Troubleshooting Moulder Jams

Strategies for dealing with the problem when boards get stuck in the moulder. April 24, 2009

We purchased a Wienig Profimat P23E 5 Head Moulder a couple months ago which has been beat its whole life. We replaced all the knives, urethaned the outfeed wheels, the tension wheels on the side, and other minor components. The feed the wheels are good and sharp. When running new lumber through it, the machine works fine. We make a lot of flooring from used lumber from a grainary mill, usually 1x6's. When running the used lumber, the machine jams every few boards. We’ve tried yanking it through, hitting it with a sledge hammer and just about everything else we can think of! Any ideas or suggestions?

Forum Responses
(Architectural Woodworking Forum)
From contributor E:
You are using Waxilit on your tables aren't you? If you're able to run new lumber removing equal amounts compared to the reclaimed lumber and have no jams, then try some good bed lubricant. If you are using Waxilit already, then I don't know what could be causing the problem.

From contributor I:
Please, please, don't hit the boards with a hammer, another board, 4 x4 sticker, or anything for that matter. What’s going to happen is there will be the one time something is truly jammed and you will push metal to metal. I had an operator discover this for me, and it cost the entire outside chip breaker casting on our Weinig as it was forced into the head. Double check all fences and alignment. You may also check the rear hold down because although it may feel adjusted right they will gum up and not move freely. There is a fine balance with down pressure on all the adjustments, too little is not good, but too much doesn’t work either. There seems to be a common misunderstanding, if the wood is not feeding it needs more pressure, wrong.

From contributor J:
Try this easy test. Take ten reclaimed boards, plane and rip them 1/4 inch oversized. Set your table on 2 and your fence on 3 and run them. This should determine if an inconsistency in width and thickness is contributing to you problem. I would also compare the moisture content between the new lumber and the reclaimed. Sometimes a higher MC will not feed as good as the dryer wood.

From contributor A:
Waxlit is good suggestion as well as experimenting with different air PSI settings for your feed rollers. If the wood is rough, heavily cupped and/or different thicknesses it can help massively to plane one side before putting through the moulder. Put the planed side up so you get better feed traction.

From contributor D:
I bought a brand new Weinig Unimat Gold 6 Head moulder one year ago. It is a good machine but we often have issues with wood sticking going through. It seems to me that a common challenge to running a moulder is having wood sticking as it goes through. It is challenging to find the fine line between having enough pressure on your chip-breakers and pressure shoes so as to have no chatter marks on your boards and having too much pressure that it causes the boards to stick as they go through.

I was at the Weinig Expo in 2007 in Mooresville and I observed that even the Weinig techs were having the same problem at the Michael Weinig Center with boards sticking. I believe it is the nature of the beast.

One thing that I am a firm believer of is waxing the bed of the moulder first before any run with a good quality paste wax like Johnson's paste wax. This will help tremendously when jogging your first few pieces through to set everything up.

Remember: cause and effect. If the boards are getting stuck there is definitely a cause. Sometimes it is easy to get frustrated after trying just about everything but cause and effect still remains.

From contributor S:
Along with all of the other good suggestions I would look at MC and the type of wood. Teak will not go through a moulder well with HSS knives and other woods can cause similar problems. I assume you do not have trouble with other 1 x 6 material but are you taking the same amount of material off the old wood? If you are taking more off the top then you need to adjust your chip breaker for that. If the material is not straight lined your will have trouble feeding. If a board does get stuck, stop the machine and loosen one hold-down, chip breaker, and feed wheel at a time to see which one had all the tension. Then you will have an area to look at for the cause.

From contributor A:
Feed rollers always feel sharp, I would suggest adding two new ones after the first bottom. With the reclaimed wood being harder you might jog the first piece through and set the fences light. Add extra air pressure to the steel feed rollers so it cuts into the harder wood.

From the original questioner:
Thanks for all the great tips and pieces of advice! We fine tuned all the fences and table panels, played around with the hold downs some more, and finally, ordered some Waxlit which is I believe is now the key to running reclaimed lumber! In four hours we ran 5000 feet! Much better the maybe 2000 we were getting earlier!

From contributor W:
Even if the steel wheels "feel" sharp, you might sharpen them anyway. I did and it really helped on hard woods. This lets you get more bite with less pressure. Sure can chew up some pine if it gets stuck, though. I used a Tool and Cutter grinder, but a profile grinder might work with a small wheel.