Can a twin blade cut fwd and rev

[CaseyK]

Im new at all of his & im sure this is a dumb question but since i saw it on you tube i thought i would ask.

Im building a twin blade sawmill (one horizontal and one vertical intersecting at the same point in the log with the horizontal blade leading the vertical by 4-5") and as i approach the log i will be cutting on the left side of the log.

My horizontal blade will be rotating counter clockwise (from a top view) so it will enter the rear of the log and exit out the left side, my vertical blade will be rotating clock wise (if you were on the right side of the log looking at the blade), the blade will enter the top of the log and exit out the rear of the log. 21" horizontal and 26" vertical peterson type blades.

While researching twin blade sawmills on the internet i saw a you tube video of a guy running a twin blade and he would cut a board with every forward pass then adjust (x,y) position of the blade intersection then cut a board while making a reverse pass. He was manually pushing the mill by hand and it had a 1200cc engine on it.

If i cut in reverse my horizontal blade would enter the log from the side and exit out the front and the vertical blade would enter the front of the log and exit out the top.

In the past i know that the big circular saws were hammered or tensioned to cut left hand or right hand which meant a lot and was from what i understand to be an art so that the blade would cut true and i assume that these were meant to cut primarily in one direction.

So my question is if there is anyone out there that has a twin blade that has tried cutting a board while doing a reverse movement and what was the results.

[Swatson]

I was was wondering if you could do that as well.  If it does then you could get a board off with each pass which is pretty sweet.

[backwoods sawyer]

As i approach the log i will be cutting on the left side of the log.
My horizontal blade will be rotating counter clockwise (from a top view) so it will enter the rear of the log and exit out the left side, my vertical blade will be rotating clock wise (if you were on the right side of the log looking at the blade), the blade will enter the top of the log and exit out the rear of the log. 21" horizontal and 26" vertical peterson type blades.

  

  

 

On this home built over sized mighty might both the main saw (42") and edger saw (32") ran counter clockwise.
It can cut in both ways just not the way you are thinking ;) When shaving the log to change angle to get the best CVG recovery you could shave in both directions, but all sawing was done in just one direction.

Not sure how reversing the eger saws direction will effect sawing :-\

[Ron Wenrich]

I believe reversing the edger saw will throw material back towards the sawyer. 

I think it would be more advantageous to have a dragback, instead of trying to cut another board.  Having loose material around moving saws isn't all that safe.

[Ianab]

Issue with the blade rotating the "wrong" way is that you are Climb cutting going into the log. This tends to drag the saw into the log faster and the blade tries to ride up over the wood. I know if you get mixed up and try a reverse vertical cut with a swing blade, bad things happen.

As you would need to stop the saw head anyway to safely remove the sawn board I can't see how it would improve production. By the time you have removed the sawn board the saw carriage could have returned, dragging the sawn board off at the same time. Whether you are sawing alone, of have an off bearer standing beside you at the front of the log, this is going to be faster than man handling the board off the side.

[CaseyK]

Thanks Fellas

I thought i would just ask since i saw the guy on you tube doing it, it looked like it worked good for him.

My mill will have a board drag back system for forward motion and reverse motion if it can cut accurately in reverse.
And the feedworks rate will be very slow while researching this option & designing a full proof board drag back system which will probably only be reliable when flat or plain sawing boards & not when quarter sawing.

My saw carriage (left and right) mounted to the frame (up & down) is mounted to the 4 post main frame with 1" acme rods with uhmw slide plates against the 4 uprights, all of this weighing probably close to 1500 lds should help keep the blade from trying to ride up but that is definitely a concern.

Thanks again for your inputs, i appreciate all of them.

[Ron Wenrich]

I worked with a crew that used a Mighty Mite.  They produced quite a bit of quartersawn lumber.  If you do it right, you'll pull it off of all 4 sides.  You won't have to split logs to get the quartersawn lumber.  Just separate as you go.

[backwoods sawyer]

Take a look at the drag back system on the mighty Might. The pair of rollers under the edger saw are part of the end frame. Behind the main saw is a spring loaded flapper. I have drug back 12x18x 32' beams onto the outfeed tables, but they put a strain on things (it will cut 40' beams)

If you are looking to automate everything you need to consider how you are going to handle the wood. The Mighty Might had a Scissor lift roller table that would raise with the saw that was a big labor saver. The scissor lift along with a roll case and transfer chains allowed us to build units right off the mill.

Another thing to keep in mind is when these saws through chuncks of wood they will fly. I have had a chunck the size of a sticker clear the 10' wall at the far end of the mill and land on the other side of the county road. 

Note both saws direct the chips to the left side of the mill where there is a tall wall at the base is a chanel with s drag chain. May be something to consider where you will not be sawing them and leaving them.



 

[CaseyK]

Thanks Backwoods Sawer, I remember seeing that on a Mighty Mite video once and that would definitely be the best way to go and a lot more simpler than what I was considering. 

Thanks

[double cut1]

my double cut has a follower blade that keeps the lumber stress from pushing on the blade . it will not cut backwards. the return is slow but very strong for bringing back 4*6 18' long .

[tjhammer]

casey theirs a u-tube of a home built twin blade saw mill cutting both ways its called( home made twin blade saw mill in action) I guess if your saw is heavy enough you can cut both ways he is doing it with no problem
tj

[CaseyK]

Thanks TJ
That's where I got the idea from. My mills probably weights around 1200 lbs so I think she will be heavy enough for it. Once I got my mill cutting manually I tried cutting on the return 2 times and it performed just as good as going forward but once I get back in March and get all of the automatic positioning stuff installed im planning on doing a lot more testing to see if it affects accuracy or causes any additional problems but if nothing else it can be used to take the last bark cut all  the way to the left while returning that alone will save me 2 trips down the log and time is money.

[Southside]

Casey,

I watched the same video you are talking about, it does appear it works well, can't say why.  The poster had replied to a number of his comments, maybe ask him if that has created any problems or what he did with his blades??

[tjhammer]

casey I read your post  don't remember if you had or going to use inserted teeth,what I am wondering how would the inserted teeth act on the return cut does it make any difference on inserted teeth.
tj

[CaseyK]

Hi TJ,
Im not using inserted tooth but will probably get a set of inserted tooth blades this summer. Im looking forward to running some test and seeing how the mill responds. If nothing else it will be nice to use it for doing bark cuts on the return. The reason I looked into it was that I am going to hopefully eventually have a completely automatic setworks that will control the positioning of the (x,y) cutting axis of the 2 blades and if cutting on the return stroke is possible then atleast some of the time it should increase production a lot. Im at work for another 3 1/2 weeks but hope to let you know how it works mid march.