Advice on a new ShopBot setup :-)

[sales@smart-group.co.uk]

We are considering buying a ShopBot system. We have narrowed the choice to a PRT 120- 60 machine. This would be running a single speed 220v router. We have asked for the proximity switches and the zero plate (from reading around these pages these seem pretty vital bits of kit).
We are also looking at a vacuum hold down system using a 7hp single phase motor.
We will be using the machine primarily for the sign and display market. I was wondering if anyone else has experience with this type of machine setup and has any helpful hints they could pass on.
Would the vacuum system be powerful enough? We will be using 3- 6mm acrylics and PVC foam boards- we are new to this so it's hard to assess what we need.
How have other sign shops found the ShopBot system? Has it had a big impact on your business? We want to explore new markets- a few exhibition contractors have expressed an interest in using the machine when we get it. Have you found any niches that your ShopBot has filled for other companies?
Any advice you can give will be greatly appreciated- we are based in the UK so we are keen to make sure we start off on the right foot :-)

Thanks in Advance
Andy

[gerald_d]

I certainly wouldn't buy a 7hp vacuum to start off with. I would try to get by with a "vacuum cleaner" motor and see if that isn't enough.

A 7hp motor is a monster, and normally they don't even come as single phase. The power consumption of this beast (simply to hold down thin plastic) is extremely wasteful on energy.

[elcruisr]

Sorry Gerald, can't agree with you. We cut for several sign shops and started with the above mentioned vacuum pump on our 144 x 60. We also started pushing sheets around the table as we learned just how fast we could push the feed speeds. If you don't mind being limited in what you can do and production time means nothing it will do. If production time equals $$$ to you, get a 15hp blower minimum. I have one and can still wish for bigger on the occasional job. Yes my table is well made and sealed to prevent unwanted leaks and it has six controllable zones. The foam will be easy, the cutting forces are miniscule. 6mm acrylic isn't too bad untill you start trying to cut smaller parts and letters that have been nested to reduce waste. Then you'll need plenty of vacuum to hold them from sliding around. Also consider all the other stuff you can cut with it and you may find you horizons expanding, we certainly did!

Eric

[gerald_d]

Eric, my impression is that Andy is not yet quite sure what he wants to do with the ShopBot. He wants to explore some possibilities and I don't think that he should spend too much on the tooling yet. And being in the UK, he is probably going to find a better supported vac pump over there, set up for 50Hz mains frequency. Plus he will have less shipping charges.

[elcruisr]

I agree that he should buy a pump in the UK but an undersized vacuum system on a machine used proffesionally is a major headache. It slows you down and can cost you trashed materials. We found ours slightly used and saved a bundle. Check out the surplus and used machinery dealers in your area.

Andy, are you considering contract cutting for other businesses or just in house work. Think about ALL of the materials you might cut when sizing your components. It will help you make better choices now....

Also give consideration to the software you'll be using, you'll be spending a good deal of time with it. Will it do everything you want it to?

If at all possible get a multi-speed router or a heavy duty speed controller. Most routers turn way too many RPMs for the feed speeds a shopbot generates. Yes you can still make the cuts but it will shorten tool life and can cause melting problems in acryllic. CNC tooling is a whole new education from router bits!

[Andy (Unregistered Guest)]

Eric, Gerald- thank you both :-)

You are both right in what you are saying. I'm not really sure what we will be doing with the machine.
I have been researching the market here- the biggest machine that I know of in a 50 mile radius is an 8 x4 machine- which is still a bit small for sign work. I think the reason for lack of big machines is price- big routers are very expensive over here.

This is where the ShopBot comes in- for the price quoted by Jamie I can get a full system for a realistic price.

I am planning to approach shopfitters, builders, engineering firms and anyone else I can think of.

The materials I envisage cutting are sign foams, acrylics, plywood, MDF, and aluminium. The hold down system needs to be man enough to cope with this.

A vac pump sourced from this country is probably going to be double your US price- at least. Are there any US manufacturers who export this stuff? Would the ideal HP be 15 or should I look for 20+?

Eric- on the bit about routers- can the shopbot take pretty any make? I was thinking of sourcing the router over here- I have a heavy duty- multi speed Bosch machine already. I just don't know how the router fits into the ShopBot assembly. What would you recommend in terms of max RPM and wattage for the router?

Software- this is another unknown at the moment. We use Corel for our vinyl cutters and inkjet printers. I have been using Corel since V4 so I kinda know the beast inside out. I have downloaded the ShopBot software to play with- it seems pretty easy but it's hard to tell without having the bot ready to experiment. What would you recommend? I was looking at TurboCad as an option.

Thanks for your help so far.

Kind Regards
Andy

[elcruisr]

Andy,
Let me tell you what happened with us. We bought the machine to cut pre laminated plywood parts for our business. We also hoped to cut for other companies in our area. It did that and helped speed up our production. We bought a 60 x 144 because I occasionally needed that length. Over a year we have watched cutting for outside shops jump to close to 65% of our business. We even handle jobs for other companies with CNC capabilities because of the size of our table. Luckily we started out with a well equipped machine.

I don't know your budget but if you can get a full blown CNC spindle, you should be able to source one there. They will outlast and out cut any router out there. They also offer RPM control of .1 RPM throughout their range. I cut and drill as low as 7,000 rpm on some jobs. I typically cut in the 9,000 to 14,000 range on wood products and plastics. A shopbot's feed rate just dosn't call for more RPMs with true CNC tooling. If you go with a router you will just be mounting the head. You can pretty much mount any round bodied router head. A quick call to Shopbot will tell you if they've mounted a particular brand themselves. Plan on rebuilding the bearings fairly often if you do alot of production. That's another nice thing about the spindle, 2,000 to 4,000 hours bearing life. Make sure you keep extra collets around, their usefull lifespan for CNC work is usually around 200 hours. We use mostly 3/8" tooling with some others running from 3/32" to 1/2". Beware cheap tooling if you want the best results!

Another option we are glad we have is the double y-motor option. I find that for production routing it helps us tweek that last little bit of speed and accuracy out of the machine. Also remember dust control, a large shop vacuum or dust collector will keep the dust down to a reasonable level.

There should be plenty of companies willing to ship vacuum blowers your way. The trick is to find one that uses your electrical standard compared to the USA standard. An easy dodge might be to find one, have the electric motor removed and install a local motor. An internet search of places like Ex-factory, Woodquip, M-MLS, etc might turn up a good pump. Our 15 hp is what I now consider the smallest adequite pump. I'd love a 20 but that's not in the budget right now.

You can easily draw in Corel, we import customers files from them all the time. There's tricks to how you save the files but nothing hard to do. What you want to think about is the toolpathing software. I'd start with the Shopbot Parts Wizard but realise that if it really takes off for you, you'll want more powerful controll of your toolpaths. Delcam in your neck of the woods makes two levels of Artcam software. We use Insignia from that and I am only moderatly happy with them. We do push the limits of the Shopbot and the software but I have found several major glitches for Delcam and am still waiting for them to fix a very major one for months now. If I had to do it again I'd probably go Mastercam and might still if Delcam can't get their act together. These programs are very expensive but if you get busy enough can pay off fast. You can design, draw, create toolpaths, nest, manipulate finish passes, onion skin, create and manipulate tabbing, etc, all in one program. Still, learn the ropes with the Parts Wizard first, much easier learning curve.

Whew! Long post!!!! Do your reearch and ask lots of questions, you're on the right track.....

Eric

[gerald_d]

Andy, you are trying to grow three things:
- Your market
- Yourself, in terms of knowledge and CNC experience
- Your equipment or tooling.

My suggestion is to balance out those three things. All three of them can grow with time. You won't lose anything if you mount your Bosch router now and go bigger later. Same as starting with Corel and PartsWizard now and thinking of something better later.

Unless you have just won the lottery of course . . . .

[Andy (Unregistered Guest)]

Thankyou again guys.

Eric- could you explain the double Y motor a little more- do you think it's something I need to go for straight away?

Gerald- I think you are right. I'm probably going to start out simple- using the Bosch and the software I already have. Then, when I have got to a reasonable level I will look into upgrading the software and spindle as Eric suggests.

I am planning to build up the work slowly- I can't see myself doing outside work for a least a couple of months until I have a handle on what's involved.

The main thing that I have working in my favour is the exchange rate- £1 buys me $1.9 worth of equipment from the US. This makes my limited budget stretch a lot further.

When I have worked out a new spec I will post here again- if you could take a quick look and let me know what you think I would appreciate it.

Thanks again you guys- I appreciate it

Andy :-)

[elcruisr]

The extra y motor can be added at any point. We added ours after about 1 1/2 months. It just adds more and better balanced cutting force on that axis. It meant another .5" of speed cutting 3/4" plywood for us. Some would say that isn't much but when you're running tens of thousands of parts it means a lot!

Give yourself a few months to really begin to get a handle on running you machine. It's going to be a new set of skills to learn. Don't worry, all of us have crashed into tables, broken bits and beaten our heads on the wall a bit. The good news is that after the initial learning curve it becomes much better!

Eric

[designer@motorhome-world.com]

Hi people.Can anyone give me some advice on cutting out 16mm MDF frames.My problem is that the corners are always a bit bigger in radius to what i have designed.I am using a PRTalpha 120x60 with a Makita router.

[gerald_d]

At last I get a chance to see another ShopBot, right here in Cape Town! Gakiem, daar in Atlantis, as ek nie eerste vir jou bel nie, bel my gerus by 448 8872 (Woodstock).

[gerald_d]

Have had a chat with Gakiem and he is visiting us tomorrow for a "mini-camp" - knowing full well that his alpha rocket is far faster than our old steam machine.

Anyway, therein seems to lie his problem - his router seems to enter inside corners too fast, and "overshoots" the curve before changing direction. I would guess that he has to do some fine-tuning as per this thread (http://www.talkshopbot.com/forum/messages/29/4431.html). But, I havn't kept a close eye on the Alpha issues, and I would appreciate you guys trying to help Gakiem. Are there any other threads that we can point him to?

By the way, has the metric version of the software been de-bugged yet - he was forced to go back to the factory inch setting.

[paco]

How much bigger from what you expect/programed?

[paco]

Lucky you Gerald; you'll be meeting new "Botters friendship" soon!
Alpha not much different in cutting results, I believe, than a PRT since it ramp in corners and small curves normaly VERY smoothly... unless ramping settings been changed from defaults...?

[gerald_d]

He is using a 0.5" cutter at the low speed of 0.6"/sec, cutting full depth through 5/8" MDF and trying to make a simple 90 degree inside corner, with the fillet being the radius of the cutter. But he gets about 1mm overshoot, making a hollow into the corner.

At this low speed, I am starting to suspect that there is something mechanically loose, and that he is actually getting deflection as the cutter bites.

[paco]

Hummm... quite safe approach; I would too suspect something loose OR could the cutter be bigger than supposed thus doing the corner with a fillet smaller than the cutter radius resulting in a "hollow reached" corner...? (Again, please excuse my english if something seem "awckward" about this last part...) Is it ALL the corners that gets like this? Or some... Loosness should appear in straight line too, I believe...?! I would do some more checks on the designing/programing...

[mikejohn]

Gerald
I worked out how you knew Gakiem was in Atlantis, but how did you know he spoke Afrikans?
....Mike

[gerald_d]

I doubt that he speaks Afrikaans as a first or home language, but I was sure that he would understand my personalised invitation.

[gerald_d]

Paco, for example, his input file is only 4 moves, the four sides of a square:
go left (-x)
go down (-y)
go right (+x)
go up (+y)
The tool must make 90 degree changes in direction at quite a low speed. The "overshoot" happens in each of the four corners.


6236

cutter = blue
toolpath = red
result = yellow

I cannot see that this can be programming - too simple.
Ramping is factory default - but the speed is slow

I have suggested that he try climb versus conventional cut to see if there is a difference.

[designer@motorhome-world.com]

I have changed the bit to a 6mm down cutter and ran a couple of tests. Result : perfect!The climb works much better as Mr. Dorring mentioned. I dont know if anybody else on this forum has met him, but let me tell you guys something...he is such a person,it was an honour meeting him!

[gerald_d]

Hey, you make me blush. Hope to see a lot more of you!

[paco]

Glad your problem is fixed Gakiem!
I agree Gerald. Though I just don't understand what it was since I cannot duplicate on my tool...!?! Alpha is quite rigid and at slow set speed, the tool bit should'nt bite that much as producing this kind of problem in MDF... Watch for loosness at assembly. I believe you should be able to choose from both climb and conventional, in MDF, without a big difference... Do you have the latest control software installed? And update the firmware too?
Anyway, still, if your probem is fixed then everybody is happy!

[gerald_d]

I don't think his problem is permanently cured either. But he has got a few more things to think about and look at if he encounters the problem again.

[fleinbach]

This problem in my opinion is due to taking a full depth cut in a single pass. I described this issue a few months ago in another post. Large bites of material result in powerful cutting forces. These forces pull into the cut. This happens at any move speed. Lowering move speed has little effect on arresting this action.

Gerald, using your drawing above it appears the cut path is in a counterclockwise direction. The bit is also moving in a counterclockwise direction. According to Artcam Insignia an inside cut in this direction is a climb cut. Starting in the upper right hand corner you move to the upper left corner (-X) When the bit starts moving from right to left it is immediately pulled off it's intended path slightly toward the middle of the intended cutout. This is repeated at each corner and not only will it leave this indent but if you measure you will find that the intended hole you are cutting is actually smaller then you wanted. Now if you cut in the opposite direction you should not get the indent but your hole will be larger then intended.

Another way to stop this from happening is make several passes with smaller depth of cut. Or as Eric Lamoray mentioned above adding a second Z motor will help counter the heavy forces on the tool when taking large bites of material.
.

[elcruisr]

I don't think this is such a tough cut. We do single passes through 1" mdf at much higher speeds than that, 7 to 8"/sec but with a spindle. Have done both climb and conventional cut. It seems like time to check out all the bearings and the router mount.

The only times I've had issues like this I've found a loose bearing somewhere.

Also is the tool really sharp? Dull tooling can cause all sorts of problems because the cutting forces go through the roof.

Eric

[gerald_d]

Frank, I just picked the climb-cut direction to illustrate the point, and suggested to him that he try different directions to see if there is an improvement.

[fleinbach]

I just realized I ment to say 2 Y motors not "Z"

Gerald,
I figured thart I was just clarifing

Eric
From reading your earlier post are you using the Shopbot with 2 Y motors?
That will deffinatly reduce the potential for the bit forces affecting the cut.

[elcruisr]

Frank,
we were running two y motors on our PRT. Since we upgraded to an Alpha with the new carriage we have a single y motor. There's more than enough cutting force and the new carriage is much stiffer. The old PRT really needed the dual Y motor and it was essential to the production work we do.

We cut 3/4 ply at 9" to 10"/sec in a single pass. Same for MDF and particle board up to 1". Solid woods run all over the scale depending on species and type of cut. We try to stay with 3/8 or 1/2 tooling whenever possible.

Eric

[kumar_n@promocamp.net]

02.01.2006

Hi Eric,
Wish you a happy new year.

Yes, I am kumar N from Bangalore, India.
Eric, before getting in detail,I would like to tell about myself in below given few lines.

Basically, we are into sign-making and wood working industry. All this days we are working in the conventional way. But, after seeing 'Shopbot',
we decided, we really wan't to automize our way of working.

And, the request with you is, please advice us how to go about buying a 'Shopbot' for a starter with spending for the essential things to start with.(please note we would like to upgrade this in latter stages).

Thanks,

Kumar N

Promocamp Services India Pvt. Ltd.,
Bangalore, India.

e-mail : kumar_n@promocamp.net (mailto:kumar_n@promocamp.net)

[mikejohn]

Kumar
If you haven't yet done so, go to www.shopbottools.com (http://www.shopbottools.com) where you will find most of the information you need.
If, after your visit you have specific questions, post them here.
................Mike