Is my mill frame bent?

[SyrupHog]

Hi all...first time poster, long time lurker!

I'm looking for some advice regarding a potential issue with my Little Blue sawmill from Vallee Forestry Equipment (Pascal Metal).  A quick history...purchase was around August 2019...I've used the sawmill in a very limited capacity, but am getting ready to finally cut the timbers I need for a timber frame build here on the property.  

I am having a very difficult time getting the sawmill levelled.  After much fussing I finally pulled out a laser level to check things.  I have no problem getting the mill levelled side to side (using a 2 foot level on the bunks), but end to end is where the problem is.  The mill "dips" towards the middle.  Using the laser, I set the back bunk and the front bunk to the exact same level.  I then check the remaining bunks and they progressively drop lower to the point where the middle is about 3/16" to ¼" lower than the ends.  All six support jacks are down (two in front, two in the middle just behind the axel, and two at the rear), so the saw is fully supported.

Thinking about some of the boards I've cut in the past, they've always had a "swoop" to them (that's probably not the correct technical term).  I never paid much attention to this since the boards were only being used for repairing some barn board and batten pieces.  I figured the saw may have been slightly out of level even though the bullseye bubble level on the front of the frame showed it as being level (which is what the manufacture suggests). I never ran any levels or lasers to check things before today.  I'm beginning to suspect that the 'swoop' in the boards was more a result of what I'm experiencing today.

I've attached a few pictures to help show the issue as described.  Note that each photo is of the tape measure where it is resting against the top surface of the bunk and you can see the laser dot on the tape.  I've since also made similar measurements using a different laser device where I checked the rails that the saw head rolls on (see picture with 2' bubble level)...the measurement discrepancies are identical as those from the bunks.  Also of importance to note is that the measurement from the blade to each bunk surface is identical at all bunks, which makes sense, I think, given the saw head is following the bend in the frame.  I am very much beginning to suspect the frame is not true.  How could this be? It's never had anything big or heavy on it and I've always had the six support legs down to support the mill.

Being a beginner sawyer, I hope I'm just missing a simple step to level the mill properly and that it's not a manufacturing issue with the mill.  Any help and ideas would be most appreciated.

 

 

 

 

 

 

 

[tacks Y]

Welcome to the FF.

Sure does look like it is not straight. What is the height at the end where the laser sets? Maybe no one else (or not many) have checked theirs this way. Some wood may sag this much under its own weight. Is that a 6' level or just a 4'? Can you a  see bow using it? I would think you could make it straight with a jack and the weight of the mill, slow and steady one rail at a time.   

[chet]

I notice the mill is in the center of the track in your pics. Move the mill to each end and recheck your measurements to see if the mill weight is causing the problem.  If the measurements change, try setting the height of your bunks with the mill directly over the jacks at each location.

[rusticretreater]

I've since also made similar measurements using a different laser device where I checked the rails that the saw head rolls on (see picture with 2' bubble level)...the measurement discrepancies are identical as those from the bunks.

Yeah, based on your measurements the frame is bowed. This is either a manufacturing defect, happened during shipping or subject to some abuse during use.  I would think that the manufacturer would use a jig or flat table to assemble the frame, so it likely would have been mishandled during shipping.  Such as someone picking up one end with a forklift and dragging it with all the rest of the weight of the head/motor/etc. sitting on the middle.

I would check on your warranty and try to work something out with the company.  It will be a bit hard to explain how you are just finding out after 3-4 years.  Finding someone to straighten it out won't be fun and of course be a tad expensive.

[Dan_Shade]

My limited experience with 4 post mills was that the frame was more flexible than I had anticipated. 

If you change the pressure on the jacks/outriggers does it influence the swoop? 

[Ljohnsaw]

When you set the 6 jacks (crank them up), do you have the same amount of turning pressure on all six?  On the middle set of jacks, have you lifted the tires off the ground?  If you lift the middle to the point of the ends being just barely touching, what does the laser show?  I'm thinking the bed might be a little flexible and you need to jack up the middle a little more to true it up.

[barbender]

 I was working on typing a long reply on how to set your mill up. It was getting complicated and I got bored with myself, so I know you would've too😊

 Here's the thing- I bet the frame on your mill is flexible enough that even if it is bent, (I doubt it is) using the jacks you can straighten it out for sawing. The frame of every mill out there flexes to a degree, the secret is making sure what that flexible frame is set up on is solid. 

 Here's something else to check- if you have all the jacks up, I bet your frame has a crown to it if anything, opposite of the sag you are measuring now. 

[kelLOGg]

If you are sure the frame is bent (I've been there) then consider a low-end body shop.
help! I warped my frame welding in Sawmills and Milling (forestryforum.com)

[Stephen1]

I agree with Barbender,
Do you have a level concrete floor you can try setting the mill on? Then you can possible see what you are dealing with.
I would also call the manufacturer as they might have some ideas to help you. 

[YellowHammer]

A can flex my LT-70 frame quite a bit from one end to the other with just the outriggers.  I would try making adjustments with the jacks.

[Crossroads]

My Lt40 has a crown in the middle and I have to set it up with extra pressure on the end jacks. After milling for a bit and mill has settled, I typically have to add a couple more cranks on the end jack to remove the crown again. 

[mike dee]

You need to measure level from the top of the rails NOT the frame. The frame is not a useful measurement because it's there only as a support for the rails.

[SawyerTed]

Welcome to joining the discussions!   Sorry it is to address a problem.  Hope to see some of your sawing once this gets worked out. 

+ 1 on a level concrete pad to set up on the do the checks.  Then use the middle jacks to see if there is frame flex, as others mentioned.   Then check your bunks. 

In the photo of bunk 2, do I see a slotted adjustment plate on the end of the bunk at the frame?   That maybe part of the issue as those slots may have allowed some movement of the bunks.  Even smaller logs could cause some slippage of the bunks. 

[chet]

On occasion I have stretched my mill out to 24 feet. At that length it can flex quite a bit. I have jacks at each bunk location. When I set up I will move the saw head directly over each jack location as I adjust them. I can get my rails dead flat doing this. Before I started doing it this way, I had the same problem as your finding. I also found it quicker to set my height in the center first, then adjust both ends up to match.

[Hackeldam Wood Products]

You may be overthinking level somewhat. The mill needs to be level enough so the head does not roll on it's own. If you are out much side to side you should back on a block.

I see a lot of misunderstanding about out riggers. They are there to support the mill,not jack it up. Steel is a lot more flexible the you may think,to much tension on the jacks can definitely tweak it.

If the blade is the same measurements to the bunks it is unlikely the four rollers spaced apart could follow the "dip" in the frame. It also very unlikely both main rails would be bent the same.

Take any tension you have off the jacks and lay a known straight edge on the bunks and see if it lays squarely on all the bunks.
Or run a string to check it. If it does cut some lumber and check the results. A lazer may be to good a tool for this job.

If it really had a bow in the center I think the blade would begin to dive and not recover. I doubt the blade would follow the mishapened rails.

[chet]

In my case above if I set up with the millhead on one end only, and level it, it will be low in the center 'every time' when I later move the mill head over the center. This does not happen though if I setup on a hard surface such as concrete or blacktop.

[SyrupHog]

Thanks everybody for all the ideas and sharing your experiences.  As per suggestions, I moved the mill and set it up on the concrete slab where I'll be building the sugar shack.  I've jacked the mill up and gone thru the steps of levelling things.  I also moved the laser level onto a tripod so it was not resting on the mill frame.  The good news is that this indeed seems to have helped.

Measuring each bunk produces a result where the middle bunks are perhaps an ⅛" off, maybe not even that much.  Much better than before.  I also took measurements at each bunk when the saw head was overtop and the measurements stayed the same.  I haven't checked the rails themselves yet, but I'm hopeful things will be ok.  When the weather improves later I'll see if I can get out and do this.

Interesting comment on the use of outriggers from @richhiway.  I have jacked the mill up, higher than I normally would.  At this point the tires are nowhere near touching the ground. I was going to play with lowering the mill to the point the tires were just off the ground (maybe an inch or so) and see if anything changes...it shouldn't.  This would make me more comfortable too, since I find the mill is fairly wobbly, and more so the higher it's jacked up.  I'm not a huge fan of where the jacks are located on this mill (inside the frame), the base they create feels narrow.  Has anybody added outriggers to their mills to help with stability?  Something that goes out at a slight angle from the sides of the mill seems to me it would help.

[Magicman]

I prefer that my tires are firmly on the ground to provide additional mill support/stability.

[Hilltop366]

If it really had a bow in the center I think the blade would begin to dive and not recover. I doubt the blade would follow the mishapened rails.

My cousin has a old LT15 that he made a set of top rails with a gradual upwards bow in them to use when cutting boat deck beams for lobster boats. It puts a arch on the top of the beam for the boat builder and saves them from having to cut the arch. The issue has been getting enough (usually spruce) logs to do this as the lobster boats have been getting wider.

[justallan1]

Just my opinion here....
I found that my mill was getting jostled around to much using the crank up jacks and went with setting the tracks on shoring blocks 6-8" wider than the width of the tracks, then use whatever scraps as wedges to get it sitting level, then use drywall screws to fasten the blocks to the shoring.
I use a string-line down one side of the tracks and then a 4' level to match the sides.
My experience says that just flipping a large cant can pound any single jack and block into the ground way easier than using big wide chunks of shoring the width of the mill. Yes, it takes a few more minutes initially, but my mill stays rock solid.

[Stephen1]

I prefer that my tires are firmly on the ground to provide additional mill support/stability.

Wood Mizer recommends that the tires stay on the ground for Stability, I would definitely leave your tires on the ground. I bet your mill manufacturer says the same. 

[1938farmall]

syrup, the middle sentence in your last post gets my attention.  i would level the rails that the head runs on first; then adjust the bunks to be a standard height above/below the rails.

[Brad_bb]

Level relative to gravity, what your laser level is doing, isn't nearly as important as the top of the bunks being co-planer, and the rail or rails that the mill head rolls on is also co-planer and parallel to the bunks.  When you set up a mill on a site, you check for level roughly so that your logs don't roll one way or another and so that your mill head rolls nicely and doesn't want to run downhill.

[KirkD]

If you run a string or chalk line from one end to the other on the rails what do you see?

[OlJarhead]

When I had the twin rail mill that I put on a trailer (LT10) I always made sure it was on the same plane.  Level isn't as important as the same plane.  Meaning no twist and no dips.

I set it up much like I do the LT40 today:  Drop trailer jack/outrigger at front, drop rear, free head and move to the tongue/front.  Set rear outriggers tight to the ground.  Run head to the rear, set fronts tight to the ground.  Run head to the front, check rears and adjust as needed, run head to the rear, check fronts.  Repeat as needed until everything is SOLID.

To level, not you fine tune adjust each outrigger until it's level.

The important part is making sure they are SOLID to the ground first or they will sink as you make adjustments and reak havoc on the leveling ;)

Hope that helps!