Dowel, screw, staple, confirmat construction
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Efficiency and assembly with different fastening methods. March 5, 2003
Question
Our firm is considering gearing up to produce Euro P-lam cabinetry using dowel construction. We are currently set up to produce Euro P-lam cabinets using confirmat fasteners. We have a CNC Beam Saw, Edgebander, and a Point to Point drill. We visited the Anaheim show last year and gained interest in dowel construction. My questions are:
1) Is dowel construction more productive than confirmats?
2) Which pieces of machinery would you recommend for dowel construction: CNC point to point with router abilities, case clamp, horizontal drill, dowel insertion machine?
Forum Responses
(From WOODWEB's CNC Forum)
I can't comment on confirmat fasteners because I've never used them, but I have used dowel construction for some time. You already have the major pieces of equipment - CNC beam saw and point to point. You could do horizontal operations on the point to point, but that is a rather slow operation for the machine. You will want to look into buying a dowel insertion machine to handle the horizontal operations between the p2p and the case clamps.
From contributor G:
I'm curious as to why you are looking at getting away from confirmat fasteners. We are actually pursuing the other route and looking at switching from dowel to confirmats. Right now it doesn't look like we will change, but that's mainly because we don't know enough about confirmats. One reason we were thinking of changing is we hoped we could increase our assembly time with mechanical fasteners. With dowels, you're only as fast as you can process boxes through the case clamp. We like ours to sit in the clamp for about 5-7 minutes to make sure the glue is set up good. So without adding another clamp, we are limited in the number of boxes that can be processed. Like I said, though, we probably won't switch because the dowel system is working out well. But we are always looking for that one better way.
From contributor P:
I agree with the above. Dowels are very time consuming, but I can not switch because I have so many finish ends and laminating after assembly is even slower than doweling. Any ideas?
I use Confirmats and switched from dowels. Quite simply, they are faster, or at least they are for me.
The finished ends... I use a field-applied 3/4" panel for a finished end. It sure makes things easier when there's a dinged or chipped end as well.
Brian Personett, forum technical advisor
From contributor G:
We haven't looked into that one tremendously, besides thinking about using finished end panels and applying them on-site. We could make these, height of the cabinet minus toe kick height. This would leave us with an inset that the vinyl base could wrap around into. We would double our white melamine cost, but would this be offset in other areas? We don't know.
From contributor P:
Brian, if you were to nest, what kind of fastener would you use, considering finish end requirement and if you had no end boring capabilities on your router?
If I were to nest, I would probably go the staple and screw route. To me, staple and screw really lends itself to NBM.
For what it's worth, I know there are faster ways to Hbore, but what can I say, I'm lazy - I can throw a piece on one machine and when it comes off it's done.
Brian Personett, forum technical advisor
From contributor P:I agree that the staple and screw method would be fast and efficient, however I still have my finish end problem. I have thought of the
Hafele line of fasteners, but not sure how respected they would be by my customers and they are visible inside the cabinet and fixtures.
Contributor P, look at the "Mod-eez" connectors for your finished ends. Confirmats are the way to go for non-FEs in anything less than high volume.
From contributor R:
As far as I have been able to make out, there doesn't seem to be a huge difference in output between shops that use confirmat and shops that use dowels. Both methods require high levels of machining accuracy. The investment in equipment is smaller with confirmat. To do dowel construction in any quantity, a drill/inserter is a must. I am exploring confirmat for the many off-line cabinets that we do, where assembly needs to be done away from the case clamp for some reason. I recently upgraded my old 4 clamp case clamp to an electronic beam type (and lifted it off the floor to bench height which we should have done years ago), which greatly speeded up matters. I think the key to putting out boxes is in the labeling, sorting and handling of parts and the systematization of assembly. I recently visited a shop that is smaller than mine, with similar but somewhat less sophisticated machinery and they beat my output by about 20% per man in less space simply by an acute focus on efficient movement of parts and minimum waste of motion.
By the way, there's a thread on another site about whether professional organizations are worthwhile - I saw this shop while on an AWI shop tour and I think I got my dues worth to take home just from that trip. There will be some changes at my place by next month, or if we ever slow down for a minute.
Contributor P, on the finished ends, I send a loose 3/4 panel that is field-applied after the cabinets are installed. Basically set the cabinets and pop a few screws into it from inside the cabinet. On the surface it seems a like a great deal more work. In my experience, it's not that big a deal. I typically cut and band all my FEs with the rest of the parts, then ship them loose. They could easily be done off-line as well. Sometimes I order doors and FEs from an outside vendor, so they're completely off-line. No problem.
Another note - we manufacture only, no installation. I've had nothing but positive feedback since going this route. Many times, cabinets are installed, and they don't install the FEs and toe until after other trades are gone, greatly decreasing the chance for scratches, dings, and chips.
If I had to laminate the ends after assembling, I'm with you… that's not an option.
Brian Personett, forum technical advisor
From contributor P:
Brian, I agree with everything you said, however getting back to the question of mechanical fasteners (one example being confirmats) vs doweling (we both agree that confirmats or mechanical fasteners are faster), if we were to machine all parts on a nested base machine with the idea that a CNC router cannot horizontal bore very efficiently or effectively, what kind of assembly system would you recommend with products that are stand-alone fixtures where you can not hide your screw heads by sending a finish end? My only thought was the
Hafele system of fasteners, because they eliminate any end boring altogether, however they are visible inside cabinets and fixtures.
Why is seeing a finished screw head used to attach the applied end from the inside any more objectionable than seeing two great big hinge plates and a couple of connecting bolts?
"Inside" is the operative word. We use the
Hafele minifix on the few Euro jobs we do, since they don't require horizontal boring. If we put them inside the cabinet for the bottom they won't support much weight and we'll have customers suing us for a new set of china, so we're stuck having them on the outside and applying the hokey caps.
Dowel construction, for the most part, is going to give you a better through put than a mechanical fastener. As mentioned, the case clamp dwell time is a limiting factor. I have seen a captive back with a bead of hot melt (applied on the outside, unseen back of the box) holding it while the PVA glue dries.
I have also seen multiple case clamps, or feed-through case clamps - both will increase production.
The best suggestion was increase the flow by moving parts around less. Any steps you take to increase efficiency will pay off, no matter what method you use... What is the most common size batch you run? Does your product lend itself to parts stacking in your panel saw or are you mostly cutting one-sheet patterns?
You have to give a bit more information to have a real discussion of what would be best for you. For instance: A multiple head drill and insertion machine makes short work of a stack of parts, but a dedicated CNC dowel drill and insertion machine is not a bad idea if you want flexible production.
To the original questioner: The one thing I can add is I use dowels in case clamp and for about two years we used wood dowels and put Roo glue in hole and manually taped in the dowel. Then put a bead of glue on the edge of part. Then put cabinet in clamp. But we had problems with sides not staying tight to bottom and tops in the front. Then we used yellow wood glue in the dowel holes, which helped, plus had less clean up. Last year we purchased an Accu Systems hp23 and used pre-glued dowels and their holding power is much greater than the above applications. Also, contributor R could not be more right on movement and sorting of parts prior to building. We have a good system in place now, and though it took awhile to get implemented, it greatly improved efficiency.
