Cantiliver Head Rail Stock Hardness

[Left Coast Chris]

I built an LT 30 clone and used a round stock rail for the top rail welded to the frame.  It is welded to the frame the same as  all Woodmizers that Ive seen.  The heads full weight is on the rollers and the rollers have created a flat spot on the round stock.  That makes the head roll alot harder even though it has debris scrapers and stays clean.   

The obvious problem is that the round stock I used is too soft.  Probably mild steel, maybe A36.    Does anyone know what the designation of the steel for the round stock rail should be?   :P   --thanks for the help --

[D Martin]

would the round stock you used be the same hardness as say maybe sprinkler pipe,  schedule 20 or 40 ? how could you tell? maybe use that instead?

[D Martin]

what did you use for wheels if i might ask?

[TexasTimbers]

Just how flat, is flat . .  can you post a picture?

Mine has a slightly perceptible flatness to it but it does not affect performance. I will post a pic of mine to give you something to compare by. My chassis has probably 5000ish hours on it.

[Left Coast Chris]

Its been raining for days here so I can't get a pic for now.  The flat spot is about 1/4" wide (large).   If it lets up, I will post a pic.

Mild steel is A36 or 36,000psi tensile strength.  Steel used for shafts is much harder.  I think that is what I need but not sure since it comes in different hardness.

Hardness is tested by an impact type device with penetration measured.

Water pipe is definately soft if even 36k psi.  Probably not a good bet.

Not sure what my rollers are except that they are definately hardened steel.   My dad bought them.  They are industrial quality.

[1938farmall]

lcc, here is some general info on different round stock which could be used for roller guides;  low carbon - 1018 or 1020 yield=32k, brinell hardness=116.  medium carbon - 1040 or 1045 yield=42-45k, brinell hardness=149-163.  both the 1040 & 1045 would require some special attention to welding having .40-.45% carbon content, but will readily take flame hardening after welding to your frame resulting in a brinell in the 400's.  if you have access to steel in the 41xx series it will also flame harder easily (air hardens) but is even more difficult to weld.

i'm thinking like d.martin, that the wheels might be a possible problem source.  if they are relatively small, there will be a greater point load on the guide bar.  also, if the radius in the wheel doesn't match the radius of the guide bar, that could also flatten the top of the guide bar.  for what it's worth.  al

[D Martin]

 Stab in the dark for me but, did it used to roll easier?  Could be both, one affecting the other,  also round stock has a large surface area, my  bandsawmill wheels ride on the edge of angle, Not much  friction/resistance or sawdust buildup. My chainsaw mill (wich I  know is not a great comparison cause of the weight, wich afects friction and forward (enertia?) -has unistrut for track and casters made for it, but is not as smooth a rider even without the  heavy weight of a bandsaw motor etc..

[D Martin]

inertia- pardon my spelling

[Left Coast Chris]

This picture was taken with the head all the way to the end of the bed.  That is where the flatened part of the rail is the smallest.  It gets bigger towards the middle of the bed where all the short cutting occurs.   The mill only has about 200 hours on it.

Note that it has two approx. 1-1/4" diameter rollers on each vertial head post (4 total on the top rail).  My gut feeling is that the rail is too soft.   It would be good to know what Woodmizer uses for hardness of the rail and if they ever have to replace rails due to flattening.

[Dan_Shade]

woodmizer may well do a process to harden the entire frame after it is welded up.

There is a post somewhere on the forum that older woodmizers may have a similar problem that you're talking about.  I think cedarman talked about his old mill wearing down in the middle, but it probably had way more than 200 hours on it.

[Tom]

I was told, years ago, that the rail was quite hard.  I have no way of knowing or measuring how hard, but it isn't mild steel.

The welding took place in a slow and planned operation that allowed fro and inhibited expansion that would make for a crooked weld.

The rails might vary from side to side, but the top edge was level with beam.  The side to side isn't all that harmful.

I developed flat spots on my 1990 LT40, even though it was on a hardened rail.  It was worse in the first 10' and hardly existant  past the 16 foot mark.  I never noticed that it affected the lumber.  I was concerned about the cam followers not being able to turn eventually, but after almost 2 million feet, the mill was still functioning properly.

[musikwerke]

I have a 1987 LT30 with 2400+ hours and it has flat spots on the top and bottom rails.  Just as you've described, the widest flats are in the middle and taper to almost nothing at each end.  The bottom rail has worn the worst; again, widest flat in the center 8 foot span and tapering to barely detectable at each end.  The only unpleasant conversation I've ever had with Wood-Mizer was with a fellow in the technical department on this subject.   Another Wood-Mizer tech I met in person at a local open house told me that Wood-Mizer doesn't like to discuss this flaw in their earlier mills.  So far, I can not detect that the quality of lumber is suffering because of these flat spots.  But then, most of what I cut is 12 foot stuff and under.  I suspect that on my mill, the wear on the bottom rail will cause an alignment problem long before the top rail will, if ever.  As soon as I can unearth the correct parts and pieces from my junk pile, I'm going to build a grinding attachment that will "ride the rails" and allow me to dress the bottom rail to a uniform width over its entire length.  I was hoping that Wood-Mizer had developed such a fixture that could be rented but not only do they not have one, I was sorry I asked.  Another member on here wrote about dressing the bottom rail on his Wood-Mizer with a right angle grinder free-handedly.  I'm not that brave.

[1938farmall]

music... one thing to think about is that the rails may have been flame-hardened or induction-hardened at the factory.  you can check this by trying to file the surface - you will notice the hardness easily.  if you find that they are hardened it likely that the hardness is only .04"-.06" deep and if you grind that off there is only mild steel underneath.  on the other hand, if you find it soft when you file, then it was not heat treated and grinding should be helpful. al

[Brucer]

I can't give you actual numbers, but I know that they're extremely hard.

I once asked the local Wood-Mizer rep about rolling the carriage ahead of it's travel position in  order to get more traction with my 2WD truck. He said it would work, but to be sure to clamp a pair of vice-grips to the rail on either side of the carriage so it wouldn't roll . I tried the vice-grip trick out of curiosity (at the end where the carriage doesn't ride) and they didn't leave a mark.

I also "tried" to saw through the top rail with my chainsaw and it didn't leave a mark either. Sure didn't do the saw chain any good :(.

Since welding will often temper (i.e. remove the hardness from) hardened steel, I suspect they do some kind of heat treating after the rails are welded. I doubt that they harden the whole frame, as that would make it very brittle. I suspect they use some kind of induction hardening to just harden the rails.

[backwoods sawyer]

My bottom rail has a flat face in it as well and when I talked with woodmizer about it they offered to send out there mobile crew to regrind the rail at an hourly rate and estimated the job to take 8 hours. They got something they send up and down the rail to reshape it now. He suggested that I take a side grinder with a wire wheel on it and clean off all the burs, which I did. My rail still has a flat face for the rollers to run on and it cuts straight true wood. I pull all the bottom rollers off about every 200 hours to grease them all and change the bad ones out. The bottom rollers pick up a lot of road grime when the mill is being towed a lot, and the grime works its way into the rollers. I find that the bottom rollers have half the life span of the top rollers and a dead roller will wear the rail down quicker then anything.

[Left Coast Chris]

Auh...huh...  good info.   I may have a dead roller then.  I will have to check them out.  Mine are adjustable so I believe I can adjust them so they are not riding on the exact same spot.   Cleaning the burrs off the rail sounds like a good idea also. 

Since my carrage is propelled by rope and hand crank the extra push it takes to saw has some wear and tear on the sawyer also!   :-\

[Fla._Deadheader]

I read that WM uses a very hard rail, AND hardens it more at the factory. How hard is hard ???  Don't know.  : :

  We used common angle iron "V" up on top of the beam, and, down on the bottom of the beam. We used 2 bearings as rollers, instead of cam followers, and there is now, a slight groove on the wear sides of both angles, but, it's probably .010 or so, very slight. Our head assembly probably outweighs WM by 100 pounds or so.  : :

  As stated, a bad bearing or cam follower will drag and maybe scrape minute amounts off that rail you used. If you are so inclined, change the rails to as hard as you can find. Sure can't hurt anything, although that's a LOT of work to go through.