Moulder Fence Adjustment Issues

Woodworkers troubleshoot a problem with wood drifting away from a moulder's fence during operation. February 10, 2009

We have a one year old Weinig Unimat Gold Six Head Moulder. We have experienced the wood travelling away from the fence in the past and just recently my moulder operator noticed something interesting: if you raise up the two top heads with their chip breakers and pressure shoes the wood still comes away from the fence. This was done with only the feed system running - the cutter heads were not on.

Is this simply because of wear on the urethane rollers? We were told by our Weinig tech that the machine comes factory set with a 3 degree cant on the feed roller shafts. This is supposed to keep the wood tight to the fence. Has anyone ever adjusted this cant (or angle) to make it more so that it would keep the wood tighter to the fence in a case like this? Any feedback would be appreciated.

Forum Responses
(Architectural Woodworking Forum)
From contributor B:
If you are using all urethane rollers try putting all steel back on. That will tell you right away. Also try less pressure on the feed wheels. Three degrees should be more than enough set to drive the stock to the fence. As I said in an earlier post, beefing up the outboard fences is not a bad thing to do. This helps when boards are not straight, and etc. I would start looking for defects if all else fails.

From contributor M:
I followed the question and thought maybe you had the problem solved. If you're talking about the wood moving away from the fence after going under the top heads, you should have an adjustment that sets an outboard fence that holds it tight against the right side fences. I thought for sure when I read the question that you had your steel feed wheels on backwards. Are you sure they are on the right way? I'm sure you've checked, but unless it's your reference engraver that's messed up, then it can't be anything else. I guess there is the possibility that somehow when your moulder was built that the three degrees of cant didn't get built in, but I think that's remote. Sorry, wish I could be more helpful, but I don't know what else it can be. Confirm your feed wheels are on the right way.

From the original questioner:
We have confirmed that the steel feed rollers are on correctly. We have also confirmed that there is a cant on the shafts (although I have not measured them to know for sure they are three degrees).

What my moulder operator did recently is he raised to two top head with the chip breakers and pressure shoes and with the outfeed fence being pulled back sent a piece of stock through with only the feed system; all of the heads were turned off. He wanted to see if the wheels would keep the stock towards the fence in and of themselves with the heads and their cutting resistance being out of the equation.

What he discovered was that the wheels pushed the wood away from the main fence; I do believe it was mainly the urethane rollers that did this though. I believe the steel rollers kept it towards the fence but once past them the urethane rollers pushed it away from the fence.

So, this would explain why we have to fight with the stock so much to keep it tight to the fence while jogging the wood through. We have designed and built a better out-feed fence. It is working well but still we have to fight to get that wood against the main fence.

Could it be that the urethane rollers are worn unevenly and this is causing them to push the wood outward rather than inward like they should? Can they be re-shaded if this is the case?

From contributor M:
Urethane rollers can be recoated, but before I did that, I would take a look at the rollers that have the replaceable tires. Weinig has them as well as Western Roller.

As for the stock pulling away from the main fence as it goes under the top heads, that happens on mine also when I run stock with the side heads backed off and I'm using the moulder to pre-surface some stock before the final run, but it's not extreme. As I said, with the outboard fence set to the correct axial dimension it hasn't been an issue for me. The only issue I've had is when it's been set too tight and stock gets hung up under the top head.

From contributor B:
Do you have outfeed rollers in the table below the urethane rollers? If so, try putting them and the urethane rollers on backwards and send the board through again with no heads running. This should tell you if the rollers are worn. Since those rollers compress they tend to push in all directions. We hold the board against the fence as it comes out of the top head and then set the outfeed fence.

Also, what is your outfeed table like? Once the board is past the steel rollers there is more of the board out of the moulder than in it. A canted outfeed table can greatly affect where the board goes. We always try to set the last urethane rollers on the flat section and a little to the outside where the profile starts so the wheel is pushing back toward the fixed fence.

From contributor R:
You mentioned you had "aligned" your fences with a mason's string - not a good idea. If I had to guess your fences are misaligned. You also mentioned you had this problem with wide boards only. The pressure elements will not spring a wide board hard against the inside fences if it is not straightlined ripped going into the machine. A molder has limitations regarding jointing stock and you cannot take for granted the right spindle will true the edge. Furthermore, the stock will always want to move away from the inside fence as it exits the top cutterheadand and is pulled out by the rubber rollers. That’s the nature of the beast and also what that outside fence is for. I don't mean to be unkind but you would do well to get someone in that knows the machine to troubleshoot this issue for you and possibly provide some additional training as well.

From Gene Wengert, forum technical advisor:
I second contributor B's comment about the infeed and outfeed tables if the pieces are long. It is also possible that the problem is being accentuated by stress in the wood (also called casehardening). Take a blank and rip it in half lengthwise (width) and then put the two pieces back together. There should be no gap. If there is a gap, we have stress that will result in warp when machining.

From the original questioner:
To contributor R: yes, we did attempt to align the fences with a mason's line; we used this as it was the best thing we felt we had. At that time we talked first with Weinig in NC and they told us to check our electrical channel at the back/bottom of the moulder. He said that usually the moulder will come with a long straight edge that is used for such alignments.

Well, we looked but it was not there; so upon calling Weinig back they expressed that maybe because it is a lower cost moulder then I guess it doesn't come with it. So, when we asked what they cost he told me $700.00. Wow! That sounded like a lot of money. When we attempted to straighten with the mason's line it did help tremendously in keeping the wood against the fence. We have since had to do that once more.

Would you recommend we look for a good straight edge and check it that way? Also, I am open to the training. My father has suggested I travel to NC to take Weinig's One week Grinding/Moulder course. Perhaps I do feel as though we have learned a tremendous amount in our first year through hands on and working with Weinig tech support on the phone. Do you recommend Weinig's school?

From contributor M:
By all means go to the Weinig school. The one week course was included in the price of my moulder and hopefully the same holds true with yours. It will help you get the most out of your machine.

From contributor I:
If you go to a good flooring supply house you can buy a decent straight edge used for vinyl flooring. It is imperative that all the inside fences are aligned. This may also sound basic but is your operator getting the first side head aligned properly to the fence. I would examine the board for snipe on either the leading or tailing edge which will indicate that setting is not correct. I would also look at the reference graver for alignment and be sure you are removing some material with the first side head to joint the board.

Is the stock going in to the machine straight? You can't force a wide board straight if you have exceeded the amount of jointing ability of the first side head, it has to be ripped straight. You need to also examine the chip breakers that they are level across, are working equally and not gummed up, and that the pressure shoe is also parallel to the bed.

From contributor J:
We have had three Weinigs and they all do that. Weinig sells a beefed up outside fence that works great. I did the same test with just the feed going and got the same results. I also recommend the training in NC. It will help with future problems.

I think that $700.00 straight edge you can get most of that money back when you send it back to them. I’m not sure if they still do that but you might want to check with that. I talked to a tech in person and he told me it was the knives cutting that pushed the wood away. That’s not the case when just the feed is running.

From contributor L:
For a great straight edge take the in-feed fence off the machine and use it. You might check the last bedplate and make sure it and the shim are clean. If it is even slightly tilted it will cause problems. I'm inclined to believe that you have an alignment problem between all the fences and the reference engraver or the setting method for the right head. If you’ve ever tried to get a perfectly straight board from a jointer with the tables not parallel and/or the out feed table set a little high the same problem exists there. Very small variances have a big affect.

From the original questioner:
Thanks everyone for some great advice. I will follow up on a good straight edge as I also agree that it is critical to have the fences lined up perfectly.

In regards to the right head; the way we set that is with our small straight edge and make sure that the outfeed fence on the side is perfectly lined up with the outer cutting radius of the knive. This is something we learned on our own. Our Weinig tech had us originally set it via the measuring stand's reference radial measurement. We discovered though that it is more accurate using the straight edge. We also do the same thing on the last bottom head in setting it to the last table plate. This is the same method I have used for years in setting up our jointer knives to the outfeed table.

Everyone has contributed some great points. I wanted to comment on the outfeed fence; the one that came with our machine was of a very poor design in my opinion. It gave us problems over and over. A few weeks back it was actually destroyed. You see, we were running a top mount crown and by its design the moulding tends to exit the machine and head then head on an angle once it clear the outfeed fence. Well, it pushed the outfeed fence out just a little tiny bit and consequently it caused the outfeed fence at the beginning to be closer to the main fence by just a bit. When the next piece of wood went through it pushed the outfeed fence right up into our second top head – yes while it was running. It was a costly accident. The head is fine but the knives (as well as that silly outfeed fence) were destroyed.

So, I spent a lot of hours since then designing and building a much more effective outfeed fence. It is working great!

From contributor I:
We run a Weinig Hydromat and also two SCMI supersets, and to be honest the entire ouside fence system from start to finish pales in comparison to the SCMI. We suffered the same fate as you on the outfeed and have also had other castings blow apart just prior to the side head which is also of very weak design.

From contributor P:
That’s exactly what it sounds like to me. The rubber wheels are to worn on the inside and there is more rubber on the outside. Try to turn the wheels around and see if that helps it should pull the wood tight against the fence.

The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).

Comment from contributor F:
I have had both infeed and outfeed tracking issues. I have only been at this stuff for 25 years, and Weinig moulders have me learning every day. Fences must be aligned correctly without question, the same for infeed and outfeed tables. You mentioned that your operator had chip breakers and pressure bars down while running a piece through. Did you try using only the infeed rolls? Did you keep the chip breakers and pressure bars off the wood? I have the bearings wear out on the outside of the bottom outfeed roll. This caused a problem as you have described. Also you can lift the feed rolls past the first top head and only use the infeed drive rolls to help pin point where the problem is. String line, no, straight edge, yes. Chip breakers/hold downs and pressure shoes need to be parallel with the bed plates.

Comment from contributor T:
One thing that should be checked, when all else fails, is the bolts attaching the drive axial casting to the main feed beam. I have seen these bolts work loose. Then as you let the feed beam down you will have some negative camber that will pull the wood away from the fence. Also, badly worn axle bushings, front and back, will cause this.