CNC routing

[gfxsigns]

Hello All,

Our company recently purchased a cnc machine and only a few of our employees have had training on the machine as our shop is quite busy...I have trusted the majority of the training with one of my production guys, who does about 95% of the operation of the table now..we haven't purchased a vacuum table and to date have been taking spray glue and mounting whatever adhesive we are cutting to 4mm coroplast and then adding no bridges on the file to speed up the process...while this seems to be much faster than having bridges and having a guy sand these bridges down-part of my questions whether this is what everyone does?? Having bridges seems to take a good hour or so to sand down-and by the time you allocate the wage in there-you might as well cut your loses on a $10 peice of coroplast...your thougts?

 

[GB2]

What's a bridge? How many sheets of Coro are you cutting at one time, are they stacked? I'm sorry but I'm not really understanding your question.

 

[astro8]

What type of router is it?
You really need the vacuum hold down....really.

 

[JK driver]

You still have to seperate the coroplast from the parts you cut and clean the glue residue off. Doesn't that really cancel out the time you spend sanding bridges?
And as far as the vacuum table, get one as soon as you can. Your operator will love you for it! And over time your check book will to!!!

 

[gfxsigns]

Hi Everyone..sorry by bridge I mean 'tabs'..ie little legs that attached the letters to the rest of the sheet-we are using this when cutting substrates like aluminum, sintra, wood, plexi, alu panel etc...

we don't have to clean the back of the letters are they are usually drilled and tapped or have double sided tape applied for installation...

the router is a axyz..and the vaccum system is 10k-we had to take over another building for our expansion so the extra 10k isn't going to happen soon since our next purchase is going to be a bucket truck

 

[OADesign]

In my mind, Labor is the most expensive commodity in our business. So that vacuum would eliminate much of the prep and finishing. Plus the cost of glue and coro and sand paper/abrasive. It may seem like a minimal cost but add up your cost of glue and coro and additional labor per month over a year. Then post back what you coulda shoulda woulda done with that money...

 

[dman0427]

When you get to cutting smaller letters, the vacuum hold down isn't going to hold it tight enough. When you're cutting larger pieces, you can just clamp it down.

I've mounted the material to coro as well using carpet tape. It worked sometimes, sometimes it didn't. Then there were issues with separating the letters from the coro.

If the vacuum table could hold down every little piece without someone having to hold or clamp anything it would be worth the investment IMO.

 

[fatdogvw]

I use to run a cnc router and my trick was to cut a template first, then use double sided tape to hold down the letters. no bridge. hope this helps.

 

[iSign]

get the vacuum... finish your last purchase instead of rushing to the next one.

But for small stuff, I second the use of carpet tape

I use to run a cnc router and my trick was to cut a template first, then use double sided tape to hold down the letters. no bridge. hope this helps.

template? you mean a shallow outline on the spoil board, to show you where you need the tape? If so, I do that too... another good idea for the small stuff!

 

[GB2]

OK, so you are cutting small pieces out of Coro and leaving little tabs or "bridges" to hold it to the waste material so they don't fly out, then you are finish cutting them out and sanding down the tabs....is that correct? That is procedure I never use so I'm not familiar with it. I have a vacuum but I do not use it, for reasons that are irrelavant. I regularly use a double sided tape for holding pieces and it works great. I would not recommend generic carpet tape though, that is horrible to use. I use Intertape #591, it's the best product I've found for that purpose, holds great, easy to apply and easy to remove with no residue. To answer your question, I suppose you would have to weigh the cost of tape vs the cost of labor to sand, I imagine it would be about equal so it would come down to your personal preferance.

I've tried all types of clamps, wedges, spray adhesives, etc. and nothing comes close to the performance and convenience of using a quality double sided tape. If you don't have a vacuum then it's simply a minor cost of doing business.

 

[astro8]

Another thing...you should be able to cut down to the mask on acrylic and that will hold the letters...for other stuff you can lam app tape (Hi-TacK) over the back..maybe 2 layers.

Thats how we do small letters...1/16" bit and letters down to 1/2" high....sometimes smaller.

 

[John L]

Another option you have (without taking the jump yet with a vac blower, etc) is to get slick with your toolpath strategies.

Make sure you have a flat table. Surface it.

For example, If you are cutting .125 acrylic.. set toolpath strategy to cut it with 2 passes with the first being down to a very thin skin (so that you almost have just the protective paper left down there). Then another final pass to do the cut out / seperation of the parts.

Some parts, some materials.. this will help.

 

[astro8]

A (so that you almost have just the protective paper left down there).

Yep, JohnL that was what I was trying to explain except don't cut through the paper, leave it to hold the letters/parts. If your bed is flat it's quite easy to cut out full 8' x4' sheets of small stuff this way.

I agree with iSign, buy that vacuum. A router isn't complete without one, it's like a printer without a take-up reel.

 

[John L]

Yep, JohnL that was what I was trying to explain except don't cut through the paper, leave it to hold the letters/parts. If your bed is flat it's quite easy to cut out full 8' x4' sheets of small stuff this way.

I agree with iSign, buy that vacuum. A router isn't complete without one, it's like a printer without a take-up reel.

Right on. There ways to do an acceptable vac hold down for less than 10 thousand also.

 

[Just Another Sign Guy]

double sided tape as mentioned... i know many production shops that have vacuums and do not use them as well as many shops that do not have vacuums that only use double sided tape...myself if you can afford both definitely get the vacuum but you can work without one.

as far as tape goes my preference is double sided masking tape, leaves no residue..good stuff.

 

[SignManiac]

I use my vacuum on everything except large heavy pieces that are just hog outs or v-carved.

I would hate my CNC if I had to clamp, tape or screw everything down. Well I wouldn't hate it but my employees would hate it. A vac is a smart investment, you are using half of an expensive tool.

 

[gfxsigns]

Thanks for the input everyone.

when you use the double sided tape-do you just do strips down the sheet then? or do you use something like nitto tape and sheet the entire thing out?

 

[J Hill Designs]

I use double sided tape and clamping...no vac here...I just strip down the back - smaller letter sets get strips closer together, larger farther - If I am cutting mirrored (like to put stud hole locations in the back) I use two layers of transfer tape and then double stick to the spoil board

 

[SqueeGee]

We have a vacuum but when doing small parts, we cover the substrate with application tape, then Gudy 909, then run it through the laminator on top of a sheet of cardboard.

This method assumes: a) you bought a huge roll of Gudy 909(we have a 48" roll that must be about 12,000 feet long) a long time ago for another job and realize that it will never get used unless you use it to rout small pieces on your CNC and b) you get your substrates delivered from a company like Harbor who routinely wraps your orders in nice big sheets of cardboard.

What's nice about this method: 1 - the application tape insures a clean, fast, and easy way to remove the Gudy 909 and 2 - you don't have to worry about where the parts line up on the substrate like you do with strips of double sided because the whole sheet is covered.

 

[synergy_jim]

+1 on the app tape.... we do small letters from sheets covered in app tape w/ tape side down and vacuum on. Cut just deep enough to cut the substrate w/o cutting the tape.