Edger not cutting straight

strunk57 · December 06, 2018, 05:15:50 PM

Hello All! I have a marathon edger that I have spent a small fortune on. I just got it back from the machine shop. I had the sliding blade arbor fixed, and the main shaft checked. Everything is a go. First board ran through perfect. Then from there every board that ran through both blades cut crooked as in the first 5-6 ft was straight then curved. Still cutting the target width but crooked like something is pulling the board as it come out of the end. Could it be the edger isn't sitting perfectly level? Any other opinions on what could be going wrong?

redbeard · December 06, 2018, 05:28:43 PM

Could tension in the boards be causing you grief?
Maybe run some plywood through it.
Just a thought.

Southside · December 06, 2018, 05:53:34 PM

Is that a belt or roller feed?

strunk57 · December 06, 2018, 07:38:13 PM

Roller

Southside · December 06, 2018, 07:42:32 PM

Tension higher on one side than the other allowing slip?

moodnacreek · December 06, 2018, 08:16:35 PM

This is a very common problem. A feed roller edger with no out feed fixed guides or shifting guides has to cut straight on it's own. The reason many edgers have no guides is because peeling bark strips and other things get caught in them. Also some operators don't need real straight boards. The mandrel must be square to the frame or infeed , one edge fence. Next the feed rolls are to be parallel to the mandrel . Do this with a stick cut short with a wood screw in the end for an adjustment and to gage between the mandrel and feed roll and make another one to fit feed roll to feed roll if needed. If you have dead rolls infeed or out feed they also must be parallel to the mandrel and feed rolls. Any thing the board touches must be flat level and of equal bearing and friction. Even after this not all boards will cut straight but most should. If you have an overhead guide lite on the fixed saw [in a dark building] you can learn to guide the board but this is dangerous if you hold on too long. Don't give up, it can be made to work.

Brucer · December 07, 2018, 12:31:50 AM

My old edger had powered infeed and outfeed rollers. You had to guide the board by hand at the start, until the outfeed roller grabbed it. Otherwise there'd often be a slight hook at the end of the board.

Keeping the gap between the rollers consistent from one side to the other is a must. Mine had an adjustable spring on either side of the rollers to maintain downward pressure. The pressure had to be consistent from side to side as well.

I'd still run into trouble with pitchy boards. Sawdust would start to build up on the feed rollers (mainly in line with the saw blades) and this would cause unequal spacing and pressure from one side to the other.

I discovered that WD-40 and a wire brush did a pretty good job of cleaning up compressed sawdust.

strunk57 · December 07, 2018, 07:29:41 AM

Most the boards are covered in dust, that makes sense. The first board ran perfect. I did notice some build-up on the rollers. Now the question would be how to keep them from building up?

moodnacreek · December 07, 2018, 08:41:59 AM

When edging pine the sap sprays on everything and builds up on the [pipe] press rolls. I remember thinking that was a problem and cleaning it off. This is not practical. They real problem at that time was that the 2nd. out feed dead roll [on the outfeed table was out of square] and sometimes the board would not contact it and saw ok. When you are running the machine it is impossible to trouble shoot these little problems. This is why everything has to be measured out exactly to leave no doubt about alignment. Edgers can drive you nuts.

Mad Professor · December 07, 2018, 09:06:42 PM

I ran an edger in a commercial mill years ago.

It is important to get the board started true. But more of a problem, when cutting pine, was buildup of dust/pitch on the rollers. We had a hand pump sprayer w/diesel fuel in it, if we started getting curved boards, or when taking a break when the sawyer was sharpening the circle mill, we would spray down the rollers.

moodnacreek · December 08, 2018, 08:19:30 AM

It was only the press rolls that got the build up on my edger. The feed rolls, 4 shafts with 4" star wheels, don't get the pine build up but if any thing else gets caught in them the board will curve.

FarmingSawyer · March 01, 2020, 03:36:58 PM

I just finished getting a Tower 27" edger going. I reset the fore and aft fences to be parallel to the blade. When I use the infeed fence to guide a board with mostly straight edges I get a pretty straight board at the right dimension with clean edges.
But if I run a live edge board thru almost every one comes thru curved.

The edger was
Poorly set up at the mill I bought it from when I ran it there. I fixed most of the stuff except this. I'll go check everything for parallel and square now I've read this post.
Anyone have any other ideas why it's cutting curved or how to fix it?

moodnacreek · March 01, 2020, 07:24:38 PM

That wood outfeed table is no good in my experience. Just a whisker of friction to one corner of the board touching it and another banana. Steel rollers , say every 30" set in square with mandrel and level worked for me. If they are not perfect they are no better than the wood. Sure where a lot of those old Tower edgers.

FarmingSawyer · March 02, 2020, 12:52:14 AM

I was the tail Sawyer and edger man for a small mill out west. The edger we used there had a wooden outfeed table and it worked fine.

I did find that the in feed rolls, a couple of them, were out of sync. I made them all parallel. That helped A bit. Worse tho is the fact that the mandrel is 1/2 out from the live rolls. I tried to adjust it, but the bearing block holes and the holes in the frame are off enough that I'll have to enlarge the frame holes to get any movement.
These are newer bearings which replaced the Babbitt bearings.

moodnacreek · March 02, 2020, 07:55:32 AM

If the edger has enough grip between the feed and press rolls to hold the board straight most any table would work. Most edgers talked about here are light weight 2 saw board edgers with just enough grip to get the board through. A slight breeze will cause a problem.

FarmingSawyer · March 02, 2020, 08:16:42 AM

I don't have any experience with modern edgers but one of the reasons I love these old cast iron ones is the heft of the infeed and outfeed rolls. They actually leave a slight imprint in pine....

I think my issue mostly now is the mandrel being out of square. 1/2" over 27" is minimal which is why if I hold the board against the fence it comes out straight. But if I let go towards the end the blades pull the board to the outside. The effect gets worse the wider the board edged because the outboard, movable blade is at a significantly different angle to the fixed blade.

Not sure how I feel about enlarging a hole in the cast iron frame enough to allow the bearing to shift to parallel the saw shaft with the feed rolls.

kwaldron199 · March 02, 2020, 08:35:11 AM

Wood table is easy enough to fix.... Home Depot & Lowe's both carry Formica......Contact cement on both Formica and table top let both get tackie and then press and stick and you now have a slick surface at minimal thickness that it will take at least 185 degrees or higher to turn loose. You can cut the edges with a saw blade turned backwards or use a router with a following bearing on a straight edge adjacent to the edge of the table.

Roller presser on front or back rollers not being the same can cause similar problems. In addition front and rear tracking not being parallel to the cutting wheels could be another. One other problem that sometimes arises is a belt slipping on a pulley ever so slightly.

kw

moodnacreek · March 02, 2020, 07:42:09 PM

Quote from: FarmingSawyer on March 02, 2020, 08:16:42 AM
I don't have any experience with modern edgers but one of the reasons I love these old cast iron ones is the heft of the infeed and outfeed rolls. They actually leave a slight imprint in pine....

I think my issue mostly now is the mandrel being out of square. 1/2" over 27" is minimal which is why if I hold the board against the fence it comes out straight. But if I let go towards the end the blades pull the board to the outside. The effect gets worse the wider the board edged because the outboard, movable blade is at a significantly different angle to the fixed blade.

Not sure how I feel about enlarging a hole in the cast iron frame enough to allow the bearing to shift to parallel the saw shaft with the feed rolls.

I would do whatever it takes to square things up because even if it doesn't fix the problem it is 1 less thing to consider. To leave something out of alignment just adds to the confusion and edgers are very confusing.

Ron Wenrich · March 03, 2020, 10:35:29 AM

Usually, when you're using a fence for the straight edge, you're cutting with one saw. When you're cutting using 2 saws, is that when you have the problem? Seems you might have a problem with the teeth in one saw.

If you're running your shaft out of square by that amount, you're putting a lot of lead in those saws. Too much lead will pull your boards to the long side. Dull teeth will do the same thing.

If the rollers are worn, they'll pull to the long side. The long side will be traveling just a bit faster than the worn side.