Multiple Dowel Moulders
Dedicated machinery to make more than one dowel at a time is an unusual application. Here's a detailed thread on the ins and outs of it. July 3, 2008
Question
I would like to produce multiple dowels on a moulder. We own a couple of Diehl feed-through moulders but I'm certain the setup would be fairly time consuming. I would really like a dedicated moulder that is specifically designed for making multiple dowels. The top and bottom horizontal heads are apparently located closer together than a conventional feed through moulder. Does anyone know of a company that makes these machines? I'm still open to the idea of using my Diehl feed through moulder. Any suggestions as far as tooling, custom pressure shoe and guides are concerned are appreciated. My dowel size is 7/8" and my production needs are beyond the scope of a hawker.
Forum Responses
(Solid Wood Machining Forum)
From contributor D:
There are about 10 machines at Ex-Factory.
From the original questioner:
Thanks, but I'm not looking for a machine to run singles. I'm looking for a dedicated moulder that will make multiple dowels in one pass. All the machines listed at Ex-Factory are rotary type dowel machines designed to cut one dowel at a time.
From contributor D:
The reason I posted what I did is this is the way the world makes dowels. Not to say that you can't change that, but it is not as easy as buying a machine, since none exist to do what you want to do.
Dowels traditionally are made from scrap and have a high waste factor anyway, so the industry just doesn't think in terms of sending prime boards through a molder to make little sticks. There are big problems with hold-downs and tooling on a molder just to run one dowel. The problems multiply with more than one dowel (as one that ran closet rod in 8,000l/f quantities with a four head set-up). The setups and tooling will be very expensive, enough so that you would need to have a 5 head machine running only that setup to make it work.
From contributor C:
I think you are talking about a side matcher. Setting up a molder or matcher for dowel production is not that far out of reach. I haven't seen a factory setup in years though. I would see what haskomachines.com could do for you. Custom bed plates and hold downs are the major things to consider. As far as tooling, a milled to pattern setup would be my first choice, but I am old school.
From David Rankin, forum technical advisor:
There are a few dedicated dowel machines that I have worked on over the years. Most have been Weinig moulders that you designed slightly differently for the dowel production. If you are looking to run 1/2" (12mm) to 1-1/2" (38mm) dowels, just about any moulder can do this. I generally split the dowel cut between the top and bottom heads and use a custom pressure shoe to control the multiple pieces. You are required to use an anti-kickback device when splitting. As for locating a used multiple dowel machine, I have not seen a used one in the last couple of years.
From contributor K:
Wisconsin Knife Works used to make that sort of thing - mtp heads, bedplates, etc. We used to do it with ground knives, but your tool room has to be top notch. Also, what is multiple - 3? 4? 10? I don't think we ever went over 4. In a lot of ways multiples are easier, more flat bearing on the table, etc. Those hawkers claim to run at 150 per min and up. That's a god-awful lot of dowels. How much do you plan on making? Also, I don't know if I've ever seen moulder run dowels that didn't have some mis-registration, out of round, etc. Here's a company that says they make mtps for your purpose. Custom cutting tools. I don't know their contact info but you can Google them.
From contributor D:
While I stated that it is rare to see anyone running dowels in multiples, pencils are the most notable exception. 8 to 10 wide, at 200l/f per min coming out of a very specialized machine. 10 pcs x 200' x 60 mins x 8 hrs = 960,000 l/f a shift. At 7" long, that's 1,645,714 pencils per shift.
From contributor R:
Weinig does make a special dowel machine. It's been years since I have seen one, but they do make it.
Some concerns about splitting over 3/4" dowels. The apex of any circle is right at 90 degrees, therefore you have regrinding issues and burning issues unless you're using insert or braised on carbide knives that are face ground. Insert tooling would be my choice. The knives should have side clearance. If face ground these will distort the profile a bit each time it is face ground. If you're grinding your own in high speed steel, you will have to take at least 1/32" to get the knives back. Burning and heating up the tools will be an issue for sure.
The next thing that comes to mind is the amount your bedplates will be open to incorporate the cutting circle. The bigger the dowel, the more your bedplates must open. I believe you're inviting snipe on the pieces unless you have a special bedplate to receive the dowels as well as a special pressure shoe to hold down the product.
As Dr. Dave mentioned, anti-kickback for sure. Not knots in any of the work pieces or you will have damage to your equipment. It can be done, but a lot of thought and money must go into this to make sure you're safe and you're getting the best product.
From contributor D:
When running rounds on a 5 head Weinig, as singles, we put a 100 degree arc pair of knives on each head. This eliminated the problem of regrinds, made all four knives/heads identical, and would result in a very high quality round with a little care. The cut to each head was balanced, and the material was relatively easy to hold. In my opinion, the only way to make rounds.
From contributor R:
I would agree with contributor D. Using 4 heads - right, left, top and bottom - to make a single round would be the way to do it. This way it cuts down on your cutting circles and the blend areas are not noticeable. This is the way I design all rounds over 3/4" in diameter. But the questioner wants to run multiples. I agree again with contributor D - taking large boards to make small dowels seems kind of wasteful with all those rips being produced in this industry. Oh well, I guess you have large numbers to justify going this route.
From contributor C:
It's really not that hard to set up once you have all the pieces in place. I ran 1.5" diameter 10' dowels 4 at a time out of hard maple a few years ago. You do need to make a dedicated set of pressures and bed plates. I simply made some UHMW inserts that screwed into the removable plates on my machine. If I did it again, I would try blue nylon, even slicker.
I don't grind my own knives (yet), so I'm not fluent in knife geometry. For the size I was making and the material, it was recommended I use a stronger knife stock - T2 comes to mind but I would have to check. I'm sure the previous posters can explain in much better detail, but the geometry of the knife is not just a circle, there has to be some elongation of the profile to account for how it passes through the material. I don't think carbide would be a good idea, but I'll leave that to those that know for sure.
I ran mine using just the top and bottom head. This is I'm sure common sense, but check your pressures. I got half a revolution out of my first set of top knives because I didn't double check the pressures, and those knives are long. Nothing like shrapnel coming out of the moulder...
Feeding is also an issue. Once they get past the bottom or last head, there are 4 or however many pieces, and each one needs to be fed somehow. My machine is older, so perhaps this isn't an issue for newer equipment, but I had to make extensions for my feed wheel shafts to get enough wheels across the table to make sure all the dowels were being fed. Dedicated, profiled wheels would be on my list as well if I do dowels again.
I would think in particular that if you are running an axial constant system, it might take an extra hour to set up to run dowels once you have it figured out. It takes me about 2 hours to change over all that and get it set, non-jointed or axial constant, and no DRO's. I'm not a huge production shop, so that isn't an issue for me.
Hope some of this was helpful, and thanks to the regulars for all the knowledge they share.
From the original questioner:
Thanks for the responses! There are a number of reasons I would like to run multiples instead of singles. My product requires a moisture content of 10-12%. Most edgings come from material dried to 6-8%, which gives me a supply problem. Also, it's very labor intensive ripping edge strips since each strip must be handled one at a time and edging strips have a high waste factor. My project is also ongoing so I must consider my long term raw material supply.
Contributor C, is it really necessary to have a dedicated bed plate for this application? I was thinking of using a custom pressure plate that extended from my top horizontal cut to the end of the moulder, providing a track for the dowels to travel. I would essentially be using a feed through moulder as a push feed since I wouldn't be using the last outfeed rollers. The trailing dowels would provide feed through pressure as long as I was feeding material back to back.
Contributor R pointed out something that's been a concern of mine. A perfect round will give me a 90% cut at the apex. Should my milled to pattern head have a 5% offset at this point to keep my tooling from overheating and causing knife failure?
From contributor R:
A 5 degree flare tangent to the circle will put the circle out by .002" per half per side. So on the whole circle .004" per side x 2 = .008" out of round. That's the math; the rest depends on you as a manufacturer, your customers, and your quality standards. The hhs tooling will still tend to get hot and lose some temper depending on how long you let it run between sharpenings.
From contributor C:
If you can get a continuous pressure on your machine, I would think that should work. It would be hard to do on my machine, as it's about 3 feet from the last bottom head to the end of the machine. I would also be concerned about getting the "troughs" to run parallel to the fence. And my first moulder was a push-feed - I really wouldn't like to go back to that, but I understand what you are trying to do.
From contributor V:
We run closet pole (1-5/16 full round) on an old Woods 132 five head. We run 2, 3 or 5 at a time. We cut half the profile with the top profile head and finish with the bottom. These heads are about 11" apart and a lot more forgiving if your material isn't perfectly straight. We use a maple hold-down, vee grooved on a table saw to match the pattern. In softwood we run okay with 3/32 kerf. These old machines are cheap but require a fair amount of floor space.
From the original questioner:
We purchased a multiple dowel moulder made by Northtech. It's basically a two head moulder. Unlike a normal feed through moulder, the infeed bedplate extends all the way up to the bottom head in one piece. It makes it very easy to adjust how much I take off with the bottom head. So far we're extremely happy with our purchase.
The comments below were added after this Forum discussion was archived as a Knowledge Base article (add your comment).
Comment from contributor L:
I manufacture drumstick and police baton blanks and my desired moisture content is 10-12% also. I use hickory for all of my production. Something I have done with material I purchased at 6-8% is stacked it on dried stacking strips under an open shed for a few weeks. The wood will naturally pick up moisture in the air and come back to a neutral point of 10-12%. After you try this a few times monitoring it closely you should be able to achieve the same results. Do some research on air drying procedures - this could potentially help your material supply issues.
