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Bandwheel question

Started by Danny_S, June 22, 2004, 06:27:51 PM

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Danny_S

Does the blade have to be pulled by the driven wheel? Could it be pulled around the idler bandwheel?  Like this......



 ???  ???  ???
Plasma cutting at Craig Manufacturing

Gilman

Danny, my background is in mechanical engineering.  The only time you don't drive just before your load is when you absolutely can't.  I'm pretty sure you'll have trouble with tracking if you drive your "idler".  If you do drive your idler and it works please let me know.  I'd stare at it, scratch my chin, and say, "hmmm."

Good luck
WM LT70, WM 40 Super, WM  '89 40HD
Cat throwing champion 1996, 1997, 1999. (retired)

Fla._Deadheader

  You want to "Pull" the blade through the log, not "push" it.

  In your drawing, the "pull" is on the top. ;D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

chisel

Hi Danny,

I was wondering the same thing a month ago. So I looked at pics of all the band mills I could find (plus my Delta bandsaw) and they all "pull" the blade through the wood towards the drive wheel. That's enough evidence for me.


ADfields

It would put a huge load on the idler, more then twice what it would have the other way.   This would create more stress on the band as well as the loss of efficiency and a rubber band effect that may make it hard to keep a band on the drive wheel.   A better plan would be to turn the band around and reverse the rotation of the drive wheel.
Andy

iain

you got to pull the blade through not push
if you push it will want to pile up on the out side of the log
pulling pulls the blade straight and true just think of it as a piece of chain the only way it works realy when pushing is with a stupid amount of tension

slowzuki

Danny, on the surface the answer seems obvious but when ya think about it a bit... hmmm

Think of a M113A troop carrier, don't they have the drive sprocket at the front of the track?

So heres a simple little study with some math, ignoring the elastic effects a bit:






Tension where the blade enters the log is important because it reduces the blade deflection and dive.  So the pusher has to crank up his tension for cutting.

Then you look at changes in tension when going from sawing to not sawing.  The adjuster better have some way of taking up slack as the pushed blade has a tension change over a longer length of blade meaning the length of the blade changes more than a pulled blade.

So a pushed blade may be ok with a short and stiff blade, but we know such a blade isn't very practical for other reasons.

Ken

Danny_S

Yea,.... well there ya go huh.....  I know that it is typical setup to pull the blade through.. Just was curious if it could work the other way...it was just a brainstorming idea I had for a setup.... but it would have to pull around the idler wheel.  :-/

Well, back to the drawing board for now I guess.... ;)
Plasma cutting at Craig Manufacturing

ADfields

It can work your way, you just need to account for more things to pull it off. :-/   Your buying problems so to speak, don't mean they cant be overcome. ::)   The track I don't think is a good comparison to a bandsaw, there more different then they are the alike I think.
Andy

Fla._Deadheader

  Don'T sound right about them tracks, either. IF the front sprocket is driving the tank, it will PULL from the top and all the slack will be forced under the front set of rollers. I really doubt the front sprocket is doing the driving. Dozers drive from the rear sprocket, and all the slack hangs between the top idler rollers.  ::) ::) ;D ;D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

slowzuki

FD,

I got thinking about the M113's and the rear is all people, the engine is in front and the sprocket in front.  Checked some pics, yup its in front.  It would have the same troubles as the mill like you say.

Ken

Quote Don'T sound right about them tracks, either. IF the front sprocket is driving the tank, it will PULL from the top and all the slack will be forced under the front set of rollers. I really doubt the front sprocket is doing the driving. Dozers drive from the rear sprocket, and all the slack hangs between the top idler rollers.  ::) ::) ;D ;D

Fla._Deadheader

 Thanks. Been 36 years since I was cramped up in one of them things. ::) ;D ;D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

slowzuki

[Shudder] I can't say inside one of them is where I'd like to be.

I think I'll stick to learnig how to saw ;)

Back on topic, tanks etc usually throw tracks from sideloads?  Turning on sides of hills etc?  Maybe there is a hydraulic tensionor that works all the time.  The dozers I've worked on you tensioned the tracks with a grease gun only every so often.

QuoteThanks. Been 36 years since I was cramped up in one of them things. ::) ;D ;D

Fla._Deadheader

Right again. Tanks have them things stickin up on the tracks, to help keep 'em on. Dozers have the ridged rollers to help keep 'em on. Sliding sideways will allow the slack to get the track out of alignment and you literally drive off of them.

  Ya puttin tracks on yer mill ??? ??? ::) ::) ;D :D :D :D

  Ain't NUTHIN around here we can't design. ;) ;) :D :D :D :D

  What's this thread about, anyway??? ???

  Oh yeah. Danny's buildin a tank.  ;) ;) :D :D :D :D :D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

slowzuki

Well see, we got mills we take to the trees so why not an all terrain self propelled mill.  Can be used as skidder or dozer when needed 8)

Slap a harvester head on it too ;D ;D

On the weekend use it to get to your favorite fishing spots...

Fla._Deadheader

  I LIKE it. 8) 8) :D :D
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

SwampDonkey

Fla_Deadheader:

I know they are flying the New Brunswick flag , but I thinks they's a couple newfies. ;D
"No amount of belief makes something a fact." James Randi

1 Thessalonians 5:21

2020 Polaris Ranger 570 to forward firewood, Husqvarna 555 XT Pro, Stihl FS560 clearing saw and continuously thinning my ground, on the side. Grow them trees. (((o)))

ADfields

All the track rollers on a tanks or transports today are sprung to take up the slack, witch is one of the many things that are dissimilar to a band saw.   Rollers on a dozer are solid mounted and if you ever drove a dozer all out (5 mile an hour) you know why they are sprung on fast tracked stuff! :D :D  
Andy

Danny_S

Now seriously people, how can you not take this face seriously.....


<----------------

 :D
Plasma cutting at Craig Manufacturing

Tom

I don't know...... looks a bit like a young Robert Newton.  I could picture a parrot on the shoulder and a skull 'n cross bones in the background.

Where'd you find it? :D

chet

Almost all of the industrial rubber tracked vehicles I am familiar with (go-tracs, flex-tracs, gyro-tracs, bombardiers) are driven from the front.  http://www.sotc.com/specsheets/bombi.muskplus.1.html
I am a true TREE HUGGER, if I didnt I would fall out!  chet the RETIRED arborist

scottr

Danny, Gilman , and Chisel , the Ripsaw buitl by Better Built is a bandsaw like Danny's diagram . It work fine once you learn how to properly tension the blade. Tracking has never been a problem. I just wish it had larger band wheels. It is easy to carry to the log and you can tilt the dimension plate to make lap siding . It only has a 9" X 14" throat with the 10" band wheels . Scott

Tom

Tracked vehicles were explained to me  as having a "road" laid for the wheels rather than using the track itself to pull you along.  If the track is the road then I don't guess that it matters whether it is stretched super tight or not.

I figure a  bandblade being pushed or pulled falls in the same catagory as pushing a rope, or pushing a tiger with a dish rag. :D

Gilman

Scott,
By this picture on http://www.ripsaw.com/testimonials/frederick/index.html (Better Built's website) it looks to me like the chainsaw engine is mounted on the operator's side.  Unless they are using a gear reduction, the band will be coming towards the operator just like a normal bandsaw.  I haven't used one, I'm just going by the picture.


WM LT70, WM 40 Super, WM  '89 40HD
Cat throwing champion 1996, 1997, 1999. (retired)

scottr

Gilman , the ripsaw does have a gear reduction . Mr. Graney told me that with my 044 that the band speed is about 3800 ' per min. The band is rotating to send the dust away from the operator . The weight is about 45 lbs. Scott

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