Is my B-20 carriage twisted?

SRM · April 25, 2020, 11:07:09 AM

Had a slight problem when moving the mill. I did not lock the carriage in and it hit when I put on the breaks...result is that it saws okay, but the blade is not parallel with the frame cross member.
I had to replace chains, wheel belts, and aligned it the best I could. It seems to cut well, but not like I remember.
Is this a problem that will get worse? Can it be fixed? Any help would be great. br>

doc henderson · April 25, 2020, 11:19:13 AM

sorry to hear SRM. when you say hit, did the gantry tip over? when you say you had to replace chains, do you mean the travel chains (did they break). is it twisted or just off a cog on the sprocket. You might call the TK guys to see if this has happened before (I am sure it has) and see what they recommend. I doubt it will get worse. is the blade parallel in the horizontal plane meaning above the deck? do you see a bend in the gantry framework?

SRM · April 25, 2020, 11:32:03 AM

Quote from: doc henderson on April 25, 2020, 11:19:13 AM
sorry to hear SRM. when you say hit, did the gantry tip over? when you say you had to replace chains, do you mean the travel chains (did they break). is it twisted or just off a cog on the sprocket. You might call the TK guys to see if this has happened before (I am sure it has) and see what they recommend. I doubt it will get worse. is the blade parallel in the horizontal plane meaning above the deck? do you see a bend in the gantry framework?

It slid forward when I abruptly stopped and it slammed against something along the deck. Nothing broke at the time. A few choice words were said and a plea sain for nothing to have been destroyed. I haven't noticed any welds or anything broken. I don't know how the four post frame is attached to the rails. Maybe something can be loosened and moved back into place?

Tom the Sawyer · April 25, 2020, 12:03:33 PM

If the retainers were too loose on the carriage (the four L-shaped brackets that hold the carriage to the rails, the head frame can lift. Make sure that the all of the rollers are making full contact with the rails. You may have to shift the frame side to side to get them to reseat. Measure from the frame scrapers to the end stops on each side to make sure it is even. When the head moves forward unexpectedly, the first contact point would normally be the drive side guide roller bracket hitting the first log stop. If the stops were down then it might have hit the folded loading arm. Don't ask how I know that.

SRM · April 25, 2020, 12:10:28 PM

Quote from: Tom the Sawyer on April 25, 2020, 12:03:33 PM
If the retainers were too loose on the carriage (the four L-shaped brackets that hold the carriage to the rails, the head frame can lift. Make sure that the all of the rollers are making full contact with the rails. You may have to shift the frame side to side to get them to reseat. Measure from the frame scrapers to the end stops on each side to make sure it is even. When the head moves forward unexpectedly, the first contact point would normally be the drive side guide roller bracket hitting the first log stop. If the stops were down then it might have hit the folded loading arm. Don't ask how I know that.

Thanks,Tom. I'm glad you know of someone else that this has happened too. :D I did measure from the frame scrapers to the end stops on each side and they are off about 1 inch. Do I loosen the L shape brackets to shift the frame side to side or are there other connection points that I also need to loosen?

KenMac · April 25, 2020, 04:44:47 PM

This may or may not be pertinent to your situation, but yesterday I noticed that my Cook's AC 36 had one drive chain looser than the other and the stops were 1/2 inch different when measured to the frame. I checked it out this morning and found that the back side chain was 1 link off when compared to the front chain. Simple fix-----just loosen adjuster bolts and slip chain back into place. The mill is as smooth as new now. I have no idea when or how they got out of alignment, but it had to be a hard lick or a fast stop somehow.

crowhill · April 25, 2020, 05:34:31 PM

My B-20 was running like that by just a little bit when I got it. It had one link difference on the drive sprockets. Adjusted the chain to be equal links on both sides and adjusted the bolts on each end of the chain, that made it much better. Over time it got cockeyed again. I installed new chains, adjusted it true about six years ago but now it's starting to go cockeyed again. It doesn't seem to have a big difference in the way it cuts, but bugs me.

Tom the Sawyer · April 25, 2020, 07:18:09 PM

SRM,

If your carriage is off by an inch, I would remove the nut from the chain bolt that goes through the bracket on the side that is farther from the operator's station. Move the chain one link over the drive gear, pull the saw frame closer to that side which should take up the slack in the chain, and put the bolt back through the bracket and put the nut back on. Ideally, your locknut would be in about the middle of the bolt threads. It is close to running out of threads, you might want to jump two links. It is a good idea to chalk the chain and the cog it is on, that way you can tell that you have jumped one link. It is handy if you drop the chain, it is close quarters when moving the chain over the drive wheel.
The L brackets are only a concern if the rail rollers jumped the rail. If not, don't worry about that until you get the head square with the rails. When you do adjust the L brackets, between the bottom of the rail and the nylon pad, there should only be enough clearance to insert a business card. I added internal tooth lock washers on mine to keep the adjustments secure.

doc henderson · April 25, 2020, 09:16:24 PM

If you did an alignment, are the two wheels in the same plane. if the blade tracks well, I assume they are. if it twisted the gantry frame to put the left side of the blade ahead of the right side (as you stand at the controls behind the gantry) then I do not think it would keep a blade on it. I have the 2000, so check in with @Tom the Sawyer . the travel chains (drive) on mine have some adjustment, and it looks to be off by a link. on mine the two sides are linked via a 3/4 inch shaft with cogs on each end, and set screws that hole them in place. might see if the forces spun a cog a bit. does it seem to be in a bind when it travels? good luck. thinking out loud here.

edit add: I wrote this in am, and just posted. I see that Tom has chimed in on his own! good luck.

farmfromkansas · April 25, 2020, 11:34:00 PM

When I left my MP32 outside, the chains got rusty, and even with oiling, they would have a link that did not swivel, and that would cause it to jump a link. Replaced the chains and keep it in the shed now when not sawing.

ladylake · April 26, 2020, 03:54:07 AM

Yes just loosen the chain on one side and move it a cog or 2. Having it off doesn't affect sawing at all. Check the bolts that mount the head to the frame, they can break. Steve

SRM · April 26, 2020, 05:43:51 AM

Thanks to everyone with your help. I went back to the mill yesterday and noticed the idle side chain was pretty loose and tightened the adjusting bolt... not much changed, it is just too loose.
After reading the comments this morning, I will remove the bolt and move the chain up one or two links. Maybe I'll just buy a new length of chain for both sides. Anyone know the length of the chain? I believe it is a #40 chain, but don't know the length. I would rather not take it off until I get a new one to replace it. I have to keep sawing between rain drops, (Pignut Hickory, and Oak) I do leave it outside, but want to build a pole barn for it this year. I need to start looking at some plans soon. Thanks again for all your comments and help.

ladylake · April 26, 2020, 07:45:42 AM

If you decide to replace a 100' roll should be more than enough, I've had a roll here for a few years but am still running the original chains after 15000 hours. Over the years I've had to take out around 10 links on each side as the chain stretches.. My mill never gets in a shed, just oil the chains . Steve

luap · April 26, 2020, 08:40:54 AM

Typical practice on replacing a chain on any piece of equipment is to count the links, not measure the chain. Condition of the sprockets should be looked at closely. New chain on worn sprockets will present problems. If you have removed several links prior you need to look at getting slack adjustment back to original and make sure sprockets are not worn. Good bet they will be if you have removed links. This is just a maintenance observation and not related to your specific application.

doc henderson · April 26, 2020, 08:48:47 AM

I bet if you call TK, they can share with you the length/number of links of chain you need. Matt is always helpful and the techs are great.

ladylake · April 26, 2020, 10:51:21 AM

Quote from: luap on April 26, 2020, 08:40:54 AM
Typical practice on replacing a chain on any piece of equipment is to count the links, not measure the chain. Condition of the sprockets should be looked at closely. New chain on worn sprockets will present problems. If you have removed several links prior you need to look at getting slack adjustment back to original and make sure sprockets are not worn. Good bet they will be if you have removed links. This is just a maintenance observation and not related to your specific application.

So long as the head goes back and forth I'm going to run the original chain and sprockets. I've taken links out a couple at a time as I was out of adjustment to keep the chains tight. When I replace I'm not counting around a 1000 links, I'll measure with a tape measure, leave it a little long then take out what needed after it's on the mill. Steve

pine · April 26, 2020, 12:03:45 PM

Just did a chain replacement on my TK . Move the head to either end of the mill so that you have a known fixed position relative to some position reference the frame. Mark the old chains on both sides at the drive sprocket (I used the 12 o'clock position) and then you only have to count links for a very short distance. Makes it VERY easy to re-tension the new chain so the head is square and the chain links are the same so that the head STAYS square with use.

redbeard · April 26, 2020, 12:35:54 PM

Curious if saw head touches evenly on the rail stops when chains are removed front and back.
If it doesn't and saw head appears tweaked then call TK you may need too relax the saw head and re plumb.
It's a procedure that's not in manual.
It will take a hour on phone with them too walk you through it.
Wear marks on your rails will also tell you if your saw head is crabbing usually it's the idle side bed rail outside corner of rail will have less wear.
Hope this helps TK tech support is awesome and they will have the right answers.

ladylake · April 26, 2020, 01:14:10 PM

These enough play in the carriage rollers for the head to twist a little if the drive links get a cog or 2 off. The chains keep the head square with the frame when they're adjusted right. Steve

ladylake · April 26, 2020, 01:19:08 PM

Quote from: pine on April 26, 2020, 12:03:45 PM
Just did a chain replacement on my TK . Move the head to either end of the mill so that you have a known fixed position relative to some position reference the frame. Mark the old chains on both sides at the drive sprocket (I used the 12 o'clock position) and then you only have to count links for a very short distance. Makes it VERY easy to re-tension the new chain so the head is square and the chain links are the same so that the head STAYS square with use.

I think Luap was talking bout counting out the links on the whole chain, I'd never make it up to a 1000 or so without goof up if I did have the patience. Steve