Working on plexi (perspex) with cnc

[npbosch]

Hi guysJust noticed some problems I want to share. I just cut some panels with my cnc machine in white 3 mm thick plexiglas (perspex), which went very fine. Then I sprayed primer on it (which was made black to block the light), then the boeing brown colour was sprayed to it.Now I started experimenting with engraving the lines and characters on itWith a 0.8 mm fraise (cutter) I made characters of 5 mm height, with a 0,5 mm fraise I made the 4 mm characters.Sometimes (specially with the smaller characters) the paints gets of the plexi. Especially characters like the "A" (the triangle in the middle) or the character "E" (between the horizontal lines) are troublesome.The fraise is complete new and sharp. Has anybody experiece with this? I use paint made on water basis(just like the primer. If I can not solve this problem, my whole project comes in danger I am afraid.Perhaps I could rub white characters on it (but that will spoil the backlight), anybody know a website were you can buy 4 mm rubbing letters? Those would wear of too during use, I am afraid.RegardsNorberthttp://home.wanadoo.nl/norbert.bosch

[Guest Erups]

Maybe try sanding the panel first and then using acrylic or enamel?

[Garys]

Yep, rub it back with light grade paper. this will give the paint something to stick too. Also be sure to use a plastic primer as standard primers wont adhere to the plastic.This combo should work well.Gary

[Guest Robid]

>Yep, rub it back with light grade paper. this will give the>paint something to stick too. Also be sure to use a plastic>primer as standard primers wont adhere to the plastic.This>combo should work well.>>GaryThanks for the info guys, I'm just about to engrave my front panels and I was thinking in the back of my head.... What sort of paint?Norbert,What type of cutting tool are you using for engraving... are you using a v-shape and if so, are you using skeleton mode in Rams?Also, are you using single line fonts?ThanksDavid

[npbosch]

Hi DavidI did my experimenting with a flat end router (don't know if that is the right name for it though) . It is a cylindical cutter (0,8 mm in diameter). If you look at it from the side , you would see a rectangle. I use the same cutters (with a bit wider diameter) to cut the plexi.I did experiment with V shaped cutters, but was not satisfied with the result. I use AUTOCAD for designing, but that program can not vectorize text, so I import the text from BOBCAD. In Ramsgold I use plain-internal, not skeleton. Skeleton is for the V shaped router AFAIK. With the characters I have, skeleton mode would just mill out the contour of the characters, but I want to remove the complete surface from the character. The result (also with backlighting) look very good. I was very sad when I saw little parts paint comming of at the character A and E as I described above.I think I did not use the right primer (it was for wood, although I asked for plastic in the shop). So know I am going to remove the paint of my panels, sand it thorougly and use new primer. I will post the pics here (hopefully in one week).regardsNorbert

[Guest Robid]

NorbertI look forward to seeing the result.I am using the same type of cutter as you(I think)to cut out the panels, but haven't quite been sure which tool to use for the actual engraving. The tool I'm using is for a dremel and the tool no. is 113 (if that helps).I'm still cncing the back mounting panel for my MCP, so once I'm done that, I'll be starting on the front panel.Just for interest, I've used 4.5mm clear perspex for the back mounting plate, and I'm using 3mm white translucent perspex for the front. This should help with the lettering being visible during the day and backlit during the night.David

[Guest Robid]

Actually Norbert, do you have a graphic or link to an image of the cutter your using?David

[npbosch]

Yes , I have DavidIt is on my website, look under PANELS.http://home.wanadoo.nl/norbert.bosch

[Guest skotten]

Hi NorbertWhere did you buy the CNC router, and much did you pay for it?RegardsPeter

[Guest Robid]

Norbert,I can't see an image of your cutting tool/bit. Can only see cnc.David

[npbosch]

DavidYes , on the pic you see only the machine it self .The bits I use you can see here:http://www.mdaelektronica.nl/nl/dept_34.htmlPeterThe machine is made by:http://www.2004all.com/This is a dutch former furniture maker. He has many many years experience in cnc and I learned a lot from him. He lives not far away from (in Amsterdam , the netherlands)Norbert

[Guest Robid]

Norbert,I am using a very similar bit for cutting, but I was going to use a ball shaped engraving bit at 0.5mm width for the engraving.If anyone is interested, I made my own cnc by collecting lots of ideas from the internet, also free plans and schematics for the driver board (made them myself) shareware software etc. I guess all up, it's cost me about $100 AUD to make.As you can see elsewhere, you can even make your own knobs.David

[Guest Binkles]

I'm sure a lot of people would be interested, I know I will be once I get back into building once I get to Aussie.Thought about making a page about it?

[Guest Robid]

Yes, thought about it, but I don't have webspace to do it.It also takes time away from building.But I'm happy to share any knowledge I have, just as everyone else here is.David

[Guest twabi2]

I can give some webspace if you wantunfortunally, I can't give you extra time :)