Controlling Vacuum and Unattended Work

[Tomlin]

Hi guys

Getting closer and closer to buying a Desktop for our panel making business. I have two questions, which both have most likely been answered somewhere before but I didnt see this here in the Desktop forum so I will ask and hopefully some good answers will spring up.

First, a tiny bit of back ground on myself. I've been using a Probotix V90 for 2.5 years for my upstart panel making company (internally lit instrument panels for aircraft simulators, all made of acrylic). This machine has paid for itself many times over, but leaves quite a bit to be desired. For the price and the work that I've gotten out of it, it was a good investment! That said, I wish that I would have known how well the business was going to do because if I did I would have bought a desktop from the very beginning!

Now on to my questions.

1) Is there any harm in allowing this machine to run for a few hours unattended? What I envision is going into the shop early in the morning and having it run a routine while I leave and go to work (I am a bi-vocational business owner. 40 Hour week at my job and then several hours a week in the shop for the upstart business). Ideally the machine would run a full sheet of my parts and then shut itself off once finished and then when I come home for lunch I would run the next tool path and/or start a new sheet of parts depending on what needed to be done. So, a) is this safe since the machine will turn off the router and b) how long is too long to leave a machine? Four hours okay?

2) I would like to have the vacuum system controlled by a relay just as the router is so that it will shut off automatically when finished working. Has anyone found a way to do this with the Desktop? If so, what's involved?

Thanks for the answers and opinions. I know that without a doubt this Desktop will run circles around my V90 in all regimes (speed, accuracy, dependability, reliability, etc.) but having the ability for it to make parts while I'm out of the shop would boost my productivity to 10 times or greater per week potentially.

Looking forward to your replies!

[steve_g]

Eric…
You’re going to get answers all over the place on this…
First, with out exception, reports of fires have involved down cut bits plunging, as in drilling operations, and with vacuum hold down fanning the embers into the plenum.

Your risk of fire with Acrylics is nil. First , you’d never use a down cut bit with plastics and if you did it would just melt.

I run parts unattended when I have run the same file several times and am very comfortable with it. When working in the office I watch my Bot with a camera, viewing it on one of my multiple PC monitors. When away from home (at a restaurant usually) I can check on progress online if I’m curious because the camera is a IP security one.

Folks routinely control other things from the bot software… ShopBot has a relay board or many have used this one http://www.winfordeng.com/products/cat_rly.php (http://www.winfordeng.com/products/cat_rly.php)

SG

[Tomlin]

Thanks Steve

You are correct, I only use upcut bits. I am most interested in the vacuum being used simply to remove the chips (no hold down). I too only leave my current machine running when I'm very comfortable with the files and have pulled parts off of it that were good and of course, had no issues with the actual machine pathing.

Your idea of the IP security camera is a good one. That would give me the ability to check in on it, although I'd be 5 miles and 10 minutes drive away.

My question on the relay: Do I integrate this into the controller box on the Desktop or I guess it would sit somewhere else and wouldnt really matter. The main thing being that the Shopbot software will run other items.

[dlcw]

Eric,

In addition to what Steve said, Shopbots have a tendency to freeze at the most inopportune moments. Mine has frozen several times while simply zeroing the Z to the plate using C2 command. :mad:

There are times when it will run for weeks without a problem. Then, out of the blue, it just decides to brain-fart in the middle of a 2 hour carving job, or half through cutting a sheet of plywood for cabinet parts. With ShopBot Link, you can't restart the job in the middle, you have to start from the beginning. This has ruined many sheets of expensive plywood.

I don't trust my Shopbot (even after 4 years of almost daily use) to leave it unattended. I worry that while it is cutting something, it will have one of its brain-fart moments and freeze while the bit is in the wood spinning away potentially starting a fire. :eek:

[Tomlin]

Eric

I don't trust my Shopbot (even after 4 years of almost daily use) to leave it unattended.

Wow, that's a bit daunting. I guess the good thing is that sheets of acrylic over-all isnt all that costly.

[jerry_stanek]

I trust my Shopbot as much as I trust the Biesse that I run at work but would never leave it for more than a few minutes I do have a camera hooked up to watch and hear it run while I am in the house. No cnc should be left running for extended time.

[dlcw]

Wow, that's a bit daunting. I guess the good thing is that sheets of acrylic over-all isnt all that costly.

It might be just my machine, don't know. I know others have reported similar types of brain-fart issues. Some have told me it is humidity changes causing static, etc. Don't know as my machine is extremely well grounded (served 23 years as an electronic technician in the Coast Guard at sea where I learned grounding like nobody's business).

I can't pin it down because it is so infrequent and random in nature. The issue may have been resolved in the current generation of machines. Don't know...

[Tomlin]

I'm glad you guys are being so honest and upfront. I have ran my Probotix V90 for probably 30-45 minutes before while inside washing dishes, etc. and have never had a problem other than it losing a step and ruining a part. And, I do not even have limit switches or a relay to cut off the router on that machine (although I'm about to install one this weekend).

Is it out of an abundance of safety that you guys do not trust leaving it, or because you simply have a hard time walking away fearing you're not there to catch a freeze, etc.?

[Tomlin]

While we're on the topic of safety, I understand that the Desktop has only 2 proximity switches down at 0,0. Does this create a problem for when working near 18,24?

What I really hope to accomplish is to be able to use a near-full 18x24 sheet of acrylic and work near to the machine extremes. I called and spoke to someone at Shopbot 2 weeks ago and per my conversation with them, they assured me that because of the machine having fully supported rails that there would be no problem working at extremes and having racking issues. What are yall's experience with this? Does this seem to hold true?

[steve_g]

Yes, I have experienced the unexplained freeze ups Don referred to… usually during very dry weather. I had a rash of them recently and traced the issue back to the mowing crew demolishing the ground rod clamp! At any rate the “scorch” mark left under the V-bit was the same whether it was 10 seconds or 1 hour. I recently broke a bit (a rare thing now days) and ran for hours without a bit… I was in the next room.

If I were using vacuum hold down and down spiral bits I likely would be less trusting and stick closer. I haven’t changed to the new control software yet but I will now that most issues seem to be ironed out. I’m hoping this will help me go from 99.9% dependability to 100%. Then again most issues I have can be tracked back to the operator… Me!

Bottom line… I can’t make money “watching” the Bot. I need to be working also, either in the shop, office or elsewhere!

SG

[garyr6]

My experience with my desktop has been "i was never fast enough to save the wood or bit when the BOT decided to do me wrong" ( ok maybe it was operator error of some kind). So it comes down to is, " Are you willing to trade the possibility of some kind of damage for productivity gains". This trade is something we all do at some time, whether its CNC or anything else which involves risk (ie insurance).
Most of us picked BOTS cause of reliability..... don't mean they will never do you wrong.
My issue with BOT farts had to do with power surge when the air unit kicked on and off in the house (the two power circuits sat next to each other in the Main Power box). Moved them and almost all of my issues stopped.

[bearcat]

The DeskTop is solidly 24" x 18" and a bit more. I see consistent cut quality across the entire work envelope with plywood, acrylic and HDPE.

Personally I do not run a ShopBot unattended, and when working with clients I strongly recommend the operator stay at the machine. I am not concerned about machine stability so much as unexpected / unplanned events possibly causing catastrophic failure.

Ed

[ron_moorehead]

Insurance, I talked with my agent last week and asked about if a fire starts while I am not around the machine would I be covered, his reply basically was if the industry has a standard, like not to leave a CNC machine running unattended, then no I would not be covered. My fault. I think the ShopBot manual says not to run your machine unattended.

Talk with your agent.

[bobmoore]

In my opinion running any mechanical device remotely is a recipe for trouble. Accidents come from unexpected places (hense the name). A power outage or spike. A piece of material leaning against a wall, a car crashing through. Talk to someojne who has manged plants or safety managers and it is sobering what strange things can go wrong.
Bob