Need help on bms250

[PAmizerman]

I've been running my sharpener for 5 years now. I started having trouble with the blade advancer.

I took two videos. How is everyone else's set up? Far tooth or close tooth video?

I had it set up in the" close tooth" position
All this time and it never drug. Now the grindstone is hitting it.

In the "far tooth" position everything runs smoothly but the threaded rod will hit when I put the hood down. I'm honestly thinking about just cutting some of the rod off. 

Am I missing something? 

far tooth - YouTube 


close tooth - YouTube

[terrifictimbersllc]

Mine is like your "close tooth", the 2nd video. The pusher pushes that tooth which is about to be ground.

Seems like the motor/wheel assy is falling too fast at one point, maybe I'm mistaken. My pusher escapes in time. If speed is turned way down just enough to keep some motion going the motor should be always under control never free falling. If it is falling,  then pushing the farther tooth won't help, the action during grinding won't be right. 

[Crossroads]

Check your bearing that rides the cam. If it's failed, it could affect the timing. 

[Andries]

PA; what's changed in the last five years? 
It was working as it should, then things didn't because of an adjustment, or a part replacement, or .  . . ? 
My BMS250 is set up to push on the far tooth, which allows the lid to close without having the push paddle arm get in the way. Something isn't set up correctly - pulling out a hacksaw may not be a wise move.

[JoshNZ]

Is it a worn band with lower gullet or something? You could try raising/lowering the band in the jaw to put the stone descent onto a different part of the cams curve.

As above, need to figure out what's changed.
For what it's worth my sharpener diff model, the pusher head barely escapes the stone. I bought it second hand it has been tweaked into a slight smiling banana to aid in this clearance.

[PAmizerman]

All bearings are fine.
I changed nothing. I sharpened 20 bands the same day. No problem then it started this. I pulled the book out and did a realignment. Still hitting the pusher. 

[MattM]

Check your bolts that position the pusher motor. They're in slots and if that moved to the left it could cause your problem.

[Andries]

Last month, I ran into a deal on a BMS 250. Electrical switches not working, the CBN wheel was worn out and the oil bath looked like the Alberta Tar Sands. It's a steal of a deal, but a "project" too.
So, @PAmizerman here's how my sharpener cleanup might relate to your machine's inclination to grind the push paddle to bits.

When I tried to move the band rest pins all the way up, the threads were crusty with crud.

The height adjuster chain underneath wouldn't move more than two inches because it was clogged up too. I found that the push paddle had grinding marks on it and the end of push arm was bumping into the cover, like yours. After cleaning up the entire machine and filling the oil bath with mineral oil, the height adjuster was cranked all the way down. The clearance between the wheel and band clamp is about 1/8". The band was placed in the clamp and height was adjusted much further down than it was before.
. 
Problem solved. Pusher arm cleared the cover, the CBN wheel didn't hit the pusher paddle and we're in business. Now I have to fine tune all my locally sharpened bands to the WM profile.
It was -45° C the other night, so the woodstove will be working while I'm sharpening. 
Hope this helps.

[PAmizerman]

@Andries I keep my sharpener clean.
It is common for filings to collect on the sprockets and tighten things up. 

I did a complete realignment thinking maybe something was off. 

I may have found my problem but won't have time to work on it till Saturday. 

I found out the feed motor started running in reverse. I'll see what's up with that.

[Peter Drouin]

Be sure to clean under/ inside the clamp so the blade is down all the way.  I have had build up there in the past. Holding the blade up just a whisker.

[Andries]

Peter; mine sure was blocked up. I'll bet the previous owner hadn't ever cleaned the sharpener at all.
.
PA; when I first opened the control box, it seemed far more complex in there than it needed to be. Two motors, one of them a variable speed, and an oil pump - what are all these relays and circuit boards and . .  . Oh, yeah. Made in Poland. 220v. and others are 110v. and yet others are 12v. But, a motor that reversed itself somehow? I'm not doubting what you're seeing, but instead of a circuit schematic you may need to call an exorcist? 

[YellowHammer]

Mine did that.  The big 3/4 bolt riding on the bearing had moved and was causing a lack of clearance between the pusher and the grind wheel and causing a notch to be ground into the pusher. I would check that.  

[terrifictimbersllc]

 

 
Does anyone understand the function of the cam brake pin number 27, could this need lubrication or other maintenance, does it have a role in slowing the descent of the head. on my sharpener 27 is a spring loaded approximately 3/8 diameter pin pressed against the back of the cam plate. It's naturally always oiled, I guess it must have an effect on dampening momentum. If it is not pressed tightly against the cam plate  I would guess that it should be.

[Stephen1]

I had it happen when the student was sharpening, he had adjusted the next blade to the CBN wheel as he always had , and then adjusted the pusher to get the wheel to meet the blade. He ended up going up with the blade instead of going down to meet the wheel. Took me a while to figure it.   We sharpen other blades for customers so we are always adjusting wheel and pusher to match.   
 KISS problem solving. 

[Crossroads]

Have you had the motor off and swapped the leads? I see in the video your cam is rotating clockwise. In the WM video it is rotating counterclockwise. 

[Percy]

Have you had the motor off and swapped the leads? I see in the video your cam is rotating clockwise. In the WM video it is rotating counterclockwise.

Good eye Crossroads. 👍👍
I'll bet anyone a pail grits, this is the problem....

[PAmizerman]

Have you had the motor off and swapped the leads? I see in the video your cam is rotating clockwise. In the WM video it is rotating counterclockwise.

That is the motor I was referring to that is running backwards. I'll look into it Saturday 

[terrifictimbersllc]

Mine goes CCW 

[Crossroads]

Have you had the motor off and swapped the leads? I see in the video your cam is rotating clockwise. In the WM video it is rotating counterclockwise.

Good eye Crossroads. 👍👍
I'll bet anyone a pail grits, this is the problem....

I need to give credit where credit is due. 
Gmmills contacted me last night and point it out. 

[Percy]

Have you had the motor off and swapped the leads? I see in the video your cam is rotating clockwise. In the WM video it is rotating counterclockwise.

Good eye Crossroads. 👍👍
I'll bet anyone a pail grits, this is the problem....

I need to give credit where credit is due.
Gmmills contacted me last night and point it out.

You can share the pail of grits with Gmmills........if you want 🤣🤣🤣🤣🤣

[Crossroads]

I don't think I've ever had grits 🤔

[Stephen1]

I don't think I've ever had grits 🤔

You are not missing much.

[Durf700]

not bad mixed in with eggs!

[PAmizerman]

I got back to the sharpener today.
It was in fact the cam direction.
I don't know how it reversed but I swapped the leads got it going the right direction and sharpened blades

[Andries]

Well done, a quick fix.

[Stephen1]

I like it when it's a simple fix! 8)