Thread: Bandsaw Vs Circular Swingsaw. Pros and Cons

for one's own milling use I rekon that weekend warior is worth looking at, certainly their must be a few compromises in its construction in order to keep the weight down for the single rail, and if it wasn't up to scratch it could be resold with little lost.
I would'nt mind modifying one of those to fit into a bandsaw carriage & deck

cheers,
Dean

Originally Posted by John.G

Yeah, i got out in the yard and realised I'd made an error about band kerf there Carl, and wandered back at smoko to edit. I used to work with a West Plains 500 system and that had a kerf of 2.2mm on a 5"band. Once I pay the kara off I'll be working with another one

Don't forget the 2mm of hit and miss you already quoted so kerf loss (assuming the same blade wander on band vs blade on australian hardwood - unlikely) is now 8.0mm (Lucas kerf is 6mm)vs 5.5mm. This equates to 35.0mm to 32.5mm to yield a 27mm board or approximately 7.6% greater recovery. Is the 7.6% (maximum) worth the extra time involved?

Timboz

The pros and cons of the two options are often subjective and or theoretical. My situation displays a course of events which may throw a little natural light on the subject.
We have at our disposal a vertical band mill with a capacity of 1.540m, a Lucas swing blade and a Lucas dedicated slabber. These days, the band mill only gets used for exotics of high value. All other timber goes through the Lucas mills. Why? Convenience. The ability to be used by a sole operator, maneuverability and ease of maintenance are the main reasons the Lucas gets pressed into service more often. To test my theory and to make sure I'm not missing something here, I spoke to a friend who also has a large horizontal bandsaw and a Lucas swing mill. When asked how much he uses which, he offered me the bandsaw to finance a second Lucas. When asked what about the high value stuff he said he'd get me to cut it while he kept up production on the Lucas'. He has now purchased the second Lucas and the bandsaw waits patiently for the next exotic or a prospective buyer, which ever comes first.

Originally Posted by rustynail

The pros and cons of the two options are often subjective and or theoretical. My situation displays a course of events which may throw a little natural light on the subject.
We have at our disposal a vertical band mill with a capacity of 1.540m, a Lucas swing blade and a Lucas dedicated slabber. These days, the band mill only gets used for exotics of high value. All other timber goes through the Lucas mills. Why? Convenience. The ability to be used by a sole operator, maneuverability and ease of maintenance are the main reasons the Lucas gets pressed into service more often. To test my theory and to make sure I'm not missing something here, I spoke to a friend who also has a large horizontal bandsaw and a Lucas swing mill. When asked how much he uses which, he offered me the bandsaw to finance a second Lucas. When asked what about the high value stuff he said he'd get me to cut it while he kept up production on the Lucas'. He has now purchased the second Lucas and the bandsaw waits patiently for the next exotic or a prospective buyer, which ever comes first.

RN

I can relate to that as while I had both the swingblade and the bandsaw the bandsaw hardly got a look in.

I use the bandsaw now because it is what I've got. I don't think I am about to purchase another saw. I confess at times I have thought about building a twin saw machine, but having regard to the number of projects already on the go and a lifespan of less than 100 years, I think it is unlikely I'll get around to it.

Regards
Paul

Originally Posted by timboz

Don't forget the 2mm of hit and miss you already quoted so kerf loss (assuming the same blade wander on band vs blade on australian hardwood - unlikely) is now 8.0mm (Lucas kerf is 6mm)vs 5.5mm. This equates to 35.0mm to 32.5mm to yield a 27mm board or approximately 7.6% greater recovery. Is the 7.6% (maximum) worth the extra time involved?

Timboz

Timboz

When I got out of timber milling for a living the flooring producers were just starting to ask for oversize boards. This was irrespective of the type of machine used for cutting. The reason for this was twofold I think.

One of course was to allow for shrinkage during the drying process. The second was to allow sufficient material for dressing and profiling. The third (that's very close to a couple isn't it?) was that the timber moves during the cutting process resulting in varying thickness in the same board. This is a curse of modern timber recovered from smaller trees.

I don't think the bandsaw wave was a factor. Btw a blunt circular saw can produce some horrendous cuts too.

Regards
Paul

Originally Posted by timboz

Don't forget the 2mm of hit and miss you already quoted so kerf loss (assuming the same blade wander on band vs blade on australian hardwood - unlikely) is now 8.0mm (Lucas kerf is 6mm)vs 5.5mm. This equates to 35.0mm to 32.5mm to yield a 27mm board or approximately 7.6% greater recovery. Is the 7.6% (maximum) worth the extra time involved?

Timboz

The 2mm allowance is factored into both... it's why we sit on 27mm GOS, nominal inch + 2mm.
Or 41mm for 1 1/2" and 53mm for 2".

AS 2082 allows us to go +/- 3mm in unseasoned timber and +5, -0mm in seasoned timber in terms of size tolerances. Commercially cutting most tend to ride that upper limit on GOS, because sometimes logs dont cut what you want and you get stuff that hangs back in the shed a while till an order for it comes in and by then even though it's block stacked its partially seasoned and some unit shrinkage is occuring. So that extra few mm of thickness is a form of insurance. It's easier (and cheaper) to plane any excess off one face or edge if required then it is to have to resize a board down to the next standard dimension.



Band waver is always an issue, but the wider the band the less it's an issue. Same with circle saws... step up to a thicker plate, kerf change from 1/4" to 3/8", and you'll get a whole lot more sawdust, but they will stand up in the cut without wavering. It's about getting the best balance between yield and results, and in this business 80% of perfect is where the money is. Try to get perfect, be it theoretical yield or dimension accuracy, and the increased time will eat the increased value and make less profit.

Originally Posted by John.G

The 2mm allowance is factored into both... it's why we sit on 27mm GOS, nominal inch + 2mm.
Or 41mm for 1 1/2" and 53mm for 2".

AS 2082 allows us to go +/- 3mm in unseasoned timber and +5, -0mm in seasoned timber in terms of size tolerances. Commercially cutting most tend to ride that upper limit on GOS, because sometimes logs dont cut what you want and you get stuff that hangs back in the shed a while till an order for it comes in and by then even though it's block stacked its partially seasoned and some unit shrinkage is occuring. So that extra few mm of thickness is a form of insurance. It's easier (and cheaper) to plane any excess off one face or edge if required then it is to have to resize a board down to the next standard dimension.



Band waver is always an issue, but the wider the band the less it's an issue. Same with circle saws... step up to a thicker plate, kerf change from 1/4" to 3/8", and you'll get a whole lot more sawdust, but they will stand up in the cut without wavering. It's about getting the best balance between yield and results, and in this business 80% of perfect is where the money is. Try to get perfect, be it theoretical yield or dimension accuracy, and the increased time will eat the increased value and make less profit.

Not to pick a fight John - but 2mm hit and miss was not already factored into both. Look carefully at your post where you say "27mm + 1.43mm lets say 28.5mm" The nominal thickness is 27mm but with 2mm hit and miss it will range from 25mm to 29mm. Where the band (or blade) dips it will of course leave a hollow in the log or cant which becomes the new datum surface for the next layer of boards - ie you would have to surface off 2mm to eliminate the hollows at the start of the new deck of boards (not that you would actually do it but rather just you get the mathematical calculations correct). This then means 'kerf' loss for the swing blade is 27+2+6 = 35 vs 27+2+3.5 = 32.5 for the band mill resulting in 35/32.5 = 1.076 = 7.6% extra waste vs your numbers 33.5/30.5* = 1.098= 9.8% extra waste. Which is a 9.8/7.6 = 1.29 = a 29% overstatement of the relative losses of blade vs band (assuming equal wander). *as per your acknowledgement of Carl's comment on set.

Thanks for the comments about allowances for dimensional inaccuracies, seasoning and the relevant Australian standards which are very useful for less experienced members. I am not a professional but I have cut many thousands of lineal metres of dimensional timber from many different species, log grades and sizes using a Lucas and consider myself an informed amateur. Sawmilling is, as you have alluded to, a science, an art and an enigma and I am fascinated by the different strategies, technologies and difficulties that it presents.

Regards Timboz

Originally Posted by timboz

Not to pick a fight John - but 2mm hit and miss was not already factored into both. Look carefully at your post where you say "27mm + 1.43mm lets say 28.5mm" The nominal thickness is 27mm but with 2mm hit and miss it will range from 25mm to 29mm. Where the band (or blade) dips it will of course leave a hollow in the log or cant which becomes the new datum surface for the next layer of boards - ie you would have to surface off 2mm to eliminate the hollows at the start of the new deck of boards (not that you would actually do it but rather just you get the mathematical calculations correct). This then means 'kerf' loss for the swing blade is 27+2+6 = 35 vs 27+2+3.5 = 32.5 for the band mill resulting in 35/32.5 = 1.076 = 7.6% extra waste vs your numbers 33.5/30.5* = 1.098= 9.8% extra waste. Which is a 9.8/7.6 = 1.29 = a 29% overstatement of the relative losses of blade vs band (assuming equal wander). *as per your acknowledgement of Carl's comment on set.

Thanks for the comments about allowances for dimensional inaccuracies, seasoning and the relevant Australian standards which are very useful for less experienced members. I am not a professional but I have cut many thousands of lineal metres of dimensional timber from many different species, log grades and sizes using a Lucas and consider myself an informed amateur. Sawmilling is, as you have alluded to, a science, an art and an enigma and I am fascinated by the different strategies, technologies and difficulties that it presents.

Regards Timboz

You're right mate, I haven't explained myself clearly is all.
The "real" target size here is 19mm dressed. We "average around" (rather then saying cut) 27 to allow for hit and miss... so a plank can come off at 25 or 29 and still after shrinkage and planing consistently hit 19mm DAR. If we cut 25 and got 23-27mm thick, the 23 is hard pressed to plane out. These are off cants fed to a resaw, so its like cutting with the board face vertical on a lucas. You just keep moving across the log/cant taking one plank after another and they average out.

Where you get a saving by going to a thinner kerf, be it band or circle, is in the actual cut width. If one blade is 1/8" thicker then another, then for every 9 cuts it's turned an extra 27mm into sawdust, or to put it another way the thinner blade in the same width of timber got an extra board "for free".

That's why Peterson do a "microkerf" blade for their swingmills. Haven't used it, don't personally know anyone who has... but same principal.

Peterson Circular Blades for Portable Saw Mills

Thanks for the reply John. I had to think about that one for a while before posting but I new something was left out of the calcs. I milled about 2500 lm of tallowwood decking years ago and sought the advice of Robertson bros sawmill in Gympie about G.O.S sizing for 90X19 finished decking and they advised exactly as you (and Paul) have - 105 X 27. I air dried for 18 months before Robby bros planed it up. He was pretty impressed with what I supplied as he had previously planed some pretty ordinary portable milled feedstock. My trees were very nice though (smallest d.b.h around 80cm and shortest log 4.5m).

Timboz

I

Originally Posted by Bushmiller

JG

Mahoe Sawmills Supermill 2013 - YouTube

Wow... these Mahoe mills look pretty schmick... for a Kiwi machine. Anyone have any idea of how their Supermills are priced?

Hardenfast

Back in 2000 Mahoe Supermill was about $54,000. Their Automated top-of-the-line 2000 about $100,000. Hardly entry level. I couldn't quickly find any current prices.

It's horses for courses. If I had a handy forest, a young offsider and a reliable market for the product I would seriously consider a mahoe. it's all about return on your investment.

Regards
Paul

ahhh..... twin blade mills, there lies another argument

twin blade mills are great if you have Big logs ans are going to cut 4x3 landscape posts. great in good size pine. but for the price you can get a lot more for your money.

useless for sleepers, useless on small logs, useless for long lenghs.

you cannot cut out teh tention in a board as you have to take both cuts in one pass.

as you have to make both cuts in one pass you cannot take a big cut in to goes, its not a matter of power that stops a big cut is blade deflection.

as you are taking 2 cuts and have to take each bopard in one pass there is a lot of force on teh log and as such a small log just wont stay still.

Originally Posted by weisyboy

ahhh..... twin blade mills, there lies another argument

twin blade mills are great if you have Big logs ans are going to cut 4x3 landscape posts. great in good size pine. but for the price you can get a lot more for your money.

useless for sleepers, useless on small logs, useless for long lenghs.

you cannot cut out teh tention in a board as you have to take both cuts in one pass.

as you have to make both cuts in one pass you cannot take a big cut in to goes, its not a matter of power that stops a big cut is blade deflection.

as you are taking 2 cuts and have to take each bopard in one pass there is a lot of force on teh log and as such a small log just wont stay still.

Carl

You make good points about need for large logs. In fact it is the area that I have mentioned previously is a shortcoming of all circular saws. Even my swingblade mill was not good at small logs except that I had a crude system of dogging the log to the sawbed.

The bandsaw on the other hand excells at this. In this regard it can be more suitable than a swingblade mill for people working casually and cutting small logs and this returns to the original question for Phil-nz as to what would suit him.

For example I have four small logs to cut for Forum member Berlin as shown below and these will be relatively easy to cut with the bandsaw. The biggest of the logs is about half the size of a farm strainer post.

Tulip Wood 005.jpg

Regards
Paul

I cut logs on a regular basis down to 210mm hundreds a year infact we use them for 6x6 posts never longer than 2.4m

I have cut gidee logs 100mm in diameter on the Lucas.

The beauty is you can take 10mm passes if you have to.