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CNC Contour Cut

xxtoni

New Member
We already have a small CNC router but we are looking to buy a 3x2m machine to get maximum efficiency when cutting sheets (foamex and acrylic around here are 3.05x2.05m).

One thing that we do a lot and would like to do on the CNC is contour cutting of printed and applied images on a substrate. So basically I'd like to apply the prints on foamex for example and then have the CNC contour cut the shape of the print. I'd apply a decent bleed on the image so the accuracy doesn't have to be spot on but it should be within a few millimeters.

I've figured already how this could be done for a single instance. You basically put down a small cross when you're printing the image, then you outline the image and export it with the cross to a dxf, import it into your CAM software and use the x as the machining origin for the CNC. Then you apply the print onto the substrate, put it onto the CNC and guide your tool exactly onto the X and set the work piece origin there and just start the process.

The problem I have with this approach though is that if you want to do multiple copies you either have to set the whole thing up in the "drawing" software, compared to making copies in your rip as you normally would.

So far I only see two options on how to do this for dozens of copies automatically:

Do the approach I outlined above with the cross and you just create all the copies in your illustration software and export it all as one dxf file with outlines and just create the paths in your CAM later on with each cross service as the machining origin for each part or you would have to set the x manually for each workpiece, which is really tedious and not something I'd want to do.

Is there any other way to do contour cuts on printed graphics without an optical sensor on the CNC ?

Your help is deeply appreciated!
 

fixtureman

New Member
I do this for a company they put 3 cross hash marks on the sheet and I use a laser pointer to line them up. When I get them lined up I cut it out. It only takes a few seconds for me to do this.
 

xxtoni

New Member
So you do them one by one ?

The reason I'd like an automated solution is so that I can set it all up and continue doing some other work instead of doing this the whole day. That's a whole day wasted not doing something else.
 

SebastienL

New Member
Yes, I think your best option is to repeat the images and cut paths and set up your registration marks in a "drawing" software. I do this all the time.

Unless you can export your cut paths from your rip as a dxf or dwg. Most cnc software will accept an .eps vector file.
 

xxtoni

New Member
I've tried it today and the results were pretty much as I imagined. I'm thinking I'll need a 10mm bleed when doing this and it needs to be perfectly aligned with the edges of the work table but that's all manageable.

One thing I didn't expect though and that could be a problem is the vinyl looking ripped where the bit went through around the edges (to see exactly what I mean take a look at the images below). Is there any way to avoid this with different speeds and RPMs or is it just unavoidable ?

Obviously it can't go to the customer looking like this but when I tried correcting it with an olfa it was pretty difficult. Does this happen to you ?

http://imgur.com/a/AK9l5
 

Davidford7

New Member
I've tried it today and the results were pretty much as I imagined. I'm thinking I'll need a 10mm bleed when doing this and it needs to be perfectly aligned with the edges of the work table but that's all manageable.

One thing I didn't expect though and that could be a problem is the vinyl looking ripped where the bit went through around the edges (to see exactly what I mean take a look at the images below). Is there any way to avoid this with different speeds and RPMs or is it just unavoidable ?

Obviously it can't go to the customer looking like this but when I tried correcting it with an olfa it was pretty difficult. Does this happen to you ?

http://imgur.com/a/AK9l5

Try using s down cut bit. It comes with it's own st of problems but may help.
 

rjssigns

Active Member
The only time I've needed a CNC cut-out I had it cut out first then applied the graphic. Perfect. I know it's not production friendly, but it works.

Need to get my own CNC. Don't think my friend likes tying up his 5-axis Centroid to do my projects.
 

xxtoni

New Member
The only time I've needed a CNC cut-out I had it cut out first then applied the graphic. Perfect. I know it's not production friendly, but it works.

Need to get my own CNC. Don't think my friend likes tying up his 5-axis Centroid to do my projects.

Thanks for the recommend but the whole idea here is saving time and being able to do complicated shapes so post-application contour cut is pretty much a must.

oh and yea...having a full sized CNC is a huge advantage. First because it saves money but second and in my opinion more importantly you are a lot more flexible and you don't have to wait for anyone. Right now we have to drive the foamex to the CNC center, wait for a day or two for them to finish it and then go pick it up again. That's a few hours wasted 2 days of one of our guys who has to drive the foamex up and pick it up and the added project time to the customer. We could cut it from 2-3 days to a few hours in our own shop.
 

Ditchmiester

New Member
We have a NewCNC brand router that has their own proprietary Laser Registration system on it. We just have to print two registration marks and tell the router where they are and it reads them and cuts out the printed shaped. It took them a while to get their software working properly as we were kind of the guinea pig for them with it but now that it works it seems to be pretty accurate to within .010" of an inch.
 

xxtoni

New Member
We have a NewCNC brand router that has their own proprietary Laser Registration system on it. We just have to print two registration marks and tell the router where they are and it reads them and cuts out the printed shaped. It took them a while to get their software working properly as we were kind of the guinea pig for them with it but now that it works it seems to be pretty accurate to within .010" of an inch.

I know, I know...lasers and optical sensors, great and all the rage and I'd love to just buy a Zund, but we're on the shoestring budget and as far as accuracy goes the method I tried is very accurate as well. As long as you line it up properly you can probably get away with a 5-10mm bleed.

How do you solve the issue I posted above though ?

Do you use a downcut bit or something else you do ?
 

Ditchmiester

New Member
We use all Straight Single O Flute bits for cutting plastics and other soft material. For any non-ferrous metals we use Single or two flute upcut bits. What kind of rpm and feeds are you running? You would think our machine was very expensive but it wasn't nearly as bad as you would think. PM me if you want more details about our machine.
 

SebastienL

New Member
For sure, a downcut endmill will help with the print fraying. It's got to be a brand spanking new bit thought...
 

xxtoni

New Member
For sure, a downcut endmill will help with the print fraying. It's got to be a brand spanking new bit thought...

Great, any experience with the single O flute that Ditchmiester mentioned ?

I have a local guy who makes these for me, solid carbide, great quality...makes them in 2 days, much faster than ordering them online and surprisingly enough, cheaper. He can also sharpen them if they're at least 4mm, anything smaller than that is a single use for me.

I guess I'll give him a call and have him make me a downcut and a single o flute.
 

SebastienL

New Member
Yes, Belin or Onsrud... not much difference between 'em!

Personally, I'd be weary of your custom bits. A lot of engineering goes into making endmills: Angle of the cutting edge, angle of the front and back edge of the cutting edge, relief behind the cutting edge, etc... It's not the same for a bit designed to cut aluminum and one to cut pvc/acrylics, even if to the eye they look the same. Unless your guy knows all of these parameters, you will probably get inconsistent results.

I think doing a comparison test with your custom endmill and a store bought endmill is not a bad idea!
 

rjssigns

Active Member
Yes, Belin or Onsrud... not much difference between 'em!

Personally, I'd be weary of your custom bits. A lot of engineering goes into making endmills: Angle of the cutting edge, angle of the front and back edge of the cutting edge, relief behind the cutting edge, etc... It's not the same for a bit designed to cut aluminum and one to cut pvc/acrylics, even if to the eye they look the same. Unless your guy knows all of these parameters, you will probably get inconsistent results.

I think doing a comparison test with your custom endmill and a store bought endmill is not a bad idea!

I'd bet xxtoni's guy is an old tool and die maker that's forgot more than most of these engineers will ever know. Very good friend of mine is 72 years old and supposedly retired from the tool and die trade. He's got people from Austria and Italy coming to his shop to get prototype pieces done.
He just laughs. Asks them why with all their unlimited budgets and degreed engineers they have to come to a an old man in a tiny town in Wisconsin to get their parts made.

He does parts for KTM and Ducati. Now ain't that something?!
 

xxtoni

New Member
I'd bet xxtoni's guy is an old tool and die maker that's forgot more than most of these engineers will ever know. Very good friend of mine is 72 years old and supposedly retired from the tool and die trade. He's got people from Austria and Italy coming to his shop to get prototype pieces done.
He just laughs. Asks them why with all their unlimited budgets and degreed engineers they have to come to a an old man in a tiny town in Wisconsin to get their parts made.

He does parts for KTM and Ducati. Now ain't that something?!

It's quite something and a hell of a coincidence too. I love Ducatis and ride a KTM. My KTM in the production area of our shop - http://i.imgur.com/vNIyyRK.jpg

and yea, I do trust this guy. We don't have a lot of experience with bits but the ones he made for us work a lot better than what we've bought online.

I guess I'll order a single o flute and see how it goes.
 

rjssigns

Active Member
It's quite something and a hell of a coincidence too. I love Ducatis and ride a KTM. My KTM in the production area of our shop - http://i.imgur.com/vNIyyRK.jpg

and yea, I do trust this guy. We don't have a lot of experience with bits but the ones he made for us work a lot better than what we've bought online.

I guess I'll order a single o flute and see how it goes.


Nice bike.

If you watch AMA Superbike(KTM team) or Moto GP(Ducati's) My friend makes parts for those bikes. When Ducati engineers were at his shop they asked what was in all the Snap-On cabinets. He said: Tooling, why? They said at the Ducati race facility they only have a small cabinet with tools for the CNC. Eddy laughed and said: If I can't buy it I make it. He's got over 30 linear feet of cabinets by one cnc. Oh yeah, he builds his own cnc equipment too.
Here is a clip of him in his shop. (hope the link works) http://www.youtube.com/watch?v=agmKuX8CaPs

Ducati pic for link.jpg One of my Duc's
 

xxtoni

New Member
Nice bike.

If you watch AMA Superbike(KTM team) or Moto GP(Ducati's) My friend makes parts for those bikes. When Ducati engineers were at his shop they asked what was in all the Snap-On cabinets. He said: Tooling, why? They said at the Ducati race facility they only have a small cabinet with tools for the CNC. Eddy laughed and said: If I can't buy it I make it. He's got over 30 linear feet of cabinets by one cnc. Oh yeah, he builds his own cnc equipment too.
Here is a clip of him in his shop. (hope the link works) http://www.youtube.com/watch?v=agmKuX8CaPs

View attachment 92494 One of my Duc's

Nice

I'm looking to get a Multistrada 1200 once I have a bit of pocket change.
 

rjssigns

Active Member
I'm looking to get a Multistrada 1200 once I have a bit of pocket change.

Post pics when you get one. That is one model I haven't tried yet. Owners rave about how fast, agile and comfy they are. Supposed to be a good for long hauls too.
I need to win the lottery so I can buy all the bikes I want. It is a sickness I'm told.
 

artbot

New Member
i had to do this in a production situation with my old shopbot for a year or so. ...would have to contour cut about 80 or so of each image. i did the three cross hair marks for a while successfully. in the end, came up with a very cheap laser system.

each print had a 1'x 1' 2 pixel right angle printed at the bottom corner. the cnc table had two lasers painting the table at a right angle. i would just slide the print "under" the lasered right angle so that the black 1' x 1' lined up with the lasered lines and hit the vacuum without a single fear of being off. it was very quick. the tool doesn't have to go anywhere to ID the cut point.

these levels can be also mounted remotely on a pedestal near the cnc to not obstruct.
 

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