Researching.....How could everyone be doing this?

[4cbdinc]

Hello. THis is my first post on this forum. I have to say that I like what shop bot is all about so far. I plan on purchasing a cnc machine in the very near future. I own a 2 man shop and this machine is basically going to be another set of hands to help out in the shop. I wont be running it for hardcore mass production (that is why i like this machine), but I want to be able to load a sheet and walk away and come back to a completely cut, bored, dadoes, cam holed, etc., etc. My main concern with this machine, and correct me if im wrong please, are all of you manually changing the tools for different cutters needed? I notcied on some of the past posts that people mentioned a tool changer for sale for approx $16,000.00 Is that the only option for a newbie. I cant make a tool changer when I have no real idea what the machine is apbout until I experience the trial and error period. I will be cutting up typical cabinet parts. So why would I want to load a 5mm bit and have that make all of the cuts? I dont want to spend time changing bits 3 times or whatever it would take to cut a typical cabinet end and I dont want to load a 5mm and wait while it make a bunch of passes to cut a dado. I am beginning to think that this machine isnt as versatle as it sounds unless you have the time to sit and wait for the machine to need a new bit. I Please fill me in because I am excited about this machine. I am interested in the prsaplha 5X10 machine.

[sailfl]

Jason,

These machine are capable of amazing things but they are machines. They require watching and input. You can purchase tool changers for less money than what you have been quoted. You can buy a machine or a number of machines that could process all the material from tree to the finished product but it would cost more than what a three man cabinet shop could afford. So like any situation you have trade offs. Even with a tool changer some one is going to have to baby sit the machine. But what you are going to find is that you will increase your production and produce a better product even if you have to have a baby sitter.

I would suggest that you see if you can find a person that owns a Shopbot in your area that cuts cabinets. Go visit them and see for your self the potential and the man power requirements of one of these amazing machines. If you are like most business, they thought that when they purchased a computer that they would use less people but what they found was they use the same number of people in the business and they also needed a computer person but that their bottom line increased because they were getting more business and they had more control over that new business.

I don't think you will be disappointed. Good luck..

[paul_z]

Jason,

I seldom leave my bot running unattended; however, if the cut is one I’ve made before, I usually work on something else in the shop while the bot cuts. I’d say it gives me an extra 0.8 person it the shop (which is a lot better than some of the people I’ve had in my shop).

You may not need as many bit changes as you are anticipating. There is no “law” that says you can’t make a 23/32 dado with a ¼ bit. It just takes multiple passes which usually takes much less time than changing a bit. It would also not disrupt whatever you are trying to do in parallel.

Look into the use of compression bits. They are both upspiral and down spiral. They make a finished cut on both sides of the material. They can be used to cut in a single pass or multiple passes. BAM Tools is a good source of highly cost effective compression bits.

Even if you have to fly somewhere to get your hands on a CNC machine before buying, take the trip. It is the best investment you’ll make, especially if you decide the machine isn’t right for you.

Wish you the best no matter what path you take,

Paul Z

[paul_z]

Clarification - compression bits are upspiral and down spiral in the same bit.

[jhicks]

Jason, for the longest time we ran 3/8" compression bits for 3/4" ply. veneers, prefinished ply, and mdf core to cut 3/8" dados. and cut outs. We ran 5mm holes for shelf pins and construction holes and thought it was pretty good having only to change bits once.
Then a fellow suggested he was running his entire part with 5mm holes, construction holes, dado's and 10mm/20mm holes for rafix knock down fittings with a single bit.
We tried it and its terriffic. Onsrud makes a 5mm bit they dont even recommend for wood or ply but it works well. The V flute seems best on melimine but the o flute is also nice. We get a minimum of 12 to 15 sheets per bit and often more and they can handle one sharpening vs a $90.00 compression plus 5mm drill bits, tool change over etc.
I know there will be folks who say "watch out for edge quality" or "You need a compression bit" but I can say our compression bits are sitting in a box for now and the 5mm is the bit of choice.
Be careful though, its cut depth is max .780 and it has a 6mm shank so dont drive those bores or cuts over .780"

[Gary Campbell]

Jason...
As your research has found, yes, toolchangers are expensive. I know we couldn't afford one in our 2 man shop. We use a spindle with a 3/8 mort comp bit to cut and dado. We use a drill to bore 5mm system and 1/8 assembly hole screws. We have to do a drill bit change, but it only takes a few seconds. We use 3,5 and 10 mm boring bits (70mm long)set in a boring machine chuck that are all indexed to exactly the same length. The boring machine chucks (with 10mm threaded end) are just chucked into the air drill chuck as far as they go.

IF I won the lotto... I would add a second spindle and another drill.(4 are options with a dual Z) Then I could have 2 router bits and 2 drill bits.(or 4) I would probably machine an adapter that screws the boring tool holder to the air drill shaft. I can hardly imagine a cabinet panel that I couldn't cut with that configuration.
Gary

[harold_weber]

Jason, if you are convinced you will need a tool changer, and if you are prepared to deal with the additional programming needed to support it, then call Haze Avery. You are VERY fortunate in that he's less than 20 miles from your shop. See midwestrapidtool.com

Haze gave a demonstation of his tool changer at John Forney's 2007 Ohio camp, and you can see photos of the toolchanger on John's machine at: flickr.com/photos/campshopbot

Since its based on a PC7518, its not as powerful or durable as the $16000 tool changer, but remember you're less than 20 miles from the manufacturer..............

[ryan_slaback]

Jason,
I included a link to the system I believe Harold is talking about. If I were to need to change tools quickly I would go with this system. If you made up a jig so that the exposed length of each tool was the same you would not need to rezero the length. You could either use the system including the whole changer the company has put together, or just get the router with the drawbar and still manually change tools but at a time cost of 10 seconds rather than 5 minutes.

http://www.midwestrapidtool.com/index.htm

[thewoodcrafter]

Jason,
I cut cabinet parts with my PRT Alpha. I would suggest you forget about a PC router with a tool changer. You will want a spindle for any speed. I ordered a second Z for my machine. I will use it for drilling 5mm holes with a PC router and if my spindle goes down for repair I can still cut with the machine.
I now use a 3/8" for cutting face framed cabinets and a 1/4" bit for frameless and will be using a second Z for the holes. So you really only need 2 bits to produce cabinet parts.

[harryball]

Single machine with one larger spindle like the 4HP HSD and a smaller 2.2HP spindle rocks in a cabinet shop. You can install your 3/8" compression cutter in the larger spindle and a 1/4" or 5mm etc... whatever you plan for your drilled hole sizes to be and pretty much eliminate the bit changing routine.

Basically, get your project to take 2 bits, run 2 spindles and you've got it.

Robert

[jeffreymcgrew]

OK, so while that PC bit changer is completely awesome, it comes along right when we're thinking of swapping up to a spindle. Are there any somewhat-inexpensive options like that for a spindle? Can we convince those guys to make one? ;-)

All the bit changers I've seen for a spindle cost more than our whole 'bot.

[gerald_martin]

My machine has a Colombo 3 HP spindle with ER25 collets. I'd be very interested in this the midwest rapid tool - tool changer concept for this spindle.

[thewoodcrafter]

A spindle made for a tool changer has a hollow shaft that has a grab bar that runs down and can grip the tool holder. These spindles are available I think in 5HP and up. I priced them at the last show in Las Vegas and I seem to remember over $5000 just for the spindle. Add to that the tool holders, rack to hold the tools, air powered setup to grab the tools and you have a tool changer. Not cheap.
When I first got my ShopBot I too thought I needed a tool changer. But if you design your jobs around a 1/4" or 3/8" bit I find I really don't have to have one.
I would like to have one but the expense doesn't warrant it.

[jamesgilliam]

Jason, I am a one man shop and cut various things with my PRT. When I first had the Bot I too usually watched over it's progress while cutting. These days I get it running and then work on something else while it works, usually close enough to hear if something doesn't sound right. When I am doing cabinets I plan them for using a 1/4" bit for holes, dados, and the cutout of the finished pieces. Since I also do carved signs and the files sometimes have a long run time I have left the machine alone to go to lunch and everything has been great so far.

[henrik_o]

quote:My main concern with this machine, and correct me if im wrong please, are all of you manually changing the tools for different cutters needed?
No. You have the option of two router bits loaded into router(s)/spindle(s), plus up to two pneumatic drills (I think). Look at the Dual Z and Air Drill options in the price list.

Realistically speaking, by being careful about cabinet construction, you should almost always be able to do common cabinet parts efficiently with one router bit (cut out and dados etc) plus one drill bit. For this scenario, a one axis shopbot plus an air drill is a very economical way to do rational machining.

If you need more than one router bit and one drill bit, I think the first step is to sit down and think through the cabinet construction. Do you really need more than that? Can you change the construction to be more bit efficient?

If you do need more than 1 router + 1 drill, then you have to purchase a Dual Z axis, the spindle/router to go with it, and also possibly buy a wider shopbot, since the dual Z steals space along the Y axis. Now we are beginning to talk real money: it's still far less expensive than a proper spindle toolchanger, but it's not pocket change.

To put things into perspective, I have a shopbot with a Dual Z. I have not put anything into it, yet. I will do so, and I feel great about having it, but so far there's been no real need. When I researched the shopbot, I was thinking like you do, about the specific capabilities of the machine. Having had one for half a year, I will say that most of my focus these days is not so much on the machine but everything around it.

How much time does it take to change a bit, re-zero and load a file? A minute, tops. Consider all the things that go into cnc machining besides the actual machining: you need to be able to load panels and evacuate parts efficiently. You need to mark, stack and transport away finished parts to the next station. You have to dispose of scrap and clean the machining table before you load the next panel, and so on and so forth.

These are the things that really take time, not changing a bit. The good news are that there's plenty of good and low cost equipment to help you with all of this.

What we should be interested about is not machine cycles per se (the time from starting the first program to finishing the last), we should look at processing cycles (the time from loading one panel until loading the next). Yes, the machine cycle is one part of that, but just one part.

If we are rational, we look at the whole processing cycle and we attack the parts where we can get the most bang for our buck. It is not good economics to buy a toolchanger system that costs us $15,000 to save thirty seconds in the whole cycle, if we could spend $300 to buy wall mounted sorting racks that saves us a minute. Go for the low hanging fruit first. As you progress, you will get a worse money/time exchange ratio, and at one point a toolchanger system may be the most rational next choice, but if so it should be because you have gone through the better investments.

[wberminio]

Henrik

You've have hit the nail on the head

Erminio

[ryan_slaback]

I realize I am playing Devil's advocate here but this is an actual experience of mine. I know the rest of you swear bit changes take a maximum of a minute and for you they very well might. However, I have had them take as much as 14 hours. I very much like to start the router and let it cut while I am on my way home from school. If a changer was an option it would be possible to come in the next morning and have the whole system cut for me. Not partially done. Perhaps the other thing some of you fail to consider is that not everyone can drop what they are doing to change a bit. In my case I might be in the middle of a class or speaking with a student. In the case of a small shop, they might be on the phone with a client or figuring specs for the next job.

I will now step off my soapbox. It just really gets my goat when everyone tries to convince people a changer is a waste of money because bit changes take "a minute or less."

[elcruisr]

The need for a changer should be based on the work being done. I now have over 200,000 parts cut on my 'bot and see no need for a tool changer for the work that I do. A great deal can be accomplished using area clearance cutting strategies, etc. However if I was in a different situation requiring constant tool changes than it would be a different matter. The question should be will a tool changer make me more profitable? Look at all the cutting strategies and tooling tricks versus a tool changer and run the numbers. Then decide.

As for allowing ANY CNC machine to run with no one in the shop, well, you're braver than I am. In six years I've had 3 material and spoilboard fires. This is far from unique to ShopBots. It happens all over the industry. Hitting a piece of trash in a panel resulting in a dulled tool. Increased friction in wood dust and a fire starts! Vacuum hold down fans the flames and it spreads pretty fast. I keep a 15 lb CO2 extinguisher at the end of my 'bot. I know of some shops with big iron that keep 5 gal buckets of water handy.

[evan]

I'll second what Eric has said. Leaving a machine unattended is unwise and unsafe. That doesn't mean I'm not getting other work accomplished while the machine is running but I'm always within hearing distance and seldom out of sight.
As for a tool changer sure it would be nice, but having designed cabinets for and operated a Holzer with an eight bit tool changer, and a six head drill block I can say that 90% of the time only two bits where used; a 3/8" comp. and 5mm drill bit. The other bits that got some use were the 35mm for hinge boring, the 2-1/2" spoil board surfacing bit, and a 1/2" for cutting counter tops. The hinge boring could be accomplished by pocketing with a 3/8." The point being I never designed a cabinet that used all eight bits in the tool changer. There was a sign I designed that used 5 different bits once but... That being said it just doesn't take that long to cut a sheet when cutting cabinet parts, it almost takes the same amount of time to unload, clean off the spoil board, and load a new sheet on, which brings us back to everything Henrik so eloquently stated.
Just my two cents.