i cut it the same lenght that of the space between the bearings inside inner races would that be ok? or the inner diameter of the sleeve would need to be exactly 20mm?
 
taviii11 said:
first of all thank you guys for taking time for helping me.


they are like that right now, just tight enough to keep the assembly together, if i lossen them just a little bit it rattles.

i would try to make some inner sleeves then, the bolt axle is 20mm, i have steel tube lying around 25mm outer diameter - and 21mm inner diameter, if i cut it the same lenght that of the space between the bearings inside inner races would that be ok? or the inner diameter of the sleeve would need to be exactly 20mm?
Click to expand...

You generally want a slip fit over that inner axle. Idk your capability? Don't make it too loose.

Think of it as a sandwich. When you tighten the nuts on each end, the inner race of the bearing has clamp force against the inner sleeve, and that sleeve then is clamped the the next inner race, and then the following nut. All squeezed together, and the bearing spin freely.


Unfortunately heat causes plastic to expand, Alot.
So we might have that as an issue as well.


As a side tangent.... I heard skateboard wheels make good, cheap rollers.
Maybe you can find a used, unwanted one
 
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