ShopBot and Cutting Pywood

[imsa]

Just now getting into the CNC woodworking field and have a question. I’ll be ordering a PRS standard 96 in the near future and am curious how well it works for cutting plywood. What I’m getting at is I also need a sliding table saw for cutting down and shaping 4 x 8 veneered plywood sheets and if the ShopBot can leave a clean cut and clean dados with no tear-out, I see no need for a sliding table saw. I assume the quality of the cut would depend on the quality of the router bits and cutters. Am I on the right track?


Thanks


Terry

[myxpykalix]

Well that is one of the components and if you want sharp high quality bits that are reasonably priced check out: www.centuriontools.com (http://www.centuriontools.com) call Fred

[harryball]

Quality sharp bits, look at compression spirals. They will leave a clean finish on top and bottom. I don't cut prefinished plywood but I do cut a lot of ACX and dados in them. My workhorse bit is a mortise style cutting bit.

Also, visit someone and witness cutting in person.

/RB

[thewoodcrafter]

You will not need that expensive slider.
And I would buy an Alpha if I were you.
Way faster and stronger.

[imsa]

Thanks for the help. I didn't think I would need a sliding table saw with the ShopBot but wanted to make sure. Since it will be a while before I will be doing any serious production work, I'm going to start with the Standard and see if I have to upgrade at a later date.

Terry

[myxpykalix]

My advice Terry would be that if you were thinking about also getting a sliding tablesaw then you could afford the Alpha now. The reasoning is that after you get your bot and start working with it, the time and effort it will take to do the upgrade and the downtime may later on, after you are going full tilt, come back to bite you. If it is a matter of money than thats a different story.

[wberminio]

Terry
I also make custom cabinets
I sold my slider to make room for my PRS Standard
So far no regrets

Erminio

[bws]

A sliding table saw is a really nice piece of equipment to have and use. It too is a shop space eater.. With a sliding table saw you can set the fence throw a piece of ply on it and cut. It takes 10 seconds to set the fence and 30 seconds to cut the piece. You get nice clean accurate edges in both directions. This could be one of a kind cut, or many repeative cuts over many pieces of plywood.

Using a CNC machine is similar to a rocket launch. You have to program it to do cuts each and every time. The plywood has to be registered along a straignt line that the router or spindle will follow, or you could just cut it square (or any other shape) if you don;t want to follow the edge. Next, the piece has to be held down to the table using a vacuum system or screws or clamps, it cannot move or you will ruin the cut. Next the bit has to be selected, if you want both edges clean, then you probably would use a compression bit. After the bit is installed, you have to zzero it. Now, you are ready to cut.

If this is going to be a production run using the same cuts over and over, you probably want to use the bot. If the cuts are really complicated or strange angles, it may be easier to program and use the bot. If you are nesting parts, definately use the bot.

When you get your bot, there will be a "honeymoon" period. You will be using it to cut almost everything. It's fun to program and there is a degree of satisfaction knowning you programmed it and it works. This is similar to when my 5 year old boy (many, many years ago) learned about hammers....suddenly, everything needed hammer'n.

The bot is a wonderful and versatile tool, but just because you CAN do somethng, doesn't mean you should. For example, I have to make 78 arches for interior doors for a hotel chain. These arches have a complicated moulding profile. Yes, I can do them on the CNC, but you have to make about 6 bit changes for every arch ..(not to mention sanding down the fine ridge lines when each arch is completed). It's more efficient to make the basic arch (6" x 32" x 2" Mahogany) on the bot then use the W&H moulding machine to complete the moulds.

The moral of the story is, use each piece of your equipment to it's best advantage.
If you can afford both the bot and the slider, you may want to re-think your situation.
That's my 2 cents.
Jim

[wberminio]

I think my answer was a little too simple.I would have kept my slider if I had the room.I do have
a Hawi Vertical Panel saw with 4HP motor and scoring blade(which I still use).I also have a W&H moulding machine.I don't hand cut my templates any more(hours & hours of Shaping and smoothing before cutting mouldings).My moral is the same as James-"use each piece of your equipment to it's best advantage.If you can afford both the bot and the slider, you may want to re-think your situation." I will add -the bigger the shop,the more I will fill it!

Erminio

[jhicks]

Terry, we run our custom signs and other interesting projects on our 2003 vintage 5x10 PRT and have jumped into a lot of cabinet and closet work over the past 5 months. On the closets and the cabinets we cut several materials. Prefinished maple ply, 13 ply birch, "platform ply" melamine,unfinished veneers and MDF.
We have a home made vac hold down and design in cad for cabinets. We import the cad dwg files into router cad but thats another story on software you choose.
In the end we have used 3/8" compression bits plus 5mm hole drilling bits until we decided to just use 5mm bits for all cuts.
So we now have gone through about 25 bits with an average of 20 to 25 sheets per bit at around $20.00 to $29.00/ bit.
We decided that the ease of NO BIT changes offset the effort to change even though speed, depth are a bit slower.
We set program to run all dados, 32mm system/5mm shelf and slide holes, and cut outs of sides, strechers, and any other parts with one cut file and one bit. A 5mm onsrud two fulte straight v flute or O flute. Haven't seen any real difference except one is cheaper than the other. We cut to a max of .780 deep (max bit cel is about .790")and run at 160 IPM, 13000rpm on a 5 hp spindle. Drill plunge is 35 to 40 IPM, cut is 3 passes but know folks doing it in 2.
We dont even rezero the Z between sheets like one would with a bit change.
There are no issues with edge cut quality on top or bottom surfaces as long as you monitor and surface your spoil board and keep a sharp bit. Even that isn't really much of an issue as we have really overworked some spoil boards with surprisingly effective results. There is an issue with through hole break out on the bottoms of sheets, especially with melamine but usually they are construction holes for assembly at the edges or sides and non issues since screws are going in them anyway.
I'm sure an alpha will be faster and know of folks running at 320IM with same bits and 2 passes on cut through with other brand more industrial grade machines.
At our speeds we see an average run time of 30 to 45 minutes per sheet depending on number of holes and parts. Time to mark parts, remove sheet, dust table, reload and restart runs 5 to 8 minutes max. No bit change saves or new files to open saves about 3 to 5 minutes plus leaves the operator on other tasks like disposing of scrap , edgebanding, assembling carcasses,or other tasks.

So the final determination of organizing cut list for yield, table saw set up, cut, reset fence/cut, handle/move parts and sheets, line bore set up, line bore, handle/move parts, mark, handle/move parts, stack in between moves vs stack multiple sheets, load, run, mark, clean table, reload tells us we can't beat the bot with conventional tools.

One must remember that the conventional method requires constant intelligent decisions by the cabinet maker and multiple set ups, fence setting, line boring setting, as well as parts being handled many times between the moves.

The bot leaves us 60%+ of the operators time to do other operations like edgebanding and/or carcass construction, door/hinge and/or face frame mountings as the next sheet is cutting.

In effect by generating ready to cut files they can load well nested/high yield design files and go, one gains productive time equal to 70% of an additional lesser skilled/paid employee plus perhaps 30% over conventional methods and the final cnc time which we estimate to be at least 30% more efficient to begin with based the pay differential alone.

Finally this process gets the parts made to exact design and carcasses assembled before the skilled cabinet maker ever sees it, they can then focus on more precise trim and key assembly fit issues rather than the lower level operations.

Benefit summary.
Fewer skilled cabinet makers needed for same or greater output at lower coat.

Less space and fewer tools required.

Single set up for all parts over many sheets or even days.

70% to 80% gain in time/labor cost to cut parts with lower skill level operator cost for cnc.ie he only uses 20% to 30% of his time to man the machine.

30% + reduction in labor cost on cut and handle based on equal time of cabinet maker vs lower skill pay employee if all they did was watch the machine run.

Added output volume/lower cost by effective use of lower skill/pay operator time to edge band/assemble carcasses as machine fabricates parts.

Single material layout and fab set up vs multiple handling operations and set ups by skilled cabinet maker.


Hope that helps answer your question.

[carlhopkins]

Hi fellows,
I just bought a used 5x10 alpha, 3hp spindle. Still setting the vac hold down system up. I am thinking about using the 5mm bit setup as well. I build custom cabinets and have a 1-1/2 man shop. I understand from working with cnc in the past that speed is not a reason to use cnc. But if I could get the table saw to work without me well that would be just great. yes the cnc will require some input but just as you are saying use the equipment to your own benifit.
Good luck, Carl

[thewoodcrafter]

A lot of good info here Terry.
I would still highly recommend the Alpha.
An Alpha can cut at about 3 times the speed as a standard (with good vacuum hold down)
And a spindle of at least 3HP, 5HP would be better.
I have a 3HP spindle and a second Z (PC for drilling)
Sometimes I wish I had a 5HP spindle.

[bws]

I, of course, agree with Jerry. If you are going to do multiple operations on each piece, then definately go for the bot. For every operation you do by hand, you increase the chance of a mistake in measuring or setting something. Before the CNC I used to make jigs for almost everything for that same reason, especially if I was making multiple copies of each piece. After the second one, your mine starts wandering as you go through the motions. The jigs removed much of the setting and measuring, but not the boredom.
Jerry is using his machine to its best advantage. Each piece is going to be identical to the original... the boredom, safety, setup and measurement factors are removed.
This is exactly why you should be using a CNC machine.
Still, if you are doing one-of-a-kind, you have to weigh in the programming/setup time vs just doing it on conventional equipment.

[imsa]

Wow! I’m overwhelmed at the depth of knowledge in the above posts. My purpose for getting a ShoBott is for inlay work, extremely detailed carvings, and other finely detailed tasks. My question was, and it’s been answered superbly, if I could basically use a ShopBott in place of a sliding table saw. I should have included additional information such as I am not a production shop and I’m not going to be doing production cabinet work or any other kind of production work using plywood or any other material. I will on occasion need to make long sweeping cuts that could be done with a jigsaw (too big and awkward for a band saw) but the ShopBott I am thinking would produce a cleaner and more accurate cut. I’m not concerned about speed as I will be cutting no more than 5-6 sheets of plywood a week but cut finish and accuracy is a must. Any square cuts I may need with plywood can be done quickly with my SawStop.
By the way, what is a spoil board?

Thanks

Terry

[chiloquinruss]

A spoilboard is the underlayment piece under your work piece. As your router 'cuts' through the finished material it will actually cut into the 'spoilboard' and NOT into your ShopBot. Russ

[beacon14]

I worked my way gradually from using the SB mostly to drill holes in panels I had already cut out on the table saw to now I put the whole sheet on the ShopBot and off come parts that need only edgebanding. Hardware holes, wire access holes, access panels, curved and angled parts, nested parts, dados, rabbets, etc are all done at the same time that the parts are cut out of the sheet - while I am doing something else in the shop. No way would I go back to cutting sheets of plywood on the tablesaw. (I used to have a slider, although I never had both the slider and the Shopbot at the same time; I'd still replace my ShopBot before buying another slider.) I use a single flute compression bit from routerbits.com which cost in the neighborhood of $1/sheet, similar to the cost of a good quality blade/scoring blade set plus repeated sharpenings. Yes the design and programming time are not insignificant but I do that in the evenings while sitting comfortably at my computer, the old way I still had to generate cutlists then figure the most efficient way to cut the parts out of the sheets on the table saw, then use the line borer, then cut the notches/dados/rabbets, then drill access holes by hand, you get the picture. I also vote for the Alpha for heavy sheet goods production although for 5-6 sheets a week a Standard is probably fine. I have a 2.2 HP spindle and am very happy with it. I can cut through 3/4" material in a single pass at 5-6 inches per second although I use a two-pass method to ensure proper hold-down as I do not have a monster vacuum motor. If I need a few 3" rips of plywood then yes the tablesaw is quicker and easier but for almost any other parts including simple rectangles I go with the Shopbot.

[imsa]

Thanks Russ

Terry

[dingenis]

hi jerry,
thanks for putting this information on "paper",and sharing with others.
i will be using your text to explain to partners to explain production decisions.(if you dont mind, your name and address wil be included).
Any info(like the essay you wrote on production decisions) on logistics of material etc.?


thanks
dingenis

[gene]

Terry
For cutting long sweeping cuts the bot will do great. if you are cutting 3000 shelves the slider will cut great . James said it best as i ever seen , each tool has its purpose so BUT THEM ALL...YOU can never have too many toys...

[ckurak]

Jerry,

Do you have the Onsrud part numbers for those two 5mm bits, please? I tried searching for them on their website, but could not find them.

Thanks,

Charles

[gundog]

Terry,
You could buy the Bot and one of these panel saws for much less and the panel saw will not take up much room. I have this model and it works great for cutting down full sheets. I bought my panel saw used for $675 on CL. My saw came with extensions for full sheets I have it leaned up against a work bench and it virtually uses about 18" of space behind the bench and it has rollers so it can be moved easily.
Mike

http://www.panelsaw.com/products_saws_c4.htm

[jhicks]

Charles, bit number from Leitz is 737310021, Onsrud number is 56-431 for the O flute and 56-451 for the V flute. we see no significatt difference and go with the lower cost.

Dingenis, feel free to use whatever info you find helpful. Thats whats its out there for. Not sure what yor are asking by "Any info(like the essay you wrote on production decisions) on logistics of material etc.? " but if you can clarify your question, I'll do my best to help where I can.
As usual my opinions are worth exactly what you pay for them so always double check your facts and goals to modify any suggestions to your best advantage.

[ckurak]

Jerry,

Thank you!

Charles