Official Luthiers Forum!

The woodworking shop at the school where I work has acquired a used Shop Bot. Apparently it's a scaled down CNC machine. The interesting possibility for me is that of designing and cutting bridges and neck blanks (!).

Does anyone know much about this machine, or better yet, have programs already written for guitar parts?

Ken
Durham, NC

I would not call it scaled down. It is a CNC Router table 24 wide x 32 long with 5" clearance is their smallest unit

seehttp://www.shopbottools.com

I had in mind a cute little robot that cleans up after you and keeps you company.

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Mike

"The Dude abides. I don't know about you but I take comfort in that. It's good knowin' he's out there. The Dude. Takin' 'er easy for all us sinners. Shoosh." The Stranger

I used to follow a forum on this subject, will see if I can find that link...

Isn't there a forum here on this subject?

Here is the one I used to follow: http://www.cnczone.com (check the DIY sections)

I've watched the company and tool evolve over the last several years at woodworking shows, etc. Most recently at the Healdsburg guitar festival. LMI has one now for various shop tasks.
Good machine with excellent customer support.
If I was 20 years younger and not so stuck in my shaper/pattern ways I'd get one.
-C

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Freeborn Guitars
and home of BeauGuard©

Could it be programmed to cut bridge blanks, and necks?

Ken

(Yeah, if it vacuumed the shop at the end of the day, that would be outstanding )

With out a doubt. I’m pretty sure necks would have be done in multiple setups with this machine so indexing would be critical, I have not looked into them enough but believe they are a single tool or single head machine which means that programming needs to account for tool changes.

Yes, it can do pretty much anything on a guitar, necks bridges rosettes even thickness backs sides tops etc.
If you can draw it it can cut it. With a right angle head of some sort you could even do fret slotting.
Luthiertool.com will be releasing their version of a cnc this year. I saw a prototype at a show last weekend and it sure is cute!
-C

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Freeborn Guitars
and home of BeauGuard©

If it can make bird houses, I'm in!

Mike

You can cut everything but the tenon, truss rod, and headstock profile with one setup and one tool. The headstock adds one fixture to the total, and you can do the rest on a router table or with a drill press. The CNC won't be able to do everything without changing tools, but you can do the brunt of the work on the machine and finish up in a few minutes on a router table.

You can find some basic fixtures to copy for holding necks and bridges on the Taylor website or Jim Olson's website. There are some serious improvements to be made on that design, but it's been working for most of the industry for quite awhile.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Thanks for all the info, guys! I'll follow up on it.

What I had forgotten, but someone reminded me of mid-day today, is that the fellow who invented the Bot (Ted Hall) is a parent of two of our students. So I sent him an email today, which he replied to, and which he forwarded to his wife, who does a lot of their set-up and programming work. She emailed me back also, and told me that while she didn't know too much about guitars in particular, she had in fact gone out to CA to help LMI set up a Bot for a couple of their tasks. Wow! Talk about a small world! So she and I have been emailing back and forth, working out a couple of meeting times. When I told her that I was interested in bridges and necks, she said that those were two things she was hoping that I DIDN'T want to try to do, because they were somewhat complicated 3- and 5-axis operations, but that it was totally within the possibility of the machine. (She must know a LITTLE bit about guitars, after all). So... I'm psyched!

I'll post updates on what I learn, and how the work goes!

Ken
Durham, NC

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Ken Mitchell
Durham, NC

OK, in all seriousness, use the following technique. Build your first one out of MDF, single axis. Then use that one to build a more accurate version. Then use the accurate version to build a 2 axis CNC machine. You get the drift... By the time you get to the 3 & 4 axis machines, you will have a kick a$$ machine at 1/3 the cost.

And, you can produce copies for pennies on the dollar!

Do my comments qualify as luthier talk?

Mike

Necks could be kind of hard for a beginner, but bridges are a piece of cake. Neither require a fifth axis, and a fourth axis would be wasted on cutting necks as you can cut them faster in three axes (barring a 4th axis setup costing more than a full-size ShopBot). I'm mentioning this stuff as encouragement, saying something needs a 5-axis machine is scary talk in machining! Lots of guys are cutting objects resembling bridges out very quickly after they aquire access to or ownership of CNC machines. Necks are a bit more of a challenge both in CAD and in CAM, for a beginner, but you'll learn a lot about CAD and machining wood by figuring out how to do necks. The CAD part is sort of hard, the CAM is easy to get the machine to cut one...it's hard to get it to cut one fast!

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I've been planning to get a Buddy unit from Shopbot as soon as I'm able. My goal is to do a few things like the
faux binding and purfling cuts on fingerboards, pinless bridges, logos and logo cavity cutting and a few others.

I've seen them run and have been able to closelt examine amny parts made on them and their quality and their
capabilities are top notch.

Regards,
Kevin Gallagher/Omega Guitars

OK, I'm set up for a tutorial today with someone from Shop Bot!

I cut and pasted most of your comments to take along - thanks!

I'll report back what I learn.

Ken

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Ken Mitchell
Durham, NC

Me too, Kevin - Shopbots are great machines and their forum is a lot like this one - I posted about the buddy on our own CNC forum here - I know of at least one other well known Luthier that has a 48X48 machine in his shop as well...

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Mitch

I was under the impression that successive generations accumulate error rather than reduce it.

How many axes does the Shop Bot have?

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

They're 3 axis machines.

And, yeah, successive generations do accumulate error. To make something like a ShopBot you need something like a high-end CNC router, to make a high-end CNC router you need something like a Haas or a Fadal, to make a Haas or a Fadal you need a really accurate surface grinder and mill, to make a really accurate surface grinder and mill you need a jig boring machine, to make a jig boring machine you need...a lot of cash.

Generally the accuracy of the tool used to build another should be 10x the accuracy of the product tool.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

We use one. It's an older PRT. No where near as well made as the current models. I feel it's a pretty powerful machine that can take you to creative places you'd never be able to get to otherwise. The learning curve is steep and long. My machine is way too light to get a nice finish cut, so we sand more than we would with a heavier machine.

Bob I'd like to see the edge finish you get off of your machine in some of the woods we use. I bet its close to as smooth as a jointed edge.

Ken,
I know this post is a few month's old but am hoping to get an update on your Shopbot experience as I have narrowed my CNC search to the Shopbot Buddy or K2 Luthier package. I have not heard much bad about either and could get the Buddy sooner than the K2. I have Rhino and Visualturn so Visualmill would be similar. I am trying figure out if Mecsoft software can be used with the Shopbot and what there software is like.
Thanks,
Mike Fleck

Mike,

After doing a couple of tutorials with the owner's wife, who is very knowledgeable about the program(s) it uses, we were able to cut some bridges, contoured, with holes, slot, the works. I could never have done it alone, but it looked like with practice, the programs are pretty user friendly.

I guess it depends on how good you are with CAD type design programs. I'm pretty unskilled But I think the machine can handle a lot of tasks, and do them well. LMI has a couple, in fact.

If you need more info, send me a PM, and we can talk further. But I may have to refer you to their customer service. Like I said, I am not skilled enough to do this type of stuff un-aided!

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Ken Mitchell
Durham, NC

Mike,

After doing a couple of tutorials with the owner's wife, who is very knowledgeable about the program(s) it uses, we were able to cut some bridges, contoured, with holes, slot, the works. I could never have done it alone, but it looked like with practice, the programs are pretty user friendly.

I guess it depends on how good you are with CAD type design programs. I'm pretty unskilled But I think the machine can handle a lot of tasks, and do them well. LMI has a couple, in fact.

If you need more info, send me a PM, and we can talk further. But I may have to refer you to their customer service. Like I said, I am not skilled enough to do this type of stuff un-aided!

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Ken Mitchell
Durham, NC

Mike,

After doing a couple of tutorials with the owner's wife, who is very knowledgeable about the program(s) it uses, we were able to cut some bridges, contoured, with holes, slot, the works. I could never have done it alone, but it looked like with practice, the programs are pretty user friendly.

I guess it depends on how good you are with CAD type design programs. I'm pretty unskilled But I think the machine can handle a lot of tasks, and do them well. LMI has a couple, in fact.

If you need more info, send me a PM, and we can talk further. But I may have to refer you to their customer service. Like I said, I am not skilled enough to do this type of stuff un-aided!

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Ken Mitchell
Durham, NC

Smoother, unless your jointed has a truly helical head (ie: giant curved blades). You should be able to get something akin to a planed edge on a rigid machine.



Visual mill puts out G-code, which is industry standard. There is also a G-code converter for ShopBot, but I can't speak for how well it works or doesn't work. The non-G-code-native controller would be a big negative to me in terms of a machine. Based on that, if the specs are the same, I'd go with the K2 machine.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

Just for grins, if someone really wanted a cnc machine for making bridges and other small parts, wouldn't that Craftsman CNC tool be the cheapest way to go? (~$1800 I think)

Mike