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Shopbot Cnc Router


bluespresence
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Does anyone here own one or have you used a shopbot CNC router or similar model?

A friend and I are looking into purchasing one and setting it up here at my house for both of us to use. He is a long time wood crafter that has run out of time for the amount of work he has backlogged (8 month waiting time on his orders). I am interested for several reasons, only one of which is guitars.

Here's a peek at one: ShopBot

We're looking at the PRTalpha96. I'm sure if we get it you'd all like to come over and use it!! :D

Any comments are appreciated!

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check out thornguitars.com. Go to the discussion forum, there was a thread a while back on the shopbot.

Ron Thorn builds his own cnc machines, so he knows what he's talking about. His opinion of the shopbot is that it is pretty much crap. Cheap parts and large tolerances. Check the thread for more in depth info. Sorry, no link.

gwm

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gwm Posted on Oct 31 2004, 09:49 AM

His guitars are amazing too.

Yeah!! I was on there for about 2 hours drooling. My brain kept saying "Buy one - Buy one" and then I'd go "but you play bass moron" and then my brain would say "who cares - buy one, buy one - they're beautiful", etc....

It was a true schyzophrenic moment........... :D

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We use one. It's a love hate relationship. We replaced the control box and steppers to get a higher resolution. Yeah it's rickety and under built, but they have a great forum with lots of support. My initial thoughts were it would be one way to get into CNC without the lease payments putting me out of business while I dealt with the learning curve. My personal learning curve took a year before I felt comfortable with the CAM software and the concepts of CNC (this would have been shorter if I would have stuck with 2.5 D and a single head) and another year before I felt I was really competent.

We've used it to build several hundred guitars as well as circuit boards, inlays (we don't do a lot of that), mountain bike parts, pickup parts, jigs, gears.

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ddg......thanks for the input. Do you have any problem with the finer work? One of the projects I would use it for would be guitar bodies and necks but I do have plans for other, more detailed work. ShopBots literature seems to indicate that fine detailed 3D sculpting is possible.. Is this "smoke and mirrors" or is it a possibility?

Thanks!

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ddg......thanks for the input. Do you have any problem with the finer work? One of the projects I would use it for would be guitar bodies and necks but I do have plans for other, more detailed work. ShopBots literature seems to indicate that fine detailed 3D sculpting is possible.. Is this "smoke and mirrors" or is it a possibility?

The first thing you need to decide is your defininition of finer work. What are your tolerances? Are you talking +/- .01 or +/-.1 of an inch? Also what kind of repeatability you need? If you were to make the same part over and over again, what kind of tolerance do you need from part to part?

There seems to be some question as to the rigidity of this machine. The machines rigidity will effect both accuracy and repeatability. Another big factor tied to machine rigidity is machining speed. The more rigid the machine, the faster and deeper you can cut.

Any time you purchase a piece of equipment like this you should ask for a demonstration. Have them cut one of your parts. My company was looking for a new wire edm machine. We found one that was 1/2 the price of the big name machines, but everyone said it's to cheap to be any good. So we went to the showroom and we brought a test piece that required the tightest tolerance we expected this machine to hold. It did it with no problem, so we bought the machine and we love it. If it wouldn't have held the tolerance we would have walked away and only been out the piece of steel. It's cheap insurance to get a demo.

I program, setup and run a cnc mill and edm machine a work so I know a little about the process, although, i have never seen a shopbot machine. My comments are more based in my knowledge of more industrial sized equipment.

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All great points jer.....We are planning on seeing a demo at the woodworking show in January before we decide. My friend has seen it and he is planning on using it for furniture building to increase his productivity. I plan on doing guitars, necks, sculptures, pickguards, pickup rings and a variety of other things that come along. Our other choice is to design and build our own which we feel is the most cost effective but it takes a lot more time. The shopbot is attractive because of the price and the plug and play (almost) feature.

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ddg......thanks for the input. Do you have any problem with the finer work? One of the projects I would use it for would be guitar bodies and necks but I do have plans for other, more detailed work. ShopBots literature seems to indicate that fine detailed 3D sculpting is possible.. Is this "smoke and mirrors" or is it a possibility?

Thanks!

We avoid 3D sculpting, it's really slow. I'm not sure you'd be blown away by the surface finish of really detailed 3D work. As jer7440 suggests, have them do a sample.

As far as finer work goes, we routinely rout with a .033" bit in wood, plastic and aluminum.

Edited by ddgman2001
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3d work does tend to be slow on any machine. To get a really good finish you have to use a cutter stepover of only .003 or .004 of an inch. (this is assuming a .500 dia. ball nose cutter).

Another huge thing to consider is how are you going to program this machine. If you use a cad/cam program, what is the learning curve like, and how much does the software cost. In most software 2d stuff is very simple to draw and to program cutter paths. The 3d stuff is where it gets more difficult.

At work I use a program called Mastercam, and most of what I do is 2d. This software also has great 3d functionality but it takes some getting used to. From what i have heard mastercam is one of the easier softwares to learn, but it is fairly expensive for a hobby operation. This PG post shows a Les Paul top i designed using Mastercam http://projectguitar.ibforums.com/index.php?showtopic=11507 I hope to start cutting this sucker around x-mas time. :D

Any way all that to say your programming system is important too.

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Thanks jer. I am quite adept at AutoCAD since I use it at work often but that is all 2d. I do screw around sometimes and design 3d stuff when I am bored so I am a bit familiar with 3d but no expert. I do own AutoCAD 2004 on my home PC already and I did see in the shopbot lit that it can import .dwg files with a transfer program you buy from them for a few bucks. I haven't had much time to research the one Scott put up but that looks like a nice alternative to the shopbot at about the same price.

Obviously we need to do more research before moving on.....

Thanks!

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