Circle mill blade heating

[bandmiller2]

Dave, you are getting an expensive but complete education on circular mills. Dark days now but you will be a better sawyer for it in the future. Hang in there mate you've got it by the short hairs.(or is it the other way around??) Frank C.

[ddcuning]

So, I sent the bearings off to D&D Sawmill Parts last week and heard from them today. Basically everything I had was crap.  >:( >:( Bad housing, new bearings were ruined, nuts were bad and the list goes on.  :'( Why in tarnation would I expect anything different?  >:( They have one of the bearing rebuilt already and after 3 hrs of running it in, it is down to 78 F in temp. Sure beats what I was coming up with that is for sure. I should have had them do the bearing rebuild the first time. Oh well, they will be good when I get them back. Don said they may be here in time for the weekend!  ;D I am going to try and not get my hopes up though.

Dave C

[Seaman]

GOOD NEWS !

[ddcuning]

Just heard from D&D Sawmill Parts and the bearings are almost complete and will ship out tomorrow. I should have them by Friday and be able to install the new shaft and bearings on Saturday. I am going to re-read through this thread and do a little more supporting below the husk and add the third bearing. Probably won't get done on Saturday but will keep at it until it is complete.

Dave C

[Jeff]

When running a third bearing, this adds another level of alignment. Make sure you have a good assortment of shim stock. You have to be dead perfect with three bearings, and you must make sure they are locked down before you do any belt tensioning.

[ddcuning]

Will do Jeff. I may not get the third bearing set on Saturday, may be the next weekend. Will just have to see how things go. I still need to set and brace posts for the third bearing so that will take some time just by itself.  I will post pics as I make progress.

Dave C

[ddcuning]

The rebuilt bearings came in this week. Spent the day at the mill today and got the rebuilt bearings on the new shaft and got the holes dug for the third bearing support. I will pour the new supports in concrete tomorrow so they will be set up well by next week and install the main sheave and third bearing next weekend. The rebuilt bearings were a little stubborn going on but ended up getting them on just fine. Took the new shaft back out with the bearings on it temporarily to make it easier digging the holes for the third bearing support. Afterwards, we enjoyed a beverage and watched the sun go down over the horizon. Nice end to a productive day.

Dave C

[ddcuning]

Today we put the third bearing posts in concrete and set the third bearing. We will let the concrete cure for a week then put the main drive sheave on, shim the third bearing and check alignment of everything.

Dave C

[Seaman]

Best of luck to ya ! It is gonna be an awesome mil.
Frank

[Jeff]

I may be completely misunderstanding your bearing set up by description, but from lots of past experience, I need to at least voice my concerns on what I THINK you mean on your bearing set up.

Your arbor bearings need to be all on the same structure. If you have bearings on different pillars or supports, or on another part of the mill that are a different component of the structure other than the husk, they will fail due to separate component movement.

We know this from very expensive experience on the last mill we had set up and it took years to find the problem at the cost of many many $700 a piece pillow block bearings and down time. It was a CMC mill. The mill was built on I-beams as one unit. It was set on concrete pillars poured on a 12" thick concrete floor.  There was a separate block of concrete, I'd say two feet thick, and 8ft square that was where the 150 hp electric motor for the headsaw sat, as well as the separate hydraulic drive system tank pumps and motor for the mill. The only other thing that sat on this huge concrete block, that sat on the same floor as the sawmill, was the outboard bearing stand for the headsaw saw arbor. There was no way that that block could ever move. Well, guess what? As it turns out, it could. Concrete will flex and move through the seasons due to changes in the moisture beneath it in the soil, be it from drying, absorption or freezing and thawing. Wood will certainly move if you are using that.

If you are using a third bearing, then you will need to have a removable bearing stand, so you can change belts on the sheave, if it is located between your outboard bearings. That stand must be part of the husk along with the other two. It can't set off on another support.  We were loosing a bearing twice a year until we figured out what was going on. Because of the set up, our solution was to add a remote temperature sensor to the bearings, so we could monitor sudden changes. Late fall and late spring were our trigger times. If I saw temp change, I would simply unbolt the bearing on the bearing stand and check for alignment. You had to loosen the belts first of course. There were times that when you unbolted the bearing, it would lift right off the support.  The other way to check bearings when using electric power is simply how long the headsaw blade takes to stop when you kill the power. That you can do multiple times a day.

I made a rudimentary drawing to try and explain what I am talking about.  I sure don't want to see you loose another bearing.


The top drawing will fail at some point.


 

We also had another separate bearing issue from day one of installation of the new mill on our hydralic motor pump drive shaft.  The electric motor drove a shaft that turned two hydraulic pumps by belt. The motor connected to the drive shaft by a boot coupling, end of shaft to end of motor shaft.  We have those $200 bearings fail once a month for the first year. We tried everything to get the alignment right, but nothing ever worked, until the last time they failed. It was something so simple stupid that came from the factory that I finally noticed. The pillow block bearings did not have a completely solid base housing. They were cast with a hollow base.  What was happening was, that the steel shimstock the factory had used to align the bearings were placed under the bearings, they were slightly shorter than the bearing housing.  When you tightened down the bearings, no matter how precise the alignment, it was flexing the entire case and putting a bind in the bearing.  The fix was shim stock a half inch longer than what the factory had used. After that fix, those bearing never gave an issue for all the rest of the years I was there.

[js2743]

Jeff, I would say you just solved the problem here, from the last post dd made he just dug a hole in the ground and then put a post for the bearing. The whole thing needs to be setting on a one piece frame to keep every thing from moving a different way.

[ddcuning]

Jeff,
My arrangement is the top that you indicate will cause bearing issues. I had considered this potential problem but did not want to extend my husk frame due to cost and having to field weld tube steel onto my existing husk. As such. I installed a 6x6x1/4 piece of tube steel horizontal on top of two 6x6 treated posts in concrete 3 ft deep. There is about 1/8" of gap between the Dodge E pillow block bearing that I selected for my third bearing and the piece of tube steel. That way I can shim between the third bearing and the tube steel and make sure that I do not induce bend on the shaft. This is about the only way I can figure on handling the issue without major modifications to my husk. I can also buy a thermal gun and monitor temps and re-adjust the shims a few times per year to keep track of the situation and keep from inducing load on the bearings.

Dave C

[Jeff]

I'm afraid, and I hate to say this, that that (tom) just is not going to work. The earth is a dynamic thing. It could move every day, it could move during the day and maybe every day no matter what the size or depth of your footings.  You need those bearings all on the same structure. You need to modify your husk. Are your original two bearing supports on a one piece husk frame?

[ddcuning]

Jeff,
Yes the two original bearings are on the original all steel husk frame.

Dave C

[Jeff]

I felt crappy about even bringing it up, and debated with myself about it after reading your post and the work you put in, but in good conscience just could not, not tell you what I know is sure to be an issue. I'm sorry about that. :-\

[ddcuning]

I appreciate your input Jeff, however, I am going to continue on the path I am on. I don't believe this issue to be such that I cannot overcome it with monitoring and adjusting. I will only be using my mill once or twice a month for a few hours at a time. I can easily put together a start up checklist and adjust the outer bearing each time before startup. If I see each time that I am experiencing alignment issues, I can revisit the problem.

Dave C

[scsmith42]

Dave, I have an engine driven welder that I can bring over if needed.

Is there a way to add bracing to the outside of your supports to lock them together? 

[ddcuning]

Scott,
I am going to brace the two 6x6 bearing supports both to the 6x6 base under the engine and to the husk. This will give me a tripod with one leg vertical and two other legs in perpendicular planes. The brace back to the engine is to aid in preventing tightening of the belts pulling the bearing in the perpendicular to the shaft and the brace to the husk to prevent pulling or pushing of the bearing axial to the shaft.

Dave C

[ddcuning]

A productive day at the mill today. I worked there 12 hrs so it got dark and I don't have pics. The third bearing tri-pod stand is in. The weight of the main sheave caused the new shaft to drop once installed. The new third bearing was only off by 25 thousands prior to the main sheave being installed and once I put the sheave on it only took one shim to get the shaft back into alignment. So new shaft and bearings are installed as well as the main sheave and belts put back on. Taking Lyle's advice I also added another support under the track right at the saw. Poured it in concrete so it will have to set before we finish backfill. Slowly but surely getting it back together.

Dave C

[ddcuning]

We got almost everything together this weekend. Still lots of little things to do though.


We also added another support right under where the saw blade is to help prevent deflections in the track from forces from the saw.


Dave C

[Alligator]

Looks good! I have put a lot of thought into your issue, not trying to solve, just considering it compared to other things I've seen over the years. It's not suppose to be that hard. These sawmills were moved, and setup on a monthly bases, without much more than a good 6' level.

Best of luck, you deserve it, as much blood sweat and I'm sure a tear or two.

[Ron Wenrich]

I've sat back and watched your progress on this third bearing installation.  I haven't been sold on the idea of needing a third bearing.  I've seen them on a few mills, and even had one that had it on.  But, those bearings were not on the outboard side of the shaft.  They were always on the husk, and added support in the middle of the shaft, so you weren't getting any flex in the shaft. 

I would have thought that the 3rd bearing would have been a lot closer to the sheave.  Seems to me you want the support to be equidistant so that its equal on both sides.  But, it should be tied to the husk.  Vibration will eventually make the third bearing ineffective.  Bracing is fine, but wood expands and contracts with weather conditions. 

As gator has said, it's not supposed to be this hard. 

[ddcuning]

The bearing on the outside of the drive sheave prevents a moment being induced on the main shaft around the bearing on the outside of the husk. The third bearing will serve to prevent this condition even though it is not tight up against the drive sheave. Since the Dodge E bearing I used is not intended as a main bearing, you would not want it that close to the husk and taking the same load as the heavier Frick bearing. Having it further away will allow the stronger Frick bearing to carry most of the load and the Dodge E simply to prevent bending moment on the shaft. The third bearing has sat there for over a week with warm day temps and cool night temps with no movement in the support members. When I checked it last Friday, it was still 0.025".

Wood expands and contracts with weather conditions...true. Steel does also. As long as I watch it closely it should not be an issue.

Dave C

[Jeff]

Ron and I were just trying to help you with what we know to be true from a whole lot of combined experience. We were production sawyers with a combined experience of well over half a century and both have done consulting for mill set up. I wish you the best. I'll not try to dissuade you any longer and wish everything goes the way you expect it to.

[ddcuning]

I understand Jeff. I am following Donald Helfrick's direction who used to work for Frick and also has years of experience setting up sawmills. He has advised me on this configuration, looked over the configuration and said that it is fine and that I will not have issues with it. Time will be the judge of that but I am proceeding under his direction.

Dave C