ShopBot Desktop router up for the challenge?
 

Our team is in a position to buy a CNC mill or CNC router in the neighborhood of $10K and I was hoping to get a feel for the pros and cons of our options from people who are actually familiar with mills and routers :). The four factors we are trying to balance are 1) Tolerance 2) Space savings 3) Cutting volume 4) Noise level.

Right now I am leaning towards the ShopBot Desktop with spindle and enclosure. It can fit on our benchtops (32" deep), the enclosure will help with sound, the cutting area is decent (24"x18"), and they are local to us. Does anyone know if the Desktop has the tolerance to cut 1/4" aluminum plate for a gearbox? I know that the Velox routers do, but their size makes them a little less attractive.

We have the ability to outsource large or complex parts to a sponsor, but would really prefer to do 80% of the work in-house if possible. We have a grant opportunity to help fund this, so buying new is more convenient, but could probably go used if it is available now.

We are also looking at different CNC Mills. The speed and tolerances they provide are really attractive, but it looks like they will all have to take floor space, and the noise may be a problem in our small shop. Also, am I right to believe that mills would make machining aluminum tubing much simpler?

• Is the ShopBox Desktop capable of cutting 1/4" aluminum close to +/- .001" similar to a Velox?
• How much easier is it to machine aluminum tubing on a CNC mill vs a CNC router?
• Would the extra speeds possible on a mill negate the noise issue (ie. cuts are loud but only take 5 minutes vs 30 minutes?)

Re: ShopBot Desktop router up for the challenge?
 

You could do a Tormach Mill with a little bit of tooling for right around the $10k mark (barely). If you were going to buy it, you should buy it right from the source rather than from Little Machine Shop. You may want to look into the 770 and perhaps even the 440. They are cheaper (and smaller) than the one you linked. Do not forget about the cost of a stand and possible enclosure. These things are worth it. I'll be standing next to a Tormach mill and their representatives this week. Let me know if there's anything you'd like me to look at or ask them.

I cannot recommend the other two mills you linked. They are oddball Chinese machines, and I doubt you would be happy with them.

As for noise, a router would likely me MUCH louder than a mill, especially in aluminum. And yes, it is substantially easier to cut aluminum on a mill than on a router, but the router can make bigger parts, whereas the mill can make thicker and more precise parts.

If there's any possible way you can swing it in the budget, it would be hard to go wrong with a Haas mill. They just introduced the Mini Mill Edu yesterday. But, you would need space for it and power and air for it.

Re: ShopBot Desktop router up for the challenge?
 

Team 303 has had a shop bot for 2 years now and we are starting to get comfortable with it. We have the larger buddy and bought the 8' power stick.


1) Tolerance: Center to center tolerance is quite good. We have made a few gearboxes in 1/4 inch plate, in addition to a lot of c-c chain runs and gear-driven mechanisms which require good tolerance. +-0.001? Probably not. Id say the tolerance for c-c is 0.003. Most of our gearboxes have come out perfect but we have had some super tight chain runs along with a few which are a little loose. But IMHO, 0.003 is enough for most any FRC application. The sb desktop page boasts a resolution of 0.00025”. I would be surprised if that was true. One thing to mention is that because of bit flex and I think the buddy's tolerances, the diameter of a pocketed hole always comes in about 0.005 undersized. To compensate we oversize a tad in cad then ream holes for bearings.


2) Box: We have machined tons of wood for prototyping, 1/8" sheet aluminum, 1/4" aluminum, 1x1 box, 2x1 box (both dimensions) and 2.5 x 3 box. The wood is amazing, with just a few screws into the wasteboard the buddy will fly through wood. The sheet aluminum is just as easy. We screw down the sheet in the corners, drill any holes and put more screws in them, then we profile it. As for box, originally we tried holding the box to the wasteboard with wood screws and washers but it was not nearly solid enough and a dangerous and bad idea. Next we tried screwing two vices down to the washboard and that was okay. It took a while to get the vices perfectly square but we eventually got the hang of it. In this offseason we built a more elaborate setup with a wasteboard and two vices off to the side just to keep the vices out of the way of the board. We are really liking this setup.


I am now just realizing the desktop doesn't come with a wasteboard, but rather an aluminum deck and that you plan to get the spindle when we have the router. I cant speak for the spindle but I highly recommend permanently attaching a vice or two to your aluminum bed along with a wasteboard as it will make sheet and box much easier. Once you spend a while getting them perfectly aligned, it becomes a breeze to machine box. I highly recommend the 3 axis zeroing plate:


https://store.shopbottools.com/colle...ant=7825832513


It makes finding the edge of box super easy, plus it tells you if your piece isnt aligned with the machine.


Just a few final notes: 18x24 is pretty small. If you plan on doing primarily gearboxes then you will be fine but we have made drive rails and longer box cuts with great success with the longer bed. Just keep the desktop max in mind. Be prepared to break a bit or two when learning. We use these bits:


http://www.amanatool.com/products/cn...uter-bits.html


Mostly with ¼ cutting diameter. We also have a 1/8th which we use to drill 10-32 holes in gearboxes. In comparing it to a mill, it will be easier to do box on a mill but it is certainly possible to do it on a shopbot. Another good tool to have is this:

https://www.amazon.com/Fowler-54-575...ds=edge+finder

It helps when trying to manually find zeros or if you need to shift a long piece of box and zero with a cut in the middle

Wow I didn't expect to write this much. If you have any questions feel free to ask here or PM me.

Re: ShopBot Desktop router up for the challenge?
 

Yes, no question any router is going to be substantially louder than these mill choices.

Re: ShopBot Desktop router up for the challenge?
 

That Charter oak mill looks interesting, although I've never seen one before (maybe somebody else could chime in?). It advertises AC servos, P3 ball screws, and and an NT30 spindle upgrade. Unless they're fudging those numbers, it should be a lot better than a Tormach. You could try getting a demo of some kind with them just to see what they offer.

Re: ShopBot Desktop router up for the challenge?
 

Go with the ShopBot. They are local (Literally up the road in Durham), know all about FIRST and FRC, and make great tools. Give them a call, tell them you want to take a bunch of students on a tour of their shop, and then see what kind of deal they'll work with you and get help from them when picking out what you need. They really are an amazing company and I'm not just saying that because they have sponsored us in the past.

Woah, an inexpensive (relatively compared to the other options they sell) Haas machine aimed at education? We'll be taking a good look at this one.

Also, if anyone else is encountering a 404 when they try to visit the Haas page, I found a data sheet for it: http://haascnc.com/DOCLIB/Datasheets/DS_MM-EDU_US.pdf

Re: ShopBot Desktop router up for the challenge?
 

Yeah, that's why I am considering it, it seems to be made with great parts and has a much larger cutting area than the other new machines in our budget. Can't find too much online about it though.

Tormach definitely looks great, but the small cutting area and floor mount are tough. IFF a smaller router can get us accurate gearbox plates in 1/4" aluminum, then that may be all we need. Let me ask this, what would make you buy a mill over a router?

What makes you say that about the Charter Oak one? What would it's downsides be?

Oh and THANKS for the info about a router being louder, good to know that I had it backwards :)

Re: ShopBot Desktop router up for the challenge?
 

The link Dave posted was missing a letter. http://haascnc.com/whatsnew-MINIMILL-EDU.asp should work.

FWIW this isn't as screaming a deal as I first thought. If you spec this out as a standard minimill is configured you basically end up at a slightly better price than the educational discount Haas offers for a purchase of any machine, with a worse warranty (educational purchases come with a 2 yr warranty, this one you have to pay for a 1 year warranty).

The kicker may be the extras they include as part of the classroom kit. It doesn't specify what those are, but if they're including CAD/CAM and tooling certificates that could well push it over the top.

That being said, if you don't need all the things that come standard on the non-educational minimill this would be a great way to get into an entry level machine that is going to be worlds better than any hobbyist grade machine (including tormach).

Re: ShopBot Desktop router up for the challenge?
 

I suggest you find a way to make room for a machine that will do what you need. Specifically, having the ability to cut your own rails. So I suggest an X or Y axis of at least 36 inches, so that you can do an entire rail without repositioning the piece.

I like our Velox, so in your position I would seriously look at the VR2536 with a 3 HP HSD spindle. http://imgur.com/a/sXwSB

At least look at the http://shopbottools.com/mProducts/desktop-max.htm but I would be leary of the 1 HP spindel.

A spindle is significantly quieter than a router on these type of machines and gives you a way of controlling your tool speed(RPMs). You will need to mount some type of coolant system compressed air and/or a mist system. You can't be recutting the same chips over and over, so compressed air to clear the chips is a must. These single flute tools from tools today do a great job on aluminum and clear chips pretty well. http://www.toolstoday.com/p-5801-sol...uter-bits.aspx

You can build your own enclosure and/or get a vacuum hood. https://www.youtube.com/watch?v=rrKKsYCb8Tg

I suggest you get something you can grow into, once you start your own machining I doubt you will want to do less.

Re: ShopBot Desktop router up for the challenge?
 

Thanks for fixing the link, slip of the mouseclick perhaps. As for Haas vs Tormach, let me put it this way: the Haas can cut aluminum at the speed the Tormach makes its rapid moves through air. Also, the Haas comes turn-key ready to use. The Tormach can be a little bit of a project to get fully up and running. Also, when the Haas breaks, they come fix it. When the Tormach breaks, you fix it. That said, I successfully bored 60 holes to within .001 on our Tormach lathe tonight, while the Haas lathe sat powered off 15 feet away. For lathes, the Tormach has kind of been our go-to machine for the past year or so but for mills, Haas is where it's at.

What makes the Haas Mini Mill EDU cheaper than the standard Mini Mill is that it does not come with a tool changer, which may or may not be a big deal for you. For me, I would go crazy having to manually change tools, but with a CAT40 spindle it's not as bad as some other systems.

And as Cory mentioned, the Haas is easily twice the machine the Tormach is, any day of the week. When we first started into CNC machining, we almost pulled the trigger on a Tormach 1100 fully optioned out, but if I recall, the price was up around $22k with tooling and whatnot. We were able to push tooling to a separate budget, up the machine budget a little bit and go for the Haas, and it's been one of the smartest things we ever did. I filled a 55 gallon drum with chips machined in it it just today. Try that on a Tormach.

As for router spindles, anything less than 2HP is not going to give you any respectable cutting power. We've had a Porter Cable 2 1/4 HP and a Hitachi MV12 2 1/4 HP. The Porter Cable was deafeningly loud. The Hitachi is substantially quieter, but is smaller in physical size, and lacks the torque that the Porter Cable had. I can imagine cutting with a 1HP spindle to be akin to watching paint dry.

Dave and Cory,

Thank you so much for posting your thoughts on the Haas machine! We were looking towards a Tormach, but this new option will probably be high up on our machinery purchase list this season. Also, I'm really intrigued about the included curriculum etc. listed on the data sheet so I put a request for more info in. I will update everyone if/when I get literature and material from Haas.

Thanks again!

Re: ShopBot Desktop router up for the challenge?
 

Just to be clear, in your opinion is "respectable cutting power" needed to make an accurate gearbox plate? Or is it just needed to make an accurate gearbox plate in a reasonable amount of time?
Our situation is such that right now we will probably only make one or two custom gearboxes in a season and are willing to spend the time. In the future we could upgrade to a big beefy spindle and improve that time.

Re: ShopBot Desktop router up for the challenge?
 

Both those wood router spindles are going to be far less powerful and capable than the 1 HP three phase spindle that comes with the shopbot. Wood routers are usually advertised with peak H/P numbers and are less efficient than a proper spindle.

Re: ShopBot Desktop router up for the challenge?
 

THIS! EVERYTHING THIS.

Please find your selves more room to put a bigger machine in, the cost is marginal and the utility is HUGE. Please don't limit yourselves to 24", I know it's a lot of room but it is such a valuable machine. We machined at least 75% of all 3 robots we built last season with our VeloxCNC 50x50, you will use all the space you buy.

You could potentially mount it to a wall and not the floor to make the foot print smaller, Velox should be able to handle it without noticing. Just be clever and I'm sure you can come up with a solution, we build robots after all.