Build Track & Bunks for millhead

[shadowdev]

Hi Everyone,
I need to build the track system for a millhead and have spent many hours online doing due diligence before Q&A, however some questions remain.


Overview:




The millhead wheels are slotted 5/16".

I'm doing a standard track build of angle iron & bunks supported (lag screws) along straight 7x7x20' pine.
On ground layout, shimmed to level, no adjustable foot pads.
Using this image as a general idea but don't know what the dimensions of the Angle or bunk material are.



Planning to use 20'x3x4x5/16" angle for the track and 2x4x3/16" box material for the bunks.
Local steel suppliers will cut bunks (45° ends) & do all the hole drilling (3/8") as well, so I'm looking good for getting the parts and will weld log stops & clamps afterwards.


Question(s):

I'll be cutting relatively long lengths, nothing shorter than 6-8ft.
Several forum posts of Bunk spacing but nothing definitive.

• Advice for bunk spacing as 2,3,4 or 5ft OC?
• Will 1/4" Angle material work or will the closer tolerance 5/16" angle fit be better in the wheel slots? I imagine 5/16" is best but figured to ask.
• Is 3x4" Angle track material necessary or will a 3x3 or 2x3" work? Looking at images of most show the bunks much taller than the track rail, however I imagine 3x4" angle will nearly meet the top edge of a 2x4 bunk.
• Bunk material in 2x4x3/16" thickness sound reasonable?

Any other advice?

Thank you,
SD

[Ljohnsaw]

My track rail is 2x3x.25 welded every 2 feet or so to 2x4x.25 box frame.  So, I would think 2x3x.25 rail would be more than sufficient mounted on your wood beams.  I would NOT do 5/16" for a several reasons. 1) cost, 2) weight, 3) might bind in your wheels.  The rails are really only supporting your cutting head.  The weight of log on the bunks is supported by your beams.

How low can your band get in relation to your wheels?  Your bunks need to extend above the tracks that amount (or 1" less for final board).  If you go higher, then that will encroach on the diameter of log you can pass over with the blade raised.  Might not be an issue for you but something to consider.

Bunk spacing, not too close if you have curvy or knotty logs - makes for interference issues.  I'd go at 3' or 4'.  What about 4' and having one or two that can be moved?  Weld on the ends a tab to keep them from rolling over.  Or a big enough tab that you can drill a hole away from the angle track and run a temporary lag screw to keep them in place.  Then you can mill up odd sizes easily.

Also, are you sure you want to have it on 20' 7x7's?  What about just having cross ties spaced out then you don't have to worry about your beam flexing with the humidity (damp ground/dry air above).

[shadowdev]

My track rail is 2x3x.25 welded every 2 feet or so to 2x4x.25 box frame.  So, I would think 2x3x.25 rail would be more than sufficient mounted on your wood beams.  I would NOT do 5/16" for a several reasons. 1) cost, 2) weight, 3) might bind in your wheels.  The rails are really only supporting your cutting head.  The weight of log on the bunks is supported by your beams.


Hi John,
I really appreciate your quick & thoughtful reply.

The 5/16" cost is nominal and weight is a one time carry and doable ;).
The 5/16" angle was 'apparently' what a distributor said came with the saw or rather 8mm (.31" or 5/16"). As well there was concern that the slight amount of play (1/16" on each side) might allow the millhead, when pushed from one side, to actually tweak and possibly jump track.

How low can your band get in relation to your wheels?  Your bunks need to extend above the tracks that amount (or 1" less for final board).  If you go higher, then that will encroach on the diameter of log you can pass over with the blade raised.  Might not be an issue for you but something to consider.

Hmm, how low can it go?; good question, lemme check that...
Ok, the band at it's lowest is 5" above the wheels.
Could you please elaborate a bit on what you mean here "Your bunks need to extend above the tracks that amount (or 1" less for final board)"?

Oh, wait, are you saying that the bunks need to extend 5" above the top of the track to clear the lowest cut? Hmm, not sure I really understand this clearly and having trouble visualizing it.


Bunk spacing, not too close if you have curvy or knotty logs - makes for interference issues.  I'd go at 3' or 4'.  What about 4' and having one or two that can be moved?  Weld on the ends a tab to keep them from rolling over.  Or a big enough tab that you can drill a hole away from the angle track and run a temporary lag screw to keep them in place.  Then you can mill up odd sizes easily.

4' sounds like a reasonable number.
Great advice & will definitely do that with a couple bunks!  I'll just leave a couple loose and move around; add a tab or two and lag as needed. Excellent! Thank you.

Also, are you sure you want to have it on 20' 7x7's?  What about just having cross ties spaced out then you don't have to worry about your beam flexing with the humidity (damp ground/dry air above).

Actually, didn't think of that. So just put 7x7 cross members under each bunk?
Seems like a cost saving and overall better idea. Oh, maybe I had a concern that the cross members would impede log stops and clamps.

Thank you again John,
SD

[doc henderson]

so the blade at its lowest is 5 inches off the level of the bottom of the wheels.  the bunks between the tracks could be 4 inches above the tracks, and still leave an inch to saw a board at the lowest position (saw) and make a 1 inch thick piece, and also be 1 inch above the bunk so you do not hit it with the saw bans.  most mills are like this if you look at the pictures.

[doc henderson]

 

 


 


 

so my blade at its lowest position on the mill, is still 1 inch above my bunk, and 1/4 inch above my cant hook.  the hook is 3/4 of an inch tall.  since a pic is worth a thousand words... sorry for the lengthy post.  

[doc henderson]

your original diagram actually shows it very well

[Crusarius]

if you have 5/16" wheels you do not want 5/16" track. 

Movable bunks could be very nice. 

Some ways I wish I did that on mine. but instead I did some out of the ordinary bunks. I used a combination of 2x2x.188 and 2x6x.188 the 2x6 is spaced 36" oc. the 2x2 is space 12" off each of the 2x6. The 2x2 is what my log clamps slide on. Which is the reason I did it this way. plus I can support a 12" long piece. the mains at 36" oc are a bummer I think I would have been better at 30" because it seems I am always 3" short of making it to the next strong main. You are not putting sheathing on the bed so spacing only matters for log support. it does not need to be even. Most of the time I use 8' of my 24' bed. always the front 8' the rest only gets used on long logs.

I am not a fan of angle iron for structural members, because it offers very little torsional strength (twist). If you got some 2x4x.120 box then put a 2x2x.25 angle on it leg up that would probably be the ultimate setup.

Also keep in mind the open bunks will collect alot of sawdust and water. if they do not have a way to drain they will get nasty!!

I also highly recommend some type of adjustable foot. Shimming the frame every time you bump it is going to get old fast. and you will bump it.

[shadowdev]

your original diagram actually shows it very well

Hi Doc,
Thank you very much.
The pictures did the trick and I get it now.
So a 2x4 bunk will clear the 5" head height leaving a 1" board.
Got it!
Thank you again,
SD

Oh, wait, not exactly huh?
It dawned on me while reading Crusarius' post below that the relative distance between the blade and the bunks should also include the height of the track angle too, correct?
So a 5" tall millhead riding on a say a 2" angle (7" total) would clear a 4" bunk by 3"? Is that right? So I'd actually need 2x6" bunk material to close the gap?

[shadowdev]

if you have 5/16" wheels you do not want 5/16" track.

All good points Crusarius,

So a 5/16" slot running on 1/4" angle shouldn't tweak to one side and jump track under blade tension while being pushed?

Movable bunks could be very nice.

Some ways I wish I did that on mine. but instead I did some out of the ordinary bunks. I used a combination of 2x2x.188 and 2x6x.188 the 2x6 is spaced 36" oc. the 2x2 is space 12" off each of the 2x6. The 2x2 is what my log clamps slide on. Which is the reason I did it this way. plus I can support a 12" long piece. the mains at 36" oc are a bummer I think I would have been better at 30" because it seems I am always 3" short of making it to the next strong main.

You are not putting sheathing on the bed so spacing only matters for log support. it does not need to be even. Most of the time I use 8' of my 24' bed. always the front 8' the rest only gets used on long logs.

Oh, ok, I gotcha, so bunk spacing is something I want to consider with regard to what will be cut most often, which will be 12' or less. There are a few 18'-20' cuts planned but not often at all.

I am not a fan of angle iron for structural members, because it offers very little torsional strength (twist). If you got some 2x4x.120 box then put a 2x2x.25 angle on it leg up that would probably be the ultimate setup.

I thought the same thing but was unsure of how far to space the holes in the bunk ends and figured that a 3" angle would give me enough room for 2 bolt holes as I'll be screwing through the bunks, angle and into the 7x7 supports.
With 2x2x1/4" material the working flat edge will be 1.75" which I thought was tight for 2 bolt holes.

Also keep in mind the open bunks will collect alot of sawdust and water. if they do not have a way to drain they will get nasty!!
Aah, yeah, right, I bet they do.
I'll be sure the bottom edge has holes for drainage.

I also highly recommend some type of adjustable foot. Shimming the frame every time you bump it is going to get old fast. and you will bump it.

Hmm, yeah I see your point.
The idea was to level the 7x7's, layout the angle and bunks on top and lag screw through both into the 7x7's. The ground is very stable but I imagine a bump will throw the whole thing off huh?

Maybe I should abandon the idea of the 7x7 cross-members all together and just go with adjustable feet? Besides making them I'm unsure where to get the feet, I'll do a quick lookup.

Thank you Crusarius,
SD

[shadowdev]

your original diagram actually shows it very well

Hi Doc,
Thank you very much.
The pictures did the trick and I get it now.
So a 2x4 bunk will clear the 5" head height leaving a 1" board.
Got it!
Thank you again,
SD

Oh, wait, not exactly huh? It dawned on me while reading Crusarius' post that the relative distance between the blade and the bunks must also include the height of the track angle too, correct?
So a 5" tall millhead riding on a say a 2" angle (7" total) would clear a 4" bunk by 3"? Is that right? So I'd actually need 2x6" bunk material to close the gap?

Accidental Duplicate post.

[btulloh]

My saw track looks a lot like yours on my HM-126 but the bunks are 3x5. The top edge of the angle iron is milled, presenting a flat surface for the wheels and a straighter edge than standard hot-roll angle iron.

Even though the mill head for an HM-126 is fairly light relative to more expensive saws, there's no tendency for the wheels to jump off or even lift one side during a cut.

Angle iron is the low end of the track spectrum for sure, but it's workable as long as the base is stable and accounts for the inherent shortcomings of angle iron.

My base is simply 6x6 cross ties with 6x6's running under the length of the tracks. Adjustable feet allow for any tweaking needed.  

Lots of ways to get to the finish line. It just depends on how much you want to spend on materials.  As you go up the commercial mill food chain tracks get heavier and more robust.

My bunks are 40" c to c and that works pretty well. One movable temporary bunk would be nice.  Ljohnsaw had a good take on having bunks too close together.  The feet are bolted to the 6x6's which is a necessity. Lots of bumping and jostling especially max sized logs  

[shadowdev]

My saw track looks a lot like yours on my HM-126 but the bunks are 3x5. The top edge of the angle iron is milled, presenting a flat surface for the wheels and a straighter edge than standard hot-roll angle iron.

Even though the mill head for an HM-126 is fairly light relative to more expensive saws, there's no tendency for the wheels to jump off or even lift one side during a cut.

Good to know btulloh. Do you know the thickness of your own track wheel & angle?

Angle iron is the low end of the track spectrum for sure, but it's workable as long as the base is stable and accounts for the inherent shortcomings of angle iron.

My base is simply 6x6 cross ties with 6x6's running under the length of the tracks. Adjustable feet allow for any tweaking needed.  

Ok, so you have 6x6's crossing under 6x6's running the length. Got it.

Lots of ways to get to the finish line. It just depends on how much you want to spend on materials.  As you go up the commercial mill food chain tracks get heavier and more robust.

My bunks are 40" c to c and that works pretty well. One movable temporary bunk would be nice.  Ljohnsaw had a good take on having bunks too close together.  The feet are bolted to the 6x6's which is a necessity. Lots of bumping and jostling especially max sized logs.

I see, so you've bolted the feet to the 6x6 long lengths.
Do you adjust them often?

Yeah, that's good advice too. I'll definitely have a bunk or two that can be moved about.

Thanks for the help btulloh,
SD

[btulloh]

Probably 1/4" angle and 5/16 groove in the wheels. The groove needs some clearance and lateral play there'll be a tendency to bind. 

[btulloh]

My base. It would be better to be a little higher, but fairly comfortable working height. This height for the base andlog deck suits my main log moving equipment which is a Kubota L3250 with pallet forks on the rear and bucket forks on the front. Many ways to build a base. Some people prefer a trailer. 



 

 

[btulloh]

BTW - I wouldn't recommend having the cross ties stick out past the track as far as mine. There are plenty of trip hazards without building them into the infrastructure. 

[Crusarius]

I like the idea of 3x5x.25 angle put the 5" leg flat on the bottom of the cross pieces. give you plenty of meat to bolt to if you want to bolt it, I would personally lean towards welding but I have that capability. you can then leave a 1.5" gap between the end of the bunks and the angle to allow for sawdust and water to drain out of the bunks. Also give you the ability to hose it out once in a while.

btulloh, are your bunks bolted to the angle? is there any diagonals in there to keep it from racking?

[btulloh]

The bunks are bolted to the angle.  No diagonals.  Of course that makes the potential for racking, but there are enough connections that it doesn't (in the short term).  It really needs to be fastened to a trailer bed or a base to make everything stable in the long run.  Most of us start out with it just sitting on something when we first get the mill and want to saw a few logs.  That's ok, but flipping a large cant makes the thing want to walk sideways when it's just sitting on something.  That would be true no matter how the track is constructed.  (Look at what JoshNZ went through with his outriggers getting bent.)

I saw mostly logs in the 20-25" range and they transfer a lot of energy to the mill bed when flipping.  The bed's got to be able to absorb that whether it's mounted on a trailer or on a base of some sort.  My base is pretty basic but works fine and is very stable.  It's on very stable ground with gravel and crush run pads under the cross ties for drainage.  Each cross tie is spike down with a piece of 18" rebar at each end.  Everybody tends to do it to suit their needs and situation, and most everybody ends up with something workable.

There haven't been any issues with water or debris build-up inside the bunks. They are powder coated inside and out.  I have to blow off the sawdust at the end of the day from the track and everything else and the bunks get blown out in the process.  I'm not saying it's the best design, it's a design that works and is typical for these lower priced mills.  The bed and track of course dictate the accuracy of  the lumber that gets sawn, and so using the best materials and construction possible is worth the price of admission.

I think you're right about the 3x5 x .25 angle being a good choice.  That's what this is (or maybe 3" x 4"), with the top edge milled flat.  One drawback to the angle iron, especially 5" on the bottom, is that it encroaches on the inner space between the members and that limits the travel of the log clamps.  The HM126 track is 30.5" rail to rail, so subtract 10" (or 8"?) from that and it's getting pretty narrow in there.  It works though, but it makes it a little tough when you're dogging a 26" log.  All manageable though.  Making the bed can solve that.  Of course, using rectangular tube with a bit of angle welded to the top for the  track is a much more robust approach.

[shadowdev]

Thank you very much btulloh & Crusarius.
The pictures and clear instruction help immensely.

I'll be ordering steel early next week.

I think the most important question being answered is that the 1/4" track material will do the job without fear of the millhead jumping. That helps settle my mind quite a bit.
The question arose when looking at just how much slack space there was in the wheel slot when comparing between 1/4" & 5/16". See the image below shows the actual slot as just over 5/16".



 


Leaning toward a 2x3 or 3x3 angle with the 3" flat down.

I'd weld the parts together but the mill is only going to be in place for 1 season then moved to a final location in a couple of years, so I can weld then. Plus I'll have time to get familiar with the saw and it's workings.

I'll be sure not to have any cross pieces sticking out too far.

Many Thanks again everyone,
SD

[Crusarius]

If you are worried about it jumping make a clip to go around the track. I actually used 3/8" plate welded to the side of the 2x6 box. I was able to bolt a piece through the same bolt as the wheels and it wraps the 3/8 enough it cannot come off.

[shadowdev]

If you are worried about it jumping make a clip to go around the track. I actually used 3/8" plate welded to the side of the 2x6 box. I was able to bolt a piece through the same bolt as the wheels and it wraps the 3/8 enough it cannot come off.

Thanks Crusarius, will do!

[shadowdev]

Hi Everyone,
Been away for a couple of weeks & wasn't able to place the steel order.
Just returning and finishing the parts list, with a couple of final questions.
Could I get a Yay or Nay on the list below?

Based on the band height from the wheels of 5".


Track Angle material: 2x3x.250  (Mill head riding on the 2" leg, the total band height would be @7" from wheels)

Bunk Rectangle material:
Question: Should I use 6x2 or 6x3x.188?  (The 6" bunk height would provide the 1" clearance from the lowest position of the band)

Log stops Square material: 1.5 x .125" & 2.0 x .125"
Question: (The 1.5" will fit into the 2", correct?)

Many Thanks Again to All,
SD

[Crusarius]

if you are putting the angle on the bottom of something you will lose 1/4". But that is a good thing. I have my thinnest cut at 5/8" board. Usually my last board is 1" but its nice to have room to go thinner if necessary.

I would use 6x2 mostly because if you use 6x3 thats another inch of space that bark and junk can land and cause issues with your wood being flat on the bed (more area to brush off).

I also highly recommend stainless or some other bunk covers. I get black lines on my oak immediately from my bunks. The next version I build will use HDPE on top of the bunks to keep the boards clean and make it easier to slide them around.

[Ljohnsaw]

My opinion, others may think otherwise, but

Using the 2x3 with the 2 being upright is a waste of money for the 3" width.  You might as well go with 2x2 or 1x2 (1.5x2?).  The 3" being flat gives you no added rigidity to your track - just extra weight and cost.

6x2 will be fine.  Again, the 3" width give no additional rigidity.

The 1.5 will fit in the 2 if, and only if, two things line up for you.  First, the 1.5 will need to have round corners.  Sometimes it come really square and the sharper corner won't fit the 2" inside corners without a lot of extra work/grinding.  Second, you will need to remove the weld seam on the inside of the 2".  I did it with a 4-jaw chuck on my lathe.  There is a guy on YouTube that made up a really cool tool to zip out the weld seam with a drill.  Worst case, a file and a bit of time.

I used 2" for my uprights and 2.5" for the sleeves that they rid in.  Depends on how big your logs will be.  Since I am milling up 20 to 36" diameter logs weighing a few thousands pounds each, I opted for bigger, stouter material.  Haven't bent one yet (but put a few saw cuts in them :).

[shadowdev]

if you are putting the angle on the bottom of something you will lose 1/4". But that is a good thing. I have my thinnest cut at 5/8" board. Usually my last board is 1" but its nice to have room to go thinner if necessary.

I would use 6x2 mostly because if you use 6x3 thats another inch of space that bark and junk can land and cause issues with your wood being flat on the bed (more area to brush off).

I also highly recommend stainless or some other bunk covers. I get black lines on my oak immediately from my bunks. The next version I build will use HDPE on top of the bunks to keep the boards clean and make it easier to slide them around.

Thank you Crusarius,
Good advice and I'll check the pricing for stainless.
SD

[shadowdev]

My opinion, others may think otherwise, but

Using the 2x3 with the 2 being upright is a waste of money for the 3" width.  You might as well go with 2x2 or 1x2 (1.5x2?).  The 3" being flat gives you no added rigidity to your track - just extra weight and cost.

6x2 will be fine.  Again, the 3" width give no additional rigidity.

The 1.5 will fit in the 2 if, and only if, two things line up for you.  First, the 1.5 will need to have round corners.  Sometimes it come really square and the sharper corner won't fit the 2" inside corners without a lot of extra work/grinding.  Second, you will need to remove the weld seam on the inside of the 2".  I did it with a 4-jaw chuck on my lathe.  There is a guy on YouTube that made up a really cool tool to zip out the weld seam with a drill.  Worst case, a file and a bit of time.

I used 2" for my uprights and 2.5" for the sleeves that they rid in.  Depends on how big your logs will be.  Since I am milling up 20 to 36" diameter logs weighing a few thousands pounds each, I opted for bigger, stouter material.  Haven't bent one yet (but put a few saw cuts in them :).

Thank you ljohnsaw,
The 3" flat is simply to have room to drill two holes in the bunk material for a bit more stability.
I'll check with the supplier on the 1.5 -> 2" fit as well
Thanks again,
SD