Why CNC was a mistake - Or how I learned to love the table saw

[John Coloccia]

Here are my thoughts after living with a CNC machine and no table saw for 2 years:

1) The bandsaw IS an excellent replacement for a table saw if you're not dealing with lots of sheet goods or making lots of cabinets and square things like that. For furniture work (or guitar work, as I'm doing), these initial cuts are not intended to give the final finish, and it works out very well.

2) The bandsaw is NOT a great replacement for a table saw if you have to make lots of jigs. Jigs really require very straight edges, if only to have a reference edge. There are lots of fiddly little parts that go along with making jigs. These also have to be pretty square and accurate. The table saw is simply more convenient and more accurate for this kind of work.

3) *IF* you're a busy shop, and you can deal with spending a lot of time on the CNC, OR if you're a not so busy shop doing simple things such as signs, a CNC machine can be an excellent addition to the shop. It's not a great tablesaw replacement if you're making lots of one off jigs and things like that. The CAD work is easy...running the machine is easy. That's not the problem. Work holding is the problem. I found myself spending more time making jigs who's only purpose is to hold the parts to make my other jigs. If I was doing a production run, it's not a big deal, but I don't do huge production runs. The process of making the work-holding fixtures can get so time consuming and wasteful that it completely dwarfed the process of actually building things.4

4) Work holding fixtures are a pain

5) Work Holding fixtures are a pain

6) Time time time time...large CHUNKS of time. It's not a big deal if you can get a solid 5 hours to get a task done. As it it, especially with the new twins, I have no such luxury. I'm assuming that a lot of hobbyists, and pros like me, are in the same boat. There is limited, sporadic, shop time because you have to do other things. In my case, I'm a one man show so I have to do all of the business side of things, customer service, taking care of the kids, and family. CNC is simply a bad solution if you need to be able to work in 15 or 30 minute chunks. In order to be effective, I need to be able to get something done in short bursts, and CNC works in the complete opposite way. To be effective with CNC, you need to be able to do a task from start to finish. This one thing, more than anything else, has made CNC very difficult to deal with. It's something that's never talked about, but I think this is the killer for the small shop or hobbyist. Again, not a big deal if you're just doing things like signs and simple things like that. They require very little interaction. If you're doing complex things where you need to re-fixture things multiple times, change bits, do tool touch-offs and things like that, your choices are very limited. Either you do very complex fixturing and indexing, or you dedicate a large chunk of time to see your processing through to completion.

I'm in the process of selling off the CNC and bringing a table saw back into the shop. While it makes some things more difficult, and requires an awful lot more hand work, the fact is that I can actually accomplish my tasks a few minutes at a time. In theory, the CNC would blow me away in terms of productivity, but if it sits unused because I can't get my large chunks of time lined up, then as a practical matter hand work is far and away the winner.

Anyhow, these are my thoughts.

[Ryan Mooney]

Interesting perspective John.

I was wondering how it would work out when you made the switch, thanks for following up. The jig point is a good one and especially relevant for what you do.

I like the idea of a cnc but it did seem like it would be best for batch jobs where you can crank a whole lot of the same through it (and as a hobbiest I don't do a whole lot of those either). Nice to have some validation (although I still sort of want a CNC just because :D)

[Art Mann]

I've had a modest but fully equipped cabinet shop for a long time. When I bought a CNC router, it never occurred to me to use it to replace any of my other machines. I was strictly looking for new capabilities. I use it to do high value work carving signs, plaques and boxes. I have seen people on the CNC router forums describe their struggles to get their machine to replace a table saw, router table or even a jointer. It just doesn't work out that well unless you are making a lot of the same thing and can amortize programming and setup time over many products.

[John Coloccia]

I've had a modest but fully equipped cabinet shop for a long time. When I bought a CNC router, it never occurred to me to use it to replace any of my other machines. I was strictly looking for new capabilities. I use it to do high value work carving signs, plaques and boxes. I have seen people on the CNC router forums describe their struggles to get their machine to replace a table saw, router table or even a jointer. It just doesn't work out that well unless you are making a lot of the same thing and can amortize programming and setup time over many products.

So what ended up happening is this:

I didn't really want a table saw replacement. For a lot of what I do, I really just don't need or use a table saw. However, the stuff that I SHOULD have been doing on the CNC I started doing by hand, because it just seemed simpler than having to create a new CNC fixture. OK, well now that I'm doing it by hand, it would be convenient to have some jigs to do that with. Well shoot, it's a lot easier to make jigs with a table saw than to make them by hand OR on the CNC.

So here I am. Honestly, if I had the room I'd keep the CNC. For the things I have it doing, it does it very well. I just wasn't able to get over the hump because for some things, it's just not working out for the way I work these days. I suspect it doesn't work the way most hobbyists need it to work either.

I actually have a vague idea for a precision router platform that I think will work much much better for me, and maybe for others too. Maybe I'll have it built sometime next year. We'll see :)

Moving forward, I'll probably design some of the more fiddly jigs that I need, and maybe draw it in my cad program and farm it out to any one of a number of friends that are using CNC in their shop. That's a nice compromise. I may even have them whip up some basic parts for me.

[Peter Quinn]

Interesting observations John. I know of a few small cabinet shops that have taken the leap to CNC and say it has opened up a world of capacity. The shop I'm at is considering it and I wonder what changes that might bring, for better and worse. They start taking on jobs they would have passed on previously because they can, doing work for other shops making blanks, templates, stuff with repetitive cuts in sheet goods or curved cutouts like sinks in corian. Of course most cabinets are heavy in plywood, and most are just flat planes jointed together at right angles, so they aren't really much different than signs. I could see a 1 man shop with a very specific product like guitars having a very different production model. I'm also acutely aware of the demands of parents with young children and what that does to your time constraints. I took most of a year off when after my son was born, stay at home dad until he was a little older and my wife and I found a care situation we were comfortable with. I was crippled at first, programmed to work in long segments of time, for instance do all the doors for a kitchen from milling to shaping, or cut half a lift of plywood, dado, etc. Suddenly I had 1/2 hour if I'm lucky, here and there throughout the day, each time i walk back into the shop I had to spend 15 minutes remembering what I was doing. That evolved, positive change for me, made me far more flexible as far as time management.

I could never see myself having no table saw. I could see not having a cabinet saw with 60" rails and full out feed table, but at least a good small variety saw always seems valuable to me. I'm just finishing up a large curve in plan entry set, piles and piles of jigs, all made by hand with routers, trammels and a table saw. Took so much time.....I'm at the opposite end of the spectrum wondering if a CNC would not have expedited the process. Of course the guy doing the CAD and CNC programming would have to be woking closely with the guy doing the building when they are not the same guy. Is it quicker to explain to somebody else what a tool has to do so they can have a machine fabricate my parts or just make the thing straight out myself?

[Larry Edgerton]

Thanks for your thoughts John. I have wondered how it would fit for me and don't think I can justify he cost. You have kind of confirmed that for me. Besides, a computer guru I am not....

Larry

[John Coloccia]

Interesting observations John. I know of a few small cabinet shops that have taken the leap to CNC and say it has opened up a world of capacity. The shop I'm at is considering it and I wonder what changes that might bring, for better and worse. They start taking on jobs they would have passed on previously because they can, doing work for other shops making blanks, templates, stuff with repetitive cuts in sheet goods or curved cutouts like sinks in corian. Of course most cabinets are heavy in plywood, and most are just flat planes jointed together at right angles, so they aren't really much different than signs. I could see a 1 man shop with a very specific product like guitars having a very different production model. I'm also acutely aware of the demands of parents with young children and what that does to your time constraints. I took most of a year off when after my son was born, stay at home dad until he was a little older and my wife and I found a care situation we were comfortable with. I was crippled at first, programmed to work in long segments of time, for instance do all the doors for a kitchen from milling to shaping, or cut half a lift of plywood, dado, etc. Suddenly I had 1/2 hour if I'm lucky, here and there throughout the day, each time i walk back into the shop I had to spend 15 minutes remembering what I was doing. That evolved, positive change for me, made me far more flexible as far as time management.

I could never see myself having no table saw. I could see not having a cabinet saw with 60" rails and full out feed table, but at least a good small variety saw always seems valuable to me. I'm just finishing up a large curve in plan entry set, piles and piles of jigs, all made by hand with routers, trammels and a table saw. Took so much time.....I'm at the opposite end of the spectrum wondering if a CNC would not have expedited the process. Of course the guy doing the CAD and CNC programming would have to be woking closely with the guy doing the building when they are not the same guy. Is it quicker to explain to somebody else what a tool has to do so they can have a machine fabricate my parts or just make the thing straight out myself?

A larger shop, with a larger CNC machine and vacuum table, you can do really well just tossing down a sheet of plywood, maybe doing a tool change or two on your automated tool changer, and out pops a cut list with lots of holes drilled. I think it really excels in that environment for the woodworker, because it takes nothing to toss down a sheet of something, turn on the vacuum, and go. When you start dealing with things other than sheet goods, or if you're in an environment where you can't get a the huge vacuums you need for large vacuum tables, now things get far more interesting. It's much closer to metal working than woodworking, actually. Work holding can be a royal PITA for machinists too, CNC or not. Sometimes it turns into a little puzzle of exactly what order you machine something in so that you don't blow away the nice straight edges you need to hold things for the next step. Where do you measure from? Add in having to account for wood movement and resting periods over several days, and now you have a REAL puzzle. It's very solvable, but at a certain point it just becomes easier to whittle by hand if you're not making the same exact model over...and over...and over...and over. :) With sheet goods....or flat work, anyhow...a good vacuum table, and lots of this goes away and it can be a huge time saver.

[Mike Heidrick]

What CNC machine do you have?

You can make your own vacuum table pretty easily depending on your machine design.

I use one, plus T track in my table and also just screw work to the table and also use a lot of tabs.

[Jerome Stanek]

CNC for a small cabinet shop are really nice to have I is like having an extra person that won't talk back and do what you want. You can load a sheet on it start it and let it go while you start to assemble another cabinet. doing 2 things at once.

[John Coloccia]

BTW, some may be wondering why I'm not considering a European combo machine. I am, actually. The thing is that I'm planning a move in the next 6 months, hopefully, and without knowing exactly what my new shop space looks like, I question the ability to effectively use a slider, or possibly even get it into the shop. One thing very attractive about a slider is the ability to straight line rip. I also like the ability to make very accurate crosscuts. Then again, it's not like I can't just make a jig to straight line rip on a table saw.

Anyhow, I have some thinking to do here. I have to really think about the way I work and if a slider will work for me or against me in the long run.