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How much beam sag is acceptable?

Started by KiwiBro, January 17, 2015, 09:34:03 PM

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beenthere

Impressive machine, and design. And well within any tolerance for even finished board or dimension lumber grading rules, let alone rough sawn.
Thinking you are being held up at the pass for an upgrade without additional cost, but that is just a take on the flow of this thread.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

Dave Shepard

A friend of mine went to a World's Fair in the '60's and someone had a 1' piece of high rail set up between two blocks. You could push down on it with your finger and get a reading on a very sensitive indicator. Millionths of an inch, or maybe even smaller, but the point is, everything deflects. To say that a beam could be built that would not deflect is erroneous. I don't think a couple of mm is going to be an issue. You better hope for the most well behaved logs ever sawn to think that you will have lumber without any deviation.
Wood-Mizer LT40HDD51-WR Wireless, Kubota L48, Honda Rincon 650, TJ208 G-S, and a 60"LogRite!

Ga Mtn Man

Clearly Turbosaw and Kiwibro have different ideas of what is "acceptable".  Why not just take the mill back and give him a full refund and be done with it?
"If the women don't find you handsome they should at least find you handy." - Red Green


2012 LT40HDG29 with "Superized" hydraulics,  2 LogRite cant hooks, home-built log arch.

Joe Hillmann

Quote from: KiwiBro on January 26, 2015, 09:13:13 PM
With the 1.4m beam extension sold with the mill:

http://youtu.be/EwkMilpn0Zs


Again, turbo have advised they have no problem with this on their beams and such sag is perfectly acceptable. So, I'm asking again, do you guys think that is acceptable?

If I want to spend time and money I don't have getting this back to them, they will crown it.


Have you run cut any logs with it yet?  That would be the place to start.  Measuring the lumber is more important than measuring the beam.

RayMO

The old saying "make a mountain out of a mole hill" comes to mind  8)
Father & Son Logging and sawing operation .

longtime lurker

Quote from: NZJake on January 27, 2015, 04:27:33 AM
For those that think there should be zero sag in a beam or 'elevated track' sawmill could prove to me as a fact 'that other manufacturers have zero sag with an unsupported 6m span I will give Kiwibro a heavy duty beam. Place the carriage at the centre of the unsupported span and measure the deflection. I'd like this verified too. I've been from show to show and have compared other mills rails/beams and I know what I've seen first hand.

Now I'm being told that the beam is actually too light. Well yes it is light (designed to be carried).



Jake I've always said you're one of the more innovative sawmill designers out there, and I get what you're saying. Particularly given that the warrior mill is designed to be ultra portable, making things heavy is self defeating. There was a time in my life when I've had given a testicle to have something like what you're now building in terms of weight for those "carry it in on your shoulder" jobs.

Sadly a lot of people dont get that every sawmill - regardless of whether you spend $5000 or $500,000 - is a series of compromises, and that for a machine thats designed to be portable one of the design issues is going to be weight vs stifness. It's impossible to build a mill that weighs little but has the stiffness of a fixed mill.

I've seen a beam saw that had zero sag - it weighed close on 5 ton. But I'm not going to verify that because it would be comparing apples with oranges.

Kudos to you for being prepared to back your product to that degree.



The quickest way to make a million dollars with a sawmill is to start with two million.

Holmes

  The proof is in the pudding, old saying. Cut some wood and see the results.  My guess is the lumber will be fine.
Think like a farmer.

Nomad

     I still say that 10mm sag (one figure mentioned) is too much droop.  However, 2.5mm (another figure mentioned) wouldn't be a problem in my view.  Sounds to me like NZJake is being more than reasonable trying to make things right.
Buying a hammer doesn't make you a carpenter
WoodMizer LT50HDD51-WR
Lucas DSM23-19

Woodbilly

I have the c/s warrior. I am happy with it, suits my needs. The sag in my 5m beam measured mid span is 5-6mm with carriage 3mm without. Acceptable, just. I have been watching Jakes progress with the 4/stroke version and my concern was the wieght of the whole engine setup, not really portable, engine setup weighs alot, so why mate it with a limp beam?.  If kiwibro had concerns about beam stiffness pre sale and Jake knew the beam was on the light side, why send it out?. Why not insist on going heavier as the beams are now. Would have made for a happier customer. I think if Jake really cared about his customers he would meet the cost of returning the beam to be crowned or sort the Kiwibro out with a heavier beam at a reasonable price. Wouldnt even consider using the slabber attachment with that much sag in the beam it would translate to the slab, timber might be ok. Wonder what Mahoes acceptable beam sag is?. Jakes a clever dude no doubt, but i think he could do better listening to the end user.

NZJake

Hi Guys,

Thanks for variety of views. I just want let you know that the light weight beam does have options. we offer the beam split kit as an option with your purchase. It includes 3 insert tubes and the bolts.

What this allows you to do is crown your beam to the degree of your satisfaction. We put a crown in the steel inserts which then bolts to your beam. Same goes for the extension part.

So my suggestion maybe that I send out Kiwibro these inserts with pre set crown in them. If he's not keen on sending the beam back he can cut the centre of his beam and drill a few holes to accomodate the join.

Solves a couple of things. Beam breaks down lighter. Suddenly he can crown the beam to his hearts delight.

Does that sound like a reasonable offer?

Going to the heavier beam... If his beam is brought back to the factory we will exchange it for the bigger steel beam. Will offer it to him at a very low cost.
Wife says I woke up one morning half asleep uttering thin kerf and high production, I think I need a hobby other than milling?

ladylake


How many of our beams or lumber turn out perfect due to stress with any mill? Say you get 2 sides perfect at 6" then while taking the other 2 side off it will bend the 6" way. Once in a while lumber behaves good, most time not.  Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

KiwiBro

There is an unwarranted and incorrect inference being made that my posts are some sort of twisted negotiation for a cheap steel beam.

It hardly deserves a response but let me clear up any misunderstanding. I do not and have never wanted a steel beam from Turbo.

What I have always needed is a 4-stroke, portable mill I could set up over logs by myself and be proud of the lumber I can produce with it, and the service I can provide. The weight of the ali beam is at my absolute maximum safe personal carrying capacity over rough terrain like paddocks and back yards, etc. Anything heavier would not be my kind of 'portable'.


Further, to address some of Jake's points; just like the earlier statement of fact that I was advised of these levels of beam sag, I cannot ignore, and must dispute, the assertion the mill was sold to me as "transitional" or anything other than rock solid, warranted, and fit for purpose. Amongst the reasons given for the great deal I was being offered, which in case it was ever in dispute I acknowledged in my earlier video posted here, were that he had just got a big export order so had economies of scale and that I had been waiting a while for them to bring to market a 4-stroke option, so he was looking after me. At no stage was I ever told this was some sort of experimental, hail-mary, suck it and see product, rather one born from their vast sawmill experience and design skill. In fact, I was told the beam had been beefed up from their chainsaw powerhead options and was solid. I'll leave viewers of the videos I have posted to decide if that beam is their idea of solid.

I made a mistake of not insisting the mill was set up so I could inspect upon collecting it. I should have, in hindsight, insisted rather than assumed that would be the case, and I should not have deferred so easily to what I believed at the time was a strong enough foundation of experience and competency within Turbo to absolutely ensure the mill would not fail to meet my expectations of what I feel I was lead to believe I was buying. If this beam was experimental, I consider it unreasonable to withhold such information.

All along with this beam saga, Jake has said there is no fault so no warranty claim. That the levels of sag are acceptable. All along, it is clear we differ in that regard, hence why I'm asking others what they think. I can tell you absolutely no manufacturer that I have approached recently has advised of such levels of sag in their mills. One was in the ball park to the sag of this 5.6m beam, but using longer beams and much bigger engines. Another has nothing like such sag when using way longer spans and way heavier engines. Granted, it's hearsay and I have no idea if they'd sign affidavits to back up what they are telling me.



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golddredger

Kiwi,
At this point what is the problem here? Jake has offered just in this thread alone several times that he will gladly crown your beam and even get you inserts for it to add more crown to whatever you like. How can that be beat? He is offering you the fix 100% free. You have to drive to his shop drop the beam and coome back and pick it up done? Yes it is going to cost you a little time and some petrol but he has offered to solve the problem. If it where me here in Ca. And his shop was only 2 1/2 hours away I would have already made the trip and been back to cutting lumber. My first post was on your side and This is to much sag for me. But it has been addressed by Turbo mills and numerous guys here. At this point what are you looking to acheive? Yes it is starting to look a bit strange to all of us. I can see why it is starting to come accross as you are trying to push for something we are just not sure what? Load up the beam and go get it crowned or better yet modified so it can take the inserts and you can set the beam up for what you want. Problem solved. Now you can get to work and make some lumber to be proud of. Good luck in your milling adventures.
Home built bandsaw mill and trailer for a mini logging operation. Lots of chainsaws and love the woods.

KiwiBro

The issue of deflection is itself a symptom of beam softness. Will the softness br splved so that the bounce problems will be solved or will I simply get back a crowned but soft beam that still has the bounce problems? I will get up a video of the bounce. Most people will be shocked. Further, take a good look at the beam profile. Forces acting in one plane translate into the other plane. When bouncing in horizontal cut, it is also bouncing vertically putting even more load on the blade.

Did you watch the second video where o said its about 8 hrs driving to get this back? I note Jake has trouble accepting that too, asserting its way less. If he had thought to ask instead of dismissing my words so easily and inserting for his brand of the truth he would have been told I'm on location in middle of nowhere near Kaitaia in far north.

But I guess people still prefer to believe Jake and dismiss what I say. They probably still think this beam sag translates to 3mm in the cut. I have spent tpo such time today doing another video that shows that with the 5.6m beam with 1.4m extension on, there is approx 18mm sag and 12mm horizontal bow in beam that creates 14mm or so and 10mm or so in the cut, respectively.

I cannot see how crowning the beam can fix all this, solve the bounce, and generally make such a soft beam behave, but certainly remain open to being convinced it will but you'll have to excuse me if I need more than blind faith that it will solve these problems, when blind faith contributed to the mess I  am in.
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NZJake

Hi Kiwibro,

Sorry didn't realise you were on some remote job.

You'll find many videos of the mill being used without bounce. You'll need to use the anti-bounce device if you are experiencing this. Certainly one could make the mill bounce if so desired - just pull it hard enough and you'll get it. We do have a roller kit for this however (just as other manufacturers do), I have already offered this to you.

Its obvious that I haven't been able to explain the reality of the sag your mentioning. So I've attached a drawing taken from my program showing true sag which you would experience in the log. After you take away the ends where the saw pivots. You might notice with other saws that the end extension components are loosely fitted and have there own sag situation going on - that's because this support area at the ends really are not that important.

The beam's standard length you will get 3mm sag as I've pointed out.

In the extended beam you will currently experience around 9mm of sag in the timber (that's assuming that your getting 18mm due to actual sag, rather than a loose fitted extension). So understandably adding say 7mm crown over that full length will certainly bring the beam into an acceptable personal tolerance which you have stated earlier (2-3mm).

The side bow. You'll note the beam width is 150mm instead of the 200mm, so it has a little more tendency to extrude a certain way. I'm pretty sure we can get that to your tolerance too (if you can provide me your expected tolerance while being realistic). I expect a lot of that will just be a matter of being a little more fussy assembling the extension joiner together.

Also note that by splitting your current beam and adding the steel inserted joins you will actually gain strength too. That's one of the options I suggested earlier.

I note that you are suggesting that the beam is soft. Fortunately I have done many FEA's on the beam before it was extruded and does not come any where near its elasticity limit. That's to the point of stretch that it can not recover.

Sorry for bothering everyone. Just figured I needed to respond. I'm signing out now...

Hopefully this attachment helps...
Wife says I woke up one morning half asleep uttering thin kerf and high production, I think I need a hobby other than milling?

NZJake

Kiwibro, noting your comments regarding the beam being too heavy carting it across a paddock. It seems to be an impossible task to offer any scenario that will satisfy your special set of requirements.

Although I will not accept any money back scenario (you've had the mill for some months now) I do recommend bringing the saw back to us where we will be happy to on sell it for you. I have a number of customers that would snap it up in a flash. I can not see it lasting a couple of weeks at the price you bought it.

I'd actually like a first hand look at what your noticing too.
Wife says I woke up one morning half asleep uttering thin kerf and high production, I think I need a hobby other than milling?

dgdrls

Quote from: NZJake on January 31, 2015, 07:28:24 AM
Kiwibro, noting your comments regarding the beam being too heavy carting it across a paddock. It seems to be an impossible task to offer any scenario that will satisfy your special set of requirements.

Although I will not accept any money back scenario (you've had the mill for some months now) I do recommend bringing the saw back to us where we will be happy to on sell it for you. I have a number of customers that would snap it up in a flash. I can not see it lasting a couple of weeks at the price you bought it.

I'd actually like a first hand look at what your noticing too.

I have read this thread with great interest,
 
Kiwi,  I sympathize with you.  You had an expectation and it was not met.
I do not profess to know your situation or your expectations in a mill, however,
fact remains, it can only be so light and still meet a certain spec. of weight V. transportability as you have learned.

IMHO NZJ has made numerous reasonable offers to resolve this issue.
The last being to sell the mill for you,  NZJ would still be the point of sale and any issues
that may arise later will be in his court not yours with a potentially unhappy buyer calling,
I'm certain there are some associated cost for both of you to absorb here
but to continue belaboring the point is not a productive solution.

Best
DGDrls





pine

I too have been following this thread with interest as not only do I think the reader can learn about a newer device that looks absolutely fascinating in its capability but also it is very instructive in how a thread can be allowed to develop and the reader can have their initial impressions be modified as the topic develops.
I know next to nothing about hybrid swing blade mill designs and mills that are truly portable versus the term we often use for portability with our WM, TK Baker, Cooks and others.  While I do think that the Warrior mill would still be a bit of a stretch to pack in on your back it is still very portable to some out of the way sites. I can see something like that having a big market in places like Alaska where rivers and air are often the only way in.

When the thread started I was completely on the side of KiwiBro in that the amount of sag he was seeing "seemed" to be excessive.  While I still tend to believe that it is excessive, when I see how the mill operates, the design and functionality seem  to counter that a good bit.  As was pointed out there are always tradeoffs.  You cannot have light weight, true portability and not have a higher degree of flex in a beam. For the design and weight of the beam that looks pretty good.  With the techniques that Jake seems to have/offer to counter the natural beam sag I would think that it would be quite acceptable.  Having followed and spent the time to look at all the videos (thanks Jake for the 27:05 video link that was great, just wish you had finished all the way to the bottom of the log. I was interested in how the last couple of cuts would go, Oh Well)
I would not hesitate to look at the product if I needed a mill such as the one that is demoed and discussed here. 

Kiwibro
You may have been an uninformed buyer as you did not do enough research or talk to enough other end users of the product to understand the limitations of the design.   Maybe the seller, Jake if he was actually the sales guy, did not push hard enough to make certain that you understood the limitations of a mill that is designed to be that portable and light but it is not the sales guys prime job to accomplish the buyers due diligence on a purchase. That job falls to the buyer.
From the postings that have been made here it appears that Jake has made nearly every reasonable effort to satisfy your issue with a solution.  I am not saying that his solutions are going to resolve the problems but you have not availed yourself of the possibility of a solution.  You just keep saying the same thing over and over.  I understand you are not happy, I might not be either but you have not allowed Jake's attempts to resolve your problem come to fruition. 
Yes it is a good distance drive to have to drag the device back to him.  I would not be happy either to make the drive.  Unless he agrees to drive and meet you half-way or something you are getting no where at the moment.  You are not happy with the mill but you have done nothing to help Jake resolve it with you.  You have, or so it seems, done nothing but complain while Jake has tried to offer you solutions.  You have prevented him from  helping you.  Now he seems to offer to help you sell it for the price you paid (I think I interpreted that correctly). 

Overall Jake and his product have received what I feel is actually pretty good publicity as a result of your actions.  (seems hard to believe but I think so)
People now know of a device that they otherwise would never have seen.  They see what looks like pretty reasonable customer service.  You complain about an issue that seems at face value to be valid.  The company offers a solution and or multiple solutions that should help you. You publicly kind of ignore them and keep complaining.  Now you seem to be the bad guy.  Not saying that there may not be more going on in the background but Jake comes out smelling like roses and you end up with the bad smell on you, as you fail to take him up on any solution offered.  Yes, time is money but how much time have you spent and gotten nowhere near a solution.

Thanks Jeff for letting the thread play out.  It is a win-win in my opinion for the members. 

Nomad

     I'm thinking Pine said it pretty well.
Buying a hammer doesn't make you a carpenter
WoodMizer LT50HDD51-WR
Lucas DSM23-19

KiwiBro

Jake, is the joiner you suggest like the one i have already for the extension that has close to 50 parts, including 24 Allen key bolts to line up, four others for the tension plates and then a tension bolt? With  bright steel rhs with nuts tacked to it?

Do you propose cutting the 5.6m be in half and adding the joiner, so that when needing to go to 7m I have two sets of joiners in this beam?

I agree it will provide some stiffness. It will need to and can you tell me please what is the max acceptable level of hoz bounce for such a reworked beam, with extension on ?

The horizontal bounce is outrageous in two main scenarios when can't use anti bounce device. First cut on each drop, including opening cut. On large logs dont have luxury of taking small opening bites. Also Sub 4" cuts when device doesn't work. Because of the way this beam profile transfers load between planes, that hoz bounce becomes vert load on the blade.

Both vert and hoz anti bounce devices work well when they can be applied. I have both.

The locking spring, when in vert blade position is too short and weak causing the blade to unlock and try swinging back to hoz orientation. Exteremly unsafe and I can tell you things get very ugly very quickly when it happens.

What is the level of mid span beam deflection with carriage mid span and using the extension I have that you suggest the reworked beam will have and the cut will have please?
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NZJake

Hi Kiwibro,

There are 12 small m8 CSK bolts to each side of the join. Although 50 is a close estimate I guess.

Yes the inserts are the same. The little tensioners your talking about have been removed from the kit. They are no longer required. Rather a simple crown is added to the inserts. So when you bolt the beam together it's crowned. You can actually bend these quite easily to provide what ever crown you need. Place a board at each end of the inserts and give them a little hit with a sledge at the centre. Say 3mm crown (that should equate to a large overall beam crown).

Horizontal bounce...I advise all large horizontal cuts must be made in two passes. It's easier on the saw and is more accurate. I would take a 2" first cut and follow though with whatever is needed to finish the cut (with your anti-bounce unit set for the largest depth). There are many ways to skin a cat. I would be very happy to advise you on numerous productive ways to saw timber without bounce, however I have not been asked for this until now. So please give me call and I'll talk you through solutions (although I am happy to offer suggestions here too). In some cases you can actually use the collar of the saw too. Simply over bite to the collar and then move the saw back to your required smaller desired end cut at the other end. This way you are always over cutting without using any extra hp. You can also set one end over the full depth you need horizontally. Saw through at an angle then move the far end over to the same desired width, pivot and finish the cut. Its actually quite a benefit being able to independently crank each end as it opens up new options unheard of on other saws.

I don't understand why you cannot make small opening cuts on large logs. The frame is designed to slide and cut any size log available.

Spring... Haven't experienced this as of yet so happy to send you a heavier spring. It maybe you just need to tighten up the lock arm a bit so it doesn't rattle?

Crowned sag. That's really up to you, we can have a crown when the carriage is in the middle if that's what you want. We will aim for + - 3mm though. I believe that was your expectation. The cut works out to be roughly half that.

FYI I have had an idea for some time to experiment with the likes of styrofoam injected into the light weight alloy beam. I have a theory that we may experience a significant increase of strength as the outer faces of the beam will no longer distort (similar to the way airplanes are built). I've been meaning to try this out for some time but just haven't found the time to begin the experiment.

I'll take some time out on Monday and let you guys know how it went as far as the increase gained (if any). I'm just curious to know is all. We still use the light weight beams on our chainsaw mills and if there is a way to gain strength to weight ratio fantastic.

Cheers.
Jake.

Wife says I woke up one morning half asleep uttering thin kerf and high production, I think I need a hobby other than milling?

JustinW_NZ

Interesting thread.
I like the foam idea, sounds good!

Interesting hearing other peoples allowable tolerances, I've run into similar things before with different customers acceptable limits (i'm in NZ as well)
Cutting doug-fir beams currently for a timber merchant and at 6 meters they find 5mm bow unacceptable (off the saw)
Whereas a while ago a joinery customer I was basically knocking out cants for them to resaw later and they didn't care how bent they were within reason!?!

Anyway, love the look of these VERY portable units.

Cheers
Justin
Gear I run;
Woodmizer LT40 Super, Treefarmer C4D, 10ton wheel loader.

longtime lurker

Quote from: JustinW_NZ on February 01, 2015, 04:04:40 AM

Interesting hearing other peoples allowable tolerances, I've run into similar things before with different customers acceptable limits (i'm in NZ as well)
Cutting doug-fir beams currently for a timber merchant and at 6 meters they find 5mm bow unacceptable (off the saw)
Whereas a while ago a joinery customer I was basically knocking out cants for them to resaw later and they didn't care how bent they were within reason!?!

Cheers
Justin

Off topic but...
I used to put up with customers like that, then one day decided I'd had enough of it. Now I point to the deflection tables of AS 2082 (Australia's hardwood grading standard includes maximum tolerances for bow/cup/spring/twist etc) and point out that my "regular" timber has no-where near that amount of spring or bow straight off the saw. Then I explain that all timber comes from the saw bent, and that if they want it straightened we can do that - either with a plane or with the resaws but either way there is a fee to do it and it's all theirs.

Most of them get it. Most of them happily pay more for gunbarrel straight timber when they need it, and most find they didn't need it that straight all the time anyway. My moulder actually started to pay its own way from that time on because invariably people choose DAR over straightened rough sawn when the price is the same.
( paragraph removed by admin for inappropriate language)
The quickest way to make a million dollars with a sawmill is to start with two million.

longtime lurker

Quote from: NZJake link=topic=80722.msg1233987#msg1233987 date=142277756

i]FYI I have had an idea for some time to experiment with the likes of styrofoam injected into the light weight alloy beam. I have a theory that we may experience a significant increase of strength as the outer faces of the beam will no longer distort (similar to the way airplanes are built). I've been meaning to try this out for some time but just haven't found the time to begin the experiment.

I'll take some time out on Monday and let you guys know how it went as far as the increase gained (if any). I'm just curious to know is all. We still use the light weight beams on our chainsaw mills and if there is a way to gain strength to weight ratio fantastic.

[/i]Cheers.
Jake.

Jake,
Not telling you how to build a sawmill but my experience with boat building tells me you need to be very carefull with what foam compound you use. A lot of the spray foams tend to be hydroscopic - this would lead to a weight increase over time as the foam structure takes up moisture, and also leads to corrosion issues where unpainted metal is in constant contact with moisture laden foam. It might pay to seek expert advice from one of the manufacturers like Dow as to what grade of foam would be best to get the desired result with whatever grade you are using for the rail. I've seen alloy boat hulls that have rotted from the inside underneath the wrong grade of foam.
The quickest way to make a million dollars with a sawmill is to start with two million.

NZJake

Hi Longtime,

Thanks for the advise. Yes I did consider the moisture scenario. Right now I'm just looking toward proof of concept. Definitely will seek advice if it turns positive. We have filled one beam today with a Sika product. Will let you know if there was any gains tomorrow once it sets. Going to measure the deflection between a standard beam and this filled one.

Cheers.
Jake.
Wife says I woke up one morning half asleep uttering thin kerf and high production, I think I need a hobby other than milling?

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