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View Full Version : Choosing a Shopbot: Points to Consider



jemelby
09-12-2007, 03:57 AM
I have concluded that my years-old conclusion that "Shopbot is the best choice in low-end CNC routers" is still valid. There's lots of great new stuff out there, but SB is still ahead of the crowd.

Here's how I intend to use my SB: To be honest, I really just want one to play with. I tell myself all kinds of lies about how I'll do custom work locally. Then I'll start a web business for all manner of doo-dads, toys, and the like. And let's not forget how much money I will be able to save buy doing all the mill work for the house I will eventually build! You get the picture. I am sure many of you have been in the same boat at one point. The reality is that I will HAVE to use the SB in some manner for profit.

I am very well inclined towards all things mechanical. I have also been designing all my wood projects in AutoCAD for 4-5 years. One of my biggest failings in the past has been "designing as I go." I will have an idea, and just start building. I could get away with this because I am very good at visualizing the final product, and how it will go together. I paid for it, though, with wasted time in the shop while I figured things out. In the past 4-5 years, I have gone into the shop with a cradle-to-grave plan in AutoCAD, and it has increased my efficiency considerably. It's also done away with the occasional wasted piece of wood.

It now becomes a question of "What model?" One would not expect the marketing department at SB to say "The Alpha is GREAT, and the standard is not-so-great." So it's left to me to ferret out in what areas the standard falls short of the Alpha.

I read through many posts here, and did an extensive google search. It seems to come down to motors and step drives when comparing the Alpha to the Standard. Speed is always nice, but considering this machine will be in a one-man-shop (maybe two-man, at the most), speed isn't so critical. As long as the machine will run unattended, there's always plenty to do while waiting. Accuracy is a more important concern. I tend to be a bit fastidious about accuracy. I keep a 1/64" graduated 6" steel ruler in my shop apron, as well as a digital dial caliper (is that an oxymoron?). I generally plane board to within 1/128", and have been know run the boards through 3 times without adjusting the depth (just to shave those uneven parts exactly). I am concerned that I will be disatisfied with the accuracy of the Standard, and would forever wish I had started with the Alpha. this is not the most sound reasoning, but there it is. Alpha wins over standard.

As to the spindle: I have read in several places how folks were amazed when upgrading from a router to a spindle. I've decided to forego the amazement stage and just start with the spindle. I've burned up two PC routers over the years: One in a table, and one used only free hand. I can only imagine that the life of a router in a SB would be hell. I am slso familiar with run-out. I actually have the top of my router motors marked with the direction for which they are most prone to run-out, and try to keep that mark 0° or 180° to the direction of travel. That leaves a choice. I think the 4 HP HSD would do nicely. I am figuring that the more expensive Columbo spindles are better in terms of speed and torque. I am assuming there is not an accuracy difference between the HDS and Columbo spindles. I might also consider the 2.2 HP HSD after figuring what 3 phase juice will cost to wire. The single and three phase 2.2 HP spindles are the same price, while the single phase 4 HP is a couple hundred dollars more.

96x48x8 is the chosen table size. I'd like to be able to mount a full sheet, and space should not be a factor (shop is in an aircraft hangar). For a 10% price difference, I'll go with the 96" over the 48". I also can not imagine a need for the 14" hight over the 8". If I have a deep piece of stock, or want to endmill a piece, I can always rig up a way of letting the stock hang below the table, right?

So there's my reasoning: 96x48x8 Alpha w/4 HP HDS. Should be around $15,200+shipping Next, I'll have to determine my software needs. I truely think that is something I can upgrade later. I should be just fine with AutoCAD and the stuff that ships with the SB.

I formally wecome and invite any and all to punch holes in my reasoning, or to help feed my delusion. At the end of the day, I really don't have a clue what I'm talking about. I still have to get out and see one in action. I might even wait until after the Atlanta IWF. Should be a great show this year!
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fleinbach
09-12-2007, 07:44 AM
James,

When I read your statement "designing as I go." it surely hit home. I have been doing this all my life. Right know around my own house I have several large projects I've been working on for the past 3 years and the main reason they are not done is because I start with an idea and begin building and come up with something better.

I have an 18' oval shaped gazebo I started 3 years ago and for the past 9 months have been working on the facia design. I thought I was going to put it on in January but here I am still changing the design.


Anyway that dosen't answer any questions for you but I believe you are making a good choice. I'm not sure if you considerd the 3Hp columbo as it is 3 phase with an inverter so you can run it on standars 220v. That is what I use and love the way it preforms not to mention how quiet it is.

I believe for the majority of people 8" Z depth is plenty suficiant and as you say you can make cuts on thicker material or edges at one end of the table.

rcnewcomb
09-12-2007, 08:51 AM
I would recommend buying the V-Carve Pro software. Even if you continue to design in AutoCAD, the ability to V-Carve your designs makes it worth the price.

Also, download the free 3D Machinist software from VectorArt3D along with one of the free patterns, and see if the 3D carving bug bites you.

bill1
09-12-2007, 09:18 AM
I surely agree with the above posts and if you do download the free 3D Machinist software from http://www.vectorart3d.com/machinist_free/ the 3D carving bug will defiantly bite you.

knight_toolworks
09-12-2007, 11:19 AM
v carve is far easier to use to setup toolpaths then the shopbot software. since you draw in autocad it would make setting up your cuts far easier. plus you get to see what it will look like and that helps quite a bit.

henrik_o
09-12-2007, 02:38 PM
James,

I think your reasoning is sound and sounds well researched.

We opted for the 120-60-14 for a few reasons that applies to us and what we do;

- We occasionally process 120-60 sheets so that size is a plus for us.

- We also opted for an additional z. This more or less mandates a 60" y travel, since a normal-sized 96x48 panel can not be processed by the main z axis over the entire width on a 96-48 table.

- We chose the 14" z for two reasons: in order to use the PRS as a point to point system for curved furniture parts which require more than 8"; and in order to machine certain parts that are already assembled (such as customizing certain parts with v-carvings and so on) right before shipment, allowing us to very rapidly ship customized work.

myxpykalix
09-12-2007, 04:52 PM
James,
A way to possibly save some money if you have a way to transport is to talk to shopbot about "prebuying" the demo units they take to the shows that they don't want to have to disassemble and ship back. If you are going to the IWF and they are taking your model you might want to talk to them, if you can get a good deal and save some money it might be worth the effort.