Question
I am planning on building a single head (to start) bottom cutting molder using a Weinig 9 1/8" cutterhead and between a 5 and 10 hp motor. I have full CAD capabilities, so all parts can be sent off to the steel laser cutters to be cut out of 3/8 plate, all the welding equipment I need and basic machining capabilities (lathe and milling machine).
The concept is easy but there is little literature available to leapfrog off of. My total cost is hopefully (excluding knives) about $1000, because I already have the feeder, and the motor is going to come in used. I would love to get an old real molder but when you buy used, you buy "restoration".
One main reason I would like to build this machine is that another specialized woodworker (radius work) has a William Hussey molder and he *hates* straight runs. If I could cut the speed of cutting moldings in half, I would have $1000 a week in profit alone. Not bad for a minor investment. I would love to get a Real Molder, but cost and long term goals don't propel me in that direction.
Forum Responses
My company is always trying to re-invent something because the concept seems so simple. It usually costs us twice as much in the long run or we get a lot less than we wanted for what we spent versus buying. Nothing wrong with re-inventing the wheel, but it's going to cost valuable time which could usually be better spent in more productive ways.
A moulder looks simple in principle, but the fact is that a moulder has literally hundreds of small parts that must be machined with great accuracy. Mattison once had a photo of all of the parts for a 276 spread out on the floor. It was a sight to behold. I would love to see the same photo on a six-head Weinig.
If you only want one head, perhaps you should look at the Mereen-Johnson Versa Moulder.
The fact that you have the insight to design and try to implement something of this nature says you're sharp, but imagine what would happen if there was something that you didn't take into account and 60 pounds of tool steel, spinning at some-odd thousand RPM's, suddenly made its own decision. Bad scene to be wrapped up in.
There was a mention above about the Versa moulder. Good machine for the small stuff you're talking about.
My concept is to have a Weinig head on a drive shaft with bearings on both ends of the shaft so there is support across the head. The head is horizontal to the bed and a stock feeder propels the material across the cutterhead. The replaceable infeed bed acts as the chipbreaker.
So basically, I want to turn a shaper on edge but have the capacity to run larger knives with more power. The shaper is a simple concept and I want to keep it that way. I don't want to reinvent the wheel; I just want to make something work better but bigger.
I am not quite sure what that means.
When you say "head", do you mean that device in which knives are mounted and which is then mounted on a spindle or shaft, or are you referring to the entire assembled shaft with its yoke and bearings? What RPM do you propose?
RPM would be whatever would be correct. I am thinking about 20,000. *Just kidding!* If I end up with a three phase motor, I very well may put a speed control on it so I can increase/decrease the cutterhead speed as needed.
I can use a forge, an anvil, a hammer, and a chunk of rebar and make nails. I can also drive to Home Depot.
Don't get me wrong - I am the first person to try to think of a better way and would encourage you to continue to do so... but not so much with this.
All I have is a CAD drawing that basically only makes sense to me, so it is difficult to describe the thing, but it is as simple as it gets. The cutterhead is in the bed and raises and lowers on a locking pivot bar. Alignment would/should happen once. Once the head is aligned parallel to the bed, that is all there is to align. The head raises and lowers using a 3/4" threaded rod. The motor and head are fixed to the same framework. The bed of the beast would be a multiply plywood for wear and ease of replacement.
I think it was a cabinetmaker named Bill Biesmeyer (?) who brought us the standard rip fence on every new tablesaw on the market.
Take a look at the website for Unique Machines. You can buy a similar arbor and mandrill already made up. The rest is just limit switches, air pistons and thomson linear bearings.
These guys are probably right that you could make more money building cabinets. If I had enough money, I would probably build machinery as a hobby. I'd say go for it.
If one has a dramatically better idea, as with the two that you mentioned, then one has a good reason to build the machine. Without a really different idea, one is wasting money and valuable time from the core business. Even with a good idea and the belief that it is reasonably doable, the project can become expensive beyond your projections. I have just had a nine-year, million dollar lesson on the subject with our vision scanning project.
By keeping the design as simple as possible, with one moving part other than the cutter head, there is virtually nothing to adjust. The trick is going to be making sure all the plate steel parts are designed right to start with, as it is designed to simply bolt together with welding to lock everything together. I very well may have my brother actually take all my CAD designed parts and "assemble" them using a 3D graphics program, which would allow me to see where all the pieces would fit and/or hit. As I just typed this, I realize *that* is a brilliant idea and is going to be a major factor in keeping this thing on track with no design flaws. I will post a link when he is done so you can view the magical one-headed, ill-advised-against bottom head molder.
It seems this is something you are not going to shy away from, so let me lend a few tips:
1) Employ some form of anti-kick device just to make sure your work piece stays on the forward path to success and not the backward path to your groin. Whether it's just a feather board or maybe some ground teeth as used in a ripsaw, just use something.
2) Bottom head profiling is a pain, as is evidenced in the old Diehls and Madisons. You are going to want to "shoe" the bottom to get the most out of your work piece with the least amount of snipe. To do this, run a piece of the profile and cut a chunk out of the best piece about 6" long. Spray it with Pam or some other cooking spray. Take small slats and build a box around it that rims about 1/4" above the top of the profile. Fill that box with Bondo, the car body filler. Once dry, this can be glued to the deck with rubber cement (rubber cement will hold good but is also easily removed).
This should give you at least some measure of control against rolling or any other snipe-related mishap.
3) Finally, I'm not sure what type of design you're using, but make sure you incorporate some hefty plating around that head and on the dust hood. If something bad happens with that head or knife, just try to make sure it's a little "bulletproof."
A square tube weldment is fine, but after welding you'll need to stress relieve it, either thermally or vibratory. If not, when you start machining it will move, as there are internal stresses induced during welding. Welded structures do not dampen vibration like cast iron, plus they like to build up nasty harmonics. A simple way to deal with it would be to fill the tubes with grout.
I would be very picky on the design of the arbor that holds the knife head. The bearing housings/bores have to be perfectly aligned or premature bearing failure will occur. Overheating can cause arbor growth, which can push on the frame and throw all your other tolerances out. Self-aligning bearings or a floating bearing are a thought.
If you're raising the head with a threaded rod, what fixes the head assembly position, this must be dead solid. Do not assume the rod will suffice, as the thread and nut will have axial play. Use an acme rod for smoother action or even a ball screw.
I would be sure the cutter head/lift assembly could never "dig" into the work. With that much horsepower, if a knife grabbed, it could pull the entire arbor/head assembly into the work. That would be really ugly. I would turn the arbor from 4140 or 4340 stl and have it heat treated for safety and rigidity.
With that said, you can see the costs have already started to rise. Those are just some of the details that should be addressed. There are obviously more. If you are prepared, you should succeed.
I would try to fashion your single spindle moulder, if possible, after the Mikron, Steggher, or MJ, being top cutting. I know this presents a lot more design work and thought, but the end product would be much more useful. Bottom profiling generally is a one time shot. You get into radius work or even heavy profiling, the ability to take two or three passes is huge.
I actually had in my possession a 12" 2 knife babbit bearing Northfield jointer that a craftsman from the past had used as a moulder. There where hundreds of knives that had been hand-ground in flat back steel. The key to the Northfield was the infeed and outfeed tables slid in and out for his knife clearance along with the standard up and down for depth of cut. A top-mounted power feed pushed the material. Sound kind of familiar?
You mentioned that all the old moulders were restoration projects. To an extent, that is true, but if you are going to invest in a moulder head, moulder tooling, and moulder setup, why not put your efforts into a moulder? There are more and more XL's, Poulsens, and even Mattisons popping up at very reasonable prices and they are very rebuildable, and can make you money.
But if the challenge of this project or whatever is driving you, I will offer some advice so you will have an idea of what to expect.
Be prepared for failure! Even the best designer-inventors failed miserably in their first attempts. Usually by the second or third prototype you will have learned enough to make a machine that will function in a crude sort of way. You should be prepared for the cost of this, plus you will be losing $1000 per week.
Be persistent! Don't let your early failures discourage you. By now you will have so much time and money invested that you will have to make this new machine and sell it to recoup your investment. Most successful designers are obsessed with their ideas and will continue regardless of the costs.
Keep your sense of humor! Others will laugh at your early attempts and someday you will laugh too, but maybe not until some time has passed. Don't let it get you down.
Some design pointers:
1. They measure the thickness of the steel in a tank in inches, not eights.
2. The thickness tolerance of the steel in structural tubing can vary by 20-30 thousands, the straightness by more than that. Plus, welding structural tubing is guaranteed to warp it even when you can balance the weld stresses with proper design. The only way to avoid it is with massive fixtures and they can only lessen the effect, not prevent it.
3. You can't afford fixtures until your design is finalized, so be prepared for some expensive machining, such as line boring after assembly.
4. Watch out for the harmonic vibration potential at moulder head speeds. Sometimes the vibrations can only be dampened by castings or true tank type designs, i.e. very thick steel plates.
There was a very good article in one of the machine design magazines a long time ago about the young engineer that calculated all the loads and stresses for a new machine and came up with an appropriate design. His supervisor just glanced at it and said "it doesn't look strong enough, beef it up a little." Even though that seems arbitrary, there is no way you can anticipate all the loads that will be placed on your new machine. Just imagine what would happen if you got a board stuck so tight that the adjustments would not open. Then imagine hooking a come-along to the board and when that fails, hooking the forklift to it. If that sounds extreme, try a pipe wrench on the adjustment screws and then an extension on the pipe wrench.
If you decide to continue with your new moulder, I hope you can make it work and more importantly, make some money.
Comment from contributor A:
First of all, Mr. Biesmeyer is a retired engineer.
My company has its own machine shop and engineer. We have made many saws, conveyors, etc., but our molders are Weinig.
The flange bearings will probably fail under the dynamic loads and speeds you are considering. Check their ratings and find a way to calculate the loads from the cuts you intend to make. Then add a safety factor. We use 5 times as a safety factor and that is probably pushing it.
Look into higher grade bearings and make the housings big and heavy.
Weinig made a welded machine several years ago and abandoned it quickly. If you are going to fabricate a machine, think heavy, like 1" cold rolled. We have one saw we made and it is constucted with 6" sq tube 1/2" wall. It only pulls an 8" saw blade with 5 hp. The loads of a small saw blade are nothing compared to what you are talking about. I still think your project has merits. Think better, faster, stronger, safer.
