Mister for Acrylic

[dcruze]

I have been routing and engraving 3/8" LED lit acrylic. I have adjusted speeds and feeds and have used compressed air to help keep it cool and clear away chips, but is seems that I still have problems with chips sticking in the grooves.

I started experimenting and thinking about a mister on acrylic. I sprayed WD40 onto my acrylic before routing and came away with almost a perfect route without any chips in the grooves.

Has anyone used a mister on acrylic?
If so what do you use for fluid? I tried plain water but it doesn't work as well as the WD40?

I'm looking for ideas before I buy a mister to try.

[scottp55]

TJ, In one of his classes (Cutting plastics maybe) used a combination mister/blower I wrote down in my notes as a "ColdGun" that they use when cutting the Desktop enclosures?.
Maybe somebody else can chime in and help more.
The way he mentioned it was as an "accessory" , so maybe Shopbot sells them?

[dcruze]

Yea I looked at the Cold Air Guns, but they are expensive to by and use a high volume of air and the air has to be free of moisture or they freeze.

Does anyone know if the oils used in the misters will hurt or damage the acrylic?

Is there something else to use besides oils?

[Burkhardt]

I have seen liquid soap mentioned as lubricant and surfactant additive to water (not sure how much). It wont damage acrylic but the dried mist may make be a sticky soap film on the surrounding surfaces.

I don't normally use lubricants to keep my machine dry. But at one time for a larger aluminum job I rigged up a temporary water mister with one of the personal cooling misters from the sports store. Probably not a good solution if you do that frequently.

[dcruze]

I ran some test trying dish soap, alcohol, vegtable oil, and WD40. WD40 works the best, but after investigating it says it can cause crazing in the plastic.

[ntraub01]

I do quite a bit of plex work and I'm wondering...are the chips "sticking" in the grooves like they are actually solidifying and sticking, or are they just getting stuck/caught in the grooves?? If they are actually solidifying and sticking then my guess is that they are getting way to hot and either the feed rate needs to be increased or the RPMs need to come down or both.

It is true that WD40 will certainly cause crazing and so will alcohol. The only alcohol they recommend using is isopropyl (rubbing) and even then only after all of the machining is complete. Vegetable oil may work but getting it off the plex will be a pain...how about something like Pam though getting it off will again be a pain. Dish soap in a 10:1 mixture with deionized water would probably work the best. They actually recommend cleaning all plex with a dish soap & water mixture over any other cleaner.

YET, if you cool the chips down so they aren't molten on even close to molten you will solve the entire problem without using any sort of coolant/lubricant.

Good luck,

[Bob Eustace]

Dale we use 3/8 perspex all the time for trophies and have never needed misting or air. Are you using "cast acyrilic" as other varieties dont machine as cleanly. It is essential to use very sharp cutters and its a good move to use cutters dedicated to plastic use only. When dull they usually still work OK on hardwood so theres really is no waste. I would try different speeds and feeds on a test piece and engrave these details on the piece so you have a reference. My gut feel is your cutting is not agressive enough and is rubbing causing heat. Our best results occur when you get shavings in little balls. Quick Engrave also gives the best results if you are doing text. We use bog standard 90 degree vee bits for this as they work great on text and graphics.

[POPS 64]

Dale , fast feed rate , low rpm . make sure it's cast , if your not doing 3-D and just etching you should try a drag bit . What depth are you trying when I V-carve I go .05 . Jeff

[dcruze]

Thanks everyone. I have tried lots of different feeds and speed. The chips seem to stick in the grooves and you can pick them out with a pointed instrument. I am cutting 3/8" extruded acrylic @10,000 rpm on the router and a feed of 1 ips. I have been blowing compressed air across it as it cut with OK results. Sometimes I get good cuts I am just looking for a way to get a better cut with less cleanup.

If someone gives me some other feed I will test them out.

Attached is a photo of some of the led's I have made.

[Xray]

For sure would have much better results with 0 melting issues using a drag bit, well worth the investment if you do alot of 2d plexi work. They also work well on marble, metals, glass quite a variety ... You just aren't going to get depth with them, and for edge lit, depth is not what you need but detail, such as the one I did below.

http://www.ebay.com/itm/1-4-DIA-DIAMOND-DRAG-ENGRAVING-BIT-STAINLESS-BODY-TAIG-SHERLINE-CNC-MINI-MILL-/281465667010?pt=LH_DefaultDomain_0&hash=item4188a93dc2

[gundog]

I have a Unist MQL system on my machine but I have not used it much yet. Do a google search it sounds like what you are looking for. What size bit are you using and how many flutes? If you have a model number of the bit post it. Do you know what the chip load on the bit should be? feeds and speeds are not hard to calculate if you have the chip load.

Mike

[feinddj]

Cast will machine well when extruded, with the same bits, same feeds and rpms will melt, wrap and do all sorts of awful stuff. I just make my clients spend the extra to buy cast. If they won't I don't cut it.

David

[dcruze]

Thanks, a lot of my cuts are with 1/4" 60 degree v-bit. I will experiment with increasing my speed and see what happens. I will also check into the price of cast acrylic.

I'll let you know what happens.

[POPS 64]

Dale , check this site out they have great prices , shipping , and any size or thickness you want. estreetplastics.com good luck Jeff

[dcruze]

Thanks, I will check it out.