Four-Side Planer Versus Moulder

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A discussion of the relative capabilities of four-side moulders and planers for straightening, smoothing, and cutting profiles. May 12, 2005

We are ready to get a four side planer and have convinced ourselves that the Martin T90 is the way to go. This machine has fixed heads and uses Tersa knives. Our jointer and planer currently have Tersa knives as well.

A moulder salesman is telling me that we if we set the moulder up as a dedicated planer, we should expect to get the same results as we would from a dedicated S4S machine. The three primary arguments on behalf of the moulder are initial cost, resale and flexibility of heads. The Martin is restricted to Tersa knives. The moulder can be set up with spiral knives.

Most of what we build are kitchen cabinets. We build our own doors and our product is primarily flush inset face frame. Except for the edges of the face frames, everything we would mould will also pass through a shaper or widebelt sander after passing through the moulder.

The moulder we are looking at is something along the lines of a Weinig quattromat. The most important thing to me is being able to straighten a stick. As I understand the Martin, you can raise the initial pressure feed roller and feed the stick in like you would do it on a jointer. The pressure roller engages on the back side of the cutterhead and the stick becomes straight. I am not interested in buying any machine if it won't give me some ability to straighten. I am not looking for miracles, but I would like to feed a 36 inch long board with a 3/8 inch bow and get some semblance of straight on the other end.

1) Can a moulder do any kind of straightening?
2) If a dedicated S4S planer and a moulder are somewhat equal in this respect, how influential should the ability to use spiral knives be?

Forum Responses
(Solid Wood Machining Forum)
From Dave Rankin, forum technical advisor:
Let me address one issue at a time. As for using spiral heads, you will get several benefits:
1) reduced horsepower requirements
2) reduced noise

3) in most cases, a better finish
4) in most cases, tools that last longer
5) with a spiral head you can change only the inserts that are dull; less expense.

As for the second issue, moulder or planer, only you can make that final decision. After working with several thousand shops that selected the moulder over a planer, I have this opinion: A moulder allows you to run S4S (up to the width of the moulder) as well as a full selection of profiles. Many cabinet shops have found that being able to produce moulding in quantity increases their overall business by more than the cost of the moulder. If you consider a good used moulder, you may find that you can get a better machine for the same or less money. If you need to run wider boards, a planer is the better option.

From contributor I:
I think I would be leaning towards the moulder. Depending on the machining capacity that you require, if a moulder can handle the size of the stock that you need to machine, it also offers the capability of producing mouldings. As for the straightening factor, increasing the pressure on the feed rollers won't exactly straighten the board on either machine. It will hold it straight as you feed it through, but when it comes out the back end, it will pop back. The moulder is definitely capable of producing straight S4S parts - it just needs to be set up properly. I suggest that you visit a couple of companies which are already using these types of machines for these purposes and get some feedback from them.

From contributor D:
We use our Quattromat to straighten (bottom and right), S4S, and mold all sorts of things. Light profiling (T&G, bevels, rabbets) is no problem with the side heads, and some fairly deep profiles can also be run on the top head. Weinig (and the others) has molders with long infeed beds for bottom and right straightening, as well as 5 or more heads for more intensive molding.

From contributor J:
1) The moulder's ability to straighten is in a rebate cutter located on the inside of the 1st bottom head. It puts a small reference into the bottom of the board that rides on a small fixed fence leading to the 1st right head. This keeps any side bend in the board from working into the right head. That is straightening. The ability to raise the pressure roller in front of the first bottom head is for flattening a board, or similar to a single pass over a jointer. This feature is also standard on moulders.

2) The spiral head is a nice feature, but not absolutely necessary.

From contributor A:
I have great luck flattening a board with the moulder with the adjusting infeed table. If it's really bowed, take a little of the bottom and hog most off the top. Proper stress relief does wonders.

From contributor S:
Let me also say that the moulder is a great way to go. I retail hardwood lumber and a lot of it goes through our moulder to S4S it. I have had great luck with our Weinig Quattromat. You can easily take a piece of 8/4 that has a 3/8 twist in it and get a perfect piece of stock in one pass. We save so much time not having to joint and then plane by using our molder for larger quantity stock runs. The only drawback is with the 9" width limit and the time to reset if running multiple or random widths. As for the spiral, we have just installed a spiral head on our planer and love it.

From contributor G:
Seems to me that a straight line rip saw would put a perfectly straight edge on the lumber. Then you could cut the strips to width using the fence. Most of the rip saws will make a glue line edge up to at least 8 feet.

From contributor C:
The T90 four side planer-moulder is a unique machine compared to other moulders and four siders on the market. The fixed Tersa heads with insert slots for moulding cutters is the big difference from other machines. As a S4S machine, it has no equal quick, accurate numeric setting, quick knife change, effortless movement of the infeed table and edging fence, the floating side head for running random width boards into panel glue up material and as you mention, the fine tuning of the pressure rollers for straightening. Another good feature is the ability to take off only .5mm with the top head without leaving marks from the steel rollers. Building only cabinets, you will probably never use the full 6X10 planing capacity like we do for architectural doors and millwork.

As a moulder, the T90 in 4 head version has some limitations. The 12mm depth of moulding cut limits you from big crowns and such, and you cannot grind your own knives, they have to come from Martin. Takes a couple weeks. And no bottom cut with the 4 head version. The one thing I really like about the insert moulding knives is the quick setup. One pattern we run a lot is T&G beadboard. Using 3 heads, it's a 6 minute setup and less to break it down. We use ours a lot for T&G paneling. Rebates, odd short runs of mouldings for cabinets and doors. Cabinet light rail is one example. Sometimes we run only 50 feet. If you want to run a lot of moulding, you would be better off with a Weinig type machine. The Quatromat is a lighter, smaller footprint, less expensive machine and might be more cost effective in a cabinet-only shop. Whatever machine you decide on, your times for solid wood processing will drop dramatically.

From the original questioner:
Thanks for all the responses. I really appreciate your thoughtful input. I am going to go, sticks in hand, tour both types of machine. My primary objective will be to evaluate for straightosity. I will also be on the lookout for the roller marks mentioned when removing .5mm.