[ssutton]

Thanks for all the responses a couple of weeks ago asking for help with vinyl cutting. I ordered the parts and installed them this past week. Special thanks to mkc2 for the final pieces to the puzzle.

Here are the results in pics. Using TurboCad17 deluxe to generate the DXF files and then SheetCam for the CAM. The trick to using a drag knife with SheetCam is to use the arc lead in and arc lead (Thanks Les) out settings. This assures that the start cut and final cut overlap to compensate for the blade changing angles. For very little money this adds a nice feature to our CNC machines, I can now label and brand things that I make with my machine without having to purchase another machine.

Scott




link to original thread;
http://www.cnczone.com/forums/diy-cn...ting_head.html

[mkc2]

Good to hear it's all up and running.
Cheers Michael

[freecncplans]

How did you hold the material down?

Sean

[Walky]

I guess it's important to do a small overcut at the lead in/out, right?
The results look great! Exactly what holder/blade did you buy finally? I've been looking at those for some time on Ebay but I have some doubts about them. I understand the knife rotates freely, but is it spring loaded in the holder itself?, how do you install the knife in the holder?

If it's spring loaded, it would be tempting to try and use the holder with a diamond bit to engrave glass.


Edit: Just checked the original topic, it's a little clearer now, but it would still be nice to have some hands-on info about your holder and knives, hopefully lots of pictures!

Thanks!

[ssutton]

The lead in and lead out is important because the blade changes its angle depending on the direction of cut, so it is very probable that there will be a tiny bit of vinyl that is not cut completely thru on every cut at the beginning and end of the cut (letter, etc.) Real vinyl cutters have this software function made into them. The blade pressure is pure gravity, having said that. It is really important to use a small linear slide because if you use a large one the weight of it alone will cause the cutter to cut clean thru the paper backing of the vinyl. I used the one that mkc2 linked me to in the original post. As far as the roland blade holder I bought this one on ebay;
Roland Cutter Blade Holder with 3 blades SHIPS FROM USA | eBay
This guy is a great seller on ebay, he answered lots of questions for me about how to use it.

The vinyl is held down by vacuum, my table top is MDF and I draw vacuum thru it to hold down material. I suppose that other methods may work equally well like taping down the vinyl? To cut the vinyl, I use an extra piece of 1/4 MDF that I lay on top of my sacrificial MDF that is cut up and not smooth. The 1/4 is new and flat, the vacuum draws thru the 1/4 and I lay the vinyl on top of that so that I am cutting on a smooth surface.

I can post pics later today when I am back in the shop if anyone would like.

Scott

[mkc2]

All I do is tape it with masking tape around the edges keeping it tight on some MDF, then adjust the bottom of the holder down so the blade just has enough depth to cut the vinyl and this also keeps the vinyl flat as it cuts.

[Walky]

Thanks for the info

What I meant about using overcut is to compensate for the small knife tip offset (I guess there's an offset), is that right?

[ssutton]

Not totally sure that I am following your question Walky, sorry. The knife tip is so small that an offset to the outside is not really necessary. The challenge when cutting with a CNC is that a normal vinyl cutter using a drag knife will overshoot the start/end points so that no matter the orientation of the cutter blade when it entered the material it will be sure to fully cut thru the vinyl and close the cut so that it is completely free from the rest of the vinyl. I have tricked my CNC into this by using the arc start in and arc finish in the CAM software to simulate this function. I created a tool in CAM (sheetcam) that was .001 diameter. Then I DO use an outside offset only to assure that the arc start/finish will always be to the outside of the shape that I am cutting. The pic shows the setup in sheetcam.

Hope that helps, its really not complicated at all. Once you build it, you will figure out the rest in short order.

Scott

[Walky]

Thanks again for your answer. What I mean is that I guess the knife tip must be slightly off center to allow it to self correct its orientation when cutting (I might be wrong).

What I mean by overcut is the following (on the right), I always use a small overcut when router cutting since it usually gives a better finish at the lead in and lead out points:

[Walky]

Oh, by the way, do you think it would be able to cut thin rubber?

[riche543]

Most of you may have already seen this post. I used this idea works really well . http://www.cnczone.com/forums/diy-cn...r_diy_mdf.html


Sent from my iPhone using Tapatalk

[ssutton]

The blade tip does appear to be slightly off center (It is very small and hard to see). It should cut thru rubber that is very thin.