Rounding Over Corners on Blocks (Mass Production)

Woodworkers brainstorm in search of a high-volume, high-accuracy production method for a repetitive task of rounding over corners on small hardwood blocks. September 15, 2011

Question
For reasons that are too complicated to explain, we'd like to grind a radius on the edges of crosscut ends with a grinding wheel. Anybody had experience minimizing burning? Grit size? Wheel speed? Cooling?

Forum Responses
(Solid Wood Machining Forum)
From contributor R:
Due to the lack of info, it's hard to give much of an answer, but a grindstone for wood is the wrong tool. There are carving wheels - abrasive wheels for angle and die grinders - that will work well and not burn.


From the original questioner:
Well, okay - abrasive wheels then. This doesn't work well on a router because of chip out. Might work if we could climb cut, but there's no easy way to do this. We have to soften many thousands of short edges (to about 3/32 radius) and presently do this on a horizontal belt sander. But this has a rather vague result and is exceedingly time consuming.

From contributor D:
So why not climb cut then? It's a small cut, so not too dangerous as far as the hand router trying to get away from you. Better yet, set up a sliding jig on a router table, like a coping sled. Abrasive wheels will clog even faster than the belt you're using now.

From the original questioner:
Well... let's put it this way. We are rounding the 8 end edges of about 500,000 pieces of wood of varying lengths from 1.5" to about 12" (per year). That's 4,000,000 edges. 40,000,000 in the last ten years. We do this using workers positioned at a stationary belt sander, and not as well as I would like. Takes a little less than a second to do each edge.

It's possible they could control a router run in reverse, but I have visions of chunks of wood hurtling across the shop floor and braining the gal at the next work station. The alternate vision is of a wheel with an indent radiused into it and a tray to position and feed the piece into the groove - sort of like the meat slicer at a delicatessen. "Grinding wheel" is a misnomer - any sort of abrasive wheel would be fine. But the operative questions are: material (AlOx?), grit, speed of the wheel, speed of the presentation.


From contributor H:
What are you making? What kind of wood? It sounds like a busy, productive place.

From contributor D:
Less than a second is pretty good. Much quicker than clamping into a coping sled, even one with a pneumatic clamp. A belt sander could be custom made to hit two edges at a time. Our glass department here has a dual belt machine with the belts horizontally opposed in an X with silicon carbide belts to soften sharp glass edges. Safety is even more of a concern, I'd think, with a belt sander though. Gripping a piece the wrong way could allow it to whip out of your hands pretty easily and possibly hit someone. I imagine you've seen this by now. A custom router bit could be made to hit both sides as well if your parts have consistent thickness.

My bet is, you could call every custom tooling manufacturer out there and no one will advise using a grinding or sanding wheel, not for that kind of volume anyway. The problem is the number of grits hitting your part per second in a belt versus a wheel. Unless it is a huge wheel, there's no comparison. Lots of things like this were tried a few years ago for sanding raised panel hips with custom made abrasive wheels run by CNC machines. We looked into it and saw no one out there doing it with any success. The sanding inserts clogged too fast and were a pain to change and align properly. The only things that seemed to work were some flutter wheels of very fine grit used for polishing and denibbing.


From contributor K:
What about sandblasting?

From the original questioner:
We've thought of the flutter wheel idea, but it didn't work well on hard maple and is down in the store room. We've tried tumbling, but this isn't easy to control and makes little scratches on the rest of the material. We've thought about the X-sander idea, but not tried to implement it. And indeed - sanding on a belt sander does send a block flying from time to time. We've also tried a high pressure steel die to squish it (wet and dry) and it worked a little bit, but not well enough.

In olden days, some of these blocks were made on small rotary shapers made by Onsrud - but this calls for an entirely revised manufacturing process.

We've thought about using something like an edge bander - the kind that trims the end edges on thick banding - but we just have a lot of small pieces and can't figure out a feed mechanism. And we've pondered the CNC route quite a bit. We've even asked the same question here about every 18 months, without much success.

The best success is with a router, and the best mental success is some sort of device to control the speed so we can climb cut. But I spent some time grinding a round edge on a grinder last week and it worked, though it burned pretty badly. Darned thing is - we have a competitor who can do this.


From contributor K:
Perhaps high-speed rotary methods are the wrong way. In the printing business we used a corner-rounding device. Like a guillotine paper cutter, only with a radius cutter instead of straight. Remember the old time miter trimmer? A very sharp blade was moved through the wood with a lever. A radius cutter on the inside of a 90 degree V block driven by an air cylinder would index and cut in one motion. Drive the entire V block up and down within some guide ways and in 4 flips of the work piece, you're done. Very little dust and almost no exposed sharp edges. Plus you're getting a planed surface, not a sanded one. A wooden model shouldn’t be too hard to build to test the idea.

From the original questioner:
I like this guillotine idea. I used to have one of those 45 degree guillotines for mitering frames, and it was sweet.

But it seems likely that if I can use a stationary belt sander without burning the wood, I can also use a grinding wheel run at a speed mimicking the speed of the belt and having the same grit (about 80 AlOx). I don't see the physical difference, where the rubber meets the road. From the perspective of the piece of wood, it just looks like a rocky area.


From contributor D:
A long belt has time to cool and each little grain, being worked less than on a small wheel, wears longer. Even with CNC machines, we still bandsaw and edge sand some custom casing because it's quicker. The bigger edge sanders (8' long versus 4' long) remove stock quicker. More fresh grit hitting the work piece. Same rpm motors and same grit. Our larger wide belt sander, with 103" belts, can run longer and cut cleaner than our old one with 60" belts. Abrasives, unlike cutters, are ablative and blunt quickly. The exception are silicon carbide (black) belts, where the grains break off in shards and remain sharp until they wear all the way off. Trouble is they often cause fish-eye when finishing wood, which may or may not be a problem for you.

From the original questioner:
No finishing is required. We could certainly cool the wheel with nitrogen or air. But I'm guessing this thread is played out - nobody knows much about grinding wood with grinding wheels. Still waiting for Godot. Here's a picture of what our competitor can do.



From contributor M:
There are firm sanding (Bardo) wheels that can be shaped to whatever profile you need. Grinding wheels don't work because they load up, that's why you can't grind aluminum on a bench grinder.

Looking at the picture, your competitor is machine cutting those edges somehow - they are very clean and precise. A router/routers in some form or fashion is the ticket and the risk of flying parts is way less than sanding. There use to be top and bottom router bits available, or you could have one made.


From the original questioner:
Yes. We've thought about that. The way the old rotary shapers work is that a blank was mounted on top of a template, held down on a rotating table, and a shaper arm came in from the side and made... let's say a canister top as the table rotated. A bearing rode on the template and the shaper head trimmed the blank. (We still see some of the W-28s for sale on the Machinery Exchange).

Trouble is that this is getting into more engineering than we can manage - but the same idea with a router might potentially work. It'd be a 30K experiment, however, and we're not quite ready for that.


From contributor B:
There are custom machine makers that can make a special machine to do this process. I'd start by talking to them.

My first calls would be to:
US Concepts
Unique Machine

There are many other companies out there that could help you.


From the original questioner:
Thanks. We've tried that as well without much success, but it's probably the right answer.

From contributor T:
Why not a small router with a bit and bearing mounted upside down in a table? We have done routing like this before. A sharp router bit on that small of a radius shouldn't have any tear out.

From the original questioner:
We've actually used a pin router to do this with some success. The biggest problem is that it's slow - but it certainly has its uses for odd shapes. Over the years, we keep returning to the router run in climb-cut mode idea, but the grinding wheel needs to be explored further I think. Remember that material, speed and grit is where we started this discussion and we are not convinced that this is impossible. Something similar to a shaper head could work.

One key here is that the solution has to be sleepy proof. This is an incredibly boring job and has to be set up in a way that is as foolproof as the belt sander. Otherwise someone nicks a finger (at best). Love my Sawstop.

The custom machinery idea is probably the way to go - but this also has pitfalls. It's a great way to flush 20K down the drain.


From contributor S:
Stop thinking of a hand type operation to do these cuts. Get away from traditional one man shop tools and realize you are a producer of millions of units. Use of your hand labor should be shifting to load/unload a conveyor that will feed these parts past the cutter(s). This eliminates the sleepy problem, keeps hands out of harm's way, automates the feed speed for optimal cut and production without tearout or burning. To have individuals handling each of these parts to make cuts is expensive, risky, unpredictable, and totally out of date.

Small parts edging/handling is a very old problem and has been solved many times before you - as your competition knows. Get more aggressive about the subject and talk to machine dealers that are big and old, and find their old guy and talk to him about companies that have the same needs and how they do it. The Northeast has a history of small parts production - turnings, toothpicks, treen, etc.

And get away from router bits. Insert/shear tooling on a real shaper(s) or tenoner will give the best quality of cut, be easiest to change, and be safest - with a proper part handing process in place.

Watch "How It Is Made" on cable TV - it will change your mind as to part handling when you see 2,000 light bulbs made per hour.


From the original questioner:
Good idea. But after a few years of talking to machinery engineers, I realize this is far from a solution - at least one within the realm of 30K machines. (The idea of crushing the corners in a press was the latest idea from an engineer - but it didn't work. Works for basswood, but doesn't work for hard maple). A purpose built solution often involves a good deal of experimentation, which is very expensive. It's a trial and error proposition with an uncertain cost and an uncertain outcome - and I can assure you that this problem has a number of complexities that make it quite hard. Engineers aren't magicians - and they have to get paid. If we found the old guy we would be a helluva lot closer, but apparently he died or doesn't lurk on this web site.

Moreover, the fully engineered solution is likely to bear a resemblance to the router solution, though with conveyors, lasers, and a big red button (push). The trick here is to find a way station - better than what we've got, far from perfect.


From contributor D:
I was just responding to the grinding wheel topic.

If it were me, I'd nest as many of those parts that could fit on a 4' x 20' sheet of maple. Nest them using Alphacam and run it on our CNC. Stock slightly over thickness, plunge to proper depth and roundover (or do both in one operation with a custom bit), then unload those sheets onto a cart and run them through the wide belt with a cart to catch all the pieces as they fall out on the outfeed. I'd still hand rout the bottom side as contributor T said, but it's only one face and not even climb cut. Just hit crossgrain side first and go around. While the CNC is running, one person could get a lot done - you won't need to stare at it. I have no doubt this will be faster and more accurate than hand sanding with a belt, grinder, or whatever widget.


From contributor S:
I do understand your frustrations, and my old guy was a hopeful direction at best. Do not talk to engineers - talk to people that sell industrial equipment. They have a lot of time on their hands nowadays, and pretty much have given up hope of selling new equipment.

The fact remains that this problem is not unique to you, and has been solved many times before. You don't need to engineer a new solution, just find an existing one that can be adapted. Do not think of breaking new ground - way too expensive and iffy. If I need to cut a board, I do not start with tooling geometry and experimenting with different rim speeds and methods of holding the work - all I do is think first if I'm ripping or crosscutting, then go to the appropriate saw.

There is almost no precedent for a grindstone in this application, so I would encourage you to drop that since it demands you experiment and engineer. It is a sign of desperation, not solution.

It will also be helpful if you can implement in small steps. One conveyor system feeding past a shaper for primary operations, then later a secondary can be set up for other operations. Again, this is not engineering, it is process.


From the original questioner:
The CNC might work if we could find a maple tree 4' thick - otherwise there would be a lot of trouble getting that 4' by 20' piece (These are solid wood - 1-3/8 thick). But actually, this solution has some potential, though it leads up many blind alleys.

The uniform size problem also has a lot of ifs. Periodically we beat the stuffing out of the guy who runs the Weinig, but even so it's tough to stay within 1/100th. Then, when you get a couple of thousand feet of something that's off by 2/100ths, you kind of have to use it.

The engineering solution is probably the most promising for ultimate success - but it's impractical. Unfortunately, this is a very competitive product, and made more so by imports using cheaper woods (rubberwood). That means there's not much engineering money, and engineers are slow to respond to queries when dealing with a tiny company with an odd product. In addition, there's a lack of engineers - starving or not. So you end up writing fruitlessly to XYZ engineering and they quickly get tired of the whole thing - just not worth their time when they could be figuring out how to repair the carbon fiber wings on a Dreamliner.

We actually spent quite a bit of time exploring patent applications and while the answer is probably in there somewhere - we haven't found it yet. (The edge crushing idea came from there - but it didn't work).

In the short run, we're going to solve this with a home built solution or not solve it at all. Or find the old guy.


From contributor I:
This process could easily be done on a shape and sand machine with 2 shapers and 2 sanders. The shapers would have counter rotating cutters with jump cope to eliminate the tear out. Then you could sand with 1 or 2 sanding heads (depending on the final grit you need). This is easily done on a standard machine.

From contributor D:
We also have an RF press that can edge glue a 4' x 20' sheet of maple boards in 5 minutes. The CNC will be cutting so fast it will make your head spin. Really there is nothing unique or special required. CNC router, wide belt sander, an RF press - all this stuff is for sale today at good prices all over the country. Think too - not only is a CNC good for this, but a multitude of other tasks. Half a million parts I am sure would not take a year. No way. These are big purchases, but nothing weird or unusable for other tasks. They are basic machines used in many manufacturing processes. If your competition has these tools, you are at a disadvantage.

From contributor B:
You could also buy a used large fast edge bander and just use the roundover heads.

From the original questioner:
I suppose it would be just as easy to CNC a piece 6" wide, so that could work. It also allows making more complicated pieces - which would be a good thing. But the idea of doing one side with the CNC, sanding it open, then doing the other side by hand wouldn't work - conceivably there's a solution to this, though it doesn't spring to mind.

The notion of a skip cope, though, sounds much more plausible and I hadn't thought of this - I'm not even absolutely sure I understand - though I think I do. The difficulty I see there is a suitable feed mechanism, since these rectangles are many different lengths, but we're waiting to hear more about this. I like it.


From contributor D:
People do flip sheets and run the mirror image. I don't because our CNC machines are not flat table - they are pod and rail setups. Flat tables have more holding power on sheets and therefore less chance of a part shifting. Sheets are more efficient for large numbers of small parts because you can nest lots of them at a time - less material handling between cutting cycles. But with such a small cut to make, I might try it anyway with a convertible flat table I made. I'd time myself and see which is faster. The accuracy of a CNC is way better, too. Forget hundredths. You'll be mic'ing parts and measuring in thousandths.

From contributor S:
Your Weinig is capable of thousandths also. I ran one for years where the two operators held within .005 every day, on over 50 patterns. If your operator is not capable, then he/she can be trained/supervised or replaced. Or a shop super can sign off on Go - No go sheets with gauges. That should be the least of your problems.

Thinking about your reluctance to fund new machinery, I bet lunch you have already paid for your 30K or more machine, you just don't have it. Your employees sanding/shaping corners by hand have taken this money home in their wages. Nothing wrong with employment, but you are paying for the machine every day you don't have it.

Do a cost/benefit analysis and see where you are. I think you will owe me lunch if you took the bet. Imagine running everything without the Weinig, and how your costs would soar while losing accuracy and predictability.


From contributor J:
I think contributor B has the easiest answer. This shape is routinely machined on 3mm edgebanding. Find an old used edgebander that does corner and end rounding and remove the gluepot and rough trim station. In fact, try to find one really cheap that has a burnt out gluepot.

As far as machine designers/engineers, look to a machine design company that builds automation lines for factories such as auto parts manufacturers. These guys routinely build small and unique machines to do just about anything.


From the original questioner:
Yes, the edgebander idea has always appealed to us because of the end-edge rounding. The problem we have had with considering an old banding machine has to do with the size of the pieces, and the problem of top feed rollers and the like - though it's possible this could be worked through with enough reengineering. Mind you, many of these pieces have a profile of 11/16 by 1-3/8 on the end. Pretty small and only 2-3/4 long. These would tend to disappear in an edgebander. But we have considered this. The problem is the thought of ending up with a surplus 800 lb edge bander (with a bad glue pot) in the storage building - got enough of those tools already.

But I've got to admit this thread has generated a lot of possible advice. At least I know that the solution isn't just sitting there and I'll feel really stupid in about five more years. We've got four or five other designs in mind as well - and they don't work either. But thanks.


From contributor D:
A small part, 11/16 x 1 3/8 x 2 3/4, will be at risk of shifting, I admit. Building skill with a CNC is no different than, say, hand chiseling. Trial and error led me to leaving tabs, much like model airplane kits have that we all probably got as kids, for tiny parts. Vacuum hold-down depends on surface area, so linking small stuff to the sheet is the way to go. It requires some trial and error, but in fact parts can be snapped off by hand with just the right tab.

A certain large architectural millwork company went out of business a couple years ago after getting their ass sued off from copying a patented process for producing custom grills for windows. Their process wasn't really all that innovative and we found a way to make these parts using our CNC, albeit somewhat modified.

We save a lot of money and time not outsourcing this. Lead times go literally from weeks to minutes. Charging more for rush orders doesn't affect us out in the shop - the machines are doing the work; all I do is change whose stuff is getting cut first.

I just can't imagine your competitor is not using CNC technology. It's just a jig. Using numbered dimensions instead of hard patterns, only moving exactly where, how fast, spinning how fast, and with what tool you specify. It's a robot basically. Robots can move fast and not get tired - their operators are thinking more about keeping them fed with stock and removing it quickly than actually shaping it.

I think the bottom line is, you either embrace change or hold onto the past. I have a guy here that can often glance at dozens of shapes on a screen and rearrange them, getting more parts per sheet than a complex algorithm developed by Alphacam, a program used to make parts for the space shuttle. He can't freehand a damn thing on a bandsaw or hand chisel anything, but he's very meticulous and he's always got a job here. It's a new era. I have evolved in this woodworking industry and can no longer take pride in hand shaping anything, other than a boat.

I don't doubt a super-crafty engineer (old dude) could design a nice little station that magically produced your parts at a rapid rate. Us mere mortals, though, are stuck with using what's already out there.


From the original questioner:
We've thought about CNC, and not just for this, as we make a number of shapes other than rectangles that would ideally be cut with a CNC. However, the tech shift is more formidable. As matters stand, we run 10-15,000 feet of profile molding on a molding machine, which rounds the corners in the long dimension, and then we chop these pieces to the varying lengths as we go along, defecting as we go. As a practical matter, we've long pondered the use of upcut saws and defecting feeds from OMGA and others, though these turn out to be a good bit slower than what we are already doing.

These molded lengths are pretty straight, but not sufficiently straight to lay down on a CNC to cut the lengths. Using a CNC would probably tend toward stopping at the ripping stage and letting the CNC do both length and width. And this is feasible, but only if we could do both the top round and the bottom round at the same time. I can see this too as a possibility, but I'm dubious about flipping the length over and doing the back side as a second go.

Actually, the process as I envision it would not use vacuum, but hold-downs spaced at intervals not-the-same as the intervals of the pieces (all pieces are the following lengths: 1-3/8, 2-3/4, 5-1/2, 11, and 22"). The bit could be a custom over and under bit, and I expect we could keep the planed thicknesses pretty tight.

How many people make face frames on their CNC? This is a process closer to what we are doing. But I like this idea. It has potential.


From contributor D:
I might actually have been singing the praises of CNC too much, after better understanding what you do. A router won't keep up with a moulder, so if most of your parts are run lineal 10-15k ft, then a CNC router is not the tool for the job.

Flipping sheets on a CNC is viable for weird stuff, but you have to be careful that your reference edges are exact, and that the sheet is referenced perfectly on the pins after flipping. Usually check yourself with some small scrap before going all out on massive expensive sheets.

We have pod and rail machines which allow machining from the side, and are ideal for solid wood door and window components. Small stuff is tricky though, and often keeps me up nights thinking of new and better ways to machine them.

But unless you really just like new toys or have more variety of shapes, I really can't see a CNC router beating your current method, to be honest.

Since your lineal stock is already rounded over, your blowout risk is greater. Typical rule of thumb for cope and stick machining on a CNC is crossgrain first.

So here's an idea - build a sled, say 8' long. Get someone with a CNC to do this, as it will be quicker. Basically a couple slabs of HDF about 2" thick and 8" wide. Have a series of dadoes machined 11/16" (half your 1 3/8" stock thickness) deep by whatever width your stock is from the moulder. A 3/32" core box bit will be needed to machine the corners. It will look like a ladder. Set it on a table and with a straight edge or fence, place all your length cut parts into the female molds and then the matching top on it to sandwich your parts. It must be a tight fit or this won't work. Then run this sled through a shaper, cutting top and bottom roundovers, using a power feeder. The HDF sandwich acts just like coping backers to prevent blowout. Eventually when the backers get too beat up and aren't snug against your parts, just shave off a little on the table saw until you get a nice crisp edge. HDF should hold up to at least a couple dozen runs before needing a shave.

I can imagine a setup where your workers are clamping parts into these sandwiches to feed shapers, which you probably have, and if not they aren't that expensive (unless you want a Martin). I'd probably just counter bore every foot or so with square drive screws and a clutch set screw gun (to avoid stripping out) for speed. The power feed roller pressure alone may be enough to squeeze the sandwich together as it goes through the shaper. You'll have to experiment.


From contributor Y:
Check out the Accu-Systems HPMT machines. If you are processing your stock with a moulder and applying the rounded edge on long stock, then you could cut to length and place into a machine similar to this to roundover the four edges on the fresh cut.

From the original questioner:
That is pretty slick. And I believe it might do what we want, though it's not clear to me how to feed it. But I don't even want to guess at the price. I talked to a guy at one of the CNC companies the other day and he asked if we were thinking in the 200K range. "No," sez I - "we're not."

From contributor B:
For what you need it would not be that much. As I said, I would approach custom machine manufacturers like Accu-Systems with your problem. I would hope they could build a feeder into it. Before you freak out on the cost, you might want to consider your current annual cost of people sanding the corners off. One machine could do it all every day all day.

If you really embraced the technology I bet you could feed it lineal off the molder and they could build a machine to cut to length and round the corners. If you could cut your people to one or two and produce the same output, would you spend 100K once?


From the original questioner:
Well... got a Ph.D. in statistics in the distant past, so I guess I can figure out how to calculate the savings - but this raises some philosophical questions. Part of the problem is that I can't ask the machine to go up on the roof and mop sealant where the screws popped out, or babysit the dogs when I go on vacation. I know there is no way to win this kind of discussion - but my employees have been with me a long time and my enthusiasm for replacing them with a hunk of iron is limited. Sure it's cheaper in the long run, sure it doesn't whine all the time, sure it doesn't get sick or develop repetitive motion injuries, sure it doesn't require medical insurance or a pension plan or unemployment, sure we can afford it - okay, where was I?

Here's the deal. We already know that we can chop blocks faster on a table saw than we can on a pop-up with a defecting feed system. The question here might be - is there something simple that will work? I am looking hard at these humongous machines and they might work, but in the back of my mind I keep thinking there's a system I can make out there for about 1K that Ruth can use to round the corners more sweetly than with the belt sander.

Probably not - but I'm still wondering. I'm reminded that Mark Twain lost his entire fortune trying to fund the development of an automatic print setting machine. Machines are great. But there's also overkill, and something about this computer controlled mechanization is irksome. I saw a robot the other day that will tie shoes - I just didn't know this was a crying need.


From contributor S:
Going back to your earlier info, you said you do 4,000,000 corners a year, at about a second each. That is only 1,100 hours a year, or about 21 hours a week. Your other posts say there were several people doing this operation. I think you are at probably about 3 seconds per edge, if not more. 4 seconds x 4m = 4,400hrs/yr - about two full time employees. If they cost you $15.00 per hr, then you are now spending $66,000.00 per year for this work.

This is what I mean by saying you are already "buying" the machine in COGS, but you do not have the asset in your possession, and you are not benefiting from the expenditure.

I think you should do a cost analysis of the whole operation and see what the current work really costs, then you will know what you can budget to spend on a machine in a typical 5-year payback cycle. If you can semi-automate and go from 66k labor to 20k labor, that allows you 46k a year x 5 for the machinery, roughly. Once you own it, your costs will drop dramatically.

If you can produce a better product for the marketplace, then you can sell more, or raise prices, or both. Either will pay the machinery off sooner.


From contributor K:
The Cyklos Corner Rounder CCR 40 fitted with a custom die and air cylinder should work. I think a stack of paper 1.5" (40mm) would be harder to trim than a piece of maple.

From contributor B:
I am not suggesting the goal is to eliminate employees. I have a lot of great loyal employees. We (the employees and I) laugh all the time at some of our equipment purchases. A simple example would be a wide belt sander. We have a segmented platen veneer sander. We sand all the plywood that goes into production with it. It used to be sanded by hand. If I tried to take that machine out of the shop, there would be a mutiny.

If you had a machine that could take your current hand process and make it easier and faster, reduce your lead time and cost, might you take business from your competitor or open doors into new markets? Then you would need those employees to package or do something else.

I have done every job in the shop and if it is dangerous, uncomfortable, or will put you to sleep, we look for a better, faster, easier way. We have added different pieces of CNC equipment to do different things over the years. It is usually a leap forward in productivity, quality and profit.

I'll bet your cycle time is longer than you think. The cycle time is how many pieces a person can make in a day, divided by the hours. All the handling before and after counts also (people or machines, it must be counted in the calculation).


From contributor S:
Your employees are valuable, and that is good. At the risk of sounding like one of those plaid jacketed machine salesmen, I'd agree they are too valuable to have repetitive motion problems, or other compromising work related injuries or risks. With the arrival of new equipment, there will be room for advancement for some, and a variety of work for others.

Your business will change, and I sense that is the real hurdle in this conversation. I (and others here on the forum) make the assumption you want to cut costs while solving a production problem, and you have gotten some world class advice.

It is your business, and you can (and should) run it any way you want, but you still have to fit within the constraints of real world business. You apparently have some worthy competition, and I'll bet lunch they are not placing dog-sitting ahead of cost cutting operational equipment.

A 1k solution is not available to you. However, by looking at your costs, you can determine what you can afford to shop with, and search for solutions that are truly successful. When you reduce per unit cost, you make more money for things well beyond mopping tar. But only if you really want to.


From contributor U:
With an item that size, a Porter Cable trim router with a good roundover bit would be the way to go in my book. A lot of the new router bits are designed in such a way that you can climb cut without a problem. The Porter Cable trim router is about the best and easiest to use.

From contributor B:
A hand router on 4 million of them?

From contributor Q:
Some of the answers here seem new to you, and yet obvious things to try. How good are your machinery dealers and manufacturers if they haven't either suggested these things or told you why they won't work? Could you be asking better people?

I'm also surprised the machinery people have not done the math for you to show you how you can afford to invest. A steady market for a half million parts is a great asset, even if they are low cost parts. The joy of talking to a truly good salesman is that they will do a lot of the analysis you need to make a good decision. With your background in math and analysis, you can surely see through any false assumptions and bad calculations you may get.

Last, but most important - from some of your responses, it sounds like your first step might be taking a close look at your attitudes. What are you afraid of losing by committing to changing this situation? You don't seem quite sold on the idea of fixing this. That's not a bad thing, you just need to move from there and explore your reasons for holding on. As you look closely and challenge your assumptions, you may find that life continues with the same joy and a little more change to jingle in your pockets. Automation need not be faceless corporate jail time; it can be liberating if you make it so. Imagine, would it help your situation if you could produce arched or curved blocks, or other specials that start with your current product and lift it into a higher priced niche?

The world is a lot bigger these days. It's not just the guy around the corner with a table saw in his garage, it's the fellow in China with lower wages and government support and an internet connection. It's a lot harder to isolate yourself than ever, and there are more ways to adapt than before too. Change is a part of our lives now, and if you don't flow with it you will have to buck it.


From the original questioner:
We'd like to fix this, by all means. But the solution here is tougher than you surmise. First, we do not expect to increase the volume of business much even if we were able to lower the price by automating the operation. This is a niche product and not likely to expand a great deal. This means that the credit calculation is a problem (though our credit is well-neigh perfect). We have to be able to afford to do this with current cash flow.

Second, there is no easy automated solution. If you read these threads, you will see for yourself that these are mostly dead ends. The one that we've looked at the hardest is using an old edgebander, but this is stymied by figuring out how to feed it. The little tenoning machine solution (above) also looks to be a real possibility, but no clear cut way to feed it, either. We've talked to quite a few machinery salesmen over the years and they do not have a clear solution to offer. In many cases, we have discussed potential solutions directly with the persons responding to this thread and they have all agreed that what they thought would work - will not. And we have talked privately to all or most of the specialty machine manufacturers - ditto. Finally, we have discussed this with custom machinery engineers (well, okay - one engineer) and he couldn't think of anything that worked after two months of experimenting.

As to the matter of willingness - let me say this: we are willing to look at a solution in the less than 30K range, if we think it works and is demonstrably faster. At the same time, I should also tell you that my mother-in-law made a couple of million buying and selling quilts from Amish lady-friends (we are Mennonites) made by hand. These were made by a bunch of women sitting in a circle in the 1970s and 80s. We don't see automation as a panacea. We know where all this secondhand and foreclosed machinery comes from. And we have little enthusiasm for monthly payments that can't be laid-off.

I believe that a CNC machine could be modified to do this, though it is not clear to me that it would be faster. The great advantage is that this machine could be used for other things. I also think that some of the solutions using a trim router could be developed, would be almost as fast as using the belt sander (this takes about 2-4 seconds per edge) and would do a better, more even job. I also think that a custom machine could be developed operating along the lines of the old Onsrud (W-28) autoshapers - though we are reluctant to pay the development costs without more confidence in the end result.

I think that a solution here is likely to be more gradual. First a method that will accomplish this more simply (by hand); then an automated version of the same method that will do it automatically. That said, we're always happy to talk to machinery salesmen and we can finance anything we want (within reason).


From contributor U:
A router table with a roundover bit and a ball bearing might be the simplest way to do this and the cheapest. Get the right bit and you could climb cut it.

From the original questioner:
Some version of the roundover bit is a good potential answer. The issue here is how to work out a feed system that allows climb cutting. We've tried roundover bits many times, of course, but the chip out is a problem and the climb cutting has a tendency to get out of control. But as I said first off, we think that a feed system can be made that will potentially solve this problem and we can imagine a jig that will allow for rapidly flipping the block over and doing all four edges. This is probably the route we will take as we begin to experiment in the spring.

A few years ago we bought a container of blocks from Bulgaria, and these had been rounded with a router. It doesn't work for the smallest sizes, but these are a minor problem and can always be done by hand.


From contributor U:
A small router bit, Freud or CMT most likely, you can climb cut safely. The Porter Cable trim router would be best. I have a Bosch and I don't like it. A router table with a high fence you could work holding the piece vertical including the ends. That might be the easiest on the people doing it. From what you said you have help available.

Use a crate of some kind to hold the work for easy access of product. At a place I used to work we had crates for parts and moved them with a small lift cart.


From contributor G:
How about a double end tenoner or end matcher set up with cutters to do the top and bottom radius on both ends at the same time? Crank it in or out to change lengths. Then reset the machine and tooling to do the same standing on edge to radius the 2 edges on both ends at the same time. Could also have sanding wheels hit the radius as it goes by on the feed chain. Moulded stock would have to be within tight tolerance or you get a ridge from the end tooling. Use same templates on grinders to ensure consistent radius when resharpening. If you had two machines set up there would be no changeover. Could get several thousand pieces per hour with two men instead of a couple hundred per hour. Lots of used machines in the market now - maybe you can get a good deal and if your product changes, you can sell the equipment back to the door/flooring guys.

From contributor B:
How about a sled to carry multiples of the blocks through an edgebander? Use vacuum or clamping pressure or both to hold the parts. You could use a vacuum fixture to grab all the blocks and rotate them at once.

From the original questioner:
A couple of these ideas (double end tenoner, end matcher, edgebander) have occurred to us, though the wide range of sizes and numerous small sizes are a problem. I'm not really familiar with end matchers, though I have a rough idea.

Trying to clamp these up in a sandwich/jig is probably impractical due to the sheer numbers and sizes. Mind you we are looking for a solution in the range of 30 seconds per piece to do eight edges and corners with a wide range of sizes.

I'm for trying the Porter Cable idea. I can see how to weld up a router table so it stands at 45 degrees and make a sled based on linear bearings. And I can see how to flip the blocks over in order to do all eight edges quickly. Might work.


From contributor S:
I hope this thread is preserved in the Knowledge Base as an excellent dissection of one shop's consideration of production technology. Beyond the crisp analysis of business costs and drive to succeed lies the personal preferences and desire for stability.
World class advice from a wide range of experience describes everything from customized numerical controlled equipment and sensors to P-C trim routers. Original low budget gets increased, but is not held in context of cost-benefit analysis. Employees vs machines. Competition. Low tech favored over unknown tech.

From contributor U:
If you plan to use a router setup, be best to buy a router table top for the top. The fence should be 90 degrees. You can run them flat and turn them up to do the corners or run them vertically. With all that and the amount you want to do a heavier router with a 1/2 shank? Sometimes simpler can be best. You can use a flap sander to sand the edges if needed. Get a routine started and you should be able to crank them out.

From contributor O:
I worked with robots in college. There are a lot of out of work robotic people in the Michigan Detroit area... Due to cutbacks in the auto industry there are many surplus robots waiting for new owners. This is a Domino imprinting/boxing line you could use for inspiration.

You could use a robot to pick and machine the blocks within a set of custom jaws. Could probably use a laminate trimmer and small sander on such small parts.

Our robotic class had industrial sponsors pay for the equipment and let the class loose on projects like this. You could sponsor a college robotics class to do similar projects.


From contributor P:
I will go out on a limb and guess that you are making children's blocks, or something like them (moulder run of eased-edge strips, lengths in multiples of 2X, eased ends, hardwood). One way to use a CNC would be to stack the boards on a fixture (you could even clamp instead of vacuum), so that you have a long width of blocks with their 1-3/8" faces adjacent to one another and aligned on one end. (Kind of like a four foot wide butcher block without glue). With the ends just 1/4" over the edge of a raised bed, put a 3/32" radius pointed roundover bit into the changer and set the tooling axis so it is horizontal. Have the machine make vertical cuts in 11/16" increments down the four foot length of the ends. This will cut the long edges of the ends. Then make a horizontal cut along the four foot wide top and bottom. This will cut the short edges of the ends. If you could gang pieces of the same length, you could use this procedure to cut both ends in one clamping iteration.

I don't own nor have I ever operated a CNC, but it seems to me that this should work. Perhaps experienced CNC operators and programmers will find the flaw in this.

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