Bouncing swing blade

[Timo]

I've had a few occurances of my blade pulling into the wood while cutting. On the vertical cut, it sets up a a bouncing in the mill carraige that leads to cut groove in the leave wood (normaly the vertical cut stops short of the bottom of the horizontal cut, and no mark is left on the leave surface).  On the Horizontal cut all I notice is that the blade tends to pull into the cut unless I hold the set lock lever in place. This is on a Peterson WPF.

Both issues seem related: in the vertical cut, the blade seems to pull into the wood until it builds up tension in the mill frame, then releases, which starts the whole frame to bouncing slightly. It does not appear dangerous, just a bit disconcerting. If I slow my cut speed way down, it doesn't happen - but then I'm crawling along. sometimes speeding the cut speed up helps, as it doesn't alow the occilation to take effect. 

This only happens on deeper cuts (over 4 inches). I thought that maybe it was caused by a tooth or two that become dull, and is grabbing rather then cutting the wood. I tried sharpening, which helped a bit but hasn't completely taken the effect away. Am I doing something wrong? Any thoughts?

I still tend to think that it is sharpness related, as it started doing this as the blade got dull - but seems to persist after sharpening.....

[Arthur]

Timo

we get the same with the EcoSaw.

Its primarily due to the type of blade in combination with the wood type.

We set the rack on blades in Aussie hardwoods to as low as 0.5mm and no more than 1.5mm.  Softwood can be as much as 3mm.  You also need to keep that blade as sharp as you can even if you need to stop halfway through and give it a fast touchup.

Most long term swingers I know end up with blades for all occassions.

arthur

[Swing_blade_Andy]

Hiya Arthur

Yes this is can be a B**********r.

I've ruined a lot good slab like this. It took me a bit of experimentation to whork out what it is.

Lubrication,  lubrication lubrication.

First make sure that your blade is sharp.. I mean razor sharp, polish both angles of the tip but don't exceed the relief angle, that'll make the tip to brittle and you'll chip in a heartbeat. Then you behind where you were.

Then, presuming that your blade has good tension and is not bending, you need to make sure your intermediate strut is locked to prevent a sine wave building up in the rail.

Then and here's the last and best bit, make sure you literally pouring water down that cut, if your in a very fibrous wood, spruce (I refuse to cut it now) or well what ever, add just a dash of diesel or detergent to the mix. But I found this mostly a feature of very hardwoods: oak ewe, wot not.

I'd be interested to know if its worse for you on new blades or blades you’ve retipped, because the side relief angle is really important and will make a very bad cut if your not true and free.

Also make sure you always cut at full revs and ease the cut in before you accelerate down the straight, hopefully you'll not meet a chicane in the middle.

Cheers
Andrew

[woodbeard]

Timo, you mention the blade pulling into a horizontal cut unless you hold the handwheel. The handwheel periodically needs to be adjusted. I'm not sure if the newer models are the same, but on mine, it's just a matter of two 19mm wrenches- there is an acorn nut ( or maybe it is the head of the bolt? ) on the front of the wheel and a nylock nut on the opposite end of the shaft ( bolt? ) that goes thru the wheel. With the lever in the free position, adjust these so that the lever starts to lock the carriage about an inch before the full locked position. The back nut needs to be tight against the aluminum, or the shaft will turn with the lever. It takes a bit of screwing around with before you get the hang of it, but you will get it.
If this has changed since the 1998 models, hopefully Captain, or someone from Peterson will have an update.

[Timo]

Thanks for the help! That's what's great about this Forum, I typed a question in at 10:30 last night, and this morning at 6:30 had 3 answers on the subject

Went out this morning, cleaned the pitch off my blade, upped the water flow, tightened up the set lock, and cut 300 board feet of nice fir beams in just over an hour

thanks again, I think I've got the 'problem' figured out now....

Cheers,

[woodbeard]

COOL!
It's a great feeling, aint it?

[Captain]

Woodbeard hit the response on the head with the horizontal cut pull,  I had 2 miscuts in the Shootout due to that adjustment 

Vertical cut...do you have a large frame mill??

Captain

[Timo]

Yes - Large frame mill, I'm compensating 

Sure builds up a rightouse bounce when the pitch builds up and the grain starts to waver...... I guess it's that wide expanse of Aluminum flexing.  More weight/ metal would hold it in place, but I don't think I could push it around then!

Some thoughts on the larger frame: While you might not need it for every log (or many), and it does add weight, it sure is nice to have the extra space to walk next to the log.

[Arthur]

Having triangular rails on the EcoSaw tends to eliminate the bounch but we find that when we extend past 8m the rails start to rotate on the pivots.  This give the same effect of bounch.

The original square rails just bounced either way.

However, to strengthen the rail they have increased weight by 40%.  Bit of give and take which everway you go.  If you want lightweight extreamly portable you need to know how to control and eliminate the bounce.

Ive even seen the bandsaw equivelant of bounce where the whole unit ossolates in the direction opposite the band direction.  This happens in particular with some of the aussie hardwoods.

Swing_blade_Andy try some cheap cloths washing powder.  The cheap stuff works well with fury woods.

arthur

[Swing_blade_Andy]

Thanks arthur

But I'm retired from cuttin'

Jest talk about it now.

Never did like sitka spruce though...

Andrew

[woodbowl]

Andy,
   Tell me what you don't like about Sitka Spruce. If I find myself in the US NW, I hope to saw myself a supply to bring back home. I am getting ready to build another ultralight aircraft soon and I will have to buy it from Wicks this time. When I took A&P we used a lot of white pine for construction, but it is not as good as Sitka Spruce.-------Does it saw fuzzy, slow or is it simular to another type of wood that I may be familar with?  Thanks

[Off_bear_err]

I am getting ready to build another ultralight aircraft soon

Well lets hear and see about the first on, eh?

[woodbowl]

Sounds like you and Buzz may want a Plane project in the future. I'm just hoping to find some Sitka to saw, if not I'll have to settle for white Pine.

[Timo]

Swing_blade_Andy, 

Thats interesting news. I haven't had the opportunity to mill any spruce yet, but I would have expected it to cut up nice. It is a prefered construction wood here, at least interior (Engelman and Sitka) Spruce is. It takes a nail well, rips up nice, and doesn't finish to bad, turns out a bit like pine actually. What have you found when milling it that makes it difficult?

Just curious....

[Furby]

I want to hear about (and see) it as well woodbowl!

[Kirk_Allen]

Hey Arthur,

what did you guys do to get the bounce out of the eco-saw you had at the shoot out.  Seemed like it wouldnt take much more than a 4" board to get that thing rocking pretty good.

Just curious what fixed it as if I recall correctly that unit was a prototype.

[woodbowl]

Furby,
   Are you talking about Andy telling us why he doesn't like Sitka or me talking about U.L.aircraft?

[Buzz-sawyer]

My kid was quoting ya wood bowl....trying to get ya to talk and post pics about your ultra light...now I am too...so is furby.Man your popular

[Arthur]

what did you guys do to get the bounce out of the eco-saw you had at the shoot out. Seemed like it wouldnt take much more than a 4" board to get that thing rocking pretty good.

Just curious what fixed it as if I recall correctly that unit was a prototype.

Kirk

The 35hp has heap more weight then the normal 18hp.  To prevent the endframes from causing bounce (normally 2"x1") they made it from 3"x1.5".  This beefed up the endframe but the pivot points for the rails where actually 20mm to low on the bottom rail making the mill sit on the lower instead of hanging from the top.  This caused all sorts of problems.  The biggest was the blade guards which although modified for the new 21" blade not all mods had been done correctly.  There arnt many who understand the maths behind the mill.  Lindsay has had an extreamly high learning curve this year and I must admit he almost knows as much about the mill as I do know.  The blueprint gets stuck in your head after a while.

The blade was another problem as it was taken directly from the D&L Doublecut quatersaw which has no problem with bounce due to its weight.  Our cradle is only 1/4 the weight so the blade needed to be redesigned for ours.

Lindsay has these blades in stock now and has made the some new jigs so the 35hp now cuts like a dream.  If you ask him he should have a CD video of it available now as well.  Its right on the edge of what I define as portable but is an amazing mill.

Im sure Lindsay will keep everyone upto date with everything.

arthur

[woodbowl]

OK Buzz, Furby,  I'll have to dig out some pics. Takes me a while. I should probably start a new thread. This one is getting a little side tracked.--- Not much to tell really. I like to fly UL's, soloed when I was 17, I'm 49 now, worked with Weedhopper flying airshows in 79, built a foam composite Gold wing (canard) had several tube and fabric over the years. Just commited the aviation sin................I sold my only flyer before I got another airworthy. Now I am grounded untill I fix something else. Got the construction plans to build a himax and Minimax. (wood & fabric) This is what I would like to have the Sitka Spruce for. Close grain, quater sawn white pine is good also. I'll settle for that if I have to. ...........Maybe someone out there has access to some close, straight grain, free of knots, sawen paralell with the grain, white pine or Sitka? Sometimes I run up on some tight grain yellow heart pine. The type used in flooring. Maybe we can cross paths somewhere and swap for what we need.

[Swing_blade_Andy]

Timo
Seeings how you asked.

'Why I hate sawing Spruce'
By Swing blade Andy.

Most of the Spruce trees I got to saw were edge trees. Shelter trees, very low grade logs indeed.

There was a never ending list of problems.

1. The value of the timber was so low that I couldn't justify my cutting charge to the client unless he wanted beams than then it was touch and go. HE could buy the timber form the hardware at about 130- euro per cubic meter. Which is for nothing.

2. Most of the trees I was given to cut were from fence lines and so were full of wire, nails, bottles, bullets, steel bolts and all sorts of this stuff not good for the saw.

3. When you do get a log under the saw the resin is very sticky and there is lots of it needing a flood of water to prevent the blade gumming up and then heating up...... destruction of a blade.

4. Even if none of the above occurs and you’ve got a half decent log under the saw the knots a so hard that the rest of the wood so soft so that you can race along and 'bang' you hit a knot. Sometimes its enough of a shock to loose a tooth, than the following tooth hits the loose tooth and your changing blades (again).

5. The texture of the timber features very long fibrous grain, which is great for many building applications. But it never seems to cut clean; some of the fibres tear and so leave a fur. This is sometimes enough to increase friction and therefore heat in the blade. If it heats up enough then it buckles and 'whammo' your blade tension is gone. Change blade again and its back to the saw doctor for re-tensioning. But its never the same.

I gave up. Anyone who had spruce trees of anything like them I recommended cutting them with the chainsaw for the fire. I sold only Douglas for construction... None of the above problems. Lovely.

The end.

Andrew

[Captain]

Nice story Andy.

I would have liked it better if it started with "Once upon a time...."

Captain ... (who also has experienced the above when sawing spruce, remember the biggun at SAWLEX folks??)