Bands saw blade diving on knots and wider parts in the same log

[BobL]

Well, on the 13th Nov the boss placed an order for a Woodland HM130 and apparently it arrived yesterday - so all up 10 days.
Given that it was 2600 miles away in Brisbane (on the other side of the country) and a lack of transport vehicles and drivers, plus all the border restrictions between States due to Covid etc I'd say that's pretty good. I'm itching to get down to the yard (29 miles away) to start assembling it but have babysitting today so it will have to be tomorrow.

 

[BobL]

Started the assembly process this morning and it took us about 3 hours just to unpack the boxes and assemble the bed/rails. Looks nicely made.
I had to leave the boss reading the manual at around 1pm as I had to go off and do other things
Will take some photos next time.

 

[BobL]

Mill is finally assembled and this morning we made the first cut.


All working good so far with nice straight cuts .

 

[BobL]

Spent yesterday morning setting up the water lube system and cutting up some small Silky Oak logs with the new mill.
The first cuts were like butter but the sapwood was riddled with termites and loaded up with sand and muck which knocked the hell out of the blade.
Had to stop cutting after the third log as it was barely cutting.
Apart from that its very nice to use, not too noisy and the water helps keep the dust down a bit
Picking up some new bands this morning and then I will be getting the blunt blade onto the sharpener.

Silky oak is notorious for allergies and I lightly scraped my forearm while carrying a slab and it came up as a red welt. I hope it hasn't overly sensitised me to this wood as it can get so bad you cannot even touch it.

 

[BobL]

Back on the big BS mill yesterday.
Cutting flats along the tops of logs for playground pieces.

The first two are of a Spotted gum. As you can see these logs are badly twisted so wouldn't make decent lumber anyway.
The mill was nearly maxed out in terms of cutting height. The throat is 36" but the max height of the band above the bed is 30"
If I have to make cuts any higher than this I'll hav etc get out the CSMs.




The one below one is a Tuart, a very rare type of eucalypt no longer available in commercial qualities. It's a very hard wood and contains lots of tannins as can be see with the two black stripes across the log were I briefly stopped to add wedges. Water is used to cool/lube the band and the tannins in the wood reacted with the water and steel band to turn the wood black. Milling with a CSM builds up a hard black resin on the chain so diesel is sprayed on the chain to reduce this effect.

It's probably too good for a playground piece but that's what we're being paid for.

 

[BobL]

Just when I thought I had the old BSM sort of sorted ,the Dipping and Rising in the cut is back with vengeance.
Last week while the boss was placing a big log on the mill with the truck crane (HIAB) when the log bumped the mill rail frame and one end of the rails came off the concrete base. I was really pleased it was not me that did it as I would not have heard the end of it.

Anyway major exercise in fixing it as the mill had to be lifted off the the rails.

Rails lifted back onto concrete pad and re-levelled - this can take an hour or so but it only took about 15 minutes this time.
At this point two of of the wheels on the mill that run on the rails were found to be sloppy and we thought it might have been the bearings but it turned out they had 12mm diameter bolts through the 1/2" (12.54mm) bearing bores. So of to a bolt supplier to replace the bolts. But the new bolts wouldn't fit through the old bushes either side of the bearing so go home to bore these out on the lathe.

Then check all the mill geometry and back to Dipping and Rising. Tried out all the usual things, new blade, higher tension, more water, moved the gullets closer to the tyres, etc.

The boss is under pressure to get his lumber contract completed so I suggested we consider breaking up the big logs (there are not that many) with a chainsaw mill so they can fit on the smaller BSM. Given the amount of time we have spent messing around with the old BSM we would have done this by now

It's been really hot here, 4 consecutive days where its been over 105F and one day it reached 110F with a couple of days either side of 100F. I take medication that increases my possibility of getting heat stroke so I have been starting at around 7am and finishing up around noon (I am supposed to be retired!) and the going home and sitting/sleeping in air-conditioning.

As I was wrapping things up for the day I saw the boss dragging out his 880 with the 48" bar. Then he realised he did not have a chain so he was off to get one. I've offered use of one of my CSM (which are all at home) but he says he needs to get his sorted anyway as he has a log that is too big even for the big BSM to handle and wants to be independent of my gear.

 

[Woodchuckr]

Bob I hope you can get it sorted out. Bearings or blocks for blade guides?
What WW stand for?
Not sure this info on tensioning is relevant, but I've never heard of this method :
http://www.suffolkmachinery.com/six-rules-of-sawing.html

They make great blades, lower tension than others run. Used them for years.

 

[Woodchuckr]

Just when I thought I had the old BSM sort of sorted ,the Dipping and Rising in the cut is back with vengeance.
Last week while the boss was placing a big log on the mill with the truck crane (HIAB) when the log bumped the mill rail frame and one end of the rails came off the concrete base. I was really pleased it was not me that did it as I would not have heard the end of it.

Anyway major exercise in fixing it as the mill had to be lifted off the the rails.
View attachment 952964
Rails lifted back onto concrete pad and re-levelled - this can take an hour or so but it only took about 15 minutes this time.
At this point two of of the wheels on the mill that run on the rails were found to be sloppy and we thought it might have been the bearings but it turned out they had 12mm diameter bolts through the 1/2" (12.54mm) bearing bores. So of to a bolt supplier to replace the bolts. But the new bolts wouldn't fit through the old bushes either side of the bearing so go home to bore these out on the lathe.

Then check all the mill geometry and back to Dipping and Rising. Tried out all the usual things, new blade, higher tension, more water, moved the gullets closer to the tyres, etc.

The boss is under pressure to get his lumber contract completed so I suggested we consider breaking up the big logs (there are not that many) with a chainsaw mill so they can fit on the smaller BSM. Given the amount of time we have spent messing around with the old BSM we would have done this by now

It's been really hot here, 4 consecutive days where its been over 105F and one day it reached 110F with a couple of days either side of 100F. I take medication that increases my possibility of getting heat stroke so I have been starting at around 7am and finishing up around noon (I am supposed to be retired!) and the going home and sitting/sleeping in air-conditioning.

As I was wrapping things up for the day I saw the boss dragging out his 880 with the 48" bar. Then he realised he did not have a chain so he was off to get one. I've offered use of one of my CSM (which are all at home) but he says he needs to get his sorted anyway as he has a log that is too big even for the big BSM to handle and wants to be independent of my gear.

You would be surprised how much tension you lose when blades heat up, Even with coolant. Wide boards and a wrong blade/dull blade and the problem just gets worse as you progress through a cut. Your wood guides probably make more unwanted heat. Myself I would get some good guides on it first and get it all aligned properly.

These are good guides I put them on my first BS. If you pause the video at 1:27 you can see the adjustable scraper in front of the bearings to eliminate the buildup you were getting. https://timberwolfbandmillblades.com/proddetail.php?prod=TWGS03

When the BS cut straight at first was it on narrower cuts / smaller diameter logs?

 

[BobL]

Thanks Woodchuckr I really do appreciate the input - even its just bouncing around ideas.

You would be surprised how much tension you lose when blades heat up, Even with coolant. Wide boards and a wrong blade/dull blade and the problem just gets worse as you progress through a cut. Your wood guides probably make more unwanted heat. Myself I would get some good guides on it first and get it all aligned properly.

I agree - If I forget to turn the water on the tension drops off rapidly by 25% or more, and if its a green log steam can be seen coming off the end. The drop in tension is not surprising as I worked out the band will lengthen by about quarter of an inch per 100F rise in temperature. If steam is coming off the ned it must be over 212F so the band will have lengthened by about 1/2".

This mill has an hydraulic ram to tension the blade with a pressure gauge so I can clearly see what the tension is. I usually set the tension at 20,000psi and then warm up the engine (no cutting) and the tension drops off to 15,000 over about 20-30s seconds so I re-tension it back to 20-22,000 PSI. During a cut the tension drops off maybe about 1-2000 psi but I adjust that about mid cut and it holds true after that. I have tried cutting with the tension ranging from about 18000 to 26000 psi - no difference.

I run enough cooling water so there's no steam coming from the blade - band can easily be touched as soon as I stop. I will check the band temp tomorrow with my IR thermometer and will do that tomorrow,

These are good guides I put them on my first BS. If you pause the video at 1:27 you can see the adjustable scraper in front of the bearings to eliminate the buildup you were getting. https://timberwolfbandmillblades.com/proddetail.php?prod=TWGS03

Yes they do look good. I note it says "Note: The system must be blown out with compressed air after every 30 minutes of use." , well I certainly wasn't doing that on the old rollers.

I'm going to try and put the big roller guides back onto the mill. The mill came will wooden guides but the vendor told us that he had rollers somewhere . I was lucky to get the rollers because the seller didn't know where and took some time to find them.

I will try to convince the boss to spring from some new guides.

When the BS cut straight at first was it on narrower cuts / smaller diameter logs?

When we first got the mill it had wooden guide blocks and it cut straight (wide or narrow logs) for about two years - then it started cutting crooked - I tried a zillion things and eventually it started cutting straight again. - I tried some narrow(12") cuts last week and it was not too bad but after the mill rail was moved it wouldn't even cut the narrow stuff straight.

Oh one more thing. Sharpening generates a small burr on the gullet. Is this likely to affect performance? I don't think is does because brand new blades with no burr behave just the same.

Thanks again.

 

[Woodchuckr]

Thanks Woodchuckr I really do appreciate the input - even its just bouncing around ideas.

I agree - If I forget to turn the water on the tension drops off rapidly by 25% or more, and if its a green log steam can be seen coming off the end. The drop in tension is not surprising as I worked out the band will lengthen by about quarter of an inch per 100F rise in temperature. If steam is coming off the ned it must be over 212F so the band will have lengthened by about 1/2".

This mill has an hydraulic ram to tension the blade with a pressure gauge so I can clearly see what the tension is. I usually set the tension at 20,000psi and then warm up the engine (no cutting) and the tension drops off to 15,000 over about 20-30s seconds so I re-tension it back to 20-22,000 PSI. During a cut the tension drops off maybe about 1-2000 psi but I adjust that about mid cut and it holds true after that. I have tried cutting with the tension ranging from about 18000 to 26000 psi - no difference.

I run enough cooling water so there's no steam coming from the blade - band can easily be touched as soon as I stop. I will check the band temp tomorrow with my IR thermometer and will do that tomorrow,

Yes they do look good. I note it says "Note: The system must be blown out with compressed air after every 30 minutes of use." , well I certainly wasn't doing that on the old rollers.

I'm going to try and put the big roller guides back onto the mill. The mill came will wooden guides but the vendor told us that he had rollers somewhere . I was lucky to get the rollers because the seller didn't know where and took some time to find them.

I will try to convince the boss to spring from some new guides.


When we first got the mill it had wooden guide blocks and it cut straight (wide or narrow logs) for about two years - then it started cutting crooked - I tried a zillion things and eventually it started cutting straight again. - I tried some narrow(12") cuts last week and it was not too bad but after the mill rail was moved it wouldn't even cut the narrow stuff straight.

Oh one more thing. Sharpening generates a small burr on the gullet. Is this likely to affect performance? I don't think is does because brand new blades with no burr behave just the same.

Thanks again.

I don't think the burr affects anything, with the tooth set it probably doesn't touch the wood you are cutting just hits the sawdust.
If you are absolutely sure the blade is correct for what you are cutting I would
Get a hold of the saw manufacturer and check it is all aligned to spec and ask what they think. If they are lined up proper and the right blade for the wood type and size is used it should cut pretty darn straight. Too high Blade tension or lack of tension from manufactures specs may pull your saw alignment out. When I first went to Sulfolk for their blades they advised me to tension the blades to their specs and then re check my saw alignment as they require much less tension than other blades which may throw your saw out of alignment. It sounds like you may have two things at play throwing you around. I am no expert but to me it sounds like maybe not quite the right blade and something out of alignment, and they amplify each other? Hope you get it figured out.

 

[BobL]

I don't think the burr affects anything, with the tooth set it probably doesn't touch the wood you are cutting just hits the sawdust.

That's what I was thinking.

If you are absolutely sure the blade is correct for what you are cutting I would
Get a hold of the saw manufacturer and check it is all aligned to spec and ask what they think.

Unfortunately there is no manufacturer. The Mill was purchased as a Used mill about 7 years ago from a miller who bought the pieces from different manufacturers in the US about 15 years earlier.

If they are lined up proper and the right blade for the wood type and size is used it should cut pretty darn straight. Too high Blade tension or lack of tension from manufactures specs may pull your saw alignment out. When I first went to Sulfolk for their blades they advised me to tension the blades to their specs and then re check my saw alignment as they require much less tension than other blades which may throw your saw out of alignment. It sounds like you may have two things at play throwing you around. I am no expert but to me it sounds like maybe not quite the right blade and something out of alignment, and they amplify each other? Hope you get it figured out.

Although some parts of the mill are not as rigid as I would like, the basic frame of the mill is built like a brick outhouse. I set all the angles with the band at 10,000 psi and then recheck it at 20,000 and there are no changes all the angles.
Thanks for the suggestions.

 

[BobL]

Today I swapped back to the old tyres on teh old BSM - these are wide and thicker so this meant repositioning the guide blocks and redoing tracking and general geometry - it all takes way longer than I like.

I also removed the burr on the inside side of the gullet ,of the same band I was using last week, using an angle grinder with a well used flap sanding wheel - slow but it worked well.

So, same blade - different tyres and burr removed.
Tried it on a 16" diameter, 8ft long hardwood log and . . . . . .
Guess what - No diving! - just a long shallow rising cut in the cut! about 1/2" by the end of the cut.
The follower wheel guide block had been providing within about 1/2" of the gullets so I added a 3/8" spacer behind the guide block so support was now within 1/8" of the gullet.
Now the band dipped and rose about +/- 1/4" along the cut.
ARRRGH!

The boss though it might be enough to break up big logs so I loaded this Brutus onto the mill.
It's an Iron bark about 40% harder than hickory.
The bark is thick and resinous and picks up loads of grit - genuine blade blunting material

I made one cut - same rising and dipping (mainly rising again) , blade started struggling - will need to peel the bark off along the cut and try again with a new blade tomorrow..

Meanwhile the boss (Jeff) and his daughter were churning out lumber on the Little Woodland.
I haven't been to the milling site for a few days but on New years day and yesterday Jeff was using his 880 chainsaw mill to turn logs into cants with.

Today they had that woodland working to maximum cutting capacity - this is Lemon Scented Gum - its also very hard

Here's Amanda doing her bit - she cut all the slabs on the sawhorses.

 

[BobL]

This morning I looked carefully at the band I used yesterday and notices the left and right teeth sets were (a) "not much" (<20"')and (b) "not the same" - outside was ~ 5"' more than inside - this was weird because it was a new blade with maybe 2 dozen cuts on it.
Now it could be that something else being out on the mill caused this and maybe why the dipping and rising has being so erratic.
So I took a look at the other blades and in terms of set they were all similar.
Then I looked at the setter and sure enough it was also wrong!

So took a freshly sharpened blade, rejigged the setter and carefully set all the teeth to 26"'
Whamo - straight cuts at last!
The red Iron bark is really hard so I poured on the water.
I'm also using a reduced hook angle otherwise they band goes blunt much quicker.

The wood is very nice (although the log has a pukey centre)
The wood is going to be used for park benches - shame really because it will all go grey in the hot Aussie sun.


I easily squared up yesterdays wonky cut and made 3 squared cuts so it can go on the small mill.
Cuts were all quite good. The Boss is VERY happy as he now doesn't need to use the CSM.

I spent the rest of the morning resetting a bunch of blades.
I kinda kick myself for not checking this closely sooner.

Thanks to all who helped.