Nested Base Versus Beam Saw and PTP
A closet system fabricator and installer describes his journey through various shop equipment situations. May 26, 2014
I put the items below together for a friend of mine that is in the same business as me. I have been running my own production shop since 2009 when I started with a table saw and a drill press. I have never owned a slider or vertical panel saw; we jumped into a beam saw and line boring machine, then a PTP and now we are nested base. Each time I changed or added equipment, I expanded my product line and improved my existing product. I now offer closet organizers, garage cabinets, murphy wallbeds, home office systems and entertainment centers, as well as occasionally cut parts for other shops.
I share this below for others to see what's involved in each process. I have used my closet system for this time study, although when we were doing home office systems they required even more secondary operations.
Nested Base versus Panel Saw/Secondary Machine
The beam saw is a great machine for cutting up lots of squares and rectangles, especially if they are all the same size. You can load in multiple sheets and it will spit out stacks of 3 parts of the same size very rapidly. The downside is that sometimes you need a lot of parts that arenít the same size and a large number of them need secondary machining for line boring, Rafix fitting, etc. First letís look at material handling and how many times we touch the part in the process. Red text highlights steps that can be done wrong based on operator skill or training.
1. Guy in office creates cut list on excel spreadsheet or from design program.
2. Guy at saw manually enters part sizes into panel saw (this depends on level of saw you have, you may be able to output directly to machine).
3. Load the panel and start the cycle
4. Set aside the rips that come out of the machine
5. Rotate the rips
6. Start the cross cut cycle
7. Unload finished cut parts onto a cart
8. Load remaining rips into the saw
9. Start the next cycle
10. Unload finished rips onto cart
If the above process was for all the same size parts, on most machines you could complete this cycle in approximately 8-10 minutes and assume 3 sheets stacked. In 90% of our work, this was not the case and would involve multiple sizes and could take 12-25 minutes or more to complete a 3 sheet process. Additionally the operator has to be at the saw for this entire time as there are not enough gaps in the process to complete other tasks.
11. Roll carts to edge bander
12. Edge band and run all parts
13. Sort parts at end of bander for secondary machining (parts not always machined)
14. Move cart to secondary machining areas, PTP or Rafix Drilling, hinge boring, pocket screw, etc.
15. For PTP, find part and corresponding barcode and scan to load program. (We were already running a software package that was automatically creating the code. If you donít have that and are writing code at the machine, you find stock parts from your catalog or modify existing for needed parts.)
16. Move pods on machine to make sure they are clear of machining ($100 pods are never hit by tooling, causing damage)
17. Place part on proper side of machine
18. Step on pedal
19. Push green button
20. If part has second side, flip and place part on other side of machine
21. Step on pedal
22. Push green button
23. Remove part from machine
24. Affix rail bracket (no pre-drill, horizontal drill on PTP)
25. Drill fixed shelves on Rafix machine (make sure proper edge is to the stop)
26. Rotate part
27. Drill other side of fixed shelf (make sure proper edge is to the stop)
28. Insert Rafix fitting
29. Sort onto final cart for loading
In our old system we used Grass Zargen Metal sided drawers and the backs and bottoms were cut from ĺĒ white melamine
30. Cut drawer parts to size from full size panels or scrap (see above for loading into saw and material handling, about 6 steps).
31. Edge band backs
32. Drill backs on machine
33. Dado drawer bottom on table saw
34. Load finished drawer parts into 1 of 3 storage cabinets in drawer station area
35. Pull parts from cabinet to assemble drawer
Nested Base Machining
You have to look at this differently. You arenít buying this to replace a line boring machine, you're buying this to change and improve the way that you run your manufacturing facility and offer more options to the customer at a better value. This is not just a CNC router but a complete package that includes software that will not only generate all design drawing but transfer that to code to run all the operations needed automatically. Unlike above process that is trying to reduce secondary machining by eliminating processes, in nested base we look to add any and all processes needed into 1 process. We want no secondary machining. Things that we include in the nesting process: Hinge boring and handles for hardware on slab doors, baseboard and ľ round notches for cabinet that will go over baseboard, cable access hole in cabinets, pre drill the top stretchers with mounting holes for laminate tops and anything else that we might do on a regular basis is written in to the program.
1. Production manager reviews job from designer and makes sure everything is correct on the job.
2. Outputs job to the CNC
3. Operator opens the file for the corresponding job and loads to the work list and verifies that the sheet on the screen matches the printed paper in his hand.
4. CNC operator loads sheet onto CNC
5. Steps on the pedal
6. Pushes the green button
7. 4-6 minutes later, unload machine (1-3 minutes) and places parts onto cart for edgbanding. At this time all machining for ĺĒ melamine parts has been completed including Rafix hole, line boring, hinge boring and handle holes on slab door and drawer fronts, drawer box sub fronts drilled for hardware and screw, we even pre drill the tops on our home office cabinets so we can screw our tops on from underneath, rail bracket route, baseboard notch, grommet holes, cabinet assembly dados and fittings. The only process that we canít do on the CNC is horizontal drilling, which we avoid at all costs. We have 2 operations that we need this and have dedicated jigs for when we need it.
8. Loads next sheet onto CNC, steps on Pedal and pushes green button.
9. While Second sheet is running on CNC, Edge bands parts from first sheet
10. While parts still on cart at end of edge bander, inserts Rafix fittings
11. Pre-drill holes for rail brackets (no horizontal drilling available on nested machine)
12. Install rail brackets
13. Sort and load parts onto final cart for delivery
We have now eliminated the Grass Zargen Drawer system and have nested all of the drawer parts in with the rest of the job. All drawer parts are ĺĒ thick and color matched to the job. The exact number of parts are made for each job and we have no stock parts. We can now easily make drawers in any size that we want. We stock a single type of slide in 5 depths that can be used on all drawers and they are $2-4 per pair vs. the $15-20 per pair of the Grass. Drawer parts use a blind dado/mortise and tenon type construction. All machining was accomplished in the CNC process including pre-drilling holes for assembly screws and guides.
14. Drawer parts are sorted at end of edge bander and laid out for assembly
15. The 5 pieces are assembled and screwed together with the guide in place
My epiphany on this came one day when we had some turnover in the shop. Within one week I fired 2 guys and had a third quit. On Monday morning it was me and a high school intern. The beam saw was too complicated for him to run, you had to keep track of rips, do math in your head, etc. to get things cut in a timely fashion and with good yield. Iím pulling my hair out on the saw and I look over and I have a high schooler with next to no experience loading parts onto my PTP machine. Ding! The light bulb went on - letís eliminate the saw and just go to nested base. Previous to nested base we were doing about the same volume and we needed 2 full time guys in the shop and sometimes a third helper to get things done. When you had a big job a guy could spend 4 hours or more on the saw and create large piles of parts to be edgbanded, then you still had to run them on the PTP. The guy on the saw had to be good, and he couldnít really leave it, so you needed a guy to run the bander, drill shelves, etc. We now run the same amount or more of volume, about $20k a week in sales with 1 full time guy in the shop. My current shop person is a good guy but only has about 1 Ĺ years experience. You need a smart guy to make sure things are set up correctly but you need that either way with this kind of volume. The guy running the machine doesnít have to write code or anything like that. He just has to know how to change a router bit, and open a file on the computer.
My original plan was to keep the beam saw and nest only the parts that would need secondary machining. Within 2 days of being up and running with the nested base, I made the decision to eliminate the beam saw. The unit that I had had 12í x 12í capacity and took up a 23í x 23í footprint. 5 weeks later it was loaded on a truck! We combined this with other lean practices and were able to sublease 3,000 ft. of our space to someone else, reducing or rent by $1500 a month.
Tooling costs. We do all of the heavy cutting with a ĹĒ compression bit. These run about $50 a piece and about $15 per sharpening. We can get about 5 sharpenings out of a bit before it's no good. We usually get 40-75 sheets out of a tool before we need to change it.
When you are manually entering parts into a beam saw you can make minor changes to the list with a pencil. With the CNC it has to be right on the computer.
Material yield is different because you have such a wide kerf. I canít get standard 12 x 24 size out of a 4x8 panel. This takes a bit of creativity but when nesting in drawers we are using over 90% on jobs over 7 sheets. Smaller jobs donít give us quite the yield, but we can batch smaller jobs together.
Remakes. Parts are held in place by vacuum only, and occasionally you have them move. We have a remake rate of about .04 per sheet, a 10 sheet job might have over a hundred parts and we might have to re-run 2 drawer sides.
Material handling, unloading a nest with lots of parts can be time consuming. On a beam saw all of your like size item will be cut together giving you a little better organizing as it moves through the shop. Auto unload on a machine will more than pay for itself.
We generate a lot more sawdust than with a saw, changing bags is done a couple times a week.
Down time. I have owned this machine since 2004. Since then I have had two major issues that caused serious down time. The first was a breaking resistor that cost about $300 plus overnight shipping. The second wasnít really a machine issue. A wire bundle was held onto the machine with a zip tie that broke. The operator noticed it hanging but failed to do anything about it, and then it caught on a tab that pulled the wire connector apart. The repair process took a total of 4 days and to diagnose and I had to replace a $4,000 part, a Z axis drive. I have done all the servicing of the machine with the help from Biesse phone tech support.
Software has to be up to date. You canít skimp on the software, we originally ran the onboard software and programmed parts manually. After about 3 years, I realized I was wasting thousands in labor writing new programs for parts. We use Cabinet Vision, there are other that work as well, but you want it set up to be a full screen to machine package and you have to figure that expense in with the purchase of the machine.
Things I would do different
Knowing what I know now, I was too stubborn in the beginning. I tried to make the technology fit what I was doing instead of adapting to the technology. Be flexible, and donít get into ďThis is how we do it.Ē Talk to people that are already doing it and donít be afraid to change. The reps are a good source of info but, you have to watch out for them as they arenít in the shop doing it, they are trying to sell you a machine and make a commission. On software, donít pay for it all up front, have a retention of 30% that you release when it does all the stuff that the sale rep told you it would do and it's working.
If I was starting from scratch today, I would get a mid-sized machine with a good size drill head, and auto load/unload feature and a bigger dust collector. The midsize machines take up a lot less space that gives you lots of room for the automated loading. I would look at a couple of other software systems out there as well, although I am very happy with the Cabinet Vision package that I am running.
(Business and Management Forum)
From contributor L:
For your business I think you are right on. We are in a different business with no standard product, a job shop. We already had a good panel saw when we got our 1st router about 15 years ago. It was a 4x8 and not set up for nesting. The drill box couldn't reach the full width. We ran parts much like using a P2P. Our product mix started to change and a 5x10 router became available. Sold the 4x8 and went nested. We added an 8' CNC bore and insert machine and case clamp. The panel saw still gets used a fair amount but if it ever died it would not be replaced. We are currently considering a 2nd router, self load and unload. This time it will be a 5x12 with more drills. With a new customer that requires delivery in less than 2 weeks on custom case work, we are in need of having every process duplicated. It will end trying to run a partial 2nd shift. That job will also need to have a different case clamp, the interlocking beam type. When we are running typical box cases everything flows very nicely. A nest will produce somewhat more than 1 cabinet per sheet, depending on size of course. Boxes are melamine, fronts and finished ends are usually pre-lam. The only face drilling that is not done on the router is that for doweling the drawers. Our bore and insert machine was custom ordered with 3 drilling units to both dowel edges, dowel hole faces for drawers and drill for KDs. The software generates labels at the machine with a graphic of the part, what case it is for and what room the case goes in. We use conveyors to move parts and sort at the end of each machine based on the labels and where the part is going next. If all we were doing was simple boxes like kitchen cabinets this system would turn out a lot of kitchens. Needed: router, bander, bore and insert, case clamp, efficient way to move parts and software for what you make. I have been down a similar path to the questioner and could have saved time and money if he had told me his experience 15 years ago.
From contributor M:
This was a fiercely debated subject about 3 or 4 years ago on this forum. There are too many considerations to make an unconditional statement as to which production model is best. I have had successful shops using all the methods mentioned in the last 6 years. I went from 100% nested panel processing to slider/manual line boring machines and now beam saw and machine center. It all depends on your products, the market environment, your skills and experiences and much more.
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