Another grinder build ...tracking question

[Stacy E. Apelt - Bladesmith]

I have used expandable wheels up to 8". They work well for lapidary work, and should be good for knife work as a replacement for smaller wheels. I think I have them in 4" and 6" right now.

 

[Natlek]

This is really weird way to make grinder Backwards Finally I make rotary platen attachment .I use double frame design .Frame are from hardened steel from circular saw , 3mm thick .First i use this tensioner , reworked it to push /it was pull originally / but don t work as it should .It don t push even both side ...with help of pliers will work but i found better and more simple solution .....off center M12 bolt is just right for this .Now i need to find my wheels and belt which I store somewhere two years ago

I think that you would like this .......I need more clearance for drive wheel because it will be tracking wheel .Shaft on motor have not enough length so if i use plate to mount motor on it will be very tight .....This is what I think would work perfect ...Frame / front part of motor / will sit inside in main frame /10mm thick/ so i will have more then enough clearance for moving wheel up down .Two uniball bearing make it simple as it can be....
blue is uniball bearing ...

and it works ............
from front

from side

You can see on pictures my tool arm , also finished ...Now i really need to make frame for all this parts

 

[Natlek]

Well , after two months waiting for plasma cut in shape plate I get square one So i do it my self ...angle grinder laser fiber He is a alive now ....make some sparks .
Drilling , threading holes.................no way this time , I weld everything in five minutes!
I need new bearing in small wheels , this one are dry like Sahara desert.I have to get used to tracking bolt it is to much sensitive or change it to other one with finer thread if that help because wheel is big and tracking bolt is far away from wheel.
Here are some pictures............belt speed is 32 m/s or about 6300 FPM .

Because there is not tracking wheel i can move small wheel in whatever position i like ...........

Locking mechanism for tool arm .........I didn't want to mill channel in tooling arm so I used engine valve shims ....so bolt can not make damage on tooling arm .

PS . Folder name for this grinder pictures is ....LAST GRINDER ...................and i already start to build other last one .....one inch belt grinder , something is wrong with me

 

[Natlek]

Well I just try different size contact wheels i have for now .....I will need other /longer/ tool arm for really small wheels ...........

That SKF tape hold weight I need to glue on wheel for balancing

It take one minute to full stop .....

Run perfect forward / backward without touching tracking bolt ....And one more thing ................Spring , ratchet , gas tension........forget about that .With just pull on tool arm I can tighten belt perfectly ! It run quietly like dream !
And this is my /for now/ back and forth switch I have Hitachi VFD drive but I still thinking on which grinder to use ......

Edited to add short video ..........It take me a few tries to figure out what's going on After some running time belt will start to move in side...Well tracking bolt have no spring /yet/ and that contact wheel need little more weight /which I forget to glue / and even there are very small vibration they move tracking bolt .........temporary solution are this pliers That it is guys i hope you like it

 

[Natlek]

OK guys last update ..... I won't bother you anymore . I forget that I have 2x42 belt grinder .So i don t need other longer tool arm for small wheels .I just drilled and threaded M8 in corner of tool arm and......like it
on this picture small wheel is bolted on existing hole...

in new one ..........

there are enough clearance ...........

 

[Natlek]

Well guys ..............I found one /for me personally not big/ flaws . If i try to grind on belt between wheels ,belt will simple fall from grinder .....i guess it happens because when pressure is applied belt bend and go left or right on contact wheel depends on what side is bend .Bending act like tracking , lack of tracking wheel between drive wheel and contact wheel /flat platen have price obviously ................not good but i don t need to use that kind of grinding .Otherwise grinder work perfectly . I bring this up just to let you know if someone get this route to build grinder

Hm..............now drive wheel track up and down .What if I make it /it is easy /to track left and right ? I think that will make huge difference in holding belt in place ???

 

[Hubert S.]

Is your drive wheel crowned?

 

[Natlek]

no ?

 

[Hubert S.]

I think the belt stays on the top of the crown because of a difference in tension. When there is no crown and you push on the belt during slack grinding, you apply uneven tension and the belt moves. Matthias Wandel made a video about it a long time ago. I think it is the one linked below, but I cannot watch it at the moment to verify.

I think if you put a small crown on the drive wheel, it will track better. I do not see how changing the tracking axis would help.

 

[Natlek]

I think the belt stays on the top of the crown because of a difference in tension. When there is no crown and you push on the belt during slack grinding, you apply uneven tension and the belt moves. Matthias Wandel made a video about it a long time ago. I think it is the one linked below, but I cannot watch it at the moment to verify.

I think if you put a small crown on the drive wheel, it will track better. I do not see how changing the tracking axis would help.

Thanks I understand how crown on wheel work .About tracking axis ...........I m not quite sure ..............Look this picture .When tracking is up-down...Upper side of belt want to go in one direction downside of belt in other direction because of angle on wheel ? If tracking is left-right both sides of belt want to move in same direction ? I make other test just now............I move running belt with tracking wheel in side....everything goes fine for about 3-4mm move of belt on side and then if I continue to turn VERY slowly tracking wheel .........belt suddenly want to jump out of contact wheel . I think reason was that upper side of belt fight downside of belt on drive wheel ?? Now I m lost Just to note , drive wheel and contact wheel are perfectly aligned and belt run perfectly .Measuring wheels in that position /where belt run straight/ show that wheels are almost in perfect alignment in any direction.

 

[Natlek]

Is your drive wheel crowned?

What I m trying to say is this .............I think Drive wheel ACT as two tracking wheel on same grinder where one is set to move belt right and other one is set to run belt left ??? If all this make sense?
I wonder are this grinder have same problem ?

 

[Hubert S.]

I wonder are this grinder have same problem ?

I don't think so. It looks like they are using a crowned wheel.

 

[Natlek]

OK......... I have not crowned wheel on any of my grinders and they work flawless .I just make another test on this small beast of grinder ..if i push belt between idler wheel and tracking wheel nothing....actually once i grind one convex knife there , if i push belt between drive wheel and tracking wheel belt move ....Never mind , if i decide to paint frame i will try other way to see what would happen .All i need to do is to drill just two holes

 

[Hubert S.]

I did the same test on my grinder. If I push on the belt between drive wheel and tracking wheel, the belt moves a little bit in the direction I push. If I push between tracking wheel and contact wheel, the belt wants to move in the opposite direction. Both my drive wheel and tracking wheel are crowned. In either case, the movement is not a whole lot, I do not think you could push the belt off with any force applied during grinding, or even make it move by more than an 1/8" or so.

OK......... I have not crowned wheel on any of my grinders and they work flawless .I just make another test on this small beast of grinder ..if i push belt between idler wheel and tracking wheel nothing....actually once i grind one convex knife there , if i push belt between drive wheel and tracking wheel belt move ....Never mind , if i decide to paint frame i will try other way to see what would happen .All i need to do is to drill just two holes

 

[Natlek]

I did the same test on my grinder. If I push on the belt between drive wheel and tracking wheel, the belt moves a little bit in the direction I push. If I push between tracking wheel and contact wheel, the belt wants to move in the opposite direction. Both my drive wheel and tracking wheel are crowned. In either case, the movement is not a whole lot, I do not think you could push the belt off with any force applied during grinding, or even make it move by more than an 1/8" or so.

Ok, I turn on lathe crown on drive wheel ..............Maybe , maybe little better but problem is still there .Two wheels and that is that , i think .I was thinking that i was recorded longer ...but you can see what s going on ....

 

[Jesse Latham]

Putting a crown on the tracking wheel is as simple as putting several layers of black tape in the center.

 

[Hubert S.]

Ok, I grind on lathe crown on drive wheel ..............Maybe , maybe little better but problem is still there .Two wheels and that is that , i think .I was thinking that i was recorded longer ...but you can see what s going on ....

It looks like a lot of belt movement compared to what I was getting earlier today, and I had to push a lot harder.

How much tension do you have on the belt? If I move my tracking wheel out of the way, I don't have a way to apply belt tension other than pulling on the contact wheel before locking it down. I briefly tried that just now and was getting a good bit of deflection, similar to what you show in the video. There is very little tension on the belt compared to what I normally have. I don't know whether the behavior is caused by the two-wheel setup without tracking wheel, or whether it is caused by the lack of tension. I can do another test with the tracking wheel and very little tension, but that may have to wait until tomorrow. Or run it without the tracking wheel and apply more tension before locking the tool arm using a lever.

 

[Natlek]

It looks like a lot of belt movement compared to what I was getting earlier today, and I had to push a lot harder.

How much tension do you have on the belt? If I move my tracking wheel out of the way, I don't have a way to apply belt tension other than pulling on the contact wheel before locking it down. I briefly tried that just now and was getting a good bit of deflection, similar to what you show in the video. There is very little tension on the belt compared to what I normally have. I don't know whether the behavior is caused by the two-wheel setup without tracking wheel, or whether it is caused by the lack of tension. I can do another test with the tracking wheel and very little tension, but that may have to wait until tomorrow. Or run it without the tracking wheel and apply more tension before locking the tool arm using a lever.

Don t waste time anymore .Thanks for help ! Something is wrong here ......... I started it now, an hour and a half ? after shooting that video and belt jump from wheels ....ran away from me
Edit to add....Ok it was belt , half join fall.They are too old , from my 17 inch grinder .I have one new /ordered when i was making my 17 inch wheel grinder , never used but it is not glued straight ....so no good for this testing .I need new belts and bearings for my platen wheels ....

 

[Natlek]

It looks like a lot of belt movement compared to what I was getting earlier today, and I had to push a lot harder.

How much tension do you have on the belt? If I move my tracking wheel out of the way, I don't have a way to apply belt tension other than pulling on the contact wheel before locking it down. I briefly tried that just now and was getting a good bit of deflection, similar to what you show in the video. There is very little tension on the belt compared to what I normally have. I don't know whether the behavior is caused by the two-wheel setup without tracking wheel, or whether it is caused by the lack of tension. I can do another test with the tracking wheel and very little tension, but that may have to wait until tomorrow. Or run it without the tracking wheel and apply more tension before locking the tool arm using a lever.

I was thinking I have enough tension and broken belt is problem but .....But that is not enough Done , and steady belt as rock
I used timing belt tensioner bearing for this ... grinding belt tensioner

I just cut off that plastic wheel from outside of bearing .............

 

[Hubert S.]

I was thinking I have enough tension and broken belt is problem but .....But that is not enough Done , and steady belt as rock
I used timing belt tensioner bearing for this ... grinding belt tensioner

I just cut off that plastic wheel from outside bearing .............

I'm glad the tension helped. Pretty neat system. I remember you posted something similar a while ago in a different thread, but I think that had the cam in front of the tool arm holder.