Really fun watching this all come together.
The color looks close to British Racing Green, so this will certainly make it faster
The color looks close to British Racing Green, so this will certainly make it faster
Linn Lumber 190A kit build
- Thread starter OH_Varmntr
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Maybe it would work better if you used a different color grease Bob lol.
Nice job on that, odd it isn't working well for you.
Wonder if its because of the very fine dust off your extremely hard woods.
OH_Varmntr
Burner of stored sunlight
Hi Bob, my mill utilizes roller guides with sealed bearings.
This page shows the components on the Linn Lumber mills.
https://www.linnlumber.com/partsandaccessories.html
Thanks, I hope I can keep up the pace to keep guys interested!Really fun watching this all come together.
The color looks close to British Racing Green, so this will certainly make it faster
That may not be a bad idea. Also some "bearing" greases may not cut it at those high speeds and loads. At 5000 feet per minute blade speed, a 3" diameter roller is running 6400ish RPM, a 2.5" roller at 7640ish RPM, and 2" roller at 9550ish RPM. Have you tried a high quality bearing? Different grease? Shielded bearings? I used to buy shielded bearings for another application but basically the same setup that would be submerged repeatedly in water and mud. I would pull the inner shield and drill a tiny grease purge hole in the outer shield. Helped increase the bearing life immensely.
Thanks very much for that info and it all makes sense - I will try with some sealed bearings.
I had a closer look at the Linn Lumber 1900A and 1900 models on line and realise that our mill must be an older model as it is a bit larger all round than with those mills.
Ours has a 27HP Kohler motor, a 36" max width cut , so can handle a 42" wide log. I think it has 26" wheels, and the band guide rollers are wider to supports 2" wide blades. I spoke to the boss about about an hour ago and now we know where we can get parts he's now considering rebuilding this mill.
The best thing is the boss is thinking about moving it under cover to better protect the mill - this also means I will be able to use it more often in winter which is when all our rain falls. In summer its also too hot, this summer we've had 13 days where daytime maxes have gone over 105F, and 32 days over 95F.
We are going to need a new hydraulic ram as the old one leaks, slowly - but enough to be irritating and we have lost a couple of blades because off loss of tension during a cut.
Instead of water from a hose we are going to go with a water tank with the usual dash of dishwashing liquid.
We need to do something about the guides, starting with reinserting the original rollers with new bearings but we might go to something with added support from underneath.
Two of the log bunks have major dents and need replacing.
There are couple of other rthings that need attention but I can't think of then ATM.
I will be really interesting to hear how you get on with yours and will be great to have someone with a smiler mill design to talk with about with.
Ours has a 27HP Kohler motor, a 36" max width cut , so can handle a 42" wide log. I think it has 26" wheels, and the band guide rollers are wider to supports 2" wide blades. I spoke to the boss about about an hour ago and now we know where we can get parts he's now considering rebuilding this mill.
The best thing is the boss is thinking about moving it under cover to better protect the mill - this also means I will be able to use it more often in winter which is when all our rain falls. In summer its also too hot, this summer we've had 13 days where daytime maxes have gone over 105F, and 32 days over 95F.
We are going to need a new hydraulic ram as the old one leaks, slowly - but enough to be irritating and we have lost a couple of blades because off loss of tension during a cut.
Instead of water from a hose we are going to go with a water tank with the usual dash of dishwashing liquid.
We need to do something about the guides, starting with reinserting the original rollers with new bearings but we might go to something with added support from underneath.
Two of the log bunks have major dents and need replacing.
There are couple of other rthings that need attention but I can't think of then ATM.
I will be really interesting to hear how you get on with yours and will be great to have someone with a smiler mill design to talk with about with.
OH_Varmntr
Burner of stored sunlight
Hi Bob, here is the bearing setup for my roller guides.
They don't have a very high load rating.
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They don't have a very high load rating.
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I hate to be the bearer of bad news,, but, there is a 99% chance that the very fine sawdust BobL produces is the cause of the bearing failures.
I worked for a company that built VERY high voltage (6,000 volts) and pretty high amperage distribution cabinets and we used a fiberglass type material to make brackets and supports for the copper bus bars..
The material came to us like sheets of plywood, except it was sheets of glass mat, instead of wood.
Rather than sawing, and drilling, someone saw a CNC router that was designed for wood.
It had six spindles, and ran like 20,000 rpm. They installed the machine, (this was about a $250,000 machine.)
The 1" (25mm) thick fiberglass routed beautifully,, EXCEPT,, the dust was VERY fine.
Within two weeks, all the spindles were destroyed.
The company even built a new design "air seal" that used large amounts of compressed air to try to keep the dust away from the bearings.
That failed.
It turned out that the ONLY thing that would help was slowing down the spindles.
To save the bearings in the spindles, a 50% reduction of speed was required.
We ended up having to buy a second machine,, to keep up with production demands.
Ultra fine dust is REALLY hard to keep out of bearings,,,,,,,,,,,,,,, changing the type bearing seal may not help.
I worked for a company that built VERY high voltage (6,000 volts) and pretty high amperage distribution cabinets and we used a fiberglass type material to make brackets and supports for the copper bus bars..
The material came to us like sheets of plywood, except it was sheets of glass mat, instead of wood.
Rather than sawing, and drilling, someone saw a CNC router that was designed for wood.
It had six spindles, and ran like 20,000 rpm. They installed the machine, (this was about a $250,000 machine.)
The 1" (25mm) thick fiberglass routed beautifully,, EXCEPT,, the dust was VERY fine.
Within two weeks, all the spindles were destroyed.
The company even built a new design "air seal" that used large amounts of compressed air to try to keep the dust away from the bearings.
That failed.
It turned out that the ONLY thing that would help was slowing down the spindles.
To save the bearings in the spindles, a 50% reduction of speed was required.
We ended up having to buy a second machine,, to keep up with production demands.
Ultra fine dust is REALLY hard to keep out of bearings,,,,,,,,,,,,,,, changing the type bearing seal may not help.
OH_Varmntr
Burner of stored sunlight
I work with systems from 345,000 volts AC right down to 5 volts DC and am very familiar with the insulating board you describe. Nasty stuff for sure when you cut it.
The fiberglass board is red in color,,
when the first dead spindle was returned,, the company said
"something has caused the grease to turn red!"
They had never done anything other than wood before,,
I just remembered the name,,, "GLASTIC",,
Number of years ago I rebuilt a band saw for a customer every bearing in the the unit was locked up. They were and still are cutting various types of insulation boards from fiberglass and ceramic composit materials. That stuff just eats bearings and blades.
Thanks for the info OH_Varmntr. The bearings in our mill rollers are exactly the same number as yours.
Unfortunately I can't reuse the old bearings as sealed bearings because I have removed both the seals from the inner bearings, and removed the inner seal and drilled small holes in the outer seal of the outer bearings to let the grease through.
Re: DUST Comments
Thanks for the info on the fine dust and bearings.
The thing was that when I used the grease purging method, dust in the bearings was not a problem.
The bearings still turned turned fine after cutting but the bearings and rollers got hot which is why I now suspect the grease?
FWIW while cutting we use a decent stream of cooling water both above and below the blade so there's not much fine dust floating around but theres a lot of sawdust mud.
I contacted Linn Lumber about this and within 12 hours I received a detailed reply from Chris King. I was really impressed that he replied to the operator of a 20 year old Linn Lumber kit mill. He mentioned that they supply rollers with both sealed and greased bearings but unfortunately did not provide any answers about the type of grease. He suspects the back of the back of the blade might have been too close to the back rim of the roller - he recommended an 1/8" gap - I cant remember what we used.
I have sent him a couple of more questions about setup and hopefully he will reply.
I'm going to try new sealed bearings and see what happens.
Thanks again to everyone who replied.
Unfortunately I can't reuse the old bearings as sealed bearings because I have removed both the seals from the inner bearings, and removed the inner seal and drilled small holes in the outer seal of the outer bearings to let the grease through.
Re: DUST Comments
Thanks for the info on the fine dust and bearings.
The thing was that when I used the grease purging method, dust in the bearings was not a problem.
The bearings still turned turned fine after cutting but the bearings and rollers got hot which is why I now suspect the grease?
FWIW while cutting we use a decent stream of cooling water both above and below the blade so there's not much fine dust floating around but theres a lot of sawdust mud.
I contacted Linn Lumber about this and within 12 hours I received a detailed reply from Chris King. I was really impressed that he replied to the operator of a 20 year old Linn Lumber kit mill. He mentioned that they supply rollers with both sealed and greased bearings but unfortunately did not provide any answers about the type of grease. He suspects the back of the back of the blade might have been too close to the back rim of the roller - he recommended an 1/8" gap - I cant remember what we used.
I have sent him a couple of more questions about setup and hopefully he will reply.
I'm going to try new sealed bearings and see what happens.
Thanks again to everyone who replied.
OH_Varmntr
Burner of stored sunlight
I was wondering about that also. Too much moment load caused by the back of the band riding on the roller guide wheel flange will prematurely wear bearings. Especially in this application where the bearings are quite small to begin with and are certainly not designed for such loads.
I'm looking forward to hearing results of your experiments with your mill!
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I just picked up some new sealed NSK bearings from our local (2.5 miles away) bearing store - US$14 for 4 so if they don't work out it's not going to break my bank account. It's going to be a while before I can get down to the milling yard to try them out as we're tied up for the next few days.
OH_Varmntr
Burner of stored sunlight
I was hoping to make some headway tonight but I've run into a big of a snag for now. While mocking up the bunks and laying out the log stops I noticed if placed where the print shows, the log will be clamped too far towards the axle of the fixed band wheel and will contact the band wheel and fixed roller guide.
I believe I've figured out why and have sent an e-mail requesting the location of the threaded mounting holes for the sawframe. Hopefully the resolution will only involve drilling and tapping 4 new holes and I can continue on here.
Here's a picture of what I'm referring to, I've grayed out the print out of respect for Chris and his property.
I believe I've figured out why and have sent an e-mail requesting the location of the threaded mounting holes for the sawframe. Hopefully the resolution will only involve drilling and tapping 4 new holes and I can continue on here.
Here's a picture of what I'm referring to, I've grayed out the print out of respect for Chris and his property.
Attachments
Those stops are are not really for holding logs but for thinnish billets or cants which means they can also be very small.
Those on the woodlander small mill (red arrows in picture) are only about 1/4" thick, the ones on our bigger mill are ~1/2" thick
I usually use those If I am splitting a 2" thick boar into a 1" board.
Anyway, you are correct their inner edge should be just inboard of the blade guide mechanism.
Logs and tall billets are normally help up against removable steel tube verticals as shown by in the picture - this ensures that no part of the log should come into contact with the guides.
The Woodlander has two lengths of those tube but they need to be located a bit further inboard otherwise they would come into contact with the wheel shroulds.
OH_Varmntr
Burner of stored sunlight
Hi Bob, you are correct, my use of the term log in the context of these clamps is incorrect. I haven't progressed far enough along to start installing the log stops at this time.
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OH_Varmntr
Burner of stored sunlight
Okay, so it's confirmed that I had 4 holes located incorrectly, so I've remedied that. While waiting to hear from Chris I began building the sliding clamps and got them finished last night and got a coat of paint on them today. These slide along the bunk tops and have both a sharp point for holding cants and adjustable height bars for logs.
Next I will be locating the square tubing on the bunks that will accept the adjustable height backstop bars on the fixed end of the bunks.
Next I will be locating the square tubing on the bunks that will accept the adjustable height backstop bars on the fixed end of the bunks.
I received further Information from Chris at Linn Lumber about the rollers. He said my "flow through grease" roller mod should work fine but high speed grease should be used. I found out from a machinist that the Blue grease I used would be too viscous for the bearing speeds involved and I should be using a Bentonite based (brown or tan) bearing grease.
OH_Varmntr
Burner of stored sunlight
Thats good to hear Bob! I'm not a chemist or anything, just a lowly electrician. I learned the hard way about mixing grease in motors and other expensive gear with precision bearings to know you have to use the right stuff.
This is more like it! I have a video uploading now. Should be done soon.
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OH_Varmntr
Burner of stored sunlight
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