Aligning an Older-Model 4-Head Push Through Moulder
I have replaced the square heads with round heads. There are two devices that hold the stock to the fence - a lighter, spring loaded hold-down under the feed rollers, and spring loaded curved wood block right in front of the first side cutter.
Even by keeping the stock feed end-to-end nice and tight I get snipe on first 3-4 inches and the last 6-8 inches. I've tried more and less tension on the hold-downs but haven't figured it out yet. The cutters are offset and most of the snipe, but not all, is from the first, outside cutter. Any suggestions?
Also, for those of you who are small like me, how are you end matching your flooring stock? I know a lot of you don't bother, but I have gotten a large (for me) wholesale customer who requires it. I was going to buy two molding heads for one of the shapers, and built a cross slide sled to mill the ends. Any better ideas?
From contributor B:
From your post it sounds like there are a couple of things you could check out. First, take a straight edge and check that all the fences after the right spindle are parallel. It sounds like something is off there. Second, make sure the lowest point of the knife just barely touches the fence after the right spindle. Put the infeed fence at zero position and all the fences should line up. If not, the infeed fence may be out of parallel as well. These are just a few basic things to check that are overlooked quite often.
From contributor C:
That a little unusual. A couple of things Iím thinking are: your inside vertical spindle is not set perfectly flush with the static fence right behind it. Next, I would check your inside static fences before and after your inside vertical spindle to see if they are parallel. That could explain why your pressure devices are able to move the wood that much. Last, is your wood ripped fairly straight? Bowed or undimensioned rough lumber can cause this. I hope this gives you a few things to check. About the end matching thing, I think a tenoner or double end tenoner is used for that for heavy production. Iím sure the other guys will correct me if Iím wrong.
From contributor D:
You are experiencing what is known as pistol grip. In flooring this can result in side snipes or variation in dimension. A simple way to look at the wood to determine how much pistol gripping that you are getting is to hold the board on the tailing end and see how much "bow" is at the end. On a push type moulder, pistol gripping or snipe can come from several things. I agree with earlier posts about the fence and head reference, but what needs to be explained is that on most push feed moulders the fence after the back side head is designed to move in and out. The fixed fence is typically the fence before the head.
When I set up a push moulder, I preset the movable fence after the side head to about 1/2 of the oversize in width of the raw stock. I then check it for parallel with the infeed fence using a straight edge and filler gages. The side pressures on the outside of the machine need to be parallel and controlling of the work piece.
If you are still getting snipe, then check the rollers or chain in the infeed table and make sure that they are level to the tables. If these are out they can cause the work piece to lose control as it enters or exits the machine. There are others things that can cause the problem, but the above listed ones and the ones from the other posts should take care of most snipe and grips.
From contributor E:
These guys are heading you in the right direction. When aligning a push feed moulder you start with the right side or inside fence after the top head. You need to make certain that the fence is exactly 90 degrees to your top head spindle. Using a piece of flat bar standing on edge against the back side of your top head spindle set a machinist square against it then see if the fence is 90 degrees to it. Now that youíve squared this fence you square every other fence to this fence. Youíve now aligned your fences. Next you have to align your feed rolls. Use a 4' straight, edge lay a piece of 5/32"flat bar, or planer steel, across your infeed bed parallel to your first lower feed roll. Lay your 4' straight on top of your flat bar across both rolls leading to your top spindle. The end of your straight closes to your top spindle should lie on the bed plate directly under the top head chip breaker. Now raise your lower feed rolls up till they just make contact with your 4' straight edge. Unless you have two 4' straight edges, you will have to slide the straight edge back and forth to get both ends of your rolls set parallel to the bed.
Now that youíve done this, there is one more adjustment. Now using a .005 feeler gauge, lower both feed rolls on the end closest to the operator. This gives you lead towards your fence. Push feed moulders are built with an 1/8" lead per foot in the feed works, but this makes the wood suck up to the fence line, because it wants to ride towards the tight side. This will cure your problem.
From contributor F:
Just one more thing to consider since most push through molders are of some vintage is worn bed plates. This can also create some difficult to diagnose issues.
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