Need a little help

[44henry]

Hello, I am an instructor at the University of North Dakota in the department of technology. My department has asked me to look into the purchase of a Shopbot system for use with our technology students. There are several different options available with various accessories, what would you recommend? I'm hoping to keep my cost under 10,000, but what would you recommend within that price range? Any information would be helpful, especially actual classroom observations.

Regards,

Alex Johnson

[mikejohn]

Alex
For tuition I would recommend a PRT with a good router.
You are not going to be running a full time production facility.
Many of us do run a full time production facility with this set up, but not mass production.
You will save a lot of cash. Spend it on good design software, in particular the latest Vcarve Wizard.
With that software your students can turn out great stuff almost instantly, even possible making things that you could sell for school funds.
Your greatest asset may be this forum.
........Mike

[john_david]

Alex,
I agree with Mike with one exception. I would get the alpha because of its abillity to not loose step and position when running a file and speed of cuts. The cost is well worth it. The design software IS a very important thingand V CARVE is very good but you can do alot with Part wizard and a good CAD software also

I would be willing to help if you need it I am just west of Minneapolis call with questions
612-237-4062

JD

[44henry]

Thankyou for the response, I have been looking at the PRTstandard 96 ShopBot system with the 3 1/4 H.P. Porter Cable router. They show the system package at $9,050 plus shipping, I just don't know what more I would need to get. My department updates their AutoCAD program every two years and we are currently using MasterCAM software so I doubt there would be too many problems software wise. However, our graphics department would also like to get involved with this new system and they are using Adobe Illustrator which I've heard can work with this machine. If there was a software package that made it easier to create architectural carvings (such as ArtCAM) but at a more affordable price I would be very interested in that also.

The only thing stopping me right now from ordering is that I am having a hard time making up my mind between the above mentioned system and the benchtop model. I'm not really sure that I will need the extra capacity and there is a significant savings in going with the smaller setup.

Regards,

Alex Johnson

[44henry]

John, thanks for your input, don't be surprised if I give you a call later on.

Regards,

Alex Johnson

[44henry]

One other thing that just popped in my head, how hard are these machines to run with basic G-code? The only reason I'm wondering is that it would be nice to give students an exercise in basic G-coding and I don't know how hard it would be with these machines.

[paul_z]

Alex,

I'd also recommend V Carve. Easy to learn, a lot of capability/$, and an easy way to make stuff to sell. The students will feel real accomplishment on their first project. The Vectric forum provides help from all around the world.

Also, don't underestimate the capability of the software that comes with the Shopbot. It provides a rather robust capability right out of the box.

G code is G code, except for all of the exceptions of course! In my limited experience, it's a lot like assembly language -- it's there if you need it, but few people would use it as the basis for a project. Still it wouldn't hurt to get some experience.

This forum can be a goldmine for both you and your students. Don't hesitate to use it.

Let me know if I can help.

Paul Z

[richards]

Alex,
Shopbot software is not G-code. It is very similar in function and feel, but it is not G-code. The PRT can be equipped with an after-market controller that only runs G-code, but that is not an option (to my knowledge) from Shopbot.

V-Carve is an excellent program that does wonderful things when combined with Adobe Illustrator. It does much more than I am able to use.

I also have an Alpha, but I've spent some significant time trying to tame it. Most Alpha users are more than pleased with the machine, as am I; however, it is my understanding that the PRT, although much slower, produces a finer, smoother cut. I've recently modified my Alpha to get a smoother cut. Unless you need the fastest possible feed speed, I would recommend looking at the PRT. As John wrote, the Alpha has Oriental Motor Alpha stepper motors that have built-in feed-back; however, the motors are not synchronized with each other, so that if the feed-back feature causes one motor to slow momentarily, the other motors are not affected - which means that you'll most likely have a small bobble in the cut. That is a minor issue that only becomes a factor if you push the machine too hard. In normal operation, at reasonable speeds, the Alpha works great.

If at all possible, I would go with a large machine. You can always cut small parts on a large machine, but the opposite is impossible. I rarely need the full size of my 60 X 120 table, but I always need a 49 X 97 table. Going smaller would require the use of saws to cut up the material into usable chunks - and I would be limited in a lot of the work that I do.

Be sure to set aside funds for tooling. The proper cutters used the proper way give excellent cuts. When I'm busy, I can count on wearing out a $60 to $80 cutter at least once a day. Of course, that also means that I've cut a lot of material, but it is an expense that has to be in the budget.

[paul_z]

Alex,

Mike is correct that Shopbot can not run G Code directly; however, there is a built in software converter to convert G Code to shopbot "speak". The major commands are supported (rapid move, cut move, arc left and right, absolute mode, relative mode, and a few more). This should be more than enough functionality to convince someone to seek a higher level interface.

I have a PRT Alpha and it is fast enough for me. Actually, 30 in/sec jogs still "get my attention" and can be highly destructive. On the other hand, my machine serves a single person; Your machine will have to serve an entire class, the graphics group, and you might even want to get some time for yourself ... so maybe speed has a place in your decision matrix. Because most of the cut time is actually spent cutting, the difference between the PRT cut time and Alpha cut time on an intricate design may be very little. On straight lines, the difference can be large.

Something else you might want to check out is whether or not there is a shopbotter close enough to provide some sort of "backup" if your machine goes down. I wouldn't allow students to use my machine directly (mostly insurance issues), but I would be willing to execute their cut files if necessary.

Paul Z

[dhunt]

Do you need full-size 48 x 96 table size?
or will 48 x 48 do?
(that'll cut costs a bit)

PRT is adequate: so it may lose steps that Alpha (at greater expense!) would not:
- losing steps might teach them a few things.

What else will you need?
* Clamps! at least 6 of them, with low profile heads.
* Hearing Protection for everyone in the room!
- that Porter Cable 3.25 is a SCREAMER at 21,000 rpm!
* a caliper dial-gauge to measure thickness of material to be cut, to the nearest thousandth of an inch

[bleeth]

Alex: Delcam, the makers of Artcam, have been known to contribute to educational programs. It would be worth your while to investigate this with them.

Dave

[44henry]

Thankyou for all your responses, I'll need to look at the different size models again, a 4'x4' might just be the ticket. I'm also very interested the possibility of using g-code with this machine (though I have two Emco machining centers that I can use also). It's good to know that there is this kind of support available, I'll be using this machine for instruction in the Spring 2007 semester and probably won't manage to get it in and installed until late October, I'm definitely going to be busy this semester. Thanks again, I'm sure I'll have many more questions in time.

Regards,

Alex Johnson

[44henry]

I seem to have lots of questions tonight. I was looking at the 3D Digitizing Probe option that is offered for the Shopbot system and I am wondering if anyone has any experience with this accessory?

Regards,

Alex Johnson

[ryan_slaback]

Alex, I myself have just gotten a system installed in my high school. If you are ever in Wisconsin let me know and I can show it to you. I would highly suggest getting the full 96 inch version though. For the little bit of savings, to me it wasn't worth it. You will be surprised at all the projects which come out of the woodwork (pun intended) for you to do. I have not taught a day with the kids yet this year and I already have about a weeks worth of "hey could you do . . ." projects.

I myself got the alpha. With the rate at which technology is changing I find no reason to take a step back. My brand new machine will be outdated soon enough. Plus there are some other things which are problems with the PRT that are not an issue with the alpha --like manually moving the cars. This can cause controllers to go poof with a PRT but Chris at Shopbot has assured me this will not be an issue with my alpha as that has been corrected. That is important to me because as you and I both know the first thing that students want to do with a new machine like that is play with it and that will probably include manually puching the carriages.

If you want to get ahold of me feel free to email me at slarya@albany.k12.wi.us (mailto:slarya@albany.k12.wi.us)

[patricktoomey]

Alex, I have a digitizer probe and it works very well. It can be finicky at times but I believe the newer model has optical internals instead of electric contacts which should make it more trouble free. I have used it quite a bit. Don't expect to digitize a large surface at high resolutions unless you can run it for days on end. Luckily you can usually get away with digitizing smaller parts of repeating patterns or use lower resolution for rough shapes. I've been happy with mine and have pulled off some seemingly impossible reproductions using it.

[john_david]

Alex,
I have the digitizer probe alsofor my prt96 and it works OK and I have the new one for the ALPHA and I love it ,I dont use it much but its great when I do.
As far as the 96 vs bench top????? I think bigger is allways better.
The other not so obvious things you might need is the dust skirt and the stop sensors, and a half quarter and eigth inch collets foor the router.

[mikejohn]

John
If money is going to be an over riding problem, don't ignore the 'knitting needle', aluminium foil approach. You can be set up for a couple of dollars.
For other posters, look at John's first message, where he say he wants to get set up for under $10000. If this includes everything, he is going to have to be very selective

............Mike

[44henry]

The 10,000 was a wish, but I do have ways of getting additional funding if I need to. It's kind of looking like the ALPHA might be desirable. I had 43 students in my manufacturing class last spring and since I won't be getting more than one Shopbot, maybe speed is a factor I need to take into account.

Regards,

Alex Johnson

[djmcnutt]

I would not go any smaller then the 96" alpha, I would suggest if you have a welding shop at the school to make your own table. ShopBot has very good plans and you can save allot of monry by doing this yourself. I had mine built loaclly and saved over $1250. plus I had some changes made to allow for large pieces of wood on one side.

[jeff_rowley]

Alex, I don't have much new info to offer, but wanted to say Hi! I went to UND in the early 90's. If I still lived there, it would be fun to help get this set up.

Go Sioux! ;)

[44henry]

Hello Jeff, what department were you in? It's good to hear from UND alum.

Regards,

Alex

[paul_z]

Alex,

I made these clamps after I ran into a metal clamp (with my most expensive bit of course). They screw into my MDF spoil board and provide so much holding power that they can dent many materials. I use a pad if the material is soft.

The screws leave little dimples at the surface of the mdf but these are easily flattened out with a couple of light strokes with a small hand plane. The plane blade glides on the flat part of the spoil board but it cuts off the screw dimples.

These clamps move the screws back from the material to provide an addition margin of safety. (It's been over a year since I ran into that clamp, so it's just a matter of time before I cut though one of these.) The clamps are also very low profile to let the dust skirt ride over them.

Did I mention CHEAP !!!

Paul Z


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