I'm fixin to start troubleshooting a Gang Saw, tomorrow.
First problem is, feed rolls are slipping. I know how to solve that.
Second problem is, saws get hot and burn blue spots. I THINK I know why, but, solving this problem is more complex. There are NO splitters behind each blade. Should there be, to prevent pinching, shoving blades around ?? Any other ideas concerning hot blades ???
The Mandrel is supported by 2 bearings, spaced about 20" apart, enclosed in a tube, with the blade section hung out unsupported ??? Why not Pillow Blocks ??? The bearings are greased with gun grease from the center of the tube ??? Must take 5 tubes to fill it the first time, and I don't think that will help the bearings run cool ??? They get mighty DanG hot after 5 minutes of running.
This is a custom built machine. I see better ways to build these.
Pictures would be very helpful ;) Was this unit homebuilt with whatever was available to meet a local need?
Your mandrel isn't getting that hot that it makes the blades blue, is it? My bearings get hot on my vertical edger, and that doesn't seem to get into the blade.
What type of blades? If they are inserted teeth, how are the teeth? If they get too narrow, you might have something rubbing the blade.
How many hp are you running? Rule of thumb is 5 hp/blade/inch of wood. If you don't have enough power, you can heat up the blades. Then there's also belt slippage.
12" blades, carbide tipped. 4 on the shaft at this time. Set up to cut 3" wide slices from½" flitches. They are using it as an edger set up right now, and stress is in all the outside flitches. They stack 4-6 flitches together and rip the stack ::) ??? Blades and machine are new. I believe that is the WORST thing to do with the machine. Wait until we do the level and plumb, and try cants. ::) ::) Wadda I know ::) ::)
25HP 3 phase electric motor. Belts are new and tight. Maybe just a tad too tight. Shaft is not heating the blades. I think it's stress in the wood. Doesn't take much to pinch or shove blades sideways. That's why I asked about splitters behind each blade. It's tight but doable, if needed ???
Worst thing, it's propped up on boards on the wet ground. Told them 2 days ago to get the concrete slab cured, move the machine, and we will level, plumb and sight in all adjustments. They couldn't wait to play. Now, blades are blue.
There is some build-up on the blades. That will cause scrubbing and heat. I questioned water misting the blades, but, the guy says there is another machine that cuts all day long and no water, so, he doesn't need any ::) ::)
It's tough getting ideas across. ::)
Harold...I thought you were the Boss in that operation.... ::) ::) not so??
This is a local Sawmill. He has helped me a little and I'm trying to return the favor. 8)
Harold,
Some of that stuff you have down there is like steel. WHat kind of wood is it?
I know the Peterson would get mighty hot when the blades got pinched. I think you may be on the right track. My table saw will do the same thing.
It's softer hardwood. Laurel it's called. Spanish Cedar, also. I'll try to remember photos tomorrow. ::) ::)
You might be on the right trac with the thinking of a splitter. I know on my edger it is running 2 blades with a 27 hp Kohler and I have had some hickory and the likes that will have enough stress in it that it will stall the engine on the edger and I am just cutting one board at a time 4/4 thick. The other thing to look at would be the man feeding the saw is how many boards is he feeding at a time. I know from my hired help that they will try to push things to the limit and beyond. ;D
I've never seen a splitter on any edger. The old Fricks used to put a piece of angle on the table behind the stationary blade. But, the movable blades have nothing like that.
Our Edminston has a saw guide on the movable saw. That's just to help the saw move on the mandrel.
I'm thinking maybe your saws are a little crooked as compared to your infeed table. In other words, you might be running your board into your saw. I had that problem on a double end trimmer. We put a little lead on it, and it worked great. Is there an adjustment on the mandrel bearing?
You might also be having a problem with stacked up flitches. Its not quite the same as a single board. You could be getting "chatter" between the flitches as they go through the saw.
Are you getting heat when you run a single or a full sized board?
After getting the thing leveled and plumb, lead was the first thing I wanted to check. This is a shop built machine , one off. MIGHT be enough slack in the bolt holes to get some lead. Don't know, yet ??
Sometimes it runs boards through just fine. Other times, we HAD to manually pull the flitches through, all the while smoking up the joint. ::) ::) ::) ::) ::) ::) Brute force is always best down here ::) ::) ::)
I KNOW it needs weight on the outfeed roller. Probably on the infeed also, but, how would one shove a 3" thick cant into the infeed rollers ???
When the operator shoved boards at the infeed, he never tried to "help" guide them. Just stuff and watch ::) ::)
Single boards are ½" thick. They had TRIED to run some oval shaped flitches through. Got partway, and I guess pulled them back out ??? ??? I wasn't there.
Got the operator to REVERSE the flitch and it fed right through. It DID have stress, and the outside parts would warp under the center part. I showed the owner the "Steps" of the part binding and the saw cutting more into the outside edging, and he just shrugged ??? I'm giving him a half day and see where we go from there.
Thanks for all responses. 8) ;D
For the infeed side, just put a heavy roll on a slide. Then, use something to raise it up when putting the flitch through. We have a hydraulic cylinder, but you could rig up either a foot control, something like the retractor lever on those of Frick manual mills. Or, have an overhead where you pull down. You're pretty smart. Should be able to figure it out.
Do you have kickback fingers? Might want to consider them if you don't.
I have a cornell edger with one fixed blade and two that move on the left side of the machine. On the right side of the machine I have 4 set blades used as a gang. My edger is 42" wide all blades are carbide 16"Dia. I have no splitters on the machine the carbide teeth are wider than the thickness of the blade. I have fed three 1/2" boards through the gang at a time without ever having any problems. So it's my guess that something is out of whack on that edger plus now they have probably cooked the blades making it harder to figure out whats wrong. If a little pushing didn't work a lot of pushing and forcing and swearing ain't gonna work either. I learned that the hard way ::)
Lots of kickback fingers, Ron. 8)
The front press roll, is actually 2 rollers, hinged in the center of the two. It lets the cant "Walk" under the first roller, then it raises the second, IF everything is kosher ??? 3" is a LOT to stuff under rollers ::) ::)
I'm knowledgable about Edgers. Had a Corley on my Circle Mill set up. This is a true gang saw. They HOPE to get up to 10 slices at a time with this thing ??? ::) ::)
We will see. ;D :D
Lots of prep work before we shoot the juice to 'er, manana. ;) :D :D
Just out of curiosity what is the blade shaft diameter. I wonder if your shaft is cantilevering without an outboard bearing. This would cause more lead on the outside blade versus the inside blade. Many of the older roll feed gang saws use a blade shaft over 3.5 inches in diameter to counteract the shaft wanting to cantilever.
That was one of my concerns. Shaft is 1¼" I believe. There is 16" hanging outside the bearing ???
The shaft on my cornell is at least 3"or more. The guy I bought the saw from would slab a log then push the 6" thick cants through this edger to make 6x6. I think there trying to cut to much with that edger and the shaft may be flexing making the blades wander.
Quote from: Fla._Deadheader on October 25, 2007, 05:52:24 AM
That was one of my concerns. Shaft is 1¼" I believe. There is 16" hanging outside the bearing ???
Hope there's nobody standing downstream WHEN that shaft breaks :o
I agree with all who think the shaft needs more support- like a bearing at both ends ::)
Now how ya gonna convince that guy? He already knows everything ???
The mereen johnson gang saws use a quick release triangular plate with an outboard bearing. Mattison moulders use a huge casting with an internal collet to expand shafts tight into the outboard bearing. Many gang saws use a saw sleeve that allows quick removal of the saw cluster. Sleeves allow quick setup changes as well as beefing up the internal shaft. Raimann saws use an expanding hollow shaft (keyed) which is hydraulically pressurized to tighten saw sleeves to the shaft. This allows very rapid width changes on the shaft without removing blades. There are some good pictures on exfactory.com if you need some design ideas.
The edgers I've seen used shafts the size of mill mandrels. I believe you might have a flex problem. Not to mention that you are pulling on that shaft with your really tight belts.
Self centering bearings?
The shaft measures in MM, so, lets say it's 2". Blades are close to the bearing housing, and spaced with ½" spacers, so, shaft flex is possible but negligible.
Had to shim the infeed rollers on one side. Got the frame pretty close, considering the slab is good enough ::) ::)
Belts are running crooked by ¾ of a groove on the main shaft belts. About 30" between centers of pulleys, so, that creates heat and will eat the belts. Right angle gearbox for infeed-outfeed rollers is out about ¾ of a groove from lining up, and that belt is already trashed.
There are NO slots on motors-gearboxes- frames, to allow for lining things up.
Also, when you feed a cant, after it clears the second set of infeed rolls, the cant will "Dip" from saw pressure cutting the last 12" of the cant, so you could end up with a mouthful of wood, if you don't pay attention. That HAS to be remedied. No problem with that one.
Last time we tried a cant, had 7 blades cutting 3" thick cant at one time, for 8'. Can't remember the formula for HP per tooth ??? Using 29 HP 3 phase. I don't think he has enough to run all 12 blades like he wants.
Mostly cutting Laurel and Cedro. That's about equivalent to white cedar in physical characteristics. Maybe just a bit more dense.
Seems to do a pretty fair job, so, I feel we can get it cranking out material like it's supposed to.
Appreciate all the responses. ;) :)
If it's really happening.....'member we need pics.... ;D ;D ;D
F.D.
Are the blades clammed-in so they don't turn on the shaft? Is the set-up putting side pressure on the bearings so that they over heat?
I think that that 1 1/4 shaft will break at the bearing with all that over hang! There is no way it will take all that strain.
Seven blades
X
3" per blade
X
5hp
........... Hmmmmmmmmmmmmm
All you need is 105 hp and you are good to go, go , go!
12 blades?
(clicketty zip zip zing - computing noise)
180 horsepower on a 4" shaft and here we go again.
I'm thinkin of reducing the feed speed. These cants zip right along, when they feed correctly.
Lots of playing tomorrow. ;D ;D
Builder from the Big City, didn't show today >:( >:( >:( Manana >:( >:(
Mill owner isn't happy. >:( >:( Told the guy, tomorrow be here, or I'm not paying the balance due, due to machine not working. 8) 8)
Ennyhoo. Here's photos (BT). ::) :D :D
First 2 are the business part of the gangsaw.
Second 2 are the Bandmill cutting logs. You can see the guy in the white shirt. He rides the carriage and advances-retracts the headblocks.
The logs are FULL of dirt from dragging. No one cleans the dirt off ::) ::) ::)
I had a talk with the owner, and he talked to the workers, and they pretty much ignored him ::) ::) Problem is, most are family >:(
He wants to increase production by speeding up machines. I asked why the gangsaw was not in line with the outfeed of the cants ??? He didn't know ???
I asked why one person was not assigned as yardbird. Clean logs, clean debris, help turn logs or stack cants. Many other things to clear up tying up of the experienced ?? helpers ?? He didn't know ??
He agreed that production would be greater, but, I doubt he will make the changes. ::) ::)
(https://forestryforum.com/gallery/albums/userpics/10330/gang1.jpg)
(https://forestryforum.com/gallery/albums/userpics/10330/gang2.jpg)
(https://forestryforum.com/gallery/albums/userpics/10330/gang3.jpg)
(https://forestryforum.com/gallery/albums/userpics/10330/gang4.jpg)
Is the housing/frame of that so called gang-saw strong enough to prevent the saws from getting out when the arbor shaft breaks? Its going to break but when?
Send us a picture of what happens when it breaks.
Would it not be better if they had a bearing supporting end of the shaft?
I'm wondering if somebody hasn't put this thing back togather and left off a piece or two.
that big nut on the end of the shaft has a round extension on it, probably to fit in a pillow block bearing bolted to the frame below it. I agree, send pics when it explodes.
Cantelivered arbors have been around for at least 25 years. Pendu Mfg has been using them in gang saws that will flat out produce a bunch of lumber. Here's a video where you can see some of their setup.
http://www.youtube.com/watch?v=P133fTPmcms
You're not going to get away with a 25 hp motor on these. Heck, we have a 50 hp on our horizontal edger and a 60 hp on our vertical. Not enough power and too much feed can be a real problem.
As for production, making equipment go faster is not the answer, unless you have someone that is a really good mechanic. Too much speed will bust things apart. There are lots of better ways to increase production without increasing equipment speed. Sounds like he needs a mill study done.